* [PATCH v4 0/7] Partial Parity Log for MD RAID 5
@ 2017-02-21 19:43 Artur Paszkiewicz
2017-02-21 19:43 ` [PATCH v4 1/7] md: superblock changes for PPL Artur Paszkiewicz
` (7 more replies)
0 siblings, 8 replies; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-02-21 19:43 UTC (permalink / raw)
To: shli; +Cc: linux-raid, Artur Paszkiewicz
This series of patches implements the Partial Parity Log for RAID5 arrays. The
purpose of this feature is closing the RAID 5 Write Hole. It is a solution
alternative to the existing raid5-cache, but the logging workflow and much of
the implementation is based on it.
The main differences compared to raid5-cache is that PPL is a distributed log -
it is stored on array member drives in the metadata area and does not require a
dedicated journaling drive. Write performance is reduced by up to 30%-40% but
it scales with the number of drives in the array and the journaling drive does
not become a bottleneck or a single point of failure. PPL does not protect from
losing in-flight data, only from silent data corruption. More details about how
the log works can be found in patches 3 and 5.
This feature originated from Intel RSTe, which uses IMSM metadata. This
patchset implements PPL for external metadata (specifically IMSM) as well as
native MD v1.x metadata.
Changes in mdadm are also required to make this fully usable. Patches for mdadm
will be sent later.
v4:
- Separated raid5-cache and ppl structures.
- Removed the policy logic from raid5-cache, ppl calls moved to raid5 core.
- Checking wrong configuration when validating superblock.
- Moved documentation to separate file.
- More checks for ppl sector/size.
- Some small fixes and improvements.
v3:
- Fixed alignment issues in the metadata structures.
- Removed reading IMSM signature from superblock.
- Removed 'rwh_policy' and per-device JournalPpl flags, added
'consistency_policy', 'ppl_sector' and 'ppl_size' sysfs attributes.
- Reworked and simplified disk removal logic.
- Debug messages in raid5-ppl.c converted to pr_debug().
- Fixed some bugs in logging and recovery code.
- Improved descriptions and documentation.
v2:
- Fixed wrong PPL size calculation for IMSM.
- Simplified full stripe write case.
- Removed direct access to bi_io_vec.
- Handle failed bio_add_page().
Artur Paszkiewicz (7):
md: superblock changes for PPL
raid5: calculate partial parity for a stripe
raid5-ppl: Partial Parity Log write logging implementation
md: add sysfs entries for PPL
raid5-ppl: load and recover the log
raid5-ppl: support disk hot add/remove with PPL
raid5-ppl: runtime PPL enabling or disabling
Documentation/admin-guide/md.rst | 32 +-
Documentation/md/raid5-ppl.txt | 44 ++
drivers/md/Makefile | 2 +-
drivers/md/md.c | 140 +++++
drivers/md/md.h | 10 +
drivers/md/raid0.c | 3 +-
drivers/md/raid1.c | 3 +-
drivers/md/raid5-ppl.c | 1151 ++++++++++++++++++++++++++++++++++++++
drivers/md/raid5.c | 227 +++++++-
drivers/md/raid5.h | 19 +
include/uapi/linux/raid/md_p.h | 44 +-
11 files changed, 1657 insertions(+), 18 deletions(-)
create mode 100644 Documentation/md/raid5-ppl.txt
create mode 100644 drivers/md/raid5-ppl.c
--
2.11.0
^ permalink raw reply [flat|nested] 25+ messages in thread
* [PATCH v4 1/7] md: superblock changes for PPL
2017-02-21 19:43 [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
@ 2017-02-21 19:43 ` Artur Paszkiewicz
2017-02-21 19:43 ` [PATCH v4 2/7] raid5: calculate partial parity for a stripe Artur Paszkiewicz
` (6 subsequent siblings)
7 siblings, 0 replies; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-02-21 19:43 UTC (permalink / raw)
To: shli; +Cc: linux-raid, Artur Paszkiewicz
Include information about PPL location and size into mdp_superblock_1
and copy it to/from rdev. Because PPL is mutually exclusive with bitmap,
put it in place of 'bitmap_offset'. Add a new flag MD_FEATURE_PPL for
'feature_map', analogically to MD_FEATURE_BITMAP_OFFSET. Add MD_HAS_PPL
to mddev->flags to indicate that PPL is enabled on an array.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
---
drivers/md/md.c | 19 +++++++++++++++++++
drivers/md/md.h | 8 ++++++++
drivers/md/raid0.c | 3 ++-
drivers/md/raid1.c | 3 ++-
include/uapi/linux/raid/md_p.h | 18 ++++++++++++++----
5 files changed, 45 insertions(+), 6 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 55e7e7a8714e..c2028007b209 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1514,6 +1514,12 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
} else if (sb->bblog_offset != 0)
rdev->badblocks.shift = 0;
+ if (le32_to_cpu(sb->feature_map) & MD_FEATURE_PPL) {
+ rdev->ppl.offset = (__s16)le16_to_cpu(sb->ppl.offset);
+ rdev->ppl.size = le16_to_cpu(sb->ppl.size);
+ rdev->ppl.sector = rdev->sb_start + rdev->ppl.offset;
+ }
+
if (!refdev) {
ret = 1;
} else {
@@ -1626,6 +1632,13 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
if (le32_to_cpu(sb->feature_map) & MD_FEATURE_JOURNAL)
set_bit(MD_HAS_JOURNAL, &mddev->flags);
+
+ if (le32_to_cpu(sb->feature_map) & MD_FEATURE_PPL) {
+ if (le32_to_cpu(sb->feature_map) &
+ (MD_FEATURE_BITMAP_OFFSET | MD_FEATURE_JOURNAL))
+ return -EINVAL;
+ set_bit(MD_HAS_PPL, &mddev->flags);
+ }
} else if (mddev->pers == NULL) {
/* Insist of good event counter while assembling, except for
* spares (which don't need an event count) */
@@ -1839,6 +1852,12 @@ static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
if (test_bit(MD_HAS_JOURNAL, &mddev->flags))
sb->feature_map |= cpu_to_le32(MD_FEATURE_JOURNAL);
+ if (test_bit(MD_HAS_PPL, &mddev->flags)) {
+ sb->feature_map |= cpu_to_le32(MD_FEATURE_PPL);
+ sb->ppl.offset = cpu_to_le16(rdev->ppl.offset);
+ sb->ppl.size = cpu_to_le16(rdev->ppl.size);
+ }
+
rdev_for_each(rdev2, mddev) {
i = rdev2->desc_nr;
if (test_bit(Faulty, &rdev2->flags))
diff --git a/drivers/md/md.h b/drivers/md/md.h
index b8859cbf84b6..66a5a16e79f7 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -122,6 +122,13 @@ struct md_rdev {
* sysfs entry */
struct badblocks badblocks;
+
+ struct {
+ short offset; /* Offset from superblock to start of PPL.
+ * Not used by external metadata. */
+ unsigned int size; /* Size in sectors of the PPL space */
+ sector_t sector; /* First sector of the PPL space */
+ } ppl;
};
enum flag_bits {
Faulty, /* device is known to have a fault */
@@ -229,6 +236,7 @@ enum mddev_flags {
* supported as calls to md_error() will
* never cause the array to become failed.
*/
+ MD_HAS_PPL, /* The raid array has PPL feature set */
};
enum mddev_sb_flags {
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index b3d264452fd5..1b6aa9a53149 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -29,7 +29,8 @@
#define UNSUPPORTED_MDDEV_FLAGS \
((1L << MD_HAS_JOURNAL) | \
(1L << MD_JOURNAL_CLEAN) | \
- (1L << MD_FAILFAST_SUPPORTED))
+ (1L << MD_FAILFAST_SUPPORTED) |\
+ (1L << MD_HAS_PPL))
static int raid0_congested(struct mddev *mddev, int bits)
{
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 2e5e4805cbe1..a95e08501619 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -44,7 +44,8 @@
#define UNSUPPORTED_MDDEV_FLAGS \
((1L << MD_HAS_JOURNAL) | \
- (1L << MD_JOURNAL_CLEAN))
+ (1L << MD_JOURNAL_CLEAN) | \
+ (1L << MD_HAS_PPL))
/*
* Number of guaranteed r1bios in case of extreme VM load:
diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
index 9930f3e9040f..fe2112810c43 100644
--- a/include/uapi/linux/raid/md_p.h
+++ b/include/uapi/linux/raid/md_p.h
@@ -242,10 +242,18 @@ struct mdp_superblock_1 {
__le32 chunksize; /* in 512byte sectors */
__le32 raid_disks;
- __le32 bitmap_offset; /* sectors after start of superblock that bitmap starts
- * NOTE: signed, so bitmap can be before superblock
- * only meaningful of feature_map[0] is set.
- */
+ union {
+ __le32 bitmap_offset; /* sectors after start of superblock that bitmap starts
+ * NOTE: signed, so bitmap can be before superblock
+ * only meaningful of feature_map[0] is set.
+ */
+
+ /* only meaningful when feature_map[MD_FEATURE_PPL] is set */
+ struct {
+ __le16 offset; /* sectors from start of superblock that ppl starts (signed) */
+ __le16 size; /* ppl size in sectors */
+ } ppl;
+ };
/* These are only valid with feature bit '4' */
__le32 new_level; /* new level we are reshaping to */
@@ -318,6 +326,7 @@ struct mdp_superblock_1 {
*/
#define MD_FEATURE_CLUSTERED 256 /* clustered MD */
#define MD_FEATURE_JOURNAL 512 /* support write cache */
+#define MD_FEATURE_PPL 1024 /* support PPL */
#define MD_FEATURE_ALL (MD_FEATURE_BITMAP_OFFSET \
|MD_FEATURE_RECOVERY_OFFSET \
|MD_FEATURE_RESHAPE_ACTIVE \
@@ -328,6 +337,7 @@ struct mdp_superblock_1 {
|MD_FEATURE_RECOVERY_BITMAP \
|MD_FEATURE_CLUSTERED \
|MD_FEATURE_JOURNAL \
+ |MD_FEATURE_PPL \
)
struct r5l_payload_header {
--
2.11.0
^ permalink raw reply related [flat|nested] 25+ messages in thread
* [PATCH v4 2/7] raid5: calculate partial parity for a stripe
2017-02-21 19:43 [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
2017-02-21 19:43 ` [PATCH v4 1/7] md: superblock changes for PPL Artur Paszkiewicz
@ 2017-02-21 19:43 ` Artur Paszkiewicz
2017-02-27 23:45 ` Shaohua Li
2017-02-21 19:43 ` [PATCH v4 3/7] raid5-ppl: Partial Parity Log write logging implementation Artur Paszkiewicz
` (5 subsequent siblings)
7 siblings, 1 reply; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-02-21 19:43 UTC (permalink / raw)
To: shli; +Cc: linux-raid, Artur Paszkiewicz
Attach a page for holding the partial parity data to stripe_head.
Allocate it only if mddev has the MD_HAS_PPL flag set.
Partial parity is the xor of not modified data chunks of a stripe and is
calculated as follows:
- reconstruct-write case:
xor data from all not updated disks in a stripe
- read-modify-write case:
xor old data and parity from all updated disks in a stripe
Implement it using the async_tx API and integrate into raid_run_ops().
It must be called when we still have access to old data, so do it when
STRIPE_OP_BIODRAIN is set, but before ops_run_prexor5(). The result is
stored into sh->ppl_page.
Partial parity is not meaningful for full stripe write and is not stored
in the log or used for recovery, so don't attempt to calculate it when
stripe has STRIPE_FULL_WRITE.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
---
drivers/md/raid5.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++
drivers/md/raid5.h | 3 ++
2 files changed, 103 insertions(+)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 7b7722bb2e8d..02e02fe5b04e 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -463,6 +463,11 @@ static void shrink_buffers(struct stripe_head *sh)
sh->dev[i].page = NULL;
put_page(p);
}
+
+ if (sh->ppl_page) {
+ put_page(sh->ppl_page);
+ sh->ppl_page = NULL;
+ }
}
static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
@@ -479,6 +484,13 @@ static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
sh->dev[i].page = page;
sh->dev[i].orig_page = page;
}
+
+ if (test_bit(MD_HAS_PPL, &sh->raid_conf->mddev->flags)) {
+ sh->ppl_page = alloc_page(gfp);
+ if (!sh->ppl_page)
+ return 1;
+ }
+
return 0;
}
@@ -1974,6 +1986,55 @@ static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu
&sh->ops.zero_sum_result, percpu->spare_page, &submit);
}
+static struct dma_async_tx_descriptor *
+ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
+ struct dma_async_tx_descriptor *tx)
+{
+ int disks = sh->disks;
+ struct page **xor_srcs = flex_array_get(percpu->scribble, 0);
+ int count = 0, pd_idx = sh->pd_idx, i;
+ struct async_submit_ctl submit;
+
+ pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
+
+ /*
+ * Partial parity is the XOR of stripe data chunks that are not changed
+ * during the write request. Depending on available data
+ * (read-modify-write vs. reconstruct-write case) we calculate it
+ * differently.
+ */
+ if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
+ /* rmw: xor old data and parity from updated disks */
+ for (i = disks; i--;) {
+ struct r5dev *dev = &sh->dev[i];
+ if (test_bit(R5_Wantdrain, &dev->flags) || i == pd_idx)
+ xor_srcs[count++] = dev->page;
+ }
+ } else if (sh->reconstruct_state == reconstruct_state_drain_run) {
+ /* rcw: xor data from all not updated disks */
+ for (i = disks; i--;) {
+ struct r5dev *dev = &sh->dev[i];
+ if (test_bit(R5_UPTODATE, &dev->flags))
+ xor_srcs[count++] = dev->page;
+ }
+ } else {
+ return tx;
+ }
+
+ init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, tx, NULL, sh,
+ flex_array_get(percpu->scribble, 0)
+ + sizeof(struct page *) * (sh->disks + 2));
+
+ if (count == 1)
+ tx = async_memcpy(sh->ppl_page, xor_srcs[0], 0, 0, PAGE_SIZE,
+ &submit);
+ else
+ tx = async_xor(sh->ppl_page, xor_srcs, 0, count, PAGE_SIZE,
+ &submit);
+
+ return tx;
+}
+
static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
{
int overlap_clear = 0, i, disks = sh->disks;
@@ -2004,6 +2065,9 @@ static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
async_tx_ack(tx);
}
+ if (test_bit(STRIPE_OP_PARTIAL_PARITY, &ops_request))
+ tx = ops_run_partial_parity(sh, percpu, tx);
+
if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
if (level < 6)
tx = ops_run_prexor5(sh, percpu, tx);
@@ -3079,6 +3143,12 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
s->locked++;
}
+ if (level == 5 && sh->ppl_page &&
+ test_bit(STRIPE_OP_BIODRAIN, &s->ops_request) &&
+ !test_bit(STRIPE_FULL_WRITE, &sh->state) &&
+ test_bit(R5_Insync, &sh->dev[pd_idx].flags))
+ set_bit(STRIPE_OP_PARTIAL_PARITY, &s->ops_request);
+
pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
__func__, (unsigned long long)sh->sector,
s->locked, s->ops_request);
@@ -3126,6 +3196,36 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
goto overlap;
+ if (forwrite && sh->ppl_page) {
+ /*
+ * With PPL only writes to consecutive data chunks within a
+ * stripe are allowed because for a single stripe_head we can
+ * only have one PPL entry at a time, which describes one data
+ * range. Not really an overlap, but wait_for_overlap can be
+ * used to handle this.
+ */
+ sector_t sector;
+ sector_t first = 0;
+ sector_t last = 0;
+ int count = 0;
+ int i;
+
+ for (i = 0; i < sh->disks; i++) {
+ if (i != sh->pd_idx &&
+ (i == dd_idx || sh->dev[i].towrite)) {
+ sector = sh->dev[i].sector;
+ if (count == 0 || sector < first)
+ first = sector;
+ if (sector > last)
+ last = sector;
+ count++;
+ }
+ }
+
+ if (first + conf->chunk_sectors * (count - 1) != last)
+ goto overlap;
+ }
+
if (!forwrite || previous)
clear_bit(STRIPE_BATCH_READY, &sh->state);
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 4bb27b97bf6b..3cc4cb28f7e6 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -228,6 +228,8 @@ struct stripe_head {
struct list_head log_list;
sector_t log_start; /* first meta block on the journal */
struct list_head r5c; /* for r5c_cache->stripe_in_journal */
+
+ struct page *ppl_page; /* partial parity of this stripe */
/**
* struct stripe_operations
* @target - STRIPE_OP_COMPUTE_BLK target
@@ -400,6 +402,7 @@ enum {
STRIPE_OP_BIODRAIN,
STRIPE_OP_RECONSTRUCT,
STRIPE_OP_CHECK,
+ STRIPE_OP_PARTIAL_PARITY,
};
/*
--
2.11.0
^ permalink raw reply related [flat|nested] 25+ messages in thread
* [PATCH v4 3/7] raid5-ppl: Partial Parity Log write logging implementation
2017-02-21 19:43 [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
2017-02-21 19:43 ` [PATCH v4 1/7] md: superblock changes for PPL Artur Paszkiewicz
2017-02-21 19:43 ` [PATCH v4 2/7] raid5: calculate partial parity for a stripe Artur Paszkiewicz
@ 2017-02-21 19:43 ` Artur Paszkiewicz
2017-02-28 0:04 ` Shaohua Li
2017-02-21 19:43 ` [PATCH v4 4/7] md: add sysfs entries for PPL Artur Paszkiewicz
` (4 subsequent siblings)
7 siblings, 1 reply; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-02-21 19:43 UTC (permalink / raw)
To: shli; +Cc: linux-raid, Artur Paszkiewicz
This implements the PPL write logging functionality. The description
of PPL is added to the documentation. More details can be found in the
comments in raid5-ppl.c.
Put the PPL metadata structures to md_p.h because userspace tools
(mdadm) will also need to read/write PPL.
Warn about using PPL with enabled disk volatile write-back cache for
now. It can be removed once disk cache flushing before writing PPL is
implemented.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
---
Documentation/md/raid5-ppl.txt | 44 +++
drivers/md/Makefile | 2 +-
drivers/md/raid5-ppl.c | 617 +++++++++++++++++++++++++++++++++++++++++
drivers/md/raid5.c | 49 +++-
drivers/md/raid5.h | 8 +
include/uapi/linux/raid/md_p.h | 26 ++
6 files changed, 738 insertions(+), 8 deletions(-)
create mode 100644 Documentation/md/raid5-ppl.txt
create mode 100644 drivers/md/raid5-ppl.c
diff --git a/Documentation/md/raid5-ppl.txt b/Documentation/md/raid5-ppl.txt
new file mode 100644
index 000000000000..127072b09363
--- /dev/null
+++ b/Documentation/md/raid5-ppl.txt
@@ -0,0 +1,44 @@
+Partial Parity Log
+
+Partial Parity Log (PPL) is a feature available for RAID5 arrays. The issue
+addressed by PPL is that after a dirty shutdown, parity of a particular stripe
+may become inconsistent with data on other member disks. If the array is also
+in degraded state, there is no way to recalculate parity, because one of the
+disks is missing. This can lead to silent data corruption when rebuilding the
+array or using it is as degraded - data calculated from parity for array blocks
+that have not been touched by a write request during the unclean shutdown can
+be incorrect. Such condition is known as the RAID5 Write Hole. Because of
+this, md by default does not allow starting a dirty degraded array.
+
+Partial parity for a write operation is the XOR of stripe data chunks not
+modified by this write. It is just enough data needed for recovering from the
+write hole. XORing partial parity with the modified chunks produces parity for
+the stripe, consistent with its state before the write operation, regardless of
+which chunk writes have completed. If one of the not modified data disks of
+this stripe is missing, this updated parity can be used to recover its
+contents. PPL recovery is also performed when starting an array after an
+unclean shutdown and all disks are available, eliminating the need to resync
+the array. Because of this, using write-intent bitmap and PPL together is not
+supported.
+
+When handling a write request PPL writes partial parity before new data and
+parity are dispatched to disks. PPL is a distributed log - it is stored on
+array member drives in the metadata area, on the parity drive of a particular
+stripe. It does not require a dedicated journaling drive. Write performance is
+reduced by up to 30%-40% but it scales with the number of drives in the array
+and the journaling drive does not become a bottleneck or a single point of
+failure.
+
+Unlike raid5-cache, the other solution in md for closing the write hole, PPL is
+not a true journal. It does not protect from losing in-flight data, only from
+silent data corruption. If a dirty disk of a stripe is lost, no PPL recovery is
+performed for this stripe (parity is not updated). So it is possible to have
+arbitrary data in the written part of a stripe if that disk is lost. In such
+case the behavior is the same as in plain raid5.
+
+PPL is available for md version-1 metadata and external (specifically IMSM)
+metadata arrays. It can be enabled using mdadm option --consistency-policy=ppl.
+
+Currently, volatile write-back cache should be disabled on all member drives
+when using PPL. Otherwise it cannot guarantee consistency in case of power
+failure.
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 3cbda1af87a0..4d48714ccc6b 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -18,7 +18,7 @@ dm-cache-cleaner-y += dm-cache-policy-cleaner.o
dm-era-y += dm-era-target.o
dm-verity-y += dm-verity-target.o
md-mod-y += md.o bitmap.o
-raid456-y += raid5.o raid5-cache.o
+raid456-y += raid5.o raid5-cache.o raid5-ppl.o
# Note: link order is important. All raid personalities
# and must come before md.o, as they each initialise
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
new file mode 100644
index 000000000000..a00cabf1adf6
--- /dev/null
+++ b/drivers/md/raid5-ppl.c
@@ -0,0 +1,617 @@
+/*
+ * Partial Parity Log for closing the RAID5 write hole
+ * Copyright (c) 2017, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include <linux/crc32c.h>
+#include <linux/raid/md_p.h>
+#include "md.h"
+#include "raid5.h"
+
+/*
+ * PPL consists of a 4KB header (struct ppl_header) and at least 128KB for
+ * partial parity data. The header contains an array of entries
+ * (struct ppl_header_entry) which describe the logged write requests.
+ * Partial parity for the entries comes after the header, written in the same
+ * sequence as the entries:
+ *
+ * Header
+ * entry0
+ * ...
+ * entryN
+ * PP data
+ * PP for entry0
+ * ...
+ * PP for entryN
+ *
+ * Every entry holds a checksum of its partial parity, the header also has a
+ * checksum of the header itself. Entries for full stripes writes contain no
+ * partial parity, they only mark the stripes for which parity should be
+ * recalculated after an unclean shutdown.
+ *
+ * A write request is always logged to the PPL instance stored on the parity
+ * disk of the corresponding stripe. For each member disk there is one ppl_log
+ * used to handle logging for this disk, independently from others. They are
+ * grouped in child_logs array in struct ppl_conf, which is assigned to
+ * r5conf->ppl and used in raid5 core.
+ *
+ * ppl_io_unit represents a full PPL write, header_page contains the ppl_header.
+ * PPL entries for logged stripes are added in ppl_log_stripe(). A stripe can
+ * be appended to the last entry if the chunks to write are the same, otherwise
+ * a new entry is added. Checksums of entries are calculated incrementally as
+ * stripes containing partial parity are being added to entries.
+ * ppl_submit_iounit() calculates the checksum of the header and submits a bio
+ * containing the header page and partial parity pages (sh->ppl_page) for all
+ * stripes of the io_unit. When the PPL write completes, the stripes associated
+ * with the io_unit are released and raid5d starts writing their data and
+ * parity. When all stripes are written, the io_unit is freed and the next can
+ * be submitted.
+ *
+ * An io_unit is used to gather stripes until it is submitted or becomes full
+ * (if the maximum number of entries or size of PPL is reached). Another io_unit
+ * can't be submitted until the previous has completed (PPL and stripe
+ * data+parity is written). The log->io_list tracks all io_units of a log
+ * (for a single member disk). New io_units are added to the end of the list
+ * and the first io_unit is submitted, if it is not submitted already.
+ * The current io_unit accepting new stripes is always at the end of the list.
+ */
+
+struct ppl_conf {
+ struct mddev *mddev;
+
+ /* array of child logs, one for each raid disk */
+ struct ppl_log *child_logs;
+ int count;
+
+ int block_size; /* the logical block size used for data_sector
+ * in ppl_header_entry */
+ u32 signature; /* raid array identifier */
+ atomic64_t seq; /* current log write sequence number */
+
+ struct kmem_cache *io_kc;
+ mempool_t *io_pool;
+ struct bio_set *bs;
+ mempool_t *meta_pool;
+};
+
+struct ppl_log {
+ struct ppl_conf *ppl_conf; /* shared between all log instances */
+
+ struct md_rdev *rdev; /* array member disk associated with
+ * this log instance */
+ struct mutex io_mutex;
+ struct ppl_io_unit *current_io; /* current io_unit accepting new data
+ * always at the end of io_list */
+ spinlock_t io_list_lock;
+ struct list_head io_list; /* all io_units of this log */
+ struct list_head no_mem_stripes;/* stripes to retry if failed to
+ * allocate io_unit */
+};
+
+struct ppl_io_unit {
+ struct ppl_log *log;
+
+ struct page *header_page; /* for ppl_header */
+
+ unsigned int entries_count; /* number of entries in ppl_header */
+ unsigned int pp_size; /* total size current of partial parity */
+
+ u64 seq; /* sequence number of this log write */
+ struct list_head log_sibling; /* log->io_list */
+
+ struct list_head stripe_list; /* stripes added to the io_unit */
+ atomic_t pending_stripes; /* how many stripes not written to raid */
+
+ bool submitted; /* true if write to log started */
+};
+
+static struct ppl_io_unit *ppl_new_iounit(struct ppl_log *log,
+ struct stripe_head *sh)
+{
+ struct ppl_conf *ppl_conf = log->ppl_conf;
+ struct ppl_io_unit *io;
+ struct ppl_header *pplhdr;
+
+ io = mempool_alloc(ppl_conf->io_pool, GFP_ATOMIC);
+ if (!io)
+ return NULL;
+
+ memset(io, 0, sizeof(*io));
+ io->log = log;
+ INIT_LIST_HEAD(&io->log_sibling);
+ INIT_LIST_HEAD(&io->stripe_list);
+ atomic_set(&io->pending_stripes, 0);
+
+ io->header_page = mempool_alloc(ppl_conf->meta_pool, GFP_NOIO);
+ pplhdr = page_address(io->header_page);
+ clear_page(pplhdr);
+ memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
+ pplhdr->signature = cpu_to_le32(ppl_conf->signature);
+
+ io->seq = atomic64_add_return(1, &ppl_conf->seq);
+ pplhdr->generation = cpu_to_le64(io->seq);
+
+ return io;
+}
+
+static int ppl_log_stripe(struct ppl_log *log, struct stripe_head *sh)
+{
+ struct ppl_io_unit *io = log->current_io;
+ struct ppl_header_entry *e = NULL;
+ struct ppl_header *pplhdr;
+ int i;
+ sector_t data_sector = 0;
+ int data_disks = 0;
+ unsigned int entry_space = (log->rdev->ppl.size << 9) - PPL_HEADER_SIZE;
+ struct r5conf *conf = sh->raid_conf;
+
+ pr_debug("%s: stripe: %llu\n", __func__, (unsigned long long)sh->sector);
+
+ /* check if current io_unit is full */
+ if (io && (io->pp_size == entry_space ||
+ io->entries_count == PPL_HDR_MAX_ENTRIES)) {
+ pr_debug("%s: add io_unit blocked by seq: %llu\n",
+ __func__, io->seq);
+ io = NULL;
+ }
+
+ /* add a new unit if there is none or the current is full */
+ if (!io) {
+ io = ppl_new_iounit(log, sh);
+ if (!io)
+ return -ENOMEM;
+ spin_lock_irq(&log->io_list_lock);
+ list_add_tail(&io->log_sibling, &log->io_list);
+ spin_unlock_irq(&log->io_list_lock);
+
+ log->current_io = io;
+ }
+
+ for (i = 0; i < sh->disks; i++) {
+ struct r5dev *dev = &sh->dev[i];
+
+ if (i != sh->pd_idx && test_bit(R5_Wantwrite, &dev->flags)) {
+ if (!data_disks || dev->sector < data_sector)
+ data_sector = dev->sector;
+ data_disks++;
+ }
+ }
+ BUG_ON(!data_disks);
+
+ pr_debug("%s: seq: %llu data_sector: %llu data_disks: %d\n", __func__,
+ io->seq, (unsigned long long)data_sector, data_disks);
+
+ pplhdr = page_address(io->header_page);
+
+ if (io->entries_count > 0) {
+ struct ppl_header_entry *last =
+ &pplhdr->entries[io->entries_count - 1];
+ u64 data_sector_last = le64_to_cpu(last->data_sector);
+ u32 data_size_last = le32_to_cpu(last->data_size);
+ u32 pp_size_last = le32_to_cpu(last->pp_size);
+
+ /*
+ * Check if we can merge with the last entry. Must be on
+ * the same stripe and disks. Use bit shift and logarithm
+ * to avoid 64-bit division.
+ */
+ if ((data_sector >> ilog2(conf->chunk_sectors) ==
+ data_sector_last >> ilog2(conf->chunk_sectors)) &&
+ ((pp_size_last == 0 &&
+ test_bit(STRIPE_FULL_WRITE, &sh->state)) ||
+ ((data_sector_last + (pp_size_last >> 9) == data_sector) &&
+ (data_size_last == pp_size_last * data_disks))))
+ e = last;
+ }
+
+ if (!e) {
+ e = &pplhdr->entries[io->entries_count++];
+ e->data_sector = cpu_to_le64(data_sector);
+ e->parity_disk = cpu_to_le32(sh->pd_idx);
+ e->checksum = cpu_to_le32(~0);
+ }
+
+ le32_add_cpu(&e->data_size, data_disks << PAGE_SHIFT);
+
+ /* don't write any PP if full stripe write */
+ if (!test_bit(STRIPE_FULL_WRITE, &sh->state)) {
+ le32_add_cpu(&e->pp_size, PAGE_SIZE);
+ io->pp_size += PAGE_SIZE;
+ e->checksum = cpu_to_le32(crc32c_le(le32_to_cpu(e->checksum),
+ page_address(sh->ppl_page),
+ PAGE_SIZE));
+ }
+
+ list_add_tail(&sh->log_list, &io->stripe_list);
+ atomic_inc(&io->pending_stripes);
+ sh->ppl_log_io = io;
+
+ return 0;
+}
+
+int ppl_write_stripe(struct ppl_conf *ppl_conf, struct stripe_head *sh)
+{
+ struct ppl_log *log;
+ struct ppl_io_unit *io = sh->ppl_log_io;
+
+ if (io || test_bit(STRIPE_SYNCING, &sh->state) ||
+ !test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags) ||
+ !test_bit(R5_Insync, &sh->dev[sh->pd_idx].flags)) {
+ clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
+ return -EAGAIN;
+ }
+
+ log = &ppl_conf->child_logs[sh->pd_idx];
+
+ mutex_lock(&log->io_mutex);
+
+ if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
+ mutex_unlock(&log->io_mutex);
+ return -EAGAIN;
+ }
+
+ set_bit(STRIPE_LOG_TRAPPED, &sh->state);
+ clear_bit(STRIPE_DELAYED, &sh->state);
+ atomic_inc(&sh->count);
+
+ if (ppl_log_stripe(log, sh)) {
+ spin_lock_irq(&log->io_list_lock);
+ list_add_tail(&sh->log_list, &log->no_mem_stripes);
+ spin_unlock_irq(&log->io_list_lock);
+ }
+
+ mutex_unlock(&log->io_mutex);
+
+ return 0;
+}
+
+static void ppl_log_endio(struct bio *bio)
+{
+ struct ppl_io_unit *io = bio->bi_private;
+ struct ppl_log *log = io->log;
+ struct ppl_conf *ppl_conf = log->ppl_conf;
+ struct stripe_head *sh, *next;
+
+ pr_debug("%s: seq: %llu\n", __func__, io->seq);
+
+ if (bio->bi_error)
+ md_error(ppl_conf->mddev, log->rdev);
+
+ bio_put(bio);
+ mempool_free(io->header_page, ppl_conf->meta_pool);
+
+ list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
+ list_del_init(&sh->log_list);
+
+ set_bit(STRIPE_HANDLE, &sh->state);
+ raid5_release_stripe(sh);
+ }
+}
+
+static void ppl_submit_iounit(struct ppl_io_unit *io)
+{
+ struct ppl_log *log = io->log;
+ struct ppl_conf *ppl_conf = log->ppl_conf;
+ struct r5conf *conf = ppl_conf->mddev->private;
+ struct ppl_header *pplhdr = page_address(io->header_page);
+ struct bio *bio;
+ struct stripe_head *sh;
+ int i;
+ struct bio_list bios = BIO_EMPTY_LIST;
+ char b[BDEVNAME_SIZE];
+
+ bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, ppl_conf->bs);
+ bio->bi_private = io;
+ bio->bi_end_io = ppl_log_endio;
+ bio->bi_opf = REQ_OP_WRITE | REQ_FUA;
+ bio->bi_bdev = log->rdev->bdev;
+ bio->bi_iter.bi_sector = log->rdev->ppl.sector;
+ bio_add_page(bio, io->header_page, PAGE_SIZE, 0);
+ bio_list_add(&bios, bio);
+
+ sh = list_first_entry(&io->stripe_list, struct stripe_head, log_list);
+
+ for (i = 0; i < io->entries_count; i++) {
+ struct ppl_header_entry *e = &pplhdr->entries[i];
+ u32 pp_size = le32_to_cpu(e->pp_size);
+ u32 data_size = le32_to_cpu(e->data_size);
+ u64 data_sector = le64_to_cpu(e->data_sector);
+ int stripes_count;
+
+ if (pp_size > 0)
+ stripes_count = pp_size >> PAGE_SHIFT;
+ else
+ stripes_count = (data_size /
+ (conf->raid_disks -
+ conf->max_degraded)) >> PAGE_SHIFT;
+
+ while (stripes_count--) {
+ /*
+ * if entry without partial parity just skip its stripes
+ * without adding pages to bio
+ */
+ if (pp_size > 0 &&
+ !bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0)) {
+ struct bio *prev = bio;
+
+ bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES,
+ ppl_conf->bs);
+ bio->bi_opf = prev->bi_opf;
+ bio->bi_bdev = prev->bi_bdev;
+ bio->bi_iter.bi_sector = bio_end_sector(prev);
+ bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
+ bio_chain(bio, prev);
+ bio_list_add(&bios, bio);
+ }
+ sh = list_next_entry(sh, log_list);
+ }
+
+ pr_debug("%s: seq: %llu entry: %d data_sector: %llu pp_size: %u data_size: %u\n",
+ __func__, io->seq, i, data_sector, pp_size, data_size);
+
+ e->data_sector = cpu_to_le64(data_sector >>
+ ilog2(ppl_conf->block_size >> 9));
+ e->checksum = cpu_to_le32(~le32_to_cpu(e->checksum));
+ }
+
+ pplhdr->entries_count = cpu_to_le32(io->entries_count);
+ pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PPL_HEADER_SIZE));
+
+ while ((bio = bio_list_pop(&bios))) {
+ pr_debug("%s: seq: %llu submit_bio() size: %u sector: %llu dev: %s\n",
+ __func__, io->seq, bio->bi_iter.bi_size,
+ (unsigned long long)bio->bi_iter.bi_sector,
+ bdevname(bio->bi_bdev, b));
+ submit_bio(bio);
+ }
+}
+
+static void ppl_submit_current_io(struct ppl_log *log)
+{
+ struct ppl_io_unit *io;
+
+ spin_lock_irq(&log->io_list_lock);
+
+ io = list_first_entry_or_null(&log->io_list, struct ppl_io_unit,
+ log_sibling);
+ if (io && io->submitted)
+ io = NULL;
+
+ spin_unlock_irq(&log->io_list_lock);
+
+ if (io) {
+ io->submitted = true;
+
+ if (io == log->current_io)
+ log->current_io = NULL;
+
+ ppl_submit_iounit(io);
+ }
+}
+
+void ppl_write_stripe_run(struct ppl_conf *ppl_conf)
+{
+ struct ppl_log *log;
+ int i;
+
+ for (i = 0; i < ppl_conf->count; i++) {
+ log = &ppl_conf->child_logs[i];
+
+ mutex_lock(&log->io_mutex);
+ ppl_submit_current_io(log);
+ mutex_unlock(&log->io_mutex);
+ }
+}
+
+static void ppl_io_unit_finished(struct ppl_io_unit *io)
+{
+ struct ppl_log *log = io->log;
+ unsigned long flags;
+
+ pr_debug("%s: seq: %llu\n", __func__, io->seq);
+
+ spin_lock_irqsave(&log->io_list_lock, flags);
+
+ list_del(&io->log_sibling);
+ mempool_free(io, log->ppl_conf->io_pool);
+
+ if (!list_empty(&log->no_mem_stripes)) {
+ struct stripe_head *sh = list_first_entry(&log->no_mem_stripes,
+ struct stripe_head,
+ log_list);
+ list_del_init(&sh->log_list);
+ set_bit(STRIPE_HANDLE, &sh->state);
+ raid5_release_stripe(sh);
+ }
+
+ spin_unlock_irqrestore(&log->io_list_lock, flags);
+}
+
+void ppl_stripe_write_finished(struct stripe_head *sh)
+{
+ struct ppl_io_unit *io;
+
+ io = sh->ppl_log_io;
+ sh->ppl_log_io = NULL;
+
+ if (io && atomic_dec_and_test(&io->pending_stripes))
+ ppl_io_unit_finished(io);
+}
+
+void ppl_exit_log(struct ppl_conf *ppl_conf)
+{
+ kfree(ppl_conf->child_logs);
+
+ mempool_destroy(ppl_conf->meta_pool);
+ if (ppl_conf->bs)
+ bioset_free(ppl_conf->bs);
+ mempool_destroy(ppl_conf->io_pool);
+ kmem_cache_destroy(ppl_conf->io_kc);
+
+ kfree(ppl_conf);
+}
+
+static int ppl_validate_rdev(struct md_rdev *rdev)
+{
+ char b[BDEVNAME_SIZE];
+ int ppl_data_sectors;
+ int ppl_size_new;
+
+ /*
+ * The configured PPL size must be enough to store
+ * the header and (at the very least) partial parity
+ * for one stripe. Round it down to ensure the data
+ * space is cleanly divisible by stripe size.
+ */
+ ppl_data_sectors = rdev->ppl.size - (PPL_HEADER_SIZE >> 9);
+
+ if (ppl_data_sectors > 0)
+ ppl_data_sectors = rounddown(ppl_data_sectors, STRIPE_SECTORS);
+
+ if (ppl_data_sectors <= 0) {
+ pr_warn("md/raid:%s: PPL space too small on %s\n",
+ mdname(rdev->mddev), bdevname(rdev->bdev, b));
+ return -ENOSPC;
+ }
+
+ ppl_size_new = ppl_data_sectors + (PPL_HEADER_SIZE >> 9);
+
+ if ((rdev->ppl.sector < rdev->data_offset &&
+ rdev->ppl.sector + ppl_size_new > rdev->data_offset) ||
+ (rdev->ppl.sector >= rdev->data_offset &&
+ rdev->data_offset + rdev->sectors > rdev->ppl.sector)) {
+ pr_warn("md/raid:%s: PPL space overlaps with data on %s\n",
+ mdname(rdev->mddev), bdevname(rdev->bdev, b));
+ return -EINVAL;
+ }
+
+ if (!rdev->mddev->external &&
+ ((rdev->ppl.offset > 0 && rdev->ppl.offset < (rdev->sb_size >> 9)) ||
+ (rdev->ppl.offset <= 0 && rdev->ppl.offset + ppl_size_new > 0))) {
+ pr_warn("md/raid:%s: PPL space overlaps with superblock on %s\n",
+ mdname(rdev->mddev), bdevname(rdev->bdev, b));
+ return -EINVAL;
+ }
+
+ rdev->ppl.size = ppl_size_new;
+
+ return 0;
+}
+
+int ppl_init_log(struct r5conf *conf)
+{
+ struct ppl_conf *ppl_conf;
+ struct mddev *mddev = conf->mddev;
+ int ret = 0;
+ int i;
+ bool need_cache_flush;
+
+ if (PAGE_SIZE != 4096)
+ return -EINVAL;
+
+ if (mddev->bitmap_info.file || mddev->bitmap_info.offset) {
+ pr_warn("md/raid:%s PPL is not compatible with bitmap\n",
+ mdname(mddev));
+ return -EINVAL;
+ }
+
+ if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
+ pr_warn("md/raid:%s PPL is not compatible with journal\n",
+ mdname(mddev));
+ return -EINVAL;
+ }
+
+ ppl_conf = kzalloc(sizeof(struct ppl_conf), GFP_KERNEL);
+ if (!ppl_conf)
+ return -ENOMEM;
+
+ ppl_conf->io_kc = KMEM_CACHE(ppl_io_unit, 0);
+ if (!ppl_conf->io_kc) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ppl_conf->io_pool = mempool_create_slab_pool(conf->raid_disks, ppl_conf->io_kc);
+ if (!ppl_conf->io_pool) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ppl_conf->bs = bioset_create(conf->raid_disks, 0);
+ if (!ppl_conf->bs) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ppl_conf->meta_pool = mempool_create_page_pool(conf->raid_disks, 0);
+ if (!ppl_conf->meta_pool) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ppl_conf->mddev = mddev;
+ ppl_conf->count = conf->raid_disks;
+ ppl_conf->child_logs = kcalloc(ppl_conf->count, sizeof(struct ppl_log),
+ GFP_KERNEL);
+ if (!ppl_conf->child_logs) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ atomic64_set(&ppl_conf->seq, 0);
+
+ if (!mddev->external) {
+ ppl_conf->signature = ~crc32c_le(~0, mddev->uuid, sizeof(mddev->uuid));
+ ppl_conf->block_size = 512;
+ } else {
+ ppl_conf->block_size = queue_logical_block_size(mddev->queue);
+ }
+
+ for (i = 0; i < ppl_conf->count; i++) {
+ struct ppl_log *log = &ppl_conf->child_logs[i];
+ struct md_rdev *rdev = conf->disks[i].rdev;
+
+ mutex_init(&log->io_mutex);
+ spin_lock_init(&log->io_list_lock);
+ INIT_LIST_HEAD(&log->io_list);
+ INIT_LIST_HEAD(&log->no_mem_stripes);
+
+ log->ppl_conf = ppl_conf;
+ log->rdev = rdev;
+
+ if (rdev) {
+ struct request_queue *q;
+
+ ret = ppl_validate_rdev(rdev);
+ if (ret)
+ goto err;
+
+ q = bdev_get_queue(rdev->bdev);
+ if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
+ need_cache_flush = true;
+ }
+ }
+
+ if (need_cache_flush)
+ pr_warn("md/raid:%s: Volatile write-back cache should be disabled on all member drives when using PPL!\n",
+ mdname(mddev));
+
+ conf->ppl = ppl_conf;
+
+ return 0;
+err:
+ ppl_exit_log(ppl_conf);
+ return ret;
+}
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 02e02fe5b04e..21440b594878 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -739,7 +739,7 @@ static bool stripe_can_batch(struct stripe_head *sh)
{
struct r5conf *conf = sh->raid_conf;
- if (conf->log)
+ if (conf->log || conf->ppl)
return false;
return test_bit(STRIPE_BATCH_READY, &sh->state) &&
!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
@@ -936,6 +936,9 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
}
}
+ if (conf->ppl && ppl_write_stripe(conf->ppl, sh) == 0)
+ return;
+
for (i = disks; i--; ) {
int op, op_flags = 0;
int replace_only = 0;
@@ -3308,6 +3311,16 @@ static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
&dd_idx, sh);
}
+static void log_stripe_write_finished(struct stripe_head *sh)
+{
+ struct r5conf *conf = sh->raid_conf;
+
+ if (conf->log)
+ r5l_stripe_write_finished(sh);
+ else if (conf->ppl)
+ ppl_stripe_write_finished(sh);
+}
+
static void
handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
struct stripe_head_state *s, int disks,
@@ -3347,7 +3360,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
if (bi)
bitmap_end = 1;
- r5l_stripe_write_finished(sh);
+ log_stripe_write_finished(sh);
if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
wake_up(&conf->wait_for_overlap);
@@ -3766,7 +3779,7 @@ static void handle_stripe_clean_event(struct r5conf *conf,
discard_pending = 1;
}
- r5l_stripe_write_finished(sh);
+ log_stripe_write_finished(sh);
if (!discard_pending &&
test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
@@ -4756,7 +4769,7 @@ static void handle_stripe(struct stripe_head *sh)
if (s.just_cached)
r5c_handle_cached_data_endio(conf, sh, disks, &s.return_bi);
- r5l_stripe_write_finished(sh);
+ log_stripe_write_finished(sh);
/* Now we might consider reading some blocks, either to check/generate
* parity, or to satisfy requests
@@ -6120,6 +6133,14 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
return handled;
}
+static void log_write_stripe_run(struct r5conf *conf)
+{
+ if (conf->log)
+ r5l_write_stripe_run(conf->log);
+ else if (conf->ppl)
+ ppl_write_stripe_run(conf->ppl);
+}
+
static int handle_active_stripes(struct r5conf *conf, int group,
struct r5worker *worker,
struct list_head *temp_inactive_list)
@@ -6157,7 +6178,7 @@ static int handle_active_stripes(struct r5conf *conf, int group,
for (i = 0; i < batch_size; i++)
handle_stripe(batch[i]);
- r5l_write_stripe_run(conf->log);
+ log_write_stripe_run(conf);
cond_resched();
@@ -6735,6 +6756,8 @@ static void free_conf(struct r5conf *conf)
if (conf->log)
r5l_exit_log(conf->log);
+ if (conf->ppl)
+ ppl_exit_log(conf->ppl);
if (conf->shrinker.nr_deferred)
unregister_shrinker(&conf->shrinker);
@@ -7196,6 +7219,13 @@ static int raid5_run(struct mddev *mddev)
BUG_ON(mddev->delta_disks != 0);
}
+ if (test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
+ test_bit(MD_HAS_PPL, &mddev->flags)) {
+ pr_warn("md/raid:%s: using journal device and PPL not allowed - disabling PPL\n",
+ mdname(mddev));
+ clear_bit(MD_HAS_PPL, &mddev->flags);
+ }
+
if (mddev->private == NULL)
conf = setup_conf(mddev);
else
@@ -7422,6 +7452,11 @@ static int raid5_run(struct mddev *mddev)
mdname(mddev), bdevname(journal_dev->bdev, b));
if (r5l_init_log(conf, journal_dev))
goto abort;
+ } else if (test_bit(MD_HAS_PPL, &mddev->flags)) {
+ pr_debug("md/raid:%s: enabling distributed Partial Parity Log\n",
+ mdname(mddev));
+ if (ppl_init_log(conf))
+ goto abort;
}
return 0;
@@ -7690,7 +7725,7 @@ static int raid5_resize(struct mddev *mddev, sector_t sectors)
sector_t newsize;
struct r5conf *conf = mddev->private;
- if (conf->log)
+ if (conf->log || conf->ppl)
return -EINVAL;
sectors &= ~((sector_t)conf->chunk_sectors - 1);
newsize = raid5_size(mddev, sectors, mddev->raid_disks);
@@ -7743,7 +7778,7 @@ static int check_reshape(struct mddev *mddev)
{
struct r5conf *conf = mddev->private;
- if (conf->log)
+ if (conf->log || conf->ppl)
return -EINVAL;
if (mddev->delta_disks == 0 &&
mddev->new_layout == mddev->layout &&
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 3cc4cb28f7e6..f915a7a0e752 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -230,6 +230,7 @@ struct stripe_head {
struct list_head r5c; /* for r5c_cache->stripe_in_journal */
struct page *ppl_page; /* partial parity of this stripe */
+ struct ppl_io_unit *ppl_log_io;
/**
* struct stripe_operations
* @target - STRIPE_OP_COMPUTE_BLK target
@@ -689,6 +690,7 @@ struct r5conf {
int group_cnt;
int worker_cnt_per_group;
struct r5l_log *log;
+ struct ppl_conf *ppl;
struct bio_list pending_bios;
spinlock_t pending_bios_lock;
@@ -798,4 +800,10 @@ extern void r5c_check_cached_full_stripe(struct r5conf *conf);
extern struct md_sysfs_entry r5c_journal_mode;
extern void r5c_update_on_rdev_error(struct mddev *mddev);
extern bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect);
+
+extern int ppl_init_log(struct r5conf *conf);
+extern void ppl_exit_log(struct ppl_conf *log);
+extern int ppl_write_stripe(struct ppl_conf *log, struct stripe_head *sh);
+extern void ppl_write_stripe_run(struct ppl_conf *log);
+extern void ppl_stripe_write_finished(struct stripe_head *sh);
#endif
diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
index fe2112810c43..2c28711cc5f1 100644
--- a/include/uapi/linux/raid/md_p.h
+++ b/include/uapi/linux/raid/md_p.h
@@ -398,4 +398,30 @@ struct r5l_meta_block {
#define R5LOG_VERSION 0x1
#define R5LOG_MAGIC 0x6433c509
+
+struct ppl_header_entry {
+ __le64 data_sector; /* Raid sector of the new data */
+ __le32 pp_size; /* Length of partial parity */
+ __le32 data_size; /* Length of data */
+ __le32 parity_disk; /* Member disk containing parity */
+ __le32 checksum; /* Checksum of this entry */
+} __attribute__ ((__packed__));
+
+#define PPL_HEADER_SIZE 4096
+#define PPL_HDR_RESERVED 512
+#define PPL_HDR_ENTRY_SPACE \
+ (PPL_HEADER_SIZE - PPL_HDR_RESERVED - 4 * sizeof(u32) - sizeof(u64))
+#define PPL_HDR_MAX_ENTRIES \
+ (PPL_HDR_ENTRY_SPACE / sizeof(struct ppl_header_entry))
+
+struct ppl_header {
+ __u8 reserved[PPL_HDR_RESERVED];/* Reserved space */
+ __le32 signature; /* Signature (family number of volume) */
+ __le32 padding;
+ __le64 generation; /* Generation number of PP Header */
+ __le32 entries_count; /* Number of entries in entry array */
+ __le32 checksum; /* Checksum of PP Header */
+ struct ppl_header_entry entries[PPL_HDR_MAX_ENTRIES];
+} __attribute__ ((__packed__));
+
#endif
--
2.11.0
^ permalink raw reply related [flat|nested] 25+ messages in thread
* [PATCH v4 4/7] md: add sysfs entries for PPL
2017-02-21 19:43 [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
` (2 preceding siblings ...)
2017-02-21 19:43 ` [PATCH v4 3/7] raid5-ppl: Partial Parity Log write logging implementation Artur Paszkiewicz
@ 2017-02-21 19:43 ` Artur Paszkiewicz
2017-02-28 0:37 ` Shaohua Li
2017-02-21 19:43 ` [PATCH v4 5/7] raid5-ppl: load and recover the log Artur Paszkiewicz
` (3 subsequent siblings)
7 siblings, 1 reply; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-02-21 19:43 UTC (permalink / raw)
To: shli; +Cc: linux-raid, Artur Paszkiewicz
Add 'consistency_policy' attribute for array. It indicates how the array
maintains consistency in case of unexpected shutdown.
Add 'ppl_sector' and 'ppl_size' for rdev, which describe the location
and size of the PPL space on the device. They can't be changed for
active members if the array is started and PPL is enabled, so in the
setter functions only basic checks are performed. More checks are done
in ppl_validate_rdev() when starting the log.
These attributes are writable to allow enabling PPL for external
metadata arrays and (later) to enable/disable PPL for a running array.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
---
Documentation/admin-guide/md.rst | 32 ++++++++++-
drivers/md/md.c | 115 +++++++++++++++++++++++++++++++++++++++
2 files changed, 144 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst
index 1e61bf50595c..84de718f24a4 100644
--- a/Documentation/admin-guide/md.rst
+++ b/Documentation/admin-guide/md.rst
@@ -276,14 +276,14 @@ All md devices contain:
array creation it will default to 0, though starting the array as
``clean`` will set it much larger.
- new_dev
+ new_dev
This file can be written but not read. The value written should
be a block device number as major:minor. e.g. 8:0
This will cause that device to be attached to the array, if it is
available. It will then appear at md/dev-XXX (depending on the
name of the device) and further configuration is then possible.
- safe_mode_delay
+ safe_mode_delay
When an md array has seen no write requests for a certain period
of time, it will be marked as ``clean``. When another write
request arrives, the array is marked as ``dirty`` before the write
@@ -292,7 +292,7 @@ All md devices contain:
period as a number of seconds. The default is 200msec (0.200).
Writing a value of 0 disables safemode.
- array_state
+ array_state
This file contains a single word which describes the current
state of the array. In many cases, the state can be set by
writing the word for the desired state, however some states
@@ -401,7 +401,30 @@ All md devices contain:
once the array becomes non-degraded, and this fact has been
recorded in the metadata.
+ consistency_policy
+ This indicates how the array maintains consistency in case of unexpected
+ shutdown. It can be:
+ none
+ Array has no redundancy information, e.g. raid0, linear.
+
+ resync
+ Full resync is performed and all redundancy is regenerated when the
+ array is started after unclean shutdown.
+
+ bitmap
+ Resync assisted by a write-intent bitmap.
+
+ journal
+ For raid4/5/6, journal device is used to log transactions and replay
+ after unclean shutdown.
+
+ ppl
+ For raid5 only, Partial Parity Log is used to close the write hole and
+ eliminate resync.
+
+ The accepted values when writing to this file are ``ppl`` and ``resync``,
+ used to enable and disable PPL.
As component devices are added to an md array, they appear in the ``md``
@@ -563,6 +586,9 @@ Each directory contains:
adds bad blocks without acknowledging them. This is largely
for testing.
+ ppl_sector, ppl_size
+ Location and size (in sectors) of the space used for Partial Parity Log
+ on this device.
An active md device will also contain an entry for each active device
diff --git a/drivers/md/md.c b/drivers/md/md.c
index c2028007b209..3ff979d538d4 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3157,6 +3157,78 @@ static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)
static struct rdev_sysfs_entry rdev_unack_bad_blocks =
__ATTR(unacknowledged_bad_blocks, S_IRUGO|S_IWUSR, ubb_show, ubb_store);
+static ssize_t
+ppl_sector_show(struct md_rdev *rdev, char *page)
+{
+ return sprintf(page, "%llu\n", (unsigned long long)rdev->ppl.sector);
+}
+
+static ssize_t
+ppl_sector_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+ unsigned long long sector;
+
+ if (kstrtoull(buf, 10, §or) < 0)
+ return -EINVAL;
+ if (sector != (sector_t)sector)
+ return -EINVAL;
+
+ if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
+ rdev->raid_disk >= 0)
+ return -EBUSY;
+
+ if (rdev->mddev->persistent) {
+ if (rdev->mddev->major_version == 0)
+ return -EINVAL;
+ if ((sector > rdev->sb_start &&
+ sector - rdev->sb_start > S16_MAX) ||
+ (sector < rdev->sb_start &&
+ rdev->sb_start - sector > -S16_MIN))
+ return -EINVAL;
+ rdev->ppl.offset = sector - rdev->sb_start;
+ } else if (!rdev->mddev->external) {
+ return -EBUSY;
+ }
+ rdev->ppl.sector = sector;
+ return len;
+}
+
+static struct rdev_sysfs_entry rdev_ppl_sector =
+__ATTR(ppl_sector, S_IRUGO|S_IWUSR, ppl_sector_show, ppl_sector_store);
+
+static ssize_t
+ppl_size_show(struct md_rdev *rdev, char *page)
+{
+ return sprintf(page, "%u\n", rdev->ppl.size);
+}
+
+static ssize_t
+ppl_size_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+ unsigned int size;
+
+ if (kstrtouint(buf, 10, &size) < 0)
+ return -EINVAL;
+
+ if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
+ rdev->raid_disk >= 0)
+ return -EBUSY;
+
+ if (rdev->mddev->persistent) {
+ if (rdev->mddev->major_version == 0)
+ return -EINVAL;
+ if (size > U16_MAX)
+ return -EINVAL;
+ } else if (!rdev->mddev->external) {
+ return -EBUSY;
+ }
+ rdev->ppl.size = size;
+ return len;
+}
+
+static struct rdev_sysfs_entry rdev_ppl_size =
+__ATTR(ppl_size, S_IRUGO|S_IWUSR, ppl_size_show, ppl_size_store);
+
static struct attribute *rdev_default_attrs[] = {
&rdev_state.attr,
&rdev_errors.attr,
@@ -3167,6 +3239,8 @@ static struct attribute *rdev_default_attrs[] = {
&rdev_recovery_start.attr,
&rdev_bad_blocks.attr,
&rdev_unack_bad_blocks.attr,
+ &rdev_ppl_sector.attr,
+ &rdev_ppl_size.attr,
NULL,
};
static ssize_t
@@ -4903,6 +4977,46 @@ static struct md_sysfs_entry md_array_size =
__ATTR(array_size, S_IRUGO|S_IWUSR, array_size_show,
array_size_store);
+static ssize_t
+consistency_policy_show(struct mddev *mddev, char *page)
+{
+ int ret;
+
+ if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
+ ret = sprintf(page, "journal\n");
+ } else if (test_bit(MD_HAS_PPL, &mddev->flags)) {
+ ret = sprintf(page, "ppl\n");
+ } else if (mddev->bitmap) {
+ ret = sprintf(page, "bitmap\n");
+ } else if (mddev->pers) {
+ if (mddev->pers->sync_request)
+ ret = sprintf(page, "resync\n");
+ else
+ ret = sprintf(page, "none\n");
+ } else {
+ ret = sprintf(page, "unknown\n");
+ }
+
+ return ret;
+}
+
+static ssize_t
+consistency_policy_store(struct mddev *mddev, const char *buf, size_t len)
+{
+ if (mddev->pers) {
+ return -EBUSY;
+ } else if (mddev->external && strncmp(buf, "ppl", 3) == 0) {
+ set_bit(MD_HAS_PPL, &mddev->flags);
+ return len;
+ } else {
+ return -EINVAL;
+ }
+}
+
+static struct md_sysfs_entry md_consistency_policy =
+__ATTR(consistency_policy, S_IRUGO | S_IWUSR, consistency_policy_show,
+ consistency_policy_store);
+
static struct attribute *md_default_attrs[] = {
&md_level.attr,
&md_layout.attr,
@@ -4918,6 +5032,7 @@ static struct attribute *md_default_attrs[] = {
&md_reshape_direction.attr,
&md_array_size.attr,
&max_corr_read_errors.attr,
+ &md_consistency_policy.attr,
NULL,
};
--
2.11.0
^ permalink raw reply related [flat|nested] 25+ messages in thread
* [PATCH v4 5/7] raid5-ppl: load and recover the log
2017-02-21 19:43 [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
` (3 preceding siblings ...)
2017-02-21 19:43 ` [PATCH v4 4/7] md: add sysfs entries for PPL Artur Paszkiewicz
@ 2017-02-21 19:43 ` Artur Paszkiewicz
2017-02-28 1:12 ` Shaohua Li
2017-02-21 19:44 ` [PATCH v4 6/7] raid5-ppl: support disk hot add/remove with PPL Artur Paszkiewicz
` (2 subsequent siblings)
7 siblings, 1 reply; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-02-21 19:43 UTC (permalink / raw)
To: shli; +Cc: linux-raid, Artur Paszkiewicz
Load the log from each disk when starting the array and recover if the
array is dirty.
The initial empty PPL is written by mdadm. When loading the log we
verify the header checksum and signature. For external metadata arrays
the signature is verified in userspace, so here we read it from the
header, verifying only if it matches on all disks, and use it later when
writing PPL.
In addition to the header checksum, each header entry also contains a
checksum of its partial parity data. If the header is valid, recovery is
performed for each entry until an invalid entry is found. If the array
is not degraded and recovery using PPL fully succeeds, there is no need
to resync the array because data and parity will be consistent, so in
this case resync will be disabled.
Due to compatibility with IMSM implementations on other systems, we
can't assume that the recovery data block size is always 4K. Writes
generated by MD raid5 don't have this issue, but when recovering PPL
written in other environments it is possible to have entries with
512-byte sector granularity. The recovery code takes this into account
and also the logical sector size of the underlying drives.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
---
drivers/md/raid5-ppl.c | 483 +++++++++++++++++++++++++++++++++++++++++++++++++
drivers/md/raid5.c | 5 +-
2 files changed, 487 insertions(+), 1 deletion(-)
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index a00cabf1adf6..a7693353243a 100644
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -16,6 +16,7 @@
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/crc32c.h>
+#include <linux/async_tx.h>
#include <linux/raid/md_p.h>
#include "md.h"
#include "raid5.h"
@@ -84,6 +85,10 @@ struct ppl_conf {
mempool_t *io_pool;
struct bio_set *bs;
mempool_t *meta_pool;
+
+ /* used only for recovery */
+ int recovered_entries;
+ int mismatch_count;
};
struct ppl_log {
@@ -450,6 +455,467 @@ void ppl_stripe_write_finished(struct stripe_head *sh)
ppl_io_unit_finished(io);
}
+static void ppl_xor(int size, struct page *page1, struct page *page2,
+ struct page *page_result)
+{
+ struct async_submit_ctl submit;
+ struct dma_async_tx_descriptor *tx;
+ struct page *xor_srcs[] = { page1, page2 };
+
+ init_async_submit(&submit, ASYNC_TX_ACK|ASYNC_TX_XOR_DROP_DST,
+ NULL, NULL, NULL, NULL);
+ tx = async_xor(page_result, xor_srcs, 0, 2, size, &submit);
+
+ async_tx_quiesce(&tx);
+}
+
+/*
+ * PPL recovery strategy: xor partial parity and data from all modified data
+ * disks within a stripe and write the result as the new stripe parity. If all
+ * stripe data disks are modified (full stripe write), no partial parity is
+ * available, so just xor the data disks.
+ *
+ * Recovery of a PPL entry shall occur only if all modified data disks are
+ * available and read from all of them succeeds.
+ *
+ * A PPL entry applies to a stripe, partial parity size for an entry is at most
+ * the size of the chunk. Examples of possible cases for a single entry:
+ *
+ * case 0: single data disk write:
+ * data0 data1 data2 ppl parity
+ * +--------+--------+--------+ +--------------------+
+ * | ------ | ------ | ------ | +----+ | (no change) |
+ * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
+ * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
+ * | ------ | ------ | ------ | +----+ | (no change) |
+ * +--------+--------+--------+ +--------------------+
+ * pp_size = data_size
+ *
+ * case 1: more than one data disk write:
+ * data0 data1 data2 ppl parity
+ * +--------+--------+--------+ +--------------------+
+ * | ------ | ------ | ------ | +----+ | (no change) |
+ * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
+ * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
+ * | ------ | ------ | ------ | +----+ | (no change) |
+ * +--------+--------+--------+ +--------------------+
+ * pp_size = data_size / modified_data_disks
+ *
+ * case 2: write to all data disks (also full stripe write):
+ * data0 data1 data2 parity
+ * +--------+--------+--------+ +--------------------+
+ * | ------ | ------ | ------ | | (no change) |
+ * | -data- | -data- | -data- | --------> | xor all data |
+ * | ------ | ------ | ------ | --------> | (no change) |
+ * | ------ | ------ | ------ | | (no change) |
+ * +--------+--------+--------+ +--------------------+
+ * pp_size = 0
+ *
+ * The following cases are possible only in other implementations. The recovery
+ * code can handle them, but they are not generated at runtime because they can
+ * be reduced to cases 0, 1 and 2:
+ *
+ * case 3:
+ * data0 data1 data2 ppl parity
+ * +--------+--------+--------+ +----+ +--------------------+
+ * | ------ | -data- | -data- | | pp | | data1 ^ data2 ^ pp |
+ * | ------ | -data- | -data- | | pp | -> | data1 ^ data2 ^ pp |
+ * | -data- | -data- | -data- | | -- | -> | xor all data |
+ * | -data- | -data- | ------ | | pp | | data0 ^ data1 ^ pp |
+ * +--------+--------+--------+ +----+ +--------------------+
+ * pp_size = chunk_size
+ *
+ * case 4:
+ * data0 data1 data2 ppl parity
+ * +--------+--------+--------+ +----+ +--------------------+
+ * | ------ | -data- | ------ | | pp | | data1 ^ pp |
+ * | ------ | ------ | ------ | | -- | -> | (no change) |
+ * | ------ | ------ | ------ | | -- | -> | (no change) |
+ * | -data- | ------ | ------ | | pp | | data0 ^ pp |
+ * +--------+--------+--------+ +----+ +--------------------+
+ * pp_size = chunk_size
+ */
+static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
+ sector_t ppl_sector)
+{
+ struct ppl_conf *ppl_conf = log->ppl_conf;
+ struct mddev *mddev = ppl_conf->mddev;
+ struct r5conf *conf = mddev->private;
+ int block_size = ppl_conf->block_size;
+ struct page *pages;
+ struct page *page1;
+ struct page *page2;
+ sector_t r_sector_first;
+ sector_t r_sector_last;
+ int strip_sectors;
+ int data_disks;
+ int i;
+ int ret = 0;
+ char b[BDEVNAME_SIZE];
+ unsigned int pp_size = le32_to_cpu(e->pp_size);
+ unsigned int data_size = le32_to_cpu(e->data_size);
+
+ r_sector_first = le64_to_cpu(e->data_sector) * (block_size >> 9);
+
+ if ((pp_size >> 9) < conf->chunk_sectors) {
+ if (pp_size > 0) {
+ data_disks = data_size / pp_size;
+ strip_sectors = pp_size >> 9;
+ } else {
+ data_disks = conf->raid_disks - conf->max_degraded;
+ strip_sectors = (data_size >> 9) / data_disks;
+ }
+ r_sector_last = r_sector_first +
+ (data_disks - 1) * conf->chunk_sectors +
+ strip_sectors;
+ } else {
+ data_disks = conf->raid_disks - conf->max_degraded;
+ strip_sectors = conf->chunk_sectors;
+ r_sector_last = r_sector_first + (data_size >> 9);
+ }
+
+ pages = alloc_pages(GFP_KERNEL, 1);
+ if (!pages)
+ return -ENOMEM;
+ page1 = pages;
+ page2 = pages + 1;
+
+ pr_debug("%s: array sector first: %llu last: %llu\n", __func__,
+ (unsigned long long)r_sector_first,
+ (unsigned long long)r_sector_last);
+
+ /* if start and end is 4k aligned, use a 4k block */
+ if (block_size == 512 &&
+ (r_sector_first & (STRIPE_SECTORS - 1)) == 0 &&
+ (r_sector_last & (STRIPE_SECTORS - 1)) == 0)
+ block_size = STRIPE_SIZE;
+
+ /* iterate through blocks in strip */
+ for (i = 0; i < strip_sectors; i += (block_size >> 9)) {
+ bool update_parity = false;
+ sector_t parity_sector;
+ struct md_rdev *parity_rdev;
+ struct stripe_head sh;
+ int disk;
+ int indent = 0;
+
+ pr_debug("%s:%*s iter %d start\n", __func__, indent, "", i);
+ indent += 2;
+
+ memset(page_address(page1), 0, PAGE_SIZE);
+
+ /* iterate through data member disks */
+ for (disk = 0; disk < data_disks; disk++) {
+ int dd_idx;
+ struct md_rdev *rdev;
+ sector_t sector;
+ sector_t r_sector = r_sector_first + i +
+ (disk * conf->chunk_sectors);
+
+ pr_debug("%s:%*s data member disk %d start\n",
+ __func__, indent, "", disk);
+ indent += 2;
+
+ if (r_sector >= r_sector_last) {
+ pr_debug("%s:%*s array sector %llu doesn't need parity update\n",
+ __func__, indent, "",
+ (unsigned long long)r_sector);
+ indent -= 2;
+ continue;
+ }
+
+ update_parity = true;
+
+ /* map raid sector to member disk */
+ sector = raid5_compute_sector(conf, r_sector, 0,
+ &dd_idx, NULL);
+ pr_debug("%s:%*s processing array sector %llu => data member disk %d, sector %llu\n",
+ __func__, indent, "",
+ (unsigned long long)r_sector, dd_idx,
+ (unsigned long long)sector);
+
+ rdev = conf->disks[dd_idx].rdev;
+ if (!rdev) {
+ pr_debug("%s:%*s data member disk %d missing\n",
+ __func__, indent, "", dd_idx);
+ update_parity = false;
+ break;
+ }
+
+ pr_debug("%s:%*s reading data member disk %s sector %llu\n",
+ __func__, indent, "", bdevname(rdev->bdev, b),
+ (unsigned long long)sector);
+ if (!sync_page_io(rdev, sector, block_size, page2,
+ REQ_OP_READ, 0, false)) {
+ md_error(mddev, rdev);
+ pr_debug("%s:%*s read failed!\n", __func__,
+ indent, "");
+ ret = -EIO;
+ goto out;
+ }
+
+ ppl_xor(block_size, page1, page2, page1);
+
+ indent -= 2;
+ }
+
+ if (!update_parity)
+ continue;
+
+ if (pp_size > 0) {
+ pr_debug("%s:%*s reading pp disk sector %llu\n",
+ __func__, indent, "",
+ (unsigned long long)(ppl_sector + i));
+ if (!sync_page_io(log->rdev,
+ ppl_sector - log->rdev->data_offset + i,
+ block_size, page2, REQ_OP_READ, 0,
+ false)) {
+ pr_debug("%s:%*s read failed!\n", __func__,
+ indent, "");
+ md_error(mddev, log->rdev);
+ ret = -EIO;
+ goto out;
+ }
+
+ ppl_xor(block_size, page1, page2, page1);
+ }
+
+ /* map raid sector to parity disk */
+ parity_sector = raid5_compute_sector(conf, r_sector_first + i,
+ 0, &disk, &sh);
+ BUG_ON(sh.pd_idx != le32_to_cpu(e->parity_disk));
+ parity_rdev = conf->disks[sh.pd_idx].rdev;
+
+ BUG_ON(parity_rdev->bdev->bd_dev != log->rdev->bdev->bd_dev);
+ pr_debug("%s:%*s write parity at sector %llu, disk %s\n",
+ __func__, indent, "",
+ (unsigned long long)parity_sector,
+ bdevname(parity_rdev->bdev, b));
+ if (!sync_page_io(parity_rdev, parity_sector, block_size,
+ page1, REQ_OP_WRITE, 0, false)) {
+ pr_debug("%s:%*s parity write error!\n", __func__,
+ indent, "");
+ md_error(mddev, parity_rdev);
+ ret = -EIO;
+ goto out;
+ }
+ }
+out:
+ __free_pages(pages, 1);
+ return ret;
+}
+
+static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr)
+{
+ struct ppl_conf *ppl_conf = log->ppl_conf;
+ struct md_rdev *rdev = log->rdev;
+ struct mddev *mddev = rdev->mddev;
+ sector_t ppl_sector = rdev->ppl.sector + (PPL_HEADER_SIZE >> 9);
+ struct page *page;
+ int i;
+ int ret = 0;
+
+ page = alloc_page(GFP_KERNEL);
+ if (!page)
+ return -ENOMEM;
+
+ /* iterate through all PPL entries saved */
+ for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++) {
+ struct ppl_header_entry *e = &pplhdr->entries[i];
+ u32 pp_size = le32_to_cpu(e->pp_size);
+ sector_t sector = ppl_sector;
+ int ppl_entry_sectors = pp_size >> 9;
+ u32 crc, crc_stored;
+
+ pr_debug("%s: disk: %d entry: %d ppl_sector: %llu pp_size: %u\n",
+ __func__, rdev->raid_disk, i,
+ (unsigned long long)ppl_sector, pp_size);
+
+ crc = ~0;
+ crc_stored = le32_to_cpu(e->checksum);
+
+ /* read parial parity for this entry and calculate its checksum */
+ while (pp_size) {
+ int s = pp_size > PAGE_SIZE ? PAGE_SIZE : pp_size;
+
+ if (!sync_page_io(rdev, sector - rdev->data_offset,
+ s, page, REQ_OP_READ, 0, false)) {
+ md_error(mddev, rdev);
+ ret = -EIO;
+ goto out;
+ }
+
+ crc = crc32c_le(crc, page_address(page), s);
+
+ pp_size -= s;
+ sector += s >> 9;
+ }
+
+ crc = ~crc;
+
+ if (crc != crc_stored) {
+ /*
+ * Don't recover this entry if the checksum does not
+ * match, but keep going and try to recover other
+ * entries.
+ */
+ pr_debug("%s: ppl entry crc does not match: stored: 0x%x calculated: 0x%x\n",
+ __func__, crc_stored, crc);
+ ppl_conf->mismatch_count++;
+ } else {
+ ret = ppl_recover_entry(log, e, ppl_sector);
+ if (ret)
+ goto out;
+ ppl_conf->recovered_entries++;
+ }
+
+ ppl_sector += ppl_entry_sectors;
+ }
+out:
+ __free_page(page);
+ return ret;
+}
+
+static int ppl_write_empty_header(struct ppl_log *log)
+{
+ struct page *page;
+ struct ppl_header *pplhdr;
+ struct md_rdev *rdev = log->rdev;
+ int ret = 0;
+
+ pr_debug("%s: disk: %d ppl_sector: %llu\n", __func__,
+ rdev->raid_disk, (unsigned long long)rdev->ppl.sector);
+
+ page = alloc_page(GFP_NOIO | __GFP_ZERO);
+ if (!page)
+ return -ENOMEM;
+
+ pplhdr = page_address(page);
+ memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
+ pplhdr->signature = cpu_to_le32(log->ppl_conf->signature);
+ pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));
+
+ if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
+ PPL_HEADER_SIZE, page, REQ_OP_WRITE, 0, false)) {
+ md_error(rdev->mddev, rdev);
+ ret = -EIO;
+ }
+
+ __free_page(page);
+ return ret;
+}
+
+static int ppl_load_distributed(struct ppl_log *log)
+{
+ struct ppl_conf *ppl_conf = log->ppl_conf;
+ struct md_rdev *rdev = log->rdev;
+ struct mddev *mddev = rdev->mddev;
+ struct page *page;
+ struct ppl_header *pplhdr;
+ u32 crc, crc_stored;
+ u32 signature;
+ int ret = 0;
+
+ pr_debug("%s: disk: %d\n", __func__, rdev->raid_disk);
+
+ /* read PPL header */
+ page = alloc_page(GFP_KERNEL);
+ if (!page)
+ return -ENOMEM;
+
+ if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
+ PAGE_SIZE, page, REQ_OP_READ, 0, false)) {
+ md_error(mddev, rdev);
+ ret = -EIO;
+ goto out;
+ }
+ pplhdr = page_address(page);
+
+ /* check header validity */
+ crc_stored = le32_to_cpu(pplhdr->checksum);
+ pplhdr->checksum = 0;
+ crc = ~crc32c_le(~0, pplhdr, PAGE_SIZE);
+
+ if (crc_stored != crc) {
+ pr_debug("%s: ppl header crc does not match: stored: 0x%x calculated: 0x%x\n",
+ __func__, crc_stored, crc);
+ ppl_conf->mismatch_count++;
+ goto out;
+ }
+
+ signature = le32_to_cpu(pplhdr->signature);
+
+ if (mddev->external) {
+ /*
+ * For external metadata the header signature is set and
+ * validated in userspace.
+ */
+ ppl_conf->signature = signature;
+ } else if (ppl_conf->signature != signature) {
+ pr_debug("%s: ppl header signature does not match: stored: 0x%x configured: 0x%x\n",
+ __func__, signature, ppl_conf->signature);
+ ppl_conf->mismatch_count++;
+ goto out;
+ }
+
+ /* attempt to recover from log if we are starting a dirty array */
+ if (!mddev->pers && mddev->recovery_cp != MaxSector)
+ ret = ppl_recover(log, pplhdr);
+out:
+ /* write empty header if we are starting the array */
+ if (!ret && !mddev->pers)
+ ret = ppl_write_empty_header(log);
+
+ __free_page(page);
+
+ pr_debug("%s: return: %d mismatch_count: %d recovered_entries: %d\n",
+ __func__, ret, ppl_conf->mismatch_count,
+ ppl_conf->recovered_entries);
+ return ret;
+}
+
+static int ppl_load(struct ppl_conf *ppl_conf)
+{
+ int ret = 0;
+ u32 signature = 0;
+ bool signature_set = false;
+ int i;
+
+ for (i = 0; i < ppl_conf->count; i++) {
+ struct ppl_log *log = &ppl_conf->child_logs[i];
+
+ /* skip missing drive */
+ if (!log->rdev)
+ continue;
+
+ ret = ppl_load_distributed(log);
+ if (ret)
+ break;
+
+ /*
+ * For external metadata we can't check if the signature is
+ * correct on a single drive, but we can check if it is the same
+ * on all drives.
+ */
+ if (ppl_conf->mddev->external) {
+ if (!signature_set) {
+ signature = ppl_conf->signature;
+ signature_set = true;
+ } else if (signature != ppl_conf->signature) {
+ pr_warn("md/raid:%s: PPL header signature does not match on all member drives\n",
+ mdname(ppl_conf->mddev));
+ ret = -EINVAL;
+ break;
+ }
+ }
+ }
+
+ pr_debug("%s: return: %d mismatch_count: %d recovered_entries: %d\n",
+ __func__, ret, ppl_conf->mismatch_count,
+ ppl_conf->recovered_entries);
+ return ret;
+}
+
void ppl_exit_log(struct ppl_conf *ppl_conf)
{
kfree(ppl_conf->child_logs);
@@ -608,6 +1074,23 @@ int ppl_init_log(struct r5conf *conf)
pr_warn("md/raid:%s: Volatile write-back cache should be disabled on all member drives when using PPL!\n",
mdname(mddev));
+ /* load and possibly recover the logs from the member disks */
+ ret = ppl_load(ppl_conf);
+
+ if (ret) {
+ goto err;
+ } else if (!mddev->pers &&
+ mddev->recovery_cp == 0 && !mddev->degraded &&
+ ppl_conf->recovered_entries > 0 &&
+ ppl_conf->mismatch_count == 0) {
+ /*
+ * If we are starting a dirty array and the recovery succeeds
+ * without any issues, set the array as clean.
+ */
+ mddev->recovery_cp = MaxSector;
+ set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
+ }
+
conf->ppl = ppl_conf;
return 0;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 21440b594878..8b52392457d8 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7317,7 +7317,10 @@ static int raid5_run(struct mddev *mddev)
if (mddev->degraded > dirty_parity_disks &&
mddev->recovery_cp != MaxSector) {
- if (mddev->ok_start_degraded)
+ if (test_bit(MD_HAS_PPL, &mddev->flags))
+ pr_crit("md/raid:%s: starting dirty degraded array with PPL.\n",
+ mdname(mddev));
+ else if (mddev->ok_start_degraded)
pr_crit("md/raid:%s: starting dirty degraded array - data corruption possible.\n",
mdname(mddev));
else {
--
2.11.0
^ permalink raw reply related [flat|nested] 25+ messages in thread
* [PATCH v4 6/7] raid5-ppl: support disk hot add/remove with PPL
2017-02-21 19:43 [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
` (4 preceding siblings ...)
2017-02-21 19:43 ` [PATCH v4 5/7] raid5-ppl: load and recover the log Artur Paszkiewicz
@ 2017-02-21 19:44 ` Artur Paszkiewicz
2017-02-28 1:22 ` Shaohua Li
2017-02-21 19:44 ` [PATCH v4 7/7] raid5-ppl: runtime PPL enabling or disabling Artur Paszkiewicz
2017-02-28 1:35 ` [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Shaohua Li
7 siblings, 1 reply; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-02-21 19:44 UTC (permalink / raw)
To: shli; +Cc: linux-raid, Artur Paszkiewicz
Add a function to modify the log by removing an rdev when a drive fails
or adding when a spare/replacement is activated as a raid member.
Removing a disk just clears the child log rdev pointer. No new stripes
will be accepted for this child log in ppl_write_stripe() and running io
units will be processed without writing PPL to the device.
Adding a disk sets the child log rdev pointer and writes an empty PPL
header.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
---
drivers/md/raid5-ppl.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
drivers/md/raid5.c | 15 +++++++++++++++
drivers/md/raid5.h | 8 ++++++++
3 files changed, 70 insertions(+)
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index a7693353243a..c2070d124849 100644
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -319,6 +319,12 @@ static void ppl_submit_iounit(struct ppl_io_unit *io)
bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, ppl_conf->bs);
bio->bi_private = io;
+
+ if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
+ ppl_log_endio(bio);
+ return;
+ }
+
bio->bi_end_io = ppl_log_endio;
bio->bi_opf = REQ_OP_WRITE | REQ_FUA;
bio->bi_bdev = log->rdev->bdev;
@@ -1098,3 +1104,44 @@ int ppl_init_log(struct r5conf *conf)
ppl_exit_log(ppl_conf);
return ret;
}
+
+int ppl_modify_log(struct ppl_conf *ppl_conf, struct md_rdev *rdev,
+ enum ppl_modify_log_operation operation)
+{
+ struct ppl_log *log;
+ int ret = 0;
+ char b[BDEVNAME_SIZE];
+
+ if (!rdev)
+ return -EINVAL;
+
+ pr_debug("%s: disk: %d operation: %s dev: %s\n",
+ __func__, rdev->raid_disk,
+ operation == PPL_MODIFY_LOG_DISK_REMOVE ? "remove" :
+ (operation == PPL_MODIFY_LOG_DISK_ADD ? "add" : "?"),
+ bdevname(rdev->bdev, b));
+
+ if (rdev->raid_disk < 0)
+ return 0;
+
+ if (rdev->raid_disk >= ppl_conf->count)
+ return -ENODEV;
+
+ log = &ppl_conf->child_logs[rdev->raid_disk];
+
+ mutex_lock(&log->io_mutex);
+ if (operation == PPL_MODIFY_LOG_DISK_REMOVE) {
+ log->rdev = NULL;
+ } else if (operation == PPL_MODIFY_LOG_DISK_ADD) {
+ ret = ppl_validate_rdev(rdev);
+ if (!ret) {
+ log->rdev = rdev;
+ ret = ppl_write_empty_header(log);
+ }
+ } else {
+ ret = -EINVAL;
+ }
+ mutex_unlock(&log->io_mutex);
+
+ return ret;
+}
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 8b52392457d8..b17e90f06f19 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7623,6 +7623,12 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
*rdevp = rdev;
}
}
+ if (conf->ppl) {
+ err = ppl_modify_log(conf->ppl, rdev,
+ PPL_MODIFY_LOG_DISK_REMOVE);
+ if (err)
+ goto abort;
+ }
if (p->replacement) {
/* We must have just cleared 'rdev' */
p->rdev = p->replacement;
@@ -7632,6 +7638,10 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
*/
p->replacement = NULL;
clear_bit(WantReplacement, &rdev->flags);
+
+ if (conf->ppl)
+ err = ppl_modify_log(conf->ppl, p->rdev,
+ PPL_MODIFY_LOG_DISK_ADD);
} else
/* We might have just removed the Replacement as faulty-
* clear the bit just in case
@@ -7695,6 +7705,11 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
if (rdev->saved_raid_disk != disk)
conf->fullsync = 1;
rcu_assign_pointer(p->rdev, rdev);
+
+ if (conf->ppl)
+ err = ppl_modify_log(conf->ppl, rdev,
+ PPL_MODIFY_LOG_DISK_ADD);
+
goto out;
}
}
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index f915a7a0e752..43cfa5fa71b3 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -806,4 +806,12 @@ extern void ppl_exit_log(struct ppl_conf *log);
extern int ppl_write_stripe(struct ppl_conf *log, struct stripe_head *sh);
extern void ppl_write_stripe_run(struct ppl_conf *log);
extern void ppl_stripe_write_finished(struct stripe_head *sh);
+
+enum ppl_modify_log_operation {
+ PPL_MODIFY_LOG_DISK_REMOVE,
+ PPL_MODIFY_LOG_DISK_ADD,
+};
+extern int ppl_modify_log(struct ppl_conf *log, struct md_rdev *rdev,
+ enum ppl_modify_log_operation operation);
+
#endif
--
2.11.0
^ permalink raw reply related [flat|nested] 25+ messages in thread
* [PATCH v4 7/7] raid5-ppl: runtime PPL enabling or disabling
2017-02-21 19:43 [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
` (5 preceding siblings ...)
2017-02-21 19:44 ` [PATCH v4 6/7] raid5-ppl: support disk hot add/remove with PPL Artur Paszkiewicz
@ 2017-02-21 19:44 ` Artur Paszkiewicz
2017-02-28 1:31 ` Shaohua Li
2017-02-28 1:35 ` [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Shaohua Li
7 siblings, 1 reply; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-02-21 19:44 UTC (permalink / raw)
To: shli; +Cc: linux-raid, Artur Paszkiewicz
Allow writing to 'consistency_policy' attribute when the array is
active. Add a new function 'change_consistency_policy' to the
md_personality operations structure to handle the change in the
personality code. Values "ppl" and "resync" are accepted and
turn PPL on and off respectively.
When enabling PPL its location and size should first be set using
'ppl_sector' and 'ppl_size' attributes and a valid PPL header should be
written at this location on each member device.
Enabling or disabling PPL is performed under a suspended array. The
raid5_reset_stripe_cache function frees the stripe cache and allocates
it again in order to allocate or free the ppl_pages for the stripes in
the stripe cache.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
---
drivers/md/md.c | 12 ++++++++---
drivers/md/md.h | 2 ++
drivers/md/raid5-ppl.c | 4 ++++
drivers/md/raid5.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 73 insertions(+), 3 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 3ff979d538d4..b70e19513588 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5003,14 +5003,20 @@ consistency_policy_show(struct mddev *mddev, char *page)
static ssize_t
consistency_policy_store(struct mddev *mddev, const char *buf, size_t len)
{
+ int err = 0;
+
if (mddev->pers) {
- return -EBUSY;
+ if (mddev->pers->change_consistency_policy)
+ err = mddev->pers->change_consistency_policy(mddev, buf);
+ else
+ err = -EBUSY;
} else if (mddev->external && strncmp(buf, "ppl", 3) == 0) {
set_bit(MD_HAS_PPL, &mddev->flags);
- return len;
} else {
- return -EINVAL;
+ err = -EINVAL;
}
+
+ return err ? err : len;
}
static struct md_sysfs_entry md_consistency_policy =
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 66a5a16e79f7..88a5155c152e 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -548,6 +548,8 @@ struct md_personality
/* congested implements bdi.congested_fn().
* Will not be called while array is 'suspended' */
int (*congested)(struct mddev *mddev, int bits);
+ /* Changes the consistency policy of an active array. */
+ int (*change_consistency_policy)(struct mddev *mddev, const char *buf);
};
struct md_sysfs_entry {
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index c2070d124849..a5c4d3333bce 100644
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -1095,6 +1095,10 @@ int ppl_init_log(struct r5conf *conf)
*/
mddev->recovery_cp = MaxSector;
set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
+ } else if (mddev->pers && ppl_conf->mismatch_count > 0) {
+ /* no mismatch allowed when enabling PPL for a running array */
+ ret = -EINVAL;
+ goto err;
}
conf->ppl = ppl_conf;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index b17e90f06f19..754fb8e1c76f 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -8319,6 +8319,63 @@ static void *raid6_takeover(struct mddev *mddev)
return setup_conf(mddev);
}
+static void raid5_reset_stripe_cache(struct mddev *mddev)
+{
+ struct r5conf *conf = mddev->private;
+
+ mutex_lock(&conf->cache_size_mutex);
+ while (conf->max_nr_stripes &&
+ drop_one_stripe(conf))
+ ;
+ while (conf->min_nr_stripes > conf->max_nr_stripes &&
+ grow_one_stripe(conf, GFP_KERNEL))
+ ;
+ mutex_unlock(&conf->cache_size_mutex);
+}
+
+static int raid5_change_consistency_policy(struct mddev *mddev, const char *buf)
+{
+ struct r5conf *conf;
+ int err;
+
+ err = mddev_lock(mddev);
+ if (err)
+ return err;
+ conf = mddev->private;
+ if (!conf) {
+ mddev_unlock(mddev);
+ return -ENODEV;
+ }
+
+ if (strncmp(buf, "ppl", 3) == 0 &&
+ !test_bit(MD_HAS_PPL, &mddev->flags)) {
+ mddev_suspend(mddev);
+ err = ppl_init_log(conf);
+ if (!err) {
+ set_bit(MD_HAS_PPL, &mddev->flags);
+ raid5_reset_stripe_cache(mddev);
+ }
+ mddev_resume(mddev);
+ } else if (strncmp(buf, "resync", 6) == 0 &&
+ test_bit(MD_HAS_PPL, &mddev->flags)) {
+ mddev_suspend(mddev);
+ ppl_exit_log(conf->ppl);
+ conf->ppl = NULL;
+ clear_bit(MD_HAS_PPL, &mddev->flags);
+ raid5_reset_stripe_cache(mddev);
+ mddev_resume(mddev);
+ } else {
+ err = -EINVAL;
+ }
+
+ if (!err)
+ md_update_sb(mddev, 1);
+
+ mddev_unlock(mddev);
+
+ return err;
+}
+
static struct md_personality raid6_personality =
{
.name = "raid6",
@@ -8364,6 +8421,7 @@ static struct md_personality raid5_personality =
.quiesce = raid5_quiesce,
.takeover = raid5_takeover,
.congested = raid5_congested,
+ .change_consistency_policy = raid5_change_consistency_policy,
};
static struct md_personality raid4_personality =
--
2.11.0
^ permalink raw reply related [flat|nested] 25+ messages in thread
* Re: [PATCH v4 2/7] raid5: calculate partial parity for a stripe
2017-02-21 19:43 ` [PATCH v4 2/7] raid5: calculate partial parity for a stripe Artur Paszkiewicz
@ 2017-02-27 23:45 ` Shaohua Li
2017-03-01 16:12 ` Artur Paszkiewicz
0 siblings, 1 reply; 25+ messages in thread
From: Shaohua Li @ 2017-02-27 23:45 UTC (permalink / raw)
To: Artur Paszkiewicz; +Cc: shli, linux-raid
On Tue, Feb 21, 2017 at 08:43:56PM +0100, Artur Paszkiewicz wrote:
> Attach a page for holding the partial parity data to stripe_head.
> Allocate it only if mddev has the MD_HAS_PPL flag set.
>
> Partial parity is the xor of not modified data chunks of a stripe and is
> calculated as follows:
>
> - reconstruct-write case:
> xor data from all not updated disks in a stripe
>
> - read-modify-write case:
> xor old data and parity from all updated disks in a stripe
>
> Implement it using the async_tx API and integrate into raid_run_ops().
> It must be called when we still have access to old data, so do it when
> STRIPE_OP_BIODRAIN is set, but before ops_run_prexor5(). The result is
> stored into sh->ppl_page.
>
> Partial parity is not meaningful for full stripe write and is not stored
> in the log or used for recovery, so don't attempt to calculate it when
> stripe has STRIPE_FULL_WRITE.
>
> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
> ---
> drivers/md/raid5.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> drivers/md/raid5.h | 3 ++
> 2 files changed, 103 insertions(+)
>
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 7b7722bb2e8d..02e02fe5b04e 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -463,6 +463,11 @@ static void shrink_buffers(struct stripe_head *sh)
> sh->dev[i].page = NULL;
> put_page(p);
> }
> +
> + if (sh->ppl_page) {
> + put_page(sh->ppl_page);
> + sh->ppl_page = NULL;
> + }
> }
>
> static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
> @@ -479,6 +484,13 @@ static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
> sh->dev[i].page = page;
> sh->dev[i].orig_page = page;
> }
> +
> + if (test_bit(MD_HAS_PPL, &sh->raid_conf->mddev->flags)) {
> + sh->ppl_page = alloc_page(gfp);
> + if (!sh->ppl_page)
> + return 1;
> + }
> +
> return 0;
> }
>
> @@ -1974,6 +1986,55 @@ static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu
> &sh->ops.zero_sum_result, percpu->spare_page, &submit);
> }
>
> +static struct dma_async_tx_descriptor *
> +ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
> + struct dma_async_tx_descriptor *tx)
> +{
> + int disks = sh->disks;
> + struct page **xor_srcs = flex_array_get(percpu->scribble, 0);
> + int count = 0, pd_idx = sh->pd_idx, i;
> + struct async_submit_ctl submit;
> +
> + pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
> +
> + /*
> + * Partial parity is the XOR of stripe data chunks that are not changed
> + * during the write request. Depending on available data
> + * (read-modify-write vs. reconstruct-write case) we calculate it
> + * differently.
> + */
> + if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
> + /* rmw: xor old data and parity from updated disks */
> + for (i = disks; i--;) {
> + struct r5dev *dev = &sh->dev[i];
> + if (test_bit(R5_Wantdrain, &dev->flags) || i == pd_idx)
> + xor_srcs[count++] = dev->page;
> + }
> + } else if (sh->reconstruct_state == reconstruct_state_drain_run) {
> + /* rcw: xor data from all not updated disks */
> + for (i = disks; i--;) {
> + struct r5dev *dev = &sh->dev[i];
> + if (test_bit(R5_UPTODATE, &dev->flags))
> + xor_srcs[count++] = dev->page;
> + }
> + } else {
> + return tx;
> + }
> +
> + init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, tx, NULL, sh,
> + flex_array_get(percpu->scribble, 0)
> + + sizeof(struct page *) * (sh->disks + 2));
> +
> + if (count == 1)
> + tx = async_memcpy(sh->ppl_page, xor_srcs[0], 0, 0, PAGE_SIZE,
> + &submit);
> + else
> + tx = async_xor(sh->ppl_page, xor_srcs, 0, count, PAGE_SIZE,
> + &submit);
> +
> + return tx;
> +}
Can you put this function to raid5-ppl.c? I'd like to keep all the log related
out raid5.c if possible.
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 3/7] raid5-ppl: Partial Parity Log write logging implementation
2017-02-21 19:43 ` [PATCH v4 3/7] raid5-ppl: Partial Parity Log write logging implementation Artur Paszkiewicz
@ 2017-02-28 0:04 ` Shaohua Li
2017-03-01 16:13 ` Artur Paszkiewicz
0 siblings, 1 reply; 25+ messages in thread
From: Shaohua Li @ 2017-02-28 0:04 UTC (permalink / raw)
To: Artur Paszkiewicz; +Cc: shli, linux-raid
On Tue, Feb 21, 2017 at 08:43:57PM +0100, Artur Paszkiewicz wrote:
> This implements the PPL write logging functionality. The description
> of PPL is added to the documentation. More details can be found in the
> comments in raid5-ppl.c.
>
> Put the PPL metadata structures to md_p.h because userspace tools
> (mdadm) will also need to read/write PPL.
>
> Warn about using PPL with enabled disk volatile write-back cache for
> now. It can be removed once disk cache flushing before writing PPL is
> implemented.
>
> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
> ---
> Documentation/md/raid5-ppl.txt | 44 +++
> drivers/md/Makefile | 2 +-
> drivers/md/raid5-ppl.c | 617 +++++++++++++++++++++++++++++++++++++++++
> drivers/md/raid5.c | 49 +++-
> drivers/md/raid5.h | 8 +
> include/uapi/linux/raid/md_p.h | 26 ++
> 6 files changed, 738 insertions(+), 8 deletions(-)
> create mode 100644 Documentation/md/raid5-ppl.txt
> create mode 100644 drivers/md/raid5-ppl.c
>
> diff --git a/Documentation/md/raid5-ppl.txt b/Documentation/md/raid5-ppl.txt
> new file mode 100644
> index 000000000000..127072b09363
> --- /dev/null
> +++ b/Documentation/md/raid5-ppl.txt
> @@ -0,0 +1,44 @@
> +Partial Parity Log
> +
> +Partial Parity Log (PPL) is a feature available for RAID5 arrays. The issue
> +addressed by PPL is that after a dirty shutdown, parity of a particular stripe
> +may become inconsistent with data on other member disks. If the array is also
> +in degraded state, there is no way to recalculate parity, because one of the
> +disks is missing. This can lead to silent data corruption when rebuilding the
> +array or using it is as degraded - data calculated from parity for array blocks
> +that have not been touched by a write request during the unclean shutdown can
> +be incorrect. Such condition is known as the RAID5 Write Hole. Because of
> +this, md by default does not allow starting a dirty degraded array.
> +
> +Partial parity for a write operation is the XOR of stripe data chunks not
> +modified by this write. It is just enough data needed for recovering from the
> +write hole. XORing partial parity with the modified chunks produces parity for
> +the stripe, consistent with its state before the write operation, regardless of
> +which chunk writes have completed. If one of the not modified data disks of
> +this stripe is missing, this updated parity can be used to recover its
> +contents. PPL recovery is also performed when starting an array after an
> +unclean shutdown and all disks are available, eliminating the need to resync
> +the array. Because of this, using write-intent bitmap and PPL together is not
> +supported.
> +
> +When handling a write request PPL writes partial parity before new data and
> +parity are dispatched to disks. PPL is a distributed log - it is stored on
> +array member drives in the metadata area, on the parity drive of a particular
> +stripe. It does not require a dedicated journaling drive. Write performance is
> +reduced by up to 30%-40% but it scales with the number of drives in the array
> +and the journaling drive does not become a bottleneck or a single point of
> +failure.
> +
> +Unlike raid5-cache, the other solution in md for closing the write hole, PPL is
> +not a true journal. It does not protect from losing in-flight data, only from
> +silent data corruption. If a dirty disk of a stripe is lost, no PPL recovery is
> +performed for this stripe (parity is not updated). So it is possible to have
> +arbitrary data in the written part of a stripe if that disk is lost. In such
> +case the behavior is the same as in plain raid5.
> +
> +PPL is available for md version-1 metadata and external (specifically IMSM)
> +metadata arrays. It can be enabled using mdadm option --consistency-policy=ppl.
> +
> +Currently, volatile write-back cache should be disabled on all member drives
> +when using PPL. Otherwise it cannot guarantee consistency in case of power
> +failure.
> diff --git a/drivers/md/Makefile b/drivers/md/Makefile
> index 3cbda1af87a0..4d48714ccc6b 100644
> --- a/drivers/md/Makefile
> +++ b/drivers/md/Makefile
> @@ -18,7 +18,7 @@ dm-cache-cleaner-y += dm-cache-policy-cleaner.o
> dm-era-y += dm-era-target.o
> dm-verity-y += dm-verity-target.o
> md-mod-y += md.o bitmap.o
> -raid456-y += raid5.o raid5-cache.o
> +raid456-y += raid5.o raid5-cache.o raid5-ppl.o
>
> # Note: link order is important. All raid personalities
> # and must come before md.o, as they each initialise
> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
> new file mode 100644
> index 000000000000..a00cabf1adf6
> --- /dev/null
> +++ b/drivers/md/raid5-ppl.c
> @@ -0,0 +1,617 @@
> +/*
> + * Partial Parity Log for closing the RAID5 write hole
> + * Copyright (c) 2017, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/blkdev.h>
> +#include <linux/slab.h>
> +#include <linux/crc32c.h>
> +#include <linux/raid/md_p.h>
> +#include "md.h"
> +#include "raid5.h"
> +
> +/*
> + * PPL consists of a 4KB header (struct ppl_header) and at least 128KB for
> + * partial parity data. The header contains an array of entries
> + * (struct ppl_header_entry) which describe the logged write requests.
> + * Partial parity for the entries comes after the header, written in the same
> + * sequence as the entries:
> + *
> + * Header
> + * entry0
> + * ...
> + * entryN
> + * PP data
> + * PP for entry0
> + * ...
> + * PP for entryN
> + *
> + * Every entry holds a checksum of its partial parity, the header also has a
> + * checksum of the header itself. Entries for full stripes writes contain no
> + * partial parity, they only mark the stripes for which parity should be
> + * recalculated after an unclean shutdown.
Please describe the disk format in details. I had trouble to understand
ppl_log_stripe() and ppl_submit_iounit(), things like the ppl merge, full
stripes handling.
> + *
> + * A write request is always logged to the PPL instance stored on the parity
> + * disk of the corresponding stripe. For each member disk there is one ppl_log
> + * used to handle logging for this disk, independently from others. They are
> + * grouped in child_logs array in struct ppl_conf, which is assigned to
> + * r5conf->ppl and used in raid5 core.
> + *
> + * ppl_io_unit represents a full PPL write, header_page contains the ppl_header.
> + * PPL entries for logged stripes are added in ppl_log_stripe(). A stripe can
> + * be appended to the last entry if the chunks to write are the same, otherwise
> + * a new entry is added. Checksums of entries are calculated incrementally as
> + * stripes containing partial parity are being added to entries.
> + * ppl_submit_iounit() calculates the checksum of the header and submits a bio
> + * containing the header page and partial parity pages (sh->ppl_page) for all
> + * stripes of the io_unit. When the PPL write completes, the stripes associated
> + * with the io_unit are released and raid5d starts writing their data and
> + * parity. When all stripes are written, the io_unit is freed and the next can
> + * be submitted.
> + *
> + * An io_unit is used to gather stripes until it is submitted or becomes full
> + * (if the maximum number of entries or size of PPL is reached). Another io_unit
> + * can't be submitted until the previous has completed (PPL and stripe
> + * data+parity is written). The log->io_list tracks all io_units of a log
> + * (for a single member disk). New io_units are added to the end of the list
> + * and the first io_unit is submitted, if it is not submitted already.
> + * The current io_unit accepting new stripes is always at the end of the list.
> + */
> +
> +struct ppl_conf {
> + struct mddev *mddev;
> +
> + /* array of child logs, one for each raid disk */
> + struct ppl_log *child_logs;
> + int count;
> +
> + int block_size; /* the logical block size used for data_sector
> + * in ppl_header_entry */
> + u32 signature; /* raid array identifier */
> + atomic64_t seq; /* current log write sequence number */
> +
> + struct kmem_cache *io_kc;
> + mempool_t *io_pool;
> + struct bio_set *bs;
> + mempool_t *meta_pool;
> +};
> +
> +struct ppl_log {
> + struct ppl_conf *ppl_conf; /* shared between all log instances */
> +
> + struct md_rdev *rdev; /* array member disk associated with
> + * this log instance */
> + struct mutex io_mutex;
> + struct ppl_io_unit *current_io; /* current io_unit accepting new data
> + * always at the end of io_list */
> + spinlock_t io_list_lock;
> + struct list_head io_list; /* all io_units of this log */
> + struct list_head no_mem_stripes;/* stripes to retry if failed to
> + * allocate io_unit */
> +};
> +
> +struct ppl_io_unit {
> + struct ppl_log *log;
> +
> + struct page *header_page; /* for ppl_header */
> +
> + unsigned int entries_count; /* number of entries in ppl_header */
> + unsigned int pp_size; /* total size current of partial parity */
> +
> + u64 seq; /* sequence number of this log write */
> + struct list_head log_sibling; /* log->io_list */
> +
> + struct list_head stripe_list; /* stripes added to the io_unit */
> + atomic_t pending_stripes; /* how many stripes not written to raid */
> +
> + bool submitted; /* true if write to log started */
> +};
> +
> +static struct ppl_io_unit *ppl_new_iounit(struct ppl_log *log,
> + struct stripe_head *sh)
> +{
> + struct ppl_conf *ppl_conf = log->ppl_conf;
> + struct ppl_io_unit *io;
> + struct ppl_header *pplhdr;
> +
> + io = mempool_alloc(ppl_conf->io_pool, GFP_ATOMIC);
> + if (!io)
> + return NULL;
> +
> + memset(io, 0, sizeof(*io));
> + io->log = log;
> + INIT_LIST_HEAD(&io->log_sibling);
> + INIT_LIST_HEAD(&io->stripe_list);
> + atomic_set(&io->pending_stripes, 0);
> +
> + io->header_page = mempool_alloc(ppl_conf->meta_pool, GFP_NOIO);
> + pplhdr = page_address(io->header_page);
> + clear_page(pplhdr);
> + memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
> + pplhdr->signature = cpu_to_le32(ppl_conf->signature);
> +
> + io->seq = atomic64_add_return(1, &ppl_conf->seq);
> + pplhdr->generation = cpu_to_le64(io->seq);
> +
> + return io;
> +}
> +
> +static int ppl_log_stripe(struct ppl_log *log, struct stripe_head *sh)
> +{
> + struct ppl_io_unit *io = log->current_io;
> + struct ppl_header_entry *e = NULL;
> + struct ppl_header *pplhdr;
> + int i;
> + sector_t data_sector = 0;
> + int data_disks = 0;
> + unsigned int entry_space = (log->rdev->ppl.size << 9) - PPL_HEADER_SIZE;
> + struct r5conf *conf = sh->raid_conf;
> +
> + pr_debug("%s: stripe: %llu\n", __func__, (unsigned long long)sh->sector);
> +
> + /* check if current io_unit is full */
> + if (io && (io->pp_size == entry_space ||
> + io->entries_count == PPL_HDR_MAX_ENTRIES)) {
> + pr_debug("%s: add io_unit blocked by seq: %llu\n",
> + __func__, io->seq);
> + io = NULL;
> + }
> +
> + /* add a new unit if there is none or the current is full */
> + if (!io) {
> + io = ppl_new_iounit(log, sh);
> + if (!io)
> + return -ENOMEM;
> + spin_lock_irq(&log->io_list_lock);
> + list_add_tail(&io->log_sibling, &log->io_list);
> + spin_unlock_irq(&log->io_list_lock);
> +
> + log->current_io = io;
> + }
> +
> + for (i = 0; i < sh->disks; i++) {
> + struct r5dev *dev = &sh->dev[i];
> +
> + if (i != sh->pd_idx && test_bit(R5_Wantwrite, &dev->flags)) {
> + if (!data_disks || dev->sector < data_sector)
> + data_sector = dev->sector;
> + data_disks++;
> + }
> + }
> + BUG_ON(!data_disks);
> +
> + pr_debug("%s: seq: %llu data_sector: %llu data_disks: %d\n", __func__,
> + io->seq, (unsigned long long)data_sector, data_disks);
> +
> + pplhdr = page_address(io->header_page);
> +
> + if (io->entries_count > 0) {
> + struct ppl_header_entry *last =
> + &pplhdr->entries[io->entries_count - 1];
> + u64 data_sector_last = le64_to_cpu(last->data_sector);
> + u32 data_size_last = le32_to_cpu(last->data_size);
> + u32 pp_size_last = le32_to_cpu(last->pp_size);
> +
> + /*
> + * Check if we can merge with the last entry. Must be on
> + * the same stripe and disks. Use bit shift and logarithm
> + * to avoid 64-bit division.
> + */
> + if ((data_sector >> ilog2(conf->chunk_sectors) ==
> + data_sector_last >> ilog2(conf->chunk_sectors)) &&
> + ((pp_size_last == 0 &&
> + test_bit(STRIPE_FULL_WRITE, &sh->state)) ||
> + ((data_sector_last + (pp_size_last >> 9) == data_sector) &&
> + (data_size_last == pp_size_last * data_disks))))
please explain this part
> + e = last;
> + }
> +
> + if (!e) {
> + e = &pplhdr->entries[io->entries_count++];
> + e->data_sector = cpu_to_le64(data_sector);
Don't really understand what's the data_sector for. Should this be stripe->sector?
> + e->parity_disk = cpu_to_le32(sh->pd_idx);
> + e->checksum = cpu_to_le32(~0);
> + }
> +
> + le32_add_cpu(&e->data_size, data_disks << PAGE_SHIFT);
> +
> + /* don't write any PP if full stripe write */
> + if (!test_bit(STRIPE_FULL_WRITE, &sh->state)) {
> + le32_add_cpu(&e->pp_size, PAGE_SIZE);
> + io->pp_size += PAGE_SIZE;
> + e->checksum = cpu_to_le32(crc32c_le(le32_to_cpu(e->checksum),
> + page_address(sh->ppl_page),
> + PAGE_SIZE));
> + }
> +
> + list_add_tail(&sh->log_list, &io->stripe_list);
> + atomic_inc(&io->pending_stripes);
> + sh->ppl_log_io = io;
> +
> + return 0;
> +}
> +
> +int ppl_write_stripe(struct ppl_conf *ppl_conf, struct stripe_head *sh)
> +{
> + struct ppl_log *log;
> + struct ppl_io_unit *io = sh->ppl_log_io;
> +
> + if (io || test_bit(STRIPE_SYNCING, &sh->state) ||
> + !test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags) ||
> + !test_bit(R5_Insync, &sh->dev[sh->pd_idx].flags)) {
> + clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
> + return -EAGAIN;
> + }
> +
> + log = &ppl_conf->child_logs[sh->pd_idx];
> +
> + mutex_lock(&log->io_mutex);
> +
> + if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
is the log->rdev check required?
> + mutex_unlock(&log->io_mutex);
> + return -EAGAIN;
> + }
> +
> + set_bit(STRIPE_LOG_TRAPPED, &sh->state);
> + clear_bit(STRIPE_DELAYED, &sh->state);
> + atomic_inc(&sh->count);
> +
> + if (ppl_log_stripe(log, sh)) {
> + spin_lock_irq(&log->io_list_lock);
> + list_add_tail(&sh->log_list, &log->no_mem_stripes);
> + spin_unlock_irq(&log->io_list_lock);
> + }
> +
> + mutex_unlock(&log->io_mutex);
> +
> + return 0;
> +}
> +
> +static void ppl_log_endio(struct bio *bio)
> +{
> + struct ppl_io_unit *io = bio->bi_private;
> + struct ppl_log *log = io->log;
> + struct ppl_conf *ppl_conf = log->ppl_conf;
> + struct stripe_head *sh, *next;
> +
> + pr_debug("%s: seq: %llu\n", __func__, io->seq);
> +
> + if (bio->bi_error)
> + md_error(ppl_conf->mddev, log->rdev);
> +
> + bio_put(bio);
> + mempool_free(io->header_page, ppl_conf->meta_pool);
> +
> + list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
> + list_del_init(&sh->log_list);
> +
> + set_bit(STRIPE_HANDLE, &sh->state);
> + raid5_release_stripe(sh);
> + }
> +}
> +
> +static void ppl_submit_iounit(struct ppl_io_unit *io)
> +{
> + struct ppl_log *log = io->log;
> + struct ppl_conf *ppl_conf = log->ppl_conf;
> + struct r5conf *conf = ppl_conf->mddev->private;
> + struct ppl_header *pplhdr = page_address(io->header_page);
> + struct bio *bio;
> + struct stripe_head *sh;
> + int i;
> + struct bio_list bios = BIO_EMPTY_LIST;
> + char b[BDEVNAME_SIZE];
> +
> + bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, ppl_conf->bs);
> + bio->bi_private = io;
> + bio->bi_end_io = ppl_log_endio;
> + bio->bi_opf = REQ_OP_WRITE | REQ_FUA;
> + bio->bi_bdev = log->rdev->bdev;
> + bio->bi_iter.bi_sector = log->rdev->ppl.sector;
> + bio_add_page(bio, io->header_page, PAGE_SIZE, 0);
> + bio_list_add(&bios, bio);
> +
> + sh = list_first_entry(&io->stripe_list, struct stripe_head, log_list);
> +
> + for (i = 0; i < io->entries_count; i++) {
> + struct ppl_header_entry *e = &pplhdr->entries[i];
> + u32 pp_size = le32_to_cpu(e->pp_size);
> + u32 data_size = le32_to_cpu(e->data_size);
> + u64 data_sector = le64_to_cpu(e->data_sector);
> + int stripes_count;
> +
> + if (pp_size > 0)
> + stripes_count = pp_size >> PAGE_SHIFT;
> + else
> + stripes_count = (data_size /
> + (conf->raid_disks -
> + conf->max_degraded)) >> PAGE_SHIFT;
please explain this part
> +
> + while (stripes_count--) {
> + /*
> + * if entry without partial parity just skip its stripes
> + * without adding pages to bio
> + */
> + if (pp_size > 0 &&
> + !bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0)) {
> + struct bio *prev = bio;
> +
> + bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES,
> + ppl_conf->bs);
The code keeps allocating bios but doesn't dispatch any yet. The bioset can't
guarantee the allocation successes. To have the guarantee, we must make sure
previous bios could finish.
> + bio->bi_opf = prev->bi_opf;
> + bio->bi_bdev = prev->bi_bdev;
> + bio->bi_iter.bi_sector = bio_end_sector(prev);
> + bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
> + bio_chain(bio, prev);
> + bio_list_add(&bios, bio);
> + }
> + sh = list_next_entry(sh, log_list);
> + }
> +
> + pr_debug("%s: seq: %llu entry: %d data_sector: %llu pp_size: %u data_size: %u\n",
> + __func__, io->seq, i, data_sector, pp_size, data_size);
> +
> + e->data_sector = cpu_to_le64(data_sector >>
> + ilog2(ppl_conf->block_size >> 9));
> + e->checksum = cpu_to_le32(~le32_to_cpu(e->checksum));
> + }
> +
> + pplhdr->entries_count = cpu_to_le32(io->entries_count);
> + pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PPL_HEADER_SIZE));
so the checksum is ~crc32c, right? please doc in ppl_header_entry definition
> +
> + while ((bio = bio_list_pop(&bios))) {
> + pr_debug("%s: seq: %llu submit_bio() size: %u sector: %llu dev: %s\n",
> + __func__, io->seq, bio->bi_iter.bi_size,
> + (unsigned long long)bio->bi_iter.bi_sector,
> + bdevname(bio->bi_bdev, b));
> + submit_bio(bio);
> + }
> +}
> +
> +static void ppl_submit_current_io(struct ppl_log *log)
> +{
> + struct ppl_io_unit *io;
> +
> + spin_lock_irq(&log->io_list_lock);
> +
> + io = list_first_entry_or_null(&log->io_list, struct ppl_io_unit,
> + log_sibling);
> + if (io && io->submitted)
> + io = NULL;
> +
> + spin_unlock_irq(&log->io_list_lock);
> +
> + if (io) {
> + io->submitted = true;
> +
> + if (io == log->current_io)
> + log->current_io = NULL;
> +
> + ppl_submit_iounit(io);
> + }
> +}
> +
> +void ppl_write_stripe_run(struct ppl_conf *ppl_conf)
> +{
> + struct ppl_log *log;
> + int i;
> +
> + for (i = 0; i < ppl_conf->count; i++) {
> + log = &ppl_conf->child_logs[i];
> +
> + mutex_lock(&log->io_mutex);
> + ppl_submit_current_io(log);
> + mutex_unlock(&log->io_mutex);
> + }
> +}
> +
> +static void ppl_io_unit_finished(struct ppl_io_unit *io)
> +{
> + struct ppl_log *log = io->log;
> + unsigned long flags;
> +
> + pr_debug("%s: seq: %llu\n", __func__, io->seq);
> +
> + spin_lock_irqsave(&log->io_list_lock, flags);
> +
> + list_del(&io->log_sibling);
> + mempool_free(io, log->ppl_conf->io_pool);
> +
> + if (!list_empty(&log->no_mem_stripes)) {
> + struct stripe_head *sh = list_first_entry(&log->no_mem_stripes,
> + struct stripe_head,
> + log_list);
> + list_del_init(&sh->log_list);
> + set_bit(STRIPE_HANDLE, &sh->state);
> + raid5_release_stripe(sh);
> + }
> +
> + spin_unlock_irqrestore(&log->io_list_lock, flags);
> +}
> +
> +void ppl_stripe_write_finished(struct stripe_head *sh)
> +{
> + struct ppl_io_unit *io;
> +
> + io = sh->ppl_log_io;
> + sh->ppl_log_io = NULL;
> +
> + if (io && atomic_dec_and_test(&io->pending_stripes))
> + ppl_io_unit_finished(io);
> +}
> +
> +void ppl_exit_log(struct ppl_conf *ppl_conf)
> +{
> + kfree(ppl_conf->child_logs);
> +
> + mempool_destroy(ppl_conf->meta_pool);
> + if (ppl_conf->bs)
> + bioset_free(ppl_conf->bs);
> + mempool_destroy(ppl_conf->io_pool);
> + kmem_cache_destroy(ppl_conf->io_kc);
> +
> + kfree(ppl_conf);
> +}
> +
> +static int ppl_validate_rdev(struct md_rdev *rdev)
> +{
> + char b[BDEVNAME_SIZE];
> + int ppl_data_sectors;
> + int ppl_size_new;
> +
> + /*
> + * The configured PPL size must be enough to store
> + * the header and (at the very least) partial parity
> + * for one stripe. Round it down to ensure the data
> + * space is cleanly divisible by stripe size.
> + */
> + ppl_data_sectors = rdev->ppl.size - (PPL_HEADER_SIZE >> 9);
> +
> + if (ppl_data_sectors > 0)
> + ppl_data_sectors = rounddown(ppl_data_sectors, STRIPE_SECTORS);
> +
> + if (ppl_data_sectors <= 0) {
> + pr_warn("md/raid:%s: PPL space too small on %s\n",
> + mdname(rdev->mddev), bdevname(rdev->bdev, b));
> + return -ENOSPC;
> + }
> +
> + ppl_size_new = ppl_data_sectors + (PPL_HEADER_SIZE >> 9);
> +
> + if ((rdev->ppl.sector < rdev->data_offset &&
> + rdev->ppl.sector + ppl_size_new > rdev->data_offset) ||
> + (rdev->ppl.sector >= rdev->data_offset &&
> + rdev->data_offset + rdev->sectors > rdev->ppl.sector)) {
> + pr_warn("md/raid:%s: PPL space overlaps with data on %s\n",
> + mdname(rdev->mddev), bdevname(rdev->bdev, b));
> + return -EINVAL;
> + }
> +
> + if (!rdev->mddev->external &&
> + ((rdev->ppl.offset > 0 && rdev->ppl.offset < (rdev->sb_size >> 9)) ||
> + (rdev->ppl.offset <= 0 && rdev->ppl.offset + ppl_size_new > 0))) {
> + pr_warn("md/raid:%s: PPL space overlaps with superblock on %s\n",
> + mdname(rdev->mddev), bdevname(rdev->bdev, b));
> + return -EINVAL;
> + }
> +
> + rdev->ppl.size = ppl_size_new;
> +
> + return 0;
> +}
> +
> +int ppl_init_log(struct r5conf *conf)
> +{
> + struct ppl_conf *ppl_conf;
> + struct mddev *mddev = conf->mddev;
> + int ret = 0;
> + int i;
> + bool need_cache_flush;
> +
> + if (PAGE_SIZE != 4096)
> + return -EINVAL;
> +
> + if (mddev->bitmap_info.file || mddev->bitmap_info.offset) {
> + pr_warn("md/raid:%s PPL is not compatible with bitmap\n",
> + mdname(mddev));
> + return -EINVAL;
> + }
> +
> + if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
> + pr_warn("md/raid:%s PPL is not compatible with journal\n",
> + mdname(mddev));
> + return -EINVAL;
> + }
shouldn't these two checks be put into md.c, which we load the rdev?
> +
> + ppl_conf = kzalloc(sizeof(struct ppl_conf), GFP_KERNEL);
> + if (!ppl_conf)
> + return -ENOMEM;
> +
> + ppl_conf->io_kc = KMEM_CACHE(ppl_io_unit, 0);
> + if (!ppl_conf->io_kc) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + ppl_conf->io_pool = mempool_create_slab_pool(conf->raid_disks, ppl_conf->io_kc);
> + if (!ppl_conf->io_pool) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + ppl_conf->bs = bioset_create(conf->raid_disks, 0);
> + if (!ppl_conf->bs) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + ppl_conf->meta_pool = mempool_create_page_pool(conf->raid_disks, 0);
> + if (!ppl_conf->meta_pool) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + ppl_conf->mddev = mddev;
> + ppl_conf->count = conf->raid_disks;
> + ppl_conf->child_logs = kcalloc(ppl_conf->count, sizeof(struct ppl_log),
> + GFP_KERNEL);
> + if (!ppl_conf->child_logs) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + atomic64_set(&ppl_conf->seq, 0);
> +
> + if (!mddev->external) {
> + ppl_conf->signature = ~crc32c_le(~0, mddev->uuid, sizeof(mddev->uuid));
> + ppl_conf->block_size = 512;
> + } else {
> + ppl_conf->block_size = queue_logical_block_size(mddev->queue);
> + }
Can we always set block_size 512? Don't really understand this part.
> +
> + for (i = 0; i < ppl_conf->count; i++) {
> + struct ppl_log *log = &ppl_conf->child_logs[i];
> + struct md_rdev *rdev = conf->disks[i].rdev;
> +
> + mutex_init(&log->io_mutex);
> + spin_lock_init(&log->io_list_lock);
> + INIT_LIST_HEAD(&log->io_list);
> + INIT_LIST_HEAD(&log->no_mem_stripes);
> +
> + log->ppl_conf = ppl_conf;
> + log->rdev = rdev;
> +
> + if (rdev) {
> + struct request_queue *q;
> +
> + ret = ppl_validate_rdev(rdev);
> + if (ret)
> + goto err;
> +
> + q = bdev_get_queue(rdev->bdev);
> + if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
> + need_cache_flush = true;
> + }
> + }
> +
> + if (need_cache_flush)
> + pr_warn("md/raid:%s: Volatile write-back cache should be disabled on all member drives when using PPL!\n",
> + mdname(mddev));
> +
> + conf->ppl = ppl_conf;
> +
> + return 0;
> +err:
> + ppl_exit_log(ppl_conf);
> + return ret;
> +}
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 02e02fe5b04e..21440b594878 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -739,7 +739,7 @@ static bool stripe_can_batch(struct stripe_head *sh)
> {
> struct r5conf *conf = sh->raid_conf;
>
> - if (conf->log)
> + if (conf->log || conf->ppl)
> return false;
Maybe add a new inline function into raid5-log.h
> return test_bit(STRIPE_BATCH_READY, &sh->state) &&
> !test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
> @@ -936,6 +936,9 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
> }
> }
>
> + if (conf->ppl && ppl_write_stripe(conf->ppl, sh) == 0)
> + return;
please put the one and the above raid5-cache part into a separate function into raid5-log.h
> +
> for (i = disks; i--; ) {
> int op, op_flags = 0;
> int replace_only = 0;
> @@ -3308,6 +3311,16 @@ static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
> &dd_idx, sh);
> }
>
> +static void log_stripe_write_finished(struct stripe_head *sh)
> +{
> + struct r5conf *conf = sh->raid_conf;
> +
> + if (conf->log)
> + r5l_stripe_write_finished(sh);
> + else if (conf->ppl)
> + ppl_stripe_write_finished(sh);
> +}
please put this into raid5-log.h
> +
> static void
> handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
> struct stripe_head_state *s, int disks,
> @@ -3347,7 +3360,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
> if (bi)
> bitmap_end = 1;
>
> - r5l_stripe_write_finished(sh);
> + log_stripe_write_finished(sh);
>
> if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
> wake_up(&conf->wait_for_overlap);
> @@ -3766,7 +3779,7 @@ static void handle_stripe_clean_event(struct r5conf *conf,
> discard_pending = 1;
> }
>
> - r5l_stripe_write_finished(sh);
> + log_stripe_write_finished(sh);
>
> if (!discard_pending &&
> test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
> @@ -4756,7 +4769,7 @@ static void handle_stripe(struct stripe_head *sh)
>
> if (s.just_cached)
> r5c_handle_cached_data_endio(conf, sh, disks, &s.return_bi);
> - r5l_stripe_write_finished(sh);
> + log_stripe_write_finished(sh);
>
> /* Now we might consider reading some blocks, either to check/generate
> * parity, or to satisfy requests
> @@ -6120,6 +6133,14 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
> return handled;
> }
>
> +static void log_write_stripe_run(struct r5conf *conf)
> +{
> + if (conf->log)
> + r5l_write_stripe_run(conf->log);
> + else if (conf->ppl)
> + ppl_write_stripe_run(conf->ppl);
> +}
ditto
> +
> static int handle_active_stripes(struct r5conf *conf, int group,
> struct r5worker *worker,
> struct list_head *temp_inactive_list)
> @@ -6157,7 +6178,7 @@ static int handle_active_stripes(struct r5conf *conf, int group,
>
> for (i = 0; i < batch_size; i++)
> handle_stripe(batch[i]);
> - r5l_write_stripe_run(conf->log);
> + log_write_stripe_run(conf);
>
> cond_resched();
>
> @@ -6735,6 +6756,8 @@ static void free_conf(struct r5conf *conf)
>
> if (conf->log)
> r5l_exit_log(conf->log);
> + if (conf->ppl)
> + ppl_exit_log(conf->ppl);
Ditto
> if (conf->shrinker.nr_deferred)
> unregister_shrinker(&conf->shrinker);
>
> @@ -7196,6 +7219,13 @@ static int raid5_run(struct mddev *mddev)
> BUG_ON(mddev->delta_disks != 0);
> }
>
> + if (test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
> + test_bit(MD_HAS_PPL, &mddev->flags)) {
> + pr_warn("md/raid:%s: using journal device and PPL not allowed - disabling PPL\n",
> + mdname(mddev));
> + clear_bit(MD_HAS_PPL, &mddev->flags);
> + }
> +
> if (mddev->private == NULL)
> conf = setup_conf(mddev);
> else
> @@ -7422,6 +7452,11 @@ static int raid5_run(struct mddev *mddev)
> mdname(mddev), bdevname(journal_dev->bdev, b));
> if (r5l_init_log(conf, journal_dev))
> goto abort;
> + } else if (test_bit(MD_HAS_PPL, &mddev->flags)) {
> + pr_debug("md/raid:%s: enabling distributed Partial Parity Log\n",
> + mdname(mddev));
> + if (ppl_init_log(conf))
> + goto abort;
> }
Ditto, if possible
>
> return 0;
> @@ -7690,7 +7725,7 @@ static int raid5_resize(struct mddev *mddev, sector_t sectors)
> sector_t newsize;
> struct r5conf *conf = mddev->private;
>
> - if (conf->log)
> + if (conf->log || conf->ppl)
> return -EINVAL;
> sectors &= ~((sector_t)conf->chunk_sectors - 1);
> newsize = raid5_size(mddev, sectors, mddev->raid_disks);
> @@ -7743,7 +7778,7 @@ static int check_reshape(struct mddev *mddev)
> {
> struct r5conf *conf = mddev->private;
>
> - if (conf->log)
> + if (conf->log || conf->ppl)
there are other places we check conf->log. like stripe_can_batch(), I think the
ppl code can't hanel batch right now.
> return -EINVAL;
> if (mddev->delta_disks == 0 &&
> mddev->new_layout == mddev->layout &&
> diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
> index 3cc4cb28f7e6..f915a7a0e752 100644
> --- a/drivers/md/raid5.h
> +++ b/drivers/md/raid5.h
> @@ -230,6 +230,7 @@ struct stripe_head {
> struct list_head r5c; /* for r5c_cache->stripe_in_journal */
>
> struct page *ppl_page; /* partial parity of this stripe */
> + struct ppl_io_unit *ppl_log_io;
Maybe we should put the ppl fields and raid5 fields to a union
> /**
> * struct stripe_operations
> * @target - STRIPE_OP_COMPUTE_BLK target
> @@ -689,6 +690,7 @@ struct r5conf {
> int group_cnt;
> int worker_cnt_per_group;
> struct r5l_log *log;
> + struct ppl_conf *ppl;
Maybe use void * log_private, so works for both raid5-cache and ppl
>
> struct bio_list pending_bios;
> spinlock_t pending_bios_lock;
> @@ -798,4 +800,10 @@ extern void r5c_check_cached_full_stripe(struct r5conf *conf);
> extern struct md_sysfs_entry r5c_journal_mode;
> extern void r5c_update_on_rdev_error(struct mddev *mddev);
> extern bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect);
> +
> +extern int ppl_init_log(struct r5conf *conf);
> +extern void ppl_exit_log(struct ppl_conf *log);
> +extern int ppl_write_stripe(struct ppl_conf *log, struct stripe_head *sh);
> +extern void ppl_write_stripe_run(struct ppl_conf *log);
> +extern void ppl_stripe_write_finished(struct stripe_head *sh);
These part and the raid5 part should be put into raid5-log.h
> #endif
> diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
> index fe2112810c43..2c28711cc5f1 100644
> --- a/include/uapi/linux/raid/md_p.h
> +++ b/include/uapi/linux/raid/md_p.h
> @@ -398,4 +398,30 @@ struct r5l_meta_block {
>
> #define R5LOG_VERSION 0x1
> #define R5LOG_MAGIC 0x6433c509
> +
> +struct ppl_header_entry {
> + __le64 data_sector; /* Raid sector of the new data */
> + __le32 pp_size; /* Length of partial parity */
> + __le32 data_size; /* Length of data */
> + __le32 parity_disk; /* Member disk containing parity */
> + __le32 checksum; /* Checksum of this entry */
So we changed the disk format. Will this new format be put into IMSM standard?
Do we have a version to verify the old/new format for IMSM?
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 4/7] md: add sysfs entries for PPL
2017-02-21 19:43 ` [PATCH v4 4/7] md: add sysfs entries for PPL Artur Paszkiewicz
@ 2017-02-28 0:37 ` Shaohua Li
2017-03-01 16:13 ` Artur Paszkiewicz
0 siblings, 1 reply; 25+ messages in thread
From: Shaohua Li @ 2017-02-28 0:37 UTC (permalink / raw)
To: Artur Paszkiewicz; +Cc: shli, linux-raid
On Tue, Feb 21, 2017 at 08:43:58PM +0100, Artur Paszkiewicz wrote:
> Add 'consistency_policy' attribute for array. It indicates how the array
> maintains consistency in case of unexpected shutdown.
>
> Add 'ppl_sector' and 'ppl_size' for rdev, which describe the location
> and size of the PPL space on the device. They can't be changed for
> active members if the array is started and PPL is enabled, so in the
> setter functions only basic checks are performed. More checks are done
> in ppl_validate_rdev() when starting the log.
>
> These attributes are writable to allow enabling PPL for external
> metadata arrays and (later) to enable/disable PPL for a running array.
>
> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
> ---
> Documentation/admin-guide/md.rst | 32 ++++++++++-
> drivers/md/md.c | 115 +++++++++++++++++++++++++++++++++++++++
> 2 files changed, 144 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst
> index 1e61bf50595c..84de718f24a4 100644
> --- a/Documentation/admin-guide/md.rst
> +++ b/Documentation/admin-guide/md.rst
> @@ -276,14 +276,14 @@ All md devices contain:
> array creation it will default to 0, though starting the array as
> ``clean`` will set it much larger.
>
> - new_dev
> + new_dev
> This file can be written but not read. The value written should
> be a block device number as major:minor. e.g. 8:0
> This will cause that device to be attached to the array, if it is
> available. It will then appear at md/dev-XXX (depending on the
> name of the device) and further configuration is then possible.
>
> - safe_mode_delay
> + safe_mode_delay
> When an md array has seen no write requests for a certain period
> of time, it will be marked as ``clean``. When another write
> request arrives, the array is marked as ``dirty`` before the write
> @@ -292,7 +292,7 @@ All md devices contain:
> period as a number of seconds. The default is 200msec (0.200).
> Writing a value of 0 disables safemode.
>
> - array_state
> + array_state
> This file contains a single word which describes the current
> state of the array. In many cases, the state can be set by
> writing the word for the desired state, however some states
> @@ -401,7 +401,30 @@ All md devices contain:
> once the array becomes non-degraded, and this fact has been
> recorded in the metadata.
>
> + consistency_policy
> + This indicates how the array maintains consistency in case of unexpected
> + shutdown. It can be:
>
> + none
> + Array has no redundancy information, e.g. raid0, linear.
> +
> + resync
> + Full resync is performed and all redundancy is regenerated when the
> + array is started after unclean shutdown.
> +
> + bitmap
> + Resync assisted by a write-intent bitmap.
> +
> + journal
> + For raid4/5/6, journal device is used to log transactions and replay
> + after unclean shutdown.
> +
> + ppl
> + For raid5 only, Partial Parity Log is used to close the write hole and
> + eliminate resync.
> +
> + The accepted values when writing to this file are ``ppl`` and ``resync``,
> + used to enable and disable PPL.
>
>
> As component devices are added to an md array, they appear in the ``md``
> @@ -563,6 +586,9 @@ Each directory contains:
> adds bad blocks without acknowledging them. This is largely
> for testing.
>
> + ppl_sector, ppl_size
> + Location and size (in sectors) of the space used for Partial Parity Log
> + on this device.
>
>
> An active md device will also contain an entry for each active device
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index c2028007b209..3ff979d538d4 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -3157,6 +3157,78 @@ static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)
> static struct rdev_sysfs_entry rdev_unack_bad_blocks =
> __ATTR(unacknowledged_bad_blocks, S_IRUGO|S_IWUSR, ubb_show, ubb_store);
>
> +static ssize_t
> +ppl_sector_show(struct md_rdev *rdev, char *page)
> +{
> + return sprintf(page, "%llu\n", (unsigned long long)rdev->ppl.sector);
> +}
> +
> +static ssize_t
> +ppl_sector_store(struct md_rdev *rdev, const char *buf, size_t len)
> +{
> + unsigned long long sector;
> +
> + if (kstrtoull(buf, 10, §or) < 0)
> + return -EINVAL;
Maybe use base 0 to be more friendly
> + if (sector != (sector_t)sector)
> + return -EINVAL;
> +
> + if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
> + rdev->raid_disk >= 0)
> + return -EBUSY;
> +
> + if (rdev->mddev->persistent) {
> + if (rdev->mddev->major_version == 0)
> + return -EINVAL;
> + if ((sector > rdev->sb_start &&
> + sector - rdev->sb_start > S16_MAX) ||
> + (sector < rdev->sb_start &&
> + rdev->sb_start - sector > -S16_MIN))
> + return -EINVAL;
Don't check if the address overlaps with data?
> + rdev->ppl.offset = sector - rdev->sb_start;
> + } else if (!rdev->mddev->external) {
> + return -EBUSY;
> + }
generally we don't use {} for single line code
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 5/7] raid5-ppl: load and recover the log
2017-02-21 19:43 ` [PATCH v4 5/7] raid5-ppl: load and recover the log Artur Paszkiewicz
@ 2017-02-28 1:12 ` Shaohua Li
2017-03-01 16:14 ` Artur Paszkiewicz
0 siblings, 1 reply; 25+ messages in thread
From: Shaohua Li @ 2017-02-28 1:12 UTC (permalink / raw)
To: Artur Paszkiewicz; +Cc: shli, linux-raid
On Tue, Feb 21, 2017 at 08:43:59PM +0100, Artur Paszkiewicz wrote:
> Load the log from each disk when starting the array and recover if the
> array is dirty.
>
> The initial empty PPL is written by mdadm. When loading the log we
> verify the header checksum and signature. For external metadata arrays
> the signature is verified in userspace, so here we read it from the
> header, verifying only if it matches on all disks, and use it later when
> writing PPL.
>
> In addition to the header checksum, each header entry also contains a
> checksum of its partial parity data. If the header is valid, recovery is
> performed for each entry until an invalid entry is found. If the array
> is not degraded and recovery using PPL fully succeeds, there is no need
> to resync the array because data and parity will be consistent, so in
> this case resync will be disabled.
>
> Due to compatibility with IMSM implementations on other systems, we
> can't assume that the recovery data block size is always 4K. Writes
> generated by MD raid5 don't have this issue, but when recovering PPL
> written in other environments it is possible to have entries with
> 512-byte sector granularity. The recovery code takes this into account
> and also the logical sector size of the underlying drives.
>
> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
> ---
> drivers/md/raid5-ppl.c | 483 +++++++++++++++++++++++++++++++++++++++++++++++++
> drivers/md/raid5.c | 5 +-
> 2 files changed, 487 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
> index a00cabf1adf6..a7693353243a 100644
> --- a/drivers/md/raid5-ppl.c
> +++ b/drivers/md/raid5-ppl.c
> @@ -16,6 +16,7 @@
> #include <linux/blkdev.h>
> #include <linux/slab.h>
> #include <linux/crc32c.h>
> +#include <linux/async_tx.h>
> #include <linux/raid/md_p.h>
> #include "md.h"
> #include "raid5.h"
> @@ -84,6 +85,10 @@ struct ppl_conf {
> mempool_t *io_pool;
> struct bio_set *bs;
> mempool_t *meta_pool;
> +
> + /* used only for recovery */
> + int recovered_entries;
> + int mismatch_count;
> };
>
> struct ppl_log {
> @@ -450,6 +455,467 @@ void ppl_stripe_write_finished(struct stripe_head *sh)
> ppl_io_unit_finished(io);
> }
>
> +static void ppl_xor(int size, struct page *page1, struct page *page2,
> + struct page *page_result)
> +{
> + struct async_submit_ctl submit;
> + struct dma_async_tx_descriptor *tx;
> + struct page *xor_srcs[] = { page1, page2 };
> +
> + init_async_submit(&submit, ASYNC_TX_ACK|ASYNC_TX_XOR_DROP_DST,
> + NULL, NULL, NULL, NULL);
> + tx = async_xor(page_result, xor_srcs, 0, 2, size, &submit);
> +
> + async_tx_quiesce(&tx);
> +}
> +
> +/*
> + * PPL recovery strategy: xor partial parity and data from all modified data
> + * disks within a stripe and write the result as the new stripe parity. If all
> + * stripe data disks are modified (full stripe write), no partial parity is
> + * available, so just xor the data disks.
> + *
> + * Recovery of a PPL entry shall occur only if all modified data disks are
> + * available and read from all of them succeeds.
> + *
> + * A PPL entry applies to a stripe, partial parity size for an entry is at most
> + * the size of the chunk. Examples of possible cases for a single entry:
> + *
> + * case 0: single data disk write:
> + * data0 data1 data2 ppl parity
> + * +--------+--------+--------+ +--------------------+
> + * | ------ | ------ | ------ | +----+ | (no change) |
> + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
> + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
> + * | ------ | ------ | ------ | +----+ | (no change) |
> + * +--------+--------+--------+ +--------------------+
> + * pp_size = data_size
> + *
> + * case 1: more than one data disk write:
> + * data0 data1 data2 ppl parity
> + * +--------+--------+--------+ +--------------------+
> + * | ------ | ------ | ------ | +----+ | (no change) |
> + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
> + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
> + * | ------ | ------ | ------ | +----+ | (no change) |
> + * +--------+--------+--------+ +--------------------+
> + * pp_size = data_size / modified_data_disks
> + *
> + * case 2: write to all data disks (also full stripe write):
> + * data0 data1 data2 parity
> + * +--------+--------+--------+ +--------------------+
> + * | ------ | ------ | ------ | | (no change) |
> + * | -data- | -data- | -data- | --------> | xor all data |
> + * | ------ | ------ | ------ | --------> | (no change) |
> + * | ------ | ------ | ------ | | (no change) |
> + * +--------+--------+--------+ +--------------------+
> + * pp_size = 0
> + *
> + * The following cases are possible only in other implementations. The recovery
> + * code can handle them, but they are not generated at runtime because they can
> + * be reduced to cases 0, 1 and 2:
> + *
> + * case 3:
> + * data0 data1 data2 ppl parity
> + * +--------+--------+--------+ +----+ +--------------------+
> + * | ------ | -data- | -data- | | pp | | data1 ^ data2 ^ pp |
> + * | ------ | -data- | -data- | | pp | -> | data1 ^ data2 ^ pp |
> + * | -data- | -data- | -data- | | -- | -> | xor all data |
> + * | -data- | -data- | ------ | | pp | | data0 ^ data1 ^ pp |
> + * +--------+--------+--------+ +----+ +--------------------+
> + * pp_size = chunk_size
> + *
> + * case 4:
> + * data0 data1 data2 ppl parity
> + * +--------+--------+--------+ +----+ +--------------------+
> + * | ------ | -data- | ------ | | pp | | data1 ^ pp |
> + * | ------ | ------ | ------ | | -- | -> | (no change) |
> + * | ------ | ------ | ------ | | -- | -> | (no change) |
> + * | -data- | ------ | ------ | | pp | | data0 ^ pp |
> + * +--------+--------+--------+ +----+ +--------------------+
> + * pp_size = chunk_size
> + */
> +static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
> + sector_t ppl_sector)
> +{
> + struct ppl_conf *ppl_conf = log->ppl_conf;
> + struct mddev *mddev = ppl_conf->mddev;
> + struct r5conf *conf = mddev->private;
> + int block_size = ppl_conf->block_size;
> + struct page *pages;
> + struct page *page1;
> + struct page *page2;
> + sector_t r_sector_first;
> + sector_t r_sector_last;
> + int strip_sectors;
> + int data_disks;
> + int i;
> + int ret = 0;
> + char b[BDEVNAME_SIZE];
> + unsigned int pp_size = le32_to_cpu(e->pp_size);
> + unsigned int data_size = le32_to_cpu(e->data_size);
> +
> + r_sector_first = le64_to_cpu(e->data_sector) * (block_size >> 9);
> +
> + if ((pp_size >> 9) < conf->chunk_sectors) {
> + if (pp_size > 0) {
> + data_disks = data_size / pp_size;
> + strip_sectors = pp_size >> 9;
> + } else {
> + data_disks = conf->raid_disks - conf->max_degraded;
> + strip_sectors = (data_size >> 9) / data_disks;
> + }
> + r_sector_last = r_sector_first +
> + (data_disks - 1) * conf->chunk_sectors +
> + strip_sectors;
> + } else {
> + data_disks = conf->raid_disks - conf->max_degraded;
> + strip_sectors = conf->chunk_sectors;
> + r_sector_last = r_sector_first + (data_size >> 9);
> + }
> +
> + pages = alloc_pages(GFP_KERNEL, 1);
order != 0 allocation should be avoid if possible. Here sounds not necessary
> + if (!pages)
> + return -ENOMEM;
> + page1 = pages;
> + page2 = pages + 1;
> +
> + pr_debug("%s: array sector first: %llu last: %llu\n", __func__,
> + (unsigned long long)r_sector_first,
> + (unsigned long long)r_sector_last);
> +
> + /* if start and end is 4k aligned, use a 4k block */
> + if (block_size == 512 &&
> + (r_sector_first & (STRIPE_SECTORS - 1)) == 0 &&
> + (r_sector_last & (STRIPE_SECTORS - 1)) == 0)
> + block_size = STRIPE_SIZE;
> +
> + /* iterate through blocks in strip */
> + for (i = 0; i < strip_sectors; i += (block_size >> 9)) {
> + bool update_parity = false;
> + sector_t parity_sector;
> + struct md_rdev *parity_rdev;
> + struct stripe_head sh;
> + int disk;
> + int indent = 0;
> +
> + pr_debug("%s:%*s iter %d start\n", __func__, indent, "", i);
> + indent += 2;
> +
> + memset(page_address(page1), 0, PAGE_SIZE);
> +
> + /* iterate through data member disks */
> + for (disk = 0; disk < data_disks; disk++) {
> + int dd_idx;
> + struct md_rdev *rdev;
> + sector_t sector;
> + sector_t r_sector = r_sector_first + i +
> + (disk * conf->chunk_sectors);
> +
> + pr_debug("%s:%*s data member disk %d start\n",
> + __func__, indent, "", disk);
> + indent += 2;
> +
> + if (r_sector >= r_sector_last) {
> + pr_debug("%s:%*s array sector %llu doesn't need parity update\n",
> + __func__, indent, "",
> + (unsigned long long)r_sector);
> + indent -= 2;
> + continue;
> + }
> +
> + update_parity = true;
> +
> + /* map raid sector to member disk */
> + sector = raid5_compute_sector(conf, r_sector, 0,
> + &dd_idx, NULL);
> + pr_debug("%s:%*s processing array sector %llu => data member disk %d, sector %llu\n",
> + __func__, indent, "",
> + (unsigned long long)r_sector, dd_idx,
> + (unsigned long long)sector);
> +
> + rdev = conf->disks[dd_idx].rdev;
> + if (!rdev) {
> + pr_debug("%s:%*s data member disk %d missing\n",
> + __func__, indent, "", dd_idx);
> + update_parity = false;
> + break;
> + }
> +
> + pr_debug("%s:%*s reading data member disk %s sector %llu\n",
> + __func__, indent, "", bdevname(rdev->bdev, b),
> + (unsigned long long)sector);
> + if (!sync_page_io(rdev, sector, block_size, page2,
> + REQ_OP_READ, 0, false)) {
> + md_error(mddev, rdev);
> + pr_debug("%s:%*s read failed!\n", __func__,
> + indent, "");
> + ret = -EIO;
> + goto out;
> + }
> +
> + ppl_xor(block_size, page1, page2, page1);
> +
> + indent -= 2;
> + }
> +
> + if (!update_parity)
> + continue;
> +
> + if (pp_size > 0) {
> + pr_debug("%s:%*s reading pp disk sector %llu\n",
> + __func__, indent, "",
> + (unsigned long long)(ppl_sector + i));
> + if (!sync_page_io(log->rdev,
> + ppl_sector - log->rdev->data_offset + i,
> + block_size, page2, REQ_OP_READ, 0,
> + false)) {
> + pr_debug("%s:%*s read failed!\n", __func__,
> + indent, "");
> + md_error(mddev, log->rdev);
> + ret = -EIO;
> + goto out;
> + }
> +
> + ppl_xor(block_size, page1, page2, page1);
> + }
> +
> + /* map raid sector to parity disk */
> + parity_sector = raid5_compute_sector(conf, r_sector_first + i,
> + 0, &disk, &sh);
> + BUG_ON(sh.pd_idx != le32_to_cpu(e->parity_disk));
> + parity_rdev = conf->disks[sh.pd_idx].rdev;
> +
> + BUG_ON(parity_rdev->bdev->bd_dev != log->rdev->bdev->bd_dev);
> + pr_debug("%s:%*s write parity at sector %llu, disk %s\n",
> + __func__, indent, "",
> + (unsigned long long)parity_sector,
> + bdevname(parity_rdev->bdev, b));
> + if (!sync_page_io(parity_rdev, parity_sector, block_size,
> + page1, REQ_OP_WRITE, 0, false)) {
> + pr_debug("%s:%*s parity write error!\n", __func__,
> + indent, "");
> + md_error(mddev, parity_rdev);
> + ret = -EIO;
> + goto out;
> + }
> + }
> +out:
> + __free_pages(pages, 1);
> + return ret;
> +}
> +
> +static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr)
> +{
> + struct ppl_conf *ppl_conf = log->ppl_conf;
> + struct md_rdev *rdev = log->rdev;
> + struct mddev *mddev = rdev->mddev;
> + sector_t ppl_sector = rdev->ppl.sector + (PPL_HEADER_SIZE >> 9);
> + struct page *page;
> + int i;
> + int ret = 0;
> +
> + page = alloc_page(GFP_KERNEL);
> + if (!page)
> + return -ENOMEM;
> +
> + /* iterate through all PPL entries saved */
> + for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++) {
> + struct ppl_header_entry *e = &pplhdr->entries[i];
> + u32 pp_size = le32_to_cpu(e->pp_size);
> + sector_t sector = ppl_sector;
> + int ppl_entry_sectors = pp_size >> 9;
> + u32 crc, crc_stored;
> +
> + pr_debug("%s: disk: %d entry: %d ppl_sector: %llu pp_size: %u\n",
> + __func__, rdev->raid_disk, i,
> + (unsigned long long)ppl_sector, pp_size);
> +
> + crc = ~0;
> + crc_stored = le32_to_cpu(e->checksum);
> +
> + /* read parial parity for this entry and calculate its checksum */
> + while (pp_size) {
> + int s = pp_size > PAGE_SIZE ? PAGE_SIZE : pp_size;
> +
> + if (!sync_page_io(rdev, sector - rdev->data_offset,
> + s, page, REQ_OP_READ, 0, false)) {
> + md_error(mddev, rdev);
> + ret = -EIO;
> + goto out;
> + }
> +
> + crc = crc32c_le(crc, page_address(page), s);
> +
> + pp_size -= s;
> + sector += s >> 9;
> + }
> +
> + crc = ~crc;
> +
> + if (crc != crc_stored) {
> + /*
> + * Don't recover this entry if the checksum does not
> + * match, but keep going and try to recover other
> + * entries.
> + */
> + pr_debug("%s: ppl entry crc does not match: stored: 0x%x calculated: 0x%x\n",
> + __func__, crc_stored, crc);
> + ppl_conf->mismatch_count++;
> + } else {
> + ret = ppl_recover_entry(log, e, ppl_sector);
> + if (ret)
> + goto out;
> + ppl_conf->recovered_entries++;
> + }
> +
> + ppl_sector += ppl_entry_sectors;
> + }
> +out:
> + __free_page(page);
> + return ret;
> +}
> +
> +static int ppl_write_empty_header(struct ppl_log *log)
> +{
> + struct page *page;
> + struct ppl_header *pplhdr;
> + struct md_rdev *rdev = log->rdev;
> + int ret = 0;
> +
> + pr_debug("%s: disk: %d ppl_sector: %llu\n", __func__,
> + rdev->raid_disk, (unsigned long long)rdev->ppl.sector);
> +
> + page = alloc_page(GFP_NOIO | __GFP_ZERO);
> + if (!page)
> + return -ENOMEM;
> +
> + pplhdr = page_address(page);
> + memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
> + pplhdr->signature = cpu_to_le32(log->ppl_conf->signature);
> + pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));
> +
> + if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
> + PPL_HEADER_SIZE, page, REQ_OP_WRITE, 0, false)) {
write with FUA? otherwise, the empty header might not set down in the disks.
> + md_error(rdev->mddev, rdev);
> + ret = -EIO;
> + }
> +
> + __free_page(page);
> + return ret;
> +}
> +
> +static int ppl_load_distributed(struct ppl_log *log)
> +{
> + struct ppl_conf *ppl_conf = log->ppl_conf;
> + struct md_rdev *rdev = log->rdev;
> + struct mddev *mddev = rdev->mddev;
> + struct page *page;
> + struct ppl_header *pplhdr;
> + u32 crc, crc_stored;
> + u32 signature;
> + int ret = 0;
> +
> + pr_debug("%s: disk: %d\n", __func__, rdev->raid_disk);
> +
> + /* read PPL header */
> + page = alloc_page(GFP_KERNEL);
> + if (!page)
> + return -ENOMEM;
> +
> + if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
> + PAGE_SIZE, page, REQ_OP_READ, 0, false)) {
> + md_error(mddev, rdev);
> + ret = -EIO;
> + goto out;
> + }
> + pplhdr = page_address(page);
> +
> + /* check header validity */
> + crc_stored = le32_to_cpu(pplhdr->checksum);
> + pplhdr->checksum = 0;
> + crc = ~crc32c_le(~0, pplhdr, PAGE_SIZE);
> +
> + if (crc_stored != crc) {
> + pr_debug("%s: ppl header crc does not match: stored: 0x%x calculated: 0x%x\n",
> + __func__, crc_stored, crc);
> + ppl_conf->mismatch_count++;
> + goto out;
> + }
> +
> + signature = le32_to_cpu(pplhdr->signature);
> +
> + if (mddev->external) {
> + /*
> + * For external metadata the header signature is set and
> + * validated in userspace.
> + */
> + ppl_conf->signature = signature;
> + } else if (ppl_conf->signature != signature) {
> + pr_debug("%s: ppl header signature does not match: stored: 0x%x configured: 0x%x\n",
> + __func__, signature, ppl_conf->signature);
> + ppl_conf->mismatch_count++;
> + goto out;
> + }
> +
> + /* attempt to recover from log if we are starting a dirty array */
> + if (!mddev->pers && mddev->recovery_cp != MaxSector)
> + ret = ppl_recover(log, pplhdr);
when could mddev->pers be null?
we need flush disk cache here. I know you assume disks don't enable cache yet,
but it's simple to do a flush here.
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 6/7] raid5-ppl: support disk hot add/remove with PPL
2017-02-21 19:44 ` [PATCH v4 6/7] raid5-ppl: support disk hot add/remove with PPL Artur Paszkiewicz
@ 2017-02-28 1:22 ` Shaohua Li
2017-03-01 16:14 ` Artur Paszkiewicz
0 siblings, 1 reply; 25+ messages in thread
From: Shaohua Li @ 2017-02-28 1:22 UTC (permalink / raw)
To: Artur Paszkiewicz; +Cc: shli, linux-raid
On Tue, Feb 21, 2017 at 08:44:00PM +0100, Artur Paszkiewicz wrote:
> Add a function to modify the log by removing an rdev when a drive fails
> or adding when a spare/replacement is activated as a raid member.
>
> Removing a disk just clears the child log rdev pointer. No new stripes
> will be accepted for this child log in ppl_write_stripe() and running io
> units will be processed without writing PPL to the device.
>
> Adding a disk sets the child log rdev pointer and writes an empty PPL
> header.
>
> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
> ---
> drivers/md/raid5-ppl.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
> drivers/md/raid5.c | 15 +++++++++++++++
> drivers/md/raid5.h | 8 ++++++++
> 3 files changed, 70 insertions(+)
>
> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
> index a7693353243a..c2070d124849 100644
> --- a/drivers/md/raid5-ppl.c
> +++ b/drivers/md/raid5-ppl.c
> @@ -319,6 +319,12 @@ static void ppl_submit_iounit(struct ppl_io_unit *io)
>
> bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, ppl_conf->bs);
> bio->bi_private = io;
> +
> + if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
> + ppl_log_endio(bio);
> + return;
> + }
> +
> bio->bi_end_io = ppl_log_endio;
> bio->bi_opf = REQ_OP_WRITE | REQ_FUA;
> bio->bi_bdev = log->rdev->bdev;
> @@ -1098,3 +1104,44 @@ int ppl_init_log(struct r5conf *conf)
> ppl_exit_log(ppl_conf);
> return ret;
> }
> +
> +int ppl_modify_log(struct ppl_conf *ppl_conf, struct md_rdev *rdev,
> + enum ppl_modify_log_operation operation)
> +{
> + struct ppl_log *log;
> + int ret = 0;
> + char b[BDEVNAME_SIZE];
> +
> + if (!rdev)
> + return -EINVAL;
> +
> + pr_debug("%s: disk: %d operation: %s dev: %s\n",
> + __func__, rdev->raid_disk,
> + operation == PPL_MODIFY_LOG_DISK_REMOVE ? "remove" :
> + (operation == PPL_MODIFY_LOG_DISK_ADD ? "add" : "?"),
> + bdevname(rdev->bdev, b));
> +
> + if (rdev->raid_disk < 0)
> + return 0;
> +
> + if (rdev->raid_disk >= ppl_conf->count)
> + return -ENODEV;
> +
> + log = &ppl_conf->child_logs[rdev->raid_disk];
> +
> + mutex_lock(&log->io_mutex);
> + if (operation == PPL_MODIFY_LOG_DISK_REMOVE) {
> + log->rdev = NULL;
> + } else if (operation == PPL_MODIFY_LOG_DISK_ADD) {
> + ret = ppl_validate_rdev(rdev);
> + if (!ret) {
> + log->rdev = rdev;
> + ret = ppl_write_empty_header(log);
> + }
> + } else {
> + ret = -EINVAL;
> + }
> + mutex_unlock(&log->io_mutex);
> +
> + return ret;
> +}
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 8b52392457d8..b17e90f06f19 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -7623,6 +7623,12 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
> *rdevp = rdev;
> }
> }
> + if (conf->ppl) {
> + err = ppl_modify_log(conf->ppl, rdev,
> + PPL_MODIFY_LOG_DISK_REMOVE);
> + if (err)
> + goto abort;
> + }
> if (p->replacement) {
> /* We must have just cleared 'rdev' */
> p->rdev = p->replacement;
> @@ -7632,6 +7638,10 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
> */
> p->replacement = NULL;
> clear_bit(WantReplacement, &rdev->flags);
> +
> + if (conf->ppl)
> + err = ppl_modify_log(conf->ppl, p->rdev,
> + PPL_MODIFY_LOG_DISK_ADD);
> } else
> /* We might have just removed the Replacement as faulty-
> * clear the bit just in case
> @@ -7695,6 +7705,11 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
> if (rdev->saved_raid_disk != disk)
> conf->fullsync = 1;
> rcu_assign_pointer(p->rdev, rdev);
> +
> + if (conf->ppl)
> + err = ppl_modify_log(conf->ppl, rdev,
> + PPL_MODIFY_LOG_DISK_ADD);
> +
> goto out;
> }
> }
> diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
> index f915a7a0e752..43cfa5fa71b3 100644
> --- a/drivers/md/raid5.h
> +++ b/drivers/md/raid5.h
> @@ -806,4 +806,12 @@ extern void ppl_exit_log(struct ppl_conf *log);
> extern int ppl_write_stripe(struct ppl_conf *log, struct stripe_head *sh);
> extern void ppl_write_stripe_run(struct ppl_conf *log);
> extern void ppl_stripe_write_finished(struct stripe_head *sh);
> +
> +enum ppl_modify_log_operation {
> + PPL_MODIFY_LOG_DISK_REMOVE,
> + PPL_MODIFY_LOG_DISK_ADD,
> +};
a bool for this parameter is better
> +extern int ppl_modify_log(struct ppl_conf *log, struct md_rdev *rdev,
> + enum ppl_modify_log_operation operation);
So this should be put into raid5-log.h and rename to log_modify_log(conf, xxx)
or other sensible name.
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 7/7] raid5-ppl: runtime PPL enabling or disabling
2017-02-21 19:44 ` [PATCH v4 7/7] raid5-ppl: runtime PPL enabling or disabling Artur Paszkiewicz
@ 2017-02-28 1:31 ` Shaohua Li
2017-03-01 16:14 ` Artur Paszkiewicz
0 siblings, 1 reply; 25+ messages in thread
From: Shaohua Li @ 2017-02-28 1:31 UTC (permalink / raw)
To: Artur Paszkiewicz; +Cc: shli, linux-raid
On Tue, Feb 21, 2017 at 08:44:01PM +0100, Artur Paszkiewicz wrote:
> Allow writing to 'consistency_policy' attribute when the array is
> active. Add a new function 'change_consistency_policy' to the
> md_personality operations structure to handle the change in the
> personality code. Values "ppl" and "resync" are accepted and
> turn PPL on and off respectively.
>
> When enabling PPL its location and size should first be set using
> 'ppl_sector' and 'ppl_size' attributes and a valid PPL header should be
> written at this location on each member device.
>
> Enabling or disabling PPL is performed under a suspended array. The
> raid5_reset_stripe_cache function frees the stripe cache and allocates
> it again in order to allocate or free the ppl_pages for the stripes in
> the stripe cache.
>
> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
> ---
> drivers/md/md.c | 12 ++++++++---
> drivers/md/md.h | 2 ++
> drivers/md/raid5-ppl.c | 4 ++++
> drivers/md/raid5.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 73 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 3ff979d538d4..b70e19513588 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -5003,14 +5003,20 @@ consistency_policy_show(struct mddev *mddev, char *page)
> static ssize_t
> consistency_policy_store(struct mddev *mddev, const char *buf, size_t len)
> {
> + int err = 0;
> +
> if (mddev->pers) {
> - return -EBUSY;
> + if (mddev->pers->change_consistency_policy)
> + err = mddev->pers->change_consistency_policy(mddev, buf);
> + else
> + err = -EBUSY;
> } else if (mddev->external && strncmp(buf, "ppl", 3) == 0) {
> set_bit(MD_HAS_PPL, &mddev->flags);
> - return len;
> } else {
> - return -EINVAL;
> + err = -EINVAL;
> }
> +
> + return err ? err : len;
> }
>
> static struct md_sysfs_entry md_consistency_policy =
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 66a5a16e79f7..88a5155c152e 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -548,6 +548,8 @@ struct md_personality
> /* congested implements bdi.congested_fn().
> * Will not be called while array is 'suspended' */
> int (*congested)(struct mddev *mddev, int bits);
> + /* Changes the consistency policy of an active array. */
> + int (*change_consistency_policy)(struct mddev *mddev, const char *buf);
> };
>
> struct md_sysfs_entry {
> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
> index c2070d124849..a5c4d3333bce 100644
> --- a/drivers/md/raid5-ppl.c
> +++ b/drivers/md/raid5-ppl.c
> @@ -1095,6 +1095,10 @@ int ppl_init_log(struct r5conf *conf)
> */
> mddev->recovery_cp = MaxSector;
> set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
> + } else if (mddev->pers && ppl_conf->mismatch_count > 0) {
> + /* no mismatch allowed when enabling PPL for a running array */
> + ret = -EINVAL;
> + goto err;
> }
>
> conf->ppl = ppl_conf;
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index b17e90f06f19..754fb8e1c76f 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -8319,6 +8319,63 @@ static void *raid6_takeover(struct mddev *mddev)
> return setup_conf(mddev);
> }
>
> +static void raid5_reset_stripe_cache(struct mddev *mddev)
> +{
> + struct r5conf *conf = mddev->private;
> +
> + mutex_lock(&conf->cache_size_mutex);
> + while (conf->max_nr_stripes &&
> + drop_one_stripe(conf))
> + ;
> + while (conf->min_nr_stripes > conf->max_nr_stripes &&
> + grow_one_stripe(conf, GFP_KERNEL))
> + ;
> + mutex_unlock(&conf->cache_size_mutex);
> +}
> +
> +static int raid5_change_consistency_policy(struct mddev *mddev, const char *buf)
> +{
> + struct r5conf *conf;
> + int err;
> +
> + err = mddev_lock(mddev);
> + if (err)
> + return err;
> + conf = mddev->private;
> + if (!conf) {
> + mddev_unlock(mddev);
> + return -ENODEV;
> + }
> +
> + if (strncmp(buf, "ppl", 3) == 0 &&
> + !test_bit(MD_HAS_PPL, &mddev->flags)) {
> + mddev_suspend(mddev);
> + err = ppl_init_log(conf);
I didn't see you check if all rdev have valid ppl setting in ppl_load. Am I
missing anything? Is it possible some rdevs have ppl set, but some not. In the
case, we should just bail out.
Also check if this is raid5
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 0/7] Partial Parity Log for MD RAID 5
2017-02-21 19:43 [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
` (6 preceding siblings ...)
2017-02-21 19:44 ` [PATCH v4 7/7] raid5-ppl: runtime PPL enabling or disabling Artur Paszkiewicz
@ 2017-02-28 1:35 ` Shaohua Li
2017-03-01 16:12 ` Artur Paszkiewicz
7 siblings, 1 reply; 25+ messages in thread
From: Shaohua Li @ 2017-02-28 1:35 UTC (permalink / raw)
To: Artur Paszkiewicz; +Cc: shli, linux-raid
On Tue, Feb 21, 2017 at 08:43:54PM +0100, Artur Paszkiewicz wrote:
> This series of patches implements the Partial Parity Log for RAID5 arrays. The
> purpose of this feature is closing the RAID 5 Write Hole. It is a solution
> alternative to the existing raid5-cache, but the logging workflow and much of
> the implementation is based on it.
>
> The main differences compared to raid5-cache is that PPL is a distributed log -
> it is stored on array member drives in the metadata area and does not require a
> dedicated journaling drive. Write performance is reduced by up to 30%-40% but
> it scales with the number of drives in the array and the journaling drive does
> not become a bottleneck or a single point of failure. PPL does not protect from
> losing in-flight data, only from silent data corruption. More details about how
> the log works can be found in patches 3 and 5.
>
> This feature originated from Intel RSTe, which uses IMSM metadata. This
> patchset implements PPL for external metadata (specifically IMSM) as well as
> native MD v1.x metadata.
>
> Changes in mdadm are also required to make this fully usable. Patches for mdadm
> will be sent later.
Generally looks ok, I replied separatly. I'd like to make sure the new format
will be supported by Intel RSTe, and intel will continue working on this.
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 0/7] Partial Parity Log for MD RAID 5
2017-02-28 1:35 ` [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Shaohua Li
@ 2017-03-01 16:12 ` Artur Paszkiewicz
0 siblings, 0 replies; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-03-01 16:12 UTC (permalink / raw)
To: Shaohua Li; +Cc: shli, linux-raid
On 02/28/2017 02:35 AM, Shaohua Li wrote:
> On Tue, Feb 21, 2017 at 08:43:54PM +0100, Artur Paszkiewicz wrote:
>> This series of patches implements the Partial Parity Log for RAID5 arrays. The
>> purpose of this feature is closing the RAID 5 Write Hole. It is a solution
>> alternative to the existing raid5-cache, but the logging workflow and much of
>> the implementation is based on it.
>>
>> The main differences compared to raid5-cache is that PPL is a distributed log -
>> it is stored on array member drives in the metadata area and does not require a
>> dedicated journaling drive. Write performance is reduced by up to 30%-40% but
>> it scales with the number of drives in the array and the journaling drive does
>> not become a bottleneck or a single point of failure. PPL does not protect from
>> losing in-flight data, only from silent data corruption. More details about how
>> the log works can be found in patches 3 and 5.
>>
>> This feature originated from Intel RSTe, which uses IMSM metadata. This
>> patchset implements PPL for external metadata (specifically IMSM) as well as
>> native MD v1.x metadata.
>>
>> Changes in mdadm are also required to make this fully usable. Patches for mdadm
>> will be sent later.
>
> Generally looks ok, I replied separatly. I'd like to make sure the new format
> will be supported by Intel RSTe, and intel will continue working on this.
PPL for IMSM is going to be included in RSTe implementations starting
with the upcoming Xeon platforms and Intel will continue supporting and
maintaining it.
Thanks,
Artur
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 2/7] raid5: calculate partial parity for a stripe
2017-02-27 23:45 ` Shaohua Li
@ 2017-03-01 16:12 ` Artur Paszkiewicz
0 siblings, 0 replies; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-03-01 16:12 UTC (permalink / raw)
To: Shaohua Li; +Cc: shli, linux-raid
On 02/28/2017 12:45 AM, Shaohua Li wrote:
> On Tue, Feb 21, 2017 at 08:43:56PM +0100, Artur Paszkiewicz wrote:
>> Attach a page for holding the partial parity data to stripe_head.
>> Allocate it only if mddev has the MD_HAS_PPL flag set.
>>
>> Partial parity is the xor of not modified data chunks of a stripe and is
>> calculated as follows:
>>
>> - reconstruct-write case:
>> xor data from all not updated disks in a stripe
>>
>> - read-modify-write case:
>> xor old data and parity from all updated disks in a stripe
>>
>> Implement it using the async_tx API and integrate into raid_run_ops().
>> It must be called when we still have access to old data, so do it when
>> STRIPE_OP_BIODRAIN is set, but before ops_run_prexor5(). The result is
>> stored into sh->ppl_page.
>>
>> Partial parity is not meaningful for full stripe write and is not stored
>> in the log or used for recovery, so don't attempt to calculate it when
>> stripe has STRIPE_FULL_WRITE.
>>
>> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
>> ---
>> drivers/md/raid5.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>> drivers/md/raid5.h | 3 ++
>> 2 files changed, 103 insertions(+)
>>
>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
>> index 7b7722bb2e8d..02e02fe5b04e 100644
>> --- a/drivers/md/raid5.c
>> +++ b/drivers/md/raid5.c
>> @@ -463,6 +463,11 @@ static void shrink_buffers(struct stripe_head *sh)
>> sh->dev[i].page = NULL;
>> put_page(p);
>> }
>> +
>> + if (sh->ppl_page) {
>> + put_page(sh->ppl_page);
>> + sh->ppl_page = NULL;
>> + }
>> }
>>
>> static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
>> @@ -479,6 +484,13 @@ static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
>> sh->dev[i].page = page;
>> sh->dev[i].orig_page = page;
>> }
>> +
>> + if (test_bit(MD_HAS_PPL, &sh->raid_conf->mddev->flags)) {
>> + sh->ppl_page = alloc_page(gfp);
>> + if (!sh->ppl_page)
>> + return 1;
>> + }
>> +
>> return 0;
>> }
>>
>> @@ -1974,6 +1986,55 @@ static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu
>> &sh->ops.zero_sum_result, percpu->spare_page, &submit);
>> }
>>
>> +static struct dma_async_tx_descriptor *
>> +ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
>> + struct dma_async_tx_descriptor *tx)
>> +{
>> + int disks = sh->disks;
>> + struct page **xor_srcs = flex_array_get(percpu->scribble, 0);
>> + int count = 0, pd_idx = sh->pd_idx, i;
>> + struct async_submit_ctl submit;
>> +
>> + pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
>> +
>> + /*
>> + * Partial parity is the XOR of stripe data chunks that are not changed
>> + * during the write request. Depending on available data
>> + * (read-modify-write vs. reconstruct-write case) we calculate it
>> + * differently.
>> + */
>> + if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
>> + /* rmw: xor old data and parity from updated disks */
>> + for (i = disks; i--;) {
>> + struct r5dev *dev = &sh->dev[i];
>> + if (test_bit(R5_Wantdrain, &dev->flags) || i == pd_idx)
>> + xor_srcs[count++] = dev->page;
>> + }
>> + } else if (sh->reconstruct_state == reconstruct_state_drain_run) {
>> + /* rcw: xor data from all not updated disks */
>> + for (i = disks; i--;) {
>> + struct r5dev *dev = &sh->dev[i];
>> + if (test_bit(R5_UPTODATE, &dev->flags))
>> + xor_srcs[count++] = dev->page;
>> + }
>> + } else {
>> + return tx;
>> + }
>> +
>> + init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, tx, NULL, sh,
>> + flex_array_get(percpu->scribble, 0)
>> + + sizeof(struct page *) * (sh->disks + 2));
>> +
>> + if (count == 1)
>> + tx = async_memcpy(sh->ppl_page, xor_srcs[0], 0, 0, PAGE_SIZE,
>> + &submit);
>> + else
>> + tx = async_xor(sh->ppl_page, xor_srcs, 0, count, PAGE_SIZE,
>> + &submit);
>> +
>> + return tx;
>> +}
>
> Can you put this function to raid5-ppl.c? I'd like to keep all the log related
> out raid5.c if possible.
Sure, I'll move it if you prefer that, but I thought that it's good to
have all the ops_run_ functions in one place.
Thanks,
Artur
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 3/7] raid5-ppl: Partial Parity Log write logging implementation
2017-02-28 0:04 ` Shaohua Li
@ 2017-03-01 16:13 ` Artur Paszkiewicz
2017-03-01 17:51 ` Shaohua Li
0 siblings, 1 reply; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-03-01 16:13 UTC (permalink / raw)
To: Shaohua Li; +Cc: shli, linux-raid
On 02/28/2017 01:04 AM, Shaohua Li wrote:
> On Tue, Feb 21, 2017 at 08:43:57PM +0100, Artur Paszkiewicz wrote:
>> This implements the PPL write logging functionality. The description
>> of PPL is added to the documentation. More details can be found in the
>> comments in raid5-ppl.c.
>>
>> Put the PPL metadata structures to md_p.h because userspace tools
>> (mdadm) will also need to read/write PPL.
>>
>> Warn about using PPL with enabled disk volatile write-back cache for
>> now. It can be removed once disk cache flushing before writing PPL is
>> implemented.
>>
>> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
>> ---
>> Documentation/md/raid5-ppl.txt | 44 +++
>> drivers/md/Makefile | 2 +-
>> drivers/md/raid5-ppl.c | 617 +++++++++++++++++++++++++++++++++++++++++
>> drivers/md/raid5.c | 49 +++-
>> drivers/md/raid5.h | 8 +
>> include/uapi/linux/raid/md_p.h | 26 ++
>> 6 files changed, 738 insertions(+), 8 deletions(-)
>> create mode 100644 Documentation/md/raid5-ppl.txt
>> create mode 100644 drivers/md/raid5-ppl.c
>>
>> diff --git a/Documentation/md/raid5-ppl.txt b/Documentation/md/raid5-ppl.txt
>> new file mode 100644
>> index 000000000000..127072b09363
>> --- /dev/null
>> +++ b/Documentation/md/raid5-ppl.txt
>> @@ -0,0 +1,44 @@
>> +Partial Parity Log
>> +
>> +Partial Parity Log (PPL) is a feature available for RAID5 arrays. The issue
>> +addressed by PPL is that after a dirty shutdown, parity of a particular stripe
>> +may become inconsistent with data on other member disks. If the array is also
>> +in degraded state, there is no way to recalculate parity, because one of the
>> +disks is missing. This can lead to silent data corruption when rebuilding the
>> +array or using it is as degraded - data calculated from parity for array blocks
>> +that have not been touched by a write request during the unclean shutdown can
>> +be incorrect. Such condition is known as the RAID5 Write Hole. Because of
>> +this, md by default does not allow starting a dirty degraded array.
>> +
>> +Partial parity for a write operation is the XOR of stripe data chunks not
>> +modified by this write. It is just enough data needed for recovering from the
>> +write hole. XORing partial parity with the modified chunks produces parity for
>> +the stripe, consistent with its state before the write operation, regardless of
>> +which chunk writes have completed. If one of the not modified data disks of
>> +this stripe is missing, this updated parity can be used to recover its
>> +contents. PPL recovery is also performed when starting an array after an
>> +unclean shutdown and all disks are available, eliminating the need to resync
>> +the array. Because of this, using write-intent bitmap and PPL together is not
>> +supported.
>> +
>> +When handling a write request PPL writes partial parity before new data and
>> +parity are dispatched to disks. PPL is a distributed log - it is stored on
>> +array member drives in the metadata area, on the parity drive of a particular
>> +stripe. It does not require a dedicated journaling drive. Write performance is
>> +reduced by up to 30%-40% but it scales with the number of drives in the array
>> +and the journaling drive does not become a bottleneck or a single point of
>> +failure.
>> +
>> +Unlike raid5-cache, the other solution in md for closing the write hole, PPL is
>> +not a true journal. It does not protect from losing in-flight data, only from
>> +silent data corruption. If a dirty disk of a stripe is lost, no PPL recovery is
>> +performed for this stripe (parity is not updated). So it is possible to have
>> +arbitrary data in the written part of a stripe if that disk is lost. In such
>> +case the behavior is the same as in plain raid5.
>> +
>> +PPL is available for md version-1 metadata and external (specifically IMSM)
>> +metadata arrays. It can be enabled using mdadm option --consistency-policy=ppl.
>> +
>> +Currently, volatile write-back cache should be disabled on all member drives
>> +when using PPL. Otherwise it cannot guarantee consistency in case of power
>> +failure.
>> diff --git a/drivers/md/Makefile b/drivers/md/Makefile
>> index 3cbda1af87a0..4d48714ccc6b 100644
>> --- a/drivers/md/Makefile
>> +++ b/drivers/md/Makefile
>> @@ -18,7 +18,7 @@ dm-cache-cleaner-y += dm-cache-policy-cleaner.o
>> dm-era-y += dm-era-target.o
>> dm-verity-y += dm-verity-target.o
>> md-mod-y += md.o bitmap.o
>> -raid456-y += raid5.o raid5-cache.o
>> +raid456-y += raid5.o raid5-cache.o raid5-ppl.o
>>
>> # Note: link order is important. All raid personalities
>> # and must come before md.o, as they each initialise
>> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
>> new file mode 100644
>> index 000000000000..a00cabf1adf6
>> --- /dev/null
>> +++ b/drivers/md/raid5-ppl.c
>> @@ -0,0 +1,617 @@
>> +/*
>> + * Partial Parity Log for closing the RAID5 write hole
>> + * Copyright (c) 2017, Intel Corporation.
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope it will be useful, but WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
>> + * more details.
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/blkdev.h>
>> +#include <linux/slab.h>
>> +#include <linux/crc32c.h>
>> +#include <linux/raid/md_p.h>
>> +#include "md.h"
>> +#include "raid5.h"
>> +
>> +/*
>> + * PPL consists of a 4KB header (struct ppl_header) and at least 128KB for
>> + * partial parity data. The header contains an array of entries
>> + * (struct ppl_header_entry) which describe the logged write requests.
>> + * Partial parity for the entries comes after the header, written in the same
>> + * sequence as the entries:
>> + *
>> + * Header
>> + * entry0
>> + * ...
>> + * entryN
>> + * PP data
>> + * PP for entry0
>> + * ...
>> + * PP for entryN
>> + *
>> + * Every entry holds a checksum of its partial parity, the header also has a
>> + * checksum of the header itself. Entries for full stripes writes contain no
>> + * partial parity, they only mark the stripes for which parity should be
>> + * recalculated after an unclean shutdown.
>
> Please describe the disk format in details. I had trouble to understand
> ppl_log_stripe() and ppl_submit_iounit(), things like the ppl merge, full
> stripes handling.
OK, I will improve it, but more information about this is also in patch 5.
>> + *
>> + * A write request is always logged to the PPL instance stored on the parity
>> + * disk of the corresponding stripe. For each member disk there is one ppl_log
>> + * used to handle logging for this disk, independently from others. They are
>> + * grouped in child_logs array in struct ppl_conf, which is assigned to
>> + * r5conf->ppl and used in raid5 core.
>> + *
>> + * ppl_io_unit represents a full PPL write, header_page contains the ppl_header.
>> + * PPL entries for logged stripes are added in ppl_log_stripe(). A stripe can
>> + * be appended to the last entry if the chunks to write are the same, otherwise
>> + * a new entry is added. Checksums of entries are calculated incrementally as
>> + * stripes containing partial parity are being added to entries.
>> + * ppl_submit_iounit() calculates the checksum of the header and submits a bio
>> + * containing the header page and partial parity pages (sh->ppl_page) for all
>> + * stripes of the io_unit. When the PPL write completes, the stripes associated
>> + * with the io_unit are released and raid5d starts writing their data and
>> + * parity. When all stripes are written, the io_unit is freed and the next can
>> + * be submitted.
>> + *
>> + * An io_unit is used to gather stripes until it is submitted or becomes full
>> + * (if the maximum number of entries or size of PPL is reached). Another io_unit
>> + * can't be submitted until the previous has completed (PPL and stripe
>> + * data+parity is written). The log->io_list tracks all io_units of a log
>> + * (for a single member disk). New io_units are added to the end of the list
>> + * and the first io_unit is submitted, if it is not submitted already.
>> + * The current io_unit accepting new stripes is always at the end of the list.
>> + */
>> +
>> +struct ppl_conf {
>> + struct mddev *mddev;
>> +
>> + /* array of child logs, one for each raid disk */
>> + struct ppl_log *child_logs;
>> + int count;
>> +
>> + int block_size; /* the logical block size used for data_sector
>> + * in ppl_header_entry */
>> + u32 signature; /* raid array identifier */
>> + atomic64_t seq; /* current log write sequence number */
>> +
>> + struct kmem_cache *io_kc;
>> + mempool_t *io_pool;
>> + struct bio_set *bs;
>> + mempool_t *meta_pool;
>> +};
>> +
>> +struct ppl_log {
>> + struct ppl_conf *ppl_conf; /* shared between all log instances */
>> +
>> + struct md_rdev *rdev; /* array member disk associated with
>> + * this log instance */
>> + struct mutex io_mutex;
>> + struct ppl_io_unit *current_io; /* current io_unit accepting new data
>> + * always at the end of io_list */
>> + spinlock_t io_list_lock;
>> + struct list_head io_list; /* all io_units of this log */
>> + struct list_head no_mem_stripes;/* stripes to retry if failed to
>> + * allocate io_unit */
>> +};
>> +
>> +struct ppl_io_unit {
>> + struct ppl_log *log;
>> +
>> + struct page *header_page; /* for ppl_header */
>> +
>> + unsigned int entries_count; /* number of entries in ppl_header */
>> + unsigned int pp_size; /* total size current of partial parity */
>> +
>> + u64 seq; /* sequence number of this log write */
>> + struct list_head log_sibling; /* log->io_list */
>> +
>> + struct list_head stripe_list; /* stripes added to the io_unit */
>> + atomic_t pending_stripes; /* how many stripes not written to raid */
>> +
>> + bool submitted; /* true if write to log started */
>> +};
>> +
>> +static struct ppl_io_unit *ppl_new_iounit(struct ppl_log *log,
>> + struct stripe_head *sh)
>> +{
>> + struct ppl_conf *ppl_conf = log->ppl_conf;
>> + struct ppl_io_unit *io;
>> + struct ppl_header *pplhdr;
>> +
>> + io = mempool_alloc(ppl_conf->io_pool, GFP_ATOMIC);
>> + if (!io)
>> + return NULL;
>> +
>> + memset(io, 0, sizeof(*io));
>> + io->log = log;
>> + INIT_LIST_HEAD(&io->log_sibling);
>> + INIT_LIST_HEAD(&io->stripe_list);
>> + atomic_set(&io->pending_stripes, 0);
>> +
>> + io->header_page = mempool_alloc(ppl_conf->meta_pool, GFP_NOIO);
>> + pplhdr = page_address(io->header_page);
>> + clear_page(pplhdr);
>> + memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
>> + pplhdr->signature = cpu_to_le32(ppl_conf->signature);
>> +
>> + io->seq = atomic64_add_return(1, &ppl_conf->seq);
>> + pplhdr->generation = cpu_to_le64(io->seq);
>> +
>> + return io;
>> +}
>> +
>> +static int ppl_log_stripe(struct ppl_log *log, struct stripe_head *sh)
>> +{
>> + struct ppl_io_unit *io = log->current_io;
>> + struct ppl_header_entry *e = NULL;
>> + struct ppl_header *pplhdr;
>> + int i;
>> + sector_t data_sector = 0;
>> + int data_disks = 0;
>> + unsigned int entry_space = (log->rdev->ppl.size << 9) - PPL_HEADER_SIZE;
>> + struct r5conf *conf = sh->raid_conf;
>> +
>> + pr_debug("%s: stripe: %llu\n", __func__, (unsigned long long)sh->sector);
>> +
>> + /* check if current io_unit is full */
>> + if (io && (io->pp_size == entry_space ||
>> + io->entries_count == PPL_HDR_MAX_ENTRIES)) {
>> + pr_debug("%s: add io_unit blocked by seq: %llu\n",
>> + __func__, io->seq);
>> + io = NULL;
>> + }
>> +
>> + /* add a new unit if there is none or the current is full */
>> + if (!io) {
>> + io = ppl_new_iounit(log, sh);
>> + if (!io)
>> + return -ENOMEM;
>> + spin_lock_irq(&log->io_list_lock);
>> + list_add_tail(&io->log_sibling, &log->io_list);
>> + spin_unlock_irq(&log->io_list_lock);
>> +
>> + log->current_io = io;
>> + }
>> +
>> + for (i = 0; i < sh->disks; i++) {
>> + struct r5dev *dev = &sh->dev[i];
>> +
>> + if (i != sh->pd_idx && test_bit(R5_Wantwrite, &dev->flags)) {
>> + if (!data_disks || dev->sector < data_sector)
>> + data_sector = dev->sector;
>> + data_disks++;
>> + }
>> + }
>> + BUG_ON(!data_disks);
>> +
>> + pr_debug("%s: seq: %llu data_sector: %llu data_disks: %d\n", __func__,
>> + io->seq, (unsigned long long)data_sector, data_disks);
>> +
>> + pplhdr = page_address(io->header_page);
>> +
>> + if (io->entries_count > 0) {
>> + struct ppl_header_entry *last =
>> + &pplhdr->entries[io->entries_count - 1];
>> + u64 data_sector_last = le64_to_cpu(last->data_sector);
>> + u32 data_size_last = le32_to_cpu(last->data_size);
>> + u32 pp_size_last = le32_to_cpu(last->pp_size);
>> +
>> + /*
>> + * Check if we can merge with the last entry. Must be on
>> + * the same stripe and disks. Use bit shift and logarithm
>> + * to avoid 64-bit division.
>> + */
>> + if ((data_sector >> ilog2(conf->chunk_sectors) ==
>> + data_sector_last >> ilog2(conf->chunk_sectors)) &&
>> + ((pp_size_last == 0 &&
>> + test_bit(STRIPE_FULL_WRITE, &sh->state)) ||
>> + ((data_sector_last + (pp_size_last >> 9) == data_sector) &&
>> + (data_size_last == pp_size_last * data_disks))))
>
> please explain this part
This checks if the last and currently logged stripe_head are on the same
stripe and the disks to write are the same. The conditions are probably
more complicated than they should be, I'll try to simplify it.
>> + e = last;
>> + }
>> +
>> + if (!e) {
>> + e = &pplhdr->entries[io->entries_count++];
>> + e->data_sector = cpu_to_le64(data_sector);
>
> Don't really understand what's the data_sector for. Should this be stripe->sector?
This is the first raid sector of the ppl entry. It can be equal to
stripe->sector if the write starts at the first disk of the stripe. So
generally it is the sector of the first device in the stripe with
R5_Wantwrite of the first stripe in the ppl entry.
>> + e->parity_disk = cpu_to_le32(sh->pd_idx);
>> + e->checksum = cpu_to_le32(~0);
>> + }
>> +
>> + le32_add_cpu(&e->data_size, data_disks << PAGE_SHIFT);
>> +
>> + /* don't write any PP if full stripe write */
>> + if (!test_bit(STRIPE_FULL_WRITE, &sh->state)) {
>> + le32_add_cpu(&e->pp_size, PAGE_SIZE);
>> + io->pp_size += PAGE_SIZE;
>> + e->checksum = cpu_to_le32(crc32c_le(le32_to_cpu(e->checksum),
>> + page_address(sh->ppl_page),
>> + PAGE_SIZE));
>> + }
>> +
>> + list_add_tail(&sh->log_list, &io->stripe_list);
>> + atomic_inc(&io->pending_stripes);
>> + sh->ppl_log_io = io;
>> +
>> + return 0;
>> +}
>> +
>> +int ppl_write_stripe(struct ppl_conf *ppl_conf, struct stripe_head *sh)
>> +{
>> + struct ppl_log *log;
>> + struct ppl_io_unit *io = sh->ppl_log_io;
>> +
>> + if (io || test_bit(STRIPE_SYNCING, &sh->state) ||
>> + !test_bit(R5_Wantwrite, &sh->dev[sh->pd_idx].flags) ||
>> + !test_bit(R5_Insync, &sh->dev[sh->pd_idx].flags)) {
>> + clear_bit(STRIPE_LOG_TRAPPED, &sh->state);
>> + return -EAGAIN;
>> + }
>> +
>> + log = &ppl_conf->child_logs[sh->pd_idx];
>> +
>> + mutex_lock(&log->io_mutex);
>> +
>> + if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
>
> is the log->rdev check required?
Yes, log->rdev can be null if the member drive for this stripe's parity
is missing. Patch 6 ("support disk hot add/remove with PPL") makes it
more apparent.
>> + mutex_unlock(&log->io_mutex);
>> + return -EAGAIN;
>> + }
>> +
>> + set_bit(STRIPE_LOG_TRAPPED, &sh->state);
>> + clear_bit(STRIPE_DELAYED, &sh->state);
>> + atomic_inc(&sh->count);
>> +
>> + if (ppl_log_stripe(log, sh)) {
>> + spin_lock_irq(&log->io_list_lock);
>> + list_add_tail(&sh->log_list, &log->no_mem_stripes);
>> + spin_unlock_irq(&log->io_list_lock);
>> + }
>> +
>> + mutex_unlock(&log->io_mutex);
>> +
>> + return 0;
>> +}
>> +
>> +static void ppl_log_endio(struct bio *bio)
>> +{
>> + struct ppl_io_unit *io = bio->bi_private;
>> + struct ppl_log *log = io->log;
>> + struct ppl_conf *ppl_conf = log->ppl_conf;
>> + struct stripe_head *sh, *next;
>> +
>> + pr_debug("%s: seq: %llu\n", __func__, io->seq);
>> +
>> + if (bio->bi_error)
>> + md_error(ppl_conf->mddev, log->rdev);
>> +
>> + bio_put(bio);
>> + mempool_free(io->header_page, ppl_conf->meta_pool);
>> +
>> + list_for_each_entry_safe(sh, next, &io->stripe_list, log_list) {
>> + list_del_init(&sh->log_list);
>> +
>> + set_bit(STRIPE_HANDLE, &sh->state);
>> + raid5_release_stripe(sh);
>> + }
>> +}
>> +
>> +static void ppl_submit_iounit(struct ppl_io_unit *io)
>> +{
>> + struct ppl_log *log = io->log;
>> + struct ppl_conf *ppl_conf = log->ppl_conf;
>> + struct r5conf *conf = ppl_conf->mddev->private;
>> + struct ppl_header *pplhdr = page_address(io->header_page);
>> + struct bio *bio;
>> + struct stripe_head *sh;
>> + int i;
>> + struct bio_list bios = BIO_EMPTY_LIST;
>> + char b[BDEVNAME_SIZE];
>> +
>> + bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, ppl_conf->bs);
>> + bio->bi_private = io;
>> + bio->bi_end_io = ppl_log_endio;
>> + bio->bi_opf = REQ_OP_WRITE | REQ_FUA;
>> + bio->bi_bdev = log->rdev->bdev;
>> + bio->bi_iter.bi_sector = log->rdev->ppl.sector;
>> + bio_add_page(bio, io->header_page, PAGE_SIZE, 0);
>> + bio_list_add(&bios, bio);
>> +
>> + sh = list_first_entry(&io->stripe_list, struct stripe_head, log_list);
>> +
>> + for (i = 0; i < io->entries_count; i++) {
>> + struct ppl_header_entry *e = &pplhdr->entries[i];
>> + u32 pp_size = le32_to_cpu(e->pp_size);
>> + u32 data_size = le32_to_cpu(e->data_size);
>> + u64 data_sector = le64_to_cpu(e->data_sector);
>> + int stripes_count;
>> +
>> + if (pp_size > 0)
>> + stripes_count = pp_size >> PAGE_SHIFT;
>> + else
>> + stripes_count = (data_size /
>> + (conf->raid_disks -
>> + conf->max_degraded)) >> PAGE_SHIFT;
>
> please explain this part
The number of stripes of a ppl entry is equal to the size of its partial
parity divided by 4k, except when the stripes are STRIPE_FULL_WRITE -
then there is no partial parity, but the number of stripes is then equal
to the entry's data size / array data disks / 4k.
>> +
>> + while (stripes_count--) {
>> + /*
>> + * if entry without partial parity just skip its stripes
>> + * without adding pages to bio
>> + */
>> + if (pp_size > 0 &&
>> + !bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0)) {
>> + struct bio *prev = bio;
>> +
>> + bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES,
>> + ppl_conf->bs);
>
> The code keeps allocating bios but doesn't dispatch any yet. The bioset can't
> guarantee the allocation successes. To have the guarantee, we must make sure
> previous bios could finish.
Is it ok to submit the bio before allocating another from the same
bioset, without waiting for it to complete? The description for
bio_alloc_bioset() suggests this, if I understand it correctly: "Callers
that need to allocate more than 1 bio must always submit the previously
allocated bio for IO before attempting to allocate a new one."
>> + bio->bi_opf = prev->bi_opf;
>> + bio->bi_bdev = prev->bi_bdev;
>> + bio->bi_iter.bi_sector = bio_end_sector(prev);
>> + bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0);
>> + bio_chain(bio, prev);
>> + bio_list_add(&bios, bio);
>> + }
>> + sh = list_next_entry(sh, log_list);
>> + }
>> +
>> + pr_debug("%s: seq: %llu entry: %d data_sector: %llu pp_size: %u data_size: %u\n",
>> + __func__, io->seq, i, data_sector, pp_size, data_size);
>> +
>> + e->data_sector = cpu_to_le64(data_sector >>
>> + ilog2(ppl_conf->block_size >> 9));
>> + e->checksum = cpu_to_le32(~le32_to_cpu(e->checksum));
>> + }
>> +
>> + pplhdr->entries_count = cpu_to_le32(io->entries_count);
>> + pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PPL_HEADER_SIZE));
>
> so the checksum is ~crc32c, right? please doc in ppl_header_entry definition
Ok, I will add it to the descriptions for both header and entry checksums.
>> +
>> + while ((bio = bio_list_pop(&bios))) {
>> + pr_debug("%s: seq: %llu submit_bio() size: %u sector: %llu dev: %s\n",
>> + __func__, io->seq, bio->bi_iter.bi_size,
>> + (unsigned long long)bio->bi_iter.bi_sector,
>> + bdevname(bio->bi_bdev, b));
>> + submit_bio(bio);
>> + }
>> +}
>> +
>> +static void ppl_submit_current_io(struct ppl_log *log)
>> +{
>> + struct ppl_io_unit *io;
>> +
>> + spin_lock_irq(&log->io_list_lock);
>> +
>> + io = list_first_entry_or_null(&log->io_list, struct ppl_io_unit,
>> + log_sibling);
>> + if (io && io->submitted)
>> + io = NULL;
>> +
>> + spin_unlock_irq(&log->io_list_lock);
>> +
>> + if (io) {
>> + io->submitted = true;
>> +
>> + if (io == log->current_io)
>> + log->current_io = NULL;
>> +
>> + ppl_submit_iounit(io);
>> + }
>> +}
>> +
>> +void ppl_write_stripe_run(struct ppl_conf *ppl_conf)
>> +{
>> + struct ppl_log *log;
>> + int i;
>> +
>> + for (i = 0; i < ppl_conf->count; i++) {
>> + log = &ppl_conf->child_logs[i];
>> +
>> + mutex_lock(&log->io_mutex);
>> + ppl_submit_current_io(log);
>> + mutex_unlock(&log->io_mutex);
>> + }
>> +}
>> +
>> +static void ppl_io_unit_finished(struct ppl_io_unit *io)
>> +{
>> + struct ppl_log *log = io->log;
>> + unsigned long flags;
>> +
>> + pr_debug("%s: seq: %llu\n", __func__, io->seq);
>> +
>> + spin_lock_irqsave(&log->io_list_lock, flags);
>> +
>> + list_del(&io->log_sibling);
>> + mempool_free(io, log->ppl_conf->io_pool);
>> +
>> + if (!list_empty(&log->no_mem_stripes)) {
>> + struct stripe_head *sh = list_first_entry(&log->no_mem_stripes,
>> + struct stripe_head,
>> + log_list);
>> + list_del_init(&sh->log_list);
>> + set_bit(STRIPE_HANDLE, &sh->state);
>> + raid5_release_stripe(sh);
>> + }
>> +
>> + spin_unlock_irqrestore(&log->io_list_lock, flags);
>> +}
>> +
>> +void ppl_stripe_write_finished(struct stripe_head *sh)
>> +{
>> + struct ppl_io_unit *io;
>> +
>> + io = sh->ppl_log_io;
>> + sh->ppl_log_io = NULL;
>> +
>> + if (io && atomic_dec_and_test(&io->pending_stripes))
>> + ppl_io_unit_finished(io);
>> +}
>> +
>> +void ppl_exit_log(struct ppl_conf *ppl_conf)
>> +{
>> + kfree(ppl_conf->child_logs);
>> +
>> + mempool_destroy(ppl_conf->meta_pool);
>> + if (ppl_conf->bs)
>> + bioset_free(ppl_conf->bs);
>> + mempool_destroy(ppl_conf->io_pool);
>> + kmem_cache_destroy(ppl_conf->io_kc);
>> +
>> + kfree(ppl_conf);
>> +}
>> +
>> +static int ppl_validate_rdev(struct md_rdev *rdev)
>> +{
>> + char b[BDEVNAME_SIZE];
>> + int ppl_data_sectors;
>> + int ppl_size_new;
>> +
>> + /*
>> + * The configured PPL size must be enough to store
>> + * the header and (at the very least) partial parity
>> + * for one stripe. Round it down to ensure the data
>> + * space is cleanly divisible by stripe size.
>> + */
>> + ppl_data_sectors = rdev->ppl.size - (PPL_HEADER_SIZE >> 9);
>> +
>> + if (ppl_data_sectors > 0)
>> + ppl_data_sectors = rounddown(ppl_data_sectors, STRIPE_SECTORS);
>> +
>> + if (ppl_data_sectors <= 0) {
>> + pr_warn("md/raid:%s: PPL space too small on %s\n",
>> + mdname(rdev->mddev), bdevname(rdev->bdev, b));
>> + return -ENOSPC;
>> + }
>> +
>> + ppl_size_new = ppl_data_sectors + (PPL_HEADER_SIZE >> 9);
>> +
>> + if ((rdev->ppl.sector < rdev->data_offset &&
>> + rdev->ppl.sector + ppl_size_new > rdev->data_offset) ||
>> + (rdev->ppl.sector >= rdev->data_offset &&
>> + rdev->data_offset + rdev->sectors > rdev->ppl.sector)) {
>> + pr_warn("md/raid:%s: PPL space overlaps with data on %s\n",
>> + mdname(rdev->mddev), bdevname(rdev->bdev, b));
>> + return -EINVAL;
>> + }
>> +
>> + if (!rdev->mddev->external &&
>> + ((rdev->ppl.offset > 0 && rdev->ppl.offset < (rdev->sb_size >> 9)) ||
>> + (rdev->ppl.offset <= 0 && rdev->ppl.offset + ppl_size_new > 0))) {
>> + pr_warn("md/raid:%s: PPL space overlaps with superblock on %s\n",
>> + mdname(rdev->mddev), bdevname(rdev->bdev, b));
>> + return -EINVAL;
>> + }
>> +
>> + rdev->ppl.size = ppl_size_new;
>> +
>> + return 0;
>> +}
>> +
>> +int ppl_init_log(struct r5conf *conf)
>> +{
>> + struct ppl_conf *ppl_conf;
>> + struct mddev *mddev = conf->mddev;
>> + int ret = 0;
>> + int i;
>> + bool need_cache_flush;
>> +
>> + if (PAGE_SIZE != 4096)
>> + return -EINVAL;
>> +
>> + if (mddev->bitmap_info.file || mddev->bitmap_info.offset) {
>> + pr_warn("md/raid:%s PPL is not compatible with bitmap\n",
>> + mdname(mddev));
>> + return -EINVAL;
>> + }
>> +
>> + if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
>> + pr_warn("md/raid:%s PPL is not compatible with journal\n",
>> + mdname(mddev));
>> + return -EINVAL;
>> + }
>
> shouldn't these two checks be put into md.c, which we load the rdev?
Then they would not be performed for external metadata and when enabling
ppl at runtime. I think we need this in a central place where ppl is
started.
>> +
>> + ppl_conf = kzalloc(sizeof(struct ppl_conf), GFP_KERNEL);
>> + if (!ppl_conf)
>> + return -ENOMEM;
>> +
>> + ppl_conf->io_kc = KMEM_CACHE(ppl_io_unit, 0);
>> + if (!ppl_conf->io_kc) {
>> + ret = -EINVAL;
>> + goto err;
>> + }
>> +
>> + ppl_conf->io_pool = mempool_create_slab_pool(conf->raid_disks, ppl_conf->io_kc);
>> + if (!ppl_conf->io_pool) {
>> + ret = -EINVAL;
>> + goto err;
>> + }
>> +
>> + ppl_conf->bs = bioset_create(conf->raid_disks, 0);
>> + if (!ppl_conf->bs) {
>> + ret = -EINVAL;
>> + goto err;
>> + }
>> +
>> + ppl_conf->meta_pool = mempool_create_page_pool(conf->raid_disks, 0);
>> + if (!ppl_conf->meta_pool) {
>> + ret = -EINVAL;
>> + goto err;
>> + }
>> +
>> + ppl_conf->mddev = mddev;
>> + ppl_conf->count = conf->raid_disks;
>> + ppl_conf->child_logs = kcalloc(ppl_conf->count, sizeof(struct ppl_log),
>> + GFP_KERNEL);
>> + if (!ppl_conf->child_logs) {
>> + ret = -ENOMEM;
>> + goto err;
>> + }
>> +
>> + atomic64_set(&ppl_conf->seq, 0);
>> +
>> + if (!mddev->external) {
>> + ppl_conf->signature = ~crc32c_le(~0, mddev->uuid, sizeof(mddev->uuid));
>> + ppl_conf->block_size = 512;
>> + } else {
>> + ppl_conf->block_size = queue_logical_block_size(mddev->queue);
>> + }
>
> Can we always set block_size 512? Don't really understand this part.
For native md arrays we can use 512 byte sectors, like in the rest of md
metadata, but for imsm the values in ppl_header_entry.data_sector must
be in logical sectors, due to compatibility with UEFI and Windows.
>> +
>> + for (i = 0; i < ppl_conf->count; i++) {
>> + struct ppl_log *log = &ppl_conf->child_logs[i];
>> + struct md_rdev *rdev = conf->disks[i].rdev;
>> +
>> + mutex_init(&log->io_mutex);
>> + spin_lock_init(&log->io_list_lock);
>> + INIT_LIST_HEAD(&log->io_list);
>> + INIT_LIST_HEAD(&log->no_mem_stripes);
>> +
>> + log->ppl_conf = ppl_conf;
>> + log->rdev = rdev;
>> +
>> + if (rdev) {
>> + struct request_queue *q;
>> +
>> + ret = ppl_validate_rdev(rdev);
>> + if (ret)
>> + goto err;
>> +
>> + q = bdev_get_queue(rdev->bdev);
>> + if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
>> + need_cache_flush = true;
>> + }
>> + }
>> +
>> + if (need_cache_flush)
>> + pr_warn("md/raid:%s: Volatile write-back cache should be disabled on all member drives when using PPL!\n",
>> + mdname(mddev));
>> +
>> + conf->ppl = ppl_conf;
>> +
>> + return 0;
>> +err:
>> + ppl_exit_log(ppl_conf);
>> + return ret;
>> +}
>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
>> index 02e02fe5b04e..21440b594878 100644
>> --- a/drivers/md/raid5.c
>> +++ b/drivers/md/raid5.c
>> @@ -739,7 +739,7 @@ static bool stripe_can_batch(struct stripe_head *sh)
>> {
>> struct r5conf *conf = sh->raid_conf;
>>
>> - if (conf->log)
>> + if (conf->log || conf->ppl)
>> return false;
>
> Maybe add a new inline function into raid5-log.h
OK, I will move it.
>> return test_bit(STRIPE_BATCH_READY, &sh->state) &&
>> !test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
>> @@ -936,6 +936,9 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
>> }
>> }
>>
>> + if (conf->ppl && ppl_write_stripe(conf->ppl, sh) == 0)
>> + return;
>
> please put the one and the above raid5-cache part into a separate function into raid5-log.h
>
>> +
>> for (i = disks; i--; ) {
>> int op, op_flags = 0;
>> int replace_only = 0;
>> @@ -3308,6 +3311,16 @@ static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
>> &dd_idx, sh);
>> }
>>
>> +static void log_stripe_write_finished(struct stripe_head *sh)
>> +{
>> + struct r5conf *conf = sh->raid_conf;
>> +
>> + if (conf->log)
>> + r5l_stripe_write_finished(sh);
>> + else if (conf->ppl)
>> + ppl_stripe_write_finished(sh);
>> +}
>
> please put this into raid5-log.h
>
>> +
>> static void
>> handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
>> struct stripe_head_state *s, int disks,
>> @@ -3347,7 +3360,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
>> if (bi)
>> bitmap_end = 1;
>>
>> - r5l_stripe_write_finished(sh);
>> + log_stripe_write_finished(sh);
>>
>> if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
>> wake_up(&conf->wait_for_overlap);
>> @@ -3766,7 +3779,7 @@ static void handle_stripe_clean_event(struct r5conf *conf,
>> discard_pending = 1;
>> }
>>
>> - r5l_stripe_write_finished(sh);
>> + log_stripe_write_finished(sh);
>>
>> if (!discard_pending &&
>> test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
>> @@ -4756,7 +4769,7 @@ static void handle_stripe(struct stripe_head *sh)
>>
>> if (s.just_cached)
>> r5c_handle_cached_data_endio(conf, sh, disks, &s.return_bi);
>> - r5l_stripe_write_finished(sh);
>> + log_stripe_write_finished(sh);
>>
>> /* Now we might consider reading some blocks, either to check/generate
>> * parity, or to satisfy requests
>> @@ -6120,6 +6133,14 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
>> return handled;
>> }
>>
>> +static void log_write_stripe_run(struct r5conf *conf)
>> +{
>> + if (conf->log)
>> + r5l_write_stripe_run(conf->log);
>> + else if (conf->ppl)
>> + ppl_write_stripe_run(conf->ppl);
>> +}
>
> ditto
>
>> +
>> static int handle_active_stripes(struct r5conf *conf, int group,
>> struct r5worker *worker,
>> struct list_head *temp_inactive_list)
>> @@ -6157,7 +6178,7 @@ static int handle_active_stripes(struct r5conf *conf, int group,
>>
>> for (i = 0; i < batch_size; i++)
>> handle_stripe(batch[i]);
>> - r5l_write_stripe_run(conf->log);
>> + log_write_stripe_run(conf);
>>
>> cond_resched();
>>
>> @@ -6735,6 +6756,8 @@ static void free_conf(struct r5conf *conf)
>>
>> if (conf->log)
>> r5l_exit_log(conf->log);
>> + if (conf->ppl)
>> + ppl_exit_log(conf->ppl);
>
> Ditto
>
>> if (conf->shrinker.nr_deferred)
>> unregister_shrinker(&conf->shrinker);
>>
>> @@ -7196,6 +7219,13 @@ static int raid5_run(struct mddev *mddev)
>> BUG_ON(mddev->delta_disks != 0);
>> }
>>
>> + if (test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
>> + test_bit(MD_HAS_PPL, &mddev->flags)) {
>> + pr_warn("md/raid:%s: using journal device and PPL not allowed - disabling PPL\n",
>> + mdname(mddev));
>> + clear_bit(MD_HAS_PPL, &mddev->flags);
>> + }
>> +
>> if (mddev->private == NULL)
>> conf = setup_conf(mddev);
>> else
>> @@ -7422,6 +7452,11 @@ static int raid5_run(struct mddev *mddev)
>> mdname(mddev), bdevname(journal_dev->bdev, b));
>> if (r5l_init_log(conf, journal_dev))
>> goto abort;
>> + } else if (test_bit(MD_HAS_PPL, &mddev->flags)) {
>> + pr_debug("md/raid:%s: enabling distributed Partial Parity Log\n",
>> + mdname(mddev));
>> + if (ppl_init_log(conf))
>> + goto abort;
>> }
>
> Ditto, if possible
>
>>
>> return 0;
>> @@ -7690,7 +7725,7 @@ static int raid5_resize(struct mddev *mddev, sector_t sectors)
>> sector_t newsize;
>> struct r5conf *conf = mddev->private;
>>
>> - if (conf->log)
>> + if (conf->log || conf->ppl)
>> return -EINVAL;
>> sectors &= ~((sector_t)conf->chunk_sectors - 1);
>> newsize = raid5_size(mddev, sectors, mddev->raid_disks);
>> @@ -7743,7 +7778,7 @@ static int check_reshape(struct mddev *mddev)
>> {
>> struct r5conf *conf = mddev->private;
>>
>> - if (conf->log)
>> + if (conf->log || conf->ppl)
>
> there are other places we check conf->log. like stripe_can_batch(), I think the
> ppl code can't hanel batch right now.
Yes, I added this also in stripe_can_batch(). I checked all other places
where conf->log is used and I think that everything is covered in this
patchset, but I will check again.
>> return -EINVAL;
>> if (mddev->delta_disks == 0 &&
>> mddev->new_layout == mddev->layout &&
>> diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
>> index 3cc4cb28f7e6..f915a7a0e752 100644
>> --- a/drivers/md/raid5.h
>> +++ b/drivers/md/raid5.h
>> @@ -230,6 +230,7 @@ struct stripe_head {
>> struct list_head r5c; /* for r5c_cache->stripe_in_journal */
>>
>> struct page *ppl_page; /* partial parity of this stripe */
>> + struct ppl_io_unit *ppl_log_io;
>
> Maybe we should put the ppl fields and raid5 fields to a union
Good idea, will do.
>> /**
>> * struct stripe_operations
>> * @target - STRIPE_OP_COMPUTE_BLK target
>> @@ -689,6 +690,7 @@ struct r5conf {
>> int group_cnt;
>> int worker_cnt_per_group;
>> struct r5l_log *log;
>> + struct ppl_conf *ppl;
>
> Maybe use void * log_private, so works for both raid5-cache and ppl
Do you mean replace "struct ppl_conf *ppl" with "void *log_private"?
>>
>> struct bio_list pending_bios;
>> spinlock_t pending_bios_lock;
>> @@ -798,4 +800,10 @@ extern void r5c_check_cached_full_stripe(struct r5conf *conf);
>> extern struct md_sysfs_entry r5c_journal_mode;
>> extern void r5c_update_on_rdev_error(struct mddev *mddev);
>> extern bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect);
>> +
>> +extern int ppl_init_log(struct r5conf *conf);
>> +extern void ppl_exit_log(struct ppl_conf *log);
>> +extern int ppl_write_stripe(struct ppl_conf *log, struct stripe_head *sh);
>> +extern void ppl_write_stripe_run(struct ppl_conf *log);
>> +extern void ppl_stripe_write_finished(struct stripe_head *sh);
>
> These part and the raid5 part should be put into raid5-log.h
>
>> #endif
>> diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
>> index fe2112810c43..2c28711cc5f1 100644
>> --- a/include/uapi/linux/raid/md_p.h
>> +++ b/include/uapi/linux/raid/md_p.h
>> @@ -398,4 +398,30 @@ struct r5l_meta_block {
>>
>> #define R5LOG_VERSION 0x1
>> #define R5LOG_MAGIC 0x6433c509
>> +
>> +struct ppl_header_entry {
>> + __le64 data_sector; /* Raid sector of the new data */
>> + __le32 pp_size; /* Length of partial parity */
>> + __le32 data_size; /* Length of data */
>> + __le32 parity_disk; /* Member disk containing parity */
>> + __le32 checksum; /* Checksum of this entry */
>
> So we changed the disk format. Will this new format be put into IMSM standard?
> Do we have a version to verify the old/new format for IMSM?
Yes, this will be included in IMSM. The platforms with support for this
are not yet released, so minor changes to the format were still
possible. This can be considered the first version of the PPL metadata
format. In the future if there will be any changes I think that for
example a version field could be inserted in place of
ppl_header.padding, which is currently always set to 0.
Thanks,
Artur
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 4/7] md: add sysfs entries for PPL
2017-02-28 0:37 ` Shaohua Li
@ 2017-03-01 16:13 ` Artur Paszkiewicz
0 siblings, 0 replies; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-03-01 16:13 UTC (permalink / raw)
To: Shaohua Li; +Cc: shli, linux-raid
On 02/28/2017 01:37 AM, Shaohua Li wrote:
> On Tue, Feb 21, 2017 at 08:43:58PM +0100, Artur Paszkiewicz wrote:
>> Add 'consistency_policy' attribute for array. It indicates how the array
>> maintains consistency in case of unexpected shutdown.
>>
>> Add 'ppl_sector' and 'ppl_size' for rdev, which describe the location
>> and size of the PPL space on the device. They can't be changed for
>> active members if the array is started and PPL is enabled, so in the
>> setter functions only basic checks are performed. More checks are done
>> in ppl_validate_rdev() when starting the log.
>>
>> These attributes are writable to allow enabling PPL for external
>> metadata arrays and (later) to enable/disable PPL for a running array.
>>
>> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
>> ---
>> Documentation/admin-guide/md.rst | 32 ++++++++++-
>> drivers/md/md.c | 115 +++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 144 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst
>> index 1e61bf50595c..84de718f24a4 100644
>> --- a/Documentation/admin-guide/md.rst
>> +++ b/Documentation/admin-guide/md.rst
>> @@ -276,14 +276,14 @@ All md devices contain:
>> array creation it will default to 0, though starting the array as
>> ``clean`` will set it much larger.
>>
>> - new_dev
>> + new_dev
>> This file can be written but not read. The value written should
>> be a block device number as major:minor. e.g. 8:0
>> This will cause that device to be attached to the array, if it is
>> available. It will then appear at md/dev-XXX (depending on the
>> name of the device) and further configuration is then possible.
>>
>> - safe_mode_delay
>> + safe_mode_delay
>> When an md array has seen no write requests for a certain period
>> of time, it will be marked as ``clean``. When another write
>> request arrives, the array is marked as ``dirty`` before the write
>> @@ -292,7 +292,7 @@ All md devices contain:
>> period as a number of seconds. The default is 200msec (0.200).
>> Writing a value of 0 disables safemode.
>>
>> - array_state
>> + array_state
>> This file contains a single word which describes the current
>> state of the array. In many cases, the state can be set by
>> writing the word for the desired state, however some states
>> @@ -401,7 +401,30 @@ All md devices contain:
>> once the array becomes non-degraded, and this fact has been
>> recorded in the metadata.
>>
>> + consistency_policy
>> + This indicates how the array maintains consistency in case of unexpected
>> + shutdown. It can be:
>>
>> + none
>> + Array has no redundancy information, e.g. raid0, linear.
>> +
>> + resync
>> + Full resync is performed and all redundancy is regenerated when the
>> + array is started after unclean shutdown.
>> +
>> + bitmap
>> + Resync assisted by a write-intent bitmap.
>> +
>> + journal
>> + For raid4/5/6, journal device is used to log transactions and replay
>> + after unclean shutdown.
>> +
>> + ppl
>> + For raid5 only, Partial Parity Log is used to close the write hole and
>> + eliminate resync.
>> +
>> + The accepted values when writing to this file are ``ppl`` and ``resync``,
>> + used to enable and disable PPL.
>>
>>
>> As component devices are added to an md array, they appear in the ``md``
>> @@ -563,6 +586,9 @@ Each directory contains:
>> adds bad blocks without acknowledging them. This is largely
>> for testing.
>>
>> + ppl_sector, ppl_size
>> + Location and size (in sectors) of the space used for Partial Parity Log
>> + on this device.
>>
>>
>> An active md device will also contain an entry for each active device
>> diff --git a/drivers/md/md.c b/drivers/md/md.c
>> index c2028007b209..3ff979d538d4 100644
>> --- a/drivers/md/md.c
>> +++ b/drivers/md/md.c
>> @@ -3157,6 +3157,78 @@ static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)
>> static struct rdev_sysfs_entry rdev_unack_bad_blocks =
>> __ATTR(unacknowledged_bad_blocks, S_IRUGO|S_IWUSR, ubb_show, ubb_store);
>>
>> +static ssize_t
>> +ppl_sector_show(struct md_rdev *rdev, char *page)
>> +{
>> + return sprintf(page, "%llu\n", (unsigned long long)rdev->ppl.sector);
>> +}
>> +
>> +static ssize_t
>> +ppl_sector_store(struct md_rdev *rdev, const char *buf, size_t len)
>> +{
>> + unsigned long long sector;
>> +
>> + if (kstrtoull(buf, 10, §or) < 0)
>> + return -EINVAL;
>
> Maybe use base 0 to be more friendly
OK, good idea.
>> + if (sector != (sector_t)sector)
>> + return -EINVAL;
>> +
>> + if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
>> + rdev->raid_disk >= 0)
>> + return -EBUSY;
>> +
>> + if (rdev->mddev->persistent) {
>> + if (rdev->mddev->major_version == 0)
>> + return -EINVAL;
>> + if ((sector > rdev->sb_start &&
>> + sector - rdev->sb_start > S16_MAX) ||
>> + (sector < rdev->sb_start &&
>> + rdev->sb_start - sector > -S16_MIN))
>> + return -EINVAL;
>
> Don't check if the address overlaps with data?
It is checked in ppl_validate_rdev() when enabling ppl or adding a disk
to an array with ppl.
>> + rdev->ppl.offset = sector - rdev->sb_start;
>> + } else if (!rdev->mddev->external) {
>> + return -EBUSY;
>> + }
>
> generally we don't use {} for single line code
I thought this conforms to the coding-style doc? It says: "This does not
apply if only one branch of a conditional statement is a single
statement; in the latter case use braces in both branches"
Thanks,
Artur
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 5/7] raid5-ppl: load and recover the log
2017-02-28 1:12 ` Shaohua Li
@ 2017-03-01 16:14 ` Artur Paszkiewicz
2017-03-01 17:59 ` Shaohua Li
0 siblings, 1 reply; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-03-01 16:14 UTC (permalink / raw)
To: Shaohua Li; +Cc: shli, linux-raid
On 02/28/2017 02:12 AM, Shaohua Li wrote:
> On Tue, Feb 21, 2017 at 08:43:59PM +0100, Artur Paszkiewicz wrote:
>> Load the log from each disk when starting the array and recover if the
>> array is dirty.
>>
>> The initial empty PPL is written by mdadm. When loading the log we
>> verify the header checksum and signature. For external metadata arrays
>> the signature is verified in userspace, so here we read it from the
>> header, verifying only if it matches on all disks, and use it later when
>> writing PPL.
>>
>> In addition to the header checksum, each header entry also contains a
>> checksum of its partial parity data. If the header is valid, recovery is
>> performed for each entry until an invalid entry is found. If the array
>> is not degraded and recovery using PPL fully succeeds, there is no need
>> to resync the array because data and parity will be consistent, so in
>> this case resync will be disabled.
>>
>> Due to compatibility with IMSM implementations on other systems, we
>> can't assume that the recovery data block size is always 4K. Writes
>> generated by MD raid5 don't have this issue, but when recovering PPL
>> written in other environments it is possible to have entries with
>> 512-byte sector granularity. The recovery code takes this into account
>> and also the logical sector size of the underlying drives.
>>
>> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
>> ---
>> drivers/md/raid5-ppl.c | 483 +++++++++++++++++++++++++++++++++++++++++++++++++
>> drivers/md/raid5.c | 5 +-
>> 2 files changed, 487 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
>> index a00cabf1adf6..a7693353243a 100644
>> --- a/drivers/md/raid5-ppl.c
>> +++ b/drivers/md/raid5-ppl.c
>> @@ -16,6 +16,7 @@
>> #include <linux/blkdev.h>
>> #include <linux/slab.h>
>> #include <linux/crc32c.h>
>> +#include <linux/async_tx.h>
>> #include <linux/raid/md_p.h>
>> #include "md.h"
>> #include "raid5.h"
>> @@ -84,6 +85,10 @@ struct ppl_conf {
>> mempool_t *io_pool;
>> struct bio_set *bs;
>> mempool_t *meta_pool;
>> +
>> + /* used only for recovery */
>> + int recovered_entries;
>> + int mismatch_count;
>> };
>>
>> struct ppl_log {
>> @@ -450,6 +455,467 @@ void ppl_stripe_write_finished(struct stripe_head *sh)
>> ppl_io_unit_finished(io);
>> }
>>
>> +static void ppl_xor(int size, struct page *page1, struct page *page2,
>> + struct page *page_result)
>> +{
>> + struct async_submit_ctl submit;
>> + struct dma_async_tx_descriptor *tx;
>> + struct page *xor_srcs[] = { page1, page2 };
>> +
>> + init_async_submit(&submit, ASYNC_TX_ACK|ASYNC_TX_XOR_DROP_DST,
>> + NULL, NULL, NULL, NULL);
>> + tx = async_xor(page_result, xor_srcs, 0, 2, size, &submit);
>> +
>> + async_tx_quiesce(&tx);
>> +}
>> +
>> +/*
>> + * PPL recovery strategy: xor partial parity and data from all modified data
>> + * disks within a stripe and write the result as the new stripe parity. If all
>> + * stripe data disks are modified (full stripe write), no partial parity is
>> + * available, so just xor the data disks.
>> + *
>> + * Recovery of a PPL entry shall occur only if all modified data disks are
>> + * available and read from all of them succeeds.
>> + *
>> + * A PPL entry applies to a stripe, partial parity size for an entry is at most
>> + * the size of the chunk. Examples of possible cases for a single entry:
>> + *
>> + * case 0: single data disk write:
>> + * data0 data1 data2 ppl parity
>> + * +--------+--------+--------+ +--------------------+
>> + * | ------ | ------ | ------ | +----+ | (no change) |
>> + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
>> + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
>> + * | ------ | ------ | ------ | +----+ | (no change) |
>> + * +--------+--------+--------+ +--------------------+
>> + * pp_size = data_size
>> + *
>> + * case 1: more than one data disk write:
>> + * data0 data1 data2 ppl parity
>> + * +--------+--------+--------+ +--------------------+
>> + * | ------ | ------ | ------ | +----+ | (no change) |
>> + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
>> + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
>> + * | ------ | ------ | ------ | +----+ | (no change) |
>> + * +--------+--------+--------+ +--------------------+
>> + * pp_size = data_size / modified_data_disks
>> + *
>> + * case 2: write to all data disks (also full stripe write):
>> + * data0 data1 data2 parity
>> + * +--------+--------+--------+ +--------------------+
>> + * | ------ | ------ | ------ | | (no change) |
>> + * | -data- | -data- | -data- | --------> | xor all data |
>> + * | ------ | ------ | ------ | --------> | (no change) |
>> + * | ------ | ------ | ------ | | (no change) |
>> + * +--------+--------+--------+ +--------------------+
>> + * pp_size = 0
>> + *
>> + * The following cases are possible only in other implementations. The recovery
>> + * code can handle them, but they are not generated at runtime because they can
>> + * be reduced to cases 0, 1 and 2:
>> + *
>> + * case 3:
>> + * data0 data1 data2 ppl parity
>> + * +--------+--------+--------+ +----+ +--------------------+
>> + * | ------ | -data- | -data- | | pp | | data1 ^ data2 ^ pp |
>> + * | ------ | -data- | -data- | | pp | -> | data1 ^ data2 ^ pp |
>> + * | -data- | -data- | -data- | | -- | -> | xor all data |
>> + * | -data- | -data- | ------ | | pp | | data0 ^ data1 ^ pp |
>> + * +--------+--------+--------+ +----+ +--------------------+
>> + * pp_size = chunk_size
>> + *
>> + * case 4:
>> + * data0 data1 data2 ppl parity
>> + * +--------+--------+--------+ +----+ +--------------------+
>> + * | ------ | -data- | ------ | | pp | | data1 ^ pp |
>> + * | ------ | ------ | ------ | | -- | -> | (no change) |
>> + * | ------ | ------ | ------ | | -- | -> | (no change) |
>> + * | -data- | ------ | ------ | | pp | | data0 ^ pp |
>> + * +--------+--------+--------+ +----+ +--------------------+
>> + * pp_size = chunk_size
>> + */
>> +static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
>> + sector_t ppl_sector)
>> +{
>> + struct ppl_conf *ppl_conf = log->ppl_conf;
>> + struct mddev *mddev = ppl_conf->mddev;
>> + struct r5conf *conf = mddev->private;
>> + int block_size = ppl_conf->block_size;
>> + struct page *pages;
>> + struct page *page1;
>> + struct page *page2;
>> + sector_t r_sector_first;
>> + sector_t r_sector_last;
>> + int strip_sectors;
>> + int data_disks;
>> + int i;
>> + int ret = 0;
>> + char b[BDEVNAME_SIZE];
>> + unsigned int pp_size = le32_to_cpu(e->pp_size);
>> + unsigned int data_size = le32_to_cpu(e->data_size);
>> +
>> + r_sector_first = le64_to_cpu(e->data_sector) * (block_size >> 9);
>> +
>> + if ((pp_size >> 9) < conf->chunk_sectors) {
>> + if (pp_size > 0) {
>> + data_disks = data_size / pp_size;
>> + strip_sectors = pp_size >> 9;
>> + } else {
>> + data_disks = conf->raid_disks - conf->max_degraded;
>> + strip_sectors = (data_size >> 9) / data_disks;
>> + }
>> + r_sector_last = r_sector_first +
>> + (data_disks - 1) * conf->chunk_sectors +
>> + strip_sectors;
>> + } else {
>> + data_disks = conf->raid_disks - conf->max_degraded;
>> + strip_sectors = conf->chunk_sectors;
>> + r_sector_last = r_sector_first + (data_size >> 9);
>> + }
>> +
>> + pages = alloc_pages(GFP_KERNEL, 1);
>
> order != 0 allocation should be avoid if possible. Here sounds not necessary
OK, I will allocate and free them separately.
>> + if (!pages)
>> + return -ENOMEM;
>> + page1 = pages;
>> + page2 = pages + 1;
>> +
>> + pr_debug("%s: array sector first: %llu last: %llu\n", __func__,
>> + (unsigned long long)r_sector_first,
>> + (unsigned long long)r_sector_last);
>> +
>> + /* if start and end is 4k aligned, use a 4k block */
>> + if (block_size == 512 &&
>> + (r_sector_first & (STRIPE_SECTORS - 1)) == 0 &&
>> + (r_sector_last & (STRIPE_SECTORS - 1)) == 0)
>> + block_size = STRIPE_SIZE;
>> +
>> + /* iterate through blocks in strip */
>> + for (i = 0; i < strip_sectors; i += (block_size >> 9)) {
>> + bool update_parity = false;
>> + sector_t parity_sector;
>> + struct md_rdev *parity_rdev;
>> + struct stripe_head sh;
>> + int disk;
>> + int indent = 0;
>> +
>> + pr_debug("%s:%*s iter %d start\n", __func__, indent, "", i);
>> + indent += 2;
>> +
>> + memset(page_address(page1), 0, PAGE_SIZE);
>> +
>> + /* iterate through data member disks */
>> + for (disk = 0; disk < data_disks; disk++) {
>> + int dd_idx;
>> + struct md_rdev *rdev;
>> + sector_t sector;
>> + sector_t r_sector = r_sector_first + i +
>> + (disk * conf->chunk_sectors);
>> +
>> + pr_debug("%s:%*s data member disk %d start\n",
>> + __func__, indent, "", disk);
>> + indent += 2;
>> +
>> + if (r_sector >= r_sector_last) {
>> + pr_debug("%s:%*s array sector %llu doesn't need parity update\n",
>> + __func__, indent, "",
>> + (unsigned long long)r_sector);
>> + indent -= 2;
>> + continue;
>> + }
>> +
>> + update_parity = true;
>> +
>> + /* map raid sector to member disk */
>> + sector = raid5_compute_sector(conf, r_sector, 0,
>> + &dd_idx, NULL);
>> + pr_debug("%s:%*s processing array sector %llu => data member disk %d, sector %llu\n",
>> + __func__, indent, "",
>> + (unsigned long long)r_sector, dd_idx,
>> + (unsigned long long)sector);
>> +
>> + rdev = conf->disks[dd_idx].rdev;
>> + if (!rdev) {
>> + pr_debug("%s:%*s data member disk %d missing\n",
>> + __func__, indent, "", dd_idx);
>> + update_parity = false;
>> + break;
>> + }
>> +
>> + pr_debug("%s:%*s reading data member disk %s sector %llu\n",
>> + __func__, indent, "", bdevname(rdev->bdev, b),
>> + (unsigned long long)sector);
>> + if (!sync_page_io(rdev, sector, block_size, page2,
>> + REQ_OP_READ, 0, false)) {
>> + md_error(mddev, rdev);
>> + pr_debug("%s:%*s read failed!\n", __func__,
>> + indent, "");
>> + ret = -EIO;
>> + goto out;
>> + }
>> +
>> + ppl_xor(block_size, page1, page2, page1);
>> +
>> + indent -= 2;
>> + }
>> +
>> + if (!update_parity)
>> + continue;
>> +
>> + if (pp_size > 0) {
>> + pr_debug("%s:%*s reading pp disk sector %llu\n",
>> + __func__, indent, "",
>> + (unsigned long long)(ppl_sector + i));
>> + if (!sync_page_io(log->rdev,
>> + ppl_sector - log->rdev->data_offset + i,
>> + block_size, page2, REQ_OP_READ, 0,
>> + false)) {
>> + pr_debug("%s:%*s read failed!\n", __func__,
>> + indent, "");
>> + md_error(mddev, log->rdev);
>> + ret = -EIO;
>> + goto out;
>> + }
>> +
>> + ppl_xor(block_size, page1, page2, page1);
>> + }
>> +
>> + /* map raid sector to parity disk */
>> + parity_sector = raid5_compute_sector(conf, r_sector_first + i,
>> + 0, &disk, &sh);
>> + BUG_ON(sh.pd_idx != le32_to_cpu(e->parity_disk));
>> + parity_rdev = conf->disks[sh.pd_idx].rdev;
>> +
>> + BUG_ON(parity_rdev->bdev->bd_dev != log->rdev->bdev->bd_dev);
>> + pr_debug("%s:%*s write parity at sector %llu, disk %s\n",
>> + __func__, indent, "",
>> + (unsigned long long)parity_sector,
>> + bdevname(parity_rdev->bdev, b));
>> + if (!sync_page_io(parity_rdev, parity_sector, block_size,
>> + page1, REQ_OP_WRITE, 0, false)) {
>> + pr_debug("%s:%*s parity write error!\n", __func__,
>> + indent, "");
>> + md_error(mddev, parity_rdev);
>> + ret = -EIO;
>> + goto out;
>> + }
>> + }
>> +out:
>> + __free_pages(pages, 1);
>> + return ret;
>> +}
>> +
>> +static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr)
>> +{
>> + struct ppl_conf *ppl_conf = log->ppl_conf;
>> + struct md_rdev *rdev = log->rdev;
>> + struct mddev *mddev = rdev->mddev;
>> + sector_t ppl_sector = rdev->ppl.sector + (PPL_HEADER_SIZE >> 9);
>> + struct page *page;
>> + int i;
>> + int ret = 0;
>> +
>> + page = alloc_page(GFP_KERNEL);
>> + if (!page)
>> + return -ENOMEM;
>> +
>> + /* iterate through all PPL entries saved */
>> + for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++) {
>> + struct ppl_header_entry *e = &pplhdr->entries[i];
>> + u32 pp_size = le32_to_cpu(e->pp_size);
>> + sector_t sector = ppl_sector;
>> + int ppl_entry_sectors = pp_size >> 9;
>> + u32 crc, crc_stored;
>> +
>> + pr_debug("%s: disk: %d entry: %d ppl_sector: %llu pp_size: %u\n",
>> + __func__, rdev->raid_disk, i,
>> + (unsigned long long)ppl_sector, pp_size);
>> +
>> + crc = ~0;
>> + crc_stored = le32_to_cpu(e->checksum);
>> +
>> + /* read parial parity for this entry and calculate its checksum */
>> + while (pp_size) {
>> + int s = pp_size > PAGE_SIZE ? PAGE_SIZE : pp_size;
>> +
>> + if (!sync_page_io(rdev, sector - rdev->data_offset,
>> + s, page, REQ_OP_READ, 0, false)) {
>> + md_error(mddev, rdev);
>> + ret = -EIO;
>> + goto out;
>> + }
>> +
>> + crc = crc32c_le(crc, page_address(page), s);
>> +
>> + pp_size -= s;
>> + sector += s >> 9;
>> + }
>> +
>> + crc = ~crc;
>> +
>> + if (crc != crc_stored) {
>> + /*
>> + * Don't recover this entry if the checksum does not
>> + * match, but keep going and try to recover other
>> + * entries.
>> + */
>> + pr_debug("%s: ppl entry crc does not match: stored: 0x%x calculated: 0x%x\n",
>> + __func__, crc_stored, crc);
>> + ppl_conf->mismatch_count++;
>> + } else {
>> + ret = ppl_recover_entry(log, e, ppl_sector);
>> + if (ret)
>> + goto out;
>> + ppl_conf->recovered_entries++;
>> + }
>> +
>> + ppl_sector += ppl_entry_sectors;
>> + }
>> +out:
>> + __free_page(page);
>> + return ret;
>> +}
>> +
>> +static int ppl_write_empty_header(struct ppl_log *log)
>> +{
>> + struct page *page;
>> + struct ppl_header *pplhdr;
>> + struct md_rdev *rdev = log->rdev;
>> + int ret = 0;
>> +
>> + pr_debug("%s: disk: %d ppl_sector: %llu\n", __func__,
>> + rdev->raid_disk, (unsigned long long)rdev->ppl.sector);
>> +
>> + page = alloc_page(GFP_NOIO | __GFP_ZERO);
>> + if (!page)
>> + return -ENOMEM;
>> +
>> + pplhdr = page_address(page);
>> + memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
>> + pplhdr->signature = cpu_to_le32(log->ppl_conf->signature);
>> + pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));
>> +
>> + if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
>> + PPL_HEADER_SIZE, page, REQ_OP_WRITE, 0, false)) {
>
> write with FUA? otherwise, the empty header might not set down in the disks.
OK.
>> + md_error(rdev->mddev, rdev);
>> + ret = -EIO;
>> + }
>> +
>> + __free_page(page);
>> + return ret;
>> +}
>> +
>> +static int ppl_load_distributed(struct ppl_log *log)
>> +{
>> + struct ppl_conf *ppl_conf = log->ppl_conf;
>> + struct md_rdev *rdev = log->rdev;
>> + struct mddev *mddev = rdev->mddev;
>> + struct page *page;
>> + struct ppl_header *pplhdr;
>> + u32 crc, crc_stored;
>> + u32 signature;
>> + int ret = 0;
>> +
>> + pr_debug("%s: disk: %d\n", __func__, rdev->raid_disk);
>> +
>> + /* read PPL header */
>> + page = alloc_page(GFP_KERNEL);
>> + if (!page)
>> + return -ENOMEM;
>> +
>> + if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
>> + PAGE_SIZE, page, REQ_OP_READ, 0, false)) {
>> + md_error(mddev, rdev);
>> + ret = -EIO;
>> + goto out;
>> + }
>> + pplhdr = page_address(page);
>> +
>> + /* check header validity */
>> + crc_stored = le32_to_cpu(pplhdr->checksum);
>> + pplhdr->checksum = 0;
>> + crc = ~crc32c_le(~0, pplhdr, PAGE_SIZE);
>> +
>> + if (crc_stored != crc) {
>> + pr_debug("%s: ppl header crc does not match: stored: 0x%x calculated: 0x%x\n",
>> + __func__, crc_stored, crc);
>> + ppl_conf->mismatch_count++;
>> + goto out;
>> + }
>> +
>> + signature = le32_to_cpu(pplhdr->signature);
>> +
>> + if (mddev->external) {
>> + /*
>> + * For external metadata the header signature is set and
>> + * validated in userspace.
>> + */
>> + ppl_conf->signature = signature;
>> + } else if (ppl_conf->signature != signature) {
>> + pr_debug("%s: ppl header signature does not match: stored: 0x%x configured: 0x%x\n",
>> + __func__, signature, ppl_conf->signature);
>> + ppl_conf->mismatch_count++;
>> + goto out;
>> + }
>> +
>> + /* attempt to recover from log if we are starting a dirty array */
>> + if (!mddev->pers && mddev->recovery_cp != MaxSector)
>> + ret = ppl_recover(log, pplhdr);
>
> when could mddev->pers be null?
When the array is inactive - we are starting the array with ppl, not
enabling ppl at runtime.
> we need flush disk cache here. I know you assume disks don't enable cache yet,
> but it's simple to do a flush here.
You are right, I will add it.
Thanks,
Artur
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 6/7] raid5-ppl: support disk hot add/remove with PPL
2017-02-28 1:22 ` Shaohua Li
@ 2017-03-01 16:14 ` Artur Paszkiewicz
0 siblings, 0 replies; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-03-01 16:14 UTC (permalink / raw)
To: Shaohua Li; +Cc: shli, linux-raid
On 02/28/2017 02:22 AM, Shaohua Li wrote:
> On Tue, Feb 21, 2017 at 08:44:00PM +0100, Artur Paszkiewicz wrote:
>> Add a function to modify the log by removing an rdev when a drive fails
>> or adding when a spare/replacement is activated as a raid member.
>>
>> Removing a disk just clears the child log rdev pointer. No new stripes
>> will be accepted for this child log in ppl_write_stripe() and running io
>> units will be processed without writing PPL to the device.
>>
>> Adding a disk sets the child log rdev pointer and writes an empty PPL
>> header.
>>
>> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
>> ---
>> drivers/md/raid5-ppl.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
>> drivers/md/raid5.c | 15 +++++++++++++++
>> drivers/md/raid5.h | 8 ++++++++
>> 3 files changed, 70 insertions(+)
>>
>> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
>> index a7693353243a..c2070d124849 100644
>> --- a/drivers/md/raid5-ppl.c
>> +++ b/drivers/md/raid5-ppl.c
>> @@ -319,6 +319,12 @@ static void ppl_submit_iounit(struct ppl_io_unit *io)
>>
>> bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES, ppl_conf->bs);
>> bio->bi_private = io;
>> +
>> + if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
>> + ppl_log_endio(bio);
>> + return;
>> + }
>> +
>> bio->bi_end_io = ppl_log_endio;
>> bio->bi_opf = REQ_OP_WRITE | REQ_FUA;
>> bio->bi_bdev = log->rdev->bdev;
>> @@ -1098,3 +1104,44 @@ int ppl_init_log(struct r5conf *conf)
>> ppl_exit_log(ppl_conf);
>> return ret;
>> }
>> +
>> +int ppl_modify_log(struct ppl_conf *ppl_conf, struct md_rdev *rdev,
>> + enum ppl_modify_log_operation operation)
>> +{
>> + struct ppl_log *log;
>> + int ret = 0;
>> + char b[BDEVNAME_SIZE];
>> +
>> + if (!rdev)
>> + return -EINVAL;
>> +
>> + pr_debug("%s: disk: %d operation: %s dev: %s\n",
>> + __func__, rdev->raid_disk,
>> + operation == PPL_MODIFY_LOG_DISK_REMOVE ? "remove" :
>> + (operation == PPL_MODIFY_LOG_DISK_ADD ? "add" : "?"),
>> + bdevname(rdev->bdev, b));
>> +
>> + if (rdev->raid_disk < 0)
>> + return 0;
>> +
>> + if (rdev->raid_disk >= ppl_conf->count)
>> + return -ENODEV;
>> +
>> + log = &ppl_conf->child_logs[rdev->raid_disk];
>> +
>> + mutex_lock(&log->io_mutex);
>> + if (operation == PPL_MODIFY_LOG_DISK_REMOVE) {
>> + log->rdev = NULL;
>> + } else if (operation == PPL_MODIFY_LOG_DISK_ADD) {
>> + ret = ppl_validate_rdev(rdev);
>> + if (!ret) {
>> + log->rdev = rdev;
>> + ret = ppl_write_empty_header(log);
>> + }
>> + } else {
>> + ret = -EINVAL;
>> + }
>> + mutex_unlock(&log->io_mutex);
>> +
>> + return ret;
>> +}
>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
>> index 8b52392457d8..b17e90f06f19 100644
>> --- a/drivers/md/raid5.c
>> +++ b/drivers/md/raid5.c
>> @@ -7623,6 +7623,12 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
>> *rdevp = rdev;
>> }
>> }
>> + if (conf->ppl) {
>> + err = ppl_modify_log(conf->ppl, rdev,
>> + PPL_MODIFY_LOG_DISK_REMOVE);
>> + if (err)
>> + goto abort;
>> + }
>> if (p->replacement) {
>> /* We must have just cleared 'rdev' */
>> p->rdev = p->replacement;
>> @@ -7632,6 +7638,10 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
>> */
>> p->replacement = NULL;
>> clear_bit(WantReplacement, &rdev->flags);
>> +
>> + if (conf->ppl)
>> + err = ppl_modify_log(conf->ppl, p->rdev,
>> + PPL_MODIFY_LOG_DISK_ADD);
>> } else
>> /* We might have just removed the Replacement as faulty-
>> * clear the bit just in case
>> @@ -7695,6 +7705,11 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>> if (rdev->saved_raid_disk != disk)
>> conf->fullsync = 1;
>> rcu_assign_pointer(p->rdev, rdev);
>> +
>> + if (conf->ppl)
>> + err = ppl_modify_log(conf->ppl, rdev,
>> + PPL_MODIFY_LOG_DISK_ADD);
>> +
>> goto out;
>> }
>> }
>> diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
>> index f915a7a0e752..43cfa5fa71b3 100644
>> --- a/drivers/md/raid5.h
>> +++ b/drivers/md/raid5.h
>> @@ -806,4 +806,12 @@ extern void ppl_exit_log(struct ppl_conf *log);
>> extern int ppl_write_stripe(struct ppl_conf *log, struct stripe_head *sh);
>> extern void ppl_write_stripe_run(struct ppl_conf *log);
>> extern void ppl_stripe_write_finished(struct stripe_head *sh);
>> +
>> +enum ppl_modify_log_operation {
>> + PPL_MODIFY_LOG_DISK_REMOVE,
>> + PPL_MODIFY_LOG_DISK_ADD,
>> +};
>
> a bool for this parameter is better
>
>> +extern int ppl_modify_log(struct ppl_conf *log, struct md_rdev *rdev,
>> + enum ppl_modify_log_operation operation);
>
> So this should be put into raid5-log.h and rename to log_modify_log(conf, xxx)
> or other sensible name.
OK, I will do that.
Thanks,
Artur
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 7/7] raid5-ppl: runtime PPL enabling or disabling
2017-02-28 1:31 ` Shaohua Li
@ 2017-03-01 16:14 ` Artur Paszkiewicz
0 siblings, 0 replies; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-03-01 16:14 UTC (permalink / raw)
To: Shaohua Li; +Cc: shli, linux-raid
On 02/28/2017 02:31 AM, Shaohua Li wrote:
> On Tue, Feb 21, 2017 at 08:44:01PM +0100, Artur Paszkiewicz wrote:
>> Allow writing to 'consistency_policy' attribute when the array is
>> active. Add a new function 'change_consistency_policy' to the
>> md_personality operations structure to handle the change in the
>> personality code. Values "ppl" and "resync" are accepted and
>> turn PPL on and off respectively.
>>
>> When enabling PPL its location and size should first be set using
>> 'ppl_sector' and 'ppl_size' attributes and a valid PPL header should be
>> written at this location on each member device.
>>
>> Enabling or disabling PPL is performed under a suspended array. The
>> raid5_reset_stripe_cache function frees the stripe cache and allocates
>> it again in order to allocate or free the ppl_pages for the stripes in
>> the stripe cache.
>>
>> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
>> ---
>> drivers/md/md.c | 12 ++++++++---
>> drivers/md/md.h | 2 ++
>> drivers/md/raid5-ppl.c | 4 ++++
>> drivers/md/raid5.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++
>> 4 files changed, 73 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/md/md.c b/drivers/md/md.c
>> index 3ff979d538d4..b70e19513588 100644
>> --- a/drivers/md/md.c
>> +++ b/drivers/md/md.c
>> @@ -5003,14 +5003,20 @@ consistency_policy_show(struct mddev *mddev, char *page)
>> static ssize_t
>> consistency_policy_store(struct mddev *mddev, const char *buf, size_t len)
>> {
>> + int err = 0;
>> +
>> if (mddev->pers) {
>> - return -EBUSY;
>> + if (mddev->pers->change_consistency_policy)
>> + err = mddev->pers->change_consistency_policy(mddev, buf);
>> + else
>> + err = -EBUSY;
>> } else if (mddev->external && strncmp(buf, "ppl", 3) == 0) {
>> set_bit(MD_HAS_PPL, &mddev->flags);
>> - return len;
>> } else {
>> - return -EINVAL;
>> + err = -EINVAL;
>> }
>> +
>> + return err ? err : len;
>> }
>>
>> static struct md_sysfs_entry md_consistency_policy =
>> diff --git a/drivers/md/md.h b/drivers/md/md.h
>> index 66a5a16e79f7..88a5155c152e 100644
>> --- a/drivers/md/md.h
>> +++ b/drivers/md/md.h
>> @@ -548,6 +548,8 @@ struct md_personality
>> /* congested implements bdi.congested_fn().
>> * Will not be called while array is 'suspended' */
>> int (*congested)(struct mddev *mddev, int bits);
>> + /* Changes the consistency policy of an active array. */
>> + int (*change_consistency_policy)(struct mddev *mddev, const char *buf);
>> };
>>
>> struct md_sysfs_entry {
>> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
>> index c2070d124849..a5c4d3333bce 100644
>> --- a/drivers/md/raid5-ppl.c
>> +++ b/drivers/md/raid5-ppl.c
>> @@ -1095,6 +1095,10 @@ int ppl_init_log(struct r5conf *conf)
>> */
>> mddev->recovery_cp = MaxSector;
>> set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
>> + } else if (mddev->pers && ppl_conf->mismatch_count > 0) {
>> + /* no mismatch allowed when enabling PPL for a running array */
>> + ret = -EINVAL;
>> + goto err;
>> }
>>
>> conf->ppl = ppl_conf;
>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
>> index b17e90f06f19..754fb8e1c76f 100644
>> --- a/drivers/md/raid5.c
>> +++ b/drivers/md/raid5.c
>> @@ -8319,6 +8319,63 @@ static void *raid6_takeover(struct mddev *mddev)
>> return setup_conf(mddev);
>> }
>>
>> +static void raid5_reset_stripe_cache(struct mddev *mddev)
>> +{
>> + struct r5conf *conf = mddev->private;
>> +
>> + mutex_lock(&conf->cache_size_mutex);
>> + while (conf->max_nr_stripes &&
>> + drop_one_stripe(conf))
>> + ;
>> + while (conf->min_nr_stripes > conf->max_nr_stripes &&
>> + grow_one_stripe(conf, GFP_KERNEL))
>> + ;
>> + mutex_unlock(&conf->cache_size_mutex);
>> +}
>> +
>> +static int raid5_change_consistency_policy(struct mddev *mddev, const char *buf)
>> +{
>> + struct r5conf *conf;
>> + int err;
>> +
>> + err = mddev_lock(mddev);
>> + if (err)
>> + return err;
>> + conf = mddev->private;
>> + if (!conf) {
>> + mddev_unlock(mddev);
>> + return -ENODEV;
>> + }
>> +
>> + if (strncmp(buf, "ppl", 3) == 0 &&
>> + !test_bit(MD_HAS_PPL, &mddev->flags)) {
>> + mddev_suspend(mddev);
>> + err = ppl_init_log(conf);
>
> I didn't see you check if all rdev have valid ppl setting in ppl_load. Am I
> missing anything? Is it possible some rdevs have ppl set, but some not. In the
> case, we should just bail out.
All rdevs should have valid ppl settings, this is checked in
ppl_validate_rdev(), just before ppl_load() is called.
> Also check if this is raid5
pers->change_consistency_policy is only set for raid5_personality, so it
is (currently) not necessary.
Thanks,
Artur
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 3/7] raid5-ppl: Partial Parity Log write logging implementation
2017-03-01 16:13 ` Artur Paszkiewicz
@ 2017-03-01 17:51 ` Shaohua Li
0 siblings, 0 replies; 25+ messages in thread
From: Shaohua Li @ 2017-03-01 17:51 UTC (permalink / raw)
To: Artur Paszkiewicz; +Cc: shli, linux-raid
On Wed, Mar 01, 2017 at 05:13:38PM +0100, Artur Paszkiewicz wrote:
> On 02/28/2017 01:04 AM, Shaohua Li wrote:
> > On Tue, Feb 21, 2017 at 08:43:57PM +0100, Artur Paszkiewicz wrote:
> >> This implements the PPL write logging functionality. The description
> >> of PPL is added to the documentation. More details can be found in the
> >> comments in raid5-ppl.c.
> >>
> >> Put the PPL metadata structures to md_p.h because userspace tools
> >> (mdadm) will also need to read/write PPL.
> >>
> >> Warn about using PPL with enabled disk volatile write-back cache for
> >> now. It can be removed once disk cache flushing before writing PPL is
> >> implemented.
> >>
> >> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
> >> ---
> >> Documentation/md/raid5-ppl.txt | 44 +++
> >> drivers/md/Makefile | 2 +-
> >> drivers/md/raid5-ppl.c | 617 +++++++++++++++++++++++++++++++++++++++++
> >> drivers/md/raid5.c | 49 +++-
> >> drivers/md/raid5.h | 8 +
> >> include/uapi/linux/raid/md_p.h | 26 ++
> >> 6 files changed, 738 insertions(+), 8 deletions(-)
> >> create mode 100644 Documentation/md/raid5-ppl.txt
> >> create mode 100644 drivers/md/raid5-ppl.c
> >>
> >> diff --git a/Documentation/md/raid5-ppl.txt b/Documentation/md/raid5-ppl.txt
> >> new file mode 100644
> >> index 000000000000..127072b09363
> >> --- /dev/null
> >> +++ b/Documentation/md/raid5-ppl.txt
> >> @@ -0,0 +1,44 @@
> >> +Partial Parity Log
> >> +
> >> +
> >> + while (stripes_count--) {
> >> + /*
> >> + * if entry without partial parity just skip its stripes
> >> + * without adding pages to bio
> >> + */
> >> + if (pp_size > 0 &&
> >> + !bio_add_page(bio, sh->ppl_page, PAGE_SIZE, 0)) {
> >> + struct bio *prev = bio;
> >> +
> >> + bio = bio_alloc_bioset(GFP_NOIO, BIO_MAX_PAGES,
> >> + ppl_conf->bs);
> >
> > The code keeps allocating bios but doesn't dispatch any yet. The bioset can't
> > guarantee the allocation successes. To have the guarantee, we must make sure
> > previous bios could finish.
>
> Is it ok to submit the bio before allocating another from the same
> bioset, without waiting for it to complete? The description for
> bio_alloc_bioset() suggests this, if I understand it correctly: "Callers
> that need to allocate more than 1 bio must always submit the previously
> allocated bio for IO before attempting to allocate a new one."
Yes, I mean submit.
> >> return -EINVAL;
> >> if (mddev->delta_disks == 0 &&
> >> mddev->new_layout == mddev->layout &&
> >> diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
> >> index 3cc4cb28f7e6..f915a7a0e752 100644
> >> --- a/drivers/md/raid5.h
> >> +++ b/drivers/md/raid5.h
> >> @@ -230,6 +230,7 @@ struct stripe_head {
> >> struct list_head r5c; /* for r5c_cache->stripe_in_journal */
> >>
> >> struct page *ppl_page; /* partial parity of this stripe */
> >> + struct ppl_io_unit *ppl_log_io;
> >
> > Maybe we should put the ppl fields and raid5 fields to a union
>
> Good idea, will do.
>
> >> /**
> >> * struct stripe_operations
> >> * @target - STRIPE_OP_COMPUTE_BLK target
> >> @@ -689,6 +690,7 @@ struct r5conf {
> >> int group_cnt;
> >> int worker_cnt_per_group;
> >> struct r5l_log *log;
> >> + struct ppl_conf *ppl;
> >
> > Maybe use void * log_private, so works for both raid5-cache and ppl
>
> Do you mean replace "struct ppl_conf *ppl" with "void *log_private"?
Right. But if this makes checking the log type hard, ignore it.
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 5/7] raid5-ppl: load and recover the log
2017-03-01 16:14 ` Artur Paszkiewicz
@ 2017-03-01 17:59 ` Shaohua Li
2017-03-02 8:40 ` Artur Paszkiewicz
0 siblings, 1 reply; 25+ messages in thread
From: Shaohua Li @ 2017-03-01 17:59 UTC (permalink / raw)
To: Artur Paszkiewicz; +Cc: shli, linux-raid
On Wed, Mar 01, 2017 at 05:14:18PM +0100, Artur Paszkiewicz wrote:
> On 02/28/2017 02:12 AM, Shaohua Li wrote:
> > On Tue, Feb 21, 2017 at 08:43:59PM +0100, Artur Paszkiewicz wrote:
> >> Load the log from each disk when starting the array and recover if the
> >> array is dirty.
> >>
> >> The initial empty PPL is written by mdadm. When loading the log we
> >> verify the header checksum and signature. For external metadata arrays
> >> the signature is verified in userspace, so here we read it from the
> >> header, verifying only if it matches on all disks, and use it later when
> >> writing PPL.
> >>
> >> In addition to the header checksum, each header entry also contains a
> >> checksum of its partial parity data. If the header is valid, recovery is
> >> performed for each entry until an invalid entry is found. If the array
> >> is not degraded and recovery using PPL fully succeeds, there is no need
> >> to resync the array because data and parity will be consistent, so in
> >> this case resync will be disabled.
> >>
> >> Due to compatibility with IMSM implementations on other systems, we
> >> can't assume that the recovery data block size is always 4K. Writes
> >> generated by MD raid5 don't have this issue, but when recovering PPL
> >> written in other environments it is possible to have entries with
> >> 512-byte sector granularity. The recovery code takes this into account
> >> and also the logical sector size of the underlying drives.
> >>
> >> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
> >> ---
> >> drivers/md/raid5-ppl.c | 483 +++++++++++++++++++++++++++++++++++++++++++++++++
> >> drivers/md/raid5.c | 5 +-
> >> 2 files changed, 487 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
> >> index a00cabf1adf6..a7693353243a 100644
> >> --- a/drivers/md/raid5-ppl.c
> >> +++ b/drivers/md/raid5-ppl.c
> >> @@ -16,6 +16,7 @@
> >> #include <linux/blkdev.h>
> >> #include <linux/slab.h>
> >> #include <linux/crc32c.h>
> >> +#include <linux/async_tx.h>
> >> #include <linux/raid/md_p.h>
> >> #include "md.h"
> >> #include "raid5.h"
> >> @@ -84,6 +85,10 @@ struct ppl_conf {
> >> mempool_t *io_pool;
> >> struct bio_set *bs;
> >> mempool_t *meta_pool;
> >> +
> >> + /* used only for recovery */
> >> + int recovered_entries;
> >> + int mismatch_count;
> >> };
> >>
> >> struct ppl_log {
> >> @@ -450,6 +455,467 @@ void ppl_stripe_write_finished(struct stripe_head *sh)
> >> ppl_io_unit_finished(io);
> >> }
> >>
> >> +static void ppl_xor(int size, struct page *page1, struct page *page2,
> >> + struct page *page_result)
> >> +{
> >> + struct async_submit_ctl submit;
> >> + struct dma_async_tx_descriptor *tx;
> >> + struct page *xor_srcs[] = { page1, page2 };
> >> +
> >> + init_async_submit(&submit, ASYNC_TX_ACK|ASYNC_TX_XOR_DROP_DST,
> >> + NULL, NULL, NULL, NULL);
> >> + tx = async_xor(page_result, xor_srcs, 0, 2, size, &submit);
> >> +
> >> + async_tx_quiesce(&tx);
> >> +}
> >> +
> >> +/*
> >> + * PPL recovery strategy: xor partial parity and data from all modified data
> >> + * disks within a stripe and write the result as the new stripe parity. If all
> >> + * stripe data disks are modified (full stripe write), no partial parity is
> >> + * available, so just xor the data disks.
> >> + *
> >> + * Recovery of a PPL entry shall occur only if all modified data disks are
> >> + * available and read from all of them succeeds.
> >> + *
> >> + * A PPL entry applies to a stripe, partial parity size for an entry is at most
> >> + * the size of the chunk. Examples of possible cases for a single entry:
> >> + *
> >> + * case 0: single data disk write:
> >> + * data0 data1 data2 ppl parity
> >> + * +--------+--------+--------+ +--------------------+
> >> + * | ------ | ------ | ------ | +----+ | (no change) |
> >> + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
> >> + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
> >> + * | ------ | ------ | ------ | +----+ | (no change) |
> >> + * +--------+--------+--------+ +--------------------+
> >> + * pp_size = data_size
> >> + *
> >> + * case 1: more than one data disk write:
> >> + * data0 data1 data2 ppl parity
> >> + * +--------+--------+--------+ +--------------------+
> >> + * | ------ | ------ | ------ | +----+ | (no change) |
> >> + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
> >> + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
> >> + * | ------ | ------ | ------ | +----+ | (no change) |
> >> + * +--------+--------+--------+ +--------------------+
> >> + * pp_size = data_size / modified_data_disks
> >> + *
> >> + * case 2: write to all data disks (also full stripe write):
> >> + * data0 data1 data2 parity
> >> + * +--------+--------+--------+ +--------------------+
> >> + * | ------ | ------ | ------ | | (no change) |
> >> + * | -data- | -data- | -data- | --------> | xor all data |
> >> + * | ------ | ------ | ------ | --------> | (no change) |
> >> + * | ------ | ------ | ------ | | (no change) |
> >> + * +--------+--------+--------+ +--------------------+
> >> + * pp_size = 0
> >> + *
> >> + * The following cases are possible only in other implementations. The recovery
> >> + * code can handle them, but they are not generated at runtime because they can
> >> + * be reduced to cases 0, 1 and 2:
> >> + *
> >> + * case 3:
> >> + * data0 data1 data2 ppl parity
> >> + * +--------+--------+--------+ +----+ +--------------------+
> >> + * | ------ | -data- | -data- | | pp | | data1 ^ data2 ^ pp |
> >> + * | ------ | -data- | -data- | | pp | -> | data1 ^ data2 ^ pp |
> >> + * | -data- | -data- | -data- | | -- | -> | xor all data |
> >> + * | -data- | -data- | ------ | | pp | | data0 ^ data1 ^ pp |
> >> + * +--------+--------+--------+ +----+ +--------------------+
> >> + * pp_size = chunk_size
> >> + *
> >> + * case 4:
> >> + * data0 data1 data2 ppl parity
> >> + * +--------+--------+--------+ +----+ +--------------------+
> >> + * | ------ | -data- | ------ | | pp | | data1 ^ pp |
> >> + * | ------ | ------ | ------ | | -- | -> | (no change) |
> >> + * | ------ | ------ | ------ | | -- | -> | (no change) |
> >> + * | -data- | ------ | ------ | | pp | | data0 ^ pp |
> >> + * +--------+--------+--------+ +----+ +--------------------+
> >> + * pp_size = chunk_size
> >> + */
> >> +static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
> >> + sector_t ppl_sector)
> >> +{
> >> + struct ppl_conf *ppl_conf = log->ppl_conf;
> >> + struct mddev *mddev = ppl_conf->mddev;
> >> + struct r5conf *conf = mddev->private;
> >> + int block_size = ppl_conf->block_size;
> >> + struct page *pages;
> >> + struct page *page1;
> >> + struct page *page2;
> >> + sector_t r_sector_first;
> >> + sector_t r_sector_last;
> >> + int strip_sectors;
> >> + int data_disks;
> >> + int i;
> >> + int ret = 0;
> >> + char b[BDEVNAME_SIZE];
> >> + unsigned int pp_size = le32_to_cpu(e->pp_size);
> >> + unsigned int data_size = le32_to_cpu(e->data_size);
> >> +
> >> + r_sector_first = le64_to_cpu(e->data_sector) * (block_size >> 9);
> >> +
> >> + if ((pp_size >> 9) < conf->chunk_sectors) {
> >> + if (pp_size > 0) {
> >> + data_disks = data_size / pp_size;
> >> + strip_sectors = pp_size >> 9;
> >> + } else {
> >> + data_disks = conf->raid_disks - conf->max_degraded;
> >> + strip_sectors = (data_size >> 9) / data_disks;
> >> + }
> >> + r_sector_last = r_sector_first +
> >> + (data_disks - 1) * conf->chunk_sectors +
> >> + strip_sectors;
> >> + } else {
> >> + data_disks = conf->raid_disks - conf->max_degraded;
> >> + strip_sectors = conf->chunk_sectors;
> >> + r_sector_last = r_sector_first + (data_size >> 9);
> >> + }
> >> +
> >> + pages = alloc_pages(GFP_KERNEL, 1);
> >
> > order != 0 allocation should be avoid if possible. Here sounds not necessary
>
> OK, I will allocate and free them separately.
>
> >> + if (!pages)
> >> + return -ENOMEM;
> >> + page1 = pages;
> >> + page2 = pages + 1;
> >> +
> >> + pr_debug("%s: array sector first: %llu last: %llu\n", __func__,
> >> + (unsigned long long)r_sector_first,
> >> + (unsigned long long)r_sector_last);
> >> +
> >> + /* if start and end is 4k aligned, use a 4k block */
> >> + if (block_size == 512 &&
> >> + (r_sector_first & (STRIPE_SECTORS - 1)) == 0 &&
> >> + (r_sector_last & (STRIPE_SECTORS - 1)) == 0)
> >> + block_size = STRIPE_SIZE;
> >> +
> >> + /* iterate through blocks in strip */
> >> + for (i = 0; i < strip_sectors; i += (block_size >> 9)) {
> >> + bool update_parity = false;
> >> + sector_t parity_sector;
> >> + struct md_rdev *parity_rdev;
> >> + struct stripe_head sh;
> >> + int disk;
> >> + int indent = 0;
> >> +
> >> + pr_debug("%s:%*s iter %d start\n", __func__, indent, "", i);
> >> + indent += 2;
> >> +
> >> + memset(page_address(page1), 0, PAGE_SIZE);
> >> +
> >> + /* iterate through data member disks */
> >> + for (disk = 0; disk < data_disks; disk++) {
> >> + int dd_idx;
> >> + struct md_rdev *rdev;
> >> + sector_t sector;
> >> + sector_t r_sector = r_sector_first + i +
> >> + (disk * conf->chunk_sectors);
> >> +
> >> + pr_debug("%s:%*s data member disk %d start\n",
> >> + __func__, indent, "", disk);
> >> + indent += 2;
> >> +
> >> + if (r_sector >= r_sector_last) {
> >> + pr_debug("%s:%*s array sector %llu doesn't need parity update\n",
> >> + __func__, indent, "",
> >> + (unsigned long long)r_sector);
> >> + indent -= 2;
> >> + continue;
> >> + }
> >> +
> >> + update_parity = true;
> >> +
> >> + /* map raid sector to member disk */
> >> + sector = raid5_compute_sector(conf, r_sector, 0,
> >> + &dd_idx, NULL);
> >> + pr_debug("%s:%*s processing array sector %llu => data member disk %d, sector %llu\n",
> >> + __func__, indent, "",
> >> + (unsigned long long)r_sector, dd_idx,
> >> + (unsigned long long)sector);
> >> +
> >> + rdev = conf->disks[dd_idx].rdev;
> >> + if (!rdev) {
> >> + pr_debug("%s:%*s data member disk %d missing\n",
> >> + __func__, indent, "", dd_idx);
> >> + update_parity = false;
> >> + break;
> >> + }
> >> +
> >> + pr_debug("%s:%*s reading data member disk %s sector %llu\n",
> >> + __func__, indent, "", bdevname(rdev->bdev, b),
> >> + (unsigned long long)sector);
> >> + if (!sync_page_io(rdev, sector, block_size, page2,
> >> + REQ_OP_READ, 0, false)) {
> >> + md_error(mddev, rdev);
> >> + pr_debug("%s:%*s read failed!\n", __func__,
> >> + indent, "");
> >> + ret = -EIO;
> >> + goto out;
> >> + }
> >> +
> >> + ppl_xor(block_size, page1, page2, page1);
> >> +
> >> + indent -= 2;
> >> + }
> >> +
> >> + if (!update_parity)
> >> + continue;
> >> +
> >> + if (pp_size > 0) {
> >> + pr_debug("%s:%*s reading pp disk sector %llu\n",
> >> + __func__, indent, "",
> >> + (unsigned long long)(ppl_sector + i));
> >> + if (!sync_page_io(log->rdev,
> >> + ppl_sector - log->rdev->data_offset + i,
> >> + block_size, page2, REQ_OP_READ, 0,
> >> + false)) {
> >> + pr_debug("%s:%*s read failed!\n", __func__,
> >> + indent, "");
> >> + md_error(mddev, log->rdev);
> >> + ret = -EIO;
> >> + goto out;
> >> + }
> >> +
> >> + ppl_xor(block_size, page1, page2, page1);
> >> + }
> >> +
> >> + /* map raid sector to parity disk */
> >> + parity_sector = raid5_compute_sector(conf, r_sector_first + i,
> >> + 0, &disk, &sh);
> >> + BUG_ON(sh.pd_idx != le32_to_cpu(e->parity_disk));
> >> + parity_rdev = conf->disks[sh.pd_idx].rdev;
> >> +
> >> + BUG_ON(parity_rdev->bdev->bd_dev != log->rdev->bdev->bd_dev);
> >> + pr_debug("%s:%*s write parity at sector %llu, disk %s\n",
> >> + __func__, indent, "",
> >> + (unsigned long long)parity_sector,
> >> + bdevname(parity_rdev->bdev, b));
> >> + if (!sync_page_io(parity_rdev, parity_sector, block_size,
> >> + page1, REQ_OP_WRITE, 0, false)) {
> >> + pr_debug("%s:%*s parity write error!\n", __func__,
> >> + indent, "");
> >> + md_error(mddev, parity_rdev);
> >> + ret = -EIO;
> >> + goto out;
> >> + }
> >> + }
> >> +out:
> >> + __free_pages(pages, 1);
> >> + return ret;
> >> +}
> >> +
> >> +static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr)
> >> +{
> >> + struct ppl_conf *ppl_conf = log->ppl_conf;
> >> + struct md_rdev *rdev = log->rdev;
> >> + struct mddev *mddev = rdev->mddev;
> >> + sector_t ppl_sector = rdev->ppl.sector + (PPL_HEADER_SIZE >> 9);
> >> + struct page *page;
> >> + int i;
> >> + int ret = 0;
> >> +
> >> + page = alloc_page(GFP_KERNEL);
> >> + if (!page)
> >> + return -ENOMEM;
> >> +
> >> + /* iterate through all PPL entries saved */
> >> + for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++) {
> >> + struct ppl_header_entry *e = &pplhdr->entries[i];
> >> + u32 pp_size = le32_to_cpu(e->pp_size);
> >> + sector_t sector = ppl_sector;
> >> + int ppl_entry_sectors = pp_size >> 9;
> >> + u32 crc, crc_stored;
> >> +
> >> + pr_debug("%s: disk: %d entry: %d ppl_sector: %llu pp_size: %u\n",
> >> + __func__, rdev->raid_disk, i,
> >> + (unsigned long long)ppl_sector, pp_size);
> >> +
> >> + crc = ~0;
> >> + crc_stored = le32_to_cpu(e->checksum);
> >> +
> >> + /* read parial parity for this entry and calculate its checksum */
> >> + while (pp_size) {
> >> + int s = pp_size > PAGE_SIZE ? PAGE_SIZE : pp_size;
> >> +
> >> + if (!sync_page_io(rdev, sector - rdev->data_offset,
> >> + s, page, REQ_OP_READ, 0, false)) {
> >> + md_error(mddev, rdev);
> >> + ret = -EIO;
> >> + goto out;
> >> + }
> >> +
> >> + crc = crc32c_le(crc, page_address(page), s);
> >> +
> >> + pp_size -= s;
> >> + sector += s >> 9;
> >> + }
> >> +
> >> + crc = ~crc;
> >> +
> >> + if (crc != crc_stored) {
> >> + /*
> >> + * Don't recover this entry if the checksum does not
> >> + * match, but keep going and try to recover other
> >> + * entries.
> >> + */
> >> + pr_debug("%s: ppl entry crc does not match: stored: 0x%x calculated: 0x%x\n",
> >> + __func__, crc_stored, crc);
> >> + ppl_conf->mismatch_count++;
> >> + } else {
> >> + ret = ppl_recover_entry(log, e, ppl_sector);
> >> + if (ret)
> >> + goto out;
> >> + ppl_conf->recovered_entries++;
> >> + }
> >> +
> >> + ppl_sector += ppl_entry_sectors;
> >> + }
> >> +out:
> >> + __free_page(page);
> >> + return ret;
> >> +}
> >> +
> >> +static int ppl_write_empty_header(struct ppl_log *log)
> >> +{
> >> + struct page *page;
> >> + struct ppl_header *pplhdr;
> >> + struct md_rdev *rdev = log->rdev;
> >> + int ret = 0;
> >> +
> >> + pr_debug("%s: disk: %d ppl_sector: %llu\n", __func__,
> >> + rdev->raid_disk, (unsigned long long)rdev->ppl.sector);
> >> +
> >> + page = alloc_page(GFP_NOIO | __GFP_ZERO);
> >> + if (!page)
> >> + return -ENOMEM;
> >> +
> >> + pplhdr = page_address(page);
> >> + memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
> >> + pplhdr->signature = cpu_to_le32(log->ppl_conf->signature);
> >> + pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));
> >> +
> >> + if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
> >> + PPL_HEADER_SIZE, page, REQ_OP_WRITE, 0, false)) {
> >
> > write with FUA? otherwise, the empty header might not set down in the disks.
>
> OK.
>
> >> + md_error(rdev->mddev, rdev);
> >> + ret = -EIO;
> >> + }
> >> +
> >> + __free_page(page);
> >> + return ret;
> >> +}
> >> +
> >> +static int ppl_load_distributed(struct ppl_log *log)
> >> +{
> >> + struct ppl_conf *ppl_conf = log->ppl_conf;
> >> + struct md_rdev *rdev = log->rdev;
> >> + struct mddev *mddev = rdev->mddev;
> >> + struct page *page;
> >> + struct ppl_header *pplhdr;
> >> + u32 crc, crc_stored;
> >> + u32 signature;
> >> + int ret = 0;
> >> +
> >> + pr_debug("%s: disk: %d\n", __func__, rdev->raid_disk);
> >> +
> >> + /* read PPL header */
> >> + page = alloc_page(GFP_KERNEL);
> >> + if (!page)
> >> + return -ENOMEM;
> >> +
> >> + if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
> >> + PAGE_SIZE, page, REQ_OP_READ, 0, false)) {
> >> + md_error(mddev, rdev);
> >> + ret = -EIO;
> >> + goto out;
> >> + }
> >> + pplhdr = page_address(page);
> >> +
> >> + /* check header validity */
> >> + crc_stored = le32_to_cpu(pplhdr->checksum);
> >> + pplhdr->checksum = 0;
> >> + crc = ~crc32c_le(~0, pplhdr, PAGE_SIZE);
> >> +
> >> + if (crc_stored != crc) {
> >> + pr_debug("%s: ppl header crc does not match: stored: 0x%x calculated: 0x%x\n",
> >> + __func__, crc_stored, crc);
> >> + ppl_conf->mismatch_count++;
> >> + goto out;
> >> + }
> >> +
> >> + signature = le32_to_cpu(pplhdr->signature);
> >> +
> >> + if (mddev->external) {
> >> + /*
> >> + * For external metadata the header signature is set and
> >> + * validated in userspace.
> >> + */
> >> + ppl_conf->signature = signature;
> >> + } else if (ppl_conf->signature != signature) {
> >> + pr_debug("%s: ppl header signature does not match: stored: 0x%x configured: 0x%x\n",
> >> + __func__, signature, ppl_conf->signature);
> >> + ppl_conf->mismatch_count++;
> >> + goto out;
> >> + }
> >> +
> >> + /* attempt to recover from log if we are starting a dirty array */
> >> + if (!mddev->pers && mddev->recovery_cp != MaxSector)
> >> + ret = ppl_recover(log, pplhdr);
> >
> > when could mddev->pers be null?
>
> When the array is inactive - we are starting the array with ppl, not
> enabling ppl at runtime.
Didn't follow this. Can explain more?
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v4 5/7] raid5-ppl: load and recover the log
2017-03-01 17:59 ` Shaohua Li
@ 2017-03-02 8:40 ` Artur Paszkiewicz
0 siblings, 0 replies; 25+ messages in thread
From: Artur Paszkiewicz @ 2017-03-02 8:40 UTC (permalink / raw)
To: Shaohua Li; +Cc: shli, linux-raid
On 03/01/2017 06:59 PM, Shaohua Li wrote:
> On Wed, Mar 01, 2017 at 05:14:18PM +0100, Artur Paszkiewicz wrote:
>> On 02/28/2017 02:12 AM, Shaohua Li wrote:
>>> On Tue, Feb 21, 2017 at 08:43:59PM +0100, Artur Paszkiewicz wrote:
>>>> Load the log from each disk when starting the array and recover if the
>>>> array is dirty.
>>>>
>>>> The initial empty PPL is written by mdadm. When loading the log we
>>>> verify the header checksum and signature. For external metadata arrays
>>>> the signature is verified in userspace, so here we read it from the
>>>> header, verifying only if it matches on all disks, and use it later when
>>>> writing PPL.
>>>>
>>>> In addition to the header checksum, each header entry also contains a
>>>> checksum of its partial parity data. If the header is valid, recovery is
>>>> performed for each entry until an invalid entry is found. If the array
>>>> is not degraded and recovery using PPL fully succeeds, there is no need
>>>> to resync the array because data and parity will be consistent, so in
>>>> this case resync will be disabled.
>>>>
>>>> Due to compatibility with IMSM implementations on other systems, we
>>>> can't assume that the recovery data block size is always 4K. Writes
>>>> generated by MD raid5 don't have this issue, but when recovering PPL
>>>> written in other environments it is possible to have entries with
>>>> 512-byte sector granularity. The recovery code takes this into account
>>>> and also the logical sector size of the underlying drives.
>>>>
>>>> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
>>>> ---
>>>> drivers/md/raid5-ppl.c | 483 +++++++++++++++++++++++++++++++++++++++++++++++++
>>>> drivers/md/raid5.c | 5 +-
>>>> 2 files changed, 487 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
>>>> index a00cabf1adf6..a7693353243a 100644
>>>> --- a/drivers/md/raid5-ppl.c
>>>> +++ b/drivers/md/raid5-ppl.c
>>>> @@ -16,6 +16,7 @@
>>>> #include <linux/blkdev.h>
>>>> #include <linux/slab.h>
>>>> #include <linux/crc32c.h>
>>>> +#include <linux/async_tx.h>
>>>> #include <linux/raid/md_p.h>
>>>> #include "md.h"
>>>> #include "raid5.h"
>>>> @@ -84,6 +85,10 @@ struct ppl_conf {
>>>> mempool_t *io_pool;
>>>> struct bio_set *bs;
>>>> mempool_t *meta_pool;
>>>> +
>>>> + /* used only for recovery */
>>>> + int recovered_entries;
>>>> + int mismatch_count;
>>>> };
>>>>
>>>> struct ppl_log {
>>>> @@ -450,6 +455,467 @@ void ppl_stripe_write_finished(struct stripe_head *sh)
>>>> ppl_io_unit_finished(io);
>>>> }
>>>>
>>>> +static void ppl_xor(int size, struct page *page1, struct page *page2,
>>>> + struct page *page_result)
>>>> +{
>>>> + struct async_submit_ctl submit;
>>>> + struct dma_async_tx_descriptor *tx;
>>>> + struct page *xor_srcs[] = { page1, page2 };
>>>> +
>>>> + init_async_submit(&submit, ASYNC_TX_ACK|ASYNC_TX_XOR_DROP_DST,
>>>> + NULL, NULL, NULL, NULL);
>>>> + tx = async_xor(page_result, xor_srcs, 0, 2, size, &submit);
>>>> +
>>>> + async_tx_quiesce(&tx);
>>>> +}
>>>> +
>>>> +/*
>>>> + * PPL recovery strategy: xor partial parity and data from all modified data
>>>> + * disks within a stripe and write the result as the new stripe parity. If all
>>>> + * stripe data disks are modified (full stripe write), no partial parity is
>>>> + * available, so just xor the data disks.
>>>> + *
>>>> + * Recovery of a PPL entry shall occur only if all modified data disks are
>>>> + * available and read from all of them succeeds.
>>>> + *
>>>> + * A PPL entry applies to a stripe, partial parity size for an entry is at most
>>>> + * the size of the chunk. Examples of possible cases for a single entry:
>>>> + *
>>>> + * case 0: single data disk write:
>>>> + * data0 data1 data2 ppl parity
>>>> + * +--------+--------+--------+ +--------------------+
>>>> + * | ------ | ------ | ------ | +----+ | (no change) |
>>>> + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
>>>> + * | ------ | -data- | ------ | | pp | -> | data1 ^ pp |
>>>> + * | ------ | ------ | ------ | +----+ | (no change) |
>>>> + * +--------+--------+--------+ +--------------------+
>>>> + * pp_size = data_size
>>>> + *
>>>> + * case 1: more than one data disk write:
>>>> + * data0 data1 data2 ppl parity
>>>> + * +--------+--------+--------+ +--------------------+
>>>> + * | ------ | ------ | ------ | +----+ | (no change) |
>>>> + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
>>>> + * | -data- | -data- | ------ | | pp | -> | data0 ^ data1 ^ pp |
>>>> + * | ------ | ------ | ------ | +----+ | (no change) |
>>>> + * +--------+--------+--------+ +--------------------+
>>>> + * pp_size = data_size / modified_data_disks
>>>> + *
>>>> + * case 2: write to all data disks (also full stripe write):
>>>> + * data0 data1 data2 parity
>>>> + * +--------+--------+--------+ +--------------------+
>>>> + * | ------ | ------ | ------ | | (no change) |
>>>> + * | -data- | -data- | -data- | --------> | xor all data |
>>>> + * | ------ | ------ | ------ | --------> | (no change) |
>>>> + * | ------ | ------ | ------ | | (no change) |
>>>> + * +--------+--------+--------+ +--------------------+
>>>> + * pp_size = 0
>>>> + *
>>>> + * The following cases are possible only in other implementations. The recovery
>>>> + * code can handle them, but they are not generated at runtime because they can
>>>> + * be reduced to cases 0, 1 and 2:
>>>> + *
>>>> + * case 3:
>>>> + * data0 data1 data2 ppl parity
>>>> + * +--------+--------+--------+ +----+ +--------------------+
>>>> + * | ------ | -data- | -data- | | pp | | data1 ^ data2 ^ pp |
>>>> + * | ------ | -data- | -data- | | pp | -> | data1 ^ data2 ^ pp |
>>>> + * | -data- | -data- | -data- | | -- | -> | xor all data |
>>>> + * | -data- | -data- | ------ | | pp | | data0 ^ data1 ^ pp |
>>>> + * +--------+--------+--------+ +----+ +--------------------+
>>>> + * pp_size = chunk_size
>>>> + *
>>>> + * case 4:
>>>> + * data0 data1 data2 ppl parity
>>>> + * +--------+--------+--------+ +----+ +--------------------+
>>>> + * | ------ | -data- | ------ | | pp | | data1 ^ pp |
>>>> + * | ------ | ------ | ------ | | -- | -> | (no change) |
>>>> + * | ------ | ------ | ------ | | -- | -> | (no change) |
>>>> + * | -data- | ------ | ------ | | pp | | data0 ^ pp |
>>>> + * +--------+--------+--------+ +----+ +--------------------+
>>>> + * pp_size = chunk_size
>>>> + */
>>>> +static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e,
>>>> + sector_t ppl_sector)
>>>> +{
>>>> + struct ppl_conf *ppl_conf = log->ppl_conf;
>>>> + struct mddev *mddev = ppl_conf->mddev;
>>>> + struct r5conf *conf = mddev->private;
>>>> + int block_size = ppl_conf->block_size;
>>>> + struct page *pages;
>>>> + struct page *page1;
>>>> + struct page *page2;
>>>> + sector_t r_sector_first;
>>>> + sector_t r_sector_last;
>>>> + int strip_sectors;
>>>> + int data_disks;
>>>> + int i;
>>>> + int ret = 0;
>>>> + char b[BDEVNAME_SIZE];
>>>> + unsigned int pp_size = le32_to_cpu(e->pp_size);
>>>> + unsigned int data_size = le32_to_cpu(e->data_size);
>>>> +
>>>> + r_sector_first = le64_to_cpu(e->data_sector) * (block_size >> 9);
>>>> +
>>>> + if ((pp_size >> 9) < conf->chunk_sectors) {
>>>> + if (pp_size > 0) {
>>>> + data_disks = data_size / pp_size;
>>>> + strip_sectors = pp_size >> 9;
>>>> + } else {
>>>> + data_disks = conf->raid_disks - conf->max_degraded;
>>>> + strip_sectors = (data_size >> 9) / data_disks;
>>>> + }
>>>> + r_sector_last = r_sector_first +
>>>> + (data_disks - 1) * conf->chunk_sectors +
>>>> + strip_sectors;
>>>> + } else {
>>>> + data_disks = conf->raid_disks - conf->max_degraded;
>>>> + strip_sectors = conf->chunk_sectors;
>>>> + r_sector_last = r_sector_first + (data_size >> 9);
>>>> + }
>>>> +
>>>> + pages = alloc_pages(GFP_KERNEL, 1);
>>>
>>> order != 0 allocation should be avoid if possible. Here sounds not necessary
>>
>> OK, I will allocate and free them separately.
>>
>>>> + if (!pages)
>>>> + return -ENOMEM;
>>>> + page1 = pages;
>>>> + page2 = pages + 1;
>>>> +
>>>> + pr_debug("%s: array sector first: %llu last: %llu\n", __func__,
>>>> + (unsigned long long)r_sector_first,
>>>> + (unsigned long long)r_sector_last);
>>>> +
>>>> + /* if start and end is 4k aligned, use a 4k block */
>>>> + if (block_size == 512 &&
>>>> + (r_sector_first & (STRIPE_SECTORS - 1)) == 0 &&
>>>> + (r_sector_last & (STRIPE_SECTORS - 1)) == 0)
>>>> + block_size = STRIPE_SIZE;
>>>> +
>>>> + /* iterate through blocks in strip */
>>>> + for (i = 0; i < strip_sectors; i += (block_size >> 9)) {
>>>> + bool update_parity = false;
>>>> + sector_t parity_sector;
>>>> + struct md_rdev *parity_rdev;
>>>> + struct stripe_head sh;
>>>> + int disk;
>>>> + int indent = 0;
>>>> +
>>>> + pr_debug("%s:%*s iter %d start\n", __func__, indent, "", i);
>>>> + indent += 2;
>>>> +
>>>> + memset(page_address(page1), 0, PAGE_SIZE);
>>>> +
>>>> + /* iterate through data member disks */
>>>> + for (disk = 0; disk < data_disks; disk++) {
>>>> + int dd_idx;
>>>> + struct md_rdev *rdev;
>>>> + sector_t sector;
>>>> + sector_t r_sector = r_sector_first + i +
>>>> + (disk * conf->chunk_sectors);
>>>> +
>>>> + pr_debug("%s:%*s data member disk %d start\n",
>>>> + __func__, indent, "", disk);
>>>> + indent += 2;
>>>> +
>>>> + if (r_sector >= r_sector_last) {
>>>> + pr_debug("%s:%*s array sector %llu doesn't need parity update\n",
>>>> + __func__, indent, "",
>>>> + (unsigned long long)r_sector);
>>>> + indent -= 2;
>>>> + continue;
>>>> + }
>>>> +
>>>> + update_parity = true;
>>>> +
>>>> + /* map raid sector to member disk */
>>>> + sector = raid5_compute_sector(conf, r_sector, 0,
>>>> + &dd_idx, NULL);
>>>> + pr_debug("%s:%*s processing array sector %llu => data member disk %d, sector %llu\n",
>>>> + __func__, indent, "",
>>>> + (unsigned long long)r_sector, dd_idx,
>>>> + (unsigned long long)sector);
>>>> +
>>>> + rdev = conf->disks[dd_idx].rdev;
>>>> + if (!rdev) {
>>>> + pr_debug("%s:%*s data member disk %d missing\n",
>>>> + __func__, indent, "", dd_idx);
>>>> + update_parity = false;
>>>> + break;
>>>> + }
>>>> +
>>>> + pr_debug("%s:%*s reading data member disk %s sector %llu\n",
>>>> + __func__, indent, "", bdevname(rdev->bdev, b),
>>>> + (unsigned long long)sector);
>>>> + if (!sync_page_io(rdev, sector, block_size, page2,
>>>> + REQ_OP_READ, 0, false)) {
>>>> + md_error(mddev, rdev);
>>>> + pr_debug("%s:%*s read failed!\n", __func__,
>>>> + indent, "");
>>>> + ret = -EIO;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + ppl_xor(block_size, page1, page2, page1);
>>>> +
>>>> + indent -= 2;
>>>> + }
>>>> +
>>>> + if (!update_parity)
>>>> + continue;
>>>> +
>>>> + if (pp_size > 0) {
>>>> + pr_debug("%s:%*s reading pp disk sector %llu\n",
>>>> + __func__, indent, "",
>>>> + (unsigned long long)(ppl_sector + i));
>>>> + if (!sync_page_io(log->rdev,
>>>> + ppl_sector - log->rdev->data_offset + i,
>>>> + block_size, page2, REQ_OP_READ, 0,
>>>> + false)) {
>>>> + pr_debug("%s:%*s read failed!\n", __func__,
>>>> + indent, "");
>>>> + md_error(mddev, log->rdev);
>>>> + ret = -EIO;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + ppl_xor(block_size, page1, page2, page1);
>>>> + }
>>>> +
>>>> + /* map raid sector to parity disk */
>>>> + parity_sector = raid5_compute_sector(conf, r_sector_first + i,
>>>> + 0, &disk, &sh);
>>>> + BUG_ON(sh.pd_idx != le32_to_cpu(e->parity_disk));
>>>> + parity_rdev = conf->disks[sh.pd_idx].rdev;
>>>> +
>>>> + BUG_ON(parity_rdev->bdev->bd_dev != log->rdev->bdev->bd_dev);
>>>> + pr_debug("%s:%*s write parity at sector %llu, disk %s\n",
>>>> + __func__, indent, "",
>>>> + (unsigned long long)parity_sector,
>>>> + bdevname(parity_rdev->bdev, b));
>>>> + if (!sync_page_io(parity_rdev, parity_sector, block_size,
>>>> + page1, REQ_OP_WRITE, 0, false)) {
>>>> + pr_debug("%s:%*s parity write error!\n", __func__,
>>>> + indent, "");
>>>> + md_error(mddev, parity_rdev);
>>>> + ret = -EIO;
>>>> + goto out;
>>>> + }
>>>> + }
>>>> +out:
>>>> + __free_pages(pages, 1);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int ppl_recover(struct ppl_log *log, struct ppl_header *pplhdr)
>>>> +{
>>>> + struct ppl_conf *ppl_conf = log->ppl_conf;
>>>> + struct md_rdev *rdev = log->rdev;
>>>> + struct mddev *mddev = rdev->mddev;
>>>> + sector_t ppl_sector = rdev->ppl.sector + (PPL_HEADER_SIZE >> 9);
>>>> + struct page *page;
>>>> + int i;
>>>> + int ret = 0;
>>>> +
>>>> + page = alloc_page(GFP_KERNEL);
>>>> + if (!page)
>>>> + return -ENOMEM;
>>>> +
>>>> + /* iterate through all PPL entries saved */
>>>> + for (i = 0; i < le32_to_cpu(pplhdr->entries_count); i++) {
>>>> + struct ppl_header_entry *e = &pplhdr->entries[i];
>>>> + u32 pp_size = le32_to_cpu(e->pp_size);
>>>> + sector_t sector = ppl_sector;
>>>> + int ppl_entry_sectors = pp_size >> 9;
>>>> + u32 crc, crc_stored;
>>>> +
>>>> + pr_debug("%s: disk: %d entry: %d ppl_sector: %llu pp_size: %u\n",
>>>> + __func__, rdev->raid_disk, i,
>>>> + (unsigned long long)ppl_sector, pp_size);
>>>> +
>>>> + crc = ~0;
>>>> + crc_stored = le32_to_cpu(e->checksum);
>>>> +
>>>> + /* read parial parity for this entry and calculate its checksum */
>>>> + while (pp_size) {
>>>> + int s = pp_size > PAGE_SIZE ? PAGE_SIZE : pp_size;
>>>> +
>>>> + if (!sync_page_io(rdev, sector - rdev->data_offset,
>>>> + s, page, REQ_OP_READ, 0, false)) {
>>>> + md_error(mddev, rdev);
>>>> + ret = -EIO;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + crc = crc32c_le(crc, page_address(page), s);
>>>> +
>>>> + pp_size -= s;
>>>> + sector += s >> 9;
>>>> + }
>>>> +
>>>> + crc = ~crc;
>>>> +
>>>> + if (crc != crc_stored) {
>>>> + /*
>>>> + * Don't recover this entry if the checksum does not
>>>> + * match, but keep going and try to recover other
>>>> + * entries.
>>>> + */
>>>> + pr_debug("%s: ppl entry crc does not match: stored: 0x%x calculated: 0x%x\n",
>>>> + __func__, crc_stored, crc);
>>>> + ppl_conf->mismatch_count++;
>>>> + } else {
>>>> + ret = ppl_recover_entry(log, e, ppl_sector);
>>>> + if (ret)
>>>> + goto out;
>>>> + ppl_conf->recovered_entries++;
>>>> + }
>>>> +
>>>> + ppl_sector += ppl_entry_sectors;
>>>> + }
>>>> +out:
>>>> + __free_page(page);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int ppl_write_empty_header(struct ppl_log *log)
>>>> +{
>>>> + struct page *page;
>>>> + struct ppl_header *pplhdr;
>>>> + struct md_rdev *rdev = log->rdev;
>>>> + int ret = 0;
>>>> +
>>>> + pr_debug("%s: disk: %d ppl_sector: %llu\n", __func__,
>>>> + rdev->raid_disk, (unsigned long long)rdev->ppl.sector);
>>>> +
>>>> + page = alloc_page(GFP_NOIO | __GFP_ZERO);
>>>> + if (!page)
>>>> + return -ENOMEM;
>>>> +
>>>> + pplhdr = page_address(page);
>>>> + memset(pplhdr->reserved, 0xff, PPL_HDR_RESERVED);
>>>> + pplhdr->signature = cpu_to_le32(log->ppl_conf->signature);
>>>> + pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PAGE_SIZE));
>>>> +
>>>> + if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
>>>> + PPL_HEADER_SIZE, page, REQ_OP_WRITE, 0, false)) {
>>>
>>> write with FUA? otherwise, the empty header might not set down in the disks.
>>
>> OK.
>>
>>>> + md_error(rdev->mddev, rdev);
>>>> + ret = -EIO;
>>>> + }
>>>> +
>>>> + __free_page(page);
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int ppl_load_distributed(struct ppl_log *log)
>>>> +{
>>>> + struct ppl_conf *ppl_conf = log->ppl_conf;
>>>> + struct md_rdev *rdev = log->rdev;
>>>> + struct mddev *mddev = rdev->mddev;
>>>> + struct page *page;
>>>> + struct ppl_header *pplhdr;
>>>> + u32 crc, crc_stored;
>>>> + u32 signature;
>>>> + int ret = 0;
>>>> +
>>>> + pr_debug("%s: disk: %d\n", __func__, rdev->raid_disk);
>>>> +
>>>> + /* read PPL header */
>>>> + page = alloc_page(GFP_KERNEL);
>>>> + if (!page)
>>>> + return -ENOMEM;
>>>> +
>>>> + if (!sync_page_io(rdev, rdev->ppl.sector - rdev->data_offset,
>>>> + PAGE_SIZE, page, REQ_OP_READ, 0, false)) {
>>>> + md_error(mddev, rdev);
>>>> + ret = -EIO;
>>>> + goto out;
>>>> + }
>>>> + pplhdr = page_address(page);
>>>> +
>>>> + /* check header validity */
>>>> + crc_stored = le32_to_cpu(pplhdr->checksum);
>>>> + pplhdr->checksum = 0;
>>>> + crc = ~crc32c_le(~0, pplhdr, PAGE_SIZE);
>>>> +
>>>> + if (crc_stored != crc) {
>>>> + pr_debug("%s: ppl header crc does not match: stored: 0x%x calculated: 0x%x\n",
>>>> + __func__, crc_stored, crc);
>>>> + ppl_conf->mismatch_count++;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + signature = le32_to_cpu(pplhdr->signature);
>>>> +
>>>> + if (mddev->external) {
>>>> + /*
>>>> + * For external metadata the header signature is set and
>>>> + * validated in userspace.
>>>> + */
>>>> + ppl_conf->signature = signature;
>>>> + } else if (ppl_conf->signature != signature) {
>>>> + pr_debug("%s: ppl header signature does not match: stored: 0x%x configured: 0x%x\n",
>>>> + __func__, signature, ppl_conf->signature);
>>>> + ppl_conf->mismatch_count++;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + /* attempt to recover from log if we are starting a dirty array */
>>>> + if (!mddev->pers && mddev->recovery_cp != MaxSector)
>>>> + ret = ppl_recover(log, pplhdr);
>>>
>>> when could mddev->pers be null?
>>
>> When the array is inactive - we are starting the array with ppl, not
>> enabling ppl at runtime.
>
> Didn't follow this. Can explain more?
mddev->pers is null if this is executed from md_run()/raid5_run().
That's when the array is just about to be started and we want to perform
the ppl recovery. If this is called from
raid5_change_consistency_policy(), mddev->pers is not null and recovery
should not be attempted, because the array is active.
Thanks,
Artur
^ permalink raw reply [flat|nested] 25+ messages in thread
end of thread, other threads:[~2017-03-02 8:40 UTC | newest]
Thread overview: 25+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-02-21 19:43 [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
2017-02-21 19:43 ` [PATCH v4 1/7] md: superblock changes for PPL Artur Paszkiewicz
2017-02-21 19:43 ` [PATCH v4 2/7] raid5: calculate partial parity for a stripe Artur Paszkiewicz
2017-02-27 23:45 ` Shaohua Li
2017-03-01 16:12 ` Artur Paszkiewicz
2017-02-21 19:43 ` [PATCH v4 3/7] raid5-ppl: Partial Parity Log write logging implementation Artur Paszkiewicz
2017-02-28 0:04 ` Shaohua Li
2017-03-01 16:13 ` Artur Paszkiewicz
2017-03-01 17:51 ` Shaohua Li
2017-02-21 19:43 ` [PATCH v4 4/7] md: add sysfs entries for PPL Artur Paszkiewicz
2017-02-28 0:37 ` Shaohua Li
2017-03-01 16:13 ` Artur Paszkiewicz
2017-02-21 19:43 ` [PATCH v4 5/7] raid5-ppl: load and recover the log Artur Paszkiewicz
2017-02-28 1:12 ` Shaohua Li
2017-03-01 16:14 ` Artur Paszkiewicz
2017-03-01 17:59 ` Shaohua Li
2017-03-02 8:40 ` Artur Paszkiewicz
2017-02-21 19:44 ` [PATCH v4 6/7] raid5-ppl: support disk hot add/remove with PPL Artur Paszkiewicz
2017-02-28 1:22 ` Shaohua Li
2017-03-01 16:14 ` Artur Paszkiewicz
2017-02-21 19:44 ` [PATCH v4 7/7] raid5-ppl: runtime PPL enabling or disabling Artur Paszkiewicz
2017-02-28 1:31 ` Shaohua Li
2017-03-01 16:14 ` Artur Paszkiewicz
2017-02-28 1:35 ` [PATCH v4 0/7] Partial Parity Log for MD RAID 5 Shaohua Li
2017-03-01 16:12 ` Artur Paszkiewicz
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