[PATCH v1 0/6] btrfs: scrub

[PATCH v1 0/6] btrfs: scrub

[Arne Jansen]

This series adds an initial implementation for scrub. It works quite
straightforward. The usermode issues an ioctl for each device in the
fs. For each device, it enumerates the allocated device chunks. For
each chunk, the contained extents are enumerated and the data checksums
fetched. The extents are read sequentially and the checksums verified.
If an error occurs (checksum or EIO), a good copy is searched for. If
one is found, the bad copy will be rewritten.
All enumerations happen from the commit roots. During a transaction
commit, the scrubs get paused and afterwards continue from the new
roots.
For future improvements please see the inline comments.

The accompanying user mode patches will follow shortly.

Thanks,
Arne

Arne Jansen (5):
Jan Schmidt (1):
  btrfs: add parameter to btrfs_lookup_csum_range
  btrfs: make struct map_lookup public
  btrfs: add state information for scrub
  btrfs: add scrub code and prototypes
  btrfs: sync scrub with commit & device removal
  btrfs: new ioctls for scrub

 fs/btrfs/Makefile      |    2 +-
 fs/btrfs/ctree.h       |   44 ++-
 fs/btrfs/disk-io.c     |   16 +
 fs/btrfs/file-item.c   |    8 +-
 fs/btrfs/inode.c       |    2 +-
 fs/btrfs/ioctl.c       |   85 +++
 fs/btrfs/ioctl.h       |   36 ++
 fs/btrfs/relocation.c  |    2 +-
 fs/btrfs/scrub.c       | 1462 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/transaction.c |    3 +
 fs/btrfs/tree-log.c    |    6 +-
 fs/btrfs/volumes.c     |   16 +-
 fs/btrfs/volumes.h     |   17 +
 13 files changed, 1677 insertions(+), 22 deletions(-)
 create mode 100644 fs/btrfs/scrub.c

-- 
1.7.3.4

[PATCH v1 1/6] btrfs: add parameter to btrfs_lookup_csum_range

[Arne Jansen]

A parameter is added to search the commit root instead of the live root.

Signed-off-by: Arne Jansen <sensille@gmx.net>
---
 fs/btrfs/ctree.h      |    4 ++--
 fs/btrfs/file-item.c  |    8 +++++++-
 fs/btrfs/inode.c      |    2 +-
 fs/btrfs/relocation.c |    2 +-
 fs/btrfs/tree-log.c   |    4 ++--
 5 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7219537..1c9a2ef 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2447,8 +2447,8 @@ struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
 int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root, struct btrfs_path *path,
 			u64 isize);
-int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start,
-			     u64 end, struct list_head *list);
+int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
+			     struct list_head *list, int search_commit);
 /* inode.c */
 
 /* RHEL and EL kernels have a patch that renames PG_checked to FsMisc */
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 4f19a3e..9643d6e 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -263,7 +263,7 @@ int btrfs_lookup_bio_sums_dio(struct btrfs_root *root, struct inode *inode,
 }
 
 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
-			     struct list_head *list)
+			     struct list_head *list, int search_commit)
 {
 	struct btrfs_key key;
 	struct btrfs_path *path;
@@ -280,6 +280,12 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 	path = btrfs_alloc_path();
 	BUG_ON(!path);
 
+	if (search_commit) {
+		path->skip_locking = 1;
+		path->reada = 2;
+		path->search_commit_root = 1;
+	}
+
 	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 	key.offset = start;
 	key.type = BTRFS_EXTENT_CSUM_KEY;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8d392ed..597b7ca 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1001,7 +1001,7 @@ static noinline int csum_exist_in_range(struct btrfs_root *root,
 	LIST_HEAD(list);
 
 	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, bytenr,
-				       bytenr + num_bytes - 1, &list);
+				       bytenr + num_bytes - 1, &list, 0);
 	if (ret == 0 && list_empty(&list))
 		return 0;
 
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 0825e4e..fa9c0a9 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4225,7 +4225,7 @@ int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
 
 	disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
 	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
-				       disk_bytenr + len - 1, &list);
+				       disk_bytenr + len - 1, &list, 0);
 
 	while (!list_empty(&list)) {
 		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index a4bbb85..1f6788f 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -614,7 +614,7 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
 
 			ret = btrfs_lookup_csums_range(root->log_root,
 						csum_start, csum_end - 1,
-						&ordered_sums);
+						&ordered_sums, 0);
 			BUG_ON(ret);
 			while (!list_empty(&ordered_sums)) {
 				struct btrfs_ordered_sum *sums;
@@ -2691,7 +2691,7 @@ static noinline int copy_items(struct btrfs_trans_handle *trans,
 				ret = btrfs_lookup_csums_range(
 						log->fs_info->csum_root,
 						ds + cs, ds + cs + cl - 1,
-						&ordered_sums);
+						&ordered_sums, 0);
 				BUG_ON(ret);
 			}
 		}
-- 
1.7.3.4

[PATCH v1 2/6] btrfs: make struct map_lookup public

[Arne Jansen]

definition of struct map_lookup moved from volumes.c to the header

Signed-off-by: Arne Jansen <sensille@gmx.net>
---
 fs/btrfs/volumes.c |   14 --------------
 fs/btrfs/volumes.h |   14 ++++++++++++++
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index dadaaa8..acd7930 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -33,25 +33,11 @@
 #include "volumes.h"
 #include "async-thread.h"
 
-struct map_lookup {
-	u64 type;
-	int io_align;
-	int io_width;
-	int stripe_len;
-	int sector_size;
-	int num_stripes;
-	int sub_stripes;
-	struct btrfs_bio_stripe stripes[];
-};
-
 static int init_first_rw_device(struct btrfs_trans_handle *trans,
 				struct btrfs_root *root,
 				struct btrfs_device *device);
 static int btrfs_relocate_sys_chunks(struct btrfs_root *root);
 
-#define map_lookup_size(n) (sizeof(struct map_lookup) + \
-			    (sizeof(struct btrfs_bio_stripe) * (n)))
-
 static DEFINE_MUTEX(uuid_mutex);
 static LIST_HEAD(fs_uuids);
 
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 7af6144..0ccc982 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -129,6 +129,20 @@ struct btrfs_bio_stripe {
 	u64 physical;
 };
 
+struct map_lookup {
+	u64 type;
+	int io_align;
+	int io_width;
+	int stripe_len;
+	int sector_size;
+	int num_stripes;
+	int sub_stripes;
+	struct btrfs_bio_stripe stripes[];
+};
+
+#define map_lookup_size(n) (sizeof(struct map_lookup) + \
+			    (sizeof(struct btrfs_bio_stripe) * (n)))
+
 struct btrfs_multi_bio {
 	atomic_t stripes_pending;
 	bio_end_io_t *end_io;
-- 
1.7.3.4

[PATCH v1 3/6] btrfs: add state information for scrub

[Arne Jansen]

Add structures and state information needed for scrub

Signed-off-by: Arne Jansen <sensille@gmx.net>
---
 fs/btrfs/ctree.h   |   26 ++++++++++++++++++++++++++
 fs/btrfs/disk-io.c |   15 +++++++++++++++
 fs/btrfs/ioctl.h   |   29 +++++++++++++++++++++++++++++
 fs/btrfs/volumes.h |    3 +++
 4 files changed, 73 insertions(+), 0 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1c9a2ef..e014432 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -23,6 +23,7 @@
 #include <linux/mm.h>
 #include <linux/highmem.h>
 #include <linux/fs.h>
+#include <linux/rwsem.h>
 #include <linux/completion.h>
 #include <linux/backing-dev.h>
 #include <linux/wait.h>
@@ -32,6 +33,7 @@
 #include "extent_io.h"
 #include "extent_map.h"
 #include "async-thread.h"
+#include "ioctl.h"
 
 struct btrfs_trans_handle;
 struct btrfs_transaction;
@@ -48,6 +50,8 @@ struct btrfs_ordered_sum;
 
 #define BTRFS_COMPAT_EXTENT_TREE_V0
 
+#define SCRUB_BTRFS_WORKER
+
 /*
  * files bigger than this get some pre-flushing when they are added
  * to the ordered operations list.  That way we limit the total
@@ -508,6 +512,12 @@ struct btrfs_extent_item_v0 {
 /* use full backrefs for extent pointers in the block */
 #define BTRFS_BLOCK_FLAG_FULL_BACKREF	(1ULL << 8)
 
+/*
+ * this flag is only used internally by scrub and may be changed at any time
+ * it is only declared here to avoid collisions
+ */
+#define BTRFS_EXTENT_FLAG_SUPER		(1ULL << 48)
+
 struct btrfs_tree_block_info {
 	struct btrfs_disk_key key;
 	u8 level;
@@ -1067,6 +1077,22 @@ struct btrfs_fs_info {
 
 	void *bdev_holder;
 
+	/* private scrub information */
+	struct mutex scrub_lock;
+	struct scrub_info *scrub_info;
+	atomic_t scrubs_running;
+	atomic_t scrub_pause_req;
+	atomic_t scrubs_paused;
+	atomic_t scrub_cancel_req;
+	wait_queue_head_t scrub_pause_wait;
+	struct rw_semaphore scrub_super_lock;
+	int scrub_workers_refcnt;
+#ifdef SCRUB_BTRFS_WORKER
+	struct btrfs_workers scrub_workers;
+#else
+	struct workqueue_struct *scrub_workers;
+#endif
+
 	/* filesystem state */
 	u64 fs_state;
 };
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3e1ea3e..061a48a 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1677,6 +1677,21 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 	INIT_LIST_HEAD(&fs_info->ordered_extents);
 	spin_lock_init(&fs_info->ordered_extent_lock);
 
+	mutex_init(&fs_info->scrub_lock);
+	atomic_set(&fs_info->scrubs_running, 0);
+	atomic_set(&fs_info->scrub_pause_req, 0);
+	atomic_set(&fs_info->scrubs_paused, 0);
+	atomic_set(&fs_info->scrub_cancel_req, 0);
+	init_waitqueue_head(&fs_info->scrub_pause_wait);
+	init_rwsem(&fs_info->scrub_super_lock);
+	fs_info->scrub_workers_refcnt = 0;
+#ifdef SCRUB_BTRFS_WORKER
+	btrfs_init_workers(&fs_info->scrub_workers, "scrub",
+			   fs_info->thread_pool_size, &fs_info->generic_worker);
+#else
+	fs_info->scrub_workers = NULL;
+#endif
+
 	sb->s_blocksize = 4096;
 	sb->s_blocksize_bits = blksize_bits(4096);
 	sb->s_bdi = &fs_info->bdi;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 8fb3821..f7bf177 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -42,6 +42,35 @@ struct btrfs_ioctl_vol_args_v2 {
 	char name[BTRFS_SUBVOL_NAME_MAX + 1];
 };
 
+struct btrfs_scrub_progress {
+	__u64 data_extents_scrubbed;
+	__u64 tree_extents_scrubbed;
+	__u64 data_bytes_scrubbed;
+	__u64 tree_bytes_scrubbed;
+	__u64 read_errors;
+	__u64 csum_errors;
+	__u64 verify_errors;
+	__u64 no_csum;
+	__u64 csum_discards;
+	__u64 super_errors;
+	__u64 malloc_errors;
+	__u64 uncorrectable_errors;
+	__u64 corrected_errors;
+	__u64 last_physical;
+};
+
+struct btrfs_ioctl_scrub_args {
+	__u64 devid;
+	__u64 start;
+	__u64 end;
+	struct btrfs_scrub_progress progress;
+};
+
+struct btrfs_ioctl_dev_info_args {
+	__u64 num_devices;
+	__u64 max_id;
+};
+
 #define BTRFS_INO_LOOKUP_PATH_MAX 4080
 struct btrfs_ioctl_ino_lookup_args {
 	__u64 treeid;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 0ccc982..92204d9 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -86,6 +86,9 @@ struct btrfs_device {
 	/* physical drive uuid (or lvm uuid) */
 	u8 uuid[BTRFS_UUID_SIZE];
 
+	/* per-device scrub information */
+	struct scrub_dev *scrub_device;
+
 	struct btrfs_work work;
 };
 
-- 
1.7.3.4

[PATCH v1 4/6] btrfs: add scrub code and prototypes

[Arne Jansen]

This is the main scrub code.

Signed-off-by: Arne Jansen <sensille@gmx.net>
---
 fs/btrfs/Makefile |    2 +-
 fs/btrfs/ctree.h  |   14 +
 fs/btrfs/scrub.c  | 1462 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1477 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 31610ea..8fda313 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -7,4 +7,4 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
 	   extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
 	   extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \
 	   export.o tree-log.o acl.o free-space-cache.o zlib.o lzo.o \
-	   compression.o delayed-ref.o relocation.o
+	   compression.o delayed-ref.o relocation.o scrub.o
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e014432..8b726ab 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2633,4 +2633,18 @@ void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
 			      u64 *bytes_to_reserve);
 void btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
 			      struct btrfs_pending_snapshot *pending);
+
+/* scrub.c */
+int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
+                    struct btrfs_scrub_progress *progress);
+int btrfs_scrub_pause(struct btrfs_root *root);
+int btrfs_scrub_pause_super(struct btrfs_root *root);
+int btrfs_scrub_continue(struct btrfs_root *root);
+int btrfs_scrub_continue_super(struct btrfs_root *root);
+int btrfs_scrub_cancel(struct btrfs_root *root);
+int btrfs_scrub_cancel_dev(struct btrfs_root *root, struct btrfs_device *dev);
+int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid);
+int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
+                         struct btrfs_scrub_progress *progress);
+
 #endif
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
new file mode 100644
index 0000000..9c5b538
--- /dev/null
+++ b/fs/btrfs/scrub.c
@@ -0,0 +1,1462 @@
+/*
+ * Copyright (C) 2011 STRATO.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that 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.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/sched.h>
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/blkdev.h>
+#include <linux/rbtree.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include "ctree.h"
+#include "volumes.h"
+#include "disk-io.h"
+#include "ordered-data.h"
+
+/*
+ * This is only the first step towards a full-features scrub. It reads all
+ * extent and super block and verifies the checksums. In case a bad checksum
+ * is found or the extent cannot be read, good data will be written back if
+ * any can be found.
+ *
+ * Future enhancements:
+ *  - To enhance the performance, better read-ahead strategies for the
+ *    extent-tree can be employed.
+ *  - In case an unrepairable extent is encountered, track which files are
+ *    affected and report them
+ *  - In case of a read error on files with nodatasum, map the file and read
+ *    the extent to trigger a writeback of the good copy
+ *  - track and record media errors, throw out bad devices
+ *  - add a readonly mode
+ */
+
+#ifdef SCRUB_BTRFS_WORKER
+typedef struct btrfs_work scrub_work_t;
+#define SCRUB_INIT_WORK(work, fn) do { (work)->func = (fn); } while (0)
+#define SCRUB_QUEUE_WORK(wq, w) do { btrfs_queue_worker(&(wq), w); } while (0)
+#else
+typedef struct work_struct scrub_work_t;
+#define SCRUB_INIT_WORK INIT_WORK
+#define SCRUB_QUEUE_WORK queue_work
+#endif
+
+struct scrub_bio;
+struct scrub_page;
+struct scrub_dev;
+struct scrub_fixup;
+static void scrub_bio_end_io(struct bio *bio, int err);
+static void scrub_checksum(scrub_work_t *work);
+static int scrub_checksum_data(struct scrub_dev *sdev,
+                               struct scrub_page *spag, void *buffer);
+static int scrub_checksum_tree_block(struct scrub_dev *sdev,
+                                     struct scrub_page *spag, u64 logical,
+                                     void *buffer);
+static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer);
+static void scrub_recheck_end_io(struct bio *bio, int err);
+static void scrub_fixup_worker(scrub_work_t *work);
+static void scrub_fixup(struct scrub_fixup *fixup);
+
+#define SCRUB_PAGES_PER_BIO	16	/* 64k per bio */
+#define SCRUB_BIOS_PER_DEV	16	/* 1 MB per device in flight */
+
+struct scrub_page {
+	u64			flags;  /* extent flags */
+	u64			generation;
+	u64			mirror_num;
+	int			have_csum;
+	u8			csum[BTRFS_CSUM_SIZE];
+};
+
+struct scrub_bio {
+	int			index;
+	struct scrub_dev	*sdev;
+	struct bio		*bio;
+	int			err;
+	u64			logical;
+	u64			physical;
+	struct scrub_page	spag[SCRUB_PAGES_PER_BIO];
+	u64			count;
+	int			next_free;
+	scrub_work_t		work;
+};
+
+struct scrub_dev {
+	struct scrub_bio	bios[SCRUB_BIOS_PER_DEV];
+	struct btrfs_device	*dev;
+	int			first_free;
+	int			curr;
+	atomic_t		in_flight;
+	spinlock_t		list_lock;
+	wait_queue_head_t	list_wait;
+	u16			csum_size;
+	struct list_head	csum_list;
+	atomic_t		cancel_req;
+	/*
+	 * statistics
+	 */
+	struct btrfs_scrub_progress stat;
+	spinlock_t		stat_lock;
+};
+
+struct scrub_fixup {
+	struct scrub_dev	*sdev;
+	struct bio		*bio;
+	u64			logical;
+	u64			physical;
+	struct scrub_page	spag;
+	scrub_work_t		work;
+	int			err;
+	int			recheck;
+};
+
+static void scrub_free_csums(struct scrub_dev *sdev)
+{
+	while(!list_empty(&sdev->csum_list)) {
+		struct btrfs_ordered_sum *sum;
+		sum = list_first_entry(&sdev->csum_list,
+		                       struct btrfs_ordered_sum, list);
+		list_del(&sum->list);
+		kfree(sum);
+	}
+}
+
+static noinline_for_stack void scrub_free_dev(struct scrub_dev *sdev)
+{
+	int i;
+	int j;
+	struct page *last_page;
+
+	if (!sdev)
+		return;
+
+	for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
+		struct bio *bio = sdev->bios[i].bio;
+		if (bio)
+			break;
+		
+		last_page = NULL;
+		for (j = 0; j < bio->bi_vcnt; ++j) {
+			if (bio->bi_io_vec[i].bv_page == last_page)
+				continue;
+			last_page = bio->bi_io_vec[i].bv_page;
+			__free_page(last_page);
+		}
+		bio_put(sdev->bios[i].bio);
+	}
+
+	scrub_free_csums(sdev);
+	kfree(sdev);
+}
+
+static noinline_for_stack
+struct scrub_dev *scrub_setup_dev(struct btrfs_device *dev)
+{
+	struct scrub_dev *sdev;
+	int		i;
+	int		j;
+	int		ret;
+	struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
+	sdev = kzalloc(sizeof(*sdev), GFP_NOFS);
+	if (!sdev)
+		goto nomem;
+	sdev->dev = dev;
+	for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
+		struct bio *bio;
+
+		bio = bio_alloc(GFP_NOFS, SCRUB_PAGES_PER_BIO);
+		if (!bio)
+			goto nomem;
+
+		sdev->bios[i].index = i;
+		sdev->bios[i].sdev = sdev;
+		sdev->bios[i].bio = bio;
+		sdev->bios[i].count = 0;
+		SCRUB_INIT_WORK(&sdev->bios[i].work, scrub_checksum);
+		bio->bi_private = sdev->bios + i;
+		bio->bi_end_io = scrub_bio_end_io;
+		bio->bi_sector = 0;
+		bio->bi_bdev = dev->bdev;
+		bio->bi_size = 0;
+
+		for (j = 0; j < SCRUB_PAGES_PER_BIO; ++j) {
+			struct page *page;
+			page = alloc_page(GFP_NOFS);
+			if (!page)
+				goto nomem;
+
+			ret = bio_add_page(bio, page, PAGE_SIZE, 0);
+			if (!ret)
+				goto nomem;
+		}
+		WARN_ON(bio->bi_vcnt != SCRUB_PAGES_PER_BIO);
+
+		if (i != SCRUB_BIOS_PER_DEV-1)
+			sdev->bios[i].next_free = i + 1;
+		 else
+			sdev->bios[i].next_free = -1;
+	}
+	sdev->first_free = 0;
+	sdev->curr = -1;
+	atomic_set(&sdev->in_flight, 0);
+	atomic_set(&sdev->cancel_req, 0);
+	sdev->csum_size = btrfs_super_csum_size(&fs_info->super_copy);
+	INIT_LIST_HEAD(&sdev->csum_list);
+	
+	spin_lock_init(&sdev->list_lock);
+	spin_lock_init(&sdev->stat_lock);
+	init_waitqueue_head(&sdev->list_wait);
+	return sdev;
+
+nomem:
+	scrub_free_dev(sdev);
+	return ERR_PTR(-ENOMEM);
+}
+
+/*
+ * scrub_recheck_error gets called when either verification of the page
+ * failed or the bio failed to read, e.g. with EIO. In the latter case,
+ * recheck_error gets called for every page in the bio, even though only
+ * one may be bad
+ */
+static void scrub_recheck_error(struct scrub_bio *sbio, int ix)
+{
+	struct scrub_dev *sdev = sbio->sdev;
+	struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
+	struct bio *bio = NULL;
+	struct page *page = NULL;
+	struct scrub_fixup *fixup = NULL;
+	int ret;
+
+	/*
+	 * while we're in here we do not want the transaction to commit.
+	 * To prevent it, we increment scrubs_running. scrub_pause will
+	 * have to wait until we're finished
+	 */
+	mutex_lock(&fs_info->scrub_lock);
+	atomic_inc(&fs_info->scrubs_running);
+	mutex_unlock(&fs_info->scrub_lock);
+
+	fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
+	if (!fixup)
+		goto malloc_error;
+
+	fixup->logical = sbio->logical + ix * PAGE_SIZE;
+	fixup->physical = sbio->physical + ix * PAGE_SIZE;
+	fixup->spag = sbio->spag[ix];
+	fixup->sdev = sdev;
+
+	bio = bio_alloc(GFP_NOFS, 1);
+	if (!bio)
+		goto malloc_error;
+	bio->bi_private = fixup;
+	bio->bi_size = 0;
+	bio->bi_bdev = sdev->dev->bdev;	/* FIXME: temporary for add_page */
+	fixup->bio = bio;
+	fixup->recheck = 0;
+
+	page = alloc_page(GFP_NOFS);
+	if (!page)
+		goto malloc_error;
+
+	ret = bio_add_page(bio, page, PAGE_SIZE, 0);
+	if (!ret)
+		goto malloc_error;
+
+	if (!sbio->err) {
+		/*
+		 * shorter path: just a checksum error, go ahead and correct it
+		 */
+		scrub_fixup_worker(&fixup->work);
+		return;
+	}
+
+	/*
+	 * an I/O-error occured for one of the blocks in the bio, not
+	 * necessarily for this one, so first try to read it separately
+	 */
+	SCRUB_INIT_WORK(&fixup->work, scrub_fixup_worker);
+	fixup->recheck = 1;
+	bio->bi_end_io = scrub_recheck_end_io;
+	bio->bi_sector = fixup->physical >> 9;
+	bio->bi_bdev = sdev->dev->bdev;
+	submit_bio(0, bio);
+
+	return;
+
+malloc_error:
+	if (bio) 
+		bio_put(bio);
+	if (page)
+		__free_page(page);
+	if (fixup)
+		kfree(fixup);
+	spin_lock(&sdev->stat_lock);
+	++sdev->stat.malloc_errors;
+	spin_unlock(&sdev->stat_lock);
+	mutex_lock(&fs_info->scrub_lock);
+	atomic_dec(&fs_info->scrubs_running);
+	mutex_unlock(&fs_info->scrub_lock);
+	wake_up(&fs_info->scrub_pause_wait);
+}
+
+static void scrub_recheck_end_io(struct bio *bio, int err)
+{
+	struct scrub_fixup *fixup = bio->bi_private;
+	struct btrfs_fs_info *fs_info = fixup->sdev->dev->dev_root->fs_info;
+
+	fixup->err = err;
+	SCRUB_QUEUE_WORK(fs_info->scrub_workers, &fixup->work);
+}
+
+static int scrub_fixup_check(struct scrub_fixup *fixup)
+{
+	int ret = 1;
+	struct page *page;
+	void *buffer;
+	u64 flags = fixup->spag.flags;
+
+	page = fixup->bio->bi_io_vec[0].bv_page;
+	buffer = kmap_atomic(page, KM_USER0);
+	if (flags & BTRFS_EXTENT_FLAG_DATA) {
+		ret = scrub_checksum_data(fixup->sdev,
+					  &fixup->spag, buffer);
+	} else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+		ret = scrub_checksum_tree_block(fixup->sdev,
+						&fixup->spag,
+						fixup->logical,
+						buffer);
+	} else {
+		WARN_ON(1);
+	}
+	kunmap_atomic(buffer, KM_USER0);
+
+	return ret;
+}
+
+static void scrub_fixup_worker(scrub_work_t *work)
+{
+	struct scrub_fixup *fixup;
+	struct btrfs_fs_info *fs_info;
+	u64 flags;
+	int ret = 1;
+
+	fixup = container_of(work, struct scrub_fixup, work);
+	fs_info = fixup->sdev->dev->dev_root->fs_info;
+	flags = fixup->spag.flags;
+
+	if (fixup->recheck && fixup->err == 0)
+		ret = scrub_fixup_check(fixup);
+
+	if (ret || fixup->err)
+		scrub_fixup(fixup);
+
+	__free_page(fixup->bio->bi_io_vec[0].bv_page);
+	bio_put(fixup->bio);
+
+	mutex_lock(&fs_info->scrub_lock);
+	atomic_dec(&fs_info->scrubs_running);
+	mutex_unlock(&fs_info->scrub_lock);
+	wake_up(&fs_info->scrub_pause_wait);
+
+	kfree(fixup);
+}
+
+static void scrub_fixup_end_io(struct bio *bio, int err)
+{
+	complete((struct completion *)bio->bi_private);
+}
+
+static void scrub_fixup(struct scrub_fixup *fixup)
+{
+	struct scrub_dev *sdev = fixup->sdev;
+	struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
+	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree; 
+	struct btrfs_multi_bio *multi = NULL;
+	struct bio *bio = fixup->bio;
+	u64 length;
+	int i;
+	int ret;
+	DECLARE_COMPLETION_ONSTACK(complete);
+
+	if ((fixup->spag.flags & BTRFS_EXTENT_FLAG_DATA) &&
+	    (fixup->spag.have_csum == 0)) {
+		/*
+		 * nodatasum, don't try to fix anything
+		 * FIXME: we can do better, open the inode and trigger a
+		 * writeback
+		 */
+		goto uncorrectable;
+	}
+
+	length = PAGE_SIZE;
+	ret = btrfs_map_block(map_tree, REQ_WRITE, fixup->logical, &length,
+	                      &multi, 0);
+	if (ret || !multi || length < PAGE_SIZE) {
+		printk(KERN_ERR
+		       "scrub_fixup: btrfs_map_block failed us for %lld\n",
+		       fixup->logical);
+		WARN_ON(1);
+		return;
+	}
+
+	if (multi->num_stripes == 1) {
+		/* there aren't any replicas */
+		goto uncorrectable;
+	}
+
+	/*
+	 * first find a good copy
+	 */
+	for (i = 0; i < multi->num_stripes; ++i) {
+		if (i == fixup->spag.mirror_num)
+			continue;
+
+		bio->bi_sector = multi->stripes[i].physical >> 9;
+		bio->bi_bdev = multi->stripes[i].dev->bdev;
+		bio->bi_size = PAGE_SIZE;
+		bio->bi_next = NULL;
+		bio->bi_flags = 1 << BIO_UPTODATE;
+		bio->bi_comp_cpu = -1;
+		bio->bi_end_io = scrub_fixup_end_io;
+		bio->bi_private = &complete;
+
+		submit_bio(0, bio);
+
+		wait_for_completion(&complete);
+
+		if (~bio->bi_flags & BIO_UPTODATE)
+			/* I/O-error, this is not a good copy */
+			continue;
+
+		ret = scrub_fixup_check(fixup);
+		if (ret == 0)
+			break;
+	}
+	if (i == multi->num_stripes)
+		goto uncorrectable;
+
+	/*
+	 * the bio now contains good data, write it back
+	 */
+	bio->bi_sector = fixup->physical >> 9;
+	bio->bi_bdev = sdev->dev->bdev;
+	bio->bi_size = PAGE_SIZE;
+	bio->bi_next = NULL;
+	bio->bi_flags = 1 << BIO_UPTODATE;
+	bio->bi_comp_cpu = -1;
+	bio->bi_end_io = scrub_fixup_end_io;
+	bio->bi_private = &complete;
+
+	submit_bio(REQ_WRITE, bio);
+
+	wait_for_completion(&complete);
+
+	if (~bio->bi_flags & BIO_UPTODATE)
+		/* I/O-error, writeback failed, give up */
+		goto uncorrectable;
+
+	kfree(multi);
+	spin_lock(&sdev->stat_lock);
+	++sdev->stat.corrected_errors;
+	spin_unlock(&sdev->stat_lock);
+
+	if (printk_ratelimit())
+		printk(KERN_ERR "btrfs: fixed up at %lld\n", fixup->logical);
+	return;
+
+uncorrectable:
+	kfree(multi);
+	spin_lock(&sdev->stat_lock);
+	++sdev->stat.uncorrectable_errors;
+	spin_unlock(&sdev->stat_lock);
+
+	if (printk_ratelimit())
+		printk(KERN_ERR "btrfs: unable to fixup at %lld\n",
+			 fixup->logical);
+}
+
+static void scrub_bio_end_io(struct bio *bio, int err)
+{
+	struct scrub_bio *sbio = bio->bi_private;
+	struct scrub_dev *sdev = sbio->sdev;
+	struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
+
+	sbio->err = err;
+
+	SCRUB_QUEUE_WORK(fs_info->scrub_workers, &sbio->work);
+}
+
+static void scrub_checksum(scrub_work_t *work)
+{
+	struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
+	struct scrub_dev *sdev = sbio->sdev;
+	struct page *page;
+	void *buffer;
+	int i;
+	u64 flags;
+	u64 logical;
+	int ret;
+
+	if (sbio->err) {
+		for (i = 0; i < sbio->count; ++i) {
+			scrub_recheck_error(sbio, i);
+		}
+		spin_lock(&sdev->stat_lock);
+		++sdev->stat.read_errors;
+		spin_unlock(&sdev->stat_lock);
+		goto out;
+	}
+	for (i = 0; i < sbio->count; ++i) {
+		page = sbio->bio->bi_io_vec[i].bv_page;
+		buffer = kmap_atomic(page, KM_USER0);
+		flags = sbio->spag[i].flags;
+		logical = sbio->logical + i * PAGE_SIZE;
+		ret = 0;
+		if (flags & BTRFS_EXTENT_FLAG_DATA) {
+			ret = scrub_checksum_data(sdev, sbio->spag + i, buffer);
+		} else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+			ret = scrub_checksum_tree_block(sdev, sbio->spag + i,
+			                                logical, buffer);
+		} else if (flags & BTRFS_EXTENT_FLAG_SUPER) {
+			BUG_ON(i);
+			(void)scrub_checksum_super(sbio, buffer);
+		} else {
+			WARN_ON(1);
+		}
+		kunmap_atomic(buffer, KM_USER0);
+		if (ret)
+			scrub_recheck_error(sbio, i);
+	}
+
+out:
+	spin_lock(&sdev->list_lock);
+	sbio->next_free = sdev->first_free;
+	sdev->first_free = sbio->index;
+	spin_unlock(&sdev->list_lock);
+	atomic_dec(&sdev->in_flight);
+	wake_up(&sdev->list_wait);
+}
+
+static int scrub_checksum_data(struct scrub_dev *sdev,
+                               struct scrub_page *spag, void *buffer)
+{
+	u8 csum[BTRFS_CSUM_SIZE];
+	u32 crc = ~(u32)0;
+	int fail = 0;
+	struct btrfs_root *root = sdev->dev->dev_root;
+
+	if (!spag->have_csum)
+		return 0;
+
+	crc = btrfs_csum_data(root, buffer, crc, PAGE_SIZE);
+	btrfs_csum_final(crc, csum);
+	if (memcmp(csum, spag->csum, sdev->csum_size))
+		fail = 1;
+
+	spin_lock(&sdev->stat_lock);
+	++sdev->stat.data_extents_scrubbed;
+	sdev->stat.data_bytes_scrubbed += PAGE_SIZE;
+	if (fail)
+		++sdev->stat.csum_errors;
+	spin_unlock(&sdev->stat_lock);
+
+	return fail;
+}
+
+static int scrub_checksum_tree_block(struct scrub_dev *sdev,
+                                     struct scrub_page *spag, u64 logical,
+                                     void *buffer)
+{
+	struct btrfs_header *h;
+	struct btrfs_root *root = sdev->dev->dev_root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	u8 csum[BTRFS_CSUM_SIZE];
+	u32 crc = ~(u32)0;
+	int fail = 0;
+	int crc_fail = 0;
+
+	/*
+	 * we don't use the getter functions here, as we
+	 * a) don't have an extent buffer and
+	 * b) the page is already kmapped
+	 */
+	h = (struct btrfs_header *)buffer;
+
+	if (logical != le64_to_cpu(h->bytenr))
+		++fail;
+
+	if (spag->generation != le64_to_cpu(h->generation))
+		++fail;
+
+	if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
+		++fail;
+
+	if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
+	           BTRFS_UUID_SIZE))
+		++fail;
+
+	crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
+	                      PAGE_SIZE - BTRFS_CSUM_SIZE);
+	btrfs_csum_final(crc, csum);
+	if (memcmp(csum, h->csum, sdev->csum_size))
+		++crc_fail;
+
+	spin_lock(&sdev->stat_lock);
+	++sdev->stat.tree_extents_scrubbed;
+	sdev->stat.tree_bytes_scrubbed += PAGE_SIZE;
+	if (crc_fail)
+		++sdev->stat.csum_errors;
+	if (fail)
+		++sdev->stat.verify_errors;
+	spin_unlock(&sdev->stat_lock);
+
+	return (fail || crc_fail);
+}
+
+static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer)
+{
+	struct btrfs_super_block *s;
+	u64 logical;
+	struct scrub_dev *sdev = sbio->sdev;
+	struct btrfs_root *root = sdev->dev->dev_root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	u8 csum[BTRFS_CSUM_SIZE];
+	u32 crc = ~(u32)0;
+	int fail = 0;
+
+	s = (struct btrfs_super_block *)buffer;
+	logical = sbio->logical;
+
+	if (logical != le64_to_cpu(s->bytenr))
+		++fail;
+
+	if (sbio->spag[0].generation != le64_to_cpu(s->generation))
+		++fail;
+
+	if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
+		++fail;
+
+	crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
+	                      PAGE_SIZE - BTRFS_CSUM_SIZE);
+	btrfs_csum_final(crc, csum);
+	if (memcmp(csum, s->csum, sbio->sdev->csum_size))
+		++fail;
+
+	if (fail) {
+		/*
+		 * if we find an error in a super block, we just report it.
+		 * They will get written with the next transaction commit
+		 * anyway
+		 */
+		spin_lock(&sdev->stat_lock);
+		++sdev->stat.super_errors;
+		spin_unlock(&sdev->stat_lock);
+	}
+
+	return fail;
+}
+
+static int scrub_submit(struct scrub_dev *sdev)
+{
+	struct scrub_bio *sbio;
+
+	if (sdev->curr == -1)
+		return 0;
+
+	sbio = sdev->bios + sdev->curr;
+	
+	sbio->bio->bi_sector = sbio->physical >> 9;
+	sbio->bio->bi_size = sbio->count * PAGE_SIZE;
+	sbio->bio->bi_next = NULL;
+	sbio->bio->bi_flags = 1 << BIO_UPTODATE;
+	sbio->bio->bi_comp_cpu = -1;
+	sbio->bio->bi_bdev = sdev->dev->bdev;
+	sdev->curr = -1;
+	atomic_inc(&sdev->in_flight);
+
+	submit_bio(0, sbio->bio);
+
+	return 0;
+}
+
+static int scrub_page(struct scrub_dev *sdev, u64 logical, u64 len,
+                      u64 physical, u64 flags, u64 gen, u64 mirror_num,
+                      u8 *csum, int force)
+{
+	struct scrub_bio *sbio;
+again:
+	/*
+	 * grab a fresh bio or wait for one to become available
+	 */
+	while (sdev->curr == -1) {
+		unsigned long flags;
+		spin_lock_irqsave(&sdev->list_lock, flags);
+		sdev->curr = sdev->first_free;
+		if (sdev->curr != -1) {
+			sdev->first_free = sdev->bios[sdev->curr].next_free;
+			sdev->bios[sdev->curr].next_free = -1;
+			sdev->bios[sdev->curr].count = 0;
+			spin_unlock_irqrestore(&sdev->list_lock, flags);
+		} else {
+			spin_unlock_irqrestore(&sdev->list_lock, flags);
+			wait_event(sdev->list_wait, sdev->first_free != -1);
+		}
+	}
+	sbio = sdev->bios + sdev->curr;
+	if (sbio->count == 0) {
+		sbio->physical = physical;
+		sbio->logical = logical;
+	} else if (sbio->physical + sbio->count * PAGE_SIZE != physical) {
+		scrub_submit(sdev);
+		goto again;
+	}
+	sbio->spag[sbio->count].flags = flags;
+	sbio->spag[sbio->count].generation = gen;
+	sbio->spag[sbio->count].have_csum = 0;
+	sbio->spag[sbio->count].mirror_num = mirror_num;
+	if (csum) {
+		sbio->spag[sbio->count].have_csum = 1;
+		memcpy(sbio->spag[sbio->count].csum, csum, sdev->csum_size);
+	}
+	++sbio->count;
+	if (sbio->count == SCRUB_PAGES_PER_BIO || force)
+		scrub_submit(sdev);
+		
+	return 0;
+}
+
+static int scrub_find_csum(struct scrub_dev *sdev, u64 logical, u64 len,
+                           u8 *csum)
+{
+	struct btrfs_ordered_sum *sum = NULL;
+	int ret = 0;
+	unsigned long i;
+	unsigned long num_sectors;
+	u32 sectorsize = sdev->dev->dev_root->sectorsize;
+
+	while (!list_empty(&sdev->csum_list)) {
+		sum = list_first_entry(&sdev->csum_list,
+				       struct btrfs_ordered_sum, list);
+		if (sum->bytenr > logical)
+			return 0;
+		if (sum->bytenr + sum->len > logical)
+			break;
+
+		++sdev->stat.csum_discards;
+		list_del(&sum->list);
+		kfree(sum);
+		sum = NULL;
+	}
+	if (!sum)
+		return 0;
+
+	num_sectors = sum->len / sectorsize;
+	for (i = 0; i < num_sectors; ++i) {
+		if (sum->sums[i].bytenr == logical) {
+			memcpy(csum, &sum->sums[i].sum, sdev->csum_size);
+			ret = 1;
+			break;
+		}
+	}
+	if (ret && i == num_sectors - 1) {
+		list_del(&sum->list);
+		kfree(sum);
+	}
+	return ret;
+}
+
+/* scrub extent tries to collect up to 64 kB for each bio */
+static int scrub_extent(struct scrub_dev *sdev, u64 logical, u64 len,
+                        u64 physical, u64 flags, u64 gen, u64 mirror_num)
+{
+	int ret;
+	u8 csum[BTRFS_CSUM_SIZE];
+
+	while(len) {
+		u64 l = min_t(u64, len, PAGE_SIZE);
+		int have_csum = 0;
+
+		if (flags & BTRFS_EXTENT_FLAG_DATA) {
+			/* push csums to sbio */
+			have_csum = scrub_find_csum(sdev, logical, l, csum);
+			if (have_csum == 0)
+				++sdev->stat.no_csum;
+		}
+		ret = scrub_page(sdev, logical, l, physical, flags, gen,
+		                 mirror_num, have_csum ? csum : NULL, 0);
+		if (ret)
+			return ret;
+		len -= l;
+		logical += l;
+		physical += l;
+	}
+	return 0;
+}
+
+static noinline_for_stack int scrub_stripe(struct scrub_dev *sdev,
+	struct map_lookup *map, int num, u64 base, u64 length)
+{
+	struct btrfs_path *path;
+	struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
+	struct btrfs_root *root = fs_info->extent_root;
+	struct btrfs_root *csum_root = fs_info->csum_root;
+	struct btrfs_extent_item *extent;
+	u64 flags;
+	int ret;
+	int slot;
+	int i;
+	int nstripes;
+	int start_stripe;
+	struct extent_buffer *l;
+	struct btrfs_key key;
+	u64 physical;
+	u64 logical;
+	u64 generation;
+	u64 mirror_num;
+
+	u64 increment = map->stripe_len;
+	u64 offset;
+
+	nstripes = length;
+	offset = 0;
+	do_div(nstripes, map->stripe_len);
+	if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
+		offset = map->stripe_len * num;
+		increment = map->stripe_len * map->num_stripes;
+		mirror_num = 0;
+	} else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
+		int factor = map->num_stripes / map->sub_stripes;
+		offset = map->stripe_len * (num / map->sub_stripes);
+		increment = map->stripe_len * factor;
+		mirror_num = num % map->sub_stripes;
+	} else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
+		increment = map->stripe_len;
+		mirror_num = num % map->num_stripes;
+	} else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
+		increment = map->stripe_len;
+		mirror_num = num % map->num_stripes;
+	} else {
+		increment = map->stripe_len;
+		mirror_num = 0;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	path->reada = 2;
+	path->search_commit_root = 1;
+	path->skip_locking = 1;
+
+	/*
+	 * find all extents for each stripe and just read them to get
+	 * them into the page cache
+	 * FIXME: we can do better. build a more intelligent prefetching
+	 */
+	logical = base + offset;
+	physical = map->stripes[num].physical;
+	ret = 0;
+	for (i = 0; i < nstripes; ++i) {
+		key.objectid = logical;
+		key.type = BTRFS_EXTENT_ITEM_KEY;
+		key.offset = (u64)0;
+
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+
+		l = path->nodes[0];
+		slot = path->slots[0];
+		btrfs_item_key_to_cpu(l, &key, slot);
+		if (key.objectid != logical) {
+			ret = btrfs_previous_item(root, path, 0,
+			                          BTRFS_EXTENT_ITEM_KEY);
+			if (ret < 0)
+				goto out;
+		}
+
+		while (1) {
+			l = path->nodes[0];
+			slot = path->slots[0];
+			if (slot >= btrfs_header_nritems(l)) {
+				ret = btrfs_next_leaf(root, path);
+				if (ret == 0)
+					continue;
+				if (ret < 0)
+					goto out;
+
+				break;
+			}
+			btrfs_item_key_to_cpu(l, &key, slot);
+
+			if (key.objectid + key.offset <= logical)
+				goto next1;
+
+			if (key.objectid >= logical + map->stripe_len)
+				break;
+next1:
+			path->slots[0]++;
+		}
+		btrfs_release_path(root, path);
+		logical += increment;
+		physical += map->stripe_len;
+		cond_resched();
+	}
+
+	/*
+	 * collect all data csums for the stripe to avoid seeking during
+	 * the scrub. This might currently (crc32) end up to be about 1MB
+	 */
+	start_stripe = 0;
+again:
+	logical = base + offset + start_stripe * map->stripe_len;
+	physical = map->stripes[num].physical + start_stripe * map->stripe_len;
+	for (i = start_stripe; i < nstripes; ++i) {
+		ret = btrfs_lookup_csums_range(csum_root, logical,
+		                               logical + map->stripe_len - 1,
+		                               &sdev->csum_list, 1);
+		if (ret)
+			goto out;
+
+		logical += increment;
+		cond_resched();
+	}
+	/*
+	 * now find all extents for each stripe and scrub them
+	 */
+	logical = base + offset + start_stripe * map->stripe_len;
+	physical = map->stripes[num].physical + start_stripe * map->stripe_len;
+	ret = 0;
+	for (i = start_stripe; i < nstripes; ++i) {
+		/*
+		 * canceled?
+		 */
+		if (atomic_read(&fs_info->scrub_cancel_req) ||
+		    atomic_read(&sdev->cancel_req)) {
+			ret = -ECANCELED;
+			goto out;
+		}
+		/*
+		 * check to see if we have to pause
+		 */
+		if (atomic_read(&fs_info->scrub_pause_req)) {
+			/* push queued extents */
+			scrub_submit(sdev);
+			wait_event(sdev->list_wait,
+			           atomic_read(&sdev->in_flight) == 0);
+			atomic_inc(&fs_info->scrubs_paused);
+			wake_up(&fs_info->scrub_pause_wait);
+			mutex_lock(&fs_info->scrub_lock);
+			while(atomic_read(&fs_info->scrub_pause_req)) {
+				mutex_unlock(&fs_info->scrub_lock);
+				wait_event(fs_info->scrub_pause_wait,
+				   atomic_read(&fs_info->scrub_pause_req) == 0);
+				mutex_lock(&fs_info->scrub_lock);
+			}
+			atomic_dec(&fs_info->scrubs_paused);
+			mutex_unlock(&fs_info->scrub_lock);
+			wake_up(&fs_info->scrub_pause_wait);
+			scrub_free_csums(sdev);
+			goto again;
+		}
+
+		key.objectid = logical;
+		key.type = BTRFS_EXTENT_ITEM_KEY;
+		key.offset = (u64)0;
+
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+
+		l = path->nodes[0];
+		slot = path->slots[0];
+		btrfs_item_key_to_cpu(l, &key, slot);
+		if (key.objectid != logical) {
+			ret = btrfs_previous_item(root, path, 0,
+			                          BTRFS_EXTENT_ITEM_KEY);
+			if (ret < 0)
+				goto out;
+		}
+
+		while (1) {
+			l = path->nodes[0];
+			slot = path->slots[0];
+			if (slot >= btrfs_header_nritems(l)) {
+				ret = btrfs_next_leaf(root, path);
+				if (ret == 0)
+					continue;
+				if (ret < 0)
+					goto out;
+
+				break;
+			}
+			btrfs_item_key_to_cpu(l, &key, slot);
+
+			if (key.objectid + key.offset <= logical)
+				goto next;
+
+			if (key.objectid >= logical + map->stripe_len)
+				break;
+
+			if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY)
+				goto next;
+
+			extent = btrfs_item_ptr(l, slot,
+			                        struct btrfs_extent_item);
+			flags = btrfs_extent_flags(l, extent);
+			generation = btrfs_extent_generation(l, extent);
+
+			if (key.objectid < logical &&
+			    (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
+				printk(KERN_ERR
+				       "btrfs scrub: tree block %lld spanning "
+				       "stripes, ignored. logical=%lld\n",
+				       key.objectid, logical);
+				goto next;
+			}
+
+			/*
+			 * trim extent to this stripe
+			 */
+			if (key.objectid < logical) {
+				key.offset -= logical - key.objectid;
+				key.objectid = logical;
+			}
+			if (key.objectid + key.offset >
+			    logical + map->stripe_len) {
+				key.offset = logical + map->stripe_len -
+				             key.objectid;
+			}
+
+			ret = scrub_extent(sdev, key.objectid, key.offset,
+			                   key.objectid - logical + physical,
+			                   flags, generation, mirror_num);
+			if (ret)
+				goto out;
+next:
+			path->slots[0]++;
+		}
+		btrfs_release_path(root, path);
+		logical += increment;
+		physical += map->stripe_len;
+		spin_lock(&sdev->stat_lock);
+		sdev->stat.last_physical = physical;
+		spin_unlock(&sdev->stat_lock);
+	}
+	/* push queued extents */
+	scrub_submit(sdev);
+
+out:
+	btrfs_free_path(path);
+	return ret < 0 ? ret : 0;
+}
+
+static noinline_for_stack int scrub_chunk(struct scrub_dev *sdev, 
+	u64 chunk_tree, u64 chunk_objectid, u64 chunk_offset, u64 length)
+{
+	struct btrfs_mapping_tree *map_tree =
+		&sdev->dev->dev_root->fs_info->mapping_tree;
+	struct map_lookup *map;
+	struct extent_map *em;
+	int i;
+	int ret;
+
+	read_lock(&map_tree->map_tree.lock);
+	em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
+	read_unlock(&map_tree->map_tree.lock);
+
+	if (!em)
+		return -EINVAL;
+
+	map = (struct map_lookup *)em->bdev;
+	if (em->start != chunk_offset)
+		return -EINVAL;
+
+	if (em->len < length)
+		return -EINVAL;
+
+	for (i = 0; i < map->num_stripes; ++i) {
+		if (map->stripes[i].dev == sdev->dev) {
+			ret = scrub_stripe(sdev, map, i, chunk_offset, length);
+			if (ret)
+				return ret;
+		}
+	}
+	return 0;
+}
+
+static noinline_for_stack
+int scrub_enumerate_chunks(struct scrub_dev *sdev, u64 start, u64 end)
+{
+	struct btrfs_dev_extent *dev_extent = NULL;
+	struct btrfs_path *path;
+	struct btrfs_root *root = sdev->dev->dev_root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	u64 length;
+	u64 chunk_tree;
+	u64 chunk_objectid;
+	u64 chunk_offset;
+	int ret;
+	int slot;
+	struct extent_buffer *l;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	struct btrfs_block_group_cache *cache;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	path->reada = 2;
+	path->search_commit_root = 1;
+	path->skip_locking = 1;
+
+	key.objectid = sdev->dev->devid;
+	key.offset = 0ull;
+	key.type = BTRFS_DEV_EXTENT_KEY;
+
+
+	while (1) {
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+		ret = 0;
+
+		l = path->nodes[0];
+		slot = path->slots[0];
+
+		btrfs_item_key_to_cpu(l, &found_key, slot);
+
+		if (found_key.objectid != sdev->dev->devid)
+			break;
+
+		if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY)
+			break;
+
+		if (found_key.offset >= end)
+			break;
+
+		if (found_key.offset < key.offset)
+			break;
+
+		dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
+		length = btrfs_dev_extent_length(l, dev_extent);
+
+		if (found_key.offset + length <= start) {
+			key.offset = found_key.offset + length;
+			btrfs_release_path(root, path);
+			continue;
+		}
+
+		chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
+		chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
+		chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
+
+		/*
+		 * get a reference on the corresponding block group to prevent
+		 * the chunk from going away while we scrub it
+		 */
+		cache = btrfs_lookup_block_group(fs_info, chunk_offset);
+		if (!cache) {
+			ret = -ENOENT;
+			goto out;
+		}
+		ret = scrub_chunk(sdev, chunk_tree, chunk_objectid,
+		                  chunk_offset, length);
+		btrfs_put_block_group(cache);
+		if (ret)
+			break;
+
+		key.offset = found_key.offset + length;
+		btrfs_release_path(root, path);
+	}
+
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+static noinline_for_stack int scrub_supers(struct scrub_dev *sdev)
+{
+	int	i;
+	u64	bytenr;
+	u64	gen;
+	int	ret;
+	struct btrfs_device *device = sdev->dev;
+	struct btrfs_root *root = device->dev_root;
+
+	gen = root->fs_info->last_trans_committed;
+
+	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+		bytenr = btrfs_sb_offset(i);
+		if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
+			break;
+
+		ret = scrub_page(sdev, bytenr, PAGE_SIZE, bytenr, 
+		                 BTRFS_EXTENT_FLAG_SUPER, gen, i, NULL, 1);
+		if (ret)
+			return ret;
+	}
+	wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
+
+	return 0;
+}
+
+/*
+ * get a reference count on fs_info->scrub_workers. start worker if necessary
+ */
+static noinline_for_stack int scrub_workers_get(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	mutex_lock(&fs_info->scrub_lock);
+	if (fs_info->scrub_workers_refcnt == 0) {
+#ifdef SCRUB_BTRFS_WORKER
+		btrfs_start_workers(&fs_info->scrub_workers, 1);
+#else
+		fs_info->scrub_workers = create_workqueue("scrub");
+		if (!fs_info->scrub_workers) {
+			mutex_unlock(&fs_info->scrub_lock);
+			return -ENOMEM;
+		}
+#endif
+	}
+	++fs_info->scrub_workers_refcnt;
+	mutex_unlock(&fs_info->scrub_lock);
+
+	return 0;
+}
+
+static noinline_for_stack void scrub_workers_put(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	
+	mutex_lock(&fs_info->scrub_lock);
+	if (--fs_info->scrub_workers_refcnt == 0) {
+#ifdef SCRUB_BTRFS_WORKER
+		btrfs_stop_workers(&fs_info->scrub_workers);
+#else
+		destroy_workqueue(fs_info->scrub_workers);
+		fs_info->scrub_workers = NULL;
+#endif
+
+	}
+	WARN_ON(fs_info->scrub_workers_refcnt < 0);
+	mutex_unlock(&fs_info->scrub_lock);
+}
+
+
+int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
+                    struct btrfs_scrub_progress *progress)
+{
+	struct scrub_dev *sdev;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int ret;
+	struct btrfs_device *dev;
+
+	if (root->fs_info->closing)
+		return -EINVAL;
+
+	/*
+	 * check some assumptions
+	 */
+	if (root->sectorsize != PAGE_SIZE ||
+	    root->sectorsize != root->leafsize ||
+	    root->sectorsize != root->nodesize) {
+		printk(KERN_ERR "btrfs_scrub: size assumptions fail\n");
+		return -EINVAL;
+	}
+	    
+	ret = scrub_workers_get(root);
+	if (ret)
+		return ret;
+
+	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
+	dev = btrfs_find_device(root, devid, NULL, NULL);
+	if (!dev || dev->missing) {
+		mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
+		scrub_workers_put(root);
+		return -ENODEV;
+	}
+
+	mutex_lock(&fs_info->scrub_lock);
+	if (dev->scrub_device) {
+		mutex_unlock(&fs_info->scrub_lock);
+		scrub_workers_put(root);
+		return -EINPROGRESS;
+	}
+	sdev = scrub_setup_dev(dev);
+	if (IS_ERR(sdev)) {
+		mutex_unlock(&fs_info->scrub_lock);
+		scrub_workers_put(root);
+		return PTR_ERR(sdev);
+	}
+	dev->scrub_device = sdev;
+
+	atomic_inc(&fs_info->scrubs_running);
+	mutex_unlock(&fs_info->scrub_lock);
+	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
+
+	down_read(&fs_info->scrub_super_lock);
+	ret = scrub_supers(sdev);
+	up_read(&fs_info->scrub_super_lock);
+
+	if (!ret)
+		ret = scrub_enumerate_chunks(sdev, start, end);
+
+	wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
+
+	mutex_lock(&fs_info->scrub_lock);
+	atomic_dec(&fs_info->scrubs_running);
+	mutex_unlock(&fs_info->scrub_lock);
+	wake_up(&fs_info->scrub_pause_wait);
+
+	if (progress)
+		memcpy(progress, &sdev->stat, sizeof(*progress));
+
+	mutex_lock(&fs_info->scrub_lock);
+	dev->scrub_device = NULL;
+	mutex_unlock(&fs_info->scrub_lock);
+
+	scrub_free_dev(sdev);
+	scrub_workers_put(root);
+
+	return ret;
+}
+
+int btrfs_scrub_pause(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	mutex_lock(&fs_info->scrub_lock);
+	atomic_inc(&fs_info->scrub_pause_req);
+	while (atomic_read(&fs_info->scrubs_paused) !=
+	       atomic_read(&fs_info->scrubs_running)) {
+		mutex_unlock(&fs_info->scrub_lock);
+		wait_event(fs_info->scrub_pause_wait,
+			   atomic_read(&fs_info->scrubs_paused) ==
+			   atomic_read(&fs_info->scrubs_running));
+		mutex_lock(&fs_info->scrub_lock);
+	}
+	mutex_unlock(&fs_info->scrub_lock);
+
+	return 0;
+}
+
+int btrfs_scrub_continue(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	atomic_dec(&fs_info->scrub_pause_req);
+	wake_up(&fs_info->scrub_pause_wait);
+	return 0;
+}
+
+int btrfs_scrub_pause_super(struct btrfs_root *root)
+{
+	down_write(&root->fs_info->scrub_super_lock);
+	return 0;
+}
+
+int btrfs_scrub_continue_super(struct btrfs_root *root)
+{
+	up_write(&root->fs_info->scrub_super_lock);
+	return 0;
+}
+
+int btrfs_scrub_cancel(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	mutex_lock(&fs_info->scrub_lock);
+	if (!atomic_read(&fs_info->scrubs_running)) {
+		mutex_unlock(&fs_info->scrub_lock);
+		return -ENOTCONN;
+	}
+
+	atomic_inc(&fs_info->scrub_cancel_req);
+	while(atomic_read(&fs_info->scrubs_running)) {
+		mutex_unlock(&fs_info->scrub_lock);
+		wait_event(fs_info->scrub_pause_wait,
+			   atomic_read(&fs_info->scrubs_running) == 0);
+		mutex_lock(&fs_info->scrub_lock);
+	}
+	atomic_dec(&fs_info->scrub_cancel_req);
+	mutex_unlock(&fs_info->scrub_lock);
+	
+	return 0;
+}
+
+int btrfs_scrub_cancel_dev(struct btrfs_root *root, struct btrfs_device *dev)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct scrub_dev *sdev;
+
+	mutex_lock(&fs_info->scrub_lock);
+	sdev = dev->scrub_device;
+	if (!sdev) {
+		mutex_unlock(&fs_info->scrub_lock);
+		return -ENOTCONN;
+	}
+	atomic_inc(&sdev->cancel_req);
+	while(dev->scrub_device) {
+		mutex_unlock(&fs_info->scrub_lock);
+		wait_event(fs_info->scrub_pause_wait,
+		           dev->scrub_device == NULL);
+		mutex_lock(&fs_info->scrub_lock);
+	}
+	mutex_unlock(&fs_info->scrub_lock);
+		
+	return 0;
+}
+int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_device *dev;
+	int ret;
+
+	/*
+	 * we have to hold the device_list_mutex here so the device
+	 * does not go away in cancel_dev. FIXME: find a better solution
+	 */
+	mutex_lock(&fs_info->fs_devices->device_list_mutex);
+	dev = btrfs_find_device(root, devid, NULL, NULL);
+	if (!dev) {
+		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
+		return -ENODEV;
+	}
+	ret = btrfs_scrub_cancel_dev(root, dev);
+	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
+
+	return ret;
+}
+	
+int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
+                         struct btrfs_scrub_progress *progress)
+{
+	struct btrfs_device *dev;
+	struct scrub_dev *sdev = NULL;
+
+	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
+	dev = btrfs_find_device(root, devid, NULL, NULL);
+	if (dev)
+		sdev = dev->scrub_device;
+	if (sdev)
+		memcpy(progress, &sdev->stat, sizeof(*progress));
+	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
+
+	return dev ? (sdev ? 0 : -ENOTCONN) : -ENODEV;
+}
-- 
1.7.3.4

[PATCH v1 5/6] btrfs: sync scrub with commit & device removal

[Arne Jansen]

This adds several synchronizations:
 - for a transaction commit, the scrub gets paused before the
   tree roots are committed until the super are safely on disk
 - during a log commit, scrubbing of supers is disabled
 - on unmount, the scrub gets cancelled
 - on device removal, the scrub for the particular device gets cancelled

Signed-off-by: Arne Jansen <sensille@gmx.net>
---
 fs/btrfs/disk-io.c     |    1 +
 fs/btrfs/transaction.c |    3 +++
 fs/btrfs/tree-log.c    |    2 ++
 fs/btrfs/volumes.c     |    2 ++
 4 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 061a48a..4d62bc3 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2508,6 +2508,7 @@ int close_ctree(struct btrfs_root *root)
 	fs_info->closing = 1;
 	smp_mb();
 
+	btrfs_scrub_cancel(root);
 	btrfs_put_block_group_cache(fs_info);
 
 	/*
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 3d73c8d..5a43b20 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1310,6 +1310,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
 	WARN_ON(cur_trans != trans->transaction);
 
+	btrfs_scrub_pause(root);
 	/* btrfs_commit_tree_roots is responsible for getting the
 	 * various roots consistent with each other.  Every pointer
 	 * in the tree of tree roots has to point to the most up to date
@@ -1391,6 +1392,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
 	mutex_unlock(&root->fs_info->trans_mutex);
 
+	btrfs_scrub_continue(root);
+
 	if (current->journal_info == trans)
 		current->journal_info = NULL;
 
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 1f6788f..2be84fa 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2098,7 +2098,9 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 	 * the running transaction open, so a full commit can't hop
 	 * in and cause problems either.
 	 */
+	btrfs_scrub_pause_super(root);
 	write_ctree_super(trans, root->fs_info->tree_root, 1);
+	btrfs_scrub_continue_super(root);
 	ret = 0;
 
 	mutex_lock(&root->log_mutex);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index acd7930..029baea0 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1330,6 +1330,8 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 		goto error_brelse;
 
 	device->in_fs_metadata = 0;
+	smp_mb();
+	btrfs_scrub_cancel_dev(root, device);
 
 	/*
 	 * the device list mutex makes sure that we don't change
-- 
1.7.3.4

[PATCH v1 6/6] btrfs: new ioctls for scrub

[Arne Jansen]

adds ioctls necessary to start and cancel scrubs, to get current
progress and to get info about devices to be scrubbed.
Note that the scrub is done per-device and that the ioctl only
returns after the scrub for this devices is finished or has been
canceled.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
---
 fs/btrfs/ioctl.c |   85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/ioctl.h |    7 ++++
 2 files changed, 92 insertions(+), 0 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index be2d4f6..f988ab6 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1715,6 +1715,31 @@ static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
 	return ret;
 }
 
+static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
+{
+	struct btrfs_ioctl_dev_info_args di_args;
+	struct btrfs_device *device, *next;
+	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	di_args.num_devices = fs_devices->num_devices;
+	di_args.max_id = 0;
+
+	mutex_lock(&fs_devices->device_list_mutex);
+	list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
+		if (device->devid > di_args.max_id)
+			di_args.max_id = device->devid;
+	}
+	mutex_unlock(&fs_devices->device_list_mutex);
+
+	if (copy_to_user(arg, &di_args, sizeof(di_args)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 				       u64 off, u64 olen, u64 destoff)
 {
@@ -2372,6 +2397,58 @@ static noinline long btrfs_ioctl_wait_sync(struct file *file, void __user *argp)
 	return btrfs_wait_for_commit(root, transid);
 }
 
+static long btrfs_ioctl_scrub(struct btrfs_root *root, void __user *arg)
+{
+	int ret;
+	struct btrfs_ioctl_scrub_args *sa;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa))
+		return PTR_ERR(sa);
+
+	ret = btrfs_scrub_dev(root, sa->devid, sa->start, sa->end,
+	                      &sa->progress);
+
+	if (copy_to_user(arg, sa, sizeof(*sa)))
+		ret = -EFAULT;
+
+	kfree(sa);
+	return ret;
+}
+
+static long btrfs_ioctl_scrub_cancel(struct btrfs_root *root, void __user *arg)
+{
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	return btrfs_scrub_cancel(root);
+}
+
+static long btrfs_ioctl_scrub_progress(struct btrfs_root *root,
+                                       void __user *arg)
+{
+	struct btrfs_ioctl_scrub_args *sa;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa))
+		return PTR_ERR(sa);
+
+	ret = btrfs_scrub_progress(root, sa->devid, &sa->progress);
+
+	if (copy_to_user(arg, sa, sizeof(*sa)))
+		ret = -EFAULT;
+
+	kfree(sa);
+	return ret;
+}
+
 long btrfs_ioctl(struct file *file, unsigned int
 		cmd, unsigned long arg)
 {
@@ -2409,6 +2486,8 @@ long btrfs_ioctl(struct file *file, unsigned int
 		return btrfs_ioctl_add_dev(root, argp);
 	case BTRFS_IOC_RM_DEV:
 		return btrfs_ioctl_rm_dev(root, argp);
+	case BTRFS_IOC_DEV_INFO:
+		return btrfs_ioctl_dev_info(root, argp);
 	case BTRFS_IOC_BALANCE:
 		return btrfs_balance(root->fs_info->dev_root);
 	case BTRFS_IOC_CLONE:
@@ -2432,6 +2511,12 @@ long btrfs_ioctl(struct file *file, unsigned int
 		return btrfs_ioctl_start_sync(file, argp);
 	case BTRFS_IOC_WAIT_SYNC:
 		return btrfs_ioctl_wait_sync(file, argp);
+	case BTRFS_IOC_SCRUB:
+		return btrfs_ioctl_scrub(root, argp);
+	case BTRFS_IOC_SCRUB_CANCEL:
+		return btrfs_ioctl_scrub_cancel(root, argp);
+	case BTRFS_IOC_SCRUB_PROGRESS:
+		return btrfs_ioctl_scrub_progress(root, argp);
 	}
 
 	return -ENOTTY;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index f7bf177..9aa3603 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -232,4 +232,11 @@ struct btrfs_ioctl_space_args {
 				   struct btrfs_ioctl_vol_args_v2)
 #define BTRFS_IOC_SUBVOL_GETFLAGS _IOW(BTRFS_IOCTL_MAGIC, 25, __u64)
 #define BTRFS_IOC_SUBVOL_SETFLAGS _IOW(BTRFS_IOCTL_MAGIC, 26, __u64)
+#define BTRFS_IOC_SCRUB _IOWR(BTRFS_IOCTL_MAGIC, 27, \
+                             struct btrfs_ioctl_scrub_args)
+#define BTRFS_IOC_SCRUB_CANCEL _IO(BTRFS_IOCTL_MAGIC, 28)
+#define BTRFS_IOC_SCRUB_PROGRESS _IOWR(BTRFS_IOCTL_MAGIC, 29, \
+                             struct btrfs_ioctl_scrub_args)
+#define BTRFS_IOC_DEV_INFO _IOR(BTRFS_IOCTL_MAGIC, 30, \
+                                struct btrfs_ioctl_dev_info_args)
 #endif
-- 
1.7.3.4