From: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
To: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>,
linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: [PATCH 16/17] ext4: Support for synchronous DAX faults
Date: Tue, 24 Oct 2017 17:24:13 +0200 [thread overview]
Message-ID: <20171024152415.22864-17-jack@suse.cz> (raw)
In-Reply-To: <20171024152415.22864-1-jack-AlSwsSmVLrQ@public.gmane.org>
We return IOMAP_F_DIRTY flag from ext4_iomap_begin() when asked to
prepare blocks for writing and the inode has some uncommitted metadata
changes. In the fault handler ext4_dax_fault() we then detect this case
(through VM_FAULT_NEEDDSYNC return value) and call helper
dax_finish_sync_fault() to flush metadata changes and insert page table
entry. Note that this will also dirty corresponding radix tree entry
which is what we want - fsync(2) will still provide data integrity
guarantees for applications not using userspace flushing. And
applications using userspace flushing can avoid calling fsync(2) and
thus avoid the performance overhead.
Reviewed-by: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Signed-off-by: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
---
fs/ext4/file.c | 15 ++++++++++++++-
fs/ext4/inode.c | 15 +++++++++++++++
fs/jbd2/journal.c | 17 +++++++++++++++++
include/linux/jbd2.h | 1 +
4 files changed, 47 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 208adfc3e673..08a1d1a33a90 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -26,6 +26,7 @@
#include <linux/quotaops.h>
#include <linux/pagevec.h>
#include <linux/uio.h>
+#include <linux/mman.h>
#include "ext4.h"
#include "ext4_jbd2.h"
#include "xattr.h"
@@ -295,6 +296,7 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf,
*/
bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
(vmf->vma->vm_flags & VM_SHARED);
+ pfn_t pfn;
if (write) {
sb_start_pagefault(sb);
@@ -310,9 +312,12 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf,
} else {
down_read(&EXT4_I(inode)->i_mmap_sem);
}
- result = dax_iomap_fault(vmf, pe_size, NULL, &ext4_iomap_ops);
+ result = dax_iomap_fault(vmf, pe_size, &pfn, &ext4_iomap_ops);
if (write) {
ext4_journal_stop(handle);
+ /* Handling synchronous page fault? */
+ if (result & VM_FAULT_NEEDDSYNC)
+ result = dax_finish_sync_fault(vmf, pe_size, pfn);
up_read(&EXT4_I(inode)->i_mmap_sem);
sb_end_pagefault(sb);
} else {
@@ -350,6 +355,13 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
return -EIO;
+ /*
+ * We don't support synchronous mappings for non-DAX files. At least
+ * until someone comes with a sensible use case.
+ */
+ if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC))
+ return -EOPNOTSUPP;
+
file_accessed(file);
if (IS_DAX(file_inode(file))) {
vma->vm_ops = &ext4_dax_vm_ops;
@@ -719,6 +731,7 @@ const struct file_operations ext4_file_operations = {
.compat_ioctl = ext4_compat_ioctl,
#endif
.mmap = ext4_file_mmap,
+ .mmap_supported_flags = MAP_SYNC,
.open = ext4_file_open,
.release = ext4_release_file,
.fsync = ext4_sync_file,
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 31db875bc7a1..13a198924a0f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3394,6 +3394,19 @@ static int ext4_releasepage(struct page *page, gfp_t wait)
}
#ifdef CONFIG_FS_DAX
+static bool ext4_inode_datasync_dirty(struct inode *inode)
+{
+ journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
+
+ if (journal)
+ return !jbd2_transaction_committed(journal,
+ EXT4_I(inode)->i_datasync_tid);
+ /* Any metadata buffers to write? */
+ if (!list_empty(&inode->i_mapping->private_list))
+ return true;
+ return inode->i_state & I_DIRTY_DATASYNC;
+}
+
static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
unsigned flags, struct iomap *iomap)
{
@@ -3466,6 +3479,8 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
}
iomap->flags = 0;
+ if ((flags & IOMAP_WRITE) && ext4_inode_datasync_dirty(inode))
+ iomap->flags |= IOMAP_F_DIRTY;
iomap->bdev = inode->i_sb->s_bdev;
iomap->dax_dev = sbi->s_daxdev;
iomap->offset = first_block << blkbits;
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 7d5ef3bf3f3e..fa8cde498b4b 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -738,6 +738,23 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
return err;
}
+/* Return 1 when transaction with given tid has already committed. */
+int jbd2_transaction_committed(journal_t *journal, tid_t tid)
+{
+ int ret = 1;
+
+ read_lock(&journal->j_state_lock);
+ if (journal->j_running_transaction &&
+ journal->j_running_transaction->t_tid == tid)
+ ret = 0;
+ if (journal->j_committing_transaction &&
+ journal->j_committing_transaction->t_tid == tid)
+ ret = 0;
+ read_unlock(&journal->j_state_lock);
+ return ret;
+}
+EXPORT_SYMBOL(jbd2_transaction_committed);
+
/*
* When this function returns the transaction corresponding to tid
* will be completed. If the transaction has currently running, start
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 606b6bce3a5b..296d1e0ea87b 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1367,6 +1367,7 @@ int jbd2_log_start_commit(journal_t *journal, tid_t tid);
int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
+int jbd2_transaction_committed(journal_t *journal, tid_t tid);
int jbd2_complete_transaction(journal_t *journal, tid_t tid);
int jbd2_log_do_checkpoint(journal_t *journal);
int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
--
2.12.3
next prev parent reply other threads:[~2017-10-24 15:24 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-24 15:23 [PATCH 0/17 v5] dax, ext4, xfs: Synchronous page faults Jan Kara
[not found] ` <20171024152415.22864-1-jack-AlSwsSmVLrQ@public.gmane.org>
2017-10-24 15:23 ` [PATCH 01/17] mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags Jan Kara
[not found] ` <20171024152415.22864-2-jack-AlSwsSmVLrQ@public.gmane.org>
2017-10-24 21:21 ` Ross Zwisler
2017-10-24 15:23 ` [PATCH 02/17] mm: Remove VM_FAULT_HWPOISON_LARGE_MASK Jan Kara
2017-10-24 15:24 ` [PATCH 03/17] dax: Simplify arguments of dax_insert_mapping() Jan Kara
2017-10-24 15:24 ` [PATCH 05/17] dax: Create local variable for VMA in dax_iomap_pte_fault() Jan Kara
2017-10-24 15:24 ` [PATCH 06/17] dax: Create local variable for vmf->flags & FAULT_FLAG_WRITE test Jan Kara
2017-10-24 15:24 ` [PATCH 07/17] dax: Inline dax_insert_mapping() into the callsite Jan Kara
2017-10-24 15:24 ` [PATCH 08/17] dax: Inline dax_pmd_insert_mapping() " Jan Kara
2017-10-24 15:24 ` [PATCH 09/17] dax: Fix comment describing dax_iomap_fault() Jan Kara
2017-10-24 15:24 ` [PATCH 10/17] dax: Allow dax_iomap_fault() to return pfn Jan Kara
2017-10-24 15:24 ` [PATCH 12/17] mm: Define MAP_SYNC and VM_SYNC flags Jan Kara
2017-10-24 15:24 ` [PATCH 13/17] dax, iomap: Add support for synchronous faults Jan Kara
2017-10-24 15:24 ` [PATCH 15/17] ext4: Simplify error handling in ext4_dax_huge_fault() Jan Kara
2017-10-24 15:24 ` Jan Kara [this message]
2017-10-24 15:24 ` [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and MAP_SYNC Jan Kara
2017-10-24 21:10 ` Ross Zwisler
2017-10-26 13:24 ` Jan Kara
[not found] ` <20171026132402.GB31161-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2017-10-26 18:22 ` Ross Zwisler
2017-10-24 15:24 ` [PATCH 04/17] dax: Factor out getting of pfn out of iomap Jan Kara
2017-10-24 15:24 ` [PATCH 11/17] dax: Allow tuning whether dax_insert_mapping_entry() dirties entry Jan Kara
2017-10-24 15:24 ` [PATCH 14/17] dax: Implement dax_finish_sync_fault() Jan Kara
2017-10-24 15:24 ` [PATCH 17/17] xfs: support for synchronous DAX faults Jan Kara
2017-10-24 21:29 ` Ross Zwisler
2017-10-24 22:23 ` Dave Chinner
2017-10-26 15:48 ` Jan Kara
[not found] ` <20171026154804.GF31161-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2017-10-26 21:16 ` Dave Chinner
2017-10-27 10:08 ` Jan Kara
[not found] ` <20171027100834.GH31161-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2017-10-31 15:19 ` Jan Kara
[not found] ` <20171031151907.GB26128-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2017-10-31 21:50 ` Dan Williams
[not found] ` <CAPcyv4gBVyZ8KhB2s1M0BdhC1=HAean6Mb6oV7zsJBx0-t3bhw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-11-01 3:47 ` Ross Zwisler
2017-10-27 6:43 ` Christoph Hellwig
[not found] ` <20171027064301.GC22931-jcswGhMUV9g@public.gmane.org>
2017-10-27 9:13 ` Jan Kara
-- strict thread matches above, loose matches on Subject: below --
2017-10-19 12:57 [PATCH 0/17 v4] dax, ext4, xfs: Synchronous page faults Jan Kara
[not found] ` <20171019125817.11580-1-jack-AlSwsSmVLrQ@public.gmane.org>
2017-10-19 12:58 ` [PATCH 16/17] ext4: Support for synchronous DAX faults Jan Kara
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