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fs: Fix missed inode writeback when racing with __writeback_single_inode

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When mmb_fsync_noflush() or simple_fsync_noflush() race with another
writeback of the same inode, they can see inode dirty bits are already
clear and skip inode writeback although the racing
__writeback_single_inode() didn't yet get to writing anything. This can
result in fsync(2) returning without properly persisting the inode.

We already have I_SYNC bit for this synchronization and
writeback_single_inode() properly uses it so just fix
mmb_fsync_noflush() and simple_fsync_noflush() to take it into account
as well.

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260727104923.3828017-23-jack@suse.cz
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This commit is contained in:
Jan Kara
2026-07-27 12:49:21 +02:00
committed by Christian Brauner
parent b0bca4e95b
commit 5a499dad2c
2 changed files with 6 additions and 4 deletions
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5
fs/buffer.c
View File

@@ -655,9 +655,10 @@ int mmb_fsync_noflush(struct file *file, struct mapping_metadata_bhs *mmb,
if (mmb)
ret = mmb_sync(mmb);
if (!(inode_state_read_once(inode) & I_DIRTY_ALL))
if (!(inode_state_read_once(inode) & (I_DIRTY_ALL | I_SYNC)))
goto out;
if (datasync && !(inode_state_read_once(inode) & I_DIRTY_DATASYNC))
if (datasync &&
!(inode_state_read_once(inode) & (I_DIRTY_DATASYNC | I_SYNC)))
goto out;
err = sync_inode_metadata(inode, 1);

5
fs/libfs.c
View File

@@ -1559,9 +1559,10 @@ int simple_fsync_noflush(struct file *file, loff_t start, loff_t end,
if (err)
return err;
if (!(inode_state_read_once(inode) & I_DIRTY_ALL))
if (!(inode_state_read_once(inode) & (I_DIRTY_ALL | I_SYNC)))
goto out;
if (datasync && !(inode_state_read_once(inode) & I_DIRTY_DATASYNC))
if (datasync &&
!(inode_state_read_once(inode) & (I_DIRTY_DATASYNC | I_SYNC)))
goto out;
ret = sync_inode_metadata(inode, 1);