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Revert "ext4: use ext4_write_inode() when fsyncing w/o a journal" 

This reverts commit ad211f3e94.

As Jan Kara pointed out, this change was unsafe since it means we lose
the call to sync_mapping_buffers() in the nojournal case.  The
original point of the commit was avoid taking the inode mutex (since
it causes a lockdep warning in generic/113); but we need the mutex in
order to call sync_mapping_buffers().

The real fix to this problem was discussed here:

https://lore.kernel.org/lkml/20181025150540.259281-4-bvanassche@acm.org

The proposed patch was to fix a syzbot complaint, but the problem can
also demonstrated via "kvm-xfstests -c nojournal generic/113".
Multiple solutions were discused in the e-mail thread, but none have
landed in the kernel as of this writing.  Anyway, commit
ad211f3e94 is absolutely the wrong way to suppress the lockdep, so
revert it.

Fixes: ad211f3e94 ("ext4: use ext4_write_inode() when fsyncing w/o a journal")
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reported: Jan Kara <jack@suse.cz>
This commit is contained in:
Theodore Ts'o 2019-01-31 23:41:11 -05:00
parent 49a57857ae
commit 8fdd60f2ae
1 changed files with 4 additions and 9 deletions
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13
fs/ext4/fsync.c
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@ -116,16 +116,8 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
goto out;
}
ret = file_write_and_wait_range(file, start, end);
if (ret)
return ret;
if (!journal) {
struct writeback_control wbc = {
.sync_mode = WB_SYNC_ALL
};
ret = ext4_write_inode(inode, &wbc);
ret = __generic_file_fsync(file, start, end, datasync);
if (!ret)
ret = ext4_sync_parent(inode);
if (test_opt(inode->i_sb, BARRIER))
@ -133,6 +125,9 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
goto out;
}
ret = file_write_and_wait_range(file, start, end);
if (ret)
return ret;
/*
* data=writeback,ordered:
* The caller's filemap_fdatawrite()/wait will sync the data.