[PATCH] xfs: convert COW blocks to real blocks before unwritten extent conversion

[PATCH] xfs: convert COW blocks to real blocks before unwritten extent conversion

[Christoph Hellwig]

We need to splice COW blocks we've completed in xfs_end_io_direct_write
into the data fork before converting unwritten extents.  Otherwise
xfs_bmapi_write might first allocate blocks for any holes in the data
fork, which isn't only not needed but also harmful as it might cause
reserved block underruns in the transaction.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_aops.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 0e2a931..3e57a56 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1547,13 +1547,13 @@ xfs_end_io_direct_write(
 		i_size_write(inode, offset + size);
 	spin_unlock(&ip->i_flags_lock);
 
+	if (flags & XFS_DIO_FLAG_COW)
+		error = xfs_reflink_end_cow(ip, offset, size);
 	if (flags & XFS_DIO_FLAG_UNWRITTEN) {
 		trace_xfs_end_io_direct_write_unwritten(ip, offset, size);
 
 		error = xfs_iomap_write_unwritten(ip, offset, size);
 	}
-	if (flags & XFS_DIO_FLAG_COW)
-		error = xfs_reflink_end_cow(ip, offset, size);
 	if (flags & XFS_DIO_FLAG_APPEND) {
 		trace_xfs_end_io_direct_write_append(ip, offset, size);
 
-- 
2.10.1.382.ga23ca1b

Re: [PATCH] xfs: convert COW blocks to real blocks before unwritten extent conversion

[Dave Chinner]

On Mon, Oct 10, 2016 at 03:06:34PM +0200, Christoph Hellwig wrote:
> We need to splice COW blocks we've completed in xfs_end_io_direct_write
> into the data fork before converting unwritten extents.  Otherwise
> xfs_bmapi_write might first allocate blocks for any holes in the data
> fork, which isn't only not needed but also harmful as it might cause
> reserved block underruns in the transaction.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Committed and pushe dout to the for-next branch (commit
feac470e3642e8956ac9b7f14224e6b301b9219d). If there's no more
late-breaking, urgent fixes, then this is what I'll ask Linus to
pull tomorrow....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

Re: [PATCH] xfs: convert COW blocks to real blocks before unwritten extent conversion

[Darrick J. Wong]

On Tue, Oct 11, 2016 at 06:38:25PM +1100, Dave Chinner wrote:
> On Mon, Oct 10, 2016 at 03:06:34PM +0200, Christoph Hellwig wrote:
> > We need to splice COW blocks we've completed in xfs_end_io_direct_write
> > into the data fork before converting unwritten extents.  Otherwise
> > xfs_bmapi_write might first allocate blocks for any holes in the data
> > fork, which isn't only not needed but also harmful as it might cause
> > reserved block underruns in the transaction.
> > 
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Committed and pushe dout to the for-next branch (commit
> feac470e3642e8956ac9b7f14224e6b301b9219d). If there's no more
> late-breaking, urgent fixes, then this is what I'll ask Linus to
> pull tomorrow....

Everything looks ok from here!

--D

> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com
> --
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