summaryrefslogtreecommitdiffstats
path: root/fs/xfs/xfs_file.c
diff options
context:
space:
mode:
authorChristoph Hellwig <hch@lst.de>2017-02-06 13:00:54 -0800
committerDarrick J. Wong <darrick.wong@oracle.com>2017-02-06 17:47:46 -0800
commit54a4ef8af4e0dc5c983d17fcb9cf5fd25666d94e (patch)
tree47f55c2f61169e2774cd73770c2237ff9356a5ec /fs/xfs/xfs_file.c
parent4dd2eb633598cb6a5a0be2fd9a2be0819f5eeb5f (diff)
downloadlinux-54a4ef8af4e0dc5c983d17fcb9cf5fd25666d94e.tar.gz
linux-54a4ef8af4e0dc5c983d17fcb9cf5fd25666d94e.tar.bz2
linux-54a4ef8af4e0dc5c983d17fcb9cf5fd25666d94e.zip
xfs: reject all unaligned direct writes to reflinked files
We currently fall back from direct to buffered writes if we detect a remaining shared extent in the iomap_begin callback. But by the time iomap_begin is called for the potentially unaligned end block we might have already written most of the data to disk, which we'd now write again using buffered I/O. To avoid this reject all writes to reflinked files before starting I/O so that we are guaranteed to only write the data once. The alternative would be to unshare the unaligned start and/or end block before doing the I/O. I think that's doable, and will actually be required to support reflinks on DAX file system. But it will take a little more time and I'd rather get rid of the double write ASAP. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/xfs/xfs_file.c')
-rw-r--r--fs/xfs/xfs_file.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 032c8a74824a..2a695a8f4fe7 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -527,6 +527,15 @@ xfs_file_dio_aio_write(
if ((iocb->ki_pos & mp->m_blockmask) ||
((iocb->ki_pos + count) & mp->m_blockmask)) {
unaligned_io = 1;
+
+ /*
+ * We can't properly handle unaligned direct I/O to reflink
+ * files yet, as we can't unshare a partial block.
+ */
+ if (xfs_is_reflink_inode(ip)) {
+ trace_xfs_reflink_bounce_dio_write(ip, iocb->ki_pos, count);
+ return -EREMCHG;
+ }
iolock = XFS_IOLOCK_EXCL;
} else {
iolock = XFS_IOLOCK_SHARED;