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author | Christoph Hellwig <hch@lst.de> | 2017-02-07 00:00:54 +0300 |
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committer | Darrick J. Wong <darrick.wong@oracle.com> | 2017-02-07 04:47:46 +0300 |
commit | 54a4ef8af4e0dc5c983d17fcb9cf5fd25666d94e (patch) | |
tree | 47f55c2f61169e2774cd73770c2237ff9356a5ec /fs/xfs/xfs_reflink.c | |
parent | 4dd2eb633598cb6a5a0be2fd9a2be0819f5eeb5f (diff) | |
download | linux-54a4ef8af4e0dc5c983d17fcb9cf5fd25666d94e.tar.xz |
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_reflink.c')
0 files changed, 0 insertions, 0 deletions