diff options
author | Christoph Hellwig <hch@lst.de> | 2017-02-06 13:00:54 -0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-04-08 09:30:31 +0200 |
commit | 5bbf5ba693ac6dc323d6608740311c34b978e986 (patch) | |
tree | aec12255bff806d5f96e89728df838419f695d3c /fs/xfs/xfs_aops.c | |
parent | 67eb7bf836af69b967ab437c6c84e81c4351b957 (diff) |
xfs: reject all unaligned direct writes to reflinked files
commit 54a4ef8af4e0dc5c983d17fcb9cf5fd25666d94e upstream.
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>
[slight changes in context due to the new direct I/O code in 4.10+]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/xfs/xfs_aops.c')
-rw-r--r-- | fs/xfs/xfs_aops.c | 45 |
1 files changed, 0 insertions, 45 deletions
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 6845ebfa3067..f5f51d40a2ec 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -1263,44 +1263,6 @@ xfs_map_trim_size( bh_result->b_size = mapping_size; } -/* Bounce unaligned directio writes to the page cache. */ -static int -xfs_bounce_unaligned_dio_write( - struct xfs_inode *ip, - xfs_fileoff_t offset_fsb, - struct xfs_bmbt_irec *imap) -{ - struct xfs_bmbt_irec irec; - xfs_fileoff_t delta; - bool shared; - bool x; - int error; - - irec = *imap; - if (offset_fsb > irec.br_startoff) { - delta = offset_fsb - irec.br_startoff; - irec.br_blockcount -= delta; - irec.br_startblock += delta; - irec.br_startoff = offset_fsb; - } - error = xfs_reflink_trim_around_shared(ip, &irec, &shared, &x); - if (error) - return error; - - /* - * We're here because we're trying to do a directio write to a - * region that isn't aligned to a filesystem block. If any part - * of the extent is shared, fall back to buffered mode to handle - * the RMW. This is done by returning -EREMCHG ("remote addr - * changed"), which is caught further up the call stack. - */ - if (shared) { - trace_xfs_reflink_bounce_dio_write(ip, imap); - return -EREMCHG; - } - return 0; -} - STATIC int __xfs_get_blocks( struct inode *inode, @@ -1438,13 +1400,6 @@ __xfs_get_blocks( if (imap.br_startblock != HOLESTARTBLOCK && imap.br_startblock != DELAYSTARTBLOCK && (create || !ISUNWRITTEN(&imap))) { - if (create && direct && !is_cow) { - error = xfs_bounce_unaligned_dio_write(ip, offset_fsb, - &imap); - if (error) - return error; - } - xfs_map_buffer(inode, bh_result, &imap, offset); if (ISUNWRITTEN(&imap)) set_buffer_unwritten(bh_result); |