From 4f29e10d689f5678b947df978bd0c96e4d70686f Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Thu, 21 Feb 2019 16:36:17 -0800 Subject: [PATCH] xfs: rework breaking of shared extents in xfs_file_iomap_begin Rework the data flow in xfs_file_iomap_begin where we decide if we have to break shared extents. Signed-off-by: Darrick J. Wong Reviewed-by: Brian Foster --- fs/xfs/xfs_iomap.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index fa6621448d5e..63d323916bba 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -982,7 +982,7 @@ xfs_file_iomap_begin( * been done up front, so we don't need to do them here. */ if (xfs_is_cow_inode(ip)) { - struct xfs_bmbt_irec orig = imap; + struct xfs_bmbt_irec cmap; bool directio = (flags & IOMAP_DIRECT); /* if zeroing doesn't need COW allocation, then we are done. */ @@ -991,7 +991,8 @@ xfs_file_iomap_begin( goto out_found; /* may drop and re-acquire the ilock */ - error = xfs_reflink_allocate_cow(ip, &imap, &shared, &lockmode, + cmap = imap; + error = xfs_reflink_allocate_cow(ip, &cmap, &shared, &lockmode, directio); if (error) goto out_unlock; @@ -1002,10 +1003,11 @@ xfs_file_iomap_begin( * write code can perform read-modify-write operations; we * won't need the CoW fork mapping until writeback. For direct * I/O, which must be block aligned, we need to report the - * newly allocated address. + * newly allocated address. If the data fork has a hole, copy + * the COW fork mapping to avoid allocating to the data fork. */ - if (!directio && orig.br_startblock != HOLESTARTBLOCK) - imap = orig; + if (directio || imap.br_startblock == HOLESTARTBLOCK) + imap = cmap; end_fsb = imap.br_startoff + imap.br_blockcount; length = XFS_FSB_TO_B(mp, end_fsb) - offset;