From 1f1397b7218d7f8e53e33c6b58cbf9601cd2d8e6 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Tue, 2 May 2023 09:14:51 +1000 Subject: [PATCH] xfs: don't allocate into the data fork for an unshare request For an unshare request, we only have to take action if the data fork has a shared mapping. We don't care if someone else set up a cow operation. If we find nothing in the data fork, return a hole to avoid allocating space. Note that fallocate will replace the delalloc reservation with an unwritten extent anyway, so this has no user-visible effects outside of avoiding unnecessary updates. Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- fs/xfs/xfs_iomap.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 285885c..18c8f16 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -1006,8 +1006,9 @@ xfs_buffered_write_iomap_begin( if (eof) imap.br_startoff = end_fsb; /* fake hole until the end */ - /* We never need to allocate blocks for zeroing a hole. */ - if ((flags & IOMAP_ZERO) && imap.br_startoff > offset_fsb) { + /* We never need to allocate blocks for zeroing or unsharing a hole. */ + if ((flags & (IOMAP_UNSHARE | IOMAP_ZERO)) && + imap.br_startoff > offset_fsb) { xfs_hole_to_iomap(ip, iomap, offset_fsb, imap.br_startoff); goto out_unlock; } -- 2.7.4