From: Darrick J. Wong Date: Thu, 3 Oct 2024 15:09:32 +0000 (-0700) Subject: fsdax: remove zeroing code from dax_unshare_iter X-Git-Tag: v6.12-rc6~27^2~1^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=95472274b6fed8f2d30fbdda304e12174b3d4099;p=thirdparty%2Flinux.git fsdax: remove zeroing code from dax_unshare_iter Remove the code in dax_unshare_iter that zeroes the destination memory because it's not necessary. If srcmap is unwritten, we don't have to do anything because that unwritten extent came from the regular file mapping, and unwritten extents cannot be shared. The same applies to holes. Furthermore, zeroing to unshare a mapping is just plain wrong because unsharing means copy on write, and we should be copying data. This is effectively a revert of commit 13dd4e04625f ("fsdax: unshare: zero destination if srcmap is HOLE or UNWRITTEN") Cc: ruansy.fnst@fujitsu.com Signed-off-by: Darrick J. Wong Link: https://lore.kernel.org/r/172796813311.1131942.16033376284752798632.stgit@frogsfrogsfrogs Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner --- diff --git a/fs/dax.c b/fs/dax.c index 5064eefb1c1e4..9fbbdaa784b43 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1276,14 +1276,6 @@ static s64 dax_unshare_iter(struct iomap_iter *iter) if (ret < 0) goto out_unlock; - /* zero the distance if srcmap is HOLE or UNWRITTEN */ - if (srcmap->flags & IOMAP_F_SHARED || srcmap->type == IOMAP_UNWRITTEN) { - memset(daddr, 0, length); - dax_flush(iomap->dax_dev, daddr, length); - ret = length; - goto out_unlock; - } - ret = dax_iomap_direct_access(srcmap, pos, length, &saddr, NULL); if (ret < 0) goto out_unlock;