xfs: fix partially uninitialized structure in xfs_reflink_remap_extent

stable inclusion
from linux-4.19.120
commit 9276babd9d734be6b3aa95a24b834f4e88366dc1

--------------------------------

[ Upstream commit c142932c ]

In the reflink extent remap function, it turns out that uirec (the block
mapping corresponding only to the part of the passed-in mapping that got
unmapped) was not fully initialized.  Specifically, br_state was not
being copied from the passed-in struct to the uirec.  This could lead to
unpredictable results such as the reflinked mapping being marked
unwritten in the destination file.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

fs/xfs/xfs_reflink.c

@@ -1058,6 +1058,7 @@ xfs_reflink_remap_extent(
 		uirec.br_startblock = irec->br_startblock + rlen;
 		uirec.br_startoff = irec->br_startoff + rlen;
 		uirec.br_blockcount = unmap_len - rlen;
+		uirec.br_state = irec->br_state;
 		unmap_len = rlen;
 
 		/* If this isn't a real mapping, we're done. */