xfs: xfs_bmap_finish_one should map unwritten extents properly

The deferred bmap work state and the log item can transmit unwritten
state, so the XFS_BMAP_MAP handler must map in extents with that
unwritten state.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_bmap.c

@@ -6245,6 +6245,8 @@ xfs_bmap_finish_one(
 
 	switch (bi->bi_type) {
 	case XFS_BMAP_MAP:
+		if (bi->bi_bmap.br_state == XFS_EXT_UNWRITTEN)
+			flags |= XFS_BMAPI_PREALLOC;
 		error = xfs_bmapi_remap(tp, bi->bi_owner, bmap->br_startoff,
 				bmap->br_blockcount, bmap->br_startblock,
 				flags);