dm space map common: fix division bug in sm_ll_find_free_block()

commit 5208692e80a1f3c8ce2063a22b675dd5589d1d80 upstream.

This division bug meant the search for free metadata space could skip
the final allocation bitmap's worth of entries. Fix affects DM thinp,
cache and era targets.

Cc: [email protected]
Signed-off-by: Joe Thornber <[email protected]>
Tested-by: Ming-Hung Tsai <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: jthornber

drivers/md/persistent-data/dm-space-map-common.c

@@ -337,6 +337,8 @@ int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
 	 */
 	begin = do_div(index_begin, ll->entries_per_block);
 	end = do_div(end, ll->entries_per_block);
+	if (end == 0)
+		end = ll->entries_per_block;
 
 	for (i = index_begin; i < index_end; i++, begin = 0) {
 		struct dm_block *blk;