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: stable@vger.kernel.org
Signed-off-by: Joe Thornber <ejt@redhat.com>
Tested-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/persistent-data/dm-space-map-common.c b/drivers/md/persistent-data/dm-space-map-common.c
index d8b4125e338ca84f05884876aaf64488c5d28ace..a213bf11738fbbb10448d09abfb8d532679f011e 100644 (file)
--- a/drivers/md/persistent-data/dm-space-map-common.c
+++ b/drivers/md/persistent-data/dm-space-map-common.c
@@ -339,6 +339,8 @@ 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;