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 17aef55ed708a2addd1adfc9d6ab0ddaf2c83927..a284762e548e1dc840cef28df8f2167220b26051 100644 (file)
--- a/drivers/md/persistent-data/dm-space-map-common.c
+++ b/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;