From 5208692e80a1f3c8ce2063a22b675dd5589d1d80 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Tue, 13 Apr 2021 09:11:53 +0100
Subject: [PATCH] dm space map common: fix division bug in
 sm_ll_find_free_block()
Git-commit: 5208692e80a1f3c8ce2063a22b675dd5589d1d80
Patch-mainline: v5.13-rc1
References: git-fixes

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: Coly Li <colyli@suse.de>

---
 drivers/md/persistent-data/dm-space-map-common.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/md/persistent-data/dm-space-map-common.c b/drivers/md/persistent-data/dm-space-map-common.c
index d8b4125e338c..a213bf11738f 100644
--- 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;
-- 
2.35.3