dm btree: fix for dm_btree_find_lowest_key()

dm_btree_find_lowest_key() is giving incorrect results.  find_key()
traverses the btree correctly for finding the highest key, but there is
an error in the way it traverses the btree for retrieving the lowest
key.  dm_btree_find_lowest_key() fetches the first key of the rightmost
block of the btree instead of fetching the first key from the leftmost
block.

Fix this by conditionally passing the correct parameter to value64()
based on the @find_highest flag.

Cc: stable@vger.kernel.org
Signed-off-by: Erez Zadok <ezk@fsl.cs.sunysb.edu>
Signed-off-by: Vinothkumar Raja <vinraja@cs.stonybrook.edu>
Signed-off-by: Nidhi Panpalia <npanpalia@cs.stonybrook.edu>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index 02e2ee0d8a00bbff8fdd026e1ab059af06730faf..f21ce6a3d4cf563ed7b768f65f7452e55af99826 100644 (file)
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -902,8 +902,12 @@ static int find_key(struct ro_spine *s, dm_block_t block, bool find_highest,
                else
                        *result_key = le64_to_cpu(ro_node(s)->keys[0]);
 
-               if (next_block || flags & INTERNAL_NODE)
-                       block = value64(ro_node(s), i);
+               if (next_block || flags & INTERNAL_NODE) {
+                       if (find_highest)
+                               block = value64(ro_node(s), i);
+                       else
+                               block = value64(ro_node(s), 0);
+               }
 
        } while (flags & INTERNAL_NODE);