dm btree: fix for dm_btree_find_lowest_key()

BugLink: http://bugs.launchpad.net/bugs/1694621
commit 7d1fedb6e96a960aa91e4ff70714c3fb09195a5a upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index b1ced58eb5e1475b440a15de0e26811fb90b8159..a1a68209bd364abf37aa65b685717b69392cbd82 100644 (file)
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -887,8 +887,12 @@ 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);