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authorQu Wenruo <quwenruo@cn.fujitsu.com>2015-08-25 10:44:57 +0800
committerDavid Sterba <dsterba@suse.com>2015-08-31 19:25:13 +0200
commit004eabb1ad09171389b7e9260342758e7b331a07 (patch)
tree3c6ffdc6392ecb98ccbc1d2e76d85e1a9ab29f7e /find-root.c
parent3eb8836424fd363fd7b4dda5cc602ed0040c3f8a (diff)
btrfs-progs: find-root: fix a bug that will cause wrong result
[BUG] btrfs-find-root may not output desire result, as due to search_extent_cache() may return a result that doesn't cover the desired range, generation cache can be screwed up if higher generation tree root is found before lower generation tree root. For example: ======= ./btrfs-find-root /dev/sda6 -a Superblock thinks the generation is 8 Superblock thinks the level is 0 adding bytenr: 4194304, gen: 8 <<< Debug output adding bytenr: 24715264, gen: 7 <<< gen is 7 at read_tree_block time Well block 4194304(gen: 8 level: 0) seems good, and it matches superblock Well block 24715264(gen: 8 level: 0) seems good, and it matches superblock <<< But its gen is wrong at result output time ======= [Fix] Add a new check to make sure the search_extent_cache() is returning the desired result. Reported-by: Marc Merlin <marc@merlins.org> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'find-root.c')
-rw-r--r--find-root.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/find-root.c b/find-root.c
index 1af37b54..55e79423 100644
--- a/find-root.c
+++ b/find-root.c
@@ -46,9 +46,14 @@ static int add_eb_to_result(struct extent_buffer *eb,
generation < filter->generation)
return ret;
- /* Get the generation cache or create one */
+ /*
+ * Get the generation cache or create one
+ *
+ * NOTE: search_cache_extent() may return cache that doesn't cover
+ * the range. So we need an extra check to make sure it's the right one.
+ */
cache = search_cache_extent(result, generation);
- if (!cache) {
+ if (!cache || cache->start != generation) {
gen_cache = malloc(sizeof(*gen_cache));
BUG_ON(!gen_cache);
cache = &gen_cache->cache;