[BUG]
btrfs-find-root may not output desire result, as due to
search_extent_cache() may return result which 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 judgment to make sure the search_extent_cache() is returning
desired result.
Reported-by: Marc Merlin <marc@xxxxxxxxxxx>
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
find-root.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/find-root.c b/find-root.c
index 1af37b5..0eca0ab 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 doesn't cover
+ * the range. So need extra judgement to make sure it's a match.
+ */
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;
--
2.5.0
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