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author | Qu Wenruo <quwenruo@cn.fujitsu.com> | 2015-08-25 10:44:57 +0800 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2015-08-31 19:25:13 +0200 |
commit | 004eabb1ad09171389b7e9260342758e7b331a07 (patch) | |
tree | 3c6ffdc6392ecb98ccbc1d2e76d85e1a9ab29f7e /find-root.c | |
parent | 3eb8836424fd363fd7b4dda5cc602ed0040c3f8a (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.c | 9 |
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; |