| Message ID | 1440470697-21177-2-git-send-email-quwenruo@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Tue, Aug 25, 2015 at 10:44:57AM +0800, Qu Wenruo wrote: > [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@merlins.org> > Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
======= ./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@merlins.org> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> --- 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;