[PATCH 1/5] btrfs-progs: volume: Fix a bug causing btrfs-find-root to skip first chunk
From: Qu Wenruo <hidden>
Date: 2016-02-22 07:02:12
Subsystem:
the rest · Maintainer:
Linus Torvalds
There is a small bug from 2011, where btrfs_next_bg (formally btrfs_next_metadata) function will always skip the first chunk. That's OK for that time, as there is always 3 empty temporary chunks. But now, we may ended up with only one metadata or system chunk, with empty chunk auto-remove from kernel or new mkfs.btrfs. So fix it by checking the initial value so btrfs_next_bg() will return the first chunk if its *logical parameter is 0. Signed-off-by: Qu Wenruo <redacted> --- volumes.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/volumes.c b/volumes.c
index a94be0e..059c4f4 100644
--- a/volumes.c
+++ b/volumes.c@@ -1170,14 +1170,23 @@ int btrfs_next_bg(struct btrfs_mapping_tree *map_tree, u64 *logical, { struct cache_extent *ce; struct map_lookup *map; + u64 cur = *logical; - ce = search_cache_extent(&map_tree->cache_tree, *logical); + ce = search_cache_extent(&map_tree->cache_tree, cur); while (ce) { - ce = next_cache_extent(ce); - if (!ce) - return -ENOENT; + /* + * only jump to next bg if our cur is not 0 + * As the initial logical for btrfs_next_bg() is 0, and + * if we jump to next bg, we skipped a valid bg. + */ + if (cur) { + ce = next_cache_extent(ce); + if (!ce) + return -ENOENT; + } + cur = ce->start; map = container_of(ce, struct map_lookup, ce); if (map->type & type) { *logical = ce->start;
--
2.7.1