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btrfs-progs: volume: Fix a bug causing btrfs-find-root to skip first chunk 

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 <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
master
Qu Wenruo 2016-02-22 14:59:53 +08:00 committed by David Sterba
parent bfc2cb7cfb
commit e2e0dae926
1 changed files with 13 additions and 4 deletions
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17
volumes.c
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@ -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;