From: Filipe Manana fdmanana@suse.com
commit 0004ff15ea26015a0a3a6182dca3b9d1df32e2b7 upstream.
When loading a free space cache from disk, at __load_free_space_cache(), if we fail to insert a bitmap entry, we still increment the number of total bitmaps in the btrfs_free_space_ctl structure, which is incorrect since we failed to add the bitmap entry. On error we then empty the cache by calling __btrfs_remove_free_space_cache(), which will result in getting the total bitmaps counter set to 1.
A failure to load a free space cache is not critical, so if a failure happens we just rebuild the cache by scanning the extent tree, which happens at block-group.c:caching_thread(). Yet the failure will result in having the total bitmaps of the btrfs_free_space_ctl always bigger by 1 then the number of bitmap entries we have. So fix this by having the total bitmaps counter be incremented only if we successfully added the bitmap entry.
Fixes: a67509c30079 ("Btrfs: add a io_ctl struct and helpers for dealing with the space cache") Reviewed-by: Anand Jain anand.jain@oracle.com CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Filipe Manana fdmanana@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/free-space-cache.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
--- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -870,15 +870,16 @@ static int __load_free_space_cache(struc } spin_lock(&ctl->tree_lock); ret = link_free_space(ctl, e); - ctl->total_bitmaps++; - recalculate_thresholds(ctl); - spin_unlock(&ctl->tree_lock); if (ret) { + spin_unlock(&ctl->tree_lock); btrfs_err(fs_info, "Duplicate entries in free space cache, dumping"); kmem_cache_free(btrfs_free_space_cachep, e); goto free_cache; } + ctl->total_bitmaps++; + recalculate_thresholds(ctl); + spin_unlock(&ctl->tree_lock); list_add_tail(&e->list, &bitmaps); }