btrfs: clean snapshots one by one

Each time pick one dead root from the list and let the caller know if
it's needed to continue. This should improve responsiveness during
umount and balance which at some point waits for cleaning all currently
queued dead roots.

A new dead root is added to the end of the list, so the snapshots
disappear in the order of deletion.

The snapshot cleaning work is now done only from the cleaner thread and the
others wake it if needed.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 0 insertions, 3 deletions

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 86f192ffc212..4ef5f7455fb3 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4148,10 +4148,7 @@ int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
 
         while (1) {
                 mutex_lock(&fs_info->cleaner_mutex);
-
-                btrfs_clean_old_snapshots(fs_info->tree_root);
                 ret = relocate_block_group(rc);
-
                 mutex_unlock(&fs_info->cleaner_mutex);
                 if (ret < 0) {
                         err = ret;