diff options
| -rw-r--r-- | fs/btrfs/extent-tree.c | 44 |
1 files changed, 27 insertions, 17 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 1eef4ee01d1a..fc0db9887c0e 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3408,17 +3408,14 @@ int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans, int loops = 0; spin_lock(&cur_trans->dirty_bgs_lock); - if (!list_empty(&cur_trans->dirty_bgs)) { - list_splice_init(&cur_trans->dirty_bgs, &dirty); + if (list_empty(&cur_trans->dirty_bgs)) { + spin_unlock(&cur_trans->dirty_bgs_lock); + return 0; } + list_splice_init(&cur_trans->dirty_bgs, &dirty); spin_unlock(&cur_trans->dirty_bgs_lock); again: - if (list_empty(&dirty)) { - btrfs_free_path(path); - return 0; - } - /* * make sure all the block groups on our dirty list actually * exist @@ -3431,18 +3428,16 @@ again: return -ENOMEM; } + /* + * cache_write_mutex is here only to save us from balance or automatic + * removal of empty block groups deleting this block group while we are + * writing out the cache + */ + mutex_lock(&trans->transaction->cache_write_mutex); while (!list_empty(&dirty)) { cache = list_first_entry(&dirty, struct btrfs_block_group_cache, dirty_list); - - /* - * cache_write_mutex is here only to save us from balance - * deleting this block group while we are writing out the - * cache - */ - mutex_lock(&trans->transaction->cache_write_mutex); - /* * this can happen if something re-dirties a block * group that is already under IO. Just wait for it to @@ -3495,7 +3490,6 @@ again: } if (!ret) ret = write_one_cache_group(trans, root, path, cache); - mutex_unlock(&trans->transaction->cache_write_mutex); /* if its not on the io list, we need to put the block group */ if (should_put) @@ -3503,7 +3497,16 @@ again: if (ret) break; + + /* + * Avoid blocking other tasks for too long. It might even save + * us from writing caches for block groups that are going to be + * removed. + */ + mutex_unlock(&trans->transaction->cache_write_mutex); + mutex_lock(&trans->transaction->cache_write_mutex); } + mutex_unlock(&trans->transaction->cache_write_mutex); /* * go through delayed refs for all the stuff we've just kicked off @@ -3514,8 +3517,15 @@ again: loops++; spin_lock(&cur_trans->dirty_bgs_lock); list_splice_init(&cur_trans->dirty_bgs, &dirty); + /* + * dirty_bgs_lock protects us from concurrent block group + * deletes too (not just cache_write_mutex). + */ + if (!list_empty(&dirty)) { + spin_unlock(&cur_trans->dirty_bgs_lock); + goto again; + } spin_unlock(&cur_trans->dirty_bgs_lock); - goto again; } btrfs_free_path(path); |