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-rw-r--r--fs/btrfs/extent-tree.c44
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);