Commit 4dff97e6 authored by Josef Bacik's avatar Josef Bacik Committed by David Sterba

btrfs: introduce BTRFS_NESTING_SPLIT for split blocks

If we are splitting a leaf/node, we could do something like the
following

lock(leaf)  BTRFS_NESTING_NORMAL
  lock(left) BTRFS_NESTING_LEFT + BTRFS_NESTING_COW
    push from leaf -> left
      reset path to point to left
        split left
          allocate new block, lock block BTRFS_NESTING_SPLIT

at the new block point we need to have a different nesting level,
because we have already used either BTRFS_NESTING_LEFT or
BTRFS_NESTING_RIGHT when pushing items from the original leaf into the
adjacent leaves.
Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent bf59a5a2
...@@ -3537,7 +3537,7 @@ static noinline int split_node(struct btrfs_trans_handle *trans, ...@@ -3537,7 +3537,7 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
btrfs_node_key(c, &disk_key, mid); btrfs_node_key(c, &disk_key, mid);
split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level, split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
c->start, 0, BTRFS_NESTING_NORMAL); c->start, 0, BTRFS_NESTING_SPLIT);
if (IS_ERR(split)) if (IS_ERR(split))
return PTR_ERR(split); return PTR_ERR(split);
...@@ -4324,7 +4324,7 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans, ...@@ -4324,7 +4324,7 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
btrfs_item_key(l, &disk_key, mid); btrfs_item_key(l, &disk_key, mid);
right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0, right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
l->start, 0, BTRFS_NESTING_NORMAL); l->start, 0, BTRFS_NESTING_SPLIT);
if (IS_ERR(right)) if (IS_ERR(right))
return PTR_ERR(right); return PTR_ERR(right);
......
...@@ -52,6 +52,15 @@ enum btrfs_lock_nesting { ...@@ -52,6 +52,15 @@ enum btrfs_lock_nesting {
BTRFS_NESTING_LEFT_COW, BTRFS_NESTING_LEFT_COW,
BTRFS_NESTING_RIGHT_COW, BTRFS_NESTING_RIGHT_COW,
/*
* When splitting we may push nodes to the left or right, but still use
* the subsequent nodes in our path, keeping our locks on those adjacent
* blocks. Thus when we go to allocate a new split block we've already
* used up all of our available subclasses, so this subclass exists to
* handle this case where we need to allocate a new split block.
*/
BTRFS_NESTING_SPLIT,
/* /*
* We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so * We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so
* add this in here and add a static_assert to keep us from going over * add this in here and add a static_assert to keep us from going over
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment