btrfs: introduce BTRFS_NESTING_COW for cow'ing blocks
When we COW a block we are holding a lock on the original block, and
then we lock the new COW block. Because our lockdep maps are based on
root + level, this will make lockdep complain. We need a way to
indicate a subclass for locking the COW'ed block, so plumb through our
btrfs_lock_nesting from btrfs_cow_block down to the btrfs_init_buffer,
and then introduce BTRFS_NESTING_COW to be used for cow'ing blocks.
The reason I've added all this extra infrastructure is because there
will be need of different nesting classes in follow up patches.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4eb56f0..ed88724 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1205,7 +1205,8 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
root->root_key.type = BTRFS_ROOT_ITEM_KEY;
root->root_key.offset = 0;
- leaf = btrfs_alloc_tree_block(trans, root, 0, objectid, NULL, 0, 0, 0);
+ leaf = btrfs_alloc_tree_block(trans, root, 0, objectid, NULL, 0, 0, 0,
+ BTRFS_NESTING_NORMAL);
if (IS_ERR(leaf)) {
ret = PTR_ERR(leaf);
leaf = NULL;
@@ -1277,7 +1278,7 @@ static struct btrfs_root *alloc_log_tree(struct btrfs_trans_handle *trans,
*/
leaf = btrfs_alloc_tree_block(trans, root, 0, BTRFS_TREE_LOG_OBJECTID,
- NULL, 0, 0, 0);
+ NULL, 0, 0, 0, BTRFS_NESTING_NORMAL);
if (IS_ERR(leaf)) {
btrfs_put_root(root);
return ERR_CAST(leaf);