Commit cbdc2ebc authored Mar 12, 2021 by Josef Bacik Committed by David Sterba Apr 19, 2021

btrfs: handle errors from select_reloc_root()



Currently select_reloc_root() doesn't return an error, but followup
patches will make it possible for it to return an error.  We do have
proper error recovery in do_relocation however, so handle the
possibility of select_reloc_root() having an error properly instead of
BUG_ON(!root).

I've also adjusted select_reloc_root() to return ERR_PTR(-ENOENT) if we
don't find a root, instead of NULL, to make the error case easier to
deal with.  I've replaced the BUG_ON(!root) with an ASSERT(0) for this
case as it indicates we messed up the backref walking code, but it could
also indicate corruption.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 1c7bfa15

fs/btrfs/relocation.c

+12 −3

Original line number	Diff line number	Diff line
		@@ -2024,8 +2024,14 @@ struct btrfs_root select_reloc_root(struct btrfs_trans_handle trans,
		if (!next \|\| next->level <= node->level)
		break;
		}
		if (!root)
		return NULL;
		if (!root) {
		/*
		* This can happen if there's fs corruption or if there's a bug
		* in the backref lookup code.
		*/
		ASSERT(0);
		return ERR_PTR(-ENOENT);
		}

		next = node;
		/* setup backref node path for btrfs_reloc_cow_block */
		@@ -2196,7 +2202,10 @@ static int do_relocation(struct btrfs_trans_handle *trans,

		upper = edge->node[UPPER];
		root = select_reloc_root(trans, rc, upper, edges);
		BUG_ON(!root);
		if (IS_ERR(root)) {
		ret = PTR_ERR(root);
		goto next;
		}

		if (upper->eb && !upper->locked) {
		if (!lowest) {