From: Josef Bacik <josef@toxicpanda.com>
Date: Fri, 12 Mar 2021 15:24:58 -0500
Subject: btrfs: handle errors from select_reloc_root()
Git-commit: cbdc2ebc7c42a744d2f52a8a4adb0b725798469e
Patch-mainline: v5.13-rc1
References: bsc#1187833
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>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
fs/btrfs/relocation.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index e5fbc2c00166..146c7dbcf04c 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -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) {