[PATCH v2] btrfs: Don't panic when we can't find a root key

[PATCH v2] btrfs: Don't panic when we can't find a root key

[Qu Wenruo]

When we failed to find a root key in btrfs_update_root(), we just panic.

That's definitely not cool, fix it by outputting an unique error
message, aborting current transaction and return -EUCLEAN.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
changelog:
v2:
- Remove the tree leaf dump, as it doesn't help much.
- Change return value to -EUCLEAN to show it's a corruption.
---
 fs/btrfs/root-tree.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 65bda0682928..7f5c98afce25 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -137,11 +137,14 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 		goto out;
 	}
 
-	if (ret != 0) {
-		btrfs_print_leaf(path->nodes[0]);
-		btrfs_crit(fs_info, "unable to update root key %llu %u %llu",
-			   key->objectid, key->type, key->offset);
-		BUG_ON(1);
+	if (ret > 0) {
+		btrfs_crit(fs_info,
+			"unable to find root key (%llu %u %llu) in tree %llu",
+			   key->objectid, key->type, key->offset,
+			   root->root_key.objectid);
+		ret = -EUCLEAN;
+		btrfs_abort_transaction(trans, ret);
+		goto out;
 	}
 
 	l = path->nodes[0];
-- 
2.21.0

Re: [PATCH v2] btrfs: Don't panic when we can't find a root key

[David Sterba]

On Tue, Feb 26, 2019 at 04:33:56PM +0800, Qu Wenruo wrote:
> When we failed to find a root key in btrfs_update_root(), we just panic.
> 
> That's definitely not cool, fix it by outputting an unique error
> message, aborting current transaction and return -EUCLEAN.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Reviewed-by: David Sterba <dsterba@suse.com>

I've added a sentence why the error should not normally happen.