[PATCH 6.4 530/800] btrfs: do not BUG_ON() on tree mod log failure at balance_level()

Greg Kroah-Hartman
2023-07-16T20:18:27Z

From: Filipe Manana <fdmanana@suse.com>

commit 39020d8abc7ec62c4de9b260e3d10d4a1c2478ce upstream.

At balance_level(), instead of doing a BUG_ON() in case we fail to record
tree mod log operations, do a transaction abort and return the error to
the callers. There's really no need for the BUG_ON() as we can release
all resources in this context, and we have to abort because other future
tree searches that use the tree mod log (btrfs_search_old_slot()) may get
inconsistent results if other operations modify the tree after that
failure and before the tree mod log based search.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/ctree.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1042,7 +1042,12 @@ static noinline int balance_level(struct
}

ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
- BUG_ON(ret < 0);
+ if (ret < 0) {
+ btrfs_tree_unlock(child);
+ free_extent_buffer(child);
+ btrfs_abort_transaction(trans, ret);
+ goto enospc;
+ }
rcu_assign_pointer(root->node, child);

add_root_to_dirty_list(root);
@@ -1130,7 +1135,10 @@ static noinline int balance_level(struct
btrfs_node_key(right, &right_key, 0);
ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
BTRFS_MOD_LOG_KEY_REPLACE);
- BUG_ON(ret < 0);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto enospc;
+ }
btrfs_set_node_key(parent, &right_key, pslot + 1);
btrfs_mark_buffer_dirty(parent);
}
@@ -1176,7 +1184,10 @@ static noinline int balance_level(struct
btrfs_node_key(mid, &mid_key, 0);
ret = btrfs_tree_mod_log_insert_key(parent, pslot,
BTRFS_MOD_LOG_KEY_REPLACE);
- BUG_ON(ret < 0);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, ret);
+ goto enospc;
+ }
btrfs_set_node_key(parent, &mid_key, pslot);
btrfs_mark_buffer_dirty(parent);
}