[PATCH 5.5 199/367] btrfs: drop log root for dropped roots

Greg Kroah-Hartman
2020-02-10T13:01:19Z

From: Josef Bacik <josef@toxicpanda.com>

commit 889bfa39086e86b52fcfaa04d72c95eaeb12f9a5 upstream.

If we fsync on a subvolume and create a log root for that volume, and
then later delete that subvolume we'll never clean up its log root. Fix
this by making switch_commit_roots free the log for any dropped roots we
encounter. The extra churn is because we need a btrfs_trans_handle, not
the btrfs_transaction.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/btrfs/transaction.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)

--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -147,13 +147,14 @@ void btrfs_put_transaction(struct btrfs_
}
}

-static noinline void switch_commit_roots(struct btrfs_transaction *trans)
+static noinline void switch_commit_roots(struct btrfs_trans_handle *trans)
{
+ struct btrfs_transaction *cur_trans = trans->transaction;
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_root *root, *tmp;

down_write(&fs_info->commit_root_sem);
- list_for_each_entry_safe(root, tmp, &trans->switch_commits,
+ list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits,
dirty_list) {
list_del_init(&root->dirty_list);
free_extent_buffer(root->commit_root);
@@ -165,16 +166,17 @@ static noinline void switch_commit_roots
}

/* We can free old roots now. */
- spin_lock(&trans->dropped_roots_lock);
- while (!list_empty(&trans->dropped_roots)) {
- root = list_first_entry(&trans->dropped_roots,
+ spin_lock(&cur_trans->dropped_roots_lock);
+ while (!list_empty(&cur_trans->dropped_roots)) {
+ root = list_first_entry(&cur_trans->dropped_roots,
struct btrfs_root, root_list);
list_del_init(&root->root_list);
- spin_unlock(&trans->dropped_roots_lock);
+ spin_unlock(&cur_trans->dropped_roots_lock);
+ btrfs_free_log(trans, root);
btrfs_drop_and_free_fs_root(fs_info, root);
- spin_lock(&trans->dropped_roots_lock);
+ spin_lock(&cur_trans->dropped_roots_lock);
}
- spin_unlock(&trans->dropped_roots_lock);
+ spin_unlock(&cur_trans->dropped_roots_lock);
up_write(&fs_info->commit_root_sem);
}

@@ -1421,7 +1423,7 @@ static int qgroup_account_snapshot(struc
ret = commit_cowonly_roots(trans);
if (ret)
goto out;
- switch_commit_roots(trans->transaction);
+ switch_commit_roots(trans);
ret = btrfs_write_and_wait_transaction(trans);
if (ret)
btrfs_handle_fs_error(fs_info, ret,
@@ -2309,7 +2311,7 @@ int btrfs_commit_transaction(struct btrf
list_add_tail(&fs_info->chunk_root->dirty_list,
&cur_trans->switch_commits);

- switch_commit_roots(cur_trans);
+ switch_commit_roots(trans);

ASSERT(list_empty(&cur_trans->dirty_bgs));
ASSERT(list_empty(&cur_trans->io_bgs));