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

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Message-Id: <20200210122442.934140062@linuxfoundation.org>
Date:   Mon, 10 Feb 2020 04:31:52 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Filipe Manana <fdmanana@...e.com>,
        Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>
Subject: [PATCH 5.5 199/367] btrfs: drop log root for dropped roots

From: Josef Bacik <josef@...icpanda.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@...r.kernel.org # 5.4+
Reviewed-by: Filipe Manana <fdmanana@...e.com>
Signed-off-by: Josef Bacik <josef@...icpanda.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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));