[PATCH 5.10 372/406] btrfs: dont start transaction when joining with TRANS_JOIN_NOSTART

Greg Kroah-Hartman
2023-09-17T19:41:16Z

From: Filipe Manana <fdmanana@suse.com>

commit 4490e803e1fe9fab8db5025e44e23b55df54078b upstream.

When joining a transaction with TRANS_JOIN_NOSTART, if we don't find a
running transaction we end up creating one. This goes against the purpose
of TRANS_JOIN_NOSTART which is to join a running transaction if its state
is at or below the state TRANS_STATE_COMMIT_START, otherwise return an
-ENOENT error and don't start a new transaction. So fix this to not create
a new transaction if there's no running transaction at or below that
state.

CC: stable@vger.kernel.org # 4.14+
Fixes: a6d155d2e363 ("Btrfs: fix deadlock between fiemap and transaction commits")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/transaction.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -301,10 +301,11 @@ loop:
spin_unlock(&fs_info->trans_lock);

/*
- * If we are ATTACH, we just want to catch the current transaction,
- * and commit it. If there is no transaction, just return ENOENT.
+ * If we are ATTACH or TRANS_JOIN_NOSTART, we just want to catch the
+ * current transaction, and commit it. If there is no transaction, just
+ * return ENOENT.
*/
- if (type == TRANS_ATTACH)
+ if (type == TRANS_ATTACH || type == TRANS_JOIN_NOSTART)
return -ENOENT;

/*