[PATCH 6.4 028/800] lockd: drop inappropriate svc_get() from locked_get()

Greg Kroah-Hartman
2023-07-16T19:55:25Z

From: NeilBrown <neilb@suse.de>

[ Upstream commit 665e89ab7c5af1f2d260834c861a74b01a30f95f ]

The below-mentioned patch was intended to simplify refcounting on the
svc_serv used by locked. The goal was to only ever have a single
reference from the single thread. To that end we dropped a call to
lockd_start_svc() (except when creating thread) which would take a
reference, and dropped the svc_put(serv) that would drop that reference.

Unfortunately we didn't also remove the svc_get() from
lockd_create_svc() in the case where the svc_serv already existed.
So after the patch:
- on the first call the svc_serv was allocated and the one reference
was given to the thread, so there are no extra references
- on subsequent calls svc_get() was called so there is now an extra
reference.
This is clearly not consistent.

The inconsistency is also clear in the current code in lockd_get()
takes *two* references, one on nlmsvc_serv and one by incrementing
nlmsvc_users. This clearly does not match lockd_put().

So: drop that svc_get() from lockd_get() (which used to be in
lockd_create_svc().

Reported-by: Ido Schimmel <idosch@idosch.org>
Closes: https://lore.kernel.org/linux-nfs/ZHsI%2FH16VX9kJQX1@shredder/T/#u
Fixes: b73a2972041b ("lockd: move lockd_start_svc() call into lockd_create_svc()")
Signed-off-by: NeilBrown <neilb@suse.de>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/lockd/svc.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 04ba95b83d168..22d3ff3818f5f 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -355,7 +355,6 @@ static int lockd_get(void)
int error;

if (nlmsvc_serv) {
- svc_get(nlmsvc_serv);
nlmsvc_users++;
return 0;
}
--
2.39.2