From: NeilBrown <neilb@suse.de>
Date: Mon, 10 Oct 2022 10:26:51 +1100
Subject: [PATCH] NFS: avoid spurious warning of lost lock that is being
 unlocked.
Git-commit: ef8d98f20dfc79777d2b66a30926533225dc6efa
Patch-mainline: v6.2
References: bsc#1221791

When the NFSv4 state manager recovers state after a server restart, it
reports that locks have been lost if it finds any lock state for which
recovery hasn't been successful.  i.e. any for which
NFS_LOCK_INITIALIZED is not set.

However it only tries to recover locks that are still linked to
inode->i_flctx.  So if a lock has been removed from inode->i_flctx, but
the state for that lock has not yet been destroyed, then a spurious
warning results.

nfs4_proc_unlck() calls locks_lock_inode_wait() - which removes the lock
from ->i_flctx - before sending the unlock request to the server and
before the final nfs4_put_lock_state() is called.  This allows a window
in which a spurious warning can be produced.

So add a new flag NFS_LOCK_UNLOCKING which is set once the decision has
been made to unlock the lock.  This will prevent it from triggering any
warning.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/nfs4_fs.h   |    1 +
 fs/nfs/nfs4proc.c  |    3 ++-
 fs/nfs/nfs4state.c |    3 ++-
 3 files changed, 5 insertions(+), 2 deletions(-)

--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -141,6 +141,7 @@ struct nfs4_lock_state {
 	struct nfs4_state *	ls_state;	/* Pointer to open state */
 #define NFS_LOCK_INITIALIZED 0
 #define NFS_LOCK_LOST        1
+#define NFS_LOCK_UNLOCKING   2
 	unsigned long		ls_flags;
 	struct nfs_seqid_counter	ls_seqid;
 	nfs4_stateid		ls_stateid;
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6334,12 +6334,13 @@ static int nfs4_proc_unlck(struct nfs4_s
 		mutex_unlock(&sp->so_delegreturn_mutex);
 		goto out;
 	}
+	lsp = request->fl_u.nfs4_fl.owner;
+	set_bit(NFS_LOCK_UNLOCKING, &lsp->ls_flags);
 	up_read(&nfsi->rwsem);
 	mutex_unlock(&sp->so_delegreturn_mutex);
 	if (status != 0)
 		goto out;
 	/* Is this a delegated lock? */
-	lsp = request->fl_u.nfs4_fl.owner;
 	if (test_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags) == 0)
 		goto out;
 	alloc_seqid = NFS_SERVER(inode)->nfs_client->cl_mvops->alloc_seqid;
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1587,7 +1587,8 @@ restart:
 				if (!test_bit(NFS_DELEGATED_STATE, &state->flags)) {
 					spin_lock(&state->state_lock);
 					list_for_each_entry(lock, &state->lock_states, ls_locks) {
-						if (!test_bit(NFS_LOCK_INITIALIZED, &lock->ls_flags))
+						if (!test_bit(NFS_LOCK_INITIALIZED, &lock->ls_flags) &&
+						    !test_bit(NFS_LOCK_UNLOCKING, &lock->ls_flags))
 							pr_warn_ratelimited("NFS: "
 									    "%s: Lock reclaim "
 									    "failed!\n", __func__);