linux-kernel - [PATCH v3 2/3] nfs4: handle async processing of F_SETLK with FL

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Date:   Wed, 29 Dec 2021 11:24:43 +0300
From:   Vasily Averin <vvs@...tuozzo.com>
To:     Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        "J. Bruce Fields" <bfields@...ldses.org>
Cc:     kernel@...nvz.org, linux-nfs@...r.kernel.org,
        linux-kernel@...r.kernel.org, Chuck Lever <chuck.lever@...cle.com>
Subject: [PATCH v3 2/3] nfs4: handle async processing of F_SETLK with FL_SLEEP

nfsd and lockd use F_SETLK cmd with the FL_SLEEP flag set to request
asynchronous processing of blocking locks.

Currently nfs4 use locks_lock_inode_wait() function which is blocked
for such requests. To handle them correctly FL_SLEEP flag should be
temporarily reset before executing the locks_lock_inode_wait() function.

Additionally block flag is forced to set, to translate blocking lock to
remote nfs server, expecting it supports async processing of the blocking
locks too.

https://bugzilla.kernel.org/show_bug.cgi?id=215383
Signed-off-by: Vasily Averin <vvs@...tuozzo.com>
---
 fs/nfs/nfs4proc.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index ee3bc79f6ca3..9b1380c4223c 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -7094,7 +7094,7 @@ static int _nfs4_do_setlk(struct nfs4_state *state, int cmd, struct file_lock *f
 			recovery_type == NFS_LOCK_NEW ? GFP_KERNEL : GFP_NOFS);
 	if (data == NULL)
 		return -ENOMEM;
-	if (IS_SETLKW(cmd))
+	if (IS_SETLKW(cmd) || (fl->fl_flags & FL_SLEEP))
 		data->arg.block = 1;
 	nfs4_init_sequence(&data->arg.seq_args, &data->res.seq_res, 1,
 				recovery_type > NFS_LOCK_NEW);
@@ -7200,6 +7200,9 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock
 	int status;
 
 	request->fl_flags |= FL_ACCESS;
+	if (((fl_flags & FL_SLEEP_POSIX) == FL_SLEEP_POSIX) && IS_SETLK(cmd))
+		request->fl_flags &= ~FL_SLEEP;
+
 	status = locks_lock_inode_wait(state->inode, request);
 	if (status < 0)
 		goto out;
-- 
2.25.1