From:   Vasily Averin <vvs@virtuozzo.com>
Subject: [PATCH v3 1/3] nfs: local_lock: handle async processing of F_SETLK
 with FL_SLEEP
To:     Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        "J. Bruce Fields" <bfields@fieldses.org>
Cc:     kernel@openvz.org, linux-nfs@vger.kernel.org,
        linux-kernel@vger.kernel.org, Chuck Lever <chuck.lever@oracle.com>
References: <1f354cec-d2d6-ddf5-56e0-325c10fe26ee@virtuozzo.com>
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Date:   Wed, 29 Dec 2021 11:24:34 +0300
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nfsd and lockd use F_SETLK cmd with FL_SLEEP and FL_POSIX flags set
to request asynchronous processing of blocking locks.

Currently nfs mounted with 'local_lock' option use locks_lock_file_wait()
function which is blocked for such requests. To handle them correctly
non-blocking posix_file_lock() function should be used instead.

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

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 24e7dccce355..83cf42cabe41 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -753,6 +753,7 @@ static int
 do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
 {
 	struct inode *inode = filp->f_mapping->host;
+	unsigned int flags = fl->fl_flags;
 	int status;
 
 	/*
@@ -769,9 +770,11 @@ do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
 	 */
 	if (!is_local)
 		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
+	else if (((flags & FL_SLEEP_POSIX) == FL_SLEEP_POSIX) && IS_SETLK(cmd))
+		status = posix_lock_file(filp, fl, NULL);
 	else
 		status = locks_lock_file_wait(filp, fl);
-	if (status < 0)
+	if (status)
 		goto out;
 
 	/*
diff --git a/include/linux/fs.h b/include/linux/fs.h
index bbf812ce89a8..8b6e9332b39f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1042,6 +1042,7 @@ static inline struct file *get_file(struct file *f)
 #define FL_RECLAIM	4096	/* reclaiming from a reboot server */
 
 #define FL_CLOSE_POSIX (FL_POSIX | FL_CLOSE)
+#define FL_SLEEP_POSIX (FL_POSIX | FL_SLEEP)
 
 /*
  * Special return value from posix_lock_file() and vfs_lock_file() for
-- 
2.25.1