linux-kernel - [PATCH 4.4 30/87] locks: dont check for race with close when setting OFD lock

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Message-Id: <20180115123352.345392820@linuxfoundation.org>
Date:   Mon, 15 Jan 2018 13:34:29 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jeff Layton <jeff.layton@...marydata.com>,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Mel Gorman <mgorman@...e.de>
Subject: [PATCH 4.4 30/87] locks: dont check for race with close when setting OFD lock

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeff Layton <jeff.layton@...marydata.com>

commit 0752ba807b04ccd69cb4bc8bbf829a80ee208a3c upstream.

We don't clean out OFD locks on close(), so there's no need to check
for a race with them here. They'll get cleaned out at the same time
that flock locks are.

Signed-off-by: Jeff Layton <jeff.layton@...marydata.com>
Acked-by: "J. Bruce Fields" <bfields@...ldses.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Mel Gorman <mgorman@...e.de>


---
 fs/locks.c |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2220,10 +2220,12 @@ int fcntl_setlk(unsigned int fd, struct
 	error = do_lock_file_wait(filp, cmd, file_lock);
 
 	/*
-	 * Attempt to detect a close/fcntl race and recover by
-	 * releasing the lock that was just acquired.
+	 * Attempt to detect a close/fcntl race and recover by releasing the
+	 * lock that was just acquired. There is no need to do that when we're
+	 * unlocking though, or for OFD locks.
 	 */
-	if (!error && file_lock->fl_type != F_UNLCK) {
+	if (!error && file_lock->fl_type != F_UNLCK &&
+	    !(file_lock->fl_flags & FL_OFDLCK)) {
 		/*
 		 * We need that spin_lock here - it prevents reordering between
 		 * update of i_flctx->flc_posix and check for it done in
@@ -2362,10 +2364,12 @@ int fcntl_setlk64(unsigned int fd, struc
 	error = do_lock_file_wait(filp, cmd, file_lock);
 
 	/*
-	 * Attempt to detect a close/fcntl race and recover by
-	 * releasing the lock that was just acquired.
+	 * Attempt to detect a close/fcntl race and recover by releasing the
+	 * lock that was just acquired. There is no need to do that when we're
+	 * unlocking though, or for OFD locks.
 	 */
-	if (!error && file_lock->fl_type != F_UNLCK) {
+	if (!error && file_lock->fl_type != F_UNLCK &&
+	    !(file_lock->fl_flags & FL_OFDLCK)) {
 		/*
 		 * We need that spin_lock here - it prevents reordering between
 		 * update of i_flctx->flc_posix and check for it done in