linux-kernel - [PATCH 4.9 04/23] ceph: unlock dangling spinlock in try_flush

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Message-Id: <20171031095517.584837254@linuxfoundation.org>
Date:   Tue, 31 Oct 2017 10:55:28 +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 <jlayton@...hat.com>,
        "Yan, Zheng" <zyan@...hat.com>, Ilya Dryomov <idryomov@...il.com>
Subject: [PATCH 4.9 04/23] ceph: unlock dangling spinlock in try_flush_caps()

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

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

From: Jeff Layton <jlayton@...hat.com>

commit 6c2838fbdedb9b72a81c931d49e56b229b6cdbca upstream.

sparse warns:

  fs/ceph/caps.c:2042:9: warning: context imbalance in 'try_flush_caps' - wrong count at exit

We need to exit this function with the lock unlocked, but a couple of
cases leave it locked.

Signed-off-by: Jeff Layton <jlayton@...hat.com>
Reviewed-by: "Yan, Zheng" <zyan@...hat.com>
Reviewed-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/ceph/caps.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1900,6 +1900,7 @@ static int try_flush_caps(struct inode *
 retry:
 	spin_lock(&ci->i_ceph_lock);
 	if (ci->i_ceph_flags & CEPH_I_NOFLUSH) {
+		spin_unlock(&ci->i_ceph_lock);
 		dout("try_flush_caps skipping %p I_NOFLUSH set\n", inode);
 		goto out;
 	}
@@ -1917,8 +1918,10 @@ retry:
 			mutex_lock(&session->s_mutex);
 			goto retry;
 		}
-		if (cap->session->s_state < CEPH_MDS_SESSION_OPEN)
+		if (cap->session->s_state < CEPH_MDS_SESSION_OPEN) {
+			spin_unlock(&ci->i_ceph_lock);
 			goto out;
+		}
 
 		flushing = __mark_caps_flushing(inode, session, true,
 						&flush_tid, &oldest_flush_tid);