linux-kernel - [PATCH] ocfs2: fix unbalanced locking

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Message-ID: <20200724124443.GA28164@duo.ucw.cz>
Date:   Fri, 24 Jul 2020 14:44:43 +0200
From:   Pavel Machek <pavel@....cz>
To:     trivial@...nel.org, mark@...heh.com, jlbec@...lplan.org,
        joseph.qi@...ux.alibaba.com, ocfs2-devel@....oracle.com,
        linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH] ocfs2: fix unbalanced locking


Based on what fails, function can return with nfs_sync_rwlock either
locked or unlocked. That can not be right.

Always return with lock unlocked on error.

Signed-off-by: Pavel Machek (CIP) <pavel@...x.de>

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 751bc4dc7466..8e3a369086db 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2871,9 +2871,15 @@ int ocfs2_nfs_sync_lock(struct ocfs2_super *osb, int ex)
 
 	status = ocfs2_cluster_lock(osb, lockres, ex ? LKM_EXMODE : LKM_PRMODE,
 				    0, 0);
-	if (status < 0)
+	if (status < 0) {
 		mlog(ML_ERROR, "lock on nfs sync lock failed %d\n", status);
 
+		if (ex)
+			up_write(&osb->nfs_sync_rwlock);
+		else
+			up_read(&osb->nfs_sync_rwlock);
+	}
+
 	return status;
 }
 

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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