[PATCH] dcache: fix locking bug in __dentry_path()

[Denys Vlasenko]

If given buffer size is zero, we forget to rcu_read_unlock()
on error path.

Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
---
 fs/dcache.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index cb4a106..24a01fc 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3127,8 +3127,11 @@ restart:
 	end = buf + buflen;
 	len = buflen;
 	prepend(&end, &len, "\0", 1);
-	if (buflen < 1)
+	if (buflen < 1) {
+		if (!(seq & 1))
+			rcu_read_unlock();
 		goto Elong;
+	}
 	/* Get '/' right */
 	retval = end-1;
 	*retval = '/';
-- 
1.8.1.4

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