linux-kernel - [PATCH 3.16.y-ckt 032/142] NFSv4: Fix a dentry leak on alias use

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Message-Id: <1458643271-4227-33-git-send-email-luis.henriques@canonical.com>
Date:	Tue, 22 Mar 2016 10:39:21 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Benjamin Coddington <bcodding@...hat.com>,
	Trond Myklebust <trond.myklebust@...marydata.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 032/142] NFSv4: Fix a dentry leak on alias use

3.16.7-ckt26 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Benjamin Coddington <bcodding@...hat.com>

commit d9dfd8d741683347ee159d25f5b50c346a0df557 upstream.

In the case where d_add_unique() finds an appropriate alias to use it will
have already incremented the reference count.  An additional dget() to swap
the open context's dentry is unnecessary and will leak a reference.

Signed-off-by: Benjamin Coddington <bcodding@...hat.com>
Fixes: 275bb307865a3 ("NFSv4: Move dentry instantiation into the NFSv4-...")
Signed-off-by: Trond Myklebust <trond.myklebust@...marydata.com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 fs/nfs/nfs4proc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index cdbc0599664d..864b3214cc89 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2243,9 +2243,9 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata,
 		dentry = d_add_unique(dentry, igrab(state->inode));
 		if (dentry == NULL) {
 			dentry = opendata->dentry;
-		} else if (dentry != ctx->dentry) {
+		} else {
 			dput(ctx->dentry);
-			ctx->dentry = dget(dentry);
+			ctx->dentry = dentry;
 		}
 		nfs_set_verifier(dentry,
 				nfs_save_change_attribute(opendata->dir->d_inode));