linux-kernel - [PATCH 6/6] GFS2: fix d_splice

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Date:	Mon, 15 Sep 2014 10:32:48 +0100
From:	Steven Whitehouse <swhiteho@...hat.com>
To:	linux-kernel@...r.kernel.org, cluster-devel@...hat.com
Cc:	Al Viro <viro@...IV.linux.org.uk>, stable@...r.kernel.org.#.v3.14+,
	Al Viro <viro@...IV.linux.org.uk>,
	Steven Whitehouse <swhiteho@...hat.com>
Subject: [PATCH 6/6] GFS2: fix d_splice_alias() misuses

From: Al Viro <viro@...IV.linux.org.uk>

Callers of d_splice_alias(dentry, inode) don't need iput(), neither
on success nor on failure.  Either the reference to inode is stored
in a previously negative dentry, or it's dropped.  In either case
inode reference the caller used to hold is consumed.

__gfs2_lookup() does iput() in case when d_splice_alias() has failed.
Double iput() if we ever hit that.  And gfs2_create_inode() ends up
not only with double iput(), but with link count dropped to zero - on
an inode it has just found in directory.

Cc: stable@...r.kernel.org # v3.14+
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Steven Whitehouse <swhiteho@...hat.com>

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 9317ddc..fc8ac2e 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -626,8 +626,10 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	if (!IS_ERR(inode)) {
 		d = d_splice_alias(inode, dentry);
 		error = PTR_ERR(d);
-		if (IS_ERR(d))
+		if (IS_ERR(d)) {
+			inode = ERR_CAST(d);
 			goto fail_gunlock;
+		}
 		error = 0;
 		if (file) {
 			if (S_ISREG(inode->i_mode)) {
@@ -856,7 +858,6 @@ static struct dentry *__gfs2_lookup(struct inode *dir, struct dentry *dentry,
 
 	d = d_splice_alias(inode, dentry);
 	if (IS_ERR(d)) {
-		iput(inode);
 		gfs2_glock_dq_uninit(&gh);
 		return d;
 	}
-- 
1.8.3.1

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