[PATCH 6/6] GFS2: fix d_splice_alias() misuses

From: Steven Whitehouse
Date: Mon Sep 15 2014 - 05:33:21 EST


From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx # v3.14+
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Whitehouse <swhiteho@xxxxxxxxxx>

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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