[PATCH 3.16 296/357] GFS2: fix d_splice_alias() misuses

From: Greg Kroah-Hartman
Date: Fri Oct 03 2014 - 19:47:46 EST


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

------------------

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit cfb2f9d5c921e38b0f12bb26fed10b877664444d upstream.

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.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Whitehouse <swhiteho@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/gfs2/inode.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -626,8 +626,10 @@ static int gfs2_create_inode(struct inod
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)) {
@@ -854,7 +856,6 @@ static struct dentry *__gfs2_lookup(stru

d = d_splice_alias(inode, dentry);
if (IS_ERR(d)) {
- iput(inode);
gfs2_glock_dq_uninit(&gh);
return d;
}


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/