tmpfs: fix uninitialized return value in shmem_link

mainline inclusion
from mainline-v5.0-rc8
commit 29b00e609960
category: bugfix
bugzilla: 10938
CVE: NA

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

When we made the shmem_reserve_inode call in shmem_link conditional, we
forgot to update the declaration for ret so that it always has a known
value.  Dan Carpenter pointed out this deficiency in the original patch.

Fixes: 1062af920c07 ("tmpfs: fix link accounting when a tmpfile is linked in")
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Matej Kupljen <matej.kupljen@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Nzhong jiang <zhongjiang@huawei.com>
Reviewed-by: NJing Xiangfeng <jingxiangfeng@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

mm/shmem.c

@@ -2895,7 +2895,7 @@ static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
 {
 	struct inode *inode = d_inode(old_dentry);
-	int ret;
+	int ret = 0;
 
 	/*
 	 * No ordinary (disk based) filesystem counts links as inodes;