fs/namei: fix possible uninitialized use of inode

commit 12f8ad4b0533d9212cb1d5e58ed73d2170114785 introduces a path which might lead to uninitialized use.

fs/namei.c: In function ‘walk_component’:
fs/namei.c:1293:6: warning: ‘inode’ may be used uninitialized in this function [-Wuninitialized] fs/namei.c:1308:16: note: ‘inode’ was declared here

The commit mentioned above removed this:

	*inode = nd->inode;

And now there's a possible that path looks like this:
...
1147 dentry = __d_lookup_rcu(parent, name, &seq, nd->inode);
1148 if (!dentry)
1149 goto unlazy;
...
1187 unlazy:
...
1204 if (unlikely(status <= 0)) {
1205 if (status < 0) {
1206 dput(dentry);
1207 return status;
1208 }
1209 if (!d_invalidate(dentry)) {
1210 dput(dentry);
1211 goto need_lookup;
1212 }
1213 }

So we might return 0 to walk_component, which does this compare right after check the return code from do_lookup:

  1312:		if (!inode) {

---
 fs/namei.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index f9e883c..f77b69b 100644
@@ -1295,7 +1295,7 @@ static inline int should_follow_link(struct inode *inode, int follow)
 static inline int walk_component(struct nameidata *nd, struct path *path,
 		struct qstr *name, int type, int follow)
 {
-	struct inode *inode;
+	struct inode *inode = NULL;
 	int err;
 	/*
 	 * "." and ".." are special - ".." especially so because it has

1.7.10