jffs2: unlock f->sem on error in jffs2_new_inode()

If jffs2_new_inode() succeeds, it returns with f->sem held, and the caller
is responsible for releasing the lock.  If it fails, it still returns with
the lock held, but the caller won't release the lock, which will lead to
deadlock.

Fix it by releasing the lock in jffs2_new_inode() on error.
Signed-off-by: NWang Guoli <andy.wangguoli@huawei.com>
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Wang Guoli <andy.wangguoli@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
[Brian: not marked for stable; no one observed deadlock, and I don't
        think it can happen here]
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>

fs/jffs2/fs.c

@@ -457,12 +457,14 @@ struct inode *jffs2_new_inode (struct inode *dir_i, umode_t mode, struct jffs2_r
 	   The umask is only applied if there's no default ACL */
 	ret = jffs2_init_acl_pre(dir_i, inode, &mode);
 	if (ret) {
+		mutex_unlock(&f->sem);
 		make_bad_inode(inode);
 		iput(inode);
 		return ERR_PTR(ret);
 	}
 	ret = jffs2_do_new_inode (c, f, mode, ri);
 	if (ret) {
+		mutex_unlock(&f->sem);
 		make_bad_inode(inode);
 		iput(inode);
 		return ERR_PTR(ret);
@@ -479,6 +481,7 @@ struct inode *jffs2_new_inode (struct inode *dir_i, umode_t mode, struct jffs2_r
 	inode->i_size = 0;
 
 	if (insert_inode_locked(inode) < 0) {
+		mutex_unlock(&f->sem);
 		make_bad_inode(inode);
 		iput(inode);
 		return ERR_PTR(-EINVAL);