ext2: Fix error handling on inode bitmap corruption

When insert_inode_locked() fails in ext2_new_inode() it most likely means inode
bitmap got corrupted and we allocated again inode which is already in use. Also
doing unlock_new_inode() during error recovery is wrong since the inode does
not have I_NEW set. Fix the problem by informing about filesystem error and
jumping to fail: (instead of fail_drop:) which doesn't call unlock_new_inode().
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext2/ialloc.c

@@ -573,8 +573,11 @@ struct inode *ext2_new_inode(struct inode *dir, int mode,
 	inode->i_generation = sbi->s_next_generation++;
 	spin_unlock(&sbi->s_next_gen_lock);
 	if (insert_inode_locked(inode) < 0) {
-		err = -EINVAL;
-		goto fail_drop;
+		ext2_error(sb, "ext2_new_inode",
+			   "inode number already in use - inode=%lu",
+			   (unsigned long) ino);
+		err = -EIO;
+		goto fail;
 	}
 
 	dquot_initialize(inode);