ext4: issue warning when bad inode found via ext4_lookup

I have a hand-crafted bad filesystem image which has corruption:

[root@inode ~]# ls mnt/dir
file1 file2 file3 file4 file5
[root@inode ~]# ls mnt/dir/file4
ls: cannot access mnt/dir/file4: No such file or directory [root@inode ~]# ls -l mnt/dir
ls: cannot access mnt/dir/file4: No such file or directory total 8
drwxr-xr-x 2 root root 1024 2007-09-04 13:36 file1 drwxr-xr-x 2 root root 1024 2007-09-04 13:36 file2 drwxr-xr-x 2 root root 1024 2007-09-04 13:36 file3
d????????? ? ? ? ? ? file4
drwxr-xr-x 2 root root 1024 2007-09-04 13:36 file5

e2fsck also knows it's corrupted:
Pass 2: Checking directory structure
Entry 'file4' in /dir (2049) has deleted/unused inode 13. Clear? no

Entry 'file4' in /dir (2049) has an incorrect filetype (was 2, should be 1). Fix? no

Pass 3: Checking directory connectivity
Unconnected directory inode 2053 (/dir/???)

BUT there are no kernel messages logged anywhere because ext4_read_inode silently makes a bad_inode in this case, so that stale NFS filehandles aren't noisy. However, when we encounter such a problem after a by-name lookup, I think a warning is appropriate, as it indicates filesystem corruption.

---

Index: linux-2.6.24-rc3/fs/ext4/namei.c
===================================================================
@@ -1050,6 +1050,9 @@ static struct dentry *ext4_lookup(struct
 			return ERR_PTR(-EACCES);
 
 		if (is_bad_inode(inode)) {
+			ext4_warning(inode->i_sb, __FUNCTION__,
+				     "bad inode %lu in dir #%lu",
+				     inode->i_ino, dir->i_ino);
 			iput(inode);
 			return ERR_PTR(-ENOENT);
 		}