From: Eric Sandeen <sandeen@redhat.com>
Date: Wed, 19 Dec 2007 12:53:06 -0600
Subject: [fs] ext3: error in ext3_lookup if corruption found
Message-id: 47696892.3020001@redhat.com
O-Subject: [RHEL 5.2 PATCH, updated] - error in ext3_lookup if corruption is found
Bugzilla: 181662

Bugzilla Bug 181662: Filesystem errors should be logged and not silently ignored

I have a hand-crafted bad filesystem image which has corruption replicating
that reported by the customer:

[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 ext3_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 an ext3_error is appropriate, as it indicates filesystem
corruption.

I discussed the patch w/ Andreas Dilger, who though it looked reasonable,
and I've sent it upstream to -mm, where Andrew says
"It's in my backlog somewhere - I'll get to it."

Signed-off-by: Eric Sandeen <sandeen@redhat.com>

Acked-by: Peter Staubach <staubach@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>

diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c
index e97619c..35590db 100644
--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -1027,6 +1027,11 @@ static struct dentry *ext3_lookup(struct inode * dir, struct dentry *dentry, str
 			return ERR_PTR(-EACCES);
 
 		if (is_bad_inode(inode)) {
+			/* if bad because unlinked, something has gone wrong */
+			if (!inode->i_nlink && printk_ratelimit())
+				ext3_error(inode->i_sb, __FUNCTION__,
+					    "unlinked inode %lu in dir #%lu",
+					     inode->i_ino, dir->i_ino);
 			iput(inode);
 			return ERR_PTR(-ENOENT);
 		}