ext3/ext4: orphan list corruption due bad inode

After ext3 orphan list check has been added into ext3_destroy_inode()
(please see my previous patch) the following situation has been detected:

 EXT3-fs warning (device sda6): ext3_unlink: Deleting nonexistent file (37901290), 0
 Inode 00000101a15b7840: orphan list check failed!
 00000773 6f665f00 74616d72 00000573 65725f00 06737270 66000000 616d726f
...
 Call Trace: [<ffffffff80211ea9>] ext3_destroy_inode+0x79/0x90
  [<ffffffff801a2b16>] sys_unlink+0x126/0x1a0
  [<ffffffff80111479>] error_exit+0x0/0x81
  [<ffffffff80110aba>] system_call+0x7e/0x83

First messages said that unlinked inode has i_nlink=0, then ext3_unlink()
adds this inode into orphan list.

Second message means that this inode has not been removed from orphan list.
 Inode dump has showed that i_fop = &bad_file_ops and it can be set in
make_bad_inode() only.  Then I've found that ext3_read_inode() can call
make_bad_inode() without any error/warning messages, for example in the
following case:

...
        if (inode->i_nlink == 0) {
                if (inode->i_mode == 0 ||
                    !(EXT3_SB(inode->i_sb)->s_mount_state & EXT3_ORPHAN_FS)) {
                        /* this inode is deleted */
                        brelse (bh);
                        goto bad_inode;
...

Bad inode can live some time, ext3_unlink can add it to orphan list, but
ext3_delete_inode() do not deleted this inode from orphan list.  As result
we can have orphan list corruption detected in ext3_destroy_inode().

However it is not clear for me how to fix this issue correctly.

As far as i see is_bad_inode() is called after iget() in all places
excluding ext3_lookup() and ext3_get_parent().  I believe it makes sense to
add bad inode check to these functions too and call iput if bad inode
detected.

Signed-off-by:	Vasily Averin <vvs@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 2811e5720ad0..2de339dd7554 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1017,6 +1017,11 @@ static struct dentry *ext4_lookup(struct inode * dir, struct dentry *dentry, str
 
                 if (!inode)
                         return ERR_PTR(-EACCES);
+
+                if (is_bad_inode(inode)) {
+                        iput(inode);
+                        return ERR_PTR(-ENOENT);
+                }
         }
         return d_splice_alias(inode, dentry);
 }
@@ -1052,6 +1057,11 @@ struct dentry *ext4_get_parent(struct dentry *child)
         if (!inode)
                 return ERR_PTR(-EACCES);
 
+        if (is_bad_inode(inode)) {
+                iput(inode);
+                return ERR_PTR(-ENOENT);
+        }
+
         parent = d_alloc_anon(inode);
         if (!parent) {
                 iput(inode);