Re: 2.6.29-git: cannot mount ext4/loop

[Thiemo Nagel]

Theodore Tso wrote:
> On Thu, Apr 02, 2009 at 05:18:39PM +0200, Thiemo Nagel wrote:
> > Theodore Tso wrote:
> > > On Thu, Apr 02, 2009 at 03:30:26PM +0200, Thiemo Nagel wrote:
> > > > When I added the block range checks, initially I was assuming that
> > > > when EXTENTS_FL is not set, the inode->i_data *always* contains
> > > > references to further blocks.  Ted showed me wrong and added the condition
> > > >
> > > > 	ISREG() || ISDIR() || ( ISLNK() && !is_fast_symlink() )
> > > >
> > > > before that assumption can be made.  But maybe we need some further
> > > > restraints?
> > > It's a endian-problem; we're missing le32_to_cpu() in that patch.
> > > Sparc is big-endian. 
> > Sorry for that.
>
> Could you also fix the types?  bref should have a type of __le32, not
> unsigned int, and when you pass in the reference to
> __ext4_check_blockref(), there was an inappropriate cast to unsigned
> int which hid kernel's natural type checking to catch these sorts of
> problems.

So I was really asking for things to go wrong...  :-(
I hope the attached patch handles conversion and types in the right way. 
 It's compile-tested only, the current ext4 tree crashes my machine.

Kind regards,

Thiemo
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 98e289a..849e099 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -372,16 +372,16 @@ static int ext4_block_to_path(struct inode *inode,
 }
 
 static int __ext4_check_blockref(const char *function, struct inode *inode,
-				 unsigned int *p, unsigned int max) {
+				 __le32 *p, unsigned int max) {
 
 	unsigned int maxblocks = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es);
-	unsigned int *bref = p;
+	__le32 *bref = p;
 	while (bref < p+max) {
-		if (unlikely(*bref >= maxblocks)) {
+		if (unlikely(le32_to_cpu(*bref) >= maxblocks)) {
 			ext4_error(inode->i_sb, function,
 				   "block reference %u >= max (%u) "
 				   "in inode #%lu, offset=%d",
-				   *bref, maxblocks,
+				   le32_to_cpu(*bref), maxblocks,
 				   inode->i_ino, (int)(bref-p));
  			return -EIO;
  		}
@@ -392,7 +392,7 @@ static int __ext4_check_blockref(const char *function, struct inode *inode,
 
 
 #define ext4_check_indirect_blockref(inode, bh)                         \
-        __ext4_check_blockref(__func__, inode, (__le32 *)(bh)->b_data,  \
+        __ext4_check_blockref(__func__, inode, (bh)->b_data,            \
 			      EXT4_ADDR_PER_BLOCK((inode)->i_sb))
 
 #define ext4_check_inode_blockref(inode)                                \