[PATCH] remove unnecesary while loop in ext2_xattr_get

[PATCH] remove unnecesary while loop in ext2_xattr_get

[crosslonelyover]

Hi,
     In ext2_xattr_get, we'll check the xattr entry one 
by one in the following loop:
         entry = FIRST_ENTRY(bh);
         while (!IS_LAST_ENTRY(entry)) {
                 struct ext2_xattr_entry *next =
                         EXT2_XATTR_NEXT(entry);
                 if ((char *)next >= end)
                         goto bad_block;
                 if (name_index == entry->e_name_index &&
                     name_len == entry->e_name_len &&
                     memcmp(name, entry->e_name, name_len) == 0)
                         goto found;
                 entry = next;
         }
We can only execute the code immediately following 
the loop when !IS_LAST_ENTRY(entry) is true. So the
followed while loop seems unnecessary. I think we can
remove it.
      Following is my patch. It's against 2.6.35-rc4.
Please check it.


Signed-off-by: Wang Sheng-Hui <crosslonelyover@gmail.com>
---
 fs/ext2/xattr.c |    9 +--------
 1 files changed, 1 insertions(+), 8 deletions(-)

diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 0b94d61..a6bccdb 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -201,14 +201,7 @@ bad_block:	ext2_error(inode->i_sb, "ext2_xattr_get",
 			goto found;
 		entry = next;
 	}
-	/* Check the remaining name entries */
-	while (!IS_LAST_ENTRY(entry)) {
-		struct ext2_xattr_entry *next =
-			EXT2_XATTR_NEXT(entry);
-		if ((char *)next >= end)
-			goto bad_block;
-		entry = next;
-	}
+
 	if (ext2_xattr_cache_insert(bh))
 		ea_idebug(inode, "cache insert failed");
 	error = -ENODATA;
-- 
1.7.1.1

Re: [PATCH] remove unnecesary while loop in ext2_xattr_get

[Dan Carpenter]

On Mon, Jul 12, 2010 at 11:09:09PM +0800, crosslonelyover wrote:
> Hi,
>      In ext2_xattr_get, we'll check the xattr entry one 
> by one in the following loop:
>          entry = FIRST_ENTRY(bh);
>          while (!IS_LAST_ENTRY(entry)) {
>                  struct ext2_xattr_entry *next =
>                          EXT2_XATTR_NEXT(entry);
>                  if ((char *)next >= end)
>                          goto bad_block;
>                  if (name_index == entry->e_name_index &&
>                      name_len == entry->e_name_len &&
>                      memcmp(name, entry->e_name, name_len) == 0)
>                          goto found;
>                  entry = next;
>          }
> We can only execute the code immediately following 
> the loop when !IS_LAST_ENTRY(entry) is true. So the
> followed while loop seems unnecessary. I think we can
> remove it.
>       Following is my patch. It's against 2.6.35-rc4.
> Please check it.
> 

Yes.  This is dead code.  This stuff is from the days before git
so we'll never know who to blame for it.

Reviewed-by: Dan Carpenter <error27@gmail.com>

regards,
dan carpenter