2010-07-12 15:08:55

by shenghui

Subject: [PATCH] remove unnecesary while loop in ext2_xattr_get

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 <[email protected]>
---
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

2010-07-12 16:42:12

by Dan Carpenter

Subject: Re: [PATCH] remove unnecesary while loop in ext2_xattr_get

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 <[email protected]>

regards,
dan carpenter