[PATCH] ext3 : Remove redundant condition in ext3_free_blocks_sb()

[PATCH] ext3 : Remove redundant condition in ext3_free_blocks_sb()

[Manish Katiyar]

For two unsigned values the check "block+count < block"  is always
false. Thus the below patch removes that condition.

=============================================================

Signed-off-by: Manish Katiyar <mkatiyar@gmail.com>

--- a/fs/ext3/balloc.c  2008-05-11 23:54:40.000000000 +0530
+++ b/fs/ext3/balloc.c  2008-06-01 00:05:25.000000000 +0530
@@ -493,7 +493,6 @@
        sbi = EXT3_SB(sb);
        es = sbi->s_es;
        if (block < le32_to_cpu(es->s_first_data_block) ||
-           block + count < block ||
            block + count > le32_to_cpu(es->s_blocks_count)) {
                ext3_error (sb, "ext3_free_blocks",
                            "Freeing blocks not in datazone - "

=============================================================

-- 
Thanks & Regards,
********************************************
Manish Katiyar ( http://mkatiyar.googlepages.com )
3rd Floor, Fair Winds Block
EGL Software Park
Off Intermediate Ring Road
Bangalore 560071, India
***********************************************

Re: [PATCH] ext3 : Remove redundant condition in ext3_free_blocks_sb()

[Al Viro]

On Sun, Jun 01, 2008 at 12:26:41AM +0530, Manish Katiyar wrote:
> For two unsigned values the check "block+count < block"  is always
> false. Thus the below patch removes that condition.

Really?  Always?

	unsigned block = 1;
	unsigned count = ~0U;

What will be the value and type of block + count?  What will be the
value of block + count < block?

Re: [PATCH] ext3 : Remove redundant condition in ext3_free_blocks_sb()

[Manish Katiyar]

On Sun, Jun 1, 2008 at 12:35 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Sun, Jun 01, 2008 at 12:26:41AM +0530, Manish Katiyar wrote:
>> For two unsigned values the check "block+count < block"  is always
>> false. Thus the below patch removes that condition.
>
> Really?  Always?
>
>        unsigned block = 1;
>        unsigned count = ~0U;
>
> What will be the value and type of block + count?  What will be the
> value of block + count < block?

Oooops....my bad, but I doubt if we pass such values in ext* code anywhere.

>



-- 
Thanks & Regards,
********************************************
Manish Katiyar ( http://mkatiyar.googlepages.com )
3rd Floor, Fair Winds Block
EGL Software Park
Off Intermediate Ring Road
Bangalore 560071, India
***********************************************

Re: [PATCH] ext3 : Remove redundant condition in ext3_free_blocks_sb()

[Matthew Wilcox]

On Sun, Jun 01, 2008 at 12:40:32AM +0530, Manish Katiyar wrote:
> Oooops....my bad, but I doubt if we pass such values in ext* code anywhere.

If we have a corrupt filesystem, we can pass total garbage here.  This
check prevents that from corrupting the filesystem further.  Patch NAKed
with extreme prejudice.

-- 
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"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."