[PATCH 2/4]ext4: Remove unneeded BUG_ON() in ext4_move_extents()

[PATCH 2/4]ext4: Remove unneeded BUG_ON() in ext4_move_extents()

[Akira Fujita]

ext4: Remove unneeded BUG_ON() in ext4_move_extents()

From: Akira Fujita <a-fujita@rs.jp.nec.com>

ext4_move_extents() checks with BUG_ON() whether
the exchanged blocks count accords with request blocks count.
But, if the target range (orig_start + len) includes sparse block(s),
'moved_len' (exchanged blocks count) does not accord with
'len' (request blocks count),
since sparse block is not counted in 'moved_len'.
Therefore we hit BUG_ON(), though it succeeded.

Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
---
 fs/ext4/move_extent.c |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 60ed567..643156a 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -1323,8 +1323,5 @@ out2:
 	if (ret)
 		return ret;

-	/* All of the specified blocks must be exchanged in succeed */
-	BUG_ON(*moved_len != len);

Re: [PATCH 2/4]ext4: Remove unneeded BUG_ON() in ext4_move_extents()

[Peng Tao]

2009/9/2 Akira Fujita <a-fujita@rs.jp.nec.com>:
> ext4: Remove unneeded BUG_ON() in ext4_move_extents()
>
> From: Akira Fujita <a-fujita@rs.jp.nec.com>
>
> ext4_move_extents() checks with BUG_ON() whether
> the exchanged blocks count accords with request blocks count.
> But, if the target range (orig_start + len) includes sparse block(s),
> 'moved_len' (exchanged blocks count) does not accord with
> 'len' (request blocks count),
> since sparse block is not counted in 'moved_len'.
> Therefore we hit BUG_ON(), though it succeeded.
I can confirm the bug in my test cases too.

>
> Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
> ---
>  fs/ext4/move_extent.c |    3 ---
>  1 files changed, 0 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
> index 60ed567..643156a 100644
> --- a/fs/ext4/move_extent.c
> +++ b/fs/ext4/move_extent.c
> @@ -1323,8 +1323,5 @@ out2:
>        if (ret)
>                return ret;
>
> -       /* All of the specified blocks must be exchanged in succeed */
> -       BUG_ON(*moved_len != len);
> -
>        return 0;
>  }
> --
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>



-- 
Cheers,
Peng Tao
State Key Laboratory of Networking and Switching Technology
Beijing Univ. of Posts and Telecoms.
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Re: [PATCH 2/4]ext4: Remove unneeded BUG_ON() in ext4_move_extents()

[Akira Fujita]

Hi Peng,
Peng Tao wrote:
> 2009/9/2 Akira Fujita <a-fujita@rs.jp.nec.com>:
>> ext4: Remove unneeded BUG_ON() in ext4_move_extents()
>>
>> From: Akira Fujita <a-fujita@rs.jp.nec.com>
>>
>> ext4_move_extents() checks with BUG_ON() whether
>> the exchanged blocks count accords with request blocks count.
>> But, if the target range (orig_start + len) includes sparse block(s),
>> 'moved_len' (exchanged blocks count) does not accord with
>> 'len' (request blocks count),
>> since sparse block is not counted in 'moved_len'.
>> Therefore we hit BUG_ON(), though it succeeded.
> I can confirm the bug in my test cases too.

I am looking into the issues you reported before:
http://marc.info/?l=linux-ext4&m=124975192830024&w=2
http://marc.info/?l=linux-ext4&m=124992522305319&w=2

When I send patches to the list, please review and test them.

Regards,
Akira Fujita

Re: [PATCH 2/4]ext4: Remove unneeded BUG_ON() in ext4_move_extents()

[Theodore Tso]

On Wed, Sep 02, 2009 at 12:17:57PM +0900, Akira Fujita wrote:
> ext4: Remove unneeded BUG_ON() in ext4_move_extents()
> 
> From: Akira Fujita <a-fujita@rs.jp.nec.com>
> 
> ext4_move_extents() checks with BUG_ON() whether
> the exchanged blocks count accords with request blocks count.
> But, if the target range (orig_start + len) includes sparse block(s),
> 'moved_len' (exchanged blocks count) does not accord with
> 'len' (request blocks count),
> since sparse block is not counted in 'moved_len'.
> Therefore we hit BUG_ON(), though it succeeded.

Added to the ext4 patch queue.

					- Ted