* [PATCH] Ext4: remove a useless check for the function ext4_data_block_valid
@ 2013-01-26 22:57 Wang Shilong
2013-01-26 15:38 ` Theodore Ts'o
0 siblings, 1 reply; 6+ messages in thread
From: Wang Shilong @ 2013-01-26 22:57 UTC (permalink / raw)
To: tytso; +Cc: linux-ext4
From: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Because it is no doubt 'start_blk + count < start_blk' always comes to
false. It is useless to have this check,remove it.
Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
---
fs/ext4/block_validity.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 3f11656..5ffce82 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -226,7 +226,6 @@ int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
struct rb_node *n = sbi->system_blks.rb_node;
if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
- (start_blk + count < start_blk) ||
(start_blk + count > ext4_blocks_count(sbi->s_es))) {
sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
return 0;
-- 1.7.11.7
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] Ext4: remove a useless check for the function ext4_data_block_valid
2013-01-26 22:57 [PATCH] Ext4: remove a useless check for the function ext4_data_block_valid Wang Shilong
@ 2013-01-26 15:38 ` Theodore Ts'o
2013-01-28 0:46 ` Wang Shilong
0 siblings, 1 reply; 6+ messages in thread
From: Theodore Ts'o @ 2013-01-26 15:38 UTC (permalink / raw)
To: Wang Shilong; +Cc: linux-ext4
On Sat, Jan 26, 2013 at 02:57:59PM -0800, Wang Shilong wrote:
> From: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
>
> Because it is no doubt 'start_blk + count < start_blk' always comes to
> false. It is useless to have this check,remove it.
Actually, it can be true --- if start_blk + count (which are both
unsigned integers) overflows....
- Ted
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Ext4: remove a useless check for the function ext4_data_block_valid
2013-01-26 15:38 ` Theodore Ts'o
@ 2013-01-28 0:46 ` Wang Shilong
2013-01-27 12:38 ` Theodore Ts'o
0 siblings, 1 reply; 6+ messages in thread
From: Wang Shilong @ 2013-01-28 0:46 UTC (permalink / raw)
To: Theodore Ts'o; +Cc: linux-ext4
> On Sat, Jan 26, 2013 at 02:57:59PM -0800, Wang Shilong wrote:
>> From: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
>>
>> Because it is no doubt 'start_blk + count < start_blk' always comes to
>> false. It is useless to have this check,remove it.
> Actually, it can be true --- if start_blk + count (which are both
> unsigned integers) overflows....
Yeah,you are right....
I am sorry,I miss the overflow condition...
> - Ted
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] Ext4: remove a useless check for the function ext4_data_block_valid
2013-01-28 0:46 ` Wang Shilong
@ 2013-01-27 12:38 ` Theodore Ts'o
0 siblings, 0 replies; 6+ messages in thread
From: Theodore Ts'o @ 2013-01-27 12:38 UTC (permalink / raw)
To: Wang Shilong; +Cc: linux-ext4
On Sun, Jan 27, 2013 at 04:46:29PM -0800, Wang Shilong wrote:
> > Actually, it can be true --- if start_blk + count (which are both
> > unsigned integers) overflows....
> Yeah,you are right....
> I am sorry,I miss the overflow condition...
We added it because we saw a crash that was a caused by an overflow,
if memory serves correctly. Or maybe it was a mysterious data or file
system corruption that was incredibly painful to find.
Fun trivia fact: the European Space Agency had the Ariane 5 rocket
explode on its maiden flight due to a integer overflow bug.
- Ted
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] Ext4: remove a useless check for the function ext4_data_block_valid
@ 2012-01-26 22:55 Wang Shilong
0 siblings, 0 replies; 6+ messages in thread
From: Wang Shilong @ 2012-01-26 22:55 UTC (permalink / raw)
To: tytso; +Cc: linux-ext4
From: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Because it is no doubt 'start_blk + count < start_blk' always comes to
false. It is useless to have this check,remove it.
Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
---
fs/ext4/block_validity.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 3f11656..5ffce82 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -226,7 +226,6 @@ int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
struct rb_node *n = sbi->system_blks.rb_node;
if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
- (start_blk + count < start_blk) ||
(start_blk + count > ext4_blocks_count(sbi->s_es))) {
sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
return 0;
-- 1.7.11.7
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH] Ext4: remove a useless check for the function ext4_data_block_valid
@ 2011-01-26 22:45 Wang Shilong
0 siblings, 0 replies; 6+ messages in thread
From: Wang Shilong @ 2011-01-26 22:45 UTC (permalink / raw)
To: tytso; +Cc: linux-ext4
From: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Because it is no doubt 'start_blk + count < start_blk' always comes to
false. It is useless to have this check,remove it.
Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
---
fs/ext4/block_validity.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 3f11656..5ffce82 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -226,7 +226,6 @@ int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
struct rb_node *n = sbi->system_blks.rb_node;
if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
- (start_blk + count < start_blk) ||
(start_blk + count > ext4_blocks_count(sbi->s_es))) {
sbi->s_es->s_last_error_block = cpu_to_le64(start_blk);
return 0;
-- 1.7.11.7
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-01-27 12:38 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-01-26 22:57 [PATCH] Ext4: remove a useless check for the function ext4_data_block_valid Wang Shilong
2013-01-26 15:38 ` Theodore Ts'o
2013-01-28 0:46 ` Wang Shilong
2013-01-27 12:38 ` Theodore Ts'o
-- strict thread matches above, loose matches on Subject: below --
2012-01-26 22:55 Wang Shilong
2011-01-26 22:45 Wang Shilong
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).