[PATCH] block: fix max discard sectors limit

[PATCH] block: fix max discard sectors limit

[Namjae Jeon]

From: Namjae Jeon <namjae.jeon@samsung.com>

linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
(block: add plug for blkdev_issue_discard )

For example,
1) DISCARD rq-1 with size size 4GB
2) DISCARD rq-2 with size size 1GB

If these 2 discard requests get merged, final request size will be 5GB.

In this case, request's __data_len field may overflow as it can store
max 4GB(unsigned int).

This issue was observed while doing mkfs.f2fs on 5GB SD card:
https://lkml.org/lkml/2013/4/1/292

Info: sector size = 512
Info: total sectors = 11370496 (in 512bytes)
Info: zone aligned segment0 blkaddr: 512
[  257.789764] blk_update_request: bio idx 0 >= vcnt 0

mkfs process gets stuck in D state and I see the following in the dmesg:

[  257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081
[  257.789764]   sector 4194304, nr/cnr 2981888/4294959104
[  257.789764]   bio df3840c0, biotail df3848c0, buffer   (null), len
1526726656
[  257.789764] blk_update_request: bio idx 0 >= vcnt 0
[  257.794921] request botched: dev mmcblk0: type=1, flags=122c8081
[  257.794921]   sector 4194304, nr/cnr 2981888/4294959104
[  257.794921]   bio df3840c0, biotail df3848c0, buffer   (null), len
1526726656

This patch fixes this issue.

Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Vivek Trivedi <t.vivek@samsung.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
---
 include/linux/blkdev.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 07aa5f6..ff636bd 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -844,7 +844,7 @@ static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
 						     unsigned int cmd_flags)
 {
 	if (unlikely(cmd_flags & REQ_DISCARD))
-		return q->limits.max_discard_sectors;
+		return min(q->limits.max_discard_sectors, UINT_MAX >> 9);
 
 	if (unlikely(cmd_flags & REQ_WRITE_SAME))
 		return q->limits.max_write_same_sectors;
-- 
1.7.9.5

Re: [PATCH] block: fix max discard sectors limit

[James Bottomley]

On Tue, 2013-04-23 at 22:06 +0900, Namjae Jeon wrote:
> From: Namjae Jeon <namjae.jeon@samsung.com>

Hey, it's very impolite to send a patch I just gave you as a suggestion
to fix the issue under your own authorship.

What we need to know is has this been tested ... there's no tested-by
tags (and there also should really be a reported by).

James

> linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
> commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
> (block: add plug for blkdev_issue_discard )
> 
> For example,
> 1) DISCARD rq-1 with size size 4GB
> 2) DISCARD rq-2 with size size 1GB
> 
> If these 2 discard requests get merged, final request size will be 5GB.
> 
> In this case, request's __data_len field may overflow as it can store
> max 4GB(unsigned int).
> 
> This issue was observed while doing mkfs.f2fs on 5GB SD card:
> https://lkml.org/lkml/2013/4/1/292
> 
> Info: sector size = 512
> Info: total sectors = 11370496 (in 512bytes)
> Info: zone aligned segment0 blkaddr: 512
> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> 
> mkfs process gets stuck in D state and I see the following in the dmesg:
> 
> [  257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081
> [  257.789764]   sector 4194304, nr/cnr 2981888/4294959104
> [  257.789764]   bio df3840c0, biotail df3848c0, buffer   (null), len
> 1526726656
> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> [  257.794921] request botched: dev mmcblk0: type=1, flags=122c8081
> [  257.794921]   sector 4194304, nr/cnr 2981888/4294959104
> [  257.794921]   bio df3840c0, biotail df3848c0, buffer   (null), len
> 1526726656
> 
> This patch fixes this issue.
> 
> Reported-by: Max Filippov <jcmvbkbc@gmail.com>
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: Vivek Trivedi <t.vivek@samsung.com>
> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
> Cc: Shaohua Li <shli@kernel.org>
> Cc: Kent Overstreet <koverstreet@google.com>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: <stable@vger.kernel.org>
> ---
>  include/linux/blkdev.h |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 07aa5f6..ff636bd 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -844,7 +844,7 @@ static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
>  						     unsigned int cmd_flags)
>  {
>  	if (unlikely(cmd_flags & REQ_DISCARD))
> -		return q->limits.max_discard_sectors;
> +		return min(q->limits.max_discard_sectors, UINT_MAX >> 9);
>  
>  	if (unlikely(cmd_flags & REQ_WRITE_SAME))
>  		return q->limits.max_write_same_sectors;

Re: [PATCH] block: fix max discard sectors limit

[Max Filippov]

On Tue, Apr 23, 2013 at 5:42 PM, James Bottomley
<jbottomley@parallels.com> wrote:
> On Tue, 2013-04-23 at 22:06 +0900, Namjae Jeon wrote:
>> From: Namjae Jeon <namjae.jeon@samsung.com>
>
> Hey, it's very impolite to send a patch I just gave you as a suggestion
> to fix the issue under your own authorship.
>
> What we need to know is has this been tested ... there's no tested-by
> tags (and there also should really be a reported by).

I can confirm that this patch also fixes the original issue.
Tested-by: Max Filippov <jcmvbkbc@gmail.com>

>> linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
>> commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
>> (block: add plug for blkdev_issue_discard )
>>
>> For example,
>> 1) DISCARD rq-1 with size size 4GB
>> 2) DISCARD rq-2 with size size 1GB
>>
>> If these 2 discard requests get merged, final request size will be 5GB.
>>
>> In this case, request's __data_len field may overflow as it can store
>> max 4GB(unsigned int).
>>
>> This issue was observed while doing mkfs.f2fs on 5GB SD card:
>> https://lkml.org/lkml/2013/4/1/292
>>
>> Info: sector size = 512
>> Info: total sectors = 11370496 (in 512bytes)
>> Info: zone aligned segment0 blkaddr: 512
>> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
>>
>> mkfs process gets stuck in D state and I see the following in the dmesg:
>>
>> [  257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081
>> [  257.789764]   sector 4194304, nr/cnr 2981888/4294959104
>> [  257.789764]   bio df3840c0, biotail df3848c0, buffer   (null), len
>> 1526726656
>> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
>> [  257.794921] request botched: dev mmcblk0: type=1, flags=122c8081
>> [  257.794921]   sector 4194304, nr/cnr 2981888/4294959104
>> [  257.794921]   bio df3840c0, biotail df3848c0, buffer   (null), len
>> 1526726656
>>
>> This patch fixes this issue.
>>
>> Reported-by: Max Filippov <jcmvbkbc@gmail.com>
>> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
>> Signed-off-by: Vivek Trivedi <t.vivek@samsung.com>
>> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
>> Cc: Shaohua Li <shli@kernel.org>
>> Cc: Kent Overstreet <koverstreet@google.com>
>> Cc: Tejun Heo <tj@kernel.org>
>> Cc: Jens Axboe <axboe@kernel.dk>
>> Cc: <stable@vger.kernel.org>
>> ---
>>  include/linux/blkdev.h |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
>> index 07aa5f6..ff636bd 100644
>> --- a/include/linux/blkdev.h
>> +++ b/include/linux/blkdev.h
>> @@ -844,7 +844,7 @@ static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
>>                                                    unsigned int cmd_flags)
>>  {
>>       if (unlikely(cmd_flags & REQ_DISCARD))
>> -             return q->limits.max_discard_sectors;
>> +             return min(q->limits.max_discard_sectors, UINT_MAX >> 9);
>>
>>       if (unlikely(cmd_flags & REQ_WRITE_SAME))
>>               return q->limits.max_write_same_sectors;

-- 
Thanks.
-- Max

Re: [PATCH] block: fix max discard sectors limit

[Jens Axboe]

On Tue, Apr 23 2013, Max Filippov wrote:
> On Tue, Apr 23, 2013 at 5:42 PM, James Bottomley
> <jbottomley@parallels.com> wrote:
> > On Tue, 2013-04-23 at 22:06 +0900, Namjae Jeon wrote:
> >> From: Namjae Jeon <namjae.jeon@samsung.com>
> >
> > Hey, it's very impolite to send a patch I just gave you as a suggestion
> > to fix the issue under your own authorship.
> >
> > What we need to know is has this been tested ... there's no tested-by
> > tags (and there also should really be a reported by).
> 
> I can confirm that this patch also fixes the original issue.
> Tested-by: Max Filippov <jcmvbkbc@gmail.com>

Goodie. Namjae, please re-send with properly attributed patch and I'll
get this applied.

-- 
Jens Axboe

Re: [PATCH] block: fix max discard sectors limit

[Namjae Jeon]

2013/4/23, James Bottomley <jbottomley@parallels.com>:
> On Tue, 2013-04-23 at 22:06 +0900, Namjae Jeon wrote:
>> From: Namjae Jeon <namjae.jeon@samsung.com>
>
> Hey, it's very impolite to send a patch I just gave you as a suggestion
> to fix the issue under your own authorship.
>
> What we need to know is has this been tested ... there's no tested-by
> tags (and there also should really be a reported by).
Sorry James, as I do not have the exact MMC on which the issue is reproduce.
So I just checked for sanity on my MMC - there was no issue.
But for exact issue fix it was mistake to not request for testing.
I will take care of this in future, for pushing such patches.
Thanks.
>
> James
>
>> linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
>> commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
>> (block: add plug for blkdev_issue_discard )
>>
>> For example,
>> 1) DISCARD rq-1 with size size 4GB
>> 2) DISCARD rq-2 with size size 1GB
>>
>> If these 2 discard requests get merged, final request size will be 5GB.
>>
>> In this case, request's __data_len field may overflow as it can store
>> max 4GB(unsigned int).
>>
>> This issue was observed while doing mkfs.f2fs on 5GB SD card:
>> https://lkml.org/lkml/2013/4/1/292
>>
>> Info: sector size = 512
>> Info: total sectors = 11370496 (in 512bytes)
>> Info: zone aligned segment0 blkaddr: 512
>> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
>>
>> mkfs process gets stuck in D state and I see the following in the dmesg:
>>
>> [  257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081
>> [  257.789764]   sector 4194304, nr/cnr 2981888/4294959104
>> [  257.789764]   bio df3840c0, biotail df3848c0, buffer   (null), len
>> 1526726656
>> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
>> [  257.794921] request botched: dev mmcblk0: type=1, flags=122c8081
>> [  257.794921]   sector 4194304, nr/cnr 2981888/4294959104
>> [  257.794921]   bio df3840c0, biotail df3848c0, buffer   (null), len
>> 1526726656
>>
>> This patch fixes this issue.
>>
>> Reported-by: Max Filippov <jcmvbkbc@gmail.com>
>> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
>> Signed-off-by: Vivek Trivedi <t.vivek@samsung.com>
>> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
>> Cc: Shaohua Li <shli@kernel.org>
>> Cc: Kent Overstreet <koverstreet@google.com>
>> Cc: Tejun Heo <tj@kernel.org>
>> Cc: Jens Axboe <axboe@kernel.dk>
>> Cc: <stable@vger.kernel.org>
>> ---
>>  include/linux/blkdev.h |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
>> index 07aa5f6..ff636bd 100644
>> --- a/include/linux/blkdev.h
>> +++ b/include/linux/blkdev.h
>> @@ -844,7 +844,7 @@ static inline unsigned int
>> blk_queue_get_max_sectors(struct request_queue *q,
>>  						     unsigned int cmd_flags)
>>  {
>>  	if (unlikely(cmd_flags & REQ_DISCARD))
>> -		return q->limits.max_discard_sectors;
>> +		return min(q->limits.max_discard_sectors, UINT_MAX >> 9);
>>
>>  	if (unlikely(cmd_flags & REQ_WRITE_SAME))
>>  		return q->limits.max_write_same_sectors;
>
>

[PATCH] block: fix max discard sectors limit

[Namjae Jeon]

From: James Bottomley <JBottomley@Parallels.com>

linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
(block: add plug for blkdev_issue_discard )

For example,
1) DISCARD rq-1 with size size 4GB
2) DISCARD rq-2 with size size 1GB

If these 2 discard requests get merged, final request size will be 5GB.

In this case, request's __data_len field may overflow as it can store
max 4GB(unsigned int).

This issue was observed while doing mkfs.f2fs on 5GB SD card:
https://lkml.org/lkml/2013/4/1/292

Info: sector size = 512
Info: total sectors = 11370496 (in 512bytes)
Info: zone aligned segment0 blkaddr: 512
[  257.789764] blk_update_request: bio idx 0 >= vcnt 0

mkfs process gets stuck in D state and I see the following in the dmesg:

[  257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081
[  257.789764]   sector 4194304, nr/cnr 2981888/4294959104
[  257.789764]   bio df3840c0, biotail df3848c0, buffer   (null), len
1526726656
[  257.789764] blk_update_request: bio idx 0 >= vcnt 0
[  257.794921] request botched: dev mmcblk0: type=1, flags=122c8081
[  257.794921]   sector 4194304, nr/cnr 2981888/4294959104
[  257.794921]   bio df3840c0, biotail df3848c0, buffer   (null), len
1526726656

This patch fixes this issue.

Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Tested-by: Max Filippov <jcmvbkbc@gmail.com>
Cc: <stable@vger.kernel.org>
---
 include/linux/blkdev.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 07aa5f6..ff636bd 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -844,7 +844,7 @@ static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
 						     unsigned int cmd_flags)
 {
 	if (unlikely(cmd_flags & REQ_DISCARD))
-		return q->limits.max_discard_sectors;
+		return min(q->limits.max_discard_sectors, UINT_MAX >> 9);
 
 	if (unlikely(cmd_flags & REQ_WRITE_SAME))
 		return q->limits.max_write_same_sectors;
-- 
1.7.9.5

Re: [PATCH] block: fix max discard sectors limit

[James Bottomley]

On Wed, 2013-04-24 at 22:55 +0900, Namjae Jeon wrote:
> From: James Bottomley <JBottomley@Parallels.com>
> 
> linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
> commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
> (block: add plug for blkdev_issue_discard )
> 
> For example,
> 1) DISCARD rq-1 with size size 4GB
> 2) DISCARD rq-2 with size size 1GB
> 
> If these 2 discard requests get merged, final request size will be 5GB.
> 
> In this case, request's __data_len field may overflow as it can store
> max 4GB(unsigned int).
> 
> This issue was observed while doing mkfs.f2fs on 5GB SD card:
> https://lkml.org/lkml/2013/4/1/292
> 
> Info: sector size = 512
> Info: total sectors = 11370496 (in 512bytes)
> Info: zone aligned segment0 blkaddr: 512
> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> 
> mkfs process gets stuck in D state and I see the following in the dmesg:
> 
> [  257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081
> [  257.789764]   sector 4194304, nr/cnr 2981888/4294959104
> [  257.789764]   bio df3840c0, biotail df3848c0, buffer   (null), len
> 1526726656
> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> [  257.794921] request botched: dev mmcblk0: type=1, flags=122c8081
> [  257.794921]   sector 4194304, nr/cnr 2981888/4294959104
> [  257.794921]   bio df3840c0, biotail df3848c0, buffer   (null), len
> 1526726656
> 
> This patch fixes this issue.
> 
> Reported-by: Max Filippov <jcmvbkbc@gmail.com>
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
> Tested-by: Max Filippov <jcmvbkbc@gmail.com>
> Cc: <stable@vger.kernel.org>

The two signoffs need to be reversed (they follow the chain of
transmission from the author into the kernel), but other than that, this
looks great.  I assume Jens can just hand edit this one issue.

Thanks,

James

Re: [PATCH] block: fix max discard sectors limit

[Jens Axboe]

On Wed, Apr 24 2013, James Bottomley wrote:
> On Wed, 2013-04-24 at 22:55 +0900, Namjae Jeon wrote:
> > From: James Bottomley <JBottomley@Parallels.com>
> > 
> > linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
> > commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
> > (block: add plug for blkdev_issue_discard )
> > 
> > For example,
> > 1) DISCARD rq-1 with size size 4GB
> > 2) DISCARD rq-2 with size size 1GB
> > 
> > If these 2 discard requests get merged, final request size will be 5GB.
> > 
> > In this case, request's __data_len field may overflow as it can store
> > max 4GB(unsigned int).
> > 
> > This issue was observed while doing mkfs.f2fs on 5GB SD card:
> > https://lkml.org/lkml/2013/4/1/292
> > 
> > Info: sector size = 512
> > Info: total sectors = 11370496 (in 512bytes)
> > Info: zone aligned segment0 blkaddr: 512
> > [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> > 
> > mkfs process gets stuck in D state and I see the following in the dmesg:
> > 
> > [  257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081
> > [  257.789764]   sector 4194304, nr/cnr 2981888/4294959104
> > [  257.789764]   bio df3840c0, biotail df3848c0, buffer   (null), len
> > 1526726656
> > [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> > [  257.794921] request botched: dev mmcblk0: type=1, flags=122c8081
> > [  257.794921]   sector 4194304, nr/cnr 2981888/4294959104
> > [  257.794921]   bio df3840c0, biotail df3848c0, buffer   (null), len
> > 1526726656
> > 
> > This patch fixes this issue.
> > 
> > Reported-by: Max Filippov <jcmvbkbc@gmail.com>
> > Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> > Signed-off-by: James Bottomley <JBottomley@Parallels.com>
> > Tested-by: Max Filippov <jcmvbkbc@gmail.com>
> > Cc: <stable@vger.kernel.org>
> 
> The two signoffs need to be reversed (they follow the chain of
> transmission from the author into the kernel), but other than that, this
> looks great.  I assume Jens can just hand edit this one issue.

Yeah, I'll just hand edit thank. Thanks all.

-- 
Jens Axboe

Re: [PATCH] block: fix max discard sectors limit

[Jens Axboe]

On Wed, Apr 24 2013, Namjae Jeon wrote:
> From: James Bottomley <JBottomley@Parallels.com>
> 
> linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
> commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
> (block: add plug for blkdev_issue_discard )
> 
> For example,
> 1) DISCARD rq-1 with size size 4GB
> 2) DISCARD rq-2 with size size 1GB
> 
> If these 2 discard requests get merged, final request size will be 5GB.
> 
> In this case, request's __data_len field may overflow as it can store
> max 4GB(unsigned int).
> 
> This issue was observed while doing mkfs.f2fs on 5GB SD card:
> https://lkml.org/lkml/2013/4/1/292
> 
> Info: sector size = 512
> Info: total sectors = 11370496 (in 512bytes)
> Info: zone aligned segment0 blkaddr: 512
> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> 
> mkfs process gets stuck in D state and I see the following in the dmesg:
> 
> [  257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081
> [  257.789764]   sector 4194304, nr/cnr 2981888/4294959104
> [  257.789764]   bio df3840c0, biotail df3848c0, buffer   (null), len
> 1526726656
> [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> [  257.794921] request botched: dev mmcblk0: type=1, flags=122c8081
> [  257.794921]   sector 4194304, nr/cnr 2981888/4294959104
> [  257.794921]   bio df3840c0, biotail df3848c0, buffer   (null), len
> 1526726656
> 
> This patch fixes this issue.
> 
> Reported-by: Max Filippov <jcmvbkbc@gmail.com>
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
> Tested-by: Max Filippov <jcmvbkbc@gmail.com>
> Cc: <stable@vger.kernel.org>

Thanks! One minor nit - I don't think James signed off on the patch when
he sent it in. James?

-- 
Jens Axboe

Re: [PATCH] block: fix max discard sectors limit

[James Bottomley]

On Wed, 2013-04-24 at 08:23 -0600, Jens Axboe wrote:
> On Wed, Apr 24 2013, Namjae Jeon wrote:
> > From: James Bottomley <JBottomley@Parallels.com>
> > 
> > linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with
> > commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9
> > (block: add plug for blkdev_issue_discard )
> > 
> > For example,
> > 1) DISCARD rq-1 with size size 4GB
> > 2) DISCARD rq-2 with size size 1GB
> > 
> > If these 2 discard requests get merged, final request size will be 5GB.
> > 
> > In this case, request's __data_len field may overflow as it can store
> > max 4GB(unsigned int).
> > 
> > This issue was observed while doing mkfs.f2fs on 5GB SD card:
> > https://lkml.org/lkml/2013/4/1/292
> > 
> > Info: sector size = 512
> > Info: total sectors = 11370496 (in 512bytes)
> > Info: zone aligned segment0 blkaddr: 512
> > [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> > 
> > mkfs process gets stuck in D state and I see the following in the dmesg:
> > 
> > [  257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081
> > [  257.789764]   sector 4194304, nr/cnr 2981888/4294959104
> > [  257.789764]   bio df3840c0, biotail df3848c0, buffer   (null), len
> > 1526726656
> > [  257.789764] blk_update_request: bio idx 0 >= vcnt 0
> > [  257.794921] request botched: dev mmcblk0: type=1, flags=122c8081
> > [  257.794921]   sector 4194304, nr/cnr 2981888/4294959104
> > [  257.794921]   bio df3840c0, biotail df3848c0, buffer   (null), len
> > 1526726656
> > 
> > This patch fixes this issue.
> > 
> > Reported-by: Max Filippov <jcmvbkbc@gmail.com>
> > Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> > Signed-off-by: James Bottomley <JBottomley@Parallels.com>
> > Tested-by: Max Filippov <jcmvbkbc@gmail.com>
> > Cc: <stable@vger.kernel.org>
> 
> Thanks! One minor nit - I don't think James signed off on the patch when
> he sent it in. James?

I didn't, but silence is really acquiescence in this game. However, now
you have my positive confirmation that I'm good with the signoff.

James