Add a helper blk_mq_alloc_request_nocache() to alloc request without
cache. This makes blk_mq_alloc_request() more readable.
Signed-off-by: Jinlong Chen <[email protected]>
---
block/blk-mq.c | 47 +++++++++++++++++++++++++++++------------------
1 file changed, 29 insertions(+), 18 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 87a6348a0d0a..2fae111a42c8 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -572,36 +572,47 @@ static struct request *blk_mq_alloc_cached_request(struct request_queue *q,
return rq;
}
-struct request *blk_mq_alloc_request(struct request_queue *q, blk_opf_t opf,
- blk_mq_req_flags_t flags)
+static struct request *blk_mq_alloc_request_nocache(struct request_queue *q,
+ blk_opf_t opf, blk_mq_req_flags_t flags)
{
- struct request *rq;
-
- rq = blk_mq_alloc_cached_request(q, opf, flags);
- if (!rq) {
- struct blk_mq_alloc_data data = {
+ struct blk_mq_alloc_data data = {
.q = q,
.flags = flags,
.cmd_flags = opf,
.nr_tags = 1,
};
- int ret;
+ struct request *rq;
+ int ret;
- ret = blk_queue_enter(q, flags);
- if (ret)
- return ERR_PTR(ret);
+ ret = blk_queue_enter(q, flags);
+ if (ret)
+ return ERR_PTR(ret);
- rq = __blk_mq_alloc_requests(&data);
- if (!rq)
- goto out_queue_exit;
+ rq = __blk_mq_alloc_requests(&data);
+ if (!rq) {
+ rq = ERR_PTR(-EWOULDBLOCK);
+ blk_queue_exit(q);
}
+
+ return rq;
+}
+
+struct request *blk_mq_alloc_request(struct request_queue *q, blk_opf_t opf,
+ blk_mq_req_flags_t flags)
+{
+ struct request *rq;
+
+ rq = blk_mq_alloc_cached_request(q, opf, flags);
+ if (!rq) {
+ rq = blk_mq_alloc_request_nocache(q, opf, flags);
+ if (IS_ERR(rq))
+ return rq;
+ }
+
rq->__data_len = 0;
rq->__sector = (sector_t) -1;
rq->bio = rq->biotail = NULL;
- return rq;
-out_queue_exit:
- blk_queue_exit(q);
- return ERR_PTR(-EWOULDBLOCK);
+ return rq;
}
EXPORT_SYMBOL(blk_mq_alloc_request);
--
2.31.1
On Tue, Nov 01, 2022 at 11:11:37PM +0800, Jinlong Chen wrote:
> Add a helper blk_mq_alloc_request_nocache() to alloc request without
> cache. This makes blk_mq_alloc_request() more readable.
>
> Signed-off-by: Jinlong Chen <[email protected]>
> ---
> block/blk-mq.c | 47 +++++++++++++++++++++++++++++------------------
> 1 file changed, 29 insertions(+), 18 deletions(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 87a6348a0d0a..2fae111a42c8 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -572,36 +572,47 @@ static struct request *blk_mq_alloc_cached_request(struct request_queue *q,
> return rq;
> }
>
> +static struct request *blk_mq_alloc_request_nocache(struct request_queue *q,
> + blk_opf_t opf, blk_mq_req_flags_t flags)
The name is a bit odd, but I can't think off a better one.
> + struct blk_mq_alloc_data data = {
> .q = q,
> .flags = flags,
> .cmd_flags = opf,
> .nr_tags = 1,
> };
And this now has superflous indenation. Overall, while the separate
helper looks marginally nicer, I'm not really sure it is worth the
churn.
>> +static struct request *blk_mq_alloc_request_nocache(struct request_queue *q,
>> + blk_opf_t opf, blk_mq_req_flags_t flags)
>
> The name is a bit odd, but I can't think off a better one.
>
>> + struct blk_mq_alloc_data data = {
>> .q = q,
>> .flags = flags,
>> .cmd_flags = opf,
>> .nr_tags = 1,
>> };
>
> And this now has superflous indenation. Overall, while the separate
> helper looks marginally nicer, I'm not really sure it is worth the
> churn.
existing code is fine here than adding this indentation which
is not worth a churn...
-ck
> On Tue, Nov 01, 2022 at 11:11:37PM +0800, Jinlong Chen wrote:
> > Add a helper blk_mq_alloc_request_nocache() to alloc request without
> > cache. This makes blk_mq_alloc_request() more readable.
> >
> > Signed-off-by: Jinlong Chen <[email protected]>
> > ---
> > block/blk-mq.c | 47 +++++++++++++++++++++++++++++------------------
> > 1 file changed, 29 insertions(+), 18 deletions(-)
> >
> > diff --git a/block/blk-mq.c b/block/blk-mq.c
> > index 87a6348a0d0a..2fae111a42c8 100644
> > --- a/block/blk-mq.c
> > +++ b/block/blk-mq.c
> > @@ -572,36 +572,47 @@ static struct request *blk_mq_alloc_cached_request(struct request_queue *q,
> > return rq;
> > }
> >
> > +static struct request *blk_mq_alloc_request_nocache(struct request_queue *q,
> > + blk_opf_t opf, blk_mq_req_flags_t flags)
>
> The name is a bit odd, but I can't think off a better one.
>
> > + struct blk_mq_alloc_data data = {
> > .q = q,
> > .flags = flags,
> > .cmd_flags = opf,
> > .nr_tags = 1,
> > };
>
> And this now has superflous indenation. Overall, while the separate
> helper looks marginally nicer, I'm not really sure it is worth the
> churn.
I'll drop the patch if you think it is not worth the churn. But I
started doing this because of the following goto statement:
rq = blk_mq_alloc_cached_request(q, opf, flags);
if (!rq) {
[...]
ret = blk_queue_enter(q, flags);
[...]
rq = __blk_mq_alloc_requests(&data);
if (!rq)
goto out_queue_exit;
}
[...]
out_queue_exit:
blk_queue_exit(q);
return ERR_PTR(-EWOULDBLOCK);
Queue entering has been moved into the fallback path, left queue exiting
outside. Should I just eliminate the goto statement and move the error
handling into the fallback path too? Like:
rq = blk_mq_alloc_cached_request(q, opf, flags);
if (!rq) {
[...]
ret = blk_queue_enter(q, flags);
[...]
rq = __blk_mq_alloc_requests(&data);
if (!rq) {
blk_queue_exit(q);
return ERR_PTR(-EWOULDBLOCK);
}
}
Thanks!
Jinlong Chen
On 11/1/22 8:19 PM, Jinlong Chen wrote:
>> On Tue, Nov 01, 2022 at 11:11:37PM +0800, Jinlong Chen wrote:
>>> Add a helper blk_mq_alloc_request_nocache() to alloc request without
>>> cache. This makes blk_mq_alloc_request() more readable.
>>>
>>> Signed-off-by: Jinlong Chen <[email protected]>
>>> ---
>>> block/blk-mq.c | 47 +++++++++++++++++++++++++++++------------------
>>> 1 file changed, 29 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/block/blk-mq.c b/block/blk-mq.c
>>> index 87a6348a0d0a..2fae111a42c8 100644
>>> --- a/block/blk-mq.c
>>> +++ b/block/blk-mq.c
>>> @@ -572,36 +572,47 @@ static struct request *blk_mq_alloc_cached_request(struct request_queue *q,
>>> return rq;
>>> }
>>>
>>> +static struct request *blk_mq_alloc_request_nocache(struct request_queue *q,
>>> + blk_opf_t opf, blk_mq_req_flags_t flags)
>>
>> The name is a bit odd, but I can't think off a better one.
>>
>>> + struct blk_mq_alloc_data data = {
>>> .q = q,
>>> .flags = flags,
>>> .cmd_flags = opf,
>>> .nr_tags = 1,
>>> };
>>
>> And this now has superflous indenation. Overall, while the separate
>> helper looks marginally nicer, I'm not really sure it is worth the
>> churn.
>
> I'll drop the patch if you think it is not worth the churn. But I
> started doing this because of the following goto statement:
Please just drop it, I don't think it's an improvement.
--
Jens Axboe
> -----原始邮件-----
> 发件人: "Jens Axboe" <[email protected]>
> 发送时间: 2022-11-02 10:25:27 (星期三)
> 收件人: "Jinlong Chen" <[email protected]>, "Christoph Hellwig" <[email protected]>
> 抄送: [email protected], [email protected]
> 主题: Re: [PATCH 4/4] blk-mq: improve readability of blk_mq_alloc_request()
>
> On 11/1/22 8:19 PM, Jinlong Chen wrote:
> >> On Tue, Nov 01, 2022 at 11:11:37PM +0800, Jinlong Chen wrote:
> >>> Add a helper blk_mq_alloc_request_nocache() to alloc request without
> >>> cache. This makes blk_mq_alloc_request() more readable.
> >>>
> >>> Signed-off-by: Jinlong Chen <[email protected]>
> >>> ---
> >>> block/blk-mq.c | 47 +++++++++++++++++++++++++++++------------------
> >>> 1 file changed, 29 insertions(+), 18 deletions(-)
> >>>
> >>> diff --git a/block/blk-mq.c b/block/blk-mq.c
> >>> index 87a6348a0d0a..2fae111a42c8 100644
> >>> --- a/block/blk-mq.c
> >>> +++ b/block/blk-mq.c
> >>> @@ -572,36 +572,47 @@ static struct request *blk_mq_alloc_cached_request(struct request_queue *q,
> >>> return rq;
> >>> }
> >>>
> >>> +static struct request *blk_mq_alloc_request_nocache(struct request_queue *q,
> >>> + blk_opf_t opf, blk_mq_req_flags_t flags)
> >>
> >> The name is a bit odd, but I can't think off a better one.
> >>
> >>> + struct blk_mq_alloc_data data = {
> >>> .q = q,
> >>> .flags = flags,
> >>> .cmd_flags = opf,
> >>> .nr_tags = 1,
> >>> };
> >>
> >> And this now has superflous indenation. Overall, while the separate
> >> helper looks marginally nicer, I'm not really sure it is worth the
> >> churn.
> >
> > I'll drop the patch if you think it is not worth the churn. But I
> > started doing this because of the following goto statement:
>
> Please just drop it, I don't think it's an improvement.
Ok, then I'll just resend patch 2 without the silly goto return NULL and
patch 3.
Thanks!
Jinlong Chen