From: Jens Axboe <axboe@kernel.dk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
linux-aio <linux-aio@kvack.org>,
linux-block <linux-block@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Christoph Hellwig <hch@lst.de>, Jeff Moyer <jmoyer@redhat.com>,
Avi Kivity <avi@scylladb.com>
Subject: Re: [PATCH 13/16] io_uring: add support for pre-mapped user IO buffers
Date: Wed, 16 Jan 2019 08:32:03 -0700 [thread overview]
Message-ID: <331f63c0-002f-b373-b831-73af9e98f2ef@kernel.dk> (raw)
In-Reply-To: <075af26b-c685-a0db-05e4-fa73f8725b8a@kernel.dk>
On 1/16/19 8:14 AM, Jens Axboe wrote:
> On 1/16/19 3:53 AM, Arnd Bergmann wrote:
>> On Tue, Jan 15, 2019 at 3:56 AM Jens Axboe <axboe@kernel.dk> wrote:
>>
>>> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
>>> index 542757a4c898..e36c264d74e8 100644
>>> --- a/include/linux/syscalls.h
>>> +++ b/include/linux/syscalls.h
>>> @@ -314,6 +314,8 @@ asmlinkage long sys_io_uring_setup(u32 entries,
>>> struct io_uring_params __user *p);
>>> asmlinkage long sys_io_uring_enter(unsigned int fd, u32 to_submit,
>>> u32 min_complete, u32 flags);
>>> +asmlinkage long sys_io_uring_register(unsigned int fd, unsigned op,
>>> + void __user *arg);
>>>
>>
>> Would it be possible to make this a typed pointer instead? If this needs to
>> be extended later to pass a different structure, a new system call may
>> be better for consistency than overloading the argument in various
>> ways.
>
> As you can see from the later patch for registering files, it'll be used
> for other structs too. Feels a little silly to add an extra system call
> for that. I agree the void * isn't the prettiest thing in the world, but
> at least it allows us to extend the API without having to add even more
> system calls down the line.
With the __u64 changes, we end up with this:
struct io_uring_register_buffers {
__u64 iovecs; /* pointer to iovecs array */
__u32 nr_iovecs; /* number of iovecs in array */
__u32 pad;
};
struct io_uring_register_files {
__u64 fds;
__u32 nr_fds;
__u32 pad;
};
which are identical. So the question then becomes if I should just make
these opaque enough to be the same thing, ala:
struct io_uring_register_data {
__u64 data;
__u32 nr_elems;
__u32 pad;
};
and then probably add a bit more reserved space so we have something
that can be extended...
--
Jens Axboe
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WARNING: multiple messages have this Message-ID (diff)
From: Jens Axboe <axboe@kernel.dk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
linux-aio <linux-aio@kvack.org>,
linux-block <linux-block@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Christoph Hellwig <hch@lst.de>, Jeff Moyer <jmoyer@redhat.com>,
Avi Kivity <avi@scylladb.com>
Subject: Re: [PATCH 13/16] io_uring: add support for pre-mapped user IO buffers
Date: Wed, 16 Jan 2019 08:32:03 -0700 [thread overview]
Message-ID: <331f63c0-002f-b373-b831-73af9e98f2ef@kernel.dk> (raw)
Message-ID: <20190116153203.trONsawxgk81lMqULxgO5mIVafAtlrfMwUniKmYE1nE@z> (raw)
In-Reply-To: <075af26b-c685-a0db-05e4-fa73f8725b8a@kernel.dk>
On 1/16/19 8:14 AM, Jens Axboe wrote:
> On 1/16/19 3:53 AM, Arnd Bergmann wrote:
>> On Tue, Jan 15, 2019 at 3:56 AM Jens Axboe <axboe@kernel.dk> wrote:
>>
>>> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
>>> index 542757a4c898..e36c264d74e8 100644
>>> --- a/include/linux/syscalls.h
>>> +++ b/include/linux/syscalls.h
>>> @@ -314,6 +314,8 @@ asmlinkage long sys_io_uring_setup(u32 entries,
>>> struct io_uring_params __user *p);
>>> asmlinkage long sys_io_uring_enter(unsigned int fd, u32 to_submit,
>>> u32 min_complete, u32 flags);
>>> +asmlinkage long sys_io_uring_register(unsigned int fd, unsigned op,
>>> + void __user *arg);
>>>
>>
>> Would it be possible to make this a typed pointer instead? If this needs to
>> be extended later to pass a different structure, a new system call may
>> be better for consistency than overloading the argument in various
>> ways.
>
> As you can see from the later patch for registering files, it'll be used
> for other structs too. Feels a little silly to add an extra system call
> for that. I agree the void * isn't the prettiest thing in the world, but
> at least it allows us to extend the API without having to add even more
> system calls down the line.
With the __u64 changes, we end up with this:
struct io_uring_register_buffers {
__u64 iovecs; /* pointer to iovecs array */
__u32 nr_iovecs; /* number of iovecs in array */
__u32 pad;
};
struct io_uring_register_files {
__u64 fds;
__u32 nr_fds;
__u32 pad;
};
which are identical. So the question then becomes if I should just make
these opaque enough to be the same thing, ala:
struct io_uring_register_data {
__u64 data;
__u32 nr_elems;
__u32 pad;
};
and then probably add a bit more reserved space so we have something
that can be extended...
--
Jens Axboe
next prev parent reply other threads:[~2019-01-16 15:32 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-15 2:55 (unknown), Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 01/16] fs: add an iopoll method to struct file_operations Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 02/16] block: wire up block device iopoll method Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 03/16] block: add bio_set_polled() helper Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 04/16] iomap: wire up the iopoll method Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 05/16] Add io_uring IO interface Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 16:51 ` Jonathan Corbet
2019-01-15 16:51 ` Jonathan Corbet
2019-01-15 16:55 ` Jens Axboe
2019-01-15 16:55 ` Jens Axboe
2019-01-15 17:26 ` Jens Axboe
2019-01-15 17:26 ` Jens Axboe
2019-01-16 10:41 ` Arnd Bergmann
2019-01-16 10:41 ` Arnd Bergmann
2019-01-16 11:00 ` Arnd Bergmann
2019-01-16 11:00 ` Arnd Bergmann
2019-01-16 15:12 ` Jens Axboe
2019-01-16 15:12 ` Jens Axboe
2019-01-16 15:16 ` Arnd Bergmann
2019-01-16 15:16 ` Arnd Bergmann
2019-01-16 15:25 ` Jens Axboe
2019-01-16 15:25 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 06/16] io_uring: add fsync support Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 07/16] io_uring: support for IO polling Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 08/16] io_uring: add submission side request cache Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 09/16] fs: add fget_many() and fput_many() Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 10/16] io_uring: use fget/fput_many() for file references Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 11/16] io_uring: batch io_kiocb allocation Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 12/16] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 13/16] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-16 10:53 ` Arnd Bergmann
2019-01-16 15:14 ` Jens Axboe
2019-01-16 15:14 ` Jens Axboe
2019-01-16 15:32 ` Jens Axboe [this message]
2019-01-16 15:32 ` Jens Axboe
2019-01-16 15:41 ` Arnd Bergmann
2019-01-16 15:47 ` Jens Axboe
2019-01-16 15:47 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 14/16] io_uring: add submission polling Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 15/16] io_uring: add file registration Jens Axboe
2019-01-15 2:55 ` Jens Axboe
2019-01-16 10:45 ` Arnd Bergmann
2019-01-16 10:45 ` Arnd Bergmann
2019-01-16 15:15 ` Jens Axboe
2019-01-16 15:15 ` Jens Axboe
2019-01-15 2:55 ` [PATCH 16/16] io_uring: add io_uring_event cache hit information Jens Axboe
2019-01-15 2:55 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2019-01-12 21:29 [PATCHSET v3] io_uring IO interface Jens Axboe
2019-01-12 21:30 ` [PATCH 13/16] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-01-12 21:30 ` Jens Axboe
2019-01-08 16:56 [PATCHSET v1] io_uring IO interface Jens Axboe
2019-01-08 16:56 ` [PATCH 13/16] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-01-08 16:56 ` Jens Axboe
2019-01-09 12:16 ` Christoph Hellwig
2019-01-09 17:06 ` Jens Axboe
2019-01-09 17:06 ` Jens Axboe
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