From: Logan Gunthorpe <logang@deltatee.com>
To: Sagi Grimberg <sagi@grimberg.me>, Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jens Axboe <axboe@fb.com>,
Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
Stephen Bates <sbates@raithlin.com>,
linux-block@vger.kernel.org, Keith Busch <kbusch@kernel.org>,
linux-fsdevel@vger.kernel.org, Max Gurtovoy <maxg@mellanox.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v6 02/16] chardev: introduce cdev_get_by_path()
Date: Fri, 26 Jul 2019 09:46:40 -0600 [thread overview]
Message-ID: <fce9d627-3bf7-2c63-dbdc-5b252792cc36@deltatee.com> (raw)
In-Reply-To: <7f48a40c-6e0f-2545-a939-45fc10862dfd@grimberg.me>
On 2019-07-25 10:29 p.m., Sagi Grimberg wrote:
>
>>>>>>>> NVMe-OF is configured using configfs. The target is specified by
>>>>>>>> the
>>>>>>>> user writing a path to a configfs attribute. This is the way it
>>>>>>>> works
>>>>>>>> today but with blkdev_get_by_path()[1]. For the passthru code,
>>>>>>>> we need
>>>>>>>> to get a nvme_ctrl instead of a block_device, but the principal
>>>>>>>> is the same.
>>>>>>>
>>>>>>> Why isn't a fd being passed in there instead of a random string?
>>>>>>
>>>>>> I suppose we could echo a string of the file descriptor number there,
>>>>>> and look up the fd in the process' file descriptor table ...
>>>>>
>>>>> Assuming that there is a open handle somewhere out there...
>>>
>>> Yes, that would be a step backwards from an interface. The user would
>>> then need a special process to open the fd and pass it through configfs.
>>> They couldn't just do it with basic bash commands.
>>
>> First of all, they can, but... WTF not have filp_open() done right there?
>> Yes, by name. With permission checks done. And pick your object from
>> the
>> sodding struct file you'll get.
>>
>> What's the problem? Why do you need cdev lookups, etc., when you are
>> dealing with files under your full control? Just open them and use
>> ->private_data or whatever you set in ->open() to access the damn thing.
>> All there is to it...
> Oh this is so much simpler. There is really no point in using anything
> else. Just need to remember to compare f->f_op to what we expect to make
> sure that it is indeed the same device class.
Yes, that sounds like a good idea. I'll do this for v2.
Thanks,
Logan
next prev parent reply other threads:[~2019-07-26 15:46 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 17:23 [PATCH v6 00/16] nvmet: add target passthru commands support Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 01/16] chardev: factor out cdev_lookup() helper Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 02/16] chardev: introduce cdev_get_by_path() Logan Gunthorpe
2019-07-25 17:40 ` Greg Kroah-Hartman
2019-07-25 17:53 ` Logan Gunthorpe
2019-07-25 17:58 ` Matthew Wilcox
2019-07-25 18:08 ` Logan Gunthorpe
2019-07-25 18:08 ` Greg Kroah-Hartman
2019-07-25 18:14 ` Logan Gunthorpe
2019-07-25 18:27 ` Greg Kroah-Hartman
2019-07-25 18:36 ` Logan Gunthorpe
2019-07-25 19:02 ` Sagi Grimberg
2019-07-25 19:34 ` Greg Kroah-Hartman
2019-07-25 19:37 ` Sagi Grimberg
2019-07-25 19:43 ` Greg Kroah-Hartman
2019-07-25 19:45 ` Sagi Grimberg
2019-07-25 19:43 ` Sagi Grimberg
2019-07-25 19:41 ` Logan Gunthorpe
2019-07-25 19:00 ` Matthew Wilcox
2019-07-25 19:05 ` Sagi Grimberg
2019-07-25 19:11 ` Matthew Wilcox
2019-07-25 19:24 ` Logan Gunthorpe
2019-07-25 19:26 ` Matthew Wilcox
2019-07-25 19:31 ` Logan Gunthorpe
2019-07-25 23:55 ` Al Viro
2019-07-26 4:29 ` Sagi Grimberg
2019-07-26 7:13 ` Greg Kroah-Hartman
2019-07-26 15:46 ` Logan Gunthorpe [this message]
2019-07-25 19:31 ` Sagi Grimberg
2019-07-25 18:10 ` Greg Kroah-Hartman
2019-07-25 18:16 ` Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 03/16] chardev: export cdev_put() Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 04/16] nvme-core: introduce nvme_get_by_path() Logan Gunthorpe
2019-07-25 17:50 ` Matthew Wilcox
2019-07-25 17:54 ` Logan Gunthorpe
2019-07-25 19:58 ` Keith Busch
2019-07-25 20:12 ` Sagi Grimberg
2019-07-25 20:28 ` Logan Gunthorpe
2019-07-25 20:31 ` Keith Busch
2019-07-25 20:37 ` Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 05/16] nvme-core: export existing ctrl and ns interfaces Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 06/16] nvmet: add return value to nvmet_add_async_event() Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 07/16] nvmet: make nvmet_copy_ns_identifier() non-static Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 08/16] nvmet-passthru: update KConfig with config passthru option Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 09/16] nvmet-passthru: add passthru code to process commands Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 10/16] nvmet-passthru: add enable/disable helpers Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 11/16] nvmet-core: allow one host per passthru-ctrl Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 12/16] nvmet-core: don't check the data len for pt-ctrl Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 13/16] nvmet-configfs: introduce passthru configfs interface Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 14/16] block: don't check blk_rq_is_passthrough() in blk_do_io_stat() Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 15/16] block: call blk_account_io_start() in blk_execute_rq_nowait() Logan Gunthorpe
2019-07-25 17:23 ` [PATCH v6 16/16] nvmet-passthru: support block accounting Logan Gunthorpe
2019-07-26 6:23 ` [PATCH v6 00/16] nvmet: add target passthru commands support Hannes Reinecke
2019-07-26 17:07 ` Logan Gunthorpe
2019-07-26 22:21 ` Sagi Grimberg
2019-07-26 22:37 ` Logan Gunthorpe
2019-07-26 23:13 ` Sagi Grimberg
2019-07-27 0:09 ` Logan Gunthorpe
2019-07-27 0:50 ` Stephen Bates
2019-07-29 16:15 ` Sagi Grimberg
2019-07-29 16:17 ` Logan Gunthorpe
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