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From: Jinpu Wang <jinpu.wang@cloud.ionos.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Jack Wang <jinpuwang@gmail.com>,
	linux-block@vger.kernel.org, linux-rdma@vger.kernel.org,
	Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@infradead.org>,
	Sagi Grimberg <sagi@grimberg.me>,
	Jason Gunthorpe <jgg@mellanox.com>,
	Doug Ledford <dledford@redhat.com>,
	Danil Kipnis <danil.kipnis@cloud.ionos.com>,
	rpenyaev@suse.de
Subject: Re: [PATCH v4 21/25] ibnbd: server: functionality for IO submission to file or block dev
Date: Thu, 26 Sep 2019 16:04:03 +0200
Message-ID: <CAMGffE=RpTjDX-LL2E5t_eOF8iwG=UpgWFcnB3tz-N-PQ0etoQ@mail.gmail.com> (raw)
In-Reply-To: <d1208649-5c25-578f-967e-f7a3c9edd9ce@acm.org>

Sorry for the slow reply.

On Wed, Sep 18, 2019 at 11:46 PM Bart Van Assche <bvanassche@acm.org> wrote:
>
> On 6/20/19 8:03 AM, Jack Wang wrote:
> > +#undef pr_fmt
> > +#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
>
> Same comment as for a previous patch: please do not include line number
> information in pr_fmt().
Ok, will be removed.

>
> > +static int ibnbd_dev_vfs_open(struct ibnbd_dev *dev, const char *path,
> > +                           fmode_t flags)
> > +{
> > +     int oflags = O_DSYNC; /* enable write-through */
> > +
> > +     if (flags & FMODE_WRITE)
> > +             oflags |= O_RDWR;
> > +     else if (flags & FMODE_READ)
> > +             oflags |= O_RDONLY;
> > +     else
> > +             return -EINVAL;
> > +
> > +     dev->file = filp_open(path, oflags, 0);
> > +     return PTR_ERR_OR_ZERO(dev->file);
> > +}
>
> Isn't the use of O_DSYNC something that should be configurable?
I know scst allow O_DSYNC to be configured, but in our production, we
only use with O_DSYNC,
 we sure can add options to allow it to configure it, but we don't
have a need yet.
>
> > +struct ibnbd_dev *ibnbd_dev_open(const char *path, fmode_t flags,
> > +                              enum ibnbd_io_mode mode, struct bio_set *bs,
> > +                              ibnbd_dev_io_fn io_cb)
> > +{
> > +     struct ibnbd_dev *dev;
> > +     int ret;
> > +
> > +     dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> > +     if (!dev)
> > +             return ERR_PTR(-ENOMEM);
> > +
> > +     if (mode == IBNBD_BLOCKIO) {
> > +             dev->blk_open_flags = flags;
> > +             ret = ibnbd_dev_blk_open(dev, path, dev->blk_open_flags);
> > +             if (ret)
> > +                     goto err;
> > +     } else if (mode == IBNBD_FILEIO) {
> > +             dev->blk_open_flags = FMODE_READ;
> > +             ret = ibnbd_dev_blk_open(dev, path, dev->blk_open_flags);
> > +             if (ret)
> > +                     goto err;
> > +
> > +             ret = ibnbd_dev_vfs_open(dev, path, flags);
> > +             if (ret)
> > +                     goto blk_put;
>
> This looks really weird. Why to call ibnbd_dev_blk_open() first for file
> I/O mode? Why to set dev->blk_open_flags to FMODE_READ in file I/O mode?

The reason behind is we want to be able to symlink to the block device.
And for File io mode, we only allow exporting block device.


>
> > +static int ibnbd_dev_blk_submit_io(struct ibnbd_dev *dev, sector_t sector,
> > +                                void *data, size_t len, u32 bi_size,
> > +                                enum ibnbd_io_flags flags, short prio,
> > +                                void *priv)
> > +{
> > +     struct request_queue *q = bdev_get_queue(dev->bdev);
> > +     struct ibnbd_dev_blk_io *io;
> > +     struct bio *bio;
> > +
> > +     /* check if the buffer is suitable for bdev */
> > +     if (unlikely(WARN_ON(!blk_rq_aligned(q, (unsigned long)data, len))))
> > +             return -EINVAL;
> > +
> > +     /* Generate bio with pages pointing to the rdma buffer */
> > +     bio = ibnbd_bio_map_kern(q, data, dev->ibd_bio_set, len, GFP_KERNEL);
> > +     if (unlikely(IS_ERR(bio)))
> > +             return PTR_ERR(bio);
> > +
> > +     io = kmalloc(sizeof(*io), GFP_KERNEL);
> > +     if (unlikely(!io)) {
> > +             bio_put(bio);
> > +             return -ENOMEM;
> > +     }
> > +
> > +     io->dev         = dev;
> > +     io->priv        = priv;
> > +
> > +     bio->bi_end_io          = ibnbd_dev_bi_end_io;
> > +     bio->bi_private         = io;
> > +     bio->bi_opf             = ibnbd_to_bio_flags(flags);
> > +     bio->bi_iter.bi_sector  = sector;
> > +     bio->bi_iter.bi_size    = bi_size;
> > +     bio_set_prio(bio, prio);
> > +     bio_set_dev(bio, dev->bdev);
> > +
> > +     submit_bio(bio);
> > +
> > +     return 0;
> > +}
>
> Can struct bio and struct ibnbd_dev_blk_io be combined into a single
> data structure by passing the size of the latter data structure as the
> front_pad argument to bioset_init()?
Thanks for the suggestion, will look into it,
looks we can embed struct bio to struct ibnbd_dev_blk_io.
>
> > +static void ibnbd_dev_file_submit_io_worker(struct work_struct *w)
> > +{
> > +     struct ibnbd_dev_file_io_work *dev_work;
> > +     struct file *f;
> > +     int ret, len;
> > +     loff_t off;
> > +
> > +     dev_work = container_of(w, struct ibnbd_dev_file_io_work, work);
> > +     off = dev_work->sector * ibnbd_dev_get_logical_bsize(dev_work->dev);
> > +     f = dev_work->dev->file;
> > +     len = dev_work->bi_size;
> > +
> > +     if (ibnbd_op(dev_work->flags) == IBNBD_OP_FLUSH) {
> > +             ret = ibnbd_dev_file_handle_flush(dev_work, off);
> > +             if (unlikely(ret))
> > +                     goto out;
> > +     }
> > +
> > +     if (ibnbd_op(dev_work->flags) == IBNBD_OP_WRITE_SAME) {
> > +             ret = ibnbd_dev_file_handle_write_same(dev_work);
> > +             if (unlikely(ret))
> > +                     goto out;
> > +     }
> > +
> > +     /* TODO Implement support for DIRECT */
> > +     if (dev_work->bi_size) {
> > +             loff_t off_tmp = off;
> > +
> > +             if (ibnbd_op(dev_work->flags) == IBNBD_OP_WRITE)
> > +                     ret = kernel_write(f, dev_work->data, dev_work->bi_size,
> > +                                        &off_tmp);
> > +             else
> > +                     ret = kernel_read(f, dev_work->data, dev_work->bi_size,
> > +                                       &off_tmp);
> > +
> > +             if (unlikely(ret < 0)) {
> > +                     goto out;
> > +             } else if (unlikely(ret != dev_work->bi_size)) {
> > +                     /* TODO implement support for partial completions */
> > +                     ret = -EIO;
> > +                     goto out;
> > +             } else {
> > +                     ret = 0;
> > +             }
> > +     }
> > +
> > +     if (dev_work->flags & IBNBD_F_FUA)
> > +             ret = ibnbd_dev_file_handle_fua(dev_work, off);
> > +out:
> > +     dev_work->dev->io_cb(dev_work->priv, ret);
> > +     kfree(dev_work);
> > +}
> > +
> > +static int ibnbd_dev_file_submit_io(struct ibnbd_dev *dev, sector_t sector,
> > +                                 void *data, size_t len, size_t bi_size,
> > +                                 enum ibnbd_io_flags flags, void *priv)
> > +{
> > +     struct ibnbd_dev_file_io_work *w;
> > +
> > +     if (!ibnbd_flags_supported(flags)) {
> > +             pr_info_ratelimited("Unsupported I/O flags: 0x%x on device "
> > +                                 "%s\n", flags, dev->name);
> > +             return -ENOTSUPP;
> > +     }
> > +
> > +     w = kmalloc(sizeof(*w), GFP_KERNEL);
> > +     if (!w)
> > +             return -ENOMEM;
> > +
> > +     w->dev          = dev;
> > +     w->priv         = priv;
> > +     w->sector       = sector;
> > +     w->data         = data;
> > +     w->len          = len;
> > +     w->bi_size      = bi_size;
> > +     w->flags        = flags;
> > +     INIT_WORK(&w->work, ibnbd_dev_file_submit_io_worker);
> > +
> > +     if (unlikely(!queue_work(fileio_wq, &w->work))) {
> > +             kfree(w);
> > +             return -EEXIST;
> > +     }
> > +
> > +     return 0;
> > +}
>
> Please use the in-kernel asynchronous I/O API instead of kernel_read()
> and kernel_write() and remove the fileio_wq workqueue. Examples of how
> to use call_read_iter() and call_write_iter() are available in the loop
> driver and also in drivers/target/target_core_file.c.
What the benefits of using call_read_iter/call_write_iter, does it
offer better performance?

>
> > +/** ibnbd_dev_init() - Initialize ibnbd_dev
> > + *
> > + * This functions initialized the ibnbd-dev component.
> > + * It has to be called 1x time before ibnbd_dev_open() is used
> > + */
> > +int ibnbd_dev_init(void);
>
> It is great so see kernel-doc headers above functions but I'm not sure
> these should be in .h files. I think most kernel developers prefer to
> see kernel-doc headers for functions in .c files because that makes it
> more likely that the implementation and the documentation stay in sync.
>
Ok, will move the kernel doc to source code.
I feel for exported functions, it's more common to do it in header files.
For this case, I think it's fine to move the kernel-doc to the c file.

Thanks,
Jinpu

  reply index

Thread overview: 123+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190620150337.7847-1-jinpuwang@gmail.com>
2019-06-20 15:03 ` [PATCH v4 01/25] sysfs: export sysfs_remove_file_self() Jack Wang
2019-09-23 17:21   ` Bart Van Assche
2019-09-25  9:30     ` Danil Kipnis
2019-07-09  9:55 ` [PATCH v4 00/25] InfiniBand Transport (IBTRS) and Network Block Device (IBNBD) Danil Kipnis
2019-07-09 11:00   ` Leon Romanovsky
2019-07-09 11:17     ` Greg KH
2019-07-09 11:57       ` Jinpu Wang
2019-07-09 13:32       ` Leon Romanovsky
2019-07-09 15:39       ` Bart Van Assche
2019-07-09 11:37     ` Jinpu Wang
2019-07-09 12:06       ` Jason Gunthorpe
2019-07-09 13:15         ` Jinpu Wang
2019-07-09 13:19           ` Jason Gunthorpe
2019-07-09 14:17             ` Jinpu Wang
2019-07-09 21:27             ` Sagi Grimberg
2019-07-19 13:12               ` Danil Kipnis
2019-07-10 14:55     ` Danil Kipnis
2019-07-09 12:04   ` Jason Gunthorpe
2019-07-09 19:45   ` Sagi Grimberg
2019-07-10 13:55     ` Jason Gunthorpe
2019-07-10 16:25       ` Sagi Grimberg
2019-07-10 17:25         ` Jason Gunthorpe
2019-07-10 19:11           ` Sagi Grimberg
2019-07-11  7:27             ` Danil Kipnis
2019-07-11  8:54     ` Danil Kipnis
2019-07-12  0:22       ` Sagi Grimberg
2019-07-12  7:57         ` Jinpu Wang
2019-07-12 19:40           ` Sagi Grimberg
2019-07-15 11:21             ` Jinpu Wang
2019-07-12 10:58         ` Danil Kipnis
     [not found] ` <20190620150337.7847-26-jinpuwang@gmail.com>
2019-07-09 15:10   ` [PATCH v4 25/25] MAINTAINERS: Add maintainer for IBNBD/IBTRS modules Leon Romanovsky
2019-07-09 15:18     ` Jinpu Wang
2019-07-09 15:51       ` Leon Romanovsky
2019-09-13 23:56   ` Bart Van Assche
2019-09-19 10:30     ` Jinpu Wang
     [not found] ` <20190620150337.7847-16-jinpuwang@gmail.com>
2019-09-13 22:10   ` [PATCH v4 15/25] ibnbd: private headers with IBNBD protocol structs and helpers Bart Van Assche
2019-09-15 14:30     ` Jinpu Wang
2019-09-16  5:27       ` Leon Romanovsky
2019-09-16 13:45         ` Bart Van Assche
2019-09-17 15:41           ` Leon Romanovsky
2019-09-17 15:52             ` Jinpu Wang
2019-09-16  7:08       ` Danil Kipnis
2019-09-16 14:57       ` Jinpu Wang
2019-09-16 17:25         ` Bart Van Assche
2019-09-17 12:27           ` Jinpu Wang
2019-09-16 15:39       ` Jinpu Wang
2019-09-18 15:26         ` Bart Van Assche
2019-09-18 16:11           ` Jinpu Wang
     [not found] ` <20190620150337.7847-17-jinpuwang@gmail.com>
2019-09-13 22:25   ` [PATCH v4 16/25] ibnbd: client: private header with client structs and functions Bart Van Assche
2019-09-17 16:36     ` Jinpu Wang
2019-09-25 23:43       ` Danil Kipnis
2019-09-26 10:00         ` Jinpu Wang
     [not found] ` <20190620150337.7847-18-jinpuwang@gmail.com>
2019-09-13 23:46   ` [PATCH v4 17/25] ibnbd: client: main functionality Bart Van Assche
2019-09-16 14:17     ` Danil Kipnis
2019-09-16 16:46       ` Bart Van Assche
2019-09-17 11:39         ` Danil Kipnis
2019-09-18  7:14           ` Danil Kipnis
2019-09-18 15:47             ` Bart Van Assche
2019-09-20  8:29               ` Danil Kipnis
2019-09-25 22:26               ` Danil Kipnis
2019-09-26  9:55                 ` Roman Penyaev
2019-09-26 15:01                   ` Bart Van Assche
2019-09-27  8:52                     ` Roman Penyaev
2019-09-27  9:32                       ` Danil Kipnis
2019-09-27 12:18                         ` Danil Kipnis
2019-09-27 16:37                       ` Bart Van Assche
2019-09-27 16:50                         ` Roman Penyaev
2019-09-27 17:16                           ` Bart Van Assche
2019-09-17 13:09     ` Jinpu Wang
2019-09-17 16:46       ` Bart Van Assche
2019-09-18 12:02         ` Jinpu Wang
2019-09-18 16:05     ` Jinpu Wang
2019-09-14  0:00   ` Bart Van Assche
     [not found] ` <20190620150337.7847-25-jinpuwang@gmail.com>
2019-09-13 23:58   ` [PATCH v4 24/25] ibnbd: a bit of documentation Bart Van Assche
2019-09-18 12:22     ` Jinpu Wang
     [not found] ` <20190620150337.7847-19-jinpuwang@gmail.com>
2019-09-18 16:28   ` [PATCH v4 18/25] ibnbd: client: sysfs interface functions Bart Van Assche
2019-09-19 15:55     ` Jinpu Wang
     [not found] ` <20190620150337.7847-21-jinpuwang@gmail.com>
2019-09-18 17:41   ` [PATCH v4 20/25] ibnbd: server: main functionality Bart Van Assche
2019-09-20  7:36     ` Danil Kipnis
2019-09-20 15:42       ` Bart Van Assche
2019-09-23 15:19         ` Danil Kipnis
     [not found] ` <20190620150337.7847-22-jinpuwang@gmail.com>
2019-09-18 21:46   ` [PATCH v4 21/25] ibnbd: server: functionality for IO submission to file or block dev Bart Van Assche
2019-09-26 14:04     ` Jinpu Wang [this message]
2019-09-26 15:11       ` Bart Van Assche
2019-09-26 15:25         ` Danil Kipnis
2019-09-26 15:29           ` Bart Van Assche
2019-09-26 15:38             ` Danil Kipnis
2019-09-26 15:42               ` Jinpu Wang
     [not found] ` <20190620150337.7847-3-jinpuwang@gmail.com>
2019-09-23 17:44   ` [PATCH v4 02/25] ibtrs: public interface header to establish RDMA connections Bart Van Assche
2019-09-25 10:20     ` Danil Kipnis
2019-09-25 15:38       ` Bart Van Assche
     [not found] ` <20190620150337.7847-7-jinpuwang@gmail.com>
2019-09-23 21:51   ` [PATCH v4 06/25] ibtrs: client: main functionality Bart Van Assche
2019-09-25 17:36     ` Danil Kipnis
2019-09-25 18:55       ` Bart Van Assche
2019-09-25 20:50         ` Danil Kipnis
2019-09-25 21:08           ` Bart Van Assche
2019-09-25 21:16             ` Bart Van Assche
2019-09-25 22:53             ` Danil Kipnis
2019-09-25 23:21               ` Bart Van Assche
2019-09-26  9:16                 ` Danil Kipnis
     [not found] ` <20190620150337.7847-4-jinpuwang@gmail.com>
2019-09-23 22:50   ` [PATCH v4 03/25] ibtrs: private headers with IBTRS protocol structs and helpers Bart Van Assche
2019-09-25 21:45     ` Danil Kipnis
2019-09-25 21:57       ` Bart Van Assche
2019-09-27  8:56     ` Jinpu Wang
     [not found] ` <20190620150337.7847-5-jinpuwang@gmail.com>
2019-09-23 23:03   ` [PATCH v4 04/25] ibtrs: core: lib functions shared between client and server modules Bart Van Assche
2019-09-27 10:13     ` Jinpu Wang
     [not found] ` <20190620150337.7847-6-jinpuwang@gmail.com>
2019-09-23 23:05   ` [PATCH v4 05/25] ibtrs: client: private header with client structs and functions Bart Van Assche
2019-09-27 10:18     ` Jinpu Wang
     [not found] ` <20190620150337.7847-8-jinpuwang@gmail.com>
2019-09-23 23:15   ` [PATCH v4 07/25] ibtrs: client: statistics functions Bart Van Assche
2019-09-27 12:00     ` Jinpu Wang
     [not found] ` <20190620150337.7847-10-jinpuwang@gmail.com>
2019-09-23 23:21   ` [PATCH v4 09/25] ibtrs: server: private header with server structs and functions Bart Van Assche
2019-09-27 12:04     ` Jinpu Wang
     [not found] ` <20190620150337.7847-11-jinpuwang@gmail.com>
2019-09-23 23:49   ` [PATCH v4 10/25] ibtrs: server: main functionality Bart Van Assche
2019-09-27 15:03     ` Jinpu Wang
2019-09-27 15:11       ` Bart Van Assche
2019-09-27 15:19         ` Jinpu Wang
     [not found] ` <20190620150337.7847-12-jinpuwang@gmail.com>
2019-09-23 23:56   ` [PATCH v4 11/25] ibtrs: server: statistics functions Bart Van Assche
2019-10-02 15:15     ` Jinpu Wang
2019-10-02 15:42       ` Leon Romanovsky
2019-10-02 15:45         ` Jinpu Wang
2019-10-02 16:00           ` Leon Romanovsky
     [not found] ` <20190620150337.7847-13-jinpuwang@gmail.com>
2019-09-24  0:00   ` [PATCH v4 12/25] ibtrs: server: sysfs interface functions Bart Van Assche
2019-10-02 15:11     ` Jinpu Wang

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