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From: Martijn Coenen <maco@android.com>
To: Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@infradead.org>,
	Ming Lei <ming.lei@redhat.com>
Cc: linux-block <linux-block@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	kernel-team@android.com, Narayan Kamath <narayan@google.com>,
	Dario Freni <dariofreni@google.com>,
	Nikita Ioffe <ioffe@google.com>, Jiyong Park <jiyong@google.com>,
	Martijn Coenen <maco@google.com>
Subject: Re: [PATCH v2] loop: change queue block size to match when using DIO.
Date: Tue, 10 Sep 2019 12:12:28 +0200	[thread overview]
Message-ID: <CAB0TPYHjPbzMNqS6wiYmjUjrmROSVVCYsSQLjwE+PUOBsMH_mw@mail.gmail.com> (raw)
In-Reply-To: <20190904194901.165883-1-maco@android.com>

Hi Jens, Ming,

Do you have any thoughts about this patch?

Thanks,
Martijn

On Wed, Sep 4, 2019 at 9:49 PM Martijn Coenen <maco@android.com> wrote:
>
> The loop driver assumes that if the passed in fd is opened with
> O_DIRECT, the caller wants to use direct I/O on the loop device.
> However, if the underlying block device has a different block size than
> the loop block queue, direct I/O can't be enabled. Instead of requiring
> userspace to manually change the blocksize and re-enable direct I/O,
> just change the queue block sizes to match, as well as the io_min size.
>
> Signed-off-by: Martijn Coenen <maco@android.com>
> ---
> v2 changes:
> - Fixed commit message to say the block size must match the underlying
>   block device, not the underlying filesystem.
> - Also set physical blocksize and minimal io size correspondingly.
>
>  drivers/block/loop.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index ab7ca5989097a..b547182037af2 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -994,6 +994,16 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
>         if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
>                 blk_queue_write_cache(lo->lo_queue, true, false);
>
> +       if (io_is_direct(lo->lo_backing_file) && inode->i_sb->s_bdev) {
> +               /* In case of direct I/O, match underlying block size */
> +               unsigned short bsize = bdev_logical_block_size(
> +                       inode->i_sb->s_bdev);
> +
> +               blk_queue_logical_block_size(lo->lo_queue, bsize);
> +               blk_queue_physical_block_size(lo->lo_queue, bsize);
> +               blk_queue_io_min(lo->lo_queue, bsize);
> +       }
> +
>         loop_update_rotational(lo);
>         loop_update_dio(lo);
>         set_capacity(lo->lo_disk, size);
> --
> 2.23.0.187.g17f5b7556c-goog
>

  reply	other threads:[~2019-09-10 10:12 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-28 10:32 [PATCH] loop: change queue block size to match when using DIO Martijn Coenen
2019-08-30 15:50 ` Christoph Hellwig
2019-09-02 19:37   ` Martijn Coenen
2019-09-04 19:49 ` [PATCH v2] " Martijn Coenen
2019-09-10 10:12   ` Martijn Coenen [this message]
2019-09-30  8:24   ` Christoph Hellwig
2019-10-01 10:03     ` Martijn Coenen
2019-10-01 14:10   ` Jens Axboe

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