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Groups > linux.kernel > #1210124

Re: [PATCH 2/2] ubifs: Allow O_DIRECT

From Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Newsgroups linux.kernel
Subject Re: [PATCH 2/2] ubifs: Allow O_DIRECT
Date 2015-08-20 05:10 +0200
Message-ID <pZooN-tt-1@gated-at.bofh.it> (permalink)
References <pZijn-8mM-15@gated-at.bofh.it> <pZijn-8mM-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 08/20/2015 04:35 AM, Richard Weinberger wrote:
> Currently UBIFS does not support direct IO, but some applications
> blindly use the O_DIRECT flag.
> Instead of failing upon open() we can do better and fall back
> to buffered IO.

Hmmmm, to be honest, I am not sure we have to do it as Dave
suggested. I think that's just a work-around for current fstests.

IMHO, perform a buffered IO when user request direct IO without
any warning sounds not a good idea. Maybe adding a warning would
make it better.

I think we need more discussion about AIO&DIO in ubifs, and actually
I have a plan for it. But I have not listed the all cons and pros of
it so far.

Artem, what's your opinion?

Yang
>
> Cc: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
> Cc: dedekind1@gmail.com
> Suggested-by: Dave Chinner <david@fromorbit.com>
> Signed-off-by: Richard Weinberger <richard@nod.at>
> ---
>   fs/ubifs/file.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
>
> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index a3dfe2a..a61fe86 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -1540,6 +1540,15 @@ static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)
>   	return 0;
>   }
>
> +/*
> + * For now fall back to buffered IO.
> + */
> +static ssize_t ubifs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
> +				   loff_t offset)
> +{
> +	return 0;
> +}
> +
>   const struct address_space_operations ubifs_file_address_operations = {
>   	.readpage       = ubifs_readpage,
>   	.writepage      = ubifs_writepage,
> @@ -1548,6 +1557,7 @@ const struct address_space_operations ubifs_file_address_operations = {
>   	.invalidatepage = ubifs_invalidatepage,
>   	.set_page_dirty = ubifs_set_page_dirty,
>   	.releasepage    = ubifs_releasepage,
> +	.direct_IO	= ubifs_direct_IO,
>   };
>
>   const struct inode_operations ubifs_file_inode_operations = {
>

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Thread

[PATCH 2/2] ubifs: Allow O_DIRECT Richard Weinberger <richard@nod.at> - 2015-08-19 22:40 +0200
  Re: [PATCH 2/2] ubifs: Allow O_DIRECT Dongsheng Yang <yangds.fnst@cn.fujitsu.com> - 2015-08-20 05:10 +0200
    Re: [PATCH 2/2] ubifs: Allow O_DIRECT Richard Weinberger <richard@nod.at> - 2015-08-20 08:50 +0200
      Re: [PATCH 2/2] ubifs: Allow O_DIRECT Dongsheng Yang <yangds.fnst@cn.fujitsu.com> - 2015-08-20 09:30 +0200
    Re: [PATCH 2/2] ubifs: Allow O_DIRECT Artem Bityutskiy <dedekind1@gmail.com> - 2015-08-20 13:40 +0200
      Re: [PATCH 2/2] ubifs: Allow O_DIRECT Richard Weinberger <richard@nod.at> - 2015-08-20 13:50 +0200
        Re: [PATCH 2/2] ubifs: Allow O_DIRECT Artem Bityutskiy <dedekind1@gmail.com> - 2015-08-20 14:40 +0200
          Re: [PATCH 2/2] ubifs: Allow O_DIRECT Artem Bityutskiy <dedekind1@gmail.com> - 2015-08-24 09:20 +0200
            Re: [PATCH 2/2] ubifs: Allow O_DIRECT Dongsheng Yang <yangds.fnst@cn.fujitsu.com> - 2015-08-24 09:30 +0200
            Re: [PATCH 2/2] ubifs: Allow O_DIRECT Dongsheng Yang <yangds.fnst@cn.fujitsu.com> - 2015-08-24 09:30 +0200
              Re: [PATCH 2/2] ubifs: Allow O_DIRECT Christoph Hellwig <hch@infradead.org> - 2015-08-24 10:10 +0200
        Re: [PATCH 2/2] ubifs: Allow O_DIRECT Brian Norris <computersforpeace@gmail.com> - 2015-08-20 23:00 +0200
          Re: [PATCH 2/2] ubifs: Allow O_DIRECT Artem Bityutskiy <dedekind1@gmail.com> - 2015-08-24 09:20 +0200
            Re: [PATCH 2/2] ubifs: Allow O_DIRECT Christoph Hellwig <hch@infradead.org> - 2015-08-24 10:00 +0200
              Re: [PATCH 2/2] ubifs: Allow O_DIRECT Christoph Hellwig <hch@infradead.org> - 2015-08-24 10:10 +0200
                Re: [PATCH 2/2] ubifs: Allow O_DIRECT Dongsheng Yang <yangds.fnst@cn.fujitsu.com> - 2015-08-24 10:10 +0200
                Re: [PATCH 2/2] ubifs: Allow O_DIRECT Richard Weinberger <richard@nod.at> - 2015-08-24 11:40 +0200
                Re: [PATCH 2/2] ubifs: Allow O_DIRECT Artem Bityutskiy <dedekind1@gmail.com> - 2015-08-24 11:40 +0200
              Re: [PATCH 2/2] ubifs: Allow O_DIRECT Artem Bityutskiy <dedekind1@gmail.com> - 2015-08-24 10:10 +0200
            Re: [PATCH 2/2] ubifs: Allow O_DIRECT Brian Norris <computersforpeace@gmail.com> - 2015-08-24 18:20 +0200
              Re: [PATCH 2/2] ubifs: Allow O_DIRECT Jeff Moyer <jmoyer@redhat.com> - 2015-08-24 19:20 +0200
                Re: [PATCH 2/2] ubifs: Allow O_DIRECT Dave Chinner <david@fromorbit.com> - 2015-08-25 01:50 +0200
                Re: [PATCH 2/2] ubifs: Allow O_DIRECT Chris Mason <clm@fb.com> - 2015-08-25 03:30 +0200
                Re: [PATCH 2/2] ubifs: Allow O_DIRECT Artem Bityutskiy <dedekind1@gmail.com> - 2015-08-25 17:50 +0200
                Re: [PATCH 2/2] ubifs: Allow O_DIRECT Jeff Moyer <jmoyer@redhat.com> - 2015-08-25 16:10 +0200
                Re: [PATCH 2/2] ubifs: Allow O_DIRECT Jeff Moyer <jmoyer@redhat.com> - 2015-08-25 16:20 +0200
                Re: [PATCH 2/2] ubifs: Allow O_DIRECT Chris Mason <clm@fb.com> - 2015-08-25 16:20 +0200
  Re: [PATCH 2/2] ubifs: Allow O_DIRECT Artem Bityutskiy <dedekind1@gmail.com> - 2015-08-20 13:30 +0200

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