Re: [Lsf-pc] [LSF/MM TOPIC] do we really need PG_error at all?

From	Boaz Harrosh <openosd@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [Lsf-pc] [LSF/MM TOPIC] do we really need PG_error at all?
Date	2017-02-28 11:20 +0100
Message-ID	<tfN2W-32f-11@gated-at.bofh.it> (permalink)
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On 02/28/2017 03:11 AM, Jeff Layton wrote:
<>
> 
> I'll probably have questions about the read side as well, but for now it
> looks like it's mostly used in an ad-hoc way to communicate errors
> across subsystems (block to fs layer, for instance).

If memory does not fail me it used to be checked long time ago in the
read-ahead case. On the buffered read case, the first page is read synchronous
and any error is returned to the caller, but then a read-ahead chunk is
read async all the while the original thread returned to the application.
So any errors are only recorded on the page-bit, since otherwise the uptodate
is off and the IO will be retransmitted. Then the move to read_iter changed
all that I think.
But again this is like 5-6 years ago, and maybe I didn't even understand
very well.

> --
> Jeff Layton <jlayton@redhat.com>
> 

I would like a Documentation of all this as well please. Where are the
tests for this?

Thanks
Boaz

Thread

[LSF/MM TOPIC] do we really need PG_error at all? Jeff Layton <jlayton@redhat.com> - 2017-02-26 15:50 +0100
  Re: [LSF/MM TOPIC] do we really need PG_error at all? James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-02-26 18:30 +0100
    Re: [LSF/MM TOPIC] do we really need PG_error at all? NeilBrown <neilb@suse.com> - 2017-02-26 22:30 +0100
      Re: [LSF/MM TOPIC] do we really need PG_error at all? Jeff Layton <jlayton@redhat.com> - 2017-02-26 23:50 +0100
      Re: [LSF/MM TOPIC] do we really need PG_error at all? James Bottomley <James.Bottomley@HansenPartnership.com> - 2017-02-27 00:50 +0100
        Re: [LSF/MM TOPIC] do we really need PG_error at all? Jeff Layton <jlayton@redhat.com> - 2017-02-27 01:00 +0100
        Re: [LSF/MM TOPIC] do we really need PG_error at all? NeilBrown <neilb@suse.com> - 2017-02-27 01:30 +0100
          Re: [LSF/MM TOPIC] do we really need PG_error at all? Jeff Layton <jlayton@redhat.com> - 2017-02-27 16:10 +0100
            Re: [LSF/MM TOPIC] do we really need PG_error at all? NeilBrown <neilb@suse.com> - 2017-02-28 00:40 +0100
              Re: [Lsf-pc] [LSF/MM TOPIC] do we really need PG_error at all? Jeff Layton <jlayton@redhat.com> - 2017-02-28 02:30 +0100
                Re: [Lsf-pc] [LSF/MM TOPIC] do we really need PG_error at all? Boaz Harrosh <openosd@gmail.com> - 2017-02-28 11:20 +0100
                Re: [Lsf-pc] [LSF/MM TOPIC] do we really need PG_error at all? Jeff Layton <jlayton@redhat.com> - 2017-02-28 12:40 +0100
                Re: [Lsf-pc] [LSF/MM TOPIC] do we really need PG_error at all? NeilBrown <neilb@suse.com> - 2017-02-28 22:10 +0100
            Re: [LSF/MM TOPIC] do we really need PG_error at all? Andreas Dilger <adilger@dilger.ca> - 2017-02-28 02:00 +0100
              Re: [LSF/MM TOPIC] do we really need PG_error at all? Jeff Layton <jlayton@redhat.com> - 2017-02-28 02:10 +0100

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