linux-kernel - Re: [PATCH v2 08/17] fs: retrofit old error reporting API onto new infrastructure

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Message-ID: <87vaq2tzhu.fsf@notabene.neil.brown.name>
Date:   Tue, 18 Apr 2017 08:56:13 +1000
From:   NeilBrown <neilb@...e.com>
To:     Jeff Layton <jlayton@...hat.com>, linux-fsdevel@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        tytso@....edu, jack@...e.cz, willy@...radead.org,
        viro@...iv.linux.org.uk
Subject: Re: [PATCH v2 08/17] fs: retrofit old error reporting API onto new infrastructure

On Wed, Apr 12 2017, Jeff Layton wrote:

> On Thu, 2017-04-13 at 08:14 +1000, NeilBrown wrote:
>> 
>> I suspect that the filemap_check_wb_error() will need to be moved
>> into some parent of the current call site, which is essentially what you
>> suggest below.  It would be nice if we could do that first, rather than
>> having the current rather odd code.  But maybe this way is an easier
>> transition.  It isn't obviously wrong, it just isn't obviously right
>> either.
>> 
>
> Yeah. It's just such a daunting task to have to change so much of the
> existing code. I'm looking for ways to make this simpler.
>
> I think it probably is reasonable for filemap_write_and_wait* to just
> sample it as early as possible in those functions. filemap_fdatawait is
> the real questionable one, as you may have already had some writebacks
> complete with errors.
>
> In any case, my thinking was that the old code is not obviously correct
> either, so while this shortens the "error capture window" on these
> calls, it seems like a reasonable place to start improving things.

I agree.  It wouldn't hurt to add a note to this effect in the patch
comment so that people understand that the code isn't seen to be
"correct" but only "no worse" with clear direction on what sort of
improvement might be appropriate.

Thanks,
NeilBrown

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