From: Michal Hocko <mhocko@kernel.org>
To: Jiri Kosina <jikos@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-api@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
Greg KH <gregkh@linuxfoundation.org>,
Jann Horn <jannh@google.com>,
Dominique Martinet <asmadeus@codewreck.org>,
Andy Lutomirski <luto@amacapital.net>,
Dave Chinner <david@fromorbit.com>,
Kevin Easton <kevin@guarana.org>,
Matthew Wilcox <willy@infradead.org>,
Cyril Hrubis <chrubis@suse.cz>, Tejun Heo <tj@kernel.org>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Daniel Gruss <daniel@gruss.cc>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/3] mm/filemap: initiate readahead even if IOCB_NOWAIT is set for the I/O
Date: Thu, 31 Jan 2019 11:23:48 +0100 [thread overview]
Message-ID: <20190131102348.GT18811@dhcp22.suse.cz> (raw)
In-Reply-To: <nycvar.YFH.7.76.1901311114260.6626@cbobk.fhfr.pm>
On Thu 31-01-19 11:15:28, Jiri Kosina wrote:
> On Thu, 31 Jan 2019, Michal Hocko wrote:
>
> > > diff --git a/mm/filemap.c b/mm/filemap.c
> > > index 9f5e323e883e..7bcdd36e629d 100644
> > > --- a/mm/filemap.c
> > > +++ b/mm/filemap.c
> > > @@ -2075,8 +2075,6 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
> > >
> > > page = find_get_page(mapping, index);
> > > if (!page) {
> > > - if (iocb->ki_flags & IOCB_NOWAIT)
> > > - goto would_block;
> > > page_cache_sync_readahead(mapping,
> > > ra, filp,
> > > index, last_index - index);
> >
> > Maybe a stupid question but I am not really familiar with this path but
> > what exactly does prevent a sync read down page_cache_sync_readahead
> > path?
>
> page_cache_sync_readahead() only submits the read ahead request(s), it
> doesn't wait for it to finish.
OK, I guess my question was not precise. What does prevent taking fs
locks down the path?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-01-31 10:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <nycvar.YFH.7.76.1901051817390.16954@cbobk.fhfr.pm>
[not found] ` <20190130124420.1834-1-vbabka@suse.cz>
[not found] ` <20190130124420.1834-3-vbabka@suse.cz>
2019-01-31 9:56 ` [PATCH 2/3] mm/filemap: initiate readahead even if IOCB_NOWAIT is set for the I/O Michal Hocko
2019-01-31 10:15 ` Jiri Kosina
2019-01-31 10:23 ` Michal Hocko [this message]
2019-01-31 10:30 ` Jiri Kosina
2019-01-31 11:32 ` Michal Hocko
2019-01-31 17:54 ` Linus Torvalds
2019-02-01 5:13 ` Dave Chinner
2019-02-01 7:05 ` Linus Torvalds
2019-02-01 7:21 ` Linus Torvalds
2019-02-01 1:44 ` Dave Chinner
2019-02-12 15:48 ` Jiri Kosina
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