From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Kiryl Shutsemau <kirill@shutemov.name>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
Suren Baghdasaryan <surenb@google.com>
Subject: Re: [PATCH] mm/filemap: Implement fast short reads
Date: Tue, 21 Oct 2025 18:25:30 -1000 [thread overview]
Message-ID: <CAHk-=wjaR_v5Gc_SUGkiz39_hiRHb-AEChknoAu9BUrQRSznAw@mail.gmail.com> (raw)
In-Reply-To: <aPgZthYaP7Flda0z@dread.disaster.area>
On Tue, 21 Oct 2025 at 13:39, Dave Chinner <david@fromorbit.com> wrote:
>
> > > > 1. Locate a folio in XArray.
> > > > 2. Obtain a reference on the folio using folio_try_get().
> > > > 3. If successful, verify that the folio still belongs to
> > > > the mapping and has not been truncated or reclaimed.
>
> What about if it has been hole-punched?
The sequence number check should take care of anything like that. Do
you have any reason to believe it doesn't?
Yes, you can get the "before or after or between" behavior, but you
can get that with perfectly regular reads that take the refcount on
the page.
Reads have never taken the page lock, and have never been serialized that way.
So the fast case changes absolutely nothing in this respect that I can see.
Linus
next prev parent reply other threads:[~2025-10-22 4:25 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-17 14:15 Kiryl Shutsemau
2025-10-18 2:38 ` kernel test robot
2025-10-18 3:54 ` kernel test robot
2025-10-18 4:46 ` kernel test robot
2025-10-18 17:56 ` Linus Torvalds
2025-10-20 11:03 ` Kiryl Shutsemau
2025-10-20 4:53 ` Andrew Morton
2025-10-20 11:33 ` Kiryl Shutsemau
2025-10-21 15:50 ` Linus Torvalds
2025-10-21 23:39 ` Dave Chinner
2025-10-22 4:25 ` Linus Torvalds [this message]
2025-10-22 8:00 ` Dave Chinner
2025-10-22 15:31 ` Linus Torvalds
2025-10-23 7:50 ` Dave Chinner
2025-10-23 9:37 ` Jan Kara
2025-10-21 15:47 ` Linus Torvalds
2025-10-22 7:08 ` Pedro Falcato
2025-10-22 7:13 ` Linus Torvalds
2025-10-22 7:38 ` Pedro Falcato
2025-10-22 10:00 ` Kiryl Shutsemau
2025-10-22 17:28 ` David Hildenbrand
2025-10-23 10:31 ` Kiryl Shutsemau
2025-10-23 10:54 ` David Hildenbrand
2025-10-23 11:09 ` Kiryl Shutsemau
2025-10-23 12:08 ` David Hildenbrand
2025-10-23 11:10 ` David Hildenbrand
2025-10-23 11:11 ` David Hildenbrand
2025-10-23 11:40 ` Kiryl Shutsemau
2025-10-23 11:49 ` David Hildenbrand
2025-10-23 12:41 ` Kiryl Shutsemau
2025-10-23 17:42 ` Yang Shi
2025-10-27 10:49 ` Hugh Dickins
2025-10-27 15:50 ` Linus Torvalds
2025-10-27 16:06 ` David Hildenbrand
2025-10-27 16:48 ` Linus Torvalds
2025-10-27 16:53 ` David Hildenbrand
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