From: Matthew Wilcox <willy@infradead.org>
To: Joanne Koong <joannelkoong@gmail.com>
Cc: Brian Foster <bfoster@redhat.com>,
brauner@kernel.org, miklos@szeredi.hu, djwong@kernel.org,
hch@infradead.org, hsiangkao@linux.alibaba.com,
linux-block@vger.kernel.org, gfs2@lists.linux.dev,
linux-fsdevel@vger.kernel.org, kernel-team@meta.com,
linux-xfs@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH v5 07/14] iomap: track pending read bytes more optimally
Date: Fri, 24 Oct 2025 18:21:14 +0100 [thread overview]
Message-ID: <aPu1ilw6Tq6tKPrf@casper.infradead.org> (raw)
In-Reply-To: <CAJnrk1b3bHYhbW9q0r4A0NjnMNEbtCFExosAL_rUoBupr1mO3Q@mail.gmail.com>
On Fri, Oct 24, 2025 at 09:25:13AM -0700, Joanne Koong wrote:
> What I missed was that if all the bytes in the folio are non-uptodate
> and need to read in by the filesystem, then there's a bug where the
> read will be ended on the folio twice (in iomap_read_end() and when
> the filesystem calls iomap_finish_folio_write(), when only the
> filesystem should end the read), which does 2 folio unlocks which ends
> up locking the folio. Looking at the writeback patch that does a
> similar optimization [1], I miss the same thing there.
folio_unlock() contains:
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
Feels like more filesystem people should be enabling CONFIG_DEBUG_VM
when testing (excluding performance testing of course; it'll do ugly
things to your performance numbers).
next prev parent reply other threads:[~2025-10-24 17:21 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-26 0:25 [PATCH v5 00/14] fuse: use iomap for buffered reads + readahead Joanne Koong
2025-09-26 0:25 ` [PATCH v5 01/14] iomap: move bio read logic into helper function Joanne Koong
2025-09-26 0:25 ` [PATCH v5 02/14] iomap: move read/readahead bio submission " Joanne Koong
2025-09-26 0:25 ` [PATCH v5 03/14] iomap: store read/readahead bio generically Joanne Koong
2025-09-26 0:25 ` [PATCH v5 04/14] iomap: iterate over folio mapping in iomap_readpage_iter() Joanne Koong
2025-09-26 0:26 ` [PATCH v5 05/14] iomap: rename iomap_readpage_iter() to iomap_read_folio_iter() Joanne Koong
2025-09-26 0:26 ` [PATCH v5 06/14] iomap: rename iomap_readpage_ctx struct to iomap_read_folio_ctx Joanne Koong
2025-09-26 0:26 ` [PATCH v5 07/14] iomap: track pending read bytes more optimally Joanne Koong
2025-10-23 19:34 ` Brian Foster
2025-10-24 0:01 ` Joanne Koong
2025-10-24 16:25 ` Joanne Koong
2025-10-24 17:14 ` Brian Foster
2025-10-24 19:48 ` Joanne Koong
2025-10-24 21:55 ` Joanne Koong
2025-10-27 12:16 ` Brian Foster
2025-10-24 17:21 ` Matthew Wilcox [this message]
2025-10-24 19:22 ` Joanne Koong
2025-10-24 20:59 ` Matthew Wilcox
2025-10-24 21:37 ` Darrick J. Wong
2025-10-24 21:58 ` Joanne Koong
2025-09-26 0:26 ` [PATCH v5 08/14] iomap: set accurate iter->pos when reading folio ranges Joanne Koong
2025-09-26 0:26 ` [PATCH v5 09/14] iomap: add caller-provided callbacks for read and readahead Joanne Koong
2025-09-26 0:26 ` [PATCH v5 10/14] iomap: move buffered io bio logic into new file Joanne Koong
2025-09-26 0:26 ` [PATCH v5 11/14] iomap: make iomap_read_folio() a void return Joanne Koong
2025-09-26 0:26 ` [PATCH v5 12/14] fuse: use iomap for read_folio Joanne Koong
2025-09-26 0:26 ` [PATCH v5 13/14] fuse: use iomap for readahead Joanne Koong
2025-09-26 0:26 ` [PATCH v5 14/14] fuse: remove fc->blkbits workaround for partial writes Joanne Koong
2025-09-29 9:38 ` [PATCH v5 00/14] fuse: use iomap for buffered reads + readahead Christian Brauner
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