From: Christoph Hellwig <hch@lst.de>
To: 0wnerD1ed <l7z@0b1t.tech>
Cc: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>,
Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Christian Brauner <brauner@kernel.org>,
"Darrick J. Wong" <djwong@kernel.org>,
Carlos Maiolino <cem@kernel.org>,
Tal Zussman <tz2294@columbia.edu>,
Anuj Gupta <anuj20.g@samsung.com>,
linux-block@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 13/16] xfs: add support for lazy direct read bounce buffering
Date: Mon, 21 Sep 2026 10:22:40 +0200 [thread overview]
Message-ID: <20260921082240.GA19833@lst.de> (raw)
In-Reply-To: <CAKTh27_szTVmVmV26ASynzdJUwQEe49wCxMNq5ifRH9z7tiykA@mail.gmail.com>
On Mon, Sep 21, 2026 at 04:05:52PM +0800, 0wnerD1ed wrote:
> Thanks for the report. I've taken a look at the v3 series. block/046
> deliberately uses iovec lengths of 1, one logical block, and one logical
> block minus 1 to create the partial extraction state that exposed the
> original double unpin.
>
> Patch 13 stops passing IOMAP_DIO_BOUNCE to iomap_dio_rw(), so the
> request now goes through the ordinary bio_iov_iter_get_pages() path
> first. That path validates each iovec against bdev_dma_alignment(),
> and the one-byte first iovec is rejected with EINVAL before it is
> pinned and before xfs_ioend_submit_read() can select lazy or always
> bounce mode.
Yeah, and this is supposed to be rejected.
> Setting csum/read_bounce to always therefore would not make this
> particular request reach the new bounce implementation. Patch 16 also
> removes bio_iov_iter_bounce_read(), including the special bvec layout
> that block/046 was written to exercise. Changing the helper to use
> aligned input and forcing always mode would test the replacement iomap
> implementation, but it would not preserve coverage of the original
> regression.
>
> I have prepared a minimal local blktests change that keeps block/046
> active on kernels using the legacy implementation and marks it not run
> when the mounted XFS instance exposes the new csum/read_bounce
> interface. That preserves the existing fixed-versus-vulnerable
> coverage without treating EINVAL as a successful result. A separate
> test could cover the new lazy and always implementations with aligned
> input and an oracle appropriate to those paths.
Sounds good, although trying to exploit things with two small bio_vec
in general sounds like a good idea..
next prev parent reply other threads:[~2026-09-21 8:22 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-09 6:08 lazy bounce buffering for checksummed reads v3 Christoph Hellwig
2026-09-09 6:08 ` [PATCH 01/16] block: split bio_iov_iter_bounce_write Christoph Hellwig
2026-09-11 16:41 ` Jens Axboe
2026-09-09 6:08 ` [PATCH 02/16] block: export fs_bio_integrity_{alloc,free} Christoph Hellwig
2026-09-09 6:08 ` [PATCH 03/16] block: add a bio_prepare_reissue helper Christoph Hellwig
2026-09-09 16:05 ` Darrick J. Wong
2026-09-09 6:08 ` [PATCH 04/16] iomap: respect maximum I/O size in iomap_dio_bio_iter_one Christoph Hellwig
2026-09-09 6:08 ` [PATCH 05/16] iomap: add a iomap_ioend_flags helper Christoph Hellwig
2026-09-09 6:08 ` [PATCH 06/16] iomap: add a IOMAP_IOEND_INTEGRITY flag Christoph Hellwig
2026-09-09 6:08 ` [PATCH 07/16] iomap,xfs: move T10 PI handling for direct I/O into ->submit_io Christoph Hellwig
2026-09-09 6:08 ` [PATCH 08/16] xfs: move PI generation into xfs_submit_zoned_bio Christoph Hellwig
2026-09-09 16:06 ` Darrick J. Wong
2026-09-09 6:08 ` [PATCH 09/16] block,iomap: fix protection information verification with initial bvec offset Christoph Hellwig
2026-09-09 6:08 ` [PATCH 10/16] iomap: better read bounce buffering support Christoph Hellwig
2026-09-09 6:09 ` [PATCH 11/16] xfs: use BIO_COMPLETE_IN_TASK for bounce buffered read I/Os Christoph Hellwig
2026-09-09 6:09 ` [PATCH 12/16] iomap,xfs: move integrity verification to the file system Christoph Hellwig
2026-09-09 6:09 ` [PATCH 13/16] xfs: add support for lazy direct read bounce buffering Christoph Hellwig
2026-09-21 6:40 ` Shin'ichiro Kawasaki
2026-09-21 7:10 ` Christoph Hellwig
2026-09-21 8:05 ` 0wnerD1ed
2026-09-21 8:22 ` Christoph Hellwig [this message]
2026-09-09 6:09 ` [PATCH 14/16] xfs: add error injection for lazy " Christoph Hellwig
2026-09-09 6:09 ` [PATCH 15/16] xfs: log a message at mount time when using integrity protection Christoph Hellwig
2026-09-09 6:09 ` [PATCH 16/16] block,iomap: remove the old read side bounce buffering support Christoph Hellwig
2026-09-09 16:15 ` Darrick J. Wong
2026-09-10 20:50 ` lazy bounce buffering for checksummed reads v3 Jens Axboe
2026-09-10 20:51 ` Jens Axboe
2026-09-11 11:44 ` Christoph Hellwig
2026-09-11 13:38 ` Jens Axboe
2026-09-11 3:57 ` Anuj gupta
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