From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 5/8] loop: fallback to buffered IO in case of dio submission
Date: Tue, 26 Oct 2021 09:36:58 +0200 [thread overview]
Message-ID: <20211026073658.GD31967@lst.de> (raw)
In-Reply-To: <20211025094437.2837701-6-ming.lei@redhat.com>
On Mon, Oct 25, 2021 at 05:44:34PM +0800, Ming Lei wrote:
> DIO submission on underlying file may fail because of unaligned buffer or
> start_sector & sector_length, fallback to buffered IO when that happens,
> this way will make loop dio mode more reliable.
I don't think this is a good idea. Just do an ahead of time check
that the alignment matches and don't even try to use direct I/O code
in that case. Otherwise we get a mix and match between buffered and
direct I/O, which is actively harmful.
next prev parent reply other threads:[~2021-10-26 7:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-25 9:44 [PATCH 0/8] loop: improve dio on backing file Ming Lei
2021-10-25 9:44 ` [PATCH 1/8] loop: move flush_dcache_page to ->complete of request Ming Lei
2021-10-26 7:21 ` Christoph Hellwig
2021-10-25 9:44 ` [PATCH 2/8] loop: remove always true check Ming Lei
2021-10-26 7:31 ` Christoph Hellwig
2021-10-25 9:44 ` [PATCH 3/8] loop: add one helper for submitting IO on backing file Ming Lei
2021-10-25 9:44 ` [PATCH 4/8] loop: cover simple read/write via lo_rw_aio() Ming Lei
2021-10-26 7:35 ` Christoph Hellwig
2021-10-25 9:44 ` [PATCH 5/8] loop: fallback to buffered IO in case of dio submission Ming Lei
2021-10-26 7:36 ` Christoph Hellwig [this message]
2021-10-25 9:44 ` [PATCH 6/8] loop: relax loop dio use condition Ming Lei
2021-10-26 7:37 ` Christoph Hellwig
2021-10-27 0:20 ` kernel test robot
2021-10-25 9:44 ` [PATCH 7/8] loop: remove lo->use_dio Ming Lei
2021-10-25 9:44 ` [RFC PATCH 8/8] loop: use backing dio at default Ming Lei
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