From: Christoph Hellwig <hch@lst.de>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v2 4/7] btrfs: introduce new read-repair infrastructure
Date: Thu, 26 May 2022 09:30:22 +0200 [thread overview]
Message-ID: <20220526073022.GA25511@lst.de> (raw)
In-Reply-To: <531d3865-eb5b-d114-9ff2-c1b209902262@suse.com>
On Thu, May 26, 2022 at 11:06:31AM +0800, Qu Wenruo wrote:
> Hi Christoph, I'm pretty sure the non-continuous bio problem is here for
> all of our attempts to rework read-repair.
Why is it a problem? Multiple discontiguous errors in the same bio
are a very unusual error pattern. We need to handle it obviously, but
it doesn't need to be optimized as it is so rare. The most common error
pattern is that the entire read will return an error, followed by a single
corrupted sector.
> I'm wondering if there is some "dummy" page provided from block layer that
> we can utilize?
For reads nvme (and a few SCSI HBAs) support a bit bucket SGL for reads
that discard parts of the data. Right now upstream none of this is
supported, altough Keith has been looking into it (for a rather different
use case) in nvme. This does not help with writes, never mind the fact
that I would not want to use exotic and barely tested code and hardware
features for a non time critical and rarely used error handling path..
next prev parent reply other threads:[~2022-05-26 7:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-25 10:59 [PATCH v2 0/7] btrfs: read-repair rework based on bitmap Qu Wenruo
2022-05-25 10:59 ` [PATCH v2 1/7] btrfs: save the original bi_iter into btrfs_bio for buffered read Qu Wenruo
2022-05-25 10:59 ` [PATCH v2 2/7] btrfs: make repair_io_failure available outside of extent_io.c Qu Wenruo
2022-05-25 10:59 ` [PATCH v2 3/7] btrfs: add a btrfs_map_bio_wait helper Qu Wenruo
2022-05-25 10:59 ` [PATCH v2 4/7] btrfs: introduce new read-repair infrastructure Qu Wenruo
2022-05-26 3:06 ` Qu Wenruo
2022-05-26 7:30 ` Christoph Hellwig [this message]
2022-05-26 7:37 ` Qu Wenruo
2022-05-26 7:45 ` Christoph Hellwig
2022-05-26 7:52 ` Qu Wenruo
2022-05-26 8:00 ` Christoph Hellwig
2022-05-26 8:07 ` Qu Wenruo
2022-05-26 8:17 ` Christoph Hellwig
2022-05-26 8:26 ` Qu Wenruo
2022-05-26 8:28 ` Christoph Hellwig
2022-05-26 8:49 ` Qu Wenruo
2022-05-26 8:54 ` Christoph Hellwig
2022-05-26 9:13 ` Qu Wenruo
2022-05-27 8:10 ` Christoph Hellwig
2022-05-25 10:59 ` [PATCH v2 5/7] btrfs: make buffered read path to use the new read repair infrastructure Qu Wenruo
2022-05-25 10:59 ` [PATCH v2 6/7] btrfs: make direct io " Qu Wenruo
2022-05-25 10:59 ` [PATCH v2 7/7] btrfs: remove io_failure_record infrastructure completely Qu Wenruo
2022-05-25 14:55 ` [PATCH v2 0/7] btrfs: read-repair rework based on bitmap David Sterba
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