From: Christoph Hellwig <hch@infradead.org>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 05/13] btrfs: add btrfs_read_repair_ctrl to record corrupted sectors
Date: Tue, 3 May 2022 08:06:19 -0700 [thread overview]
Message-ID: <YnFE62oGR5C/8UN2@infradead.org> (raw)
In-Reply-To: <3f9b82f1bcc955fbb689a469e749cf1534857ea1.1651559986.git.wqu@suse.com>
On Tue, May 03, 2022 at 02:49:49PM +0800, Qu Wenruo wrote:
> - For the extra bitmaps
> We use btrfs_bio::read_repair_{cur|prev}_bitmap.
> This will add extra 16 bytes to btrfs_bio.
>
> This is unavoidable, or we need to allocate extra memory at endio
> function which can be dead lock prone.
>
> Furthermore, pre-allocating bitmap has a hidden benefit, if we're
> submitting a large read and failed to allocated enough memory for
> bitmap, we fail the bio, and VFS layer will automatically retry
> with smaller read range, giving us a higher chance to succeed in
> next try.
This is a really bad idea. Now every read needs to pay the quite
large price for corner case of a read repair. As I mentioned last time
I think a mempool with a few entries that any read repair can dip into
is a much better choice here.
next prev parent reply other threads:[~2022-05-03 15:06 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-03 6:49 [PATCH 00/13] btrfs: make read repair work in synchronous mode Qu Wenruo
2022-05-03 6:49 ` [PATCH 01/13] btrfs: introduce a pure data checksum checking helper Qu Wenruo
2022-05-03 15:03 ` Christoph Hellwig
2022-05-03 6:49 ` [PATCH 02/13] btrfs: quit early if the fs has no RAID56 support for raid56 related checks Qu Wenruo
2022-05-03 6:49 ` [PATCH 03/13] btrfs: save the original bi_iter into btrfs_bio for buffered read Qu Wenruo
2022-05-03 6:49 ` [PATCH 04/13] btrfs: remove duplicated parameters from submit_data_read_repair() Qu Wenruo
2022-05-03 6:49 ` [PATCH 05/13] btrfs: add btrfs_read_repair_ctrl to record corrupted sectors Qu Wenruo
2022-05-03 15:06 ` Christoph Hellwig [this message]
2022-05-04 1:12 ` Qu Wenruo
2022-05-04 14:05 ` Christoph Hellwig
2022-05-04 22:40 ` Qu Wenruo
2022-05-12 17:16 ` David Sterba
2022-05-13 10:33 ` Christoph Hellwig
2022-05-13 10:53 ` Qu Wenruo
2022-05-13 10:57 ` Christoph Hellwig
2022-05-13 11:21 ` Qu Wenruo
2022-05-13 11:23 ` Christoph Hellwig
2022-05-17 13:32 ` Qu Wenruo
2022-05-03 6:49 ` [PATCH 06/13] btrfs: add a helper to queue a corrupted sector for read repair Qu Wenruo
2022-05-03 15:07 ` Christoph Hellwig
2022-05-04 1:13 ` Qu Wenruo
2022-05-04 14:06 ` Christoph Hellwig
2022-05-12 17:20 ` David Sterba
2022-05-03 6:49 ` [PATCH 07/13] btrfs: introduce a helper to repair from one mirror Qu Wenruo
2022-05-03 6:49 ` [PATCH 08/13] btrfs: allow btrfs read repair to submit writes in asynchronous mode Qu Wenruo
2022-05-03 6:49 ` [PATCH 09/13] btrfs: handle RAID56 read repair differently Qu Wenruo
2022-05-03 6:49 ` [PATCH 10/13] btrfs: switch buffered read to the new read repair routine Qu Wenruo
2022-05-03 6:49 ` [PATCH 11/13] btrfs: switch direct IO routine to use btrfs_read_repair_ctrl Qu Wenruo
2022-05-03 6:49 ` [PATCH 12/13] btrfs: remove io_failure_record infrastructure completely Qu Wenruo
2022-05-03 6:49 ` [PATCH 13/13] btrfs: remove btrfs_inode::io_failure_tree Qu Wenruo
2022-05-03 15:07 ` Christoph Hellwig
2022-05-12 17:08 ` [PATCH 00/13] btrfs: make read repair work in synchronous mode David Sterba
2022-05-12 23:01 ` Qu Wenruo
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