From: Christoph Hellwig <hch@infradead.org>
To: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>,
Josef Bacik <josef@toxicpanda.com>,
linux-btrfs@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 00/17] btrfs: restrain lock extent usage during writeback
Date: Thu, 18 Apr 2024 07:47:26 -0700 [thread overview]
Message-ID: <ZiEyfvCOrlsIgtiR@infradead.org> (raw)
In-Reply-To: <qjy6xzmwpggluuwbgu4aljweoiwnrowvgklw6trn6tvwyk4wqi@akofzgx2tnms>
On Thu, Apr 18, 2024 at 08:45:35AM -0500, Goldwyn Rodrigues wrote:
> The only reason I have encountered for taking extent locks during reads
> is for checksums. read()s collects checksums before submitting the bio
> where as writeback() adds the checksums during bio completion.
>
> So, there is a small window where a read() performed immediately after
> writeback+truncate pages would give an EIO because the checksum is
> not in the checksum tree and does not match the calculated checksum.
>
> If we can delay retrieving the checksum or wait for ordered extents to
> complete before performing the read, I think avoiding extent locks
> during read is possible.
And the fix for that is to only clear the writeback bit once the
ordered extent processing has finished, which is the other bit
making btrfs I/O so different from the core kernels expectations.
It is highly coupled with the extent lock semantics as far as I
can tell.
next prev parent reply other threads:[~2024-04-18 14:47 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-17 14:35 [PATCH 00/17] btrfs: restrain lock extent usage during writeback Josef Bacik
2024-04-17 14:35 ` [PATCH 01/17] btrfs: handle errors in btrfs_reloc_clone_csums properly Josef Bacik
2024-04-17 16:01 ` Johannes Thumshirn
2024-04-29 14:38 ` David Sterba
2024-04-17 14:35 ` [PATCH 02/17] btrfs: push all inline logic into cow_file_range Josef Bacik
2024-04-24 17:23 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 03/17] btrfs: unlock all the pages with successful inline extent creation Josef Bacik
2024-04-17 16:14 ` Johannes Thumshirn
2024-04-17 14:35 ` [PATCH 04/17] btrfs: move extent bit and page cleanup into cow_file_range_inline Josef Bacik
2024-04-17 16:24 ` Johannes Thumshirn
2024-04-17 14:35 ` [PATCH 05/17] btrfs: lock extent when doing inline extent in compression Josef Bacik
2024-04-17 16:29 ` Johannes Thumshirn
2024-04-19 18:52 ` Josef Bacik
2024-04-17 14:35 ` [PATCH 06/17] btrfs: push the extent lock into btrfs_run_delalloc_range Josef Bacik
2024-04-24 17:26 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 07/17] btrfs: push extent lock into run_delalloc_nocow Josef Bacik
2024-04-23 11:33 ` Goldwyn Rodrigues
2024-04-23 16:49 ` Josef Bacik
2024-04-24 12:28 ` David Sterba
2024-04-24 17:53 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 08/17] btrfs: adjust while loop condition in run_delalloc_nocow Josef Bacik
2024-04-18 14:05 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 09/17] btrfs: push extent lock down " Josef Bacik
2024-04-24 17:41 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 10/17] btrfs: remove unlock_extent from run_delalloc_compressed Josef Bacik
2024-04-24 17:43 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 11/17] btrfs: push extent lock into run_delalloc_cow Josef Bacik
2024-04-24 17:45 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 12/17] btrfs: push extent lock into cow_file_range Josef Bacik
2024-04-24 17:46 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 13/17] btrfs: push lock_extent into cow_file_range_inline Josef Bacik
2024-04-24 17:48 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 14/17] btrfs: move can_cow_file_range_inline() outside of the extent lock Josef Bacik
2024-04-23 11:38 ` Goldwyn Rodrigues
2024-04-17 14:35 ` [PATCH 15/17] btrfs: push lock_extent down in cow_file_range() Josef Bacik
2024-04-24 17:49 ` Goldwyn Rodrigues
2024-04-17 14:36 ` [PATCH 16/17] btrfs: push extent lock down in submit_one_async_extent Josef Bacik
2024-04-23 11:39 ` Goldwyn Rodrigues
2024-04-17 14:36 ` [PATCH 17/17] btrfs: add a cached state to extent_clear_unlock_delalloc Josef Bacik
2024-04-23 11:42 ` Goldwyn Rodrigues
2024-04-24 17:21 ` Goldwyn Rodrigues
2024-04-18 5:54 ` [PATCH 00/17] btrfs: restrain lock extent usage during writeback Christoph Hellwig
2024-04-18 13:45 ` Goldwyn Rodrigues
2024-04-18 14:47 ` Christoph Hellwig [this message]
2024-04-19 18:54 ` Josef Bacik
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