From: Nikolay Borisov <nborisov@suse.com>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>, Qu Wenruo <wqu@suse.com>,
linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2 15/24] btrfs: extent-io: make type of extent_state::state to be at least 32 bits
Date: Thu, 19 Nov 2020 09:18:18 +0200 [thread overview]
Message-ID: <5910d5cf-581b-1c70-40fd-e6f3df0129b3@suse.com> (raw)
In-Reply-To: <a2ac82fa-bcf8-a54c-181b-9492893aa6a3@gmx.com>
On 19.11.20 г. 1:48 ч., Qu Wenruo wrote:
>
>
> On 2020/11/19 上午12:11, David Sterba wrote:
>> On Fri, Nov 13, 2020 at 08:51:40PM +0800, Qu Wenruo wrote:
>>> Currently we use 'unsigned' for extent_state::state, which is only ensured
>>> to be at least 16 bits.
>>
>> Ensured maybe by the C standard but we use u32 and 'unsigned int'
>> interchangably everywhere. There are some inferior architectures that
>> use different type witdths, but all we care is 32bit and 64bit.
>
> Personally speaking, that's not a good practice at all.
>
> You'll never know when you'll hit a new arch.
>
> One best example here is subpage testing. I believe you're also
> utilizing arch64 to do the test, and thankfully it has all the same
> widths here, but you can never be that sure.
>
A lot of the kernel is coded with the assumption that int is at least 32
bits if it wasn't things a lot of things would break.
>>
>>> But for incoming subpage support, we are going to introduce more bits,
>>> thus we will go beyond 16 bits.
>>>
>>> To support this, make extent_state::state at least 32bit and to be more
>>> explicit, we use "u32" to be clear about the max supported bits.
>>
>> Yeah that's fine to make the expected width requirement explicit.
>>
>
> As long as this can be merged, I'm completely fine though.
>
> Thanks,
> Qu
>
next prev parent reply other threads:[~2020-11-19 7:18 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 12:51 [PATCH v2 00/24] btrfs: preparation patches for subpage support Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 01/24] btrfs: tests: fix free space tree test failure on 64K page system Qu Wenruo
2020-11-17 11:53 ` Nikolay Borisov
2020-11-13 12:51 ` [PATCH v2 02/24] btrfs: extent-io-tests: remove invalid tests Qu Wenruo
2020-11-13 18:42 ` Josef Bacik
2020-11-19 21:08 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 03/24] btrfs: extent_io: replace extent_start/extent_len with better structure for end_bio_extent_readpage() Qu Wenruo
2020-11-13 19:13 ` Josef Bacik
2020-11-18 16:05 ` David Sterba
2020-11-18 23:49 ` Qu Wenruo
2020-11-19 20:30 ` David Sterba
2020-11-19 21:08 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 04/24] btrfs: extent_io: introduce helper to handle page status update in end_bio_extent_readpage() Qu Wenruo
2020-11-13 19:18 ` Josef Bacik
2020-11-18 20:27 ` David Sterba
2020-11-18 23:43 ` Qu Wenruo
2020-11-19 18:32 ` David Sterba
2020-11-19 21:08 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 05/24] btrfs: extent_io: extract the btree page submission code into its own helper function Qu Wenruo
2020-11-13 19:22 ` Josef Bacik
2020-11-18 20:04 ` David Sterba
2020-11-18 20:09 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 06/24] btrfs: remove the phy_offset parameter for btrfs_validate_metadata_buffer() Qu Wenruo
2020-11-19 21:09 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 07/24] btrfs: pass bio_offset to check_data_csum() directly Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 08/24] btrfs: inode: make btrfs_verify_data_csum() follow sector size Qu Wenruo
2020-11-13 19:43 ` Josef Bacik
2020-11-13 12:51 ` [PATCH v2 09/24] btrfs: extent_io: calculate inline extent buffer page size based on page size Qu Wenruo
2020-11-13 19:47 ` Josef Bacik
2020-11-14 0:11 ` Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 10/24] btrfs: introduce a helper to determine if the sectorsize is smaller than PAGE_SIZE Qu Wenruo
2020-11-16 22:51 ` David Sterba
2020-11-16 23:50 ` Qu Wenruo
2020-11-17 0:24 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 11/24] btrfs: extent_io: don't allow tree block to cross page boundary for subpage support Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 12/24] btrfs: extent_io: update num_extent_pages() to support subpage sized extent buffer Qu Wenruo
2020-11-18 16:22 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 13/24] btrfs: handle sectorsize < PAGE_SIZE case for extent buffer accessors Qu Wenruo
2020-11-18 19:30 ` David Sterba
2020-11-18 19:38 ` David Sterba
2020-11-18 19:48 ` David Sterba
2020-11-24 6:20 ` Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 14/24] btrfs: disk-io: only clear EXTENT_LOCK bit for extent_invalidatepage() Qu Wenruo
2020-11-19 21:09 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 15/24] btrfs: extent-io: make type of extent_state::state to be at least 32 bits Qu Wenruo
2020-11-13 18:40 ` Josef Bacik
2020-11-18 16:11 ` David Sterba
2020-11-18 23:48 ` Qu Wenruo
2020-11-19 7:18 ` Nikolay Borisov [this message]
2020-11-19 21:09 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 16/24] btrfs: file-item: use nodesize to determine whether we need readahead for btrfs_lookup_bio_sums() Qu Wenruo
2020-11-19 21:09 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 17/24] btrfs: file-item: remove the btrfs_find_ordered_sum() call in btrfs_lookup_bio_sums() Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 18/24] btrfs: file-item: refactor btrfs_lookup_bio_sums() to handle out-of-order bvecs Qu Wenruo
2020-11-18 16:27 ` David Sterba
2020-11-18 23:57 ` Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 19/24] btrfs: scrub: remove the anonymous structure from scrub_page Qu Wenruo
2020-11-18 19:00 ` David Sterba
2020-11-19 21:09 ` David Sterba
2020-11-13 12:51 ` [PATCH v2 20/24] btrfs: scrub: always allocate one full page for one sector for RAID56 Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 21/24] btrfs: scrub: support subpage tree block scrub Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 22/24] btrfs: scrub: support subpage data scrub Qu Wenruo
2020-11-18 16:29 ` David Sterba
2020-11-18 23:38 ` Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 23/24] btrfs: scrub: allow scrub to work with subpage sectorsize Qu Wenruo
2020-11-13 12:51 ` [PATCH v2 24/24] btrfs: extent_io: Use detach_page_private() for alloc_extent_buffer() Qu Wenruo
2020-11-13 20:05 ` [PATCH v2 00/24] btrfs: preparation patches for subpage support Josef Bacik
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