From: Nikolay Borisov <nborisov@suse.com>
To: Qu Wenruo <wqu@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 05/17] btrfs: don't allow tree block to cross page boundary for subpage support
Date: Fri, 11 Sep 2020 15:08:08 +0300 [thread overview]
Message-ID: <937dacc6-77d9-223d-87e3-d67adbcc9036@suse.com> (raw)
In-Reply-To: <bbd266f4-c329-c15c-37c6-5ef768ad8e25@suse.com>
On 11.09.20 г. 14:36 ч., Qu Wenruo wrote:
>
>
> On 2020/9/11 下午6:26, Nikolay Borisov wrote:
>>
>>
>> On 8.09.20 г. 10:52 ч., Qu Wenruo wrote:
>>> As a preparation for subpage sector size support (allow sector size
>>> smaller than page size to be mounted), if the sector size is smaller
>>
>> nit: (allowing filesystem with sector size smaller than page size to be
>> mounted)
>>
>>> than page size, we don't allow tree block to be read if it cross page
>>> boundary (normally 64K).
>>
>> Why normally 64k ?
>
> Because there are only two major arches supporting non-4k page size,
> ppc64 which uses 64K page size, and arm which can support 4K, 16K and
> 64K page size.
>
> Currently our plan is only to support 64K page size and 4K page size.
I really rather make the support generic rather than boxing ourselves in
some "artificial" constraints.
>
> Furthermore, that 64K magic number matches with 64K stripe length of
> btrfs, thus we choose 64K as the boundary.
>
>> I suspect you assume readers are familiar with the
>> motivation for this work which they don't necessarily need to be. Please
>> make your sentences explicit. Correct me if I'm wrong but you are
>> ensuring that an eb doesn't cross the largest possible sectorsize?
>
> That's correct, and by incident, it's also the stripe length of btrfs
> RAID, and scrub stripe length too.
>
> (And scrub can't handle such tree block either)
And that by itself is a good reason why we may want to support just 64k.
So state that explicitly.
>
> Thanks,
> Qu
>
<snip>
next prev parent reply other threads:[~2020-09-11 12:08 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-08 7:52 [PATCH 00/17] btrfs: add read-only support for subpage sector size Qu Wenruo
2020-09-08 7:52 ` [PATCH 01/17] btrfs: extent-io-tests: remove invalid tests Qu Wenruo
2020-09-09 12:26 ` Nikolay Borisov
2020-09-09 13:06 ` Qu Wenruo
2020-09-08 7:52 ` [PATCH 02/17] btrfs: calculate inline extent buffer page size based on page size Qu Wenruo
2020-09-11 9:56 ` Nikolay Borisov
2020-09-11 10:13 ` Qu Wenruo
2020-09-08 7:52 ` [PATCH 03/17] btrfs: remove the open-code to read disk-key Qu Wenruo
2020-09-11 10:07 ` Nikolay Borisov
2020-09-08 7:52 ` [PATCH 04/17] btrfs: make btrfs_fs_info::buffer_radix to take sector size devided values Qu Wenruo
2020-09-11 10:11 ` Nikolay Borisov
2020-09-11 10:15 ` Qu Wenruo
2020-09-08 7:52 ` [PATCH 05/17] btrfs: don't allow tree block to cross page boundary for subpage support Qu Wenruo
2020-09-11 10:26 ` Nikolay Borisov
2020-09-11 11:36 ` Qu Wenruo
2020-09-11 12:08 ` Nikolay Borisov [this message]
2020-09-08 7:52 ` [PATCH 06/17] btrfs: handle sectorsize < PAGE_SIZE case for extent buffer accessors Qu Wenruo
2020-09-08 7:52 ` [PATCH 07/17] btrfs: make csum_tree_block() handle sectorsize smaller than page size Qu Wenruo
2020-09-11 11:10 ` Nikolay Borisov
2020-09-08 7:52 ` [PATCH 08/17] btrfs: refactor how we extract extent buffer from page for alloc_extent_buffer() Qu Wenruo
2020-09-11 11:14 ` Nikolay Borisov
2020-09-08 7:52 ` [PATCH 09/17] btrfs: refactor btrfs_release_extent_buffer_pages() Qu Wenruo
2020-09-11 11:17 ` Nikolay Borisov
2020-09-11 11:39 ` Qu Wenruo
2020-09-08 7:52 ` [PATCH 10/17] btrfs: add assert_spin_locked() for attach_extent_buffer_page() Qu Wenruo
2020-09-11 11:22 ` Nikolay Borisov
2020-09-08 7:52 ` [PATCH 11/17] btrfs: extract the extent buffer verification from btree_readpage_end_io_hook() Qu Wenruo
2020-09-11 13:00 ` Nikolay Borisov
2020-09-08 7:52 ` [PATCH 12/17] btrfs: remove the unnecessary parameter @start and @len for check_data_csum() Qu Wenruo
2020-09-11 13:50 ` Nikolay Borisov
2020-09-08 7:52 ` [PATCH 13/17] btrfs: extent_io: only require sector size alignment for page read Qu Wenruo
2020-09-11 13:55 ` Nikolay Borisov
2020-09-15 1:54 ` Qu Wenruo
2020-09-08 7:52 ` [PATCH 14/17] btrfs: make btrfs_readpage_end_io_hook() follow sector size Qu Wenruo
2020-09-09 17:34 ` Goldwyn Rodrigues
2020-09-10 0:05 ` Qu Wenruo
2020-09-10 14:26 ` Goldwyn Rodrigues
2020-09-08 7:52 ` [PATCH 15/17] btrfs: introduce subpage_eb_mapping for extent buffers Qu Wenruo
2020-09-08 10:22 ` kernel test robot
2020-09-08 14:24 ` Dan Carpenter
2020-09-08 7:52 ` [PATCH 16/17] btrfs: handle extent buffer verification proper for subpage size Qu Wenruo
2020-09-08 7:52 ` [PATCH 17/17] btrfs: allow RO mount of 4K sector size fs on 64K page system Qu Wenruo
2020-09-08 8:03 ` [PATCH 00/17] btrfs: add read-only support for subpage sector size Qu Wenruo
2020-09-11 10:24 ` Qu Wenruo
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