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From: Qu Wenruo <quwenruo.btrfs@gmx.com>
To: Neal Gompa <ngompa13@gmail.com>, Qu Wenruo <wqu@suse.com>
Cc: Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
	Josef Bacik <josef@toxicpanda.com>,
	Chris Murphy <lists@colorremedies.com>
Subject: Re: [PATCH v2 00/19] btrfs: add read-only support for subpage sector size
Date: Thu, 17 Sep 2020 08:24:16 +0800	[thread overview]
Message-ID: <a50bcca5-3704-c7f3-6358-5015d797adf6@gmx.com> (raw)
In-Reply-To: <CAEg-Je-204GbuVRyrAK+jSYN9YPpCJf8e7CneyYz+PtRxbM1EQ@mail.gmail.com>


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On 2020/9/17 上午8:13, Neal Gompa wrote:
> On Wed, Sep 16, 2020 at 8:03 PM Qu Wenruo <wqu@suse.com> wrote:
>>
>>
>>
>> On 2020/9/17 上午12:18, Neal Gompa wrote:
>>> On Tue, Sep 15, 2020 at 1:36 AM Qu Wenruo <wqu@suse.com> wrote:
>>>>
>>>> Patches can be fetched from github:
>>>> https://github.com/adam900710/linux/tree/subpage
>>>>
>>>> Currently btrfs only allows to mount fs with sectorsize == PAGE_SIZE.
>>>>
>>>> That means, for 64K page size system, they can only use 64K sector size
>>>> fs.
>>>> This brings a big compatible problem for btrfs.
>>>>
>>>> This patch is going to slightly solve the problem by, allowing 64K
>>>> system to mount 4K sectorsize fs in read-only mode.
>>>>
>>>> The main objective here, is to remove the blockage in the code base, and
>>>> pave the road to full RW mount support.
>>>>
>>>
>>> Is there a reason we don't include a patch in here to just hardwire
>>> the block size to 4K going forward?
>>>
>>
>> Did you mean to make 4K sector size the hard requirement?
>>
>> That would make existing 64K sector size fs unable to be mounted then.
>>
> 
> I mean, make the 64K variant a legacy one and force 4K for all new
> filesystems. That then simplifies this work to making it mountable and
> usable as a legacy filesystem format.

That's the plan.

But not for now, since currently the subpage support is only read-only.

> 
> I guess that would be an incompat flag, no?

No need for incompat flag.

For older kernel they just can't mount subpage fs.

Thanks,
Qu

> 
> 
> 
> --
> 真実はいつも一つ！/ Always, there's only one truth!
> 


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      reply	other threads:[~2020-09-17  0:29 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15  5:35 [PATCH v2 00/19] btrfs: add read-only support for subpage sector size Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 01/19] btrfs: extent-io-tests: remove invalid tests Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 02/19] btrfs: remove the unnecessary parameter @start and @len for check_data_csum() Qu Wenruo
2020-09-15  8:39   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 03/19] btrfs: calculate inline extent buffer page size based on page size Qu Wenruo
2020-09-15  8:35   ` Nikolay Borisov
2020-09-15 10:05     ` Qu Wenruo
2020-09-15  8:40   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 04/19] btrfs: remove the open-code to read disk-key Qu Wenruo
2020-09-15  8:36   ` Nikolay Borisov
2020-09-15  8:40   ` Johannes Thumshirn
2020-09-16 16:01   ` David Sterba
2020-09-17  8:02     ` Qu Wenruo
2020-09-17 12:37       ` David Sterba
2020-09-17 13:15         ` Qu Wenruo
2020-09-17 22:41           ` David Sterba
2020-09-17 23:26             ` Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 05/19] btrfs: make btrfs_fs_info::buffer_radix to take sector size devided values Qu Wenruo
2020-09-15  8:27   ` Johannes Thumshirn
2020-09-15 10:04     ` Qu Wenruo
2020-09-15 10:12       ` Johannes Thumshirn
2020-09-15 17:40   ` kernel test robot
2020-09-15  5:35 ` [PATCH v2 06/19] btrfs: don't allow tree block to cross page boundary for subpage support Qu Wenruo
2020-09-15  8:37   ` Nikolay Borisov
2020-09-15 10:06     ` Qu Wenruo
2020-09-15  8:44   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 07/19] btrfs: update num_extent_pages() to support subpage sized extent buffer Qu Wenruo
2020-09-15  8:42   ` Johannes Thumshirn
2020-09-15 10:07     ` Qu Wenruo
2020-09-15 10:12       ` Johannes Thumshirn
2020-09-15 10:07     ` Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 08/19] btrfs: handle sectorsize < PAGE_SIZE case for extent buffer accessors Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 09/19] btrfs: make csum_tree_block() handle sectorsize smaller than page size Qu Wenruo
2020-09-15  8:47   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 10/19] btrfs: add assert_spin_locked() for attach_extent_buffer_page() Qu Wenruo
2020-09-15  8:52   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 11/19] btrfs: extract the extent buffer verification from btree_readpage_end_io_hook() Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 12/19] btrfs: extent_io: only require sector size alignment for page read Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 13/19] btrfs: make btrfs_readpage_end_io_hook() follow sector size Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 14/19] btrfs: make btree inode io_tree has its special owner Qu Wenruo
2020-09-16  9:28   ` Johannes Thumshirn
2020-09-16 16:06   ` David Sterba
2020-09-17  0:02     ` Qu Wenruo
2020-09-17 12:50       ` David Sterba
2020-09-18  8:18         ` Qu Wenruo
2020-09-22 14:06           ` David Sterba
2020-09-22 14:14   ` David Sterba
2020-09-15  5:35 ` [PATCH v2 15/19] btrfs: don't set extent_io_tree bits for btree inode at endio time Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 16/19] btrfs: use extent_io_tree to handle subpage extent buffer allocation Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 17/19] btrfs: implement subpage metadata read and its endio function Qu Wenruo
2020-09-16  8:47   ` kernel test robot
2020-09-15  5:35 ` [PATCH v2 18/19] btrfs: implement btree_readpage() and try_release_extent_buffer() for subpage Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 19/19] btrfs: allow RO mount of 4K sector size fs on 64K page system Qu Wenruo
2020-09-16  1:35 ` [PATCH v2 00/19] btrfs: add read-only support for subpage sector size Qu Wenruo
2020-09-16 16:18 ` Neal Gompa
2020-09-17  0:03   ` Qu Wenruo
2020-09-17  0:13     ` Neal Gompa
2020-09-17  0:24       ` Qu Wenruo [this message]

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