From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: dsterba@suse.cz, Neal Gompa <ngompa13@gmail.com>,
Qu Wenruo <wqu@suse.com>,
Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH v6 00/15] btrfs: add data write support for subpage
Date: Thu, 8 Jul 2021 13:27:00 +0200 [thread overview]
Message-ID: <20210708112700.GW2610@twin.jikos.cz> (raw)
In-Reply-To: <843d839c-11f5-40e3-9871-e462254113b1@gmx.com>
On Thu, Jul 08, 2021 at 07:19:28AM +0800, Qu Wenruo wrote:
>
>
> On 2021/7/8 上午2:14, David Sterba wrote:
> > On Wed, Jul 07, 2021 at 01:41:46PM -0400, Neal Gompa wrote:
> >>> But on the other hand, I'm not sure what's the proper way to introduce a
> >>> fix for v5.15 window.
> >>>
> >>> Should I just disable readahead for compression read (which just needs
> >>> two lines to return 0 for subpage case in add_ra_bio_pages())?
> >>>
> >>> Or should I add the proper fix into the patchset?
> >>
> >> If this is going into 5.15 instead of 5.14, just add the proper fix
> >> into this patch set. But if we want to land this in 5.14, I would
> >> suggest disabling it for now and then having a separate patch set for
> >> that.
> >
> > 5.14 is not possible, there are other subpage changes already merged so
> > fixes to existing level of support (still limited) can go to 5.14-rcs
> > but this whole patchses it is targeting 5.15.
> >
> >> You're already targeting 5.15 (though I kind of want this in 5.14...),
> >> so I suggest going with adding the fix to the patch set.
> >
> > For 5.15 it's free to do any change, eg. fold the fix or do a separate
> > patch explaining all the details.
>
> Another reason why I'm considering to disable that readahead ability is,
> it really makes little sense for 64K page size.
>
> Our maximum compressed extent size is just 128K, at most 3 pages for 64K
> page size (that's when the extent is not page aligned).
>
> Just saving two reads (which may only be one or 2 4K sectors) doesn't
> really make it worthy, especially considering the change to ra itself is
> going to affecting common code path.
>
> Thus I prefer to disable for the initial support, and only add the
> proper fix for the compression write support.
Ok.
> > In general the development changes must be ready at the rc5 time at the
> > latest (with a week or two for some testing and catching last bugs).
> > Once it's due there's like two months until the next code freeze.
> >
>
> Great, I'll just add a simple disabling patch with comments on why the
> current code doesn't work and why it's fine to disable it for 64K page size.
Yes please, there's a number of things that won't be initially
implemented so we need to keep track (changelogs and/or comments).
prev parent reply other threads:[~2021-07-08 11:29 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-05 2:00 [PATCH v6 00/15] btrfs: add data write support for subpage Qu Wenruo
2021-07-05 2:00 ` [PATCH v6 01/15] btrfs: grab correct extent map for subpage compressed extent read Qu Wenruo
2021-07-08 6:50 ` Anand Jain
2021-07-08 7:06 ` Qu Wenruo
2021-07-09 9:13 ` Anand Jain
2021-07-05 2:00 ` [PATCH v6 02/15] btrfs: remove the GFP_HIGHMEM flag for compression code Qu Wenruo
2021-07-08 11:54 ` David Sterba
2021-07-08 12:11 ` Qu Wenruo
2021-07-05 2:00 ` [PATCH v6 03/15] btrfs: rework btrfs_decompress_buf2page() Qu Wenruo
2021-07-09 18:53 ` David Sterba
2021-07-09 22:03 ` Qu Wenruo
2021-07-09 19:26 ` David Sterba
2021-07-05 2:00 ` [PATCH v6 04/15] btrfs: rework lzo_decompress_bio() to make it subpage compatible Qu Wenruo
2021-07-09 20:37 ` David Sterba
2021-07-05 2:01 ` [PATCH v6 05/15] btrfs: extract relocation page read and dirty part into its own function Qu Wenruo
2021-07-05 2:01 ` [PATCH v6 06/15] btrfs: make relocate_one_page() to handle subpage case Qu Wenruo
2021-07-05 2:01 ` [PATCH v6 07/15] btrfs: fix wild subpage writeback which does not have ordered extent Qu Wenruo
2021-07-05 2:01 ` [PATCH v6 08/15] btrfs: disable inline extent creation for subpage Qu Wenruo
2021-07-05 2:01 ` [PATCH v6 09/15] btrfs: allow submit_extent_page() to do bio split " Qu Wenruo
2021-07-05 2:01 ` [PATCH v6 10/15] btrfs: reject raid5/6 fs " Qu Wenruo
2021-07-09 9:36 ` Anand Jain
2021-07-09 18:34 ` David Sterba
2021-07-05 2:01 ` [PATCH v6 11/15] btrfs: fix a crash caused by race between prepare_pages() and btrfs_releasepage() Qu Wenruo
2021-07-05 2:01 ` [PATCH v6 12/15] btrfs: fix a use-after-free bug in writeback subpage helper Qu Wenruo
2021-07-05 2:01 ` [PATCH v6 13/15] btrfs: fix a subpage false alert for relocating partial preallocated data extents Qu Wenruo
2021-07-05 2:01 ` [PATCH v6 14/15] btrfs: fix a subpage relocation data corruption Qu Wenruo
2021-07-05 2:01 ` [PATCH v6 15/15] btrfs: allow read-write for 4K sectorsize on 64K page size systems Qu Wenruo
2021-07-07 8:28 ` [PATCH v6 00/15] btrfs: add data write support for subpage Qu Wenruo
2021-07-07 17:41 ` Neal Gompa
2021-07-07 18:14 ` David Sterba
2021-07-07 23:19 ` Qu Wenruo
2021-07-08 11:27 ` David Sterba [this message]
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