From: "Brian Cain" <bcain@codeaurora.org>
To: "'Christophe Leroy'" <christophe.leroy@csgroup.eu>,
"'Chris Mason'" <clm@fb.com>
Cc: "'Josef Bacik'" <josef@toxicpanda.com>,
"'David Sterba'" <dsterba@suse.com>,
<linux-kernel@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org>,
"'linux-btrfs'" <linux-btrfs@vger.kernel.org>,
<linux-hexagon@vger.kernel.org>
Subject: RE: [PATCH] btrfs: Disable BTRFS on platforms having 256K pages
Date: Sat, 12 Jun 2021 09:44:05 -0500 [thread overview]
Message-ID: <17a401d75f99$662cdc50$328694f0$@codeaurora.org> (raw)
In-Reply-To: <cdadf66e-0a6e-4efe-0326-7236c43b2735@csgroup.eu>
> -----Original Message-----
> From: Christophe Leroy <christophe.leroy@csgroup.eu>
...
> Le 10/06/2021 à 15:54, Chris Mason a écrit :
> >
> >> On Jun 10, 2021, at 1:23 AM, Christophe Leroy
> <christophe.leroy@csgroup.eu> wrote:
> >>
> >> With a config having PAGE_SIZE set to 256K, BTRFS build fails
> >> with the following message
> >>
> >> include/linux/compiler_types.h:326:38: error: call to
> '__compiletime_assert_791' declared with attribute error: BUILD_BUG_ON
> failed: (BTRFS_MAX_COMPRESSED % PAGE_SIZE) != 0
> >>
> >> BTRFS_MAX_COMPRESSED being 128K, BTRFS cannot support platforms
> with
> >> 256K pages at the time being.
> >>
> >> There are two platforms that can select 256K pages:
> >> - hexagon
> >> - powerpc
> >>
> >> Disable BTRFS when 256K page size is selected.
> >>
> >
> > We’ll have other subpage blocksize concerns with 256K pages, but this
> BTRFS_MAX_COMPRESSED #define is arbitrary. It’s just trying to have an
> upper bound on the amount of memory we’ll need to uncompress a single
> page’s worth of random reads.
> >
> > We could change it to max(PAGE_SIZE, 128K) or just bump to 256K.
> >
>
> But if 256K is problematic in other ways, is it worth bumping
> BTRFS_MAX_COMPRESSED to 256K ?
>
> David, in below mail, said that 256K support would require deaper changes. So
> disabling BTRFS
> support seems the easiest solution for the time being, at least for Stable (I
> forgot the Fixes: tag
> and the CC: to stable).
>
> On powerpc, 256k pages is a corner case, it requires customised binutils, so I
> don't think disabling
> BTRFS is a issue there. For hexagon I don't know.
Larger page sizes like this are typical for hexagon. Disabling btrfs on hexagon seems appropriate.
-Brian
WARNING: multiple messages have this Message-ID (diff)
From: "Brian Cain" <bcain@codeaurora.org>
To: "'Christophe Leroy'" <christophe.leroy@csgroup.eu>,
"'Chris Mason'" <clm@fb.com>
Cc: linux-hexagon@vger.kernel.org,
'Josef Bacik' <josef@toxicpanda.com>,
linux-kernel@vger.kernel.org, 'David Sterba' <dsterba@suse.com>,
linuxppc-dev@lists.ozlabs.org,
'linux-btrfs' <linux-btrfs@vger.kernel.org>
Subject: RE: [PATCH] btrfs: Disable BTRFS on platforms having 256K pages
Date: Sat, 12 Jun 2021 09:44:05 -0500 [thread overview]
Message-ID: <17a401d75f99$662cdc50$328694f0$@codeaurora.org> (raw)
In-Reply-To: <cdadf66e-0a6e-4efe-0326-7236c43b2735@csgroup.eu>
> -----Original Message-----
> From: Christophe Leroy <christophe.leroy@csgroup.eu>
...
> Le 10/06/2021 à 15:54, Chris Mason a écrit :
> >
> >> On Jun 10, 2021, at 1:23 AM, Christophe Leroy
> <christophe.leroy@csgroup.eu> wrote:
> >>
> >> With a config having PAGE_SIZE set to 256K, BTRFS build fails
> >> with the following message
> >>
> >> include/linux/compiler_types.h:326:38: error: call to
> '__compiletime_assert_791' declared with attribute error: BUILD_BUG_ON
> failed: (BTRFS_MAX_COMPRESSED % PAGE_SIZE) != 0
> >>
> >> BTRFS_MAX_COMPRESSED being 128K, BTRFS cannot support platforms
> with
> >> 256K pages at the time being.
> >>
> >> There are two platforms that can select 256K pages:
> >> - hexagon
> >> - powerpc
> >>
> >> Disable BTRFS when 256K page size is selected.
> >>
> >
> > We’ll have other subpage blocksize concerns with 256K pages, but this
> BTRFS_MAX_COMPRESSED #define is arbitrary. It’s just trying to have an
> upper bound on the amount of memory we’ll need to uncompress a single
> page’s worth of random reads.
> >
> > We could change it to max(PAGE_SIZE, 128K) or just bump to 256K.
> >
>
> But if 256K is problematic in other ways, is it worth bumping
> BTRFS_MAX_COMPRESSED to 256K ?
>
> David, in below mail, said that 256K support would require deaper changes. So
> disabling BTRFS
> support seems the easiest solution for the time being, at least for Stable (I
> forgot the Fixes: tag
> and the CC: to stable).
>
> On powerpc, 256k pages is a corner case, it requires customised binutils, so I
> don't think disabling
> BTRFS is a issue there. For hexagon I don't know.
Larger page sizes like this are typical for hexagon. Disabling btrfs on hexagon seems appropriate.
-Brian
next prev parent reply other threads:[~2021-06-12 14:44 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 5:23 [PATCH] fs: btrfs: Disable BTRFS on platforms having 256K pages Christophe Leroy
2021-06-10 5:23 ` Christophe Leroy
2021-06-10 13:54 ` [PATCH] " Chris Mason
2021-06-10 13:54 ` Chris Mason
2021-06-10 14:50 ` Christophe Leroy
2021-06-10 14:50 ` Christophe Leroy
2021-06-10 16:20 ` David Sterba
2021-06-10 16:20 ` David Sterba
2021-06-11 12:58 ` Chris Mason
2021-06-11 12:58 ` Chris Mason
2021-06-11 13:21 ` David Sterba
2021-06-11 13:21 ` David Sterba
2021-06-11 16:56 ` Chris Mason
2021-06-11 16:56 ` Chris Mason
2021-06-12 14:44 ` Brian Cain [this message]
2021-06-12 14:44 ` Brian Cain
2021-06-11 12:34 ` [PATCH] fs: " David Sterba
2021-06-11 12:34 ` David Sterba
2021-06-11 13:47 ` Qu Wenruo
2021-06-11 13:47 ` Qu Wenruo
2022-01-04 23:32 ` Qu Wenruo
2022-01-04 23:32 ` Qu Wenruo
2022-01-06 16:31 ` Neal Gompa
2022-01-06 16:31 ` Neal Gompa
2022-01-07 0:13 ` Qu Wenruo
2022-01-07 0:13 ` Qu Wenruo
2022-01-07 2:45 ` Hector Martin
2022-01-07 2:45 ` Hector Martin
2022-01-07 4:55 ` Michael Ellerman
2022-01-07 4:55 ` Michael Ellerman
2022-01-07 5:21 ` Qu Wenruo
2022-01-07 5:21 ` Qu Wenruo
2022-01-10 8:29 ` Christophe Leroy
2022-01-10 8:29 ` Christophe Leroy
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