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.
Reported-by: kernel test robot <redacted>
Signed-off-by: Christophe Leroy <redacted>
---
fs/btrfs/Kconfig | 2 ++
1 file changed, 2 insertions(+)
From: Chris Mason <hidden> Date: 2021-06-10 13:54:46
On Jun 10, 2021, at 1:23 AM, Christophe Leroy [off-list ref] 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.
-chris
On Jun 10, 2021, at 1:23 AM, Christophe Leroy [off-list ref] 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.
https://lkml.org/lkml/2021/6/9/978
Le 09/06/2021 à 17:22, David Sterba a écrit :
On Wed, Jun 09, 2021 at 04:01:20PM +0200, Christophe Leroy wrote:
quoted
Le 09/06/2021 à 15:55, kernel test robot a écrit :
That's a BTRFS issue, and not directly linked to the above mentioned commit. Before that commit the
problem was already present.
Problem is that with 256k PAGE_SIZE, following BUILD_BUG() pops up:
BUILD_BUG_ON((BTRFS_MAX_COMPRESSED % PAGE_SIZE) != 0)
A 256K page is a problem for btrfs, until now I was not even aware
there's an architecture supporting that so. That the build fails is
probably best thing. Maximum metadata nodesize supported is 64K and
having that on a 256K page would need deeper changes, no top of the
currently developed subpage changes (that do 4K blocks on 64K pages).
From: David Sterba <hidden> Date: 2021-06-10 16:23:38
On Thu, Jun 10, 2021 at 04:50:09PM +0200, Christophe Leroy wrote:
Le 10/06/2021 à 15:54, Chris Mason a écrit :
quoted
quoted
On Jun 10, 2021, at 1:23 AM, Christophe Leroy [off-list ref] 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.
That it blew up due to the max compressed size is a coincidence. We
could have explicit BUILD_BUG_ONs for page size or other constraints
derived from the page size like INLINE_EXTENT_BUFFER_PAGES.
And there's no such thing like "just bump BTRFS_MAX_COMPRESSED to 256K".
The constant is part of on-disk format for lzo and otherwise changing it
would impact performance so this would need proper evaluation.
From: David Sterba <hidden> Date: 2021-06-11 12:36:52
On Thu, Jun 10, 2021 at 05:23:02AM +0000, Christophe Leroy 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.
Reported-by: kernel test robot <redacted>
Signed-off-by: Christophe Leroy <redacted>
With updated changelog added to misc-next, thanks.
From: Chris Mason <hidden> Date: 2021-06-11 12:59:25
On Jun 10, 2021, at 12:20 PM, David Sterba [off-list ref] wrote:
On Thu, Jun 10, 2021 at 04:50:09PM +0200, Christophe Leroy wrote:
quoted
Le 10/06/2021 à 15:54, Chris Mason a écrit :
quoted
quoted
On Jun 10, 2021, at 1:23 AM, Christophe Leroy [off-list ref] 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.
That it blew up due to the max compressed size is a coincidence. We
could have explicit BUILD_BUG_ONs for page size or other constraints
derived from the page size like INLINE_EXTENT_BUFFER_PAGES.
Right, the constraint is bigger and more complex than BTRFS_MAX_COMPRESSED.
And there's no such thing like "just bump BTRFS_MAX_COMPRESSED to 256K".
The constant is part of on-disk format for lzo and otherwise changing it
would impact performance so this would need proper evaluation.
Sorry, how is it baked into LZO? It definitely will have performance implications, I agree there.
-chris
From: David Sterba <hidden> Date: 2021-06-11 13:24:11
On Fri, Jun 11, 2021 at 12:58:58PM +0000, Chris Mason wrote:
quoted
On Jun 10, 2021, at 12:20 PM, David Sterba [off-list ref] wrote:
On Thu, Jun 10, 2021 at 04:50:09PM +0200, Christophe Leroy wrote:
quoted
Le 10/06/2021 à 15:54, Chris Mason a écrit :
quoted
quoted
On Jun 10, 2021, at 1:23 AM, Christophe Leroy [off-list ref] wrote:
And there's no such thing like "just bump BTRFS_MAX_COMPRESSED to 256K".
The constant is part of on-disk format for lzo and otherwise changing it
would impact performance so this would need proper evaluation.
Sorry, how is it baked into LZO? It definitely will have performance implications, I agree there.
lzo_decompress_bio:
309 /*
310 * Compressed data header check.
311 *
312 * The real compressed size can't exceed the maximum extent length, and
313 * all pages should be used (whole unused page with just the segment
314 * header is not possible). If this happens it means the compressed
315 * extent is corrupted.
316 */
317 if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
318 tot_len < srclen - PAGE_SIZE) {
319 ret = -EUCLEAN;
320 goto done;
321 }
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.
Reported-by: kernel test robot <redacted>
Signed-off-by: Christophe Leroy <redacted>
---
fs/btrfs/Kconfig | 2 ++
1 file changed, 2 insertions(+)
I'm OK to disable page size other than 4K, 16K, 32K, 64K for now.
Although for other reasons.
Not only for the BUILD_BUG_ON(), but for the fact that btrfs only
support 4K, 16K, 32K, 64K sectorsize, and requires PAGE_SIZE == sectorsize.
Although we're adding subpage support, the subpage support only comes
with 4K sectorsize on 64K page size.
Until variable length version is introduced, 256K/128K page size won't
be support.
Thus I'm fine to disable BTRFS for any arch outside of the supported
page sizes for now.
Thanks,
Qu
help
Btrfs is a general purpose copy-on-write filesystem with extents,
From: Chris Mason <hidden> Date: 2021-06-11 16:56:54
On Jun 11, 2021, at 9:21 AM, David Sterba [off-list ref] wrote:
On Fri, Jun 11, 2021 at 12:58:58PM +0000, Chris Mason wrote:
quoted
quoted
On Jun 10, 2021, at 12:20 PM, David Sterba [off-list ref] wrote:
On Thu, Jun 10, 2021 at 04:50:09PM +0200, Christophe Leroy wrote:
quoted
Le 10/06/2021 à 15:54, Chris Mason a écrit :
quoted
quoted
On Jun 10, 2021, at 1:23 AM, Christophe Leroy [off-list ref] wrote:
And there's no such thing like "just bump BTRFS_MAX_COMPRESSED to 256K".
The constant is part of on-disk format for lzo and otherwise changing it
would impact performance so this would need proper evaluation.
Sorry, how is it baked into LZO? It definitely will have performance implications, I agree there.
lzo_decompress_bio:
309 /*
310 * Compressed data header check.
311 *
312 * The real compressed size can't exceed the maximum extent length, and
313 * all pages should be used (whole unused page with just the segment
314 * header is not possible). If this happens it means the compressed
315 * extent is corrupted.
316 */
317 if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
318 tot_len < srclen - PAGE_SIZE) {
319 ret = -EUCLEAN;
320 goto done;
321 }
Ah I see, so going back to an old LZO kernel will get upset. Ok, fair enough. So if we want to bump this for other reasons, we’ll need to make an LZO max size to maintain compatibility.
-chris
BTRFS_MAX_COMPRESSED being 128K, BTRFS cannot support platforms
with
quoted
quoted
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.
quoted
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
Hi Christophe,
I'm recently enhancing the subpage support for btrfs, and my current
branch should solve the problem for btrfs to support larger page sizes.
But unfortunately my current test environment can only provide page size
with 64K or 4K, no 16K or 128K/256K support.
Mind to test my new branch on 128K page size systems?
(256K page size support is still lacking though, which will be addressed
in the future)
https://github.com/adam900710/linux/tree/metadata_subpage_switch
Thanks,
Qu
On 2021/6/10 13:23, Christophe Leroy wrote:
quoted hunk
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.
Reported-by: kernel test robot <redacted>
Signed-off-by: Christophe Leroy <redacted>
---
fs/btrfs/Kconfig | 2 ++
1 file changed, 2 insertions(+)
On Wed, Jan 5, 2022 at 7:05 AM Qu Wenruo [off-list ref] wrote:
Hi Christophe,
I'm recently enhancing the subpage support for btrfs, and my current
branch should solve the problem for btrfs to support larger page sizes.
But unfortunately my current test environment can only provide page size
with 64K or 4K, no 16K or 128K/256K support.
Mind to test my new branch on 128K page size systems?
(256K page size support is still lacking though, which will be addressed
in the future)
https://github.com/adam900710/linux/tree/metadata_subpage_switch
The Linux Asahi folks have a 16K page environment (M1 Macs)...
Hector, could you look at it too?
--
真実はいつも一つ！/ Always, there's only one truth!
On Wed, Jan 5, 2022 at 7:05 AM Qu Wenruo [off-list ref] wrote:
quoted
Hi Christophe,
I'm recently enhancing the subpage support for btrfs, and my current
branch should solve the problem for btrfs to support larger page sizes.
But unfortunately my current test environment can only provide page size
with 64K or 4K, no 16K or 128K/256K support.
Mind to test my new branch on 128K page size systems?
(256K page size support is still lacking though, which will be addressed
in the future)
https://github.com/adam900710/linux/tree/metadata_subpage_switch
The Linux Asahi folks have a 16K page environment (M1 Macs)...
Su Yue kindly helped me testing 16K page size, and it's pretty OK there.
So I'm not that concerned.
It's 128K page size that I'm a little concerned, and I have not machine
supporting that large page size to do the test.
Thanks,
Qu
From: Hector Martin <hidden> Date: 2022-01-07 02:45:47
On 2022/01/07 9:13, Qu Wenruo wrote:
On 2022/1/7 00:31, Neal Gompa wrote:
quoted
On Wed, Jan 5, 2022 at 7:05 AM Qu Wenruo [off-list ref] wrote:
quoted
Hi Christophe,
I'm recently enhancing the subpage support for btrfs, and my current
branch should solve the problem for btrfs to support larger page sizes.
But unfortunately my current test environment can only provide page size
with 64K or 4K, no 16K or 128K/256K support.
Mind to test my new branch on 128K page size systems?
(256K page size support is still lacking though, which will be addressed
in the future)
https://github.com/adam900710/linux/tree/metadata_subpage_switch
The Linux Asahi folks have a 16K page environment (M1 Macs)...
Su Yue kindly helped me testing 16K page size, and it's pretty OK there.
So I'm not that concerned.
It's 128K page size that I'm a little concerned, and I have not machine
supporting that large page size to do the test.
Thanks,
Qu
I'm happy to test things on 16K in the future if you need me to :-)
--
Hector Martin (marcan@marcan.st)
Public Key: https://mrcn.st/pub
From: Michael Ellerman <mpe@ellerman.id.au> Date: 2022-01-07 04:56:01
Qu Wenruo [off-list ref] writes:
On 2022/1/7 00:31, Neal Gompa wrote:
quoted
On Wed, Jan 5, 2022 at 7:05 AM Qu Wenruo [off-list ref] wrote:
quoted
Hi Christophe,
I'm recently enhancing the subpage support for btrfs, and my current
branch should solve the problem for btrfs to support larger page sizes.
But unfortunately my current test environment can only provide page size
with 64K or 4K, no 16K or 128K/256K support.
Mind to test my new branch on 128K page size systems?
(256K page size support is still lacking though, which will be addressed
in the future)
https://github.com/adam900710/linux/tree/metadata_subpage_switch
The Linux Asahi folks have a 16K page environment (M1 Macs)...
Su Yue kindly helped me testing 16K page size, and it's pretty OK there.
So I'm not that concerned.
It's 128K page size that I'm a little concerned, and I have not machine
supporting that large page size to do the test.
Did Christophe say he had a 128K system to test on?
In mainline powerpc only supports 4K/16K/64K/256K.
AFAIK there's no arch with 128K page size support, but that's only based
on some grepping, maybe it's hidden somewhere.
cheers
On Wed, Jan 5, 2022 at 7:05 AM Qu Wenruo [off-list ref] wrote:
quoted
Hi Christophe,
I'm recently enhancing the subpage support for btrfs, and my current
branch should solve the problem for btrfs to support larger page sizes.
But unfortunately my current test environment can only provide page size
with 64K or 4K, no 16K or 128K/256K support.
Mind to test my new branch on 128K page size systems?
(256K page size support is still lacking though, which will be addressed
in the future)
https://github.com/adam900710/linux/tree/metadata_subpage_switch
The Linux Asahi folks have a 16K page environment (M1 Macs)...
Su Yue kindly helped me testing 16K page size, and it's pretty OK there.
So I'm not that concerned.
It's 128K page size that I'm a little concerned, and I have not machine
supporting that large page size to do the test.
Did Christophe say he had a 128K system to test on?
In mainline powerpc only supports 4K/16K/64K/256K.
AFAIK there's no arch with 128K page size support, but that's only based
on some grepping, maybe it's hidden somewhere.
My bad, I thought there would be 128K since there is 256K and 64K support, but that's totally wrong.
I'll get PPC guys informed when the 256K page size problem is solved, and then ask for your help.
Thanks,
Qu
Hi Christophe,
I'm recently enhancing the subpage support for btrfs, and my current
branch should solve the problem for btrfs to support larger page sizes.
But unfortunately my current test environment can only provide page size
with 64K or 4K, no 16K or 128K/256K support.
Mind to test my new branch on 128K page size systems?
(256K page size support is still lacking though, which will be addressed
in the future)
I don't have any system with disk, I only use flashdisks with UBIFS
filesystem.
The reason why I did this commit was because of a build failure reported
by Kernel Build Robot, that's it.
Also note that powerpc doesn't have 128K pages. Only 4/16/64/256.
And for 256 it requires a special version of ld and binutils that I
don't have.
I have a board where I can do 16k pages, but again that board has no disk.
Christophe
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.
Reported-by: kernel test robot <redacted>
Signed-off-by: Christophe Leroy <redacted>
---
fs/btrfs/Kconfig | 2 ++
1 file changed, 2 insertions(+)
select RAID6_PQ
select XOR_BLOCKS
select SRCU
+ depends on !PPC_256K_PAGES # powerpc
+ depends on !PAGE_SIZE_256KB # hexagon
help
Btrfs is a general purpose copy-on-write filesystem with extents,