On 2021/6/10 下午1:23, 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 <l...@intel.com>
Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
  fs/btrfs/Kconfig | 2 ++
  1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 68b95ad82126..520a0f6a7d9e 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -18,6 +18,8 @@ config BTRFS_FS
        select RAID6_PQ
        select XOR_BLOCKS
        select SRCU
+       depends on !PPC_256K_PAGES      # powerpc
+       depends on !PAGE_SIZE_256KB     # hexagon

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,

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