Hi Qu,

Le 05/01/2022 à 00:32, Qu Wenruo a écrit :

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

https://github.com/adam900710/linux/tree/metadata_subpage_switch

Thanks,
Qu

On 2021/6/10 13:23, Christophe Leroy wrote:

quoted

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(+)

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

      help
        Btrfs is a general purpose copy-on-write filesystem with extents,