btrfs: allow any block size that is no larger than page size

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Since v5.15 btrfs has support for block size < page size, but we still
only support 4K block size, while there is no special reason that we
cannot support 8K/16K/32K block sizes for 64K page size.

That 4K limit is completely arbitrary, and mostly to reduce test runtime
so we do not need to test all the extra block size combinations.

However that also limits the user choices, some users may understand
what they are doing, and want larger block sizes.  In that case, fixed
4K block size for subpage routine is blocking our way.

Just remove that fixed 4K requirement for block size < page size.

This should not affect regular end users, since mkfs is already using 4K
block size as default for quite a while, and the existing bs == ps support is
always there.

But for power users, this allows extra block size support, and may
provide extra test coverage.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

...

This commit is contained in:

Qu Wenruo 2026-06-19 18:24:47 +09:30 • committed by David Sterba

parent 6eb2fe0724

commit 097cdc8462

1 changed files with 4 additions and 9 deletions

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fs/btrfs/fs.c

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