linux-ext4 - mke2fs accepts block size not mentioned in its man page

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Date:   Fri, 5 Jul 2019 13:35:02 +0800
From:   Qu Wenruo <quwenruo.btrfs@....com>
To:     linux-ext4@...r.kernel.org
Cc:     "linux-btrfs@...r.kernel.org" <linux-btrfs@...r.kernel.org>
Subject: mke2fs accepts block size not mentioned in its man page

Hi,

Just doing some tests on aarch64 with 64K page size.

Man page of mke2fs only mentions 3 valid block size: 1k, 2k, 4k.
But in real world, we can pass 64K as block size for it without any problem:

  $mke2fs -F -t ext3 -b 65536 /dev/loop1
  Warning: blocksize 65536 not usable on most systems.
  mke2fs 1.45.2 (27-May-2019)
  /dev/loop1 contains a btrfs file system
  Discarding device blocks: done
  Creating filesystem with 81920 64k blocks and 81920 inodes
  Filesystem UUID: 311bb224-6d2d-44a7-9790-92c4878d6549
  [...]

It's great to see mke2fs accepts 64K as nodesize, which allows
btrfs-convert to work.
(If blocksize is default to 4K or doesn't accept 64K page size,
btrfs-convert can work but can't be mounted on system with 64K page size)

Shouldn't the man page mention all valid values?

Thanks,
Qu

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