commit fab273595507a9ec7035df6d5512a955d80a80ba
author Qu Wenruo <wqu@suse.com> Wed Sep 25 10:13:27 2019 +0800
committer David Sterba <dsterba@suse.com> Wed Sep 25 16:00:37 2019 +0200
tree 722375c515bfb86b4b9e66cd4fde307e3c90eba1
parent 1fac4a54374f7ef385938f3c6cf7649c0fe4f6cd

btrfs: Fix a regression which we can't convert to SINGLE profile

[BUG]
With v5.3 kernel, we can't convert to SINGLE profile:

  # btrfs balance start -f -dconvert=single $mnt
  ERROR: error during balancing '/mnt/btrfs': Invalid argument
  # dmesg -t | tail
  validate_convert_profile: data profile=0x1000000000000 allowed=0x20 is_valid=1 final=0x1000000000000 ret=1
  BTRFS error (device dm-3): balance: invalid convert data profile single

[CAUSE]
With the extra debug output added, it shows that the @allowed bit is
lacking the special in-memory only SINGLE profile bit.

Thus we fail at that (profile & ~allowed) check.

This regression is caused by commit 081db89b13cb ("btrfs: use raid_attr
to get allowed profiles for balance conversion") and the fact that we
don't use any bit to indicate SINGLE profile on-disk, but uses special
in-memory only bit to help distinguish different profiles.

[FIX]
Add that BTRFS_AVAIL_ALLOC_BIT_SINGLE to @allowed, so the code should be
the same as it was and fix the regression.

Reported-by: Chris Murphy <lists@colorremedies.com>
Fixes: 081db89b13cb ("btrfs: use raid_attr to get allowed profiles for balance conversion")
CC: stable@vger.kernel.org # 5.3+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>