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Commit 49cc180c authored by David Sterba's avatar David Sterba
Browse files

btrfs: raid56: allow the exact minimum number of devices for balance convert 



The minimum number of devices for RAID5 is 2, though this is only a bit
expensive RAID1, and for RAID6 it's 3, which is a triple copy that works
only 3 devices.

mkfs.btrfs allows that and mounting such filesystem also works, so the
conversion via balance filters is inconsistent with the others and we
should not prevent it.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 0ee5f8ae

fs/btrfs/volumes.c

+4 −3
Original line number Diff line number Diff line
@@ -4080,11 +4080,12 @@ int btrfs_balance(struct btrfs_fs_info *fs_info, 
	allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE | BTRFS_BLOCK_GROUP_DUP;

	if (num_devices > 1)

		allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);

	if (num_devices > 2)

	if (num_devices >= 2)

		allowed |= BTRFS_BLOCK_GROUP_RAID5;

	if (num_devices >= 3)

		allowed |= BTRFS_BLOCK_GROUP_RAID6;

	if (num_devices > 3)

		allowed |= (BTRFS_BLOCK_GROUP_RAID10 |

			    BTRFS_BLOCK_GROUP_RAID6);

		allowed |= BTRFS_BLOCK_GROUP_RAID10;

	if (validate_convert_profile(&bctl->data, allowed)) {

		int index = btrfs_bg_flags_to_raid_index(bctl->data.target);