Correct allowed raid levels on balance.

Raid5 with 3 devices is well defined while the old logic allowed
raid5 only with a minimum of 4 devices when converting the block group
profile via btrfs balance. Creating a raid5 with just three devices
using mkfs.btrfs worked always as expected. This is now fixed and the
whole logic is rewritten.

Signed-off-by: Andreas Philipp <philipp.andreas@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a191bac31d853745c69b7a73d8aeec54d473615c..062e93069c5ea7addc86365d8a824f55a2328eb6 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3120,14 +3120,13 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
        allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE;
        if (num_devices == 1)
                allowed |= BTRFS_BLOCK_GROUP_DUP;
-       else if (num_devices < 4)
+       else if (num_devices > 1)
                allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);
-       else
-               allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
-                               BTRFS_BLOCK_GROUP_RAID10 |
-                               BTRFS_BLOCK_GROUP_RAID5 |
-                               BTRFS_BLOCK_GROUP_RAID6);
-
+       if (num_devices > 2)
+               allowed |= BTRFS_BLOCK_GROUP_RAID5;
+       if (num_devices > 3)
+               allowed |= (BTRFS_BLOCK_GROUP_RAID10 |
+                           BTRFS_BLOCK_GROUP_RAID6);
        if ((bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
            (!alloc_profile_is_valid(bctl->data.target, 1) ||
             (bctl->data.target & ~allowed))) {