btrfs: allow balancing to dup with multi-device
authorAustin S. Hemmelgarn <ahferroin7@gmail.com>
Wed, 23 Mar 2016 18:22:59 +0000 (14:22 -0400)
committerDavid Sterba <dsterba@suse.com>
Fri, 6 May 2016 13:22:49 +0000 (15:22 +0200)
commit88be159c905a2b4f6d59afa352bef410afb6af02
tree73bd1700dceef391baf8c1a59f4a52d5a8d852ad
parentcf25ce518e8ef9d59b292e51193bed2b023a32da
btrfs: allow balancing to dup with multi-device

Currently, we don't allow the user to try and rebalance to a dup profile
on a multi-device filesystem.  In most cases, this is a perfectly sensible
restriction as raid1 uses the same amount of space and provides better
protection.

However, when reshaping a multi-device filesystem down to a single device
filesystem, this requires the user to convert metadata and system chunks
to single profile before deleting devices, and then convert again to dup,
which leaves a period of time where metadata integrity is reduced.

This patch removes the single-device-only restriction from converting to
dup profile to remove this potential data integrity reduction.

Signed-off-by: Austin S. Hemmelgarn <ahferroin7@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
fs/btrfs/volumes.c