btrfs: add ioctl to export size of global metadata reservation
authorJeff Mahoney <jeffm@suse.com>
Fri, 1 Nov 2013 17:07:03 +0000 (13:07 -0400)
committerChris Mason <clm@fb.com>
Tue, 28 Jan 2014 21:19:28 +0000 (13:19 -0800)
commit01e219e8069516cdb98594d417b8bb8d906ed30d
tree0e8ff696017353a46d442bff736050ad451f6f8d
parent3b02a68a636400590dd6831a5fc046f0a7909a77
btrfs: add ioctl to export size of global metadata reservation

btrfs filesystem df output will show the size of the metadata space
and how much of it is used, and the user assumes that the difference
is all usable space. Since that's not actually the case due to the
global metadata reservation, we should provide the full picture to the
user.

This patch adds an ioctl that exports the size of the global metadata
reservation so that btrfs filesystem df can report it.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
fs/btrfs/ioctl.c
include/uapi/linux/btrfs.h