btrfs: start qgroup ioctl transactions on the quota root

The qgroup ioctls update the quota tree, but they currently start their
transactions using the root of the inode passed to the ioctl. This makes
the transaction reservation depend on the path used for the ioctl instead
of the tree being modified.

Start qgroup ioctl transactions on the quota root instead. Take a reference
to fs_info->quota_root under qgroup_ioctl_lock before starting the
transaction, because quota disable can clear and put fs_info->quota_root
after the early quota-enabled check. Keep the reference until the
transaction handle is ended.

Suggested-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Dongjiang Zhu <zhudongjiang@fnnas.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

0 files changed, 0 insertions, 0 deletions