Btrfs: rescan for qgroups

If qgroup tracking is out of sync, a rescan operation can be started. It
iterates the complete extent tree and recalculates all qgroup tracking data.
This is an expensive operation and should not be used unless required.

A filesystem under rescan can still be umounted. The rescan continues on the
next mount.  Status information is provided with a separate ioctl while a
rescan operation is in progress.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 5e39e859a848..5ef0df545a2a 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -376,12 +376,18 @@ struct btrfs_ioctl_get_dev_stats {
 
 #define BTRFS_QUOTA_CTL_ENABLE  1
 #define BTRFS_QUOTA_CTL_DISABLE 2
-#define BTRFS_QUOTA_CTL_RESCAN  3
+#define BTRFS_QUOTA_CTL_RESCAN__NOTUSED 3
 struct btrfs_ioctl_quota_ctl_args {
         __u64 cmd;
         __u64 status;
 };
 
+struct btrfs_ioctl_quota_rescan_args {
+        __u64   flags;
+        __u64   progress;
+        __u64   reserved[6];
+};
+
 struct btrfs_ioctl_qgroup_assign_args {
         __u64 assign;
         __u64 src;
@@ -520,6 +526,10 @@ struct btrfs_ioctl_send_args {
                                struct btrfs_ioctl_qgroup_create_args)
 #define BTRFS_IOC_QGROUP_LIMIT _IOR(BTRFS_IOCTL_MAGIC, 43, \
                                struct btrfs_ioctl_qgroup_limit_args)
+#define BTRFS_IOC_QUOTA_RESCAN _IOW(BTRFS_IOCTL_MAGIC, 44, \
+                               struct btrfs_ioctl_quota_rescan_args)
+#define BTRFS_IOC_QUOTA_RESCAN_STATUS _IOR(BTRFS_IOCTL_MAGIC, 45, \
+                               struct btrfs_ioctl_quota_rescan_args)
 #define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \
                                    char[BTRFS_LABEL_SIZE])
 #define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 50, \