Btrfs: add ioctl to get and reset the device stats

An ioctl interface is added to get the device statistic counters.
A second ioctl is added to atomically get and reset these counters.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>

1 files changed, 14 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 5bf05e28b829..497c530724cf 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -285,6 +285,16 @@ enum btrfs_dev_stat_values {
         BTRFS_DEV_STAT_VALUES_MAX
 };
 
+struct btrfs_ioctl_get_dev_stats {
+        __u64 devid;                            /* in */
+        __u64 nr_items;                         /* in/out */
+
+        /* out values: */
+        __u64 values[BTRFS_DEV_STAT_VALUES_MAX];
+
+        __u64 unused[128 - 2 - BTRFS_DEV_STAT_VALUES_MAX]; /* pad to 1k */
+};
+
 #define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
                                    struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
@@ -349,5 +359,9 @@ enum btrfs_dev_stat_values {
                                         struct btrfs_ioctl_ino_path_args)
 #define BTRFS_IOC_LOGICAL_INO _IOWR(BTRFS_IOCTL_MAGIC, 36, \
                                         struct btrfs_ioctl_ino_path_args)
+#define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \
+                                      struct btrfs_ioctl_get_dev_stats)
+#define BTRFS_IOC_GET_AND_RESET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 53, \
+                                        struct btrfs_ioctl_get_dev_stats)
 
 #endif