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>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 15baf94..0f8c354 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3046,6 +3046,28 @@
return ret;
}
+static long btrfs_ioctl_get_dev_stats(struct btrfs_root *root,
+ void __user *arg, int reset_after_read)
+{
+ struct btrfs_ioctl_get_dev_stats *sa;
+ int ret;
+
+ if (reset_after_read && !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ sa = memdup_user(arg, sizeof(*sa));
+ if (IS_ERR(sa))
+ return PTR_ERR(sa);
+
+ ret = btrfs_get_dev_stats(root, sa, reset_after_read);
+
+ if (copy_to_user(arg, sa, sizeof(*sa)))
+ ret = -EFAULT;
+
+ kfree(sa);
+ return ret;
+}
+
static long btrfs_ioctl_ino_to_path(struct btrfs_root *root, void __user *arg)
{
int ret = 0;
@@ -3434,6 +3456,10 @@
return btrfs_ioctl_balance_ctl(root, arg);
case BTRFS_IOC_BALANCE_PROGRESS:
return btrfs_ioctl_balance_progress(root, argp);
+ case BTRFS_IOC_GET_DEV_STATS:
+ return btrfs_ioctl_get_dev_stats(root, argp, 0);
+ case BTRFS_IOC_GET_AND_RESET_DEV_STATS:
+ return btrfs_ioctl_get_dev_stats(root, argp, 1);
}
return -ENOTTY;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 5bf05e2..497c530 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -285,6 +285,16 @@
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 @@
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
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2915521..a112b75 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4673,3 +4673,37 @@
btrfs_dev_stat_read(dev,
BTRFS_DEV_STAT_GENERATION_ERRS));
}
+
+int btrfs_get_dev_stats(struct btrfs_root *root,
+ struct btrfs_ioctl_get_dev_stats *stats,
+ int reset_after_read)
+{
+ struct btrfs_device *dev;
+ struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
+ int i;
+
+ mutex_lock(&fs_devices->device_list_mutex);
+ dev = btrfs_find_device(root, stats->devid, NULL, NULL);
+ mutex_unlock(&fs_devices->device_list_mutex);
+
+ if (!dev) {
+ printk(KERN_WARNING
+ "btrfs: get dev_stats failed, device not found\n");
+ return -ENODEV;
+ } else if (reset_after_read) {
+ for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++) {
+ if (stats->nr_items > i)
+ stats->values[i] =
+ btrfs_dev_stat_read_and_reset(dev, i);
+ else
+ btrfs_dev_stat_reset(dev, i);
+ }
+ } else {
+ for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++)
+ if (stats->nr_items > i)
+ stats->values[i] = btrfs_dev_stat_read(dev, i);
+ }
+ if (stats->nr_items > BTRFS_DEV_STAT_VALUES_MAX)
+ stats->nr_items = BTRFS_DEV_STAT_VALUES_MAX;
+ return 0;
+}
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 193b283..6798f86 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -290,6 +290,9 @@
u64 logical, int mirror_num);
void btrfs_dev_stat_print_on_error(struct btrfs_device *device);
void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index);
+int btrfs_get_dev_stats(struct btrfs_root *root,
+ struct btrfs_ioctl_get_dev_stats *stats,
+ int reset_after_read);
static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
int index)