btrfs: join DEV_STATS ioctls to one

Commit c11d2c236cc260b36 (Btrfs: add ioctl to get and reset the device
stats) introduced two ioctls doing almost the same thing distinguished
by just the ioctl number which encodes "do reset after read". I have
suggested

http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg16604.html

to implement it via the ioctl args. This hasn't happen, and I think we
should use a more clean way to pass flags and should not waste ioctl
numbers.

CC: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: David Sterba <dsterba@suse.cz>

4 files changed, 15 insertions, 15 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9ec23b93e019..3a3f916d7c02 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3065,19 +3065,21 @@ static long btrfs_ioctl_scrub_progress(struct btrfs_root *root,
 }
 
 static long btrfs_ioctl_get_dev_stats(struct btrfs_root *root,
-                                      void __user *arg, int reset_after_read)
+                                      void __user *arg)
 {
         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 ((sa->flags & BTRFS_DEV_STATS_RESET) && !capable(CAP_SYS_ADMIN)) {
+                kfree(sa);
+                return -EPERM;
+        }
+
+        ret = btrfs_get_dev_stats(root, sa);
 
         if (copy_to_user(arg, sa, sizeof(*sa)))
                 ret = -EFAULT;
@@ -3475,9 +3477,7 @@ long btrfs_ioctl(struct file *file, unsigned int
         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 btrfs_ioctl_get_dev_stats(root, argp);
         }
 
         return -ENOTTY;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index e440aa653c30..021c55ed8aed 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -285,9 +285,13 @@ enum btrfs_dev_stat_values {
         BTRFS_DEV_STAT_VALUES_MAX
 };
 
+/* Reset statistics after reading; needs SYS_ADMIN capability */
+#define BTRFS_DEV_STATS_RESET           (1ULL << 0)
+
 struct btrfs_ioctl_get_dev_stats {
         __u64 devid;                            /* in */
         __u64 nr_items;                         /* in/out */
+        __u64 flags;                            /* in/out */
 
         /* out values: */
         __u64 values[BTRFS_DEV_STAT_VALUES_MAX];
@@ -361,7 +365,5 @@ struct btrfs_ioctl_get_dev_stats {
                                         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 ecaad40e7ef4..957bf393ab46 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4890,8 +4890,7 @@ static void btrfs_dev_stat_print_on_load(struct btrfs_device *dev)
 }
 
 int btrfs_get_dev_stats(struct btrfs_root *root,
-                        struct btrfs_ioctl_get_dev_stats *stats,
-                        int reset_after_read)
+                        struct btrfs_ioctl_get_dev_stats *stats)
 {
         struct btrfs_device *dev;
         struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
@@ -4909,7 +4908,7 @@ int btrfs_get_dev_stats(struct btrfs_root *root,
                 printk(KERN_WARNING
                        "btrfs: get dev_stats failed, not yet valid\n");
                 return -ENODEV;
-        } else if (reset_after_read) {
+        } else if (stats->flags & BTRFS_DEV_STATS_RESET) {
                 for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++) {
                         if (stats->nr_items > i)
                                 stats->values[i] =
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 95f6637614db..e404414a95a9 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -293,8 +293,7 @@ struct btrfs_device *btrfs_find_device_for_logical(struct btrfs_root *root,
 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);
+                        struct btrfs_ioctl_get_dev_stats *stats);
 int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info);
 int btrfs_run_dev_stats(struct btrfs_trans_handle *trans,
                         struct btrfs_fs_info *fs_info);