Btrfs: read device stats on mount, write modified ones during commit

The device statistics are written into the device tree with each
transaction commit. Only modified statistics are written.
When a filesystem is mounted, the device statistics for each involved
device are read from the device tree and used to initialize the
counters.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 6798f8674b13..3406a88ca83e 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -109,6 +109,7 @@ struct btrfs_device {
 
         /* disk I/O failure stats. For detailed description refer to
          * enum btrfs_dev_stat_values in ioctl.h */
+        int dev_stats_valid;
         int dev_stats_dirty; /* counters need to be written to disk */
         atomic_t dev_stat_values[BTRFS_DEV_STAT_VALUES_MAX];
 };
@@ -293,6 +294,9 @@ 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);
+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);
 
 static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
                                       int index)