ext4: Track lifetime disk writes

Add a new superblock value which tracks the lifetime amount of writes
to the filesystem.  This is useful in estimating the amount of wear on
solid state drives (SSD's) caused by writes to the filesystem.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/ext4/ext4_sb.h b/fs/ext4/ext4_sb.h
index 4e4d9cc3f40d..50ab1169c378 100644
--- a/fs/ext4/ext4_sb.h
+++ b/fs/ext4/ext4_sb.h
@@ -142,6 +142,10 @@ struct ext4_sb_info {
         /* locality groups */
         struct ext4_locality_group *s_locality_groups;
 
+        /* for write statistics */
+        unsigned long s_sectors_written_start;
+        u64 s_kbytes_written;
+
         unsigned int s_log_groups_per_flex;
         struct flex_groups *s_flex_groups;
 };