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, 2 insertions, 1 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 1b0c1736463..0bd39188531 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -683,7 +683,8 @@ struct ext4_super_block {
         __u8    s_log_groups_per_flex;  /* FLEX_BG group size */
         __u8    s_reserved_char_pad2;
         __le16  s_reserved_pad;
-        __u32   s_reserved[162];        /* Padding to the end of the block */
+        __le64  s_kbytes_written;       /* nr of lifetime kilobytes written */
+        __u32   s_reserved[160];        /* Padding to the end of the block */
 };
 
 #ifdef __KERNEL__