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>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index a376870..30fc27c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2035,6 +2035,8 @@
sbi->s_resgid = EXT4_DEF_RESGID;
sbi->s_inode_readahead_blks = EXT4_DEF_INODE_READAHEAD_BLKS;
sbi->s_sb_block = sb_block;
+ sbi->s_sectors_written_start = part_stat_read(sb->s_bdev->bd_part,
+ sectors[1]);
unlock_kernel();
@@ -2072,6 +2074,7 @@
sb->s_magic = le16_to_cpu(es->s_magic);
if (sb->s_magic != EXT4_SUPER_MAGIC)
goto cantfind_ext4;
+ sbi->s_kbytes_written = le64_to_cpu(es->s_kbytes_written);
/* Set defaults before we parse the mount options */
def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
@@ -2921,6 +2924,10 @@
set_buffer_uptodate(sbh);
}
es->s_wtime = cpu_to_le32(get_seconds());
+ es->s_kbytes_written =
+ cpu_to_le64(EXT4_SB(sb)->s_kbytes_written +
+ ((part_stat_read(sb->s_bdev->bd_part, sectors[1]) -
+ EXT4_SB(sb)->s_sectors_written_start) >> 1));
ext4_free_blocks_count_set(es, percpu_counter_sum_positive(
&EXT4_SB(sb)->s_freeblocks_counter));
es->s_free_inodes_count = cpu_to_le32(percpu_counter_sum_positive(