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/ext4.h b/fs/ext4/ext4.h
index 1b0c173..0bd3918 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -683,7 +683,8 @@
__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__
diff --git a/fs/ext4/ext4_sb.h b/fs/ext4/ext4_sb.h
index 4e4d9cc..50ab116 100644
--- a/fs/ext4/ext4_sb.h
+++ b/fs/ext4/ext4_sb.h
@@ -142,6 +142,10 @@
/* 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;
};
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(