dont-let-dirty-time-inodes-get-more-than-a-day-stale

   1 vfs: don't let the dirty time inodes get more than a day stale
   2
   3 Guarantee that the on-disk timestamps will be no more than 24 hours
   4 stale.
   5
   6 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
   7 ---
   8  fs/fs-writeback.c  |  1 +
   9  fs/inode.c         | 19 +++++++++++++++++++
  10  include/linux/fs.h |  1 +
  11  3 files changed, 21 insertions(+)
  12
  13 diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
  14 index ef8c5d8..529480a 100644
  15 --- a/fs/fs-writeback.c
  16 +++ b/fs/fs-writeback.c
  17 @@ -1143,6 +1143,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
  18         if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
  19                 trace_writeback_dirty_inode_start(inode, flags);
  20
  21 +               inode->i_ts_dirty_day = 0;
  22                 if (sb->s_op->dirty_inode)
  23                         sb->s_op->dirty_inode(inode, flags);
  24
  25 diff --git a/fs/inode.c b/fs/inode.c
  26 index 009d9c5..c8ad78b 100644
  27 --- a/fs/inode.c
  28 +++ b/fs/inode.c
  29 @@ -1510,6 +1510,8 @@ static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
  30   */
  31  static int update_time(struct inode *inode, struct timespec *time, int flags)
  32  {
  33 +       struct timespec uptime;
  34 +       unsigned short days_since_boot;
  35         int ret;
  36
  37         if (inode->i_op->is_readonly) {
  38 @@ -1532,6 +1534,22 @@ static int update_time(struct inode *inode, struct timespec *time, int flags)
  39             !(inode->i_state & (I_DIRTY_SYNC | I_DIRTY_DATASYNC))) {
  40                 if (inode->i_state & I_DIRTY_TIME)
  41                         return 0;
  42 +               get_monotonic_boottime(&uptime);
  43 +               days_since_boot = div_u64(uptime.tv_sec, 86400);
  44 +               /*
  45 +                * If i_ts_dirty_day is zero, then either we have not
  46 +                * deferred timestamp updates, or the system has been
  47 +                * up for less than a day (so days_since_boot is
  48 +                * zero), so we can defer timestamp updates in that
  49 +                * case.  If a day or more has passed, then
  50 +                * i_ts_dirty_day will be different from
  51 +                * days_since_boot, and then we should update the
  52 +                * on-disk inode and then we can clear i_ts_dirty_day.
  53 +                */
  54 +               if (inode->i_ts_dirty_day &&
  55 +                   (inode->i_ts_dirty_day != days_since_boot))
  56 +                       goto force_dirty;
  57 +
  58                 spin_lock(&inode->i_lock);
  59                 if (inode->i_state & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
  60                         spin_unlock(&inode->i_lock);
  61 @@ -1542,6 +1560,7 @@ static int update_time(struct inode *inode, struct timespec *time, int flags)
  62                         return 0;
  63                 }
  64                 inode->i_state |= I_DIRTY_TIME;
  65 +               inode->i_ts_dirty_day = days_since_boot;
  66                 spin_unlock(&inode->i_lock);
  67                 inode_requeue_dirtytime(inode);
  68                 return 0;
  69 diff --git a/include/linux/fs.h b/include/linux/fs.h
  70 index 6a6f56b..070f6c6 100644
  71 --- a/include/linux/fs.h
  72 +++ b/include/linux/fs.h
  73 @@ -575,6 +575,7 @@ struct inode {
  74         struct timespec         i_ctime;
  75         spinlock_t              i_lock; /* i_blocks, i_bytes, maybe i_size */
  76         unsigned short          i_bytes;
  77 +       unsigned short          i_ts_dirty_day;
  78         unsigned int            i_blkbits;
  79         blkcnt_t                i_blocks;
  80