Re: [PATCH-v9 3/3] ext4: add optimization for the lazytime mount option

[Michael Kerrisk <mtk.manpages@gmail.com>]

[CC += linux-api@]

On Mon, Feb 2, 2015 at 6:37 AM, Theodore Ts'o <tytso@mit.edu> wrote:
> Add an optimization for the MS_LAZYTIME mount option so that we will
> opportunistically write out any inodes with the I_DIRTY_TIME flag set
> in a particular inode table block when we need to update some inode in
> that inode table block anyway.
>
> Also add some temporary code so that we can set the lazytime mount
> option without needing a modified /sbin/mount program which can set
> MS_LAZYTIME.  We can eventually make this go away once util-linux has
> added support.
>
> Google-Bug-Id: 18297052
>
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> ---
>  fs/ext4/inode.c             | 64 +++++++++++++++++++++++++++++++++++++++++++--
>  fs/ext4/super.c             | 10 +++++++
>  include/trace/events/ext4.h | 30 +++++++++++++++++++++
>  3 files changed, 102 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 628df5b..9193ea1 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4139,6 +4139,65 @@ static int ext4_inode_blocks_set(handle_t *handle,
>         return 0;
>  }
>
> +struct other_inode {
> +       unsigned long           orig_ino;
> +       struct ext4_inode       *raw_inode;
> +};
> +
> +static int other_inode_match(struct inode * inode, unsigned long ino,
> +                            void *data)
> +{
> +       struct other_inode *oi = (struct other_inode *) data;
> +
> +       if ((inode->i_ino != ino) ||
> +           (inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
> +                              I_DIRTY_SYNC | I_DIRTY_DATASYNC)) ||
> +           ((inode->i_state & I_DIRTY_TIME) == 0))
> +               return 0;
> +       spin_lock(&inode->i_lock);
> +       if (((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
> +                               I_DIRTY_SYNC | I_DIRTY_DATASYNC)) == 0) &&
> +           (inode->i_state & I_DIRTY_TIME)) {
> +               struct ext4_inode_info  *ei = EXT4_I(inode);
> +
> +               inode->i_state &= ~(I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED);
> +               spin_unlock(&inode->i_lock);
> +
> +               spin_lock(&ei->i_raw_lock);
> +               EXT4_INODE_SET_XTIME(i_ctime, inode, oi->raw_inode);
> +               EXT4_INODE_SET_XTIME(i_mtime, inode, oi->raw_inode);
> +               EXT4_INODE_SET_XTIME(i_atime, inode, oi->raw_inode);
> +               ext4_inode_csum_set(inode, oi->raw_inode, ei);
> +               spin_unlock(&ei->i_raw_lock);
> +               trace_ext4_other_inode_update_time(inode, oi->orig_ino);
> +               return -1;
> +       }
> +       spin_unlock(&inode->i_lock);
> +       return -1;
> +}
> +
> +/*
> + * Opportunistically update the other time fields for other inodes in
> + * the same inode table block.
> + */
> +static void ext4_update_other_inodes_time(struct super_block *sb,
> +                                         unsigned long orig_ino, char *buf)
> +{
> +       struct other_inode oi;
> +       unsigned long ino;
> +       int i, inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
> +       int inode_size = EXT4_INODE_SIZE(sb);
> +
> +       oi.orig_ino = orig_ino;
> +       ino = orig_ino & ~(inodes_per_block - 1);
> +       for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) {
> +               if (ino == orig_ino)
> +                       continue;
> +               oi.raw_inode = (struct ext4_inode *) buf;
> +               (void) find_inode_nowait(sb, ino, other_inode_match, &oi);
> +       }
> +}
> +
>  /*
>   * Post the struct inode info into an on-disk inode location in the
>   * buffer-cache.  This gobbles the caller's reference to the
> @@ -4248,10 +4307,11 @@ static int ext4_do_update_inode(handle_t *handle,
>                                 cpu_to_le16(ei->i_extra_isize);
>                 }
>         }
> -
>         ext4_inode_csum_set(inode, raw_inode, ei);
> -
>         spin_unlock(&ei->i_raw_lock);
> +       if (inode->i_sb->s_flags & MS_LAZYTIME)
> +               ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
> +                                             bh->b_data);
>
>         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
>         rc = ext4_handle_dirty_metadata(handle, NULL, bh);
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 74c5f53..362b23c 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1139,6 +1139,7 @@ enum {
>         Opt_noquota, Opt_barrier, Opt_nobarrier, Opt_err,
>         Opt_usrquota, Opt_grpquota, Opt_i_version,
>         Opt_stripe, Opt_delalloc, Opt_nodelalloc, Opt_mblk_io_submit,
> +       Opt_lazytime, Opt_nolazytime,
>         Opt_nomblk_io_submit, Opt_block_validity, Opt_noblock_validity,
>         Opt_inode_readahead_blks, Opt_journal_ioprio,
>         Opt_dioread_nolock, Opt_dioread_lock,
> @@ -1202,6 +1203,8 @@ static const match_table_t tokens = {
>         {Opt_i_version, "i_version"},
>         {Opt_stripe, "stripe=%u"},
>         {Opt_delalloc, "delalloc"},
> +       {Opt_lazytime, "lazytime"},
> +       {Opt_nolazytime, "nolazytime"},
>         {Opt_nodelalloc, "nodelalloc"},
>         {Opt_removed, "mblk_io_submit"},
>         {Opt_removed, "nomblk_io_submit"},
> @@ -1459,6 +1462,12 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
>         case Opt_i_version:
>                 sb->s_flags |= MS_I_VERSION;
>                 return 1;
> +       case Opt_lazytime:
> +               sb->s_flags |= MS_LAZYTIME;
> +               return 1;
> +       case Opt_nolazytime:
> +               sb->s_flags &= ~MS_LAZYTIME;
> +               return 1;
>         }
>
>         for (m = ext4_mount_opts; m->token != Opt_err; m++)
> @@ -5020,6 +5029,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
>         }
>  #endif
>
> +       *flags = (*flags & ~MS_LAZYTIME) | (sb->s_flags & MS_LAZYTIME);
>         ext4_msg(sb, KERN_INFO, "re-mounted. Opts: %s", orig_data);
>         kfree(orig_data);
>         return 0;
> diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
> index 6cfb841..6e5abd6 100644
> --- a/include/trace/events/ext4.h
> +++ b/include/trace/events/ext4.h
> @@ -73,6 +73,36 @@ struct extent_status;
>         { FALLOC_FL_ZERO_RANGE,         "ZERO_RANGE"})
>
>
> +TRACE_EVENT(ext4_other_inode_update_time,
> +       TP_PROTO(struct inode *inode, ino_t orig_ino),
> +
> +       TP_ARGS(inode, orig_ino),
> +
> +       TP_STRUCT__entry(
> +               __field(        dev_t,  dev                     )
> +               __field(        ino_t,  ino                     )
> +               __field(        ino_t,  orig_ino                )
> +               __field(        uid_t,  uid                     )
> +               __field(        gid_t,  gid                     )
> +               __field(        __u16, mode                     )
> +       ),
> +
> +       TP_fast_assign(
> +               __entry->orig_ino = orig_ino;
> +               __entry->dev    = inode->i_sb->s_dev;
> +               __entry->ino    = inode->i_ino;
> +               __entry->uid    = i_uid_read(inode);
> +               __entry->gid    = i_gid_read(inode);
> +               __entry->mode   = inode->i_mode;
> +       ),
> +
> +       TP_printk("dev %d,%d orig_ino %lu ino %lu mode 0%o uid %u gid %u",
> +                 MAJOR(__entry->dev), MINOR(__entry->dev),
> +                 (unsigned long) __entry->orig_ino,
> +                 (unsigned long) __entry->ino, __entry->mode,
> +                 __entry->uid, __entry->gid)
> +);
> +
>  TRACE_EVENT(ext4_free_inode,
>         TP_PROTO(struct inode *inode),
>
> --
> 2.1.0
>
> --
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-- 
Michael Kerrisk Linux man-pages maintainer;
http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface", http://blog.man7.org/