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Re: [PATCH 3/9] xfs: cull unnecessary icdinode fields

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 3/9] xfs: cull unnecessary icdinode fields
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Mon, 8 Feb 2016 10:29:20 -0500
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1454905461-2773-4-git-send-email-david@xxxxxxxxxxxxx>
References: <1454905461-2773-1-git-send-email-david@xxxxxxxxxxxxx> <1454905461-2773-4-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.24 (2015-08-30)
On Mon, Feb 08, 2016 at 03:24:15PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> Now that the struct xfs_icdinode is not directly related to the
> on-disk format, we can cull things in it we really don't need to
> store:
> 
>       - magic number never changes
>       - padding is not necessary
>       - next_unlinked is never used
>       - inode number is redundant
>       - uuid is redundant
>       - lsn is accessed directly from dinode
>       - inode CRC is only accessed directly from dinode
> 
> Hence we can remove these from the struct xfs_icdinode and redirect
> the code that uses them to the xfs_dinode appripriately.  This
> reduces the size of the struct icdinode from 152 bytes to 88 bytes,
> and removes a fair chunk of unnecessary code, too.
> 
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---

Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>

>  fs/xfs/libxfs/xfs_inode_buf.c | 39 +++++++++++++--------------------------
>  fs/xfs/libxfs/xfs_inode_buf.h | 25 ++++++-------------------
>  fs/xfs/xfs_inode.c            | 19 +------------------
>  fs/xfs/xfs_inode_item.c       | 19 +++++++++++--------
>  4 files changed, 31 insertions(+), 71 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
> index 26e3c46..17ff4e8 100644
> --- a/fs/xfs/libxfs/xfs_inode_buf.c
> +++ b/fs/xfs/libxfs/xfs_inode_buf.c
> @@ -202,7 +202,6 @@ xfs_inode_from_disk(
>       struct xfs_icdinode     *to = &ip->i_d;
>       struct inode            *inode = VFS_I(ip);
>  
> -     to->di_magic = be16_to_cpu(from->di_magic);
>       to->di_mode = be16_to_cpu(from->di_mode);
>       to->di_version = from ->di_version;
>       to->di_format = from->di_format;
> @@ -212,7 +211,6 @@ xfs_inode_from_disk(
>       to->di_nlink = be32_to_cpu(from->di_nlink);
>       to->di_projid_lo = be16_to_cpu(from->di_projid_lo);
>       to->di_projid_hi = be16_to_cpu(from->di_projid_hi);
> -     memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
>       to->di_flushiter = be16_to_cpu(from->di_flushiter);
>  
>       /*
> @@ -245,24 +243,22 @@ xfs_inode_from_disk(
>               to->di_crtime.t_sec = be32_to_cpu(from->di_crtime.t_sec);
>               to->di_crtime.t_nsec = be32_to_cpu(from->di_crtime.t_nsec);
>               to->di_flags2 = be64_to_cpu(from->di_flags2);
> -             to->di_ino = be64_to_cpu(from->di_ino);
> -             to->di_lsn = be64_to_cpu(from->di_lsn);
> -             memcpy(to->di_pad2, from->di_pad2, sizeof(to->di_pad2));
> -             uuid_copy(&to->di_uuid, &from->di_uuid);
>       }
>  }
>  
>  void
>  xfs_inode_to_disk(
>       struct xfs_inode        *ip,
> -     struct xfs_dinode       *to)
> +     struct xfs_dinode       *to,
> +     xfs_lsn_t               lsn)
>  {
>       struct xfs_icdinode     *from = &ip->i_d;
>       struct inode            *inode = VFS_I(ip);
>  
> -     to->di_magic = cpu_to_be16(from->di_magic);
> +     to->di_magic = cpu_to_be16(XFS_DINODE_MAGIC);
> +
>       to->di_mode = cpu_to_be16(from->di_mode);
> -     to->di_version = from ->di_version;
> +     to->di_version = from->di_version;
>       to->di_format = from->di_format;
>       to->di_onlink = cpu_to_be16(from->di_onlink);
>       to->di_uid = cpu_to_be32(from->di_uid);
> @@ -270,8 +266,8 @@ xfs_inode_to_disk(
>       to->di_nlink = cpu_to_be32(from->di_nlink);
>       to->di_projid_lo = cpu_to_be16(from->di_projid_lo);
>       to->di_projid_hi = cpu_to_be16(from->di_projid_hi);
> -     memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
>  
> +     memset(to->di_pad, 0, sizeof(to->di_pad));
>       to->di_atime.t_sec = cpu_to_be32(inode->i_atime.tv_sec);
>       to->di_atime.t_nsec = cpu_to_be32(inode->i_atime.tv_nsec);
>       to->di_mtime.t_sec = cpu_to_be32(inode->i_mtime.tv_sec);
> @@ -296,10 +292,11 @@ xfs_inode_to_disk(
>               to->di_crtime.t_sec = cpu_to_be32(from->di_crtime.t_sec);
>               to->di_crtime.t_nsec = cpu_to_be32(from->di_crtime.t_nsec);
>               to->di_flags2 = cpu_to_be64(from->di_flags2);
> -             to->di_ino = cpu_to_be64(from->di_ino);
> -             to->di_lsn = cpu_to_be64(from->di_lsn);
> -             memcpy(to->di_pad2, from->di_pad2, sizeof(to->di_pad2));
> -             uuid_copy(&to->di_uuid, &from->di_uuid);
> +
> +             to->di_ino = cpu_to_be64(ip->i_ino);
> +             to->di_lsn = cpu_to_be64(lsn);
> +             memset(to->di_pad2, 0, sizeof(to->di_pad2));
> +             uuid_copy(&to->di_uuid, &ip->i_mount->m_sb.sb_meta_uuid);
>               to->di_flushiter = 0;
>       } else {
>               to->di_flushiter = cpu_to_be16(from->di_flushiter);
> @@ -434,13 +431,10 @@ xfs_iread(
>           !(mp->m_flags & XFS_MOUNT_IKEEP)) {
>               /* initialise the on-disk inode core */
>               memset(&ip->i_d, 0, sizeof(ip->i_d));
> -             ip->i_d.di_magic = XFS_DINODE_MAGIC;
>               ip->i_d.di_gen = prandom_u32();
> -             if (xfs_sb_version_hascrc(&mp->m_sb)) {
> +             if (xfs_sb_version_hascrc(&mp->m_sb))
>                       ip->i_d.di_version = 3;
> -                     ip->i_d.di_ino = ip->i_ino;
> -                     uuid_copy(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid);
> -             } else
> +             else
>                       ip->i_d.di_version = 2;
>               return 0;
>       }
> @@ -484,16 +478,10 @@ xfs_iread(
>                * Partial initialisation of the in-core inode. Just the bits
>                * that xfs_ialloc won't overwrite or relies on being correct.
>                */
> -             ip->i_d.di_magic = be16_to_cpu(dip->di_magic);
>               ip->i_d.di_version = dip->di_version;
>               ip->i_d.di_gen = be32_to_cpu(dip->di_gen);
>               ip->i_d.di_flushiter = be16_to_cpu(dip->di_flushiter);
>  
> -             if (dip->di_version == 3) {
> -                     ip->i_d.di_ino = be64_to_cpu(dip->di_ino);
> -                     uuid_copy(&ip->i_d.di_uuid, &dip->di_uuid);
> -             }
> -
>               /*
>                * Make sure to pull in the mode here as well in
>                * case the inode is released without being used.
> @@ -514,7 +502,6 @@ xfs_iread(
>        */
>       if (ip->i_d.di_version == 1) {
>               ip->i_d.di_version = 2;
> -             memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
>               ip->i_d.di_nlink = ip->i_d.di_onlink;
>               ip->i_d.di_onlink = 0;
>               xfs_set_projid(ip, 0);
> diff --git a/fs/xfs/libxfs/xfs_inode_buf.h b/fs/xfs/libxfs/xfs_inode_buf.h
> index adcc9bf..7b8b1b9 100644
> --- a/fs/xfs/libxfs/xfs_inode_buf.h
> +++ b/fs/xfs/libxfs/xfs_inode_buf.h
> @@ -22,24 +22,22 @@ struct xfs_inode;
>  struct xfs_dinode;
>  
>  /*
> - * In memory representation of the XFS inode. This is held in the in-core
> - * struct xfs_inode to represent the on disk values, but no longer needs to 
> be
> - * identical to the on-disk structure as it is always translated to on-disk
> + * In memory representation of the XFS inode. This is held in the in-core 
> struct
> + * xfs_inode and represents the current on disk values but the structure is 
> not
> + * in on-disk format.  That is, this structure is always translated to 
> on-disk
>   * format specific structures at the appropriate time.
>   */
>  struct xfs_icdinode {
> -     __uint16_t      di_magic;       /* inode magic # = XFS_DINODE_MAGIC */
>       __uint16_t      di_mode;        /* mode and type of file */
>       __int8_t        di_version;     /* inode version */
>       __int8_t        di_format;      /* format of di_c data */
>       __uint16_t      di_onlink;      /* old number of links to file */
> +     __uint16_t      di_flushiter;   /* incremented on flush */
>       __uint32_t      di_uid;         /* owner's user id */
>       __uint32_t      di_gid;         /* owner's group id */
>       __uint32_t      di_nlink;       /* number of links to file */
>       __uint16_t      di_projid_lo;   /* lower part of owner's project id */
>       __uint16_t      di_projid_hi;   /* higher part of owner's project id */
> -     __uint8_t       di_pad[6];      /* unused, zeroed space */
> -     __uint16_t      di_flushiter;   /* incremented on flush */
>       xfs_fsize_t     di_size;        /* number of bytes in file */
>       xfs_rfsblock_t  di_nblocks;     /* # of direct & btree blocks used */
>       xfs_extlen_t    di_extsize;     /* basic/minimum extent size for file */
> @@ -52,22 +50,10 @@ struct xfs_icdinode {
>       __uint16_t      di_flags;       /* random flags, XFS_DIFLAG_... */
>       __uint32_t      di_gen;         /* generation number */
>  
> -     /* di_next_unlinked is the only non-core field in the old dinode */
> -     xfs_agino_t     di_next_unlinked;/* agi unlinked list ptr */
> -
> -     /* start of the extended dinode, writable fields */
> -     __uint32_t      di_crc;         /* CRC of the inode */
>       __uint64_t      di_changecount; /* number of attribute changes */
> -     xfs_lsn_t       di_lsn;         /* flush sequence */
>       __uint64_t      di_flags2;      /* more random flags */
> -     __uint8_t       di_pad2[16];    /* more padding for future expansion */
>  
> -     /* fields only written to during inode creation */
>       xfs_ictimestamp_t di_crtime;    /* time created */
> -     xfs_ino_t       di_ino;         /* inode number */
> -     uuid_t          di_uuid;        /* UUID of the filesystem */
> -
> -     /* structure must be padded to 64 bit alignment */
>  };
>  
>  /*
> @@ -86,7 +72,8 @@ int xfs_imap_to_bp(struct xfs_mount *, struct xfs_trans *,
>  int  xfs_iread(struct xfs_mount *, struct xfs_trans *,
>                 struct xfs_inode *, uint);
>  void xfs_dinode_calc_crc(struct xfs_mount *, struct xfs_dinode *);
> -void xfs_inode_to_disk(struct xfs_inode *ip, struct xfs_dinode *to);
> +void xfs_inode_to_disk(struct xfs_inode *ip, struct xfs_dinode *to,
> +                       xfs_lsn_t lsn);
>  void xfs_inode_from_disk(struct xfs_inode *ip, struct xfs_dinode *from);
>  void xfs_log_dinode_to_disk(struct xfs_log_dinode *from,
>                              struct xfs_dinode *to);
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 9ad9e35..45acdee 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -809,7 +809,6 @@ xfs_ialloc(
>       ip->i_d.di_uid = xfs_kuid_to_uid(current_fsuid());
>       ip->i_d.di_gid = xfs_kgid_to_gid(current_fsgid());
>       xfs_set_projid(ip, prid);
> -     memset(&(ip->i_d.di_pad[0]), 0, sizeof(ip->i_d.di_pad));
>  
>       if (pip && XFS_INHERIT_GID(pip)) {
>               ip->i_d.di_gid = pip->i_d.di_gid;
> @@ -847,13 +846,8 @@ xfs_ialloc(
>       ip->i_d.di_flags = 0;
>  
>       if (ip->i_d.di_version == 3) {
> -             ASSERT(ip->i_d.di_ino == ino);
> -             ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid));
> -             ip->i_d.di_crc = 0;
>               ip->i_d.di_changecount = 1;
> -             ip->i_d.di_lsn = 0;
>               ip->i_d.di_flags2 = 0;
> -             memset(&(ip->i_d.di_pad2[0]), 0, sizeof(ip->i_d.di_pad2));
>               ip->i_d.di_crtime.t_sec = (__int32_t)tv.tv_sec;
>               ip->i_d.di_crtime.t_nsec = (__int32_t)tv.tv_nsec;
>       }
> @@ -3464,13 +3458,6 @@ xfs_iflush_int(
>                       __func__, ip->i_ino, be16_to_cpu(dip->di_magic), dip);
>               goto corrupt_out;
>       }
> -     if (XFS_TEST_ERROR(ip->i_d.di_magic != XFS_DINODE_MAGIC,
> -                             mp, XFS_ERRTAG_IFLUSH_2, XFS_RANDOM_IFLUSH_2)) {
> -             xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
> -                     "%s: Bad inode %Lu, ptr 0x%p, magic number 0x%x",
> -                     __func__, ip->i_ino, ip, ip->i_d.di_magic);
> -             goto corrupt_out;
> -     }
>       if (S_ISREG(ip->i_d.di_mode)) {
>               if (XFS_TEST_ERROR(
>                   (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS) &&
> @@ -3529,7 +3516,7 @@ xfs_iflush_int(
>        * copy out the core of the inode, because if the inode is dirty at all
>        * the core must be.
>        */
> -     xfs_inode_to_disk(ip, dip);
> +     xfs_inode_to_disk(ip, dip, iip->ili_item.li_lsn);
>  
>       /* Wrap, we never let the log put out DI_MAX_FLUSH */
>       if (ip->i_d.di_flushiter == DI_MAX_FLUSH)
> @@ -3581,10 +3568,6 @@ xfs_iflush_int(
>        */
>       xfs_buf_attach_iodone(bp, xfs_iflush_done, &iip->ili_item);
>  
> -     /* update the lsn in the on disk inode if required */
> -     if (ip->i_d.di_version == 3)
> -             dip->di_lsn = cpu_to_be64(iip->ili_item.li_lsn);
> -
>       /* generate the checksum. */
>       xfs_dinode_calc_crc(mp, dip);
>  
> diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
> index 9dcbf58..588d1b4 100644
> --- a/fs/xfs/xfs_inode_item.c
> +++ b/fs/xfs/xfs_inode_item.c
> @@ -325,12 +325,14 @@ xfs_inode_item_format_attr_fork(
>  static void
>  xfs_inode_to_log_dinode(
>       struct xfs_inode        *ip,
> -     struct xfs_log_dinode   *to)
> +     struct xfs_log_dinode   *to,
> +     xfs_lsn_t               lsn)
>  {
>       struct xfs_icdinode     *from = &ip->i_d;
>       struct inode            *inode = VFS_I(ip);
>  
> -     to->di_magic = from->di_magic;
> +     to->di_magic = XFS_DINODE_MAGIC;
> +
>       to->di_mode = from->di_mode;
>       to->di_version = from->di_version;
>       to->di_format = from->di_format;
> @@ -340,8 +342,8 @@ xfs_inode_to_log_dinode(
>       to->di_nlink = from->di_nlink;
>       to->di_projid_lo = from->di_projid_lo;
>       to->di_projid_hi = from->di_projid_hi;
> -     memcpy(to->di_pad, from->di_pad, sizeof(to->di_pad));
>  
> +     memset(to->di_pad, 0, sizeof(to->di_pad));
>       to->di_atime.t_sec = inode->i_atime.tv_sec;
>       to->di_atime.t_nsec = inode->i_atime.tv_nsec;
>       to->di_mtime.t_sec = inode->i_mtime.tv_sec;
> @@ -366,10 +368,11 @@ xfs_inode_to_log_dinode(
>               to->di_crtime.t_sec = from->di_crtime.t_sec;
>               to->di_crtime.t_nsec = from->di_crtime.t_nsec;
>               to->di_flags2 = from->di_flags2;
> -             to->di_ino = from->di_ino;
> -             to->di_lsn = from->di_lsn;
> -             memcpy(to->di_pad2, from->di_pad2, sizeof(to->di_pad2));
> -             uuid_copy(&to->di_uuid, &from->di_uuid);
> +
> +             to->di_ino = ip->i_ino;
> +             to->di_lsn = lsn;
> +             memset(to->di_pad2, 0, sizeof(to->di_pad2));
> +             uuid_copy(&to->di_uuid, &ip->i_mount->m_sb.sb_meta_uuid);
>               to->di_flushiter = 0;
>       } else {
>               to->di_flushiter = from->di_flushiter;
> @@ -390,7 +393,7 @@ xfs_inode_item_format_core(
>       struct xfs_log_dinode   *dic;
>  
>       dic = xlog_prepare_iovec(lv, vecp, XLOG_REG_TYPE_ICORE);
> -     xfs_inode_to_log_dinode(ip, dic);
> +     xfs_inode_to_log_dinode(ip, dic, ip->i_itemp->ili_item.li_lsn);
>       xlog_finish_iovec(lv, *vecp, xfs_log_dinode_size(ip->i_d.di_version));
>  }
>  
> -- 
> 2.5.0
> 
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