xfs: cull unnecessary icdinode fields

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@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

2 files changed, 19 insertions, 45 deletions

diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
index e832bb2ab4f9..c0fe062b567a 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 adcc9bfe02e9..7b8b1b97918b 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);