[Cluster-devel] [PATCH 2/4] GFS2: Reduce inode size by using 32-bit i_generation

[Bob Peterson <rpeterso@redhat.com>]

This patch removes variable i_generation from gfs2_inode. In its
place, we use inode->i_generation which is pretty much the same thing,
in 32-bits. The loss of 32 bits should not be a problem.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/glops.c                  |  2 +-
 fs/gfs2/incore.h                 |  9 +++++++--
 fs/gfs2/inode.c                  |  5 +++--
 fs/gfs2/rgrp.c                   | 16 ++++++++--------
 fs/gfs2/rgrp.h                   |  2 +-
 fs/gfs2/super.c                  |  2 +-
 include/uapi/linux/gfs2_ondisk.h | 25 +++++++++++++++++++++----
 7 files changed, 42 insertions(+), 19 deletions(-)

diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index 1f6c9c3..79cd4a9 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -358,7 +358,7 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
 	ip->i_inode.i_ctime.tv_nsec = be32_to_cpu(str->di_ctime_nsec);
 
 	ip->i_goal = be64_to_cpu(str->di_goal_meta);
-	ip->i_generation = be64_to_cpu(str->di_generation);
+	ip->i_inode.i_generation = be32_to_cpu(str->di_gen2);
 
 	ip->i_diskflags = be32_to_cpu(str->di_flags);
 	ip->i_eattr = be64_to_cpu(str->di_eattr);
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 76c9c77..8ca88b9 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -88,7 +88,13 @@ struct gfs2_rgrpd {
 	u32 rd_reserved;                /* number of blocks reserved */
 	u32 rd_free_clone;
 	u32 rd_dinodes;
-	u64 rd_igeneration;
+	union {
+		u64 rd_igeneration;
+		struct {
+			u32 rd_igen1;
+			u32 rd_igen2;
+		};
+	};
 	struct gfs2_bitmap *rd_bits;
 	struct gfs2_sbd *rd_sbd;
 	struct gfs2_rgrp_lvb *rd_rgl;
@@ -385,7 +391,6 @@ struct gfs2_inode {
 	struct inode i_inode;
 	u64 i_no_addr;
 	u64 i_no_formal_ino;
-	u64 i_generation;
 	u64 i_eattr;
 	unsigned long i_flags;		/* GIF_... */
 	struct gfs2_glock *i_gl; /* Move into i_gh? */
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 063fdfc..cc815ab 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -394,8 +394,9 @@ static int alloc_dinode(struct gfs2_inode *ip, u32 flags, unsigned *dblocks)
 	if (error)
 		goto out_ipreserv;
 
-	error = gfs2_alloc_blocks(ip, &ip->i_no_addr, dblocks, 1, &ip->i_generation);
-	ip->i_no_formal_ino = ip->i_generation;
+	error = gfs2_alloc_blocks(ip, &ip->i_no_addr, dblocks, 1,
+				  &ip->i_inode.i_generation);
+	ip->i_no_formal_ino = ip->i_inode.i_generation;
 	ip->i_inode.i_ino = ip->i_no_addr;
 	ip->i_goal = ip->i_no_addr;
 
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 475985d..34c42a8 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -1062,7 +1062,7 @@ static void gfs2_rgrp_in(struct gfs2_rgrpd *rgd, const void *buf)
 	rgd->rd_flags |= rg_flags;
 	rgd->rd_free = be32_to_cpu(str->rg_free);
 	rgd->rd_dinodes = be32_to_cpu(str->rg_dinodes);
-	rgd->rd_igeneration = be64_to_cpu(str->rg_igeneration);
+	rgd->rd_igen2 = be32_to_cpu(str->rg_igen2);
 }
 
 static void gfs2_rgrp_out(struct gfs2_rgrpd *rgd, void *buf)
@@ -1073,7 +1073,7 @@ static void gfs2_rgrp_out(struct gfs2_rgrpd *rgd, void *buf)
 	str->rg_free = cpu_to_be32(rgd->rd_free);
 	str->rg_dinodes = cpu_to_be32(rgd->rd_dinodes);
 	str->__pad = cpu_to_be32(0);
-	str->rg_igeneration = cpu_to_be64(rgd->rd_igeneration);
+	str->rg_igen2 = cpu_to_be64(rgd->rd_igen2);
 	memset(&str->rg_reserved, 0, sizeof(str->rg_reserved));
 }
 
@@ -1084,7 +1084,7 @@ static int gfs2_rgrp_lvb_valid(struct gfs2_rgrpd *rgd)
 
 	if (rgl->rl_flags != str->rg_flags || rgl->rl_free != str->rg_free ||
 	    rgl->rl_dinodes != str->rg_dinodes ||
-	    rgl->rl_igeneration != str->rg_igeneration)
+	    rgl->rl_igen2 != str->rg_igen2)
 		return 0;
 	return 1;
 }
@@ -1097,7 +1097,7 @@ static void gfs2_rgrp_ondisk2lvb(struct gfs2_rgrp_lvb *rgl, const void *buf)
 	rgl->rl_flags = str->rg_flags;
 	rgl->rl_free = str->rg_free;
 	rgl->rl_dinodes = str->rg_dinodes;
-	rgl->rl_igeneration = str->rg_igeneration;
+	rgl->rl_igen2 = str->rg_igen2;
 	rgl->__pad = 0UL;
 }
 
@@ -1229,7 +1229,7 @@ static int update_rgrp_lvb(struct gfs2_rgrpd *rgd)
 	rgd->rd_free = be32_to_cpu(rgd->rd_rgl->rl_free);
 	rgd->rd_free_clone = rgd->rd_free;
 	rgd->rd_dinodes = be32_to_cpu(rgd->rd_rgl->rl_dinodes);
-	rgd->rd_igeneration = be64_to_cpu(rgd->rd_rgl->rl_igeneration);
+	rgd->rd_igen2 = be64_to_cpu(rgd->rd_rgl->rl_igen2);
 	return 0;
 }
 
@@ -2334,7 +2334,7 @@ static void gfs2_set_alloc_start(struct gfs2_rbm *rbm,
  */
 
 int gfs2_alloc_blocks(struct gfs2_inode *ip, u64 *bn, unsigned int *nblocks,
-		      bool dinode, u64 *generation)
+		      bool dinode, u32 *generation)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	struct buffer_head *dibh;
@@ -2390,9 +2390,9 @@ int gfs2_alloc_blocks(struct gfs2_inode *ip, u64 *bn, unsigned int *nblocks,
 	rbm.rgd->rd_free -= *nblocks;
 	if (dinode) {
 		rbm.rgd->rd_dinodes++;
-		*generation = rbm.rgd->rd_igeneration++;
+		*generation = rbm.rgd->rd_igen2++;
 		if (*generation == 0)
-			*generation = rbm.rgd->rd_igeneration++;
+			*generation = rbm.rgd->rd_igen2++;
 	}
 
 	gfs2_trans_add_meta(rbm.rgd->rd_gl, rbm.rgd->rd_bits[0].bi_bh);
diff --git a/fs/gfs2/rgrp.h b/fs/gfs2/rgrp.h
index c0ab33f..71c1a8e 100644
--- a/fs/gfs2/rgrp.h
+++ b/fs/gfs2/rgrp.h
@@ -47,7 +47,7 @@ extern int gfs2_inplace_reserve(struct gfs2_inode *ip,
 extern void gfs2_inplace_release(struct gfs2_inode *ip);
 
 extern int gfs2_alloc_blocks(struct gfs2_inode *ip, u64 *bn, unsigned int *n,
-			     bool dinode, u64 *generation);
+			     bool dinode, u32 *generation);
 
 extern int gfs2_rs_alloc(struct gfs2_inode *ip);
 extern void gfs2_rs_deltree(struct gfs2_blkreserv *rs);
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 894fb01..928be2f 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -714,7 +714,7 @@ void gfs2_dinode_out(const struct gfs2_inode *ip, void *buf)
 
 	str->di_goal_meta = cpu_to_be64(ip->i_goal);
 	str->di_goal_data = cpu_to_be64(ip->i_goal);
-	str->di_generation = cpu_to_be64(ip->i_generation);
+	str->di_gen2 = cpu_to_be64(ip->i_inode.i_generation);
 
 	str->di_flags = cpu_to_be32(ip->i_diskflags);
 	str->di_height = cpu_to_be16(ip->i_height);
diff --git a/include/uapi/linux/gfs2_ondisk.h b/include/uapi/linux/gfs2_ondisk.h
index 1a763ea..bef244e 100644
--- a/include/uapi/linux/gfs2_ondisk.h
+++ b/include/uapi/linux/gfs2_ondisk.h
@@ -175,7 +175,13 @@ struct gfs2_rgrp_lvb {
 	__be32 rl_flags;
 	__be32 rl_free;
 	__be32 rl_dinodes;
-	__be64 rl_igeneration;
+	union {
+		__be64 rl_igeneration;
+		struct {
+			__be32 rl_igen1;
+			__be32 rl_igen2;
+		};
+	};
 	__be32 rl_unlinked;
 	__be32 __pad;
 };
@@ -187,7 +193,13 @@ struct gfs2_rgrp {
 	__be32 rg_free;
 	__be32 rg_dinodes;
 	__be32 __pad;
-	__be64 rg_igeneration;
+	union {
+		__be64 rg_igeneration;
+		struct {
+			__be32 rg_igen1;
+			__be32 rg_igen2;
+		};
+	};
 
 	__u8 rg_reserved[80]; /* Several fields from gfs1 now reserved */
 };
@@ -268,8 +280,13 @@ struct gfs2_dinode {
 	 */
 	__be64 di_goal_meta;	/* rgrp to alloc from next */
 	__be64 di_goal_data;	/* data block goal */
-	__be64 di_generation;	/* generation number for NFS */
-
+	union {
+		__be64 di_generation;	/* generation number for NFS */
+		struct {
+			__be32 di_gen1;
+			__be32 di_gen2;
+		};
+	};
 	__be32 di_flags;	/* GFS2_DIF_... */
 	__be32 di_payload_format;  /* GFS2_FORMAT_... */
 	__u16 __pad1;	/* Was ditype in gfs1 */
-- 
2.4.3