[GFS2] Shrink gfs2_inode (8) - i_vn

This shrinks the size of the gfs2_inode by 8 bytes by
replacing the version counter with a one bit valid/invalid
flag.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/glops.c

@@ -305,8 +305,9 @@ static void inode_go_inval(struct gfs2_glock *gl, int flags)
 	int data = (flags & DIO_DATA);
 
 	if (meta) {
+		struct gfs2_inode *ip = gl->gl_object;
 		gfs2_meta_inval(gl);
-		gl->gl_vn++;
+		set_bit(GIF_INVALID, &ip->i_flags);
 	}
 	if (data)
 		gfs2_page_inval(gl);
@@ -351,7 +352,7 @@ static int inode_go_lock(struct gfs2_holder *gh)
 	if (!ip)
 		return 0;
 
-	if (ip->i_vn != gl->gl_vn) {
+	if (test_bit(GIF_INVALID, &ip->i_flags)) {
 		error = gfs2_inode_refresh(ip);
 		if (error)
 			return error;

fs/gfs2/incore.h

@@ -217,6 +217,7 @@ struct gfs2_alloc {
 };
 
 enum {
+	GIF_INVALID		= 0,
 	GIF_QD_LOCKED		= 1,
 	GIF_PAGED		= 2,
 	GIF_SW_PAGED		= 3,
@@ -228,7 +229,6 @@ struct gfs2_inode {
 
 	unsigned long i_flags;		/* GIF_... */
 
-	u64 i_vn;
 	struct gfs2_dinode_host i_di; /* To be replaced by ref to block */
 
 	struct gfs2_glock *i_gl; /* Move into i_gh? */

fs/gfs2/inode.c

@@ -145,7 +145,7 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, struct gfs2_inum_host *i
 		if (unlikely(error))
 			goto fail_put;
 
-		ip->i_vn = ip->i_gl->gl_vn - 1;
+		set_bit(GIF_INVALID, &ip->i_flags);
 		error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh);
 		if (unlikely(error))
 			goto fail_iopen;
@@ -242,7 +242,7 @@ int gfs2_inode_refresh(struct gfs2_inode *ip)
 
 	error = gfs2_dinode_in(ip, dibh->b_data);
 	brelse(dibh);
-	ip->i_vn = ip->i_gl->gl_vn;
+	clear_bit(GIF_INVALID, &ip->i_flags);
 
 	return error;
 }

fs/gfs2/ops_inode.c

@@ -844,7 +844,7 @@ static int gfs2_permission(struct inode *inode, int mask, struct nameidata *nd)
 	struct gfs2_holder i_gh;
 	int error;
 
-	if (ip->i_vn == ip->i_gl->gl_vn)
+	if (!test_bit(GIF_INVALID, &ip->i_flags))
 		return generic_permission(inode, mask, gfs2_check_acl);
 
 	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);