[PATCH] inode_diet: Replace inode.u.generic_ip with inode.i_private

The following patches reduce the size of the VFS inode structure by 28 bytes
on a UP x86.  (It would be more on an x86_64 system).  This is a 10% reduction
in the inode size on a UP kernel that is configured in a production mode
(i.e., with no spinlock or other debugging functions enabled; if you want to
save memory taken up by in-core inodes, the first thing you should do is
disable the debugging options; they are responsible for a huge amount of bloat
in the VFS inode structure).

This patch:

The filesystem or device-specific pointer in the inode is inside a union,
which is pretty pointless given that all 30+ users of this field have been
using the void pointer.  Get rid of the union and rename it to i_private, with
a comment to explain who is allowed to use the void pointer.  This is just a
cleanup, but it allows us to reuse the union 'u' for something something where
the union will actually be used.

[judith@osdl.org: powerpc build fix]
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Judith Lebzelter <judith@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

13 files changed, 38 insertions, 38 deletions

diff --git a/fs/autofs/inode.c b/fs/autofs/inode.c
index c81d6b8..d39d2ac 100644
--- a/fs/autofs/inode.c
+++ b/fs/autofs/inode.c
@@ -241,7 +241,7 @@ static void autofs_read_inode(struct inode *inode)
 		
 		inode->i_op = &autofs_symlink_inode_operations;
 		sl = &sbi->symlink[n];
-		inode->u.generic_ip = sl;
+		inode->i_private = sl;
 		inode->i_mode = S_IFLNK | S_IRWXUGO;
 		inode->i_mtime.tv_sec = inode->i_ctime.tv_sec = sl->mtime;
 		inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
diff --git a/fs/autofs/symlink.c b/fs/autofs/symlink.c
index 52e8772..c74f2eb 100644
--- a/fs/autofs/symlink.c
+++ b/fs/autofs/symlink.c
@@ -15,7 +15,7 @@
 /* Nothing to release.. */
 static void *autofs_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
-	char *s=((struct autofs_symlink *)dentry->d_inode->u.generic_ip)->data;
+	char *s=((struct autofs_symlink *)dentry->d_inode->i_private)->data;
 	nd_set_link(nd, s);
 	return NULL;
 }
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 34ebbc1..6759b98 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -517,7 +517,7 @@ static struct inode *bm_get_inode(struct super_block *sb, int mode)
 
 static void bm_clear_inode(struct inode *inode)
 {
-	kfree(inode->u.generic_ip);
+	kfree(inode->i_private);
 }
 
 static void kill_node(Node *e)
@@ -545,7 +545,7 @@ static void kill_node(Node *e)
 static ssize_t
 bm_entry_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
 {
-	Node *e = file->f_dentry->d_inode->u.generic_ip;
+	Node *e = file->f_dentry->d_inode->i_private;
 	loff_t pos = *ppos;
 	ssize_t res;
 	char *page;
@@ -579,7 +579,7 @@ static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
 				size_t count, loff_t *ppos)
 {
 	struct dentry *root;
-	Node *e = file->f_dentry->d_inode->u.generic_ip;
+	Node *e = file->f_dentry->d_inode->i_private;
 	int res = parse_command(buffer, count);
 
 	switch (res) {
@@ -646,7 +646,7 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
 	}
 
 	e->dentry = dget(dentry);
-	inode->u.generic_ip = e;
+	inode->i_private = e;
 	inode->i_fop = &bm_entry_operations;
 
 	d_instantiate(dentry, inode);
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index e4b4305..bf3901a 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -32,8 +32,8 @@ static ssize_t default_write_file(struct file *file, const char __user *buf,
 
 static int default_open(struct inode *inode, struct file *file)
 {
-	if (inode->u.generic_ip)
-		file->private_data = inode->u.generic_ip;
+	if (inode->i_private)
+		file->private_data = inode->i_private;
 
 	return 0;
 }
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 3ca268d..717f4821 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -168,7 +168,7 @@ static int debugfs_create_by_name(const char *name, mode_t mode,
  *          directory dentry if set.  If this paramater is NULL, then the
  *          file will be created in the root of the debugfs filesystem.
  * @data: a pointer to something that the caller will want to get to later
- *        on.  The inode.u.generic_ip pointer will point to this value on
+ *        on.  The inode.i_private pointer will point to this value on
  *        the open() call.
  * @fops: a pointer to a struct file_operations that should be used for
  *        this file.
@@ -209,7 +209,7 @@ struct dentry *debugfs_create_file(const char *name, mode_t mode,
 
 	if (dentry->d_inode) {
 		if (data)
-			dentry->d_inode->u.generic_ip = data;
+			dentry->d_inode->i_private = data;
 		if (fops)
 			dentry->d_inode->i_fop = fops;
 	}
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index f7aef5b..5bf06a1 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -177,7 +177,7 @@ int devpts_pty_new(struct tty_struct *tty)
 	inode->i_gid = config.setgid ? config.gid : current->fsgid;
 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 	init_special_inode(inode, S_IFCHR|config.mode, device);
-	inode->u.generic_ip = tty;
+	inode->i_private = tty;
 
 	dentry = get_node(number);
 	if (!IS_ERR(dentry) && !dentry->d_inode)
@@ -196,7 +196,7 @@ struct tty_struct *devpts_get_tty(int number)
 	tty = NULL;
 	if (!IS_ERR(dentry)) {
 		if (dentry->d_inode)
-			tty = dentry->d_inode->u.generic_ip;
+			tty = dentry->d_inode->i_private;
 		dput(dentry);
 	}
 
diff --git a/fs/freevxfs/vxfs.h b/fs/freevxfs/vxfs.h
index d35979a..c8a9265 100644
--- a/fs/freevxfs/vxfs.h
+++ b/fs/freevxfs/vxfs.h
@@ -252,7 +252,7 @@ enum {
  * Get filesystem private data from VFS inode.
  */
 #define VXFS_INO(ip) \
-	((struct vxfs_inode_info *)(ip)->u.generic_ip)
+	((struct vxfs_inode_info *)(ip)->i_private)
 
 /*
  * Get filesystem private data from VFS superblock.
diff --git a/fs/freevxfs/vxfs_inode.c b/fs/freevxfs/vxfs_inode.c
index ca6a397..32a82ed 100644
--- a/fs/freevxfs/vxfs_inode.c
+++ b/fs/freevxfs/vxfs_inode.c
@@ -243,7 +243,7 @@ vxfs_iinit(struct inode *ip, struct vxfs_inode_info *vip)
 	ip->i_blocks = vip->vii_blocks;
 	ip->i_generation = vip->vii_gen;
 
-	ip->u.generic_ip = (void *)vip;
+	ip->i_private = vip;
 	
 }
 
@@ -338,5 +338,5 @@ vxfs_read_inode(struct inode *ip)
 void
 vxfs_clear_inode(struct inode *ip)
 {
-	kmem_cache_free(vxfs_inode_cachep, ip->u.generic_ip);
+	kmem_cache_free(vxfs_inode_cachep, ip->i_private);
 }
diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index 46fe60b..79ec1f2 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -23,7 +23,7 @@ static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
 {
 	struct fuse_conn *fc;
 	mutex_lock(&fuse_mutex);
-	fc = file->f_dentry->d_inode->u.generic_ip;
+	fc = file->f_dentry->d_inode->i_private;
 	if (fc)
 		fc = fuse_conn_get(fc);
 	mutex_unlock(&fuse_mutex);
@@ -98,7 +98,7 @@ static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
 		inode->i_op = iop;
 	inode->i_fop = fop;
 	inode->i_nlink = nlink;
-	inode->u.generic_ip = fc;
+	inode->i_private = fc;
 	d_add(dentry, inode);
 	return dentry;
 }
@@ -150,7 +150,7 @@ void fuse_ctl_remove_conn(struct fuse_conn *fc)
 
 	for (i = fc->ctl_ndents - 1; i >= 0; i--) {
 		struct dentry *dentry = fc->ctl_dentry[i];
-		dentry->d_inode->u.generic_ip = NULL;
+		dentry->d_inode->i_private = NULL;
 		d_drop(dentry);
 		dput(dentry);
 	}
diff --git a/fs/inode.c b/fs/inode.c
index 0bf9f04..77e2547 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -163,7 +163,7 @@ static struct inode *alloc_inode(struct super_block *sb)
 				bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
 			mapping->backing_dev_info = bdi;
 		}
-		memset(&inode->u, 0, sizeof(inode->u));
+		inode->i_private = 0;
 		inode->i_mapping = mapping;
 	}
 	return inode;
diff --git a/fs/jffs/inode-v23.c b/fs/jffs/inode-v23.c
index b59553d..7358ef8 100644
--- a/fs/jffs/inode-v23.c
+++ b/fs/jffs/inode-v23.c
@@ -369,7 +369,7 @@ jffs_new_inode(const struct inode * dir, struct jffs_raw_inode *raw_inode,
 
 	f = jffs_find_file(c, raw_inode->ino);
 
-	inode->u.generic_ip = (void *)f;
+	inode->i_private = (void *)f;
 	insert_inode_hash(inode);
 
 	return inode;
@@ -442,7 +442,7 @@ jffs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	});
 
 	result = -ENOTDIR;
-	if (!(old_dir_f = (struct jffs_file *)old_dir->u.generic_ip)) {
+	if (!(old_dir_f = old_dir->i_private)) {
 		D(printk("jffs_rename(): Old dir invalid.\n"));
 		goto jffs_rename_end;
 	}
@@ -456,7 +456,7 @@ jffs_rename(struct inode *old_dir, struct dentry *old_dentry,
 
 	/* Find the new directory.  */
 	result = -ENOTDIR;
-	if (!(new_dir_f = (struct jffs_file *)new_dir->u.generic_ip)) {
+	if (!(new_dir_f = new_dir->i_private)) {
 		D(printk("jffs_rename(): New dir invalid.\n"));
 		goto jffs_rename_end;
 	}
@@ -593,7 +593,7 @@ jffs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 		}
 		else {
 			ddino = ((struct jffs_file *)
-				 inode->u.generic_ip)->pino;
+				 inode->i_private)->pino;
 		}
 		D3(printk("jffs_readdir(): \"..\" %u\n", ddino));
 		if (filldir(dirent, "..", 2, filp->f_pos, ddino, DT_DIR) < 0) {
@@ -604,7 +604,7 @@ jffs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 		}
 		filp->f_pos++;
 	}
-	f = ((struct jffs_file *)inode->u.generic_ip)->children;
+	f = ((struct jffs_file *)inode->i_private)->children;
 
 	j = 2;
 	while(f && (f->deleted || j++ < filp->f_pos )) {
@@ -668,7 +668,7 @@ jffs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 	}
 
 	r = -EACCES;
-	if (!(d = (struct jffs_file *)dir->u.generic_ip)) {
+	if (!(d = (struct jffs_file *)dir->i_private)) {
 		D(printk("jffs_lookup(): No such inode! (%lu)\n",
 			 dir->i_ino));
 		goto jffs_lookup_end;
@@ -739,7 +739,7 @@ jffs_do_readpage_nolock(struct file *file, struct page *page)
 	unsigned long read_len;
 	int result;
 	struct inode *inode = (struct inode*)page->mapping->host;
-	struct jffs_file *f = (struct jffs_file *)inode->u.generic_ip;
+	struct jffs_file *f = (struct jffs_file *)inode->i_private;
 	struct jffs_control *c = (struct jffs_control *)inode->i_sb->s_fs_info;
 	int r;
 	loff_t offset;
@@ -828,7 +828,7 @@ jffs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 	});
 
 	lock_kernel();
-	dir_f = (struct jffs_file *)dir->u.generic_ip;
+	dir_f = dir->i_private;
 
 	ASSERT(if (!dir_f) {
 		printk(KERN_ERR "jffs_mkdir(): No reference to a "
@@ -972,7 +972,7 @@ jffs_remove(struct inode *dir, struct dentry *dentry, int type)
 		kfree(_name);
 	});
 
-	dir_f = (struct jffs_file *) dir->u.generic_ip;
+	dir_f = dir->i_private;
 	c = dir_f->c;
 
 	result = -ENOENT;
@@ -1082,7 +1082,7 @@ jffs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t rdev)
 	if (!old_valid_dev(rdev))
 		return -EINVAL;
 	lock_kernel();
-	dir_f = (struct jffs_file *)dir->u.generic_ip;
+	dir_f = dir->i_private;
 	c = dir_f->c;
 
 	D3(printk (KERN_NOTICE "mknod(): down biglock\n"));
@@ -1186,7 +1186,7 @@ jffs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
 		kfree(_symname);
 	});
 
-	dir_f = (struct jffs_file *)dir->u.generic_ip;
+	dir_f = dir->i_private;
 	ASSERT(if (!dir_f) {
 		printk(KERN_ERR "jffs_symlink(): No reference to a "
 		       "jffs_file struct in inode.\n");
@@ -1289,7 +1289,7 @@ jffs_create(struct inode *dir, struct dentry *dentry, int mode,
 		kfree(s);
 	});
 
-	dir_f = (struct jffs_file *)dir->u.generic_ip;
+	dir_f = dir->i_private;
 	ASSERT(if (!dir_f) {
 		printk(KERN_ERR "jffs_create(): No reference to a "
 		       "jffs_file struct in inode.\n");
@@ -1403,9 +1403,9 @@ jffs_file_write(struct file *filp, const char *buf, size_t count,
 		goto out_isem;
 	}
 
-	if (!(f = (struct jffs_file *)inode->u.generic_ip)) {
-		D(printk("jffs_file_write(): inode->u.generic_ip = 0x%p\n",
-				inode->u.generic_ip));
+	if (!(f = inode->i_private)) {
+		D(printk("jffs_file_write(): inode->i_private = 0x%p\n",
+				inode->i_private));
 		goto out_isem;
 	}
 
@@ -1693,7 +1693,7 @@ jffs_read_inode(struct inode *inode)
 		mutex_unlock(&c->fmc->biglock);
 		return;
 	}
-	inode->u.generic_ip = (void *)f;
+	inode->i_private = f;
 	inode->i_mode = f->mode;
 	inode->i_nlink = f->nlink;
 	inode->i_uid = f->uid;
@@ -1748,7 +1748,7 @@ jffs_delete_inode(struct inode *inode)
 	lock_kernel();
 	inode->i_size = 0;
 	inode->i_blocks = 0;
-	inode->u.generic_ip = NULL;
+	inode->i_private = NULL;
 	clear_inode(inode);
 	if (inode->i_nlink == 0) {
 		c = (struct jffs_control *) inode->i_sb->s_fs_info;
diff --git a/fs/libfs.c b/fs/libfs.c
index ac02ea6..2751793 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -547,7 +547,7 @@ int simple_attr_open(struct inode *inode, struct file *file,
 
 	attr->get = get;
 	attr->set = set;
-	attr->data = inode->u.generic_ip;
+	attr->data = inode->i_private;
 	attr->fmt = fmt;
 	mutex_init(&attr->mutex);
 
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index de88706..8801e41 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2052,7 +2052,7 @@ static int ocfs2_dlm_debug_open(struct inode *inode, struct file *file)
 		mlog_errno(ret);
 		goto out;
 	}
-	osb = (struct ocfs2_super *) inode->u.generic_ip;
+	osb = inode->i_private;
 	ocfs2_get_dlm_debug(osb->osb_dlm_debug);
 	priv->p_dlm_debug = osb->osb_dlm_debug;
 	INIT_LIST_HEAD(&priv->p_iter_res.l_debug_list);