[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.

[[email protected]: powerpc build fix]
Signed-off-by: "Theodore Ts'o" <[email protected]>
Signed-off-by: Judith Lebzelter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

arch/powerpc/platforms/cell/spufs/inode.c

@@ -120,7 +120,7 @@ spufs_new_file(struct super_block *sb, struct dentry *dentry,
 	ret = 0;
 	inode->i_op = &spufs_file_iops;
 	inode->i_fop = fops;
-	inode->u.generic_ip = SPUFS_I(inode)->i_ctx = get_spu_context(ctx);
+	inode->i_private = SPUFS_I(inode)->i_ctx = get_spu_context(ctx);
 	d_add(dentry, inode);
 out:
 	return ret;

arch/powerpc/platforms/pseries/hvCall_inst.c

@@ -85,7 +85,7 @@ static int hcall_inst_seq_open(struct inode *inode, struct file *file)
 
 	rc = seq_open(file, &hcall_inst_seq_ops);
 	seq = file->private_data;
-	seq->private = file->f_dentry->d_inode->u.generic_ip;
+	seq->private = file->f_dentry->d_inode->i_private;
 
 	return rc;
 }

arch/s390/hypfs/inode.c

@@ -104,13 +104,13 @@ static struct inode *hypfs_make_inode(struct super_block *sb, int mode)
 
 static void hypfs_drop_inode(struct inode *inode)
 {
-	kfree(inode->u.generic_ip);
+	kfree(inode->i_private);
 	generic_delete_inode(inode);
 }
 
 static int hypfs_open(struct inode *inode, struct file *filp)
 {
-	char *data = filp->f_dentry->d_inode->u.generic_ip;
+	char *data = filp->f_dentry->d_inode->i_private;
 	struct hypfs_sb_info *fs_info;
 
 	if (filp->f_mode & FMODE_WRITE) {
@@ -352,7 +352,7 @@ static struct dentry *hypfs_create_file(struct super_block *sb,
 		parent->d_inode->i_nlink++;
 	} else
 		BUG();
-	inode->u.generic_ip = data;
+	inode->i_private = data;
 	d_instantiate(dentry, inode);
 	dget(dentry);
 	return dentry;

arch/s390/kernel/debug.c

@@ -603,7 +603,7 @@ debug_open(struct inode *inode, struct file *file)
 	debug_info_t *debug_info, *debug_info_snapshot;
 
 	down(&debug_lock);
-	debug_info = (struct debug_info*)file->f_dentry->d_inode->u.generic_ip;
+	debug_info = file->f_dentry->d_inode->i_private;
 	/* find debug view */
 	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
 		if (!debug_info->views[i])

block/blktrace.c

@@ -217,7 +217,7 @@ static int blk_trace_remove(request_queue_t *q)
 
 static int blk_dropped_open(struct inode *inode, struct file *filp)
 {
-	filp->private_data = inode->u.generic_ip;
+	filp->private_data = inode->i_private;
 
 	return 0;
 }

drivers/i2c/chips/tps65010.c

@@ -305,7 +305,7 @@ static int dbg_show(struct seq_file *s, void *_)
 
 static int dbg_tps_open(struct inode *inode, struct file *file)
 {
-	return single_open(file, dbg_show, inode->u.generic_ip);
+	return single_open(file, dbg_show, inode->i_private);
 }
 
 static struct file_operations debug_fops = {

drivers/infiniband/hw/ipath/ipath_fs.c

@@ -64,7 +64,7 @@ static int ipathfs_mknod(struct inode *dir, struct dentry *dentry,
 	inode->i_blksize = PAGE_CACHE_SIZE;
 	inode->i_blocks = 0;
 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
-	inode->u.generic_ip = data;
+	inode->i_private = data;
 	if ((mode & S_IFMT) == S_IFDIR) {
 		inode->i_op = &simple_dir_inode_operations;
 		inode->i_nlink++;
@@ -119,7 +119,7 @@ static ssize_t atomic_counters_read(struct file *file, char __user *buf,
 	u16 i;
 	struct ipath_devdata *dd;
 
-	dd = file->f_dentry->d_inode->u.generic_ip;
+	dd = file->f_dentry->d_inode->i_private;
 
 	for (i = 0; i < NUM_COUNTERS; i++)
 		counters[i] = ipath_snap_cntr(dd, i);
@@ -139,7 +139,7 @@ static ssize_t atomic_node_info_read(struct file *file, char __user *buf,
 	struct ipath_devdata *dd;
 	u64 guid;
 
-	dd = file->f_dentry->d_inode->u.generic_ip;
+	dd = file->f_dentry->d_inode->i_private;
 
 	guid = be64_to_cpu(dd->ipath_guid);
 
@@ -178,7 +178,7 @@ static ssize_t atomic_port_info_read(struct file *file, char __user *buf,
 	u32 tmp, tmp2;
 	struct ipath_devdata *dd;
 
-	dd = file->f_dentry->d_inode->u.generic_ip;
+	dd = file->f_dentry->d_inode->i_private;
 
 	/* so we only initialize non-zero fields. */
 	memset(portinfo, 0, sizeof portinfo);
@@ -325,7 +325,7 @@ static ssize_t flash_read(struct file *file, char __user *buf,
 		goto bail;
 	}
 
-	dd = file->f_dentry->d_inode->u.generic_ip;
+	dd = file->f_dentry->d_inode->i_private;
 	if (ipath_eeprom_read(dd, pos, tmp, count)) {
 		ipath_dev_err(dd, "failed to read from flash\n");
 		ret = -ENXIO;
@@ -381,7 +381,7 @@ static ssize_t flash_write(struct file *file, const char __user *buf,
 		goto bail_tmp;
 	}
 
-	dd = file->f_dentry->d_inode->u.generic_ip;
+	dd = file->f_dentry->d_inode->i_private;
 	if (ipath_eeprom_write(dd, pos, tmp, count)) {
 		ret = -ENXIO;
 		ipath_dev_err(dd, "failed to write to flash\n");

drivers/infiniband/ulp/ipoib/ipoib_fs.c

@@ -141,7 +141,7 @@ static int ipoib_mcg_open(struct inode *inode, struct file *file)
 		return ret;
 
 	seq = file->private_data;
-	seq->private = inode->u.generic_ip;
+	seq->private = inode->i_private;
 
 	return 0;
 }
@@ -247,7 +247,7 @@ static int ipoib_path_open(struct inode *inode, struct file *file)
 		return ret;
 
 	seq = file->private_data;
-	seq->private = inode->u.generic_ip;
+	seq->private = inode->i_private;
 
 	return 0;
 }

drivers/misc/ibmasm/ibmasmfs.c

@@ -175,7 +175,7 @@ static struct dentry *ibmasmfs_create_file (struct super_block *sb,
 	}
 
 	inode->i_fop = fops;
-	inode->u.generic_ip = data;
+	inode->i_private = data;
 
 	d_add(dentry, inode);
 	return dentry;
@@ -244,15 +244,15 @@ static int command_file_open(struct inode *inode, struct file *file)
 {
 	struct ibmasmfs_command_data *command_data;
 
-	if (!inode->u.generic_ip)
+	if (!inode->i_private)
 		return -ENODEV;
 
 	command_data = kmalloc(sizeof(struct ibmasmfs_command_data), GFP_KERNEL);
 	if (!command_data)
 		return -ENOMEM;
 
 	command_data->command = NULL;
-	command_data->sp = inode->u.generic_ip;
+	command_data->sp = inode->i_private;
 	file->private_data = command_data;
 	return 0;
 }
@@ -351,10 +351,10 @@ static int event_file_open(struct inode *inode, struct file *file)
 	struct ibmasmfs_event_data *event_data;
 	struct service_processor *sp; 
 
-	if (!inode->u.generic_ip)
+	if (!inode->i_private)
 		return -ENODEV;
 
-	sp = inode->u.generic_ip;
+	sp = inode->i_private;
 
 	event_data = kmalloc(sizeof(struct ibmasmfs_event_data), GFP_KERNEL);
 	if (!event_data)
@@ -439,14 +439,14 @@ static int r_heartbeat_file_open(struct inode *inode, struct file *file)
 {
 	struct ibmasmfs_heartbeat_data *rhbeat;
 
-	if (!inode->u.generic_ip)
+	if (!inode->i_private)
 		return -ENODEV;
 
 	rhbeat = kmalloc(sizeof(struct ibmasmfs_heartbeat_data), GFP_KERNEL);
 	if (!rhbeat)
 		return -ENOMEM;
 
-	rhbeat->sp = (struct service_processor *)inode->u.generic_ip;
+	rhbeat->sp = inode->i_private;
 	rhbeat->active = 0;
 	ibmasm_init_reverse_heartbeat(rhbeat->sp, &rhbeat->heartbeat);
 	file->private_data = rhbeat;
@@ -508,7 +508,7 @@ static ssize_t r_heartbeat_file_write(struct file *file, const char __user *buf,
 
 static int remote_settings_file_open(struct inode *inode, struct file *file)
 {
-	file->private_data = inode->u.generic_ip;
+	file->private_data = inode->i_private;
 	return 0;
 }
 

drivers/net/irda/vlsi_ir.h

@@ -58,7 +58,7 @@ typedef void irqreturn_t;
 
 /* PDE() introduced in 2.5.4 */
 #ifdef CONFIG_PROC_FS
-#define PDE(inode) ((inode)->u.generic_ip)
+#define PDE(inode) ((inode)->i_private)
 #endif
 
 /* irda crc16 calculation exported in 2.5.42 */

drivers/net/wireless/bcm43xx/bcm43xx_debugfs.c

@@ -54,7 +54,7 @@ static ssize_t write_file_dummy(struct file *file, const char __user *buf,
 
 static int open_file_generic(struct inode *inode, struct file *file)
 {
-	file->private_data = inode->u.generic_ip;
+	file->private_data = inode->i_private;
 	return 0;
 }
 

drivers/oprofile/oprofilefs.c

@@ -110,8 +110,8 @@ static ssize_t ulong_write_file(struct file * file, char const __user * buf, siz
 
 static int default_open(struct inode * inode, struct file * filp)
 {
-	if (inode->u.generic_ip)
-		filp->private_data = inode->u.generic_ip;
+	if (inode->i_private)
+		filp->private_data = inode->i_private;
 	return 0;
 }
 
@@ -158,7 +158,7 @@ int oprofilefs_create_ulong(struct super_block * sb, struct dentry * root,
 	if (!d)
 		return -EFAULT;
 
-	d->d_inode->u.generic_ip = val;
+	d->d_inode->i_private = val;
 	return 0;
 }
 
@@ -171,7 +171,7 @@ int oprofilefs_create_ro_ulong(struct super_block * sb, struct dentry * root,
 	if (!d)
 		return -EFAULT;
 
-	d->d_inode->u.generic_ip = val;
+	d->d_inode->i_private = val;
 	return 0;
 }
 
@@ -197,7 +197,7 @@ int oprofilefs_create_ro_atomic(struct super_block * sb, struct dentry * root,
 	if (!d)
 		return -EFAULT;
 
-	d->d_inode->u.generic_ip = val;
+	d->d_inode->i_private = val;
 	return 0;
 }
 

drivers/pci/hotplug/cpqphp_sysfs.c

@@ -140,7 +140,7 @@ struct ctrl_dbg {
 
 static int open(struct inode *inode, struct file *file)
 {
-	struct controller *ctrl = inode->u.generic_ip;
+	struct controller *ctrl = inode->i_private;
 	struct ctrl_dbg *dbg;
 	int retval = -ENOMEM;
 

drivers/usb/core/devio.c

@@ -555,7 +555,7 @@ static int usbdev_open(struct inode *inode, struct file *file)
 	if (imajor(inode) == USB_DEVICE_MAJOR)
 		dev = usbdev_lookup_minor(iminor(inode));
 	if (!dev)
-		dev = inode->u.generic_ip;
+		dev = inode->i_private;
 	if (!dev) {
 		kfree(ps);
 		goto out;

drivers/usb/core/inode.c

@@ -402,8 +402,8 @@ static loff_t default_file_lseek (struct file *file, loff_t offset, int orig)
 
 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;
 }
@@ -509,7 +509,7 @@ static struct dentry *fs_create_file (const char *name, mode_t mode,
 	} else {
 		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;
 			dentry->d_inode->i_uid = uid;

drivers/usb/gadget/inode.c

@@ -844,7 +844,7 @@ ep_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
 static int
 ep_open (struct inode *inode, struct file *fd)
 {
-	struct ep_data		*data = inode->u.generic_ip;
+	struct ep_data		*data = inode->i_private;
 	int			value = -EBUSY;
 
 	if (down_interruptible (&data->lock) != 0)
@@ -1909,7 +1909,7 @@ dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
 static int
 dev_open (struct inode *inode, struct file *fd)
 {
-	struct dev_data		*dev = inode->u.generic_ip;
+	struct dev_data		*dev = inode->i_private;
 	int			value = -EBUSY;
 
 	if (dev->state == STATE_DEV_DISABLED) {
@@ -1970,7 +1970,7 @@ gadgetfs_make_inode (struct super_block *sb,
 		inode->i_blocks = 0;
 		inode->i_atime = inode->i_mtime = inode->i_ctime
 				= CURRENT_TIME;
-		inode->u.generic_ip = data;
+		inode->i_private = data;
 		inode->i_fop = fops;
 	}
 	return inode;

drivers/usb/host/isp116x-hcd.c

@@ -1204,7 +1204,7 @@ static int isp116x_show_dbg(struct seq_file *s, void *unused)
 
 static int isp116x_open_seq(struct inode *inode, struct file *file)
 {
-	return single_open(file, isp116x_show_dbg, inode->u.generic_ip);
+	return single_open(file, isp116x_show_dbg, inode->i_private);
 }
 
 static struct file_operations isp116x_debug_fops = {

drivers/usb/host/uhci-debug.c

@@ -428,7 +428,7 @@ struct uhci_debug {
 
 static int uhci_debug_open(struct inode *inode, struct file *file)
 {
-	struct uhci_hcd *uhci = inode->u.generic_ip;
+	struct uhci_hcd *uhci = inode->i_private;
 	struct uhci_debug *up;
 	int ret = -ENOMEM;
 	unsigned long flags;

drivers/usb/mon/mon_stat.c

@@ -28,7 +28,7 @@ static int mon_stat_open(struct inode *inode, struct file *file)
 	if ((sp = kmalloc(sizeof(struct snap), GFP_KERNEL)) == NULL)
 		return -ENOMEM;
 
-	mbus = inode->u.generic_ip;
+	mbus = inode->i_private;
 
 	sp->slen = snprintf(sp->str, STAT_BUF_SIZE,
 	    "nreaders %d events %u text_lost %u\n",

drivers/usb/mon/mon_text.c

@@ -238,7 +238,7 @@ static int mon_text_open(struct inode *inode, struct file *file)
 	int rc;
 
 	mutex_lock(&mon_lock);
-	mbus = inode->u.generic_ip;
+	mbus = inode->i_private;
 	ubus = mbus->u_bus;
 
 	rp = kzalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
@@ -401,7 +401,7 @@ static int mon_text_release(struct inode *inode, struct file *file)
 	struct mon_event_text *ep;
 
 	mutex_lock(&mon_lock);
-	mbus = inode->u.generic_ip;
+	mbus = inode->i_private;
 
 	if (mbus->nreaders <= 0) {
 		printk(KERN_ERR TAG ": consistency error on close\n");

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;

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;
 }