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![Nick Piggin](/assets/img/avatar_default.png)
RCU free the struct inode. This will allow: - Subsequent store-free path walking patch. The inode must be consulted for permissions when walking, so an RCU inode reference is a must. - sb_inode_list_lock to be moved inside i_lock because sb list walkers who want to take i_lock no longer need to take sb_inode_list_lock to walk the list in the first place. This will simplify and optimize locking. - Could remove some nested trylock loops in dcache code - Could potentially simplify things a bit in VM land. Do not need to take the page lock to follow page->mapping. The downsides of this is the performance cost of using RCU. In a simple creat/unlink microbenchmark, performance drops by about 10% due to inability to reuse cache-hot slab objects. As iterations increase and RCU freeing starts kicking over, this increases to about 20%. In cases where inode lifetimes are longer (ie. many inodes may be allocated during the average life span of a single inode), a lot of this cache reuse is not applicable, so the regression caused by this patch is smaller. The cache-hot regression could largely be avoided by using SLAB_DESTROY_BY_RCU, however this adds some complexity to list walking and store-free path walking, so I prefer to implement this at a later date, if it is shown to be a win in real situations. I haven't found a regression in any non-micro benchmark so I doubt it will be a problem. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
473 lines
9.7 KiB
C
473 lines
9.7 KiB
C
/* inode.c: /proc/openprom handling routines
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*
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* Copyright (C) 1996-1999 Jakub Jelinek (jakub@redhat.com)
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* Copyright (C) 1998 Eddie C. Dost (ecd@skynet.be)
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/seq_file.h>
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#include <linux/magic.h>
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#include <asm/openprom.h>
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#include <asm/oplib.h>
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#include <asm/prom.h>
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#include <asm/uaccess.h>
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static DEFINE_MUTEX(op_mutex);
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#define OPENPROM_ROOT_INO 0
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enum op_inode_type {
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op_inode_node,
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op_inode_prop,
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};
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union op_inode_data {
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struct device_node *node;
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struct property *prop;
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};
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struct op_inode_info {
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struct inode vfs_inode;
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enum op_inode_type type;
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union op_inode_data u;
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};
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static struct inode *openprom_iget(struct super_block *sb, ino_t ino);
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static inline struct op_inode_info *OP_I(struct inode *inode)
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{
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return container_of(inode, struct op_inode_info, vfs_inode);
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}
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static int is_string(unsigned char *p, int len)
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{
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int i;
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for (i = 0; i < len; i++) {
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unsigned char val = p[i];
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if ((i && !val) ||
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(val >= ' ' && val <= '~'))
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continue;
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return 0;
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}
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return 1;
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}
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static int property_show(struct seq_file *f, void *v)
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{
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struct property *prop = f->private;
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void *pval;
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int len;
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len = prop->length;
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pval = prop->value;
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if (is_string(pval, len)) {
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while (len > 0) {
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int n = strlen(pval);
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seq_printf(f, "%s", (char *) pval);
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/* Skip over the NULL byte too. */
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pval += n + 1;
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len -= n + 1;
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if (len > 0)
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seq_printf(f, " + ");
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}
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} else {
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if (len & 3) {
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while (len) {
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len--;
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if (len)
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seq_printf(f, "%02x.",
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*(unsigned char *) pval);
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else
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seq_printf(f, "%02x",
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*(unsigned char *) pval);
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pval++;
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}
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} else {
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while (len >= 4) {
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len -= 4;
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if (len)
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seq_printf(f, "%08x.",
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*(unsigned int *) pval);
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else
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seq_printf(f, "%08x",
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*(unsigned int *) pval);
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pval += 4;
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}
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}
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}
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seq_printf(f, "\n");
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return 0;
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}
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static void *property_start(struct seq_file *f, loff_t *pos)
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{
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if (*pos == 0)
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return pos;
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return NULL;
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}
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static void *property_next(struct seq_file *f, void *v, loff_t *pos)
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{
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(*pos)++;
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return NULL;
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}
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static void property_stop(struct seq_file *f, void *v)
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{
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/* Nothing to do */
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}
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static const struct seq_operations property_op = {
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.start = property_start,
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.next = property_next,
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.stop = property_stop,
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.show = property_show
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};
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static int property_open(struct inode *inode, struct file *file)
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{
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struct op_inode_info *oi = OP_I(inode);
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int ret;
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BUG_ON(oi->type != op_inode_prop);
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ret = seq_open(file, &property_op);
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if (!ret) {
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struct seq_file *m = file->private_data;
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m->private = oi->u.prop;
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}
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return ret;
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}
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static const struct file_operations openpromfs_prop_ops = {
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.open = property_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = seq_release,
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};
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static int openpromfs_readdir(struct file *, void *, filldir_t);
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static const struct file_operations openprom_operations = {
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.read = generic_read_dir,
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.readdir = openpromfs_readdir,
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.llseek = generic_file_llseek,
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};
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static struct dentry *openpromfs_lookup(struct inode *, struct dentry *, struct nameidata *);
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static const struct inode_operations openprom_inode_operations = {
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.lookup = openpromfs_lookup,
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};
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static struct dentry *openpromfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
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{
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struct op_inode_info *ent_oi, *oi = OP_I(dir);
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struct device_node *dp, *child;
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struct property *prop;
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enum op_inode_type ent_type;
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union op_inode_data ent_data;
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const char *name;
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struct inode *inode;
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unsigned int ino;
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int len;
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BUG_ON(oi->type != op_inode_node);
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dp = oi->u.node;
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name = dentry->d_name.name;
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len = dentry->d_name.len;
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mutex_lock(&op_mutex);
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child = dp->child;
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while (child) {
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int n = strlen(child->path_component_name);
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if (len == n &&
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!strncmp(child->path_component_name, name, len)) {
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ent_type = op_inode_node;
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ent_data.node = child;
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ino = child->unique_id;
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goto found;
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}
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child = child->sibling;
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}
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prop = dp->properties;
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while (prop) {
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int n = strlen(prop->name);
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if (len == n && !strncmp(prop->name, name, len)) {
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ent_type = op_inode_prop;
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ent_data.prop = prop;
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ino = prop->unique_id;
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goto found;
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}
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prop = prop->next;
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}
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mutex_unlock(&op_mutex);
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return ERR_PTR(-ENOENT);
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found:
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inode = openprom_iget(dir->i_sb, ino);
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mutex_unlock(&op_mutex);
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if (IS_ERR(inode))
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return ERR_CAST(inode);
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ent_oi = OP_I(inode);
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ent_oi->type = ent_type;
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ent_oi->u = ent_data;
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switch (ent_type) {
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case op_inode_node:
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inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
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inode->i_op = &openprom_inode_operations;
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inode->i_fop = &openprom_operations;
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inode->i_nlink = 2;
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break;
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case op_inode_prop:
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if (!strcmp(dp->name, "options") && (len == 17) &&
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!strncmp (name, "security-password", 17))
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inode->i_mode = S_IFREG | S_IRUSR | S_IWUSR;
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else
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inode->i_mode = S_IFREG | S_IRUGO;
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inode->i_fop = &openpromfs_prop_ops;
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inode->i_nlink = 1;
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inode->i_size = ent_oi->u.prop->length;
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break;
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}
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d_add(dentry, inode);
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return NULL;
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}
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static int openpromfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
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{
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struct inode *inode = filp->f_path.dentry->d_inode;
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struct op_inode_info *oi = OP_I(inode);
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struct device_node *dp = oi->u.node;
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struct device_node *child;
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struct property *prop;
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unsigned int ino;
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int i;
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mutex_lock(&op_mutex);
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ino = inode->i_ino;
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i = filp->f_pos;
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switch (i) {
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case 0:
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if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
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goto out;
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i++;
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filp->f_pos++;
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/* fall thru */
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case 1:
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if (filldir(dirent, "..", 2, i,
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(dp->parent == NULL ?
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OPENPROM_ROOT_INO :
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dp->parent->unique_id), DT_DIR) < 0)
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goto out;
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i++;
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filp->f_pos++;
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/* fall thru */
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default:
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i -= 2;
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/* First, the children nodes as directories. */
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child = dp->child;
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while (i && child) {
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child = child->sibling;
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i--;
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}
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while (child) {
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if (filldir(dirent,
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child->path_component_name,
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strlen(child->path_component_name),
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filp->f_pos, child->unique_id, DT_DIR) < 0)
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goto out;
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filp->f_pos++;
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child = child->sibling;
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}
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/* Next, the properties as files. */
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prop = dp->properties;
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while (i && prop) {
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prop = prop->next;
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i--;
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}
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while (prop) {
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if (filldir(dirent, prop->name, strlen(prop->name),
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filp->f_pos, prop->unique_id, DT_REG) < 0)
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goto out;
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filp->f_pos++;
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prop = prop->next;
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}
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}
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out:
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mutex_unlock(&op_mutex);
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return 0;
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}
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static struct kmem_cache *op_inode_cachep;
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static struct inode *openprom_alloc_inode(struct super_block *sb)
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{
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struct op_inode_info *oi;
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oi = kmem_cache_alloc(op_inode_cachep, GFP_KERNEL);
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if (!oi)
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return NULL;
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return &oi->vfs_inode;
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}
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static void openprom_i_callback(struct rcu_head *head)
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{
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struct inode *inode = container_of(head, struct inode, i_rcu);
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INIT_LIST_HEAD(&inode->i_dentry);
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kmem_cache_free(op_inode_cachep, OP_I(inode));
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}
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static void openprom_destroy_inode(struct inode *inode)
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{
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call_rcu(&inode->i_rcu, openprom_i_callback);
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}
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static struct inode *openprom_iget(struct super_block *sb, ino_t ino)
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{
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struct inode *inode;
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inode = iget_locked(sb, ino);
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if (!inode)
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return ERR_PTR(-ENOMEM);
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if (inode->i_state & I_NEW) {
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inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
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if (inode->i_ino == OPENPROM_ROOT_INO) {
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inode->i_op = &openprom_inode_operations;
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inode->i_fop = &openprom_operations;
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inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
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}
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unlock_new_inode(inode);
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}
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return inode;
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}
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static int openprom_remount(struct super_block *sb, int *flags, char *data)
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{
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*flags |= MS_NOATIME;
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return 0;
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}
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static const struct super_operations openprom_sops = {
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.alloc_inode = openprom_alloc_inode,
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.destroy_inode = openprom_destroy_inode,
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.statfs = simple_statfs,
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.remount_fs = openprom_remount,
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};
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static int openprom_fill_super(struct super_block *s, void *data, int silent)
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{
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struct inode *root_inode;
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struct op_inode_info *oi;
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int ret;
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s->s_flags |= MS_NOATIME;
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s->s_blocksize = 1024;
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s->s_blocksize_bits = 10;
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s->s_magic = OPENPROM_SUPER_MAGIC;
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s->s_op = &openprom_sops;
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s->s_time_gran = 1;
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root_inode = openprom_iget(s, OPENPROM_ROOT_INO);
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if (IS_ERR(root_inode)) {
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ret = PTR_ERR(root_inode);
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goto out_no_root;
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}
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oi = OP_I(root_inode);
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oi->type = op_inode_node;
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oi->u.node = of_find_node_by_path("/");
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s->s_root = d_alloc_root(root_inode);
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if (!s->s_root)
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goto out_no_root_dentry;
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return 0;
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out_no_root_dentry:
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iput(root_inode);
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ret = -ENOMEM;
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out_no_root:
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printk("openprom_fill_super: get root inode failed\n");
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return ret;
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}
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static struct dentry *openprom_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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return mount_single(fs_type, flags, data, openprom_fill_super);
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}
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static struct file_system_type openprom_fs_type = {
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.owner = THIS_MODULE,
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.name = "openpromfs",
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.mount = openprom_mount,
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.kill_sb = kill_anon_super,
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};
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static void op_inode_init_once(void *data)
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{
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struct op_inode_info *oi = (struct op_inode_info *) data;
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inode_init_once(&oi->vfs_inode);
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}
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static int __init init_openprom_fs(void)
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{
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int err;
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op_inode_cachep = kmem_cache_create("op_inode_cache",
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sizeof(struct op_inode_info),
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0,
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(SLAB_RECLAIM_ACCOUNT |
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SLAB_MEM_SPREAD),
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op_inode_init_once);
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if (!op_inode_cachep)
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return -ENOMEM;
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err = register_filesystem(&openprom_fs_type);
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if (err)
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kmem_cache_destroy(op_inode_cachep);
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return err;
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}
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static void __exit exit_openprom_fs(void)
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{
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unregister_filesystem(&openprom_fs_type);
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kmem_cache_destroy(op_inode_cachep);
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}
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module_init(init_openprom_fs)
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module_exit(exit_openprom_fs)
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MODULE_LICENSE("GPL");
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