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/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
This program can be distributed under the terms of the GNU GPL.
See the file COPYING.
*/
#include "fuse_i.h"
#include <linux/init.h>
#include <linux/module.h>
#define FUSE_CTL_SUPER_MAGIC 0x65735543
/*
* This is non-NULL when the single instance of the control filesystem
* exists. Protected by fuse_mutex
*/
static struct super_block *fuse_control_sb;
static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
{
struct fuse_conn *fc;
mutex_lock(&fuse_mutex);
fc = file->f_path.dentry->d_inode->i_private;
if (fc)
fc = fuse_conn_get(fc);
mutex_unlock(&fuse_mutex);
return fc;
}
static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
if (fc) {
fuse_abort_conn(fc);
fuse_conn_put(fc);
}
return count;
}
static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
char tmp[32];
size_t size;
if (!*ppos) {
long value;
struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
if (!fc)
return 0;
value = atomic_read(&fc->num_waiting);
file->private_data = (void *)value;
fuse_conn_put(fc);
}
size = sprintf(tmp, "%ld\n", (long)file->private_data);
return simple_read_from_buffer(buf, len, ppos, tmp, size);
}
static const struct file_operations fuse_ctl_abort_ops = {
.open = nonseekable_open,
.write = fuse_conn_abort_write,
};
static const struct file_operations fuse_ctl_waiting_ops = {
.open = nonseekable_open,
.read = fuse_conn_waiting_read,
};
static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
struct fuse_conn *fc,
const char *name,
int mode, int nlink,
const struct inode_operations *iop,
const struct file_operations *fop)
{
struct dentry *dentry;
struct inode *inode;
BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
dentry = d_alloc_name(parent, name);
if (!dentry)
return NULL;
fc->ctl_dentry[fc->ctl_ndents++] = dentry;
inode = new_inode(fuse_control_sb);
if (!inode)
return NULL;
inode->i_mode = mode;
inode->i_uid = fc->user_id;
inode->i_gid = fc->group_id;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
/* setting ->i_op to NULL is not allowed */
if (iop)
inode->i_op = iop;
inode->i_fop = fop;
inode->i_nlink = nlink;
inode->i_private = fc;
d_add(dentry, inode);
return dentry;
}
/*
* Add a connection to the control filesystem (if it exists). Caller
* must hold fuse_mutex
*/
int fuse_ctl_add_conn(struct fuse_conn *fc)
{
struct dentry *parent;
char name[32];
if (!fuse_control_sb)
return 0;
parent = fuse_control_sb->s_root;
inc_nlink(parent->d_inode);
sprintf(name, "%u", fc->dev);
parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
&simple_dir_inode_operations,
&simple_dir_operations);
if (!parent)
goto err;
if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
NULL, &fuse_ctl_waiting_ops) ||
!fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
NULL, &fuse_ctl_abort_ops))
goto err;
return 0;
err:
fuse_ctl_remove_conn(fc);
return -ENOMEM;
}
/*
* Remove a connection from the control filesystem (if it exists).
* Caller must hold fuse_mutex
*/
void fuse_ctl_remove_conn(struct fuse_conn *fc)
{
int i;
if (!fuse_control_sb)
return;
for (i = fc->ctl_ndents - 1; i >= 0; i--) {
struct dentry *dentry = fc->ctl_dentry[i];
dentry->d_inode->i_private = NULL;
d_drop(dentry);
dput(dentry);
}
fuse_control_sb->s_root->d_inode->i_nlink--;
}
static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
{
struct tree_descr empty_descr = {""};
struct fuse_conn *fc;
int err;
err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
if (err)
return err;
mutex_lock(&fuse_mutex);
BUG_ON(fuse_control_sb);
fuse_control_sb = sb;
list_for_each_entry(fc, &fuse_conn_list, entry) {
err = fuse_ctl_add_conn(fc);
if (err) {
fuse_control_sb = NULL;
mutex_unlock(&fuse_mutex);
return err;
}
}
mutex_unlock(&fuse_mutex);
return 0;
}
static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags,
const char *dev_name, void *raw_data,
struct vfsmount *mnt)
{
return get_sb_single(fs_type, flags, raw_data,
fuse_ctl_fill_super, mnt);
}
static void fuse_ctl_kill_sb(struct super_block *sb)
{
struct fuse_conn *fc;
mutex_lock(&fuse_mutex);
fuse_control_sb = NULL;
list_for_each_entry(fc, &fuse_conn_list, entry)
fc->ctl_ndents = 0;
mutex_unlock(&fuse_mutex);
kill_litter_super(sb);
}
static struct file_system_type fuse_ctl_fs_type = {
.owner = THIS_MODULE,
.name = "fusectl",
.get_sb = fuse_ctl_get_sb,
.kill_sb = fuse_ctl_kill_sb,
};
int __init fuse_ctl_init(void)
{
return register_filesystem(&fuse_ctl_fs_type);
}
void fuse_ctl_cleanup(void)
{
unregister_filesystem(&fuse_ctl_fs_type);
}
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