2 FUSE: Filesystem in Userspace
3 Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
5 This program can be distributed under the terms of the GNU GPL.
11 #include <linux/init.h>
12 #include <linux/module.h>
14 #define FUSE_CTL_SUPER_MAGIC 0x65735543
17 * This is non-NULL when the single instance of the control filesystem
18 * exists. Protected by fuse_mutex
20 static struct super_block *fuse_control_sb;
22 static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
25 mutex_lock(&fuse_mutex);
26 fc = file->f_path.dentry->d_inode->i_private;
28 fc = fuse_conn_get(fc);
29 mutex_unlock(&fuse_mutex);
33 static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
34 size_t count, loff_t *ppos)
36 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
44 static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
45 size_t len, loff_t *ppos)
52 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
56 value = atomic_read(&fc->num_waiting);
57 file->private_data = (void *)value;
60 size = sprintf(tmp, "%ld\n", (long)file->private_data);
61 return simple_read_from_buffer(buf, len, ppos, tmp, size);
64 static ssize_t fuse_conn_limit_read(struct file *file, char __user *buf,
65 size_t len, loff_t *ppos, unsigned val)
68 size_t size = sprintf(tmp, "%u\n", val);
70 return simple_read_from_buffer(buf, len, ppos, tmp, size);
73 static ssize_t fuse_conn_limit_write(struct file *file, const char __user *buf,
74 size_t count, loff_t *ppos, unsigned *val,
75 unsigned global_limit)
79 unsigned limit = (1 << 16) - 1;
82 if (*ppos || count >= sizeof(tmp) - 1)
85 if (copy_from_user(tmp, buf, count))
90 err = strict_strtoul(tmp, 0, &t);
94 if (!capable(CAP_SYS_ADMIN))
95 limit = min(limit, global_limit);
105 static ssize_t fuse_conn_max_background_read(struct file *file,
106 char __user *buf, size_t len,
109 struct fuse_conn *fc;
112 fc = fuse_ctl_file_conn_get(file);
116 val = fc->max_background;
119 return fuse_conn_limit_read(file, buf, len, ppos, val);
122 static ssize_t fuse_conn_max_background_write(struct file *file,
123 const char __user *buf,
124 size_t count, loff_t *ppos)
129 ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
132 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
134 fc->max_background = val;
142 static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
143 char __user *buf, size_t len,
146 struct fuse_conn *fc;
149 fc = fuse_ctl_file_conn_get(file);
153 val = fc->congestion_threshold;
156 return fuse_conn_limit_read(file, buf, len, ppos, val);
159 static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
160 const char __user *buf,
161 size_t count, loff_t *ppos)
166 ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
167 max_user_congthresh);
169 struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
171 fc->congestion_threshold = val;
179 static const struct file_operations fuse_ctl_abort_ops = {
180 .open = nonseekable_open,
181 .write = fuse_conn_abort_write,
185 static const struct file_operations fuse_ctl_waiting_ops = {
186 .open = nonseekable_open,
187 .read = fuse_conn_waiting_read,
191 static const struct file_operations fuse_conn_max_background_ops = {
192 .open = nonseekable_open,
193 .read = fuse_conn_max_background_read,
194 .write = fuse_conn_max_background_write,
198 static const struct file_operations fuse_conn_congestion_threshold_ops = {
199 .open = nonseekable_open,
200 .read = fuse_conn_congestion_threshold_read,
201 .write = fuse_conn_congestion_threshold_write,
205 static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
206 struct fuse_conn *fc,
209 const struct inode_operations *iop,
210 const struct file_operations *fop)
212 struct dentry *dentry;
215 BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
216 dentry = d_alloc_name(parent, name);
220 fc->ctl_dentry[fc->ctl_ndents++] = dentry;
221 inode = new_inode(fuse_control_sb);
225 inode->i_ino = get_next_ino();
226 inode->i_mode = mode;
227 inode->i_uid = fc->user_id;
228 inode->i_gid = fc->group_id;
229 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
230 /* setting ->i_op to NULL is not allowed */
234 set_nlink(inode, nlink);
235 inode->i_private = fc;
236 d_add(dentry, inode);
241 * Add a connection to the control filesystem (if it exists). Caller
242 * must hold fuse_mutex
244 int fuse_ctl_add_conn(struct fuse_conn *fc)
246 struct dentry *parent;
249 if (!fuse_control_sb)
252 parent = fuse_control_sb->s_root;
253 inc_nlink(parent->d_inode);
254 sprintf(name, "%u", fc->dev);
255 parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
256 &simple_dir_inode_operations,
257 &simple_dir_operations);
261 if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
262 NULL, &fuse_ctl_waiting_ops) ||
263 !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
264 NULL, &fuse_ctl_abort_ops) ||
265 !fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
266 1, NULL, &fuse_conn_max_background_ops) ||
267 !fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
268 S_IFREG | 0600, 1, NULL,
269 &fuse_conn_congestion_threshold_ops))
275 fuse_ctl_remove_conn(fc);
280 * Remove a connection from the control filesystem (if it exists).
281 * Caller must hold fuse_mutex
283 void fuse_ctl_remove_conn(struct fuse_conn *fc)
287 if (!fuse_control_sb)
290 for (i = fc->ctl_ndents - 1; i >= 0; i--) {
291 struct dentry *dentry = fc->ctl_dentry[i];
292 dentry->d_inode->i_private = NULL;
296 drop_nlink(fuse_control_sb->s_root->d_inode);
299 static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
301 struct tree_descr empty_descr = {""};
302 struct fuse_conn *fc;
305 err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
309 mutex_lock(&fuse_mutex);
310 BUG_ON(fuse_control_sb);
311 fuse_control_sb = sb;
312 list_for_each_entry(fc, &fuse_conn_list, entry) {
313 err = fuse_ctl_add_conn(fc);
315 fuse_control_sb = NULL;
316 mutex_unlock(&fuse_mutex);
320 mutex_unlock(&fuse_mutex);
325 static struct dentry *fuse_ctl_mount(struct file_system_type *fs_type,
326 int flags, const char *dev_name, void *raw_data)
328 return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
331 static void fuse_ctl_kill_sb(struct super_block *sb)
333 struct fuse_conn *fc;
335 mutex_lock(&fuse_mutex);
336 fuse_control_sb = NULL;
337 list_for_each_entry(fc, &fuse_conn_list, entry)
339 mutex_unlock(&fuse_mutex);
341 kill_litter_super(sb);
344 static struct file_system_type fuse_ctl_fs_type = {
345 .owner = THIS_MODULE,
347 .mount = fuse_ctl_mount,
348 .kill_sb = fuse_ctl_kill_sb,
351 int __init fuse_ctl_init(void)
353 return register_filesystem(&fuse_ctl_fs_type);
356 void fuse_ctl_cleanup(void)
358 unregister_filesystem(&fuse_ctl_fs_type);