1 /* 2 FUSE: Filesystem in Userspace 3 Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu> 4 5 This program can be distributed under the terms of the GNU GPL. 6 See the file COPYING. 7 */ 8 9 #include "fuse_i.h" 10 11 #include <linux/init.h> 12 #include <linux/module.h> 13 14 #define FUSE_CTL_SUPER_MAGIC 0x65735543 15 16 /* 17 * This is non-NULL when the single instance of the control filesystem 18 * exists. Protected by fuse_mutex 19 */ 20 static struct super_block *fuse_control_sb; 21 22 static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file) 23 { 24 struct fuse_conn *fc; 25 mutex_lock(&fuse_mutex); 26 fc = file->f_path.dentry->d_inode->i_private; 27 if (fc) 28 fc = fuse_conn_get(fc); 29 mutex_unlock(&fuse_mutex); 30 return fc; 31 } 32 33 static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf, 34 size_t count, loff_t *ppos) 35 { 36 struct fuse_conn *fc = fuse_ctl_file_conn_get(file); 37 if (fc) { 38 fuse_abort_conn(fc); 39 fuse_conn_put(fc); 40 } 41 return count; 42 } 43 44 static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf, 45 size_t len, loff_t *ppos) 46 { 47 char tmp[32]; 48 size_t size; 49 50 if (!*ppos) { 51 long value; 52 struct fuse_conn *fc = fuse_ctl_file_conn_get(file); 53 if (!fc) 54 return 0; 55 56 value = atomic_read(&fc->num_waiting); 57 file->private_data = (void *)value; 58 fuse_conn_put(fc); 59 } 60 size = sprintf(tmp, "%ld\n", (long)file->private_data); 61 return simple_read_from_buffer(buf, len, ppos, tmp, size); 62 } 63 64 static ssize_t fuse_conn_limit_read(struct file *file, char __user *buf, 65 size_t len, loff_t *ppos, unsigned val) 66 { 67 char tmp[32]; 68 size_t size = sprintf(tmp, "%u\n", val); 69 70 return simple_read_from_buffer(buf, len, ppos, tmp, size); 71 } 72 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) 76 { 77 unsigned long t; 78 char tmp[32]; 79 unsigned limit = (1 << 16) - 1; 80 int err; 81 82 if (*ppos || count >= sizeof(tmp) - 1) 83 return -EINVAL; 84 85 if (copy_from_user(tmp, buf, count)) 86 return -EINVAL; 87 88 tmp[count] = '\0'; 89 90 err = strict_strtoul(tmp, 0, &t); 91 if (err) 92 return err; 93 94 if (!capable(CAP_SYS_ADMIN)) 95 limit = min(limit, global_limit); 96 97 if (t > limit) 98 return -EINVAL; 99 100 *val = t; 101 102 return count; 103 } 104 105 static ssize_t fuse_conn_max_background_read(struct file *file, 106 char __user *buf, size_t len, 107 loff_t *ppos) 108 { 109 struct fuse_conn *fc; 110 unsigned val; 111 112 fc = fuse_ctl_file_conn_get(file); 113 if (!fc) 114 return 0; 115 116 val = fc->max_background; 117 fuse_conn_put(fc); 118 119 return fuse_conn_limit_read(file, buf, len, ppos, val); 120 } 121 122 static ssize_t fuse_conn_max_background_write(struct file *file, 123 const char __user *buf, 124 size_t count, loff_t *ppos) 125 { 126 unsigned val; 127 ssize_t ret; 128 129 ret = fuse_conn_limit_write(file, buf, count, ppos, &val, 130 max_user_bgreq); 131 if (ret > 0) { 132 struct fuse_conn *fc = fuse_ctl_file_conn_get(file); 133 if (fc) { 134 fc->max_background = val; 135 fuse_conn_put(fc); 136 } 137 } 138 139 return ret; 140 } 141 142 static ssize_t fuse_conn_congestion_threshold_read(struct file *file, 143 char __user *buf, size_t len, 144 loff_t *ppos) 145 { 146 struct fuse_conn *fc; 147 unsigned val; 148 149 fc = fuse_ctl_file_conn_get(file); 150 if (!fc) 151 return 0; 152 153 val = fc->congestion_threshold; 154 fuse_conn_put(fc); 155 156 return fuse_conn_limit_read(file, buf, len, ppos, val); 157 } 158 159 static ssize_t fuse_conn_congestion_threshold_write(struct file *file, 160 const char __user *buf, 161 size_t count, loff_t *ppos) 162 { 163 unsigned val; 164 ssize_t ret; 165 166 ret = fuse_conn_limit_write(file, buf, count, ppos, &val, 167 max_user_congthresh); 168 if (ret > 0) { 169 struct fuse_conn *fc = fuse_ctl_file_conn_get(file); 170 if (fc) { 171 fc->congestion_threshold = val; 172 fuse_conn_put(fc); 173 } 174 } 175 176 return ret; 177 } 178 179 static const struct file_operations fuse_ctl_abort_ops = { 180 .open = nonseekable_open, 181 .write = fuse_conn_abort_write, 182 .llseek = no_llseek, 183 }; 184 185 static const struct file_operations fuse_ctl_waiting_ops = { 186 .open = nonseekable_open, 187 .read = fuse_conn_waiting_read, 188 .llseek = no_llseek, 189 }; 190 191 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, 195 .llseek = no_llseek, 196 }; 197 198 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, 202 .llseek = no_llseek, 203 }; 204 205 static struct dentry *fuse_ctl_add_dentry(struct dentry *parent, 206 struct fuse_conn *fc, 207 const char *name, 208 int mode, int nlink, 209 const struct inode_operations *iop, 210 const struct file_operations *fop) 211 { 212 struct dentry *dentry; 213 struct inode *inode; 214 215 BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES); 216 dentry = d_alloc_name(parent, name); 217 if (!dentry) 218 return NULL; 219 220 fc->ctl_dentry[fc->ctl_ndents++] = dentry; 221 inode = new_inode(fuse_control_sb); 222 if (!inode) 223 return NULL; 224 225 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 */ 231 if (iop) 232 inode->i_op = iop; 233 inode->i_fop = fop; 234 set_nlink(inode, nlink); 235 inode->i_private = fc; 236 d_add(dentry, inode); 237 return dentry; 238 } 239 240 /* 241 * Add a connection to the control filesystem (if it exists). Caller 242 * must hold fuse_mutex 243 */ 244 int fuse_ctl_add_conn(struct fuse_conn *fc) 245 { 246 struct dentry *parent; 247 char name[32]; 248 249 if (!fuse_control_sb) 250 return 0; 251 252 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); 258 if (!parent) 259 goto err; 260 261 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)) 270 goto err; 271 272 return 0; 273 274 err: 275 fuse_ctl_remove_conn(fc); 276 return -ENOMEM; 277 } 278 279 /* 280 * Remove a connection from the control filesystem (if it exists). 281 * Caller must hold fuse_mutex 282 */ 283 void fuse_ctl_remove_conn(struct fuse_conn *fc) 284 { 285 int i; 286 287 if (!fuse_control_sb) 288 return; 289 290 for (i = fc->ctl_ndents - 1; i >= 0; i--) { 291 struct dentry *dentry = fc->ctl_dentry[i]; 292 dentry->d_inode->i_private = NULL; 293 d_drop(dentry); 294 dput(dentry); 295 } 296 drop_nlink(fuse_control_sb->s_root->d_inode); 297 } 298 299 static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent) 300 { 301 struct tree_descr empty_descr = {""}; 302 struct fuse_conn *fc; 303 int err; 304 305 err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr); 306 if (err) 307 return err; 308 309 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); 314 if (err) { 315 fuse_control_sb = NULL; 316 mutex_unlock(&fuse_mutex); 317 return err; 318 } 319 } 320 mutex_unlock(&fuse_mutex); 321 322 return 0; 323 } 324 325 static struct dentry *fuse_ctl_mount(struct file_system_type *fs_type, 326 int flags, const char *dev_name, void *raw_data) 327 { 328 return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super); 329 } 330 331 static void fuse_ctl_kill_sb(struct super_block *sb) 332 { 333 struct fuse_conn *fc; 334 335 mutex_lock(&fuse_mutex); 336 fuse_control_sb = NULL; 337 list_for_each_entry(fc, &fuse_conn_list, entry) 338 fc->ctl_ndents = 0; 339 mutex_unlock(&fuse_mutex); 340 341 kill_litter_super(sb); 342 } 343 344 static struct file_system_type fuse_ctl_fs_type = { 345 .owner = THIS_MODULE, 346 .name = "fusectl", 347 .mount = fuse_ctl_mount, 348 .kill_sb = fuse_ctl_kill_sb, 349 }; 350 351 int __init fuse_ctl_init(void) 352 { 353 return register_filesystem(&fuse_ctl_fs_type); 354 } 355 356 void fuse_ctl_cleanup(void) 357 { 358 unregister_filesystem(&fuse_ctl_fs_type); 359 } 360