Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/fs/locks.c |
| 3 | * |
| 4 | * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls. |
| 5 | * Doug Evans (dje@spiff.uucp), August 07, 1992 |
| 6 | * |
| 7 | * Deadlock detection added. |
| 8 | * FIXME: one thing isn't handled yet: |
| 9 | * - mandatory locks (requires lots of changes elsewhere) |
| 10 | * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994. |
| 11 | * |
| 12 | * Miscellaneous edits, and a total rewrite of posix_lock_file() code. |
| 13 | * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994 |
| 14 | * |
| 15 | * Converted file_lock_table to a linked list from an array, which eliminates |
| 16 | * the limits on how many active file locks are open. |
| 17 | * Chad Page (pageone@netcom.com), November 27, 1994 |
| 18 | * |
| 19 | * Removed dependency on file descriptors. dup()'ed file descriptors now |
| 20 | * get the same locks as the original file descriptors, and a close() on |
| 21 | * any file descriptor removes ALL the locks on the file for the current |
| 22 | * process. Since locks still depend on the process id, locks are inherited |
| 23 | * after an exec() but not after a fork(). This agrees with POSIX, and both |
| 24 | * BSD and SVR4 practice. |
| 25 | * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995 |
| 26 | * |
| 27 | * Scrapped free list which is redundant now that we allocate locks |
| 28 | * dynamically with kmalloc()/kfree(). |
| 29 | * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995 |
| 30 | * |
| 31 | * Implemented two lock personalities - FL_FLOCK and FL_POSIX. |
| 32 | * |
| 33 | * FL_POSIX locks are created with calls to fcntl() and lockf() through the |
| 34 | * fcntl() system call. They have the semantics described above. |
| 35 | * |
| 36 | * FL_FLOCK locks are created with calls to flock(), through the flock() |
| 37 | * system call, which is new. Old C libraries implement flock() via fcntl() |
| 38 | * and will continue to use the old, broken implementation. |
| 39 | * |
| 40 | * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated |
| 41 | * with a file pointer (filp). As a result they can be shared by a parent |
| 42 | * process and its children after a fork(). They are removed when the last |
| 43 | * file descriptor referring to the file pointer is closed (unless explicitly |
| 44 | * unlocked). |
| 45 | * |
| 46 | * FL_FLOCK locks never deadlock, an existing lock is always removed before |
| 47 | * upgrading from shared to exclusive (or vice versa). When this happens |
| 48 | * any processes blocked by the current lock are woken up and allowed to |
| 49 | * run before the new lock is applied. |
| 50 | * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995 |
| 51 | * |
| 52 | * Removed some race conditions in flock_lock_file(), marked other possible |
| 53 | * races. Just grep for FIXME to see them. |
| 54 | * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996. |
| 55 | * |
| 56 | * Addressed Dmitry's concerns. Deadlock checking no longer recursive. |
| 57 | * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep |
| 58 | * once we've checked for blocking and deadlocking. |
| 59 | * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996. |
| 60 | * |
| 61 | * Initial implementation of mandatory locks. SunOS turned out to be |
| 62 | * a rotten model, so I implemented the "obvious" semantics. |
| 63 | * See 'Documentation/mandatory.txt' for details. |
| 64 | * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996. |
| 65 | * |
| 66 | * Don't allow mandatory locks on mmap()'ed files. Added simple functions to |
| 67 | * check if a file has mandatory locks, used by mmap(), open() and creat() to |
| 68 | * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference |
| 69 | * Manual, Section 2. |
| 70 | * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996. |
| 71 | * |
| 72 | * Tidied up block list handling. Added '/proc/locks' interface. |
| 73 | * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996. |
| 74 | * |
| 75 | * Fixed deadlock condition for pathological code that mixes calls to |
| 76 | * flock() and fcntl(). |
| 77 | * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996. |
| 78 | * |
| 79 | * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use |
| 80 | * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to |
| 81 | * guarantee sensible behaviour in the case where file system modules might |
| 82 | * be compiled with different options than the kernel itself. |
| 83 | * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. |
| 84 | * |
| 85 | * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel |
| 86 | * (Thomas.Meckel@mni.fh-giessen.de) for spotting this. |
| 87 | * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. |
| 88 | * |
| 89 | * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK |
| 90 | * locks. Changed process synchronisation to avoid dereferencing locks that |
| 91 | * have already been freed. |
| 92 | * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996. |
| 93 | * |
| 94 | * Made the block list a circular list to minimise searching in the list. |
| 95 | * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996. |
| 96 | * |
| 97 | * Made mandatory locking a mount option. Default is not to allow mandatory |
| 98 | * locking. |
| 99 | * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996. |
| 100 | * |
| 101 | * Some adaptations for NFS support. |
| 102 | * Olaf Kirch (okir@monad.swb.de), Dec 1996, |
| 103 | * |
| 104 | * Fixed /proc/locks interface so that we can't overrun the buffer we are handed. |
| 105 | * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997. |
| 106 | * |
| 107 | * Use slab allocator instead of kmalloc/kfree. |
| 108 | * Use generic list implementation from <linux/list.h>. |
| 109 | * Sped up posix_locks_deadlock by only considering blocked locks. |
| 110 | * Matthew Wilcox <willy@debian.org>, March, 2000. |
| 111 | * |
| 112 | * Leases and LOCK_MAND |
| 113 | * Matthew Wilcox <willy@debian.org>, June, 2000. |
| 114 | * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000. |
| 115 | */ |
| 116 | |
| 117 | #include <linux/capability.h> |
| 118 | #include <linux/file.h> |
| 119 | #include <linux/fs.h> |
| 120 | #include <linux/init.h> |
| 121 | #include <linux/module.h> |
| 122 | #include <linux/security.h> |
| 123 | #include <linux/slab.h> |
| 124 | #include <linux/smp_lock.h> |
| 125 | #include <linux/syscalls.h> |
| 126 | #include <linux/time.h> |
Dipankar Sarma | 4fb3a53 | 2005-09-16 19:28:13 -0700 | [diff] [blame] | 127 | #include <linux/rcupdate.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 128 | |
| 129 | #include <asm/semaphore.h> |
| 130 | #include <asm/uaccess.h> |
| 131 | |
| 132 | #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX) |
| 133 | #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK) |
| 134 | #define IS_LEASE(fl) (fl->fl_flags & FL_LEASE) |
| 135 | |
| 136 | int leases_enable = 1; |
| 137 | int lease_break_time = 45; |
| 138 | |
| 139 | #define for_each_lock(inode, lockp) \ |
| 140 | for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next) |
| 141 | |
| 142 | LIST_HEAD(file_lock_list); |
| 143 | |
| 144 | EXPORT_SYMBOL(file_lock_list); |
| 145 | |
| 146 | static LIST_HEAD(blocked_list); |
| 147 | |
| 148 | static kmem_cache_t *filelock_cache; |
| 149 | |
| 150 | /* Allocate an empty lock structure. */ |
| 151 | static struct file_lock *locks_alloc_lock(void) |
| 152 | { |
| 153 | return kmem_cache_alloc(filelock_cache, SLAB_KERNEL); |
| 154 | } |
| 155 | |
| 156 | /* Free a lock which is not in use. */ |
| 157 | static inline void locks_free_lock(struct file_lock *fl) |
| 158 | { |
| 159 | if (fl == NULL) { |
| 160 | BUG(); |
| 161 | return; |
| 162 | } |
| 163 | if (waitqueue_active(&fl->fl_wait)) |
| 164 | panic("Attempting to free lock with active wait queue"); |
| 165 | |
| 166 | if (!list_empty(&fl->fl_block)) |
| 167 | panic("Attempting to free lock with active block list"); |
| 168 | |
| 169 | if (!list_empty(&fl->fl_link)) |
| 170 | panic("Attempting to free lock on active lock list"); |
| 171 | |
| 172 | if (fl->fl_ops) { |
| 173 | if (fl->fl_ops->fl_release_private) |
| 174 | fl->fl_ops->fl_release_private(fl); |
| 175 | fl->fl_ops = NULL; |
| 176 | } |
| 177 | |
| 178 | if (fl->fl_lmops) { |
| 179 | if (fl->fl_lmops->fl_release_private) |
| 180 | fl->fl_lmops->fl_release_private(fl); |
| 181 | fl->fl_lmops = NULL; |
| 182 | } |
| 183 | |
| 184 | kmem_cache_free(filelock_cache, fl); |
| 185 | } |
| 186 | |
| 187 | void locks_init_lock(struct file_lock *fl) |
| 188 | { |
| 189 | INIT_LIST_HEAD(&fl->fl_link); |
| 190 | INIT_LIST_HEAD(&fl->fl_block); |
| 191 | init_waitqueue_head(&fl->fl_wait); |
| 192 | fl->fl_next = NULL; |
| 193 | fl->fl_fasync = NULL; |
| 194 | fl->fl_owner = NULL; |
| 195 | fl->fl_pid = 0; |
| 196 | fl->fl_file = NULL; |
| 197 | fl->fl_flags = 0; |
| 198 | fl->fl_type = 0; |
| 199 | fl->fl_start = fl->fl_end = 0; |
| 200 | fl->fl_ops = NULL; |
| 201 | fl->fl_lmops = NULL; |
| 202 | } |
| 203 | |
| 204 | EXPORT_SYMBOL(locks_init_lock); |
| 205 | |
| 206 | /* |
| 207 | * Initialises the fields of the file lock which are invariant for |
| 208 | * free file_locks. |
| 209 | */ |
| 210 | static void init_once(void *foo, kmem_cache_t *cache, unsigned long flags) |
| 211 | { |
| 212 | struct file_lock *lock = (struct file_lock *) foo; |
| 213 | |
| 214 | if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) != |
| 215 | SLAB_CTOR_CONSTRUCTOR) |
| 216 | return; |
| 217 | |
| 218 | locks_init_lock(lock); |
| 219 | } |
| 220 | |
| 221 | /* |
| 222 | * Initialize a new lock from an existing file_lock structure. |
| 223 | */ |
| 224 | void locks_copy_lock(struct file_lock *new, struct file_lock *fl) |
| 225 | { |
| 226 | new->fl_owner = fl->fl_owner; |
| 227 | new->fl_pid = fl->fl_pid; |
| 228 | new->fl_file = fl->fl_file; |
| 229 | new->fl_flags = fl->fl_flags; |
| 230 | new->fl_type = fl->fl_type; |
| 231 | new->fl_start = fl->fl_start; |
| 232 | new->fl_end = fl->fl_end; |
| 233 | new->fl_ops = fl->fl_ops; |
| 234 | new->fl_lmops = fl->fl_lmops; |
| 235 | if (fl->fl_ops && fl->fl_ops->fl_copy_lock) |
| 236 | fl->fl_ops->fl_copy_lock(new, fl); |
| 237 | if (fl->fl_lmops && fl->fl_lmops->fl_copy_lock) |
| 238 | fl->fl_lmops->fl_copy_lock(new, fl); |
| 239 | } |
| 240 | |
| 241 | EXPORT_SYMBOL(locks_copy_lock); |
| 242 | |
| 243 | static inline int flock_translate_cmd(int cmd) { |
| 244 | if (cmd & LOCK_MAND) |
| 245 | return cmd & (LOCK_MAND | LOCK_RW); |
| 246 | switch (cmd) { |
| 247 | case LOCK_SH: |
| 248 | return F_RDLCK; |
| 249 | case LOCK_EX: |
| 250 | return F_WRLCK; |
| 251 | case LOCK_UN: |
| 252 | return F_UNLCK; |
| 253 | } |
| 254 | return -EINVAL; |
| 255 | } |
| 256 | |
| 257 | /* Fill in a file_lock structure with an appropriate FLOCK lock. */ |
| 258 | static int flock_make_lock(struct file *filp, struct file_lock **lock, |
| 259 | unsigned int cmd) |
| 260 | { |
| 261 | struct file_lock *fl; |
| 262 | int type = flock_translate_cmd(cmd); |
| 263 | if (type < 0) |
| 264 | return type; |
| 265 | |
| 266 | fl = locks_alloc_lock(); |
| 267 | if (fl == NULL) |
| 268 | return -ENOMEM; |
| 269 | |
| 270 | fl->fl_file = filp; |
| 271 | fl->fl_pid = current->tgid; |
| 272 | fl->fl_flags = FL_FLOCK; |
| 273 | fl->fl_type = type; |
| 274 | fl->fl_end = OFFSET_MAX; |
| 275 | |
| 276 | *lock = fl; |
| 277 | return 0; |
| 278 | } |
| 279 | |
| 280 | static int assign_type(struct file_lock *fl, int type) |
| 281 | { |
| 282 | switch (type) { |
| 283 | case F_RDLCK: |
| 284 | case F_WRLCK: |
| 285 | case F_UNLCK: |
| 286 | fl->fl_type = type; |
| 287 | break; |
| 288 | default: |
| 289 | return -EINVAL; |
| 290 | } |
| 291 | return 0; |
| 292 | } |
| 293 | |
| 294 | /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX |
| 295 | * style lock. |
| 296 | */ |
| 297 | static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, |
| 298 | struct flock *l) |
| 299 | { |
| 300 | off_t start, end; |
| 301 | |
| 302 | switch (l->l_whence) { |
| 303 | case 0: /*SEEK_SET*/ |
| 304 | start = 0; |
| 305 | break; |
| 306 | case 1: /*SEEK_CUR*/ |
| 307 | start = filp->f_pos; |
| 308 | break; |
| 309 | case 2: /*SEEK_END*/ |
| 310 | start = i_size_read(filp->f_dentry->d_inode); |
| 311 | break; |
| 312 | default: |
| 313 | return -EINVAL; |
| 314 | } |
| 315 | |
| 316 | /* POSIX-1996 leaves the case l->l_len < 0 undefined; |
| 317 | POSIX-2001 defines it. */ |
| 318 | start += l->l_start; |
| 319 | end = start + l->l_len - 1; |
| 320 | if (l->l_len < 0) { |
| 321 | end = start - 1; |
| 322 | start += l->l_len; |
| 323 | } |
| 324 | |
| 325 | if (start < 0) |
| 326 | return -EINVAL; |
| 327 | if (l->l_len > 0 && end < 0) |
| 328 | return -EOVERFLOW; |
| 329 | |
| 330 | fl->fl_start = start; /* we record the absolute position */ |
| 331 | fl->fl_end = end; |
| 332 | if (l->l_len == 0) |
| 333 | fl->fl_end = OFFSET_MAX; |
| 334 | |
| 335 | fl->fl_owner = current->files; |
| 336 | fl->fl_pid = current->tgid; |
| 337 | fl->fl_file = filp; |
| 338 | fl->fl_flags = FL_POSIX; |
| 339 | fl->fl_ops = NULL; |
| 340 | fl->fl_lmops = NULL; |
| 341 | |
| 342 | return assign_type(fl, l->l_type); |
| 343 | } |
| 344 | |
| 345 | #if BITS_PER_LONG == 32 |
| 346 | static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, |
| 347 | struct flock64 *l) |
| 348 | { |
| 349 | loff_t start; |
| 350 | |
| 351 | switch (l->l_whence) { |
| 352 | case 0: /*SEEK_SET*/ |
| 353 | start = 0; |
| 354 | break; |
| 355 | case 1: /*SEEK_CUR*/ |
| 356 | start = filp->f_pos; |
| 357 | break; |
| 358 | case 2: /*SEEK_END*/ |
| 359 | start = i_size_read(filp->f_dentry->d_inode); |
| 360 | break; |
| 361 | default: |
| 362 | return -EINVAL; |
| 363 | } |
| 364 | |
| 365 | if (((start += l->l_start) < 0) || (l->l_len < 0)) |
| 366 | return -EINVAL; |
| 367 | fl->fl_end = start + l->l_len - 1; |
| 368 | if (l->l_len > 0 && fl->fl_end < 0) |
| 369 | return -EOVERFLOW; |
| 370 | fl->fl_start = start; /* we record the absolute position */ |
| 371 | if (l->l_len == 0) |
| 372 | fl->fl_end = OFFSET_MAX; |
| 373 | |
| 374 | fl->fl_owner = current->files; |
| 375 | fl->fl_pid = current->tgid; |
| 376 | fl->fl_file = filp; |
| 377 | fl->fl_flags = FL_POSIX; |
| 378 | fl->fl_ops = NULL; |
| 379 | fl->fl_lmops = NULL; |
| 380 | |
| 381 | switch (l->l_type) { |
| 382 | case F_RDLCK: |
| 383 | case F_WRLCK: |
| 384 | case F_UNLCK: |
| 385 | fl->fl_type = l->l_type; |
| 386 | break; |
| 387 | default: |
| 388 | return -EINVAL; |
| 389 | } |
| 390 | |
| 391 | return (0); |
| 392 | } |
| 393 | #endif |
| 394 | |
| 395 | /* default lease lock manager operations */ |
| 396 | static void lease_break_callback(struct file_lock *fl) |
| 397 | { |
| 398 | kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); |
| 399 | } |
| 400 | |
| 401 | static void lease_release_private_callback(struct file_lock *fl) |
| 402 | { |
| 403 | if (!fl->fl_file) |
| 404 | return; |
| 405 | |
| 406 | f_delown(fl->fl_file); |
| 407 | fl->fl_file->f_owner.signum = 0; |
| 408 | } |
| 409 | |
Adrian Bunk | 75c96f8 | 2005-05-05 16:16:09 -0700 | [diff] [blame] | 410 | static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 411 | { |
| 412 | return fl->fl_file == try->fl_file; |
| 413 | } |
| 414 | |
Adrian Bunk | 75c96f8 | 2005-05-05 16:16:09 -0700 | [diff] [blame] | 415 | static struct lock_manager_operations lease_manager_ops = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 416 | .fl_break = lease_break_callback, |
| 417 | .fl_release_private = lease_release_private_callback, |
| 418 | .fl_mylease = lease_mylease_callback, |
| 419 | .fl_change = lease_modify, |
| 420 | }; |
| 421 | |
| 422 | /* |
| 423 | * Initialize a lease, use the default lock manager operations |
| 424 | */ |
| 425 | static int lease_init(struct file *filp, int type, struct file_lock *fl) |
| 426 | { |
| 427 | fl->fl_owner = current->files; |
| 428 | fl->fl_pid = current->tgid; |
| 429 | |
| 430 | fl->fl_file = filp; |
| 431 | fl->fl_flags = FL_LEASE; |
| 432 | if (assign_type(fl, type) != 0) { |
| 433 | locks_free_lock(fl); |
| 434 | return -EINVAL; |
| 435 | } |
| 436 | fl->fl_start = 0; |
| 437 | fl->fl_end = OFFSET_MAX; |
| 438 | fl->fl_ops = NULL; |
| 439 | fl->fl_lmops = &lease_manager_ops; |
| 440 | return 0; |
| 441 | } |
| 442 | |
| 443 | /* Allocate a file_lock initialised to this type of lease */ |
| 444 | static int lease_alloc(struct file *filp, int type, struct file_lock **flp) |
| 445 | { |
| 446 | struct file_lock *fl = locks_alloc_lock(); |
| 447 | int error; |
| 448 | |
| 449 | if (fl == NULL) |
| 450 | return -ENOMEM; |
| 451 | |
| 452 | error = lease_init(filp, type, fl); |
| 453 | if (error) |
| 454 | return error; |
| 455 | *flp = fl; |
| 456 | return 0; |
| 457 | } |
| 458 | |
| 459 | /* Check if two locks overlap each other. |
| 460 | */ |
| 461 | static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) |
| 462 | { |
| 463 | return ((fl1->fl_end >= fl2->fl_start) && |
| 464 | (fl2->fl_end >= fl1->fl_start)); |
| 465 | } |
| 466 | |
| 467 | /* |
| 468 | * Check whether two locks have the same owner. |
| 469 | */ |
| 470 | static inline int |
| 471 | posix_same_owner(struct file_lock *fl1, struct file_lock *fl2) |
| 472 | { |
| 473 | if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner) |
| 474 | return fl2->fl_lmops == fl1->fl_lmops && |
| 475 | fl1->fl_lmops->fl_compare_owner(fl1, fl2); |
| 476 | return fl1->fl_owner == fl2->fl_owner; |
| 477 | } |
| 478 | |
| 479 | /* Remove waiter from blocker's block list. |
| 480 | * When blocker ends up pointing to itself then the list is empty. |
| 481 | */ |
| 482 | static inline void __locks_delete_block(struct file_lock *waiter) |
| 483 | { |
| 484 | list_del_init(&waiter->fl_block); |
| 485 | list_del_init(&waiter->fl_link); |
| 486 | waiter->fl_next = NULL; |
| 487 | } |
| 488 | |
| 489 | /* |
| 490 | */ |
| 491 | static void locks_delete_block(struct file_lock *waiter) |
| 492 | { |
| 493 | lock_kernel(); |
| 494 | __locks_delete_block(waiter); |
| 495 | unlock_kernel(); |
| 496 | } |
| 497 | |
| 498 | /* Insert waiter into blocker's block list. |
| 499 | * We use a circular list so that processes can be easily woken up in |
| 500 | * the order they blocked. The documentation doesn't require this but |
| 501 | * it seems like the reasonable thing to do. |
| 502 | */ |
| 503 | static void locks_insert_block(struct file_lock *blocker, |
| 504 | struct file_lock *waiter) |
| 505 | { |
| 506 | if (!list_empty(&waiter->fl_block)) { |
| 507 | printk(KERN_ERR "locks_insert_block: removing duplicated lock " |
| 508 | "(pid=%d %Ld-%Ld type=%d)\n", waiter->fl_pid, |
| 509 | waiter->fl_start, waiter->fl_end, waiter->fl_type); |
| 510 | __locks_delete_block(waiter); |
| 511 | } |
| 512 | list_add_tail(&waiter->fl_block, &blocker->fl_block); |
| 513 | waiter->fl_next = blocker; |
| 514 | if (IS_POSIX(blocker)) |
| 515 | list_add(&waiter->fl_link, &blocked_list); |
| 516 | } |
| 517 | |
| 518 | /* Wake up processes blocked waiting for blocker. |
| 519 | * If told to wait then schedule the processes until the block list |
| 520 | * is empty, otherwise empty the block list ourselves. |
| 521 | */ |
| 522 | static void locks_wake_up_blocks(struct file_lock *blocker) |
| 523 | { |
| 524 | while (!list_empty(&blocker->fl_block)) { |
| 525 | struct file_lock *waiter = list_entry(blocker->fl_block.next, |
| 526 | struct file_lock, fl_block); |
| 527 | __locks_delete_block(waiter); |
| 528 | if (waiter->fl_lmops && waiter->fl_lmops->fl_notify) |
| 529 | waiter->fl_lmops->fl_notify(waiter); |
| 530 | else |
| 531 | wake_up(&waiter->fl_wait); |
| 532 | } |
| 533 | } |
| 534 | |
| 535 | /* Insert file lock fl into an inode's lock list at the position indicated |
| 536 | * by pos. At the same time add the lock to the global file lock list. |
| 537 | */ |
| 538 | static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl) |
| 539 | { |
| 540 | list_add(&fl->fl_link, &file_lock_list); |
| 541 | |
| 542 | /* insert into file's list */ |
| 543 | fl->fl_next = *pos; |
| 544 | *pos = fl; |
| 545 | |
| 546 | if (fl->fl_ops && fl->fl_ops->fl_insert) |
| 547 | fl->fl_ops->fl_insert(fl); |
| 548 | } |
| 549 | |
| 550 | /* |
| 551 | * Delete a lock and then free it. |
| 552 | * Wake up processes that are blocked waiting for this lock, |
| 553 | * notify the FS that the lock has been cleared and |
| 554 | * finally free the lock. |
| 555 | */ |
| 556 | static void locks_delete_lock(struct file_lock **thisfl_p) |
| 557 | { |
| 558 | struct file_lock *fl = *thisfl_p; |
| 559 | |
| 560 | *thisfl_p = fl->fl_next; |
| 561 | fl->fl_next = NULL; |
| 562 | list_del_init(&fl->fl_link); |
| 563 | |
| 564 | fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync); |
| 565 | if (fl->fl_fasync != NULL) { |
| 566 | printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); |
| 567 | fl->fl_fasync = NULL; |
| 568 | } |
| 569 | |
| 570 | if (fl->fl_ops && fl->fl_ops->fl_remove) |
| 571 | fl->fl_ops->fl_remove(fl); |
| 572 | |
| 573 | locks_wake_up_blocks(fl); |
| 574 | locks_free_lock(fl); |
| 575 | } |
| 576 | |
| 577 | /* Determine if lock sys_fl blocks lock caller_fl. Common functionality |
| 578 | * checks for shared/exclusive status of overlapping locks. |
| 579 | */ |
| 580 | static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) |
| 581 | { |
| 582 | if (sys_fl->fl_type == F_WRLCK) |
| 583 | return 1; |
| 584 | if (caller_fl->fl_type == F_WRLCK) |
| 585 | return 1; |
| 586 | return 0; |
| 587 | } |
| 588 | |
| 589 | /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific |
| 590 | * checking before calling the locks_conflict(). |
| 591 | */ |
| 592 | static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) |
| 593 | { |
| 594 | /* POSIX locks owned by the same process do not conflict with |
| 595 | * each other. |
| 596 | */ |
| 597 | if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl)) |
| 598 | return (0); |
| 599 | |
| 600 | /* Check whether they overlap */ |
| 601 | if (!locks_overlap(caller_fl, sys_fl)) |
| 602 | return 0; |
| 603 | |
| 604 | return (locks_conflict(caller_fl, sys_fl)); |
| 605 | } |
| 606 | |
| 607 | /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific |
| 608 | * checking before calling the locks_conflict(). |
| 609 | */ |
| 610 | static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) |
| 611 | { |
| 612 | /* FLOCK locks referring to the same filp do not conflict with |
| 613 | * each other. |
| 614 | */ |
| 615 | if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file)) |
| 616 | return (0); |
| 617 | if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) |
| 618 | return 0; |
| 619 | |
| 620 | return (locks_conflict(caller_fl, sys_fl)); |
| 621 | } |
| 622 | |
| 623 | static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout) |
| 624 | { |
| 625 | int result = 0; |
| 626 | DECLARE_WAITQUEUE(wait, current); |
| 627 | |
| 628 | __set_current_state(TASK_INTERRUPTIBLE); |
| 629 | add_wait_queue(fl_wait, &wait); |
| 630 | if (timeout == 0) |
| 631 | schedule(); |
| 632 | else |
| 633 | result = schedule_timeout(timeout); |
| 634 | if (signal_pending(current)) |
| 635 | result = -ERESTARTSYS; |
| 636 | remove_wait_queue(fl_wait, &wait); |
| 637 | __set_current_state(TASK_RUNNING); |
| 638 | return result; |
| 639 | } |
| 640 | |
| 641 | static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time) |
| 642 | { |
| 643 | int result; |
| 644 | locks_insert_block(blocker, waiter); |
| 645 | result = interruptible_sleep_on_locked(&waiter->fl_wait, time); |
| 646 | __locks_delete_block(waiter); |
| 647 | return result; |
| 648 | } |
| 649 | |
| 650 | struct file_lock * |
| 651 | posix_test_lock(struct file *filp, struct file_lock *fl) |
| 652 | { |
| 653 | struct file_lock *cfl; |
| 654 | |
| 655 | lock_kernel(); |
| 656 | for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { |
| 657 | if (!IS_POSIX(cfl)) |
| 658 | continue; |
| 659 | if (posix_locks_conflict(cfl, fl)) |
| 660 | break; |
| 661 | } |
| 662 | unlock_kernel(); |
| 663 | |
| 664 | return (cfl); |
| 665 | } |
| 666 | |
| 667 | EXPORT_SYMBOL(posix_test_lock); |
| 668 | |
| 669 | /* This function tests for deadlock condition before putting a process to |
| 670 | * sleep. The detection scheme is no longer recursive. Recursive was neat, |
| 671 | * but dangerous - we risked stack corruption if the lock data was bad, or |
| 672 | * if the recursion was too deep for any other reason. |
| 673 | * |
| 674 | * We rely on the fact that a task can only be on one lock's wait queue |
| 675 | * at a time. When we find blocked_task on a wait queue we can re-search |
| 676 | * with blocked_task equal to that queue's owner, until either blocked_task |
| 677 | * isn't found, or blocked_task is found on a queue owned by my_task. |
| 678 | * |
| 679 | * Note: the above assumption may not be true when handling lock requests |
| 680 | * from a broken NFS client. But broken NFS clients have a lot more to |
| 681 | * worry about than proper deadlock detection anyway... --okir |
| 682 | */ |
| 683 | int posix_locks_deadlock(struct file_lock *caller_fl, |
| 684 | struct file_lock *block_fl) |
| 685 | { |
| 686 | struct list_head *tmp; |
| 687 | |
| 688 | next_task: |
| 689 | if (posix_same_owner(caller_fl, block_fl)) |
| 690 | return 1; |
| 691 | list_for_each(tmp, &blocked_list) { |
| 692 | struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); |
| 693 | if (posix_same_owner(fl, block_fl)) { |
| 694 | fl = fl->fl_next; |
| 695 | block_fl = fl; |
| 696 | goto next_task; |
| 697 | } |
| 698 | } |
| 699 | return 0; |
| 700 | } |
| 701 | |
| 702 | EXPORT_SYMBOL(posix_locks_deadlock); |
| 703 | |
| 704 | /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks |
| 705 | * at the head of the list, but that's secret knowledge known only to |
| 706 | * flock_lock_file and posix_lock_file. |
| 707 | */ |
| 708 | static int flock_lock_file(struct file *filp, struct file_lock *new_fl) |
| 709 | { |
| 710 | struct file_lock **before; |
| 711 | struct inode * inode = filp->f_dentry->d_inode; |
| 712 | int error = 0; |
| 713 | int found = 0; |
| 714 | |
| 715 | lock_kernel(); |
| 716 | for_each_lock(inode, before) { |
| 717 | struct file_lock *fl = *before; |
| 718 | if (IS_POSIX(fl)) |
| 719 | break; |
| 720 | if (IS_LEASE(fl)) |
| 721 | continue; |
| 722 | if (filp != fl->fl_file) |
| 723 | continue; |
| 724 | if (new_fl->fl_type == fl->fl_type) |
| 725 | goto out; |
| 726 | found = 1; |
| 727 | locks_delete_lock(before); |
| 728 | break; |
| 729 | } |
| 730 | unlock_kernel(); |
| 731 | |
| 732 | if (new_fl->fl_type == F_UNLCK) |
| 733 | return 0; |
| 734 | |
| 735 | /* |
| 736 | * If a higher-priority process was blocked on the old file lock, |
| 737 | * give it the opportunity to lock the file. |
| 738 | */ |
| 739 | if (found) |
| 740 | cond_resched(); |
| 741 | |
| 742 | lock_kernel(); |
| 743 | for_each_lock(inode, before) { |
| 744 | struct file_lock *fl = *before; |
| 745 | if (IS_POSIX(fl)) |
| 746 | break; |
| 747 | if (IS_LEASE(fl)) |
| 748 | continue; |
| 749 | if (!flock_locks_conflict(new_fl, fl)) |
| 750 | continue; |
| 751 | error = -EAGAIN; |
| 752 | if (new_fl->fl_flags & FL_SLEEP) { |
| 753 | locks_insert_block(fl, new_fl); |
| 754 | } |
| 755 | goto out; |
| 756 | } |
| 757 | locks_insert_lock(&inode->i_flock, new_fl); |
| 758 | error = 0; |
| 759 | |
| 760 | out: |
| 761 | unlock_kernel(); |
| 762 | return error; |
| 763 | } |
| 764 | |
| 765 | EXPORT_SYMBOL(posix_lock_file); |
| 766 | |
| 767 | static int __posix_lock_file(struct inode *inode, struct file_lock *request) |
| 768 | { |
| 769 | struct file_lock *fl; |
| 770 | struct file_lock *new_fl, *new_fl2; |
| 771 | struct file_lock *left = NULL; |
| 772 | struct file_lock *right = NULL; |
| 773 | struct file_lock **before; |
| 774 | int error, added = 0; |
| 775 | |
| 776 | /* |
| 777 | * We may need two file_lock structures for this operation, |
| 778 | * so we get them in advance to avoid races. |
| 779 | */ |
| 780 | new_fl = locks_alloc_lock(); |
| 781 | new_fl2 = locks_alloc_lock(); |
| 782 | |
| 783 | lock_kernel(); |
| 784 | if (request->fl_type != F_UNLCK) { |
| 785 | for_each_lock(inode, before) { |
| 786 | struct file_lock *fl = *before; |
| 787 | if (!IS_POSIX(fl)) |
| 788 | continue; |
| 789 | if (!posix_locks_conflict(request, fl)) |
| 790 | continue; |
| 791 | error = -EAGAIN; |
| 792 | if (!(request->fl_flags & FL_SLEEP)) |
| 793 | goto out; |
| 794 | error = -EDEADLK; |
| 795 | if (posix_locks_deadlock(request, fl)) |
| 796 | goto out; |
| 797 | error = -EAGAIN; |
| 798 | locks_insert_block(fl, request); |
| 799 | goto out; |
| 800 | } |
| 801 | } |
| 802 | |
| 803 | /* If we're just looking for a conflict, we're done. */ |
| 804 | error = 0; |
| 805 | if (request->fl_flags & FL_ACCESS) |
| 806 | goto out; |
| 807 | |
| 808 | error = -ENOLCK; /* "no luck" */ |
| 809 | if (!(new_fl && new_fl2)) |
| 810 | goto out; |
| 811 | |
| 812 | /* |
| 813 | * We've allocated the new locks in advance, so there are no |
| 814 | * errors possible (and no blocking operations) from here on. |
| 815 | * |
| 816 | * Find the first old lock with the same owner as the new lock. |
| 817 | */ |
| 818 | |
| 819 | before = &inode->i_flock; |
| 820 | |
| 821 | /* First skip locks owned by other processes. */ |
| 822 | while ((fl = *before) && (!IS_POSIX(fl) || |
| 823 | !posix_same_owner(request, fl))) { |
| 824 | before = &fl->fl_next; |
| 825 | } |
| 826 | |
| 827 | /* Process locks with this owner. */ |
| 828 | while ((fl = *before) && posix_same_owner(request, fl)) { |
| 829 | /* Detect adjacent or overlapping regions (if same lock type) |
| 830 | */ |
| 831 | if (request->fl_type == fl->fl_type) { |
Olaf Kirch | 449231d | 2005-08-25 16:25:35 -0700 | [diff] [blame] | 832 | /* In all comparisons of start vs end, use |
| 833 | * "start - 1" rather than "end + 1". If end |
| 834 | * is OFFSET_MAX, end + 1 will become negative. |
| 835 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 836 | if (fl->fl_end < request->fl_start - 1) |
| 837 | goto next_lock; |
| 838 | /* If the next lock in the list has entirely bigger |
| 839 | * addresses than the new one, insert the lock here. |
| 840 | */ |
Olaf Kirch | 449231d | 2005-08-25 16:25:35 -0700 | [diff] [blame] | 841 | if (fl->fl_start - 1 > request->fl_end) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 842 | break; |
| 843 | |
| 844 | /* If we come here, the new and old lock are of the |
| 845 | * same type and adjacent or overlapping. Make one |
| 846 | * lock yielding from the lower start address of both |
| 847 | * locks to the higher end address. |
| 848 | */ |
| 849 | if (fl->fl_start > request->fl_start) |
| 850 | fl->fl_start = request->fl_start; |
| 851 | else |
| 852 | request->fl_start = fl->fl_start; |
| 853 | if (fl->fl_end < request->fl_end) |
| 854 | fl->fl_end = request->fl_end; |
| 855 | else |
| 856 | request->fl_end = fl->fl_end; |
| 857 | if (added) { |
| 858 | locks_delete_lock(before); |
| 859 | continue; |
| 860 | } |
| 861 | request = fl; |
| 862 | added = 1; |
| 863 | } |
| 864 | else { |
| 865 | /* Processing for different lock types is a bit |
| 866 | * more complex. |
| 867 | */ |
| 868 | if (fl->fl_end < request->fl_start) |
| 869 | goto next_lock; |
| 870 | if (fl->fl_start > request->fl_end) |
| 871 | break; |
| 872 | if (request->fl_type == F_UNLCK) |
| 873 | added = 1; |
| 874 | if (fl->fl_start < request->fl_start) |
| 875 | left = fl; |
| 876 | /* If the next lock in the list has a higher end |
| 877 | * address than the new one, insert the new one here. |
| 878 | */ |
| 879 | if (fl->fl_end > request->fl_end) { |
| 880 | right = fl; |
| 881 | break; |
| 882 | } |
| 883 | if (fl->fl_start >= request->fl_start) { |
| 884 | /* The new lock completely replaces an old |
| 885 | * one (This may happen several times). |
| 886 | */ |
| 887 | if (added) { |
| 888 | locks_delete_lock(before); |
| 889 | continue; |
| 890 | } |
| 891 | /* Replace the old lock with the new one. |
| 892 | * Wake up anybody waiting for the old one, |
| 893 | * as the change in lock type might satisfy |
| 894 | * their needs. |
| 895 | */ |
| 896 | locks_wake_up_blocks(fl); |
| 897 | fl->fl_start = request->fl_start; |
| 898 | fl->fl_end = request->fl_end; |
| 899 | fl->fl_type = request->fl_type; |
| 900 | fl->fl_u = request->fl_u; |
| 901 | request = fl; |
| 902 | added = 1; |
| 903 | } |
| 904 | } |
| 905 | /* Go on to next lock. |
| 906 | */ |
| 907 | next_lock: |
| 908 | before = &fl->fl_next; |
| 909 | } |
| 910 | |
| 911 | error = 0; |
| 912 | if (!added) { |
| 913 | if (request->fl_type == F_UNLCK) |
| 914 | goto out; |
| 915 | locks_copy_lock(new_fl, request); |
| 916 | locks_insert_lock(before, new_fl); |
| 917 | new_fl = NULL; |
| 918 | } |
| 919 | if (right) { |
| 920 | if (left == right) { |
| 921 | /* The new lock breaks the old one in two pieces, |
| 922 | * so we have to use the second new lock. |
| 923 | */ |
| 924 | left = new_fl2; |
| 925 | new_fl2 = NULL; |
| 926 | locks_copy_lock(left, right); |
| 927 | locks_insert_lock(before, left); |
| 928 | } |
| 929 | right->fl_start = request->fl_end + 1; |
| 930 | locks_wake_up_blocks(right); |
| 931 | } |
| 932 | if (left) { |
| 933 | left->fl_end = request->fl_start - 1; |
| 934 | locks_wake_up_blocks(left); |
| 935 | } |
| 936 | out: |
| 937 | unlock_kernel(); |
| 938 | /* |
| 939 | * Free any unused locks. |
| 940 | */ |
| 941 | if (new_fl) |
| 942 | locks_free_lock(new_fl); |
| 943 | if (new_fl2) |
| 944 | locks_free_lock(new_fl2); |
| 945 | return error; |
| 946 | } |
| 947 | |
| 948 | /** |
| 949 | * posix_lock_file - Apply a POSIX-style lock to a file |
| 950 | * @filp: The file to apply the lock to |
| 951 | * @fl: The lock to be applied |
| 952 | * |
| 953 | * Add a POSIX style lock to a file. |
| 954 | * We merge adjacent & overlapping locks whenever possible. |
| 955 | * POSIX locks are sorted by owner task, then by starting address |
| 956 | */ |
| 957 | int posix_lock_file(struct file *filp, struct file_lock *fl) |
| 958 | { |
| 959 | return __posix_lock_file(filp->f_dentry->d_inode, fl); |
| 960 | } |
| 961 | |
| 962 | /** |
| 963 | * posix_lock_file_wait - Apply a POSIX-style lock to a file |
| 964 | * @filp: The file to apply the lock to |
| 965 | * @fl: The lock to be applied |
| 966 | * |
| 967 | * Add a POSIX style lock to a file. |
| 968 | * We merge adjacent & overlapping locks whenever possible. |
| 969 | * POSIX locks are sorted by owner task, then by starting address |
| 970 | */ |
| 971 | int posix_lock_file_wait(struct file *filp, struct file_lock *fl) |
| 972 | { |
| 973 | int error; |
| 974 | might_sleep (); |
| 975 | for (;;) { |
| 976 | error = __posix_lock_file(filp->f_dentry->d_inode, fl); |
| 977 | if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) |
| 978 | break; |
| 979 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); |
| 980 | if (!error) |
| 981 | continue; |
| 982 | |
| 983 | locks_delete_block(fl); |
| 984 | break; |
| 985 | } |
| 986 | return error; |
| 987 | } |
| 988 | EXPORT_SYMBOL(posix_lock_file_wait); |
| 989 | |
| 990 | /** |
| 991 | * locks_mandatory_locked - Check for an active lock |
| 992 | * @inode: the file to check |
| 993 | * |
| 994 | * Searches the inode's list of locks to find any POSIX locks which conflict. |
| 995 | * This function is called from locks_verify_locked() only. |
| 996 | */ |
| 997 | int locks_mandatory_locked(struct inode *inode) |
| 998 | { |
| 999 | fl_owner_t owner = current->files; |
| 1000 | struct file_lock *fl; |
| 1001 | |
| 1002 | /* |
| 1003 | * Search the lock list for this inode for any POSIX locks. |
| 1004 | */ |
| 1005 | lock_kernel(); |
| 1006 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { |
| 1007 | if (!IS_POSIX(fl)) |
| 1008 | continue; |
| 1009 | if (fl->fl_owner != owner) |
| 1010 | break; |
| 1011 | } |
| 1012 | unlock_kernel(); |
| 1013 | return fl ? -EAGAIN : 0; |
| 1014 | } |
| 1015 | |
| 1016 | /** |
| 1017 | * locks_mandatory_area - Check for a conflicting lock |
| 1018 | * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ |
| 1019 | * for shared |
| 1020 | * @inode: the file to check |
| 1021 | * @filp: how the file was opened (if it was) |
| 1022 | * @offset: start of area to check |
| 1023 | * @count: length of area to check |
| 1024 | * |
| 1025 | * Searches the inode's list of locks to find any POSIX locks which conflict. |
| 1026 | * This function is called from rw_verify_area() and |
| 1027 | * locks_verify_truncate(). |
| 1028 | */ |
| 1029 | int locks_mandatory_area(int read_write, struct inode *inode, |
| 1030 | struct file *filp, loff_t offset, |
| 1031 | size_t count) |
| 1032 | { |
| 1033 | struct file_lock fl; |
| 1034 | int error; |
| 1035 | |
| 1036 | locks_init_lock(&fl); |
| 1037 | fl.fl_owner = current->files; |
| 1038 | fl.fl_pid = current->tgid; |
| 1039 | fl.fl_file = filp; |
| 1040 | fl.fl_flags = FL_POSIX | FL_ACCESS; |
| 1041 | if (filp && !(filp->f_flags & O_NONBLOCK)) |
| 1042 | fl.fl_flags |= FL_SLEEP; |
| 1043 | fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK; |
| 1044 | fl.fl_start = offset; |
| 1045 | fl.fl_end = offset + count - 1; |
| 1046 | |
| 1047 | for (;;) { |
| 1048 | error = __posix_lock_file(inode, &fl); |
| 1049 | if (error != -EAGAIN) |
| 1050 | break; |
| 1051 | if (!(fl.fl_flags & FL_SLEEP)) |
| 1052 | break; |
| 1053 | error = wait_event_interruptible(fl.fl_wait, !fl.fl_next); |
| 1054 | if (!error) { |
| 1055 | /* |
| 1056 | * If we've been sleeping someone might have |
| 1057 | * changed the permissions behind our back. |
| 1058 | */ |
| 1059 | if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID) |
| 1060 | continue; |
| 1061 | } |
| 1062 | |
| 1063 | locks_delete_block(&fl); |
| 1064 | break; |
| 1065 | } |
| 1066 | |
| 1067 | return error; |
| 1068 | } |
| 1069 | |
| 1070 | EXPORT_SYMBOL(locks_mandatory_area); |
| 1071 | |
| 1072 | /* We already had a lease on this file; just change its type */ |
| 1073 | int lease_modify(struct file_lock **before, int arg) |
| 1074 | { |
| 1075 | struct file_lock *fl = *before; |
| 1076 | int error = assign_type(fl, arg); |
| 1077 | |
| 1078 | if (error) |
| 1079 | return error; |
| 1080 | locks_wake_up_blocks(fl); |
| 1081 | if (arg == F_UNLCK) |
| 1082 | locks_delete_lock(before); |
| 1083 | return 0; |
| 1084 | } |
| 1085 | |
| 1086 | EXPORT_SYMBOL(lease_modify); |
| 1087 | |
| 1088 | static void time_out_leases(struct inode *inode) |
| 1089 | { |
| 1090 | struct file_lock **before; |
| 1091 | struct file_lock *fl; |
| 1092 | |
| 1093 | before = &inode->i_flock; |
| 1094 | while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) { |
| 1095 | if ((fl->fl_break_time == 0) |
| 1096 | || time_before(jiffies, fl->fl_break_time)) { |
| 1097 | before = &fl->fl_next; |
| 1098 | continue; |
| 1099 | } |
| 1100 | printk(KERN_INFO "lease broken - owner pid = %d\n", fl->fl_pid); |
| 1101 | lease_modify(before, fl->fl_type & ~F_INPROGRESS); |
| 1102 | if (fl == *before) /* lease_modify may have freed fl */ |
| 1103 | before = &fl->fl_next; |
| 1104 | } |
| 1105 | } |
| 1106 | |
| 1107 | /** |
| 1108 | * __break_lease - revoke all outstanding leases on file |
| 1109 | * @inode: the inode of the file to return |
| 1110 | * @mode: the open mode (read or write) |
| 1111 | * |
| 1112 | * break_lease (inlined for speed) has checked there already |
| 1113 | * is a lease on this file. Leases are broken on a call to open() |
| 1114 | * or truncate(). This function can sleep unless you |
| 1115 | * specified %O_NONBLOCK to your open(). |
| 1116 | */ |
| 1117 | int __break_lease(struct inode *inode, unsigned int mode) |
| 1118 | { |
| 1119 | int error = 0, future; |
| 1120 | struct file_lock *new_fl, *flock; |
| 1121 | struct file_lock *fl; |
| 1122 | int alloc_err; |
| 1123 | unsigned long break_time; |
| 1124 | int i_have_this_lease = 0; |
| 1125 | |
| 1126 | alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK, |
| 1127 | &new_fl); |
| 1128 | |
| 1129 | lock_kernel(); |
| 1130 | |
| 1131 | time_out_leases(inode); |
| 1132 | |
| 1133 | flock = inode->i_flock; |
| 1134 | if ((flock == NULL) || !IS_LEASE(flock)) |
| 1135 | goto out; |
| 1136 | |
| 1137 | for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) |
| 1138 | if (fl->fl_owner == current->files) |
| 1139 | i_have_this_lease = 1; |
| 1140 | |
| 1141 | if (mode & FMODE_WRITE) { |
| 1142 | /* If we want write access, we have to revoke any lease. */ |
| 1143 | future = F_UNLCK | F_INPROGRESS; |
| 1144 | } else if (flock->fl_type & F_INPROGRESS) { |
| 1145 | /* If the lease is already being broken, we just leave it */ |
| 1146 | future = flock->fl_type; |
| 1147 | } else if (flock->fl_type & F_WRLCK) { |
| 1148 | /* Downgrade the exclusive lease to a read-only lease. */ |
| 1149 | future = F_RDLCK | F_INPROGRESS; |
| 1150 | } else { |
| 1151 | /* the existing lease was read-only, so we can read too. */ |
| 1152 | goto out; |
| 1153 | } |
| 1154 | |
| 1155 | if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) { |
| 1156 | error = alloc_err; |
| 1157 | goto out; |
| 1158 | } |
| 1159 | |
| 1160 | break_time = 0; |
| 1161 | if (lease_break_time > 0) { |
| 1162 | break_time = jiffies + lease_break_time * HZ; |
| 1163 | if (break_time == 0) |
| 1164 | break_time++; /* so that 0 means no break time */ |
| 1165 | } |
| 1166 | |
| 1167 | for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) { |
| 1168 | if (fl->fl_type != future) { |
| 1169 | fl->fl_type = future; |
| 1170 | fl->fl_break_time = break_time; |
| 1171 | /* lease must have lmops break callback */ |
| 1172 | fl->fl_lmops->fl_break(fl); |
| 1173 | } |
| 1174 | } |
| 1175 | |
| 1176 | if (i_have_this_lease || (mode & O_NONBLOCK)) { |
| 1177 | error = -EWOULDBLOCK; |
| 1178 | goto out; |
| 1179 | } |
| 1180 | |
| 1181 | restart: |
| 1182 | break_time = flock->fl_break_time; |
| 1183 | if (break_time != 0) { |
| 1184 | break_time -= jiffies; |
| 1185 | if (break_time == 0) |
| 1186 | break_time++; |
| 1187 | } |
| 1188 | error = locks_block_on_timeout(flock, new_fl, break_time); |
| 1189 | if (error >= 0) { |
| 1190 | if (error == 0) |
| 1191 | time_out_leases(inode); |
| 1192 | /* Wait for the next lease that has not been broken yet */ |
| 1193 | for (flock = inode->i_flock; flock && IS_LEASE(flock); |
| 1194 | flock = flock->fl_next) { |
| 1195 | if (flock->fl_type & F_INPROGRESS) |
| 1196 | goto restart; |
| 1197 | } |
| 1198 | error = 0; |
| 1199 | } |
| 1200 | |
| 1201 | out: |
| 1202 | unlock_kernel(); |
| 1203 | if (!alloc_err) |
| 1204 | locks_free_lock(new_fl); |
| 1205 | return error; |
| 1206 | } |
| 1207 | |
| 1208 | EXPORT_SYMBOL(__break_lease); |
| 1209 | |
| 1210 | /** |
| 1211 | * lease_get_mtime |
| 1212 | * @inode: the inode |
| 1213 | * @time: pointer to a timespec which will contain the last modified time |
| 1214 | * |
| 1215 | * This is to force NFS clients to flush their caches for files with |
| 1216 | * exclusive leases. The justification is that if someone has an |
| 1217 | * exclusive lease, then they could be modifiying it. |
| 1218 | */ |
| 1219 | void lease_get_mtime(struct inode *inode, struct timespec *time) |
| 1220 | { |
| 1221 | struct file_lock *flock = inode->i_flock; |
| 1222 | if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK)) |
| 1223 | *time = current_fs_time(inode->i_sb); |
| 1224 | else |
| 1225 | *time = inode->i_mtime; |
| 1226 | } |
| 1227 | |
| 1228 | EXPORT_SYMBOL(lease_get_mtime); |
| 1229 | |
| 1230 | /** |
| 1231 | * fcntl_getlease - Enquire what lease is currently active |
| 1232 | * @filp: the file |
| 1233 | * |
| 1234 | * The value returned by this function will be one of |
| 1235 | * (if no lease break is pending): |
| 1236 | * |
| 1237 | * %F_RDLCK to indicate a shared lease is held. |
| 1238 | * |
| 1239 | * %F_WRLCK to indicate an exclusive lease is held. |
| 1240 | * |
| 1241 | * %F_UNLCK to indicate no lease is held. |
| 1242 | * |
| 1243 | * (if a lease break is pending): |
| 1244 | * |
| 1245 | * %F_RDLCK to indicate an exclusive lease needs to be |
| 1246 | * changed to a shared lease (or removed). |
| 1247 | * |
| 1248 | * %F_UNLCK to indicate the lease needs to be removed. |
| 1249 | * |
| 1250 | * XXX: sfr & willy disagree over whether F_INPROGRESS |
| 1251 | * should be returned to userspace. |
| 1252 | */ |
| 1253 | int fcntl_getlease(struct file *filp) |
| 1254 | { |
| 1255 | struct file_lock *fl; |
| 1256 | int type = F_UNLCK; |
| 1257 | |
| 1258 | lock_kernel(); |
| 1259 | time_out_leases(filp->f_dentry->d_inode); |
| 1260 | for (fl = filp->f_dentry->d_inode->i_flock; fl && IS_LEASE(fl); |
| 1261 | fl = fl->fl_next) { |
| 1262 | if (fl->fl_file == filp) { |
| 1263 | type = fl->fl_type & ~F_INPROGRESS; |
| 1264 | break; |
| 1265 | } |
| 1266 | } |
| 1267 | unlock_kernel(); |
| 1268 | return type; |
| 1269 | } |
| 1270 | |
| 1271 | /** |
| 1272 | * __setlease - sets a lease on an open file |
| 1273 | * @filp: file pointer |
| 1274 | * @arg: type of lease to obtain |
| 1275 | * @flp: input - file_lock to use, output - file_lock inserted |
| 1276 | * |
| 1277 | * The (input) flp->fl_lmops->fl_break function is required |
| 1278 | * by break_lease(). |
| 1279 | * |
| 1280 | * Called with kernel lock held. |
| 1281 | */ |
Adrian Bunk | 75c96f8 | 2005-05-05 16:16:09 -0700 | [diff] [blame] | 1282 | static int __setlease(struct file *filp, long arg, struct file_lock **flp) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1283 | { |
KAMBAROV, ZAUR | 7eaae28 | 2005-07-07 17:57:06 -0700 | [diff] [blame] | 1284 | struct file_lock *fl, **before, **my_before = NULL, *lease; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1285 | struct dentry *dentry = filp->f_dentry; |
| 1286 | struct inode *inode = dentry->d_inode; |
| 1287 | int error, rdlease_count = 0, wrlease_count = 0; |
| 1288 | |
| 1289 | time_out_leases(inode); |
| 1290 | |
| 1291 | error = -EINVAL; |
| 1292 | if (!flp || !(*flp) || !(*flp)->fl_lmops || !(*flp)->fl_lmops->fl_break) |
| 1293 | goto out; |
| 1294 | |
KAMBAROV, ZAUR | 7eaae28 | 2005-07-07 17:57:06 -0700 | [diff] [blame] | 1295 | lease = *flp; |
| 1296 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1297 | error = -EAGAIN; |
| 1298 | if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) |
| 1299 | goto out; |
| 1300 | if ((arg == F_WRLCK) |
| 1301 | && ((atomic_read(&dentry->d_count) > 1) |
| 1302 | || (atomic_read(&inode->i_count) > 1))) |
| 1303 | goto out; |
| 1304 | |
| 1305 | /* |
| 1306 | * At this point, we know that if there is an exclusive |
| 1307 | * lease on this file, then we hold it on this filp |
| 1308 | * (otherwise our open of this file would have blocked). |
| 1309 | * And if we are trying to acquire an exclusive lease, |
| 1310 | * then the file is not open by anyone (including us) |
| 1311 | * except for this filp. |
| 1312 | */ |
| 1313 | for (before = &inode->i_flock; |
| 1314 | ((fl = *before) != NULL) && IS_LEASE(fl); |
| 1315 | before = &fl->fl_next) { |
| 1316 | if (lease->fl_lmops->fl_mylease(fl, lease)) |
| 1317 | my_before = before; |
| 1318 | else if (fl->fl_type == (F_INPROGRESS | F_UNLCK)) |
| 1319 | /* |
| 1320 | * Someone is in the process of opening this |
| 1321 | * file for writing so we may not take an |
| 1322 | * exclusive lease on it. |
| 1323 | */ |
| 1324 | wrlease_count++; |
| 1325 | else |
| 1326 | rdlease_count++; |
| 1327 | } |
| 1328 | |
| 1329 | if ((arg == F_RDLCK && (wrlease_count > 0)) || |
| 1330 | (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0))) |
| 1331 | goto out; |
| 1332 | |
| 1333 | if (my_before != NULL) { |
| 1334 | error = lease->fl_lmops->fl_change(my_before, arg); |
| 1335 | goto out; |
| 1336 | } |
| 1337 | |
| 1338 | error = 0; |
| 1339 | if (arg == F_UNLCK) |
| 1340 | goto out; |
| 1341 | |
| 1342 | error = -EINVAL; |
| 1343 | if (!leases_enable) |
| 1344 | goto out; |
| 1345 | |
| 1346 | error = lease_alloc(filp, arg, &fl); |
| 1347 | if (error) |
| 1348 | goto out; |
| 1349 | |
| 1350 | locks_copy_lock(fl, lease); |
| 1351 | |
| 1352 | locks_insert_lock(before, fl); |
| 1353 | |
| 1354 | *flp = fl; |
| 1355 | out: |
| 1356 | return error; |
| 1357 | } |
| 1358 | |
| 1359 | /** |
| 1360 | * setlease - sets a lease on an open file |
| 1361 | * @filp: file pointer |
| 1362 | * @arg: type of lease to obtain |
| 1363 | * @lease: file_lock to use |
| 1364 | * |
| 1365 | * Call this to establish a lease on the file. |
| 1366 | * The fl_lmops fl_break function is required by break_lease |
| 1367 | */ |
| 1368 | |
| 1369 | int setlease(struct file *filp, long arg, struct file_lock **lease) |
| 1370 | { |
| 1371 | struct dentry *dentry = filp->f_dentry; |
| 1372 | struct inode *inode = dentry->d_inode; |
| 1373 | int error; |
| 1374 | |
| 1375 | if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) |
| 1376 | return -EACCES; |
| 1377 | if (!S_ISREG(inode->i_mode)) |
| 1378 | return -EINVAL; |
| 1379 | error = security_file_lock(filp, arg); |
| 1380 | if (error) |
| 1381 | return error; |
| 1382 | |
| 1383 | lock_kernel(); |
| 1384 | error = __setlease(filp, arg, lease); |
| 1385 | unlock_kernel(); |
| 1386 | |
| 1387 | return error; |
| 1388 | } |
| 1389 | |
| 1390 | EXPORT_SYMBOL(setlease); |
| 1391 | |
| 1392 | /** |
| 1393 | * fcntl_setlease - sets a lease on an open file |
| 1394 | * @fd: open file descriptor |
| 1395 | * @filp: file pointer |
| 1396 | * @arg: type of lease to obtain |
| 1397 | * |
| 1398 | * Call this fcntl to establish a lease on the file. |
| 1399 | * Note that you also need to call %F_SETSIG to |
| 1400 | * receive a signal when the lease is broken. |
| 1401 | */ |
| 1402 | int fcntl_setlease(unsigned int fd, struct file *filp, long arg) |
| 1403 | { |
| 1404 | struct file_lock fl, *flp = &fl; |
| 1405 | struct dentry *dentry = filp->f_dentry; |
| 1406 | struct inode *inode = dentry->d_inode; |
| 1407 | int error; |
| 1408 | |
| 1409 | if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) |
| 1410 | return -EACCES; |
| 1411 | if (!S_ISREG(inode->i_mode)) |
| 1412 | return -EINVAL; |
| 1413 | error = security_file_lock(filp, arg); |
| 1414 | if (error) |
| 1415 | return error; |
| 1416 | |
| 1417 | locks_init_lock(&fl); |
| 1418 | error = lease_init(filp, arg, &fl); |
| 1419 | if (error) |
| 1420 | return error; |
| 1421 | |
| 1422 | lock_kernel(); |
| 1423 | |
| 1424 | error = __setlease(filp, arg, &flp); |
| 1425 | if (error) |
| 1426 | goto out_unlock; |
| 1427 | |
| 1428 | error = fasync_helper(fd, filp, 1, &flp->fl_fasync); |
| 1429 | if (error < 0) { |
| 1430 | /* remove lease just inserted by __setlease */ |
| 1431 | flp->fl_type = F_UNLCK | F_INPROGRESS; |
| 1432 | flp->fl_break_time = jiffies- 10; |
| 1433 | time_out_leases(inode); |
| 1434 | goto out_unlock; |
| 1435 | } |
| 1436 | |
| 1437 | error = f_setown(filp, current->pid, 0); |
| 1438 | out_unlock: |
| 1439 | unlock_kernel(); |
| 1440 | return error; |
| 1441 | } |
| 1442 | |
| 1443 | /** |
| 1444 | * flock_lock_file_wait - Apply a FLOCK-style lock to a file |
| 1445 | * @filp: The file to apply the lock to |
| 1446 | * @fl: The lock to be applied |
| 1447 | * |
| 1448 | * Add a FLOCK style lock to a file. |
| 1449 | */ |
| 1450 | int flock_lock_file_wait(struct file *filp, struct file_lock *fl) |
| 1451 | { |
| 1452 | int error; |
| 1453 | might_sleep(); |
| 1454 | for (;;) { |
| 1455 | error = flock_lock_file(filp, fl); |
| 1456 | if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) |
| 1457 | break; |
| 1458 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); |
| 1459 | if (!error) |
| 1460 | continue; |
| 1461 | |
| 1462 | locks_delete_block(fl); |
| 1463 | break; |
| 1464 | } |
| 1465 | return error; |
| 1466 | } |
| 1467 | |
| 1468 | EXPORT_SYMBOL(flock_lock_file_wait); |
| 1469 | |
| 1470 | /** |
| 1471 | * sys_flock: - flock() system call. |
| 1472 | * @fd: the file descriptor to lock. |
| 1473 | * @cmd: the type of lock to apply. |
| 1474 | * |
| 1475 | * Apply a %FL_FLOCK style lock to an open file descriptor. |
| 1476 | * The @cmd can be one of |
| 1477 | * |
| 1478 | * %LOCK_SH -- a shared lock. |
| 1479 | * |
| 1480 | * %LOCK_EX -- an exclusive lock. |
| 1481 | * |
| 1482 | * %LOCK_UN -- remove an existing lock. |
| 1483 | * |
| 1484 | * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes. |
| 1485 | * |
| 1486 | * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other |
| 1487 | * processes read and write access respectively. |
| 1488 | */ |
| 1489 | asmlinkage long sys_flock(unsigned int fd, unsigned int cmd) |
| 1490 | { |
| 1491 | struct file *filp; |
| 1492 | struct file_lock *lock; |
| 1493 | int can_sleep, unlock; |
| 1494 | int error; |
| 1495 | |
| 1496 | error = -EBADF; |
| 1497 | filp = fget(fd); |
| 1498 | if (!filp) |
| 1499 | goto out; |
| 1500 | |
| 1501 | can_sleep = !(cmd & LOCK_NB); |
| 1502 | cmd &= ~LOCK_NB; |
| 1503 | unlock = (cmd == LOCK_UN); |
| 1504 | |
| 1505 | if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3)) |
| 1506 | goto out_putf; |
| 1507 | |
| 1508 | error = flock_make_lock(filp, &lock, cmd); |
| 1509 | if (error) |
| 1510 | goto out_putf; |
| 1511 | if (can_sleep) |
| 1512 | lock->fl_flags |= FL_SLEEP; |
| 1513 | |
| 1514 | error = security_file_lock(filp, cmd); |
| 1515 | if (error) |
| 1516 | goto out_free; |
| 1517 | |
| 1518 | if (filp->f_op && filp->f_op->flock) |
| 1519 | error = filp->f_op->flock(filp, |
| 1520 | (can_sleep) ? F_SETLKW : F_SETLK, |
| 1521 | lock); |
| 1522 | else |
| 1523 | error = flock_lock_file_wait(filp, lock); |
| 1524 | |
| 1525 | out_free: |
| 1526 | if (list_empty(&lock->fl_link)) { |
| 1527 | locks_free_lock(lock); |
| 1528 | } |
| 1529 | |
| 1530 | out_putf: |
| 1531 | fput(filp); |
| 1532 | out: |
| 1533 | return error; |
| 1534 | } |
| 1535 | |
| 1536 | /* Report the first existing lock that would conflict with l. |
| 1537 | * This implements the F_GETLK command of fcntl(). |
| 1538 | */ |
| 1539 | int fcntl_getlk(struct file *filp, struct flock __user *l) |
| 1540 | { |
| 1541 | struct file_lock *fl, file_lock; |
| 1542 | struct flock flock; |
| 1543 | int error; |
| 1544 | |
| 1545 | error = -EFAULT; |
| 1546 | if (copy_from_user(&flock, l, sizeof(flock))) |
| 1547 | goto out; |
| 1548 | error = -EINVAL; |
| 1549 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) |
| 1550 | goto out; |
| 1551 | |
| 1552 | error = flock_to_posix_lock(filp, &file_lock, &flock); |
| 1553 | if (error) |
| 1554 | goto out; |
| 1555 | |
| 1556 | if (filp->f_op && filp->f_op->lock) { |
| 1557 | error = filp->f_op->lock(filp, F_GETLK, &file_lock); |
Trond Myklebust | 80fec4c | 2005-06-22 17:16:31 +0000 | [diff] [blame] | 1558 | if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private) |
| 1559 | file_lock.fl_ops->fl_release_private(&file_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1560 | if (error < 0) |
| 1561 | goto out; |
| 1562 | else |
| 1563 | fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); |
| 1564 | } else { |
| 1565 | fl = posix_test_lock(filp, &file_lock); |
| 1566 | } |
| 1567 | |
| 1568 | flock.l_type = F_UNLCK; |
| 1569 | if (fl != NULL) { |
| 1570 | flock.l_pid = fl->fl_pid; |
| 1571 | #if BITS_PER_LONG == 32 |
| 1572 | /* |
| 1573 | * Make sure we can represent the posix lock via |
| 1574 | * legacy 32bit flock. |
| 1575 | */ |
| 1576 | error = -EOVERFLOW; |
| 1577 | if (fl->fl_start > OFFT_OFFSET_MAX) |
| 1578 | goto out; |
| 1579 | if ((fl->fl_end != OFFSET_MAX) |
| 1580 | && (fl->fl_end > OFFT_OFFSET_MAX)) |
| 1581 | goto out; |
| 1582 | #endif |
| 1583 | flock.l_start = fl->fl_start; |
| 1584 | flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : |
| 1585 | fl->fl_end - fl->fl_start + 1; |
| 1586 | flock.l_whence = 0; |
| 1587 | flock.l_type = fl->fl_type; |
| 1588 | } |
| 1589 | error = -EFAULT; |
| 1590 | if (!copy_to_user(l, &flock, sizeof(flock))) |
| 1591 | error = 0; |
| 1592 | out: |
| 1593 | return error; |
| 1594 | } |
| 1595 | |
| 1596 | /* Apply the lock described by l to an open file descriptor. |
| 1597 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). |
| 1598 | */ |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1599 | int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd, |
| 1600 | struct flock __user *l) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1601 | { |
| 1602 | struct file_lock *file_lock = locks_alloc_lock(); |
| 1603 | struct flock flock; |
| 1604 | struct inode *inode; |
| 1605 | int error; |
| 1606 | |
| 1607 | if (file_lock == NULL) |
| 1608 | return -ENOLCK; |
| 1609 | |
| 1610 | /* |
| 1611 | * This might block, so we do it before checking the inode. |
| 1612 | */ |
| 1613 | error = -EFAULT; |
| 1614 | if (copy_from_user(&flock, l, sizeof(flock))) |
| 1615 | goto out; |
| 1616 | |
| 1617 | inode = filp->f_dentry->d_inode; |
| 1618 | |
| 1619 | /* Don't allow mandatory locks on files that may be memory mapped |
| 1620 | * and shared. |
| 1621 | */ |
| 1622 | if (IS_MANDLOCK(inode) && |
| 1623 | (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && |
| 1624 | mapping_writably_mapped(filp->f_mapping)) { |
| 1625 | error = -EAGAIN; |
| 1626 | goto out; |
| 1627 | } |
| 1628 | |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1629 | again: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1630 | error = flock_to_posix_lock(filp, file_lock, &flock); |
| 1631 | if (error) |
| 1632 | goto out; |
| 1633 | if (cmd == F_SETLKW) { |
| 1634 | file_lock->fl_flags |= FL_SLEEP; |
| 1635 | } |
| 1636 | |
| 1637 | error = -EBADF; |
| 1638 | switch (flock.l_type) { |
| 1639 | case F_RDLCK: |
| 1640 | if (!(filp->f_mode & FMODE_READ)) |
| 1641 | goto out; |
| 1642 | break; |
| 1643 | case F_WRLCK: |
| 1644 | if (!(filp->f_mode & FMODE_WRITE)) |
| 1645 | goto out; |
| 1646 | break; |
| 1647 | case F_UNLCK: |
| 1648 | break; |
| 1649 | default: |
| 1650 | error = -EINVAL; |
| 1651 | goto out; |
| 1652 | } |
| 1653 | |
| 1654 | error = security_file_lock(filp, file_lock->fl_type); |
| 1655 | if (error) |
| 1656 | goto out; |
| 1657 | |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1658 | if (filp->f_op && filp->f_op->lock != NULL) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1659 | error = filp->f_op->lock(filp, cmd, file_lock); |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1660 | else { |
| 1661 | for (;;) { |
| 1662 | error = __posix_lock_file(inode, file_lock); |
| 1663 | if ((error != -EAGAIN) || (cmd == F_SETLK)) |
| 1664 | break; |
| 1665 | error = wait_event_interruptible(file_lock->fl_wait, |
| 1666 | !file_lock->fl_next); |
| 1667 | if (!error) |
| 1668 | continue; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1669 | |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1670 | locks_delete_block(file_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1671 | break; |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1672 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1673 | } |
| 1674 | |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1675 | /* |
| 1676 | * Attempt to detect a close/fcntl race and recover by |
| 1677 | * releasing the lock that was just acquired. |
| 1678 | */ |
| 1679 | if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) { |
| 1680 | flock.l_type = F_UNLCK; |
| 1681 | goto again; |
| 1682 | } |
| 1683 | |
| 1684 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1685 | locks_free_lock(file_lock); |
| 1686 | return error; |
| 1687 | } |
| 1688 | |
| 1689 | #if BITS_PER_LONG == 32 |
| 1690 | /* Report the first existing lock that would conflict with l. |
| 1691 | * This implements the F_GETLK command of fcntl(). |
| 1692 | */ |
| 1693 | int fcntl_getlk64(struct file *filp, struct flock64 __user *l) |
| 1694 | { |
| 1695 | struct file_lock *fl, file_lock; |
| 1696 | struct flock64 flock; |
| 1697 | int error; |
| 1698 | |
| 1699 | error = -EFAULT; |
| 1700 | if (copy_from_user(&flock, l, sizeof(flock))) |
| 1701 | goto out; |
| 1702 | error = -EINVAL; |
| 1703 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) |
| 1704 | goto out; |
| 1705 | |
| 1706 | error = flock64_to_posix_lock(filp, &file_lock, &flock); |
| 1707 | if (error) |
| 1708 | goto out; |
| 1709 | |
| 1710 | if (filp->f_op && filp->f_op->lock) { |
| 1711 | error = filp->f_op->lock(filp, F_GETLK, &file_lock); |
Trond Myklebust | 80fec4c | 2005-06-22 17:16:31 +0000 | [diff] [blame] | 1712 | if (file_lock.fl_ops && file_lock.fl_ops->fl_release_private) |
| 1713 | file_lock.fl_ops->fl_release_private(&file_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1714 | if (error < 0) |
| 1715 | goto out; |
| 1716 | else |
| 1717 | fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); |
| 1718 | } else { |
| 1719 | fl = posix_test_lock(filp, &file_lock); |
| 1720 | } |
| 1721 | |
| 1722 | flock.l_type = F_UNLCK; |
| 1723 | if (fl != NULL) { |
| 1724 | flock.l_pid = fl->fl_pid; |
| 1725 | flock.l_start = fl->fl_start; |
| 1726 | flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : |
| 1727 | fl->fl_end - fl->fl_start + 1; |
| 1728 | flock.l_whence = 0; |
| 1729 | flock.l_type = fl->fl_type; |
| 1730 | } |
| 1731 | error = -EFAULT; |
| 1732 | if (!copy_to_user(l, &flock, sizeof(flock))) |
| 1733 | error = 0; |
| 1734 | |
| 1735 | out: |
| 1736 | return error; |
| 1737 | } |
| 1738 | |
| 1739 | /* Apply the lock described by l to an open file descriptor. |
| 1740 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). |
| 1741 | */ |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1742 | int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, |
| 1743 | struct flock64 __user *l) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1744 | { |
| 1745 | struct file_lock *file_lock = locks_alloc_lock(); |
| 1746 | struct flock64 flock; |
| 1747 | struct inode *inode; |
| 1748 | int error; |
| 1749 | |
| 1750 | if (file_lock == NULL) |
| 1751 | return -ENOLCK; |
| 1752 | |
| 1753 | /* |
| 1754 | * This might block, so we do it before checking the inode. |
| 1755 | */ |
| 1756 | error = -EFAULT; |
| 1757 | if (copy_from_user(&flock, l, sizeof(flock))) |
| 1758 | goto out; |
| 1759 | |
| 1760 | inode = filp->f_dentry->d_inode; |
| 1761 | |
| 1762 | /* Don't allow mandatory locks on files that may be memory mapped |
| 1763 | * and shared. |
| 1764 | */ |
| 1765 | if (IS_MANDLOCK(inode) && |
| 1766 | (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && |
| 1767 | mapping_writably_mapped(filp->f_mapping)) { |
| 1768 | error = -EAGAIN; |
| 1769 | goto out; |
| 1770 | } |
| 1771 | |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1772 | again: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1773 | error = flock64_to_posix_lock(filp, file_lock, &flock); |
| 1774 | if (error) |
| 1775 | goto out; |
| 1776 | if (cmd == F_SETLKW64) { |
| 1777 | file_lock->fl_flags |= FL_SLEEP; |
| 1778 | } |
| 1779 | |
| 1780 | error = -EBADF; |
| 1781 | switch (flock.l_type) { |
| 1782 | case F_RDLCK: |
| 1783 | if (!(filp->f_mode & FMODE_READ)) |
| 1784 | goto out; |
| 1785 | break; |
| 1786 | case F_WRLCK: |
| 1787 | if (!(filp->f_mode & FMODE_WRITE)) |
| 1788 | goto out; |
| 1789 | break; |
| 1790 | case F_UNLCK: |
| 1791 | break; |
| 1792 | default: |
| 1793 | error = -EINVAL; |
| 1794 | goto out; |
| 1795 | } |
| 1796 | |
| 1797 | error = security_file_lock(filp, file_lock->fl_type); |
| 1798 | if (error) |
| 1799 | goto out; |
| 1800 | |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1801 | if (filp->f_op && filp->f_op->lock != NULL) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1802 | error = filp->f_op->lock(filp, cmd, file_lock); |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1803 | else { |
| 1804 | for (;;) { |
| 1805 | error = __posix_lock_file(inode, file_lock); |
| 1806 | if ((error != -EAGAIN) || (cmd == F_SETLK64)) |
| 1807 | break; |
| 1808 | error = wait_event_interruptible(file_lock->fl_wait, |
| 1809 | !file_lock->fl_next); |
| 1810 | if (!error) |
| 1811 | continue; |
| 1812 | |
| 1813 | locks_delete_block(file_lock); |
| 1814 | break; |
| 1815 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1816 | } |
| 1817 | |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1818 | /* |
| 1819 | * Attempt to detect a close/fcntl race and recover by |
| 1820 | * releasing the lock that was just acquired. |
| 1821 | */ |
| 1822 | if (!error && fcheck(fd) != filp && flock.l_type != F_UNLCK) { |
| 1823 | flock.l_type = F_UNLCK; |
| 1824 | goto again; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1825 | } |
| 1826 | |
| 1827 | out: |
| 1828 | locks_free_lock(file_lock); |
| 1829 | return error; |
| 1830 | } |
| 1831 | #endif /* BITS_PER_LONG == 32 */ |
| 1832 | |
| 1833 | /* |
| 1834 | * This function is called when the file is being removed |
| 1835 | * from the task's fd array. POSIX locks belonging to this task |
| 1836 | * are deleted at this time. |
| 1837 | */ |
| 1838 | void locks_remove_posix(struct file *filp, fl_owner_t owner) |
| 1839 | { |
| 1840 | struct file_lock lock, **before; |
| 1841 | |
| 1842 | /* |
| 1843 | * If there are no locks held on this file, we don't need to call |
| 1844 | * posix_lock_file(). Another process could be setting a lock on this |
| 1845 | * file at the same time, but we wouldn't remove that lock anyway. |
| 1846 | */ |
| 1847 | before = &filp->f_dentry->d_inode->i_flock; |
| 1848 | if (*before == NULL) |
| 1849 | return; |
| 1850 | |
| 1851 | lock.fl_type = F_UNLCK; |
| 1852 | lock.fl_flags = FL_POSIX; |
| 1853 | lock.fl_start = 0; |
| 1854 | lock.fl_end = OFFSET_MAX; |
| 1855 | lock.fl_owner = owner; |
| 1856 | lock.fl_pid = current->tgid; |
| 1857 | lock.fl_file = filp; |
| 1858 | lock.fl_ops = NULL; |
| 1859 | lock.fl_lmops = NULL; |
| 1860 | |
| 1861 | if (filp->f_op && filp->f_op->lock != NULL) { |
| 1862 | filp->f_op->lock(filp, F_SETLK, &lock); |
| 1863 | goto out; |
| 1864 | } |
| 1865 | |
| 1866 | /* Can't use posix_lock_file here; we need to remove it no matter |
| 1867 | * which pid we have. |
| 1868 | */ |
| 1869 | lock_kernel(); |
| 1870 | while (*before != NULL) { |
| 1871 | struct file_lock *fl = *before; |
| 1872 | if (IS_POSIX(fl) && posix_same_owner(fl, &lock)) { |
| 1873 | locks_delete_lock(before); |
| 1874 | continue; |
| 1875 | } |
| 1876 | before = &fl->fl_next; |
| 1877 | } |
| 1878 | unlock_kernel(); |
| 1879 | out: |
| 1880 | if (lock.fl_ops && lock.fl_ops->fl_release_private) |
| 1881 | lock.fl_ops->fl_release_private(&lock); |
| 1882 | } |
| 1883 | |
| 1884 | EXPORT_SYMBOL(locks_remove_posix); |
| 1885 | |
| 1886 | /* |
| 1887 | * This function is called on the last close of an open file. |
| 1888 | */ |
| 1889 | void locks_remove_flock(struct file *filp) |
| 1890 | { |
| 1891 | struct inode * inode = filp->f_dentry->d_inode; |
| 1892 | struct file_lock *fl; |
| 1893 | struct file_lock **before; |
| 1894 | |
| 1895 | if (!inode->i_flock) |
| 1896 | return; |
| 1897 | |
| 1898 | if (filp->f_op && filp->f_op->flock) { |
| 1899 | struct file_lock fl = { |
| 1900 | .fl_pid = current->tgid, |
| 1901 | .fl_file = filp, |
| 1902 | .fl_flags = FL_FLOCK, |
| 1903 | .fl_type = F_UNLCK, |
| 1904 | .fl_end = OFFSET_MAX, |
| 1905 | }; |
| 1906 | filp->f_op->flock(filp, F_SETLKW, &fl); |
Trond Myklebust | 80fec4c | 2005-06-22 17:16:31 +0000 | [diff] [blame] | 1907 | if (fl.fl_ops && fl.fl_ops->fl_release_private) |
| 1908 | fl.fl_ops->fl_release_private(&fl); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1909 | } |
| 1910 | |
| 1911 | lock_kernel(); |
| 1912 | before = &inode->i_flock; |
| 1913 | |
| 1914 | while ((fl = *before) != NULL) { |
| 1915 | if (fl->fl_file == filp) { |
Peter Staubach | c293621 | 2005-07-27 11:45:09 -0700 | [diff] [blame] | 1916 | if (IS_FLOCK(fl)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1917 | locks_delete_lock(before); |
| 1918 | continue; |
| 1919 | } |
| 1920 | if (IS_LEASE(fl)) { |
| 1921 | lease_modify(before, F_UNLCK); |
| 1922 | continue; |
| 1923 | } |
| 1924 | /* What? */ |
| 1925 | BUG(); |
| 1926 | } |
| 1927 | before = &fl->fl_next; |
| 1928 | } |
| 1929 | unlock_kernel(); |
| 1930 | } |
| 1931 | |
| 1932 | /** |
| 1933 | * posix_block_lock - blocks waiting for a file lock |
| 1934 | * @blocker: the lock which is blocking |
| 1935 | * @waiter: the lock which conflicts and has to wait |
| 1936 | * |
| 1937 | * lockd needs to block waiting for locks. |
| 1938 | */ |
| 1939 | void |
| 1940 | posix_block_lock(struct file_lock *blocker, struct file_lock *waiter) |
| 1941 | { |
| 1942 | locks_insert_block(blocker, waiter); |
| 1943 | } |
| 1944 | |
| 1945 | EXPORT_SYMBOL(posix_block_lock); |
| 1946 | |
| 1947 | /** |
| 1948 | * posix_unblock_lock - stop waiting for a file lock |
| 1949 | * @filp: how the file was opened |
| 1950 | * @waiter: the lock which was waiting |
| 1951 | * |
| 1952 | * lockd needs to block waiting for locks. |
| 1953 | */ |
| 1954 | void |
| 1955 | posix_unblock_lock(struct file *filp, struct file_lock *waiter) |
| 1956 | { |
| 1957 | /* |
| 1958 | * A remote machine may cancel the lock request after it's been |
| 1959 | * granted locally. If that happens, we need to delete the lock. |
| 1960 | */ |
| 1961 | lock_kernel(); |
| 1962 | if (waiter->fl_next) { |
| 1963 | __locks_delete_block(waiter); |
| 1964 | unlock_kernel(); |
| 1965 | } else { |
| 1966 | unlock_kernel(); |
| 1967 | waiter->fl_type = F_UNLCK; |
| 1968 | posix_lock_file(filp, waiter); |
| 1969 | } |
| 1970 | } |
| 1971 | |
| 1972 | EXPORT_SYMBOL(posix_unblock_lock); |
| 1973 | |
| 1974 | static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx) |
| 1975 | { |
| 1976 | struct inode *inode = NULL; |
| 1977 | |
| 1978 | if (fl->fl_file != NULL) |
| 1979 | inode = fl->fl_file->f_dentry->d_inode; |
| 1980 | |
| 1981 | out += sprintf(out, "%d:%s ", id, pfx); |
| 1982 | if (IS_POSIX(fl)) { |
| 1983 | out += sprintf(out, "%6s %s ", |
| 1984 | (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ", |
| 1985 | (inode == NULL) ? "*NOINODE*" : |
| 1986 | (IS_MANDLOCK(inode) && |
| 1987 | (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ? |
| 1988 | "MANDATORY" : "ADVISORY "); |
| 1989 | } else if (IS_FLOCK(fl)) { |
| 1990 | if (fl->fl_type & LOCK_MAND) { |
| 1991 | out += sprintf(out, "FLOCK MSNFS "); |
| 1992 | } else { |
| 1993 | out += sprintf(out, "FLOCK ADVISORY "); |
| 1994 | } |
| 1995 | } else if (IS_LEASE(fl)) { |
| 1996 | out += sprintf(out, "LEASE "); |
| 1997 | if (fl->fl_type & F_INPROGRESS) |
| 1998 | out += sprintf(out, "BREAKING "); |
| 1999 | else if (fl->fl_file) |
| 2000 | out += sprintf(out, "ACTIVE "); |
| 2001 | else |
| 2002 | out += sprintf(out, "BREAKER "); |
| 2003 | } else { |
| 2004 | out += sprintf(out, "UNKNOWN UNKNOWN "); |
| 2005 | } |
| 2006 | if (fl->fl_type & LOCK_MAND) { |
| 2007 | out += sprintf(out, "%s ", |
| 2008 | (fl->fl_type & LOCK_READ) |
| 2009 | ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " |
| 2010 | : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); |
| 2011 | } else { |
| 2012 | out += sprintf(out, "%s ", |
| 2013 | (fl->fl_type & F_INPROGRESS) |
| 2014 | ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ " |
| 2015 | : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ "); |
| 2016 | } |
| 2017 | if (inode) { |
| 2018 | #ifdef WE_CAN_BREAK_LSLK_NOW |
| 2019 | out += sprintf(out, "%d %s:%ld ", fl->fl_pid, |
| 2020 | inode->i_sb->s_id, inode->i_ino); |
| 2021 | #else |
| 2022 | /* userspace relies on this representation of dev_t ;-( */ |
| 2023 | out += sprintf(out, "%d %02x:%02x:%ld ", fl->fl_pid, |
| 2024 | MAJOR(inode->i_sb->s_dev), |
| 2025 | MINOR(inode->i_sb->s_dev), inode->i_ino); |
| 2026 | #endif |
| 2027 | } else { |
| 2028 | out += sprintf(out, "%d <none>:0 ", fl->fl_pid); |
| 2029 | } |
| 2030 | if (IS_POSIX(fl)) { |
| 2031 | if (fl->fl_end == OFFSET_MAX) |
| 2032 | out += sprintf(out, "%Ld EOF\n", fl->fl_start); |
| 2033 | else |
| 2034 | out += sprintf(out, "%Ld %Ld\n", fl->fl_start, |
| 2035 | fl->fl_end); |
| 2036 | } else { |
| 2037 | out += sprintf(out, "0 EOF\n"); |
| 2038 | } |
| 2039 | } |
| 2040 | |
| 2041 | static void move_lock_status(char **p, off_t* pos, off_t offset) |
| 2042 | { |
| 2043 | int len; |
| 2044 | len = strlen(*p); |
| 2045 | if(*pos >= offset) { |
| 2046 | /* the complete line is valid */ |
| 2047 | *p += len; |
| 2048 | *pos += len; |
| 2049 | return; |
| 2050 | } |
| 2051 | if(*pos+len > offset) { |
| 2052 | /* use the second part of the line */ |
| 2053 | int i = offset-*pos; |
| 2054 | memmove(*p,*p+i,len-i); |
| 2055 | *p += len-i; |
| 2056 | *pos += len; |
| 2057 | return; |
| 2058 | } |
| 2059 | /* discard the complete line */ |
| 2060 | *pos += len; |
| 2061 | } |
| 2062 | |
| 2063 | /** |
| 2064 | * get_locks_status - reports lock usage in /proc/locks |
| 2065 | * @buffer: address in userspace to write into |
| 2066 | * @start: ? |
| 2067 | * @offset: how far we are through the buffer |
| 2068 | * @length: how much to read |
| 2069 | */ |
| 2070 | |
| 2071 | int get_locks_status(char *buffer, char **start, off_t offset, int length) |
| 2072 | { |
| 2073 | struct list_head *tmp; |
| 2074 | char *q = buffer; |
| 2075 | off_t pos = 0; |
| 2076 | int i = 0; |
| 2077 | |
| 2078 | lock_kernel(); |
| 2079 | list_for_each(tmp, &file_lock_list) { |
| 2080 | struct list_head *btmp; |
| 2081 | struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); |
| 2082 | lock_get_status(q, fl, ++i, ""); |
| 2083 | move_lock_status(&q, &pos, offset); |
| 2084 | |
| 2085 | if(pos >= offset+length) |
| 2086 | goto done; |
| 2087 | |
| 2088 | list_for_each(btmp, &fl->fl_block) { |
| 2089 | struct file_lock *bfl = list_entry(btmp, |
| 2090 | struct file_lock, fl_block); |
| 2091 | lock_get_status(q, bfl, i, " ->"); |
| 2092 | move_lock_status(&q, &pos, offset); |
| 2093 | |
| 2094 | if(pos >= offset+length) |
| 2095 | goto done; |
| 2096 | } |
| 2097 | } |
| 2098 | done: |
| 2099 | unlock_kernel(); |
| 2100 | *start = buffer; |
| 2101 | if(q-buffer < length) |
| 2102 | return (q-buffer); |
| 2103 | return length; |
| 2104 | } |
| 2105 | |
| 2106 | /** |
| 2107 | * lock_may_read - checks that the region is free of locks |
| 2108 | * @inode: the inode that is being read |
| 2109 | * @start: the first byte to read |
| 2110 | * @len: the number of bytes to read |
| 2111 | * |
| 2112 | * Emulates Windows locking requirements. Whole-file |
| 2113 | * mandatory locks (share modes) can prohibit a read and |
| 2114 | * byte-range POSIX locks can prohibit a read if they overlap. |
| 2115 | * |
| 2116 | * N.B. this function is only ever called |
| 2117 | * from knfsd and ownership of locks is never checked. |
| 2118 | */ |
| 2119 | int lock_may_read(struct inode *inode, loff_t start, unsigned long len) |
| 2120 | { |
| 2121 | struct file_lock *fl; |
| 2122 | int result = 1; |
| 2123 | lock_kernel(); |
| 2124 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { |
| 2125 | if (IS_POSIX(fl)) { |
| 2126 | if (fl->fl_type == F_RDLCK) |
| 2127 | continue; |
| 2128 | if ((fl->fl_end < start) || (fl->fl_start > (start + len))) |
| 2129 | continue; |
| 2130 | } else if (IS_FLOCK(fl)) { |
| 2131 | if (!(fl->fl_type & LOCK_MAND)) |
| 2132 | continue; |
| 2133 | if (fl->fl_type & LOCK_READ) |
| 2134 | continue; |
| 2135 | } else |
| 2136 | continue; |
| 2137 | result = 0; |
| 2138 | break; |
| 2139 | } |
| 2140 | unlock_kernel(); |
| 2141 | return result; |
| 2142 | } |
| 2143 | |
| 2144 | EXPORT_SYMBOL(lock_may_read); |
| 2145 | |
| 2146 | /** |
| 2147 | * lock_may_write - checks that the region is free of locks |
| 2148 | * @inode: the inode that is being written |
| 2149 | * @start: the first byte to write |
| 2150 | * @len: the number of bytes to write |
| 2151 | * |
| 2152 | * Emulates Windows locking requirements. Whole-file |
| 2153 | * mandatory locks (share modes) can prohibit a write and |
| 2154 | * byte-range POSIX locks can prohibit a write if they overlap. |
| 2155 | * |
| 2156 | * N.B. this function is only ever called |
| 2157 | * from knfsd and ownership of locks is never checked. |
| 2158 | */ |
| 2159 | int lock_may_write(struct inode *inode, loff_t start, unsigned long len) |
| 2160 | { |
| 2161 | struct file_lock *fl; |
| 2162 | int result = 1; |
| 2163 | lock_kernel(); |
| 2164 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { |
| 2165 | if (IS_POSIX(fl)) { |
| 2166 | if ((fl->fl_end < start) || (fl->fl_start > (start + len))) |
| 2167 | continue; |
| 2168 | } else if (IS_FLOCK(fl)) { |
| 2169 | if (!(fl->fl_type & LOCK_MAND)) |
| 2170 | continue; |
| 2171 | if (fl->fl_type & LOCK_WRITE) |
| 2172 | continue; |
| 2173 | } else |
| 2174 | continue; |
| 2175 | result = 0; |
| 2176 | break; |
| 2177 | } |
| 2178 | unlock_kernel(); |
| 2179 | return result; |
| 2180 | } |
| 2181 | |
| 2182 | EXPORT_SYMBOL(lock_may_write); |
| 2183 | |
| 2184 | static inline void __steal_locks(struct file *file, fl_owner_t from) |
| 2185 | { |
| 2186 | struct inode *inode = file->f_dentry->d_inode; |
| 2187 | struct file_lock *fl = inode->i_flock; |
| 2188 | |
| 2189 | while (fl) { |
| 2190 | if (fl->fl_file == file && fl->fl_owner == from) |
| 2191 | fl->fl_owner = current->files; |
| 2192 | fl = fl->fl_next; |
| 2193 | } |
| 2194 | } |
| 2195 | |
| 2196 | /* When getting ready for executing a binary, we make sure that current |
| 2197 | * has a files_struct on its own. Before dropping the old files_struct, |
| 2198 | * we take over ownership of all locks for all file descriptors we own. |
| 2199 | * Note that we may accidentally steal a lock for a file that a sibling |
| 2200 | * has created since the unshare_files() call. |
| 2201 | */ |
| 2202 | void steal_locks(fl_owner_t from) |
| 2203 | { |
| 2204 | struct files_struct *files = current->files; |
| 2205 | int i, j; |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 2206 | struct fdtable *fdt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2207 | |
| 2208 | if (from == files) |
| 2209 | return; |
| 2210 | |
| 2211 | lock_kernel(); |
| 2212 | j = 0; |
Dipankar Sarma | 4fb3a53 | 2005-09-16 19:28:13 -0700 | [diff] [blame] | 2213 | rcu_read_lock(); |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 2214 | fdt = files_fdtable(files); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2215 | for (;;) { |
| 2216 | unsigned long set; |
| 2217 | i = j * __NFDBITS; |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 2218 | if (i >= fdt->max_fdset || i >= fdt->max_fds) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2219 | break; |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 2220 | set = fdt->open_fds->fds_bits[j++]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2221 | while (set) { |
| 2222 | if (set & 1) { |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 2223 | struct file *file = fdt->fd[i]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2224 | if (file) |
| 2225 | __steal_locks(file, from); |
| 2226 | } |
| 2227 | i++; |
| 2228 | set >>= 1; |
| 2229 | } |
| 2230 | } |
Dipankar Sarma | 4fb3a53 | 2005-09-16 19:28:13 -0700 | [diff] [blame] | 2231 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2232 | unlock_kernel(); |
| 2233 | } |
| 2234 | EXPORT_SYMBOL(steal_locks); |
| 2235 | |
| 2236 | static int __init filelock_init(void) |
| 2237 | { |
| 2238 | filelock_cache = kmem_cache_create("file_lock_cache", |
| 2239 | sizeof(struct file_lock), 0, SLAB_PANIC, |
| 2240 | init_once, NULL); |
| 2241 | return 0; |
| 2242 | } |
| 2243 | |
| 2244 | core_initcall(filelock_init); |