| 1 | /* $NetBSD: vfs_trans.c,v 1.34 2015/08/24 22:50:32 pooka Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2007 The NetBSD Foundation, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * This code is derived from software contributed to The NetBSD Foundation |
| 8 | * by Juergen Hannken-Illjes. |
| 9 | * |
| 10 | * Redistribution and use in source and binary forms, with or without |
| 11 | * modification, are permitted provided that the following conditions |
| 12 | * are met: |
| 13 | * 1. Redistributions of source code must retain the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * |
| 19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 29 | * POSSIBILITY OF SUCH DAMAGE. |
| 30 | */ |
| 31 | |
| 32 | #include <sys/cdefs.h> |
| 33 | __KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,v 1.34 2015/08/24 22:50:32 pooka Exp $" ); |
| 34 | |
| 35 | /* |
| 36 | * File system transaction operations. |
| 37 | */ |
| 38 | |
| 39 | #ifdef _KERNEL_OPT |
| 40 | #include "opt_ddb.h" |
| 41 | #endif |
| 42 | |
| 43 | #include <sys/param.h> |
| 44 | #include <sys/systm.h> |
| 45 | #include <sys/atomic.h> |
| 46 | #include <sys/buf.h> |
| 47 | #include <sys/kmem.h> |
| 48 | #include <sys/mount.h> |
| 49 | #include <sys/pserialize.h> |
| 50 | #include <sys/vnode.h> |
| 51 | #define _FSTRANS_API_PRIVATE |
| 52 | #include <sys/fstrans.h> |
| 53 | #include <sys/proc.h> |
| 54 | |
| 55 | #include <miscfs/specfs/specdev.h> |
| 56 | |
| 57 | struct fscow_handler { |
| 58 | LIST_ENTRY(fscow_handler) ch_list; |
| 59 | int (*ch_func)(void *, struct buf *, bool); |
| 60 | void *ch_arg; |
| 61 | }; |
| 62 | struct fstrans_lwp_info { |
| 63 | struct fstrans_lwp_info *fli_succ; |
| 64 | struct lwp *fli_self; |
| 65 | struct mount *fli_mount; |
| 66 | int fli_trans_cnt; |
| 67 | int fli_cow_cnt; |
| 68 | enum fstrans_lock_type fli_lock_type; |
| 69 | LIST_ENTRY(fstrans_lwp_info) fli_list; |
| 70 | }; |
| 71 | struct fstrans_mount_info { |
| 72 | enum fstrans_state fmi_state; |
| 73 | unsigned int fmi_ref_cnt; |
| 74 | bool fmi_cow_change; |
| 75 | LIST_HEAD(, fscow_handler) fmi_cow_handler; |
| 76 | }; |
| 77 | |
| 78 | static specificdata_key_t lwp_data_key; /* Our specific data key. */ |
| 79 | static kmutex_t vfs_suspend_lock; /* Serialize suspensions. */ |
| 80 | static kmutex_t fstrans_lock; /* Fstrans big lock. */ |
| 81 | static kcondvar_t fstrans_state_cv; /* Fstrans or cow state changed. */ |
| 82 | static kcondvar_t fstrans_count_cv; /* Fstrans or cow count changed. */ |
| 83 | static pserialize_t fstrans_psz; /* Pserialize state. */ |
| 84 | static LIST_HEAD(fstrans_lwp_head, fstrans_lwp_info) fstrans_fli_head; |
| 85 | /* List of all fstrans_lwp_info. */ |
| 86 | |
| 87 | static void fstrans_lwp_dtor(void *); |
| 88 | static void fstrans_mount_dtor(struct mount *); |
| 89 | static struct fstrans_lwp_info *fstrans_get_lwp_info(struct mount *, bool); |
| 90 | static bool grant_lock(const enum fstrans_state, const enum fstrans_lock_type); |
| 91 | static bool state_change_done(const struct mount *); |
| 92 | static bool cow_state_change_done(const struct mount *); |
| 93 | static void cow_change_enter(const struct mount *); |
| 94 | static void cow_change_done(const struct mount *); |
| 95 | |
| 96 | /* |
| 97 | * Initialize. |
| 98 | */ |
| 99 | void |
| 100 | fstrans_init(void) |
| 101 | { |
| 102 | int error __diagused; |
| 103 | |
| 104 | error = lwp_specific_key_create(&lwp_data_key, fstrans_lwp_dtor); |
| 105 | KASSERT(error == 0); |
| 106 | |
| 107 | mutex_init(&vfs_suspend_lock, MUTEX_DEFAULT, IPL_NONE); |
| 108 | mutex_init(&fstrans_lock, MUTEX_DEFAULT, IPL_NONE); |
| 109 | cv_init(&fstrans_state_cv, "fstchg" ); |
| 110 | cv_init(&fstrans_count_cv, "fstcnt" ); |
| 111 | fstrans_psz = pserialize_create(); |
| 112 | LIST_INIT(&fstrans_fli_head); |
| 113 | } |
| 114 | |
| 115 | /* |
| 116 | * Deallocate lwp state. |
| 117 | */ |
| 118 | static void |
| 119 | fstrans_lwp_dtor(void *arg) |
| 120 | { |
| 121 | struct fstrans_lwp_info *fli, *fli_next; |
| 122 | |
| 123 | for (fli = arg; fli; fli = fli_next) { |
| 124 | KASSERT(fli->fli_trans_cnt == 0); |
| 125 | KASSERT(fli->fli_cow_cnt == 0); |
| 126 | if (fli->fli_mount != NULL) |
| 127 | fstrans_mount_dtor(fli->fli_mount); |
| 128 | fli_next = fli->fli_succ; |
| 129 | fli->fli_mount = NULL; |
| 130 | membar_sync(); |
| 131 | fli->fli_self = NULL; |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | /* |
| 136 | * Dereference mount state. |
| 137 | */ |
| 138 | static void |
| 139 | fstrans_mount_dtor(struct mount *mp) |
| 140 | { |
| 141 | struct fstrans_mount_info *fmi; |
| 142 | |
| 143 | fmi = mp->mnt_transinfo; |
| 144 | if (atomic_dec_uint_nv(&fmi->fmi_ref_cnt) > 0) |
| 145 | return; |
| 146 | |
| 147 | KASSERT(fmi->fmi_state == FSTRANS_NORMAL); |
| 148 | KASSERT(LIST_FIRST(&fmi->fmi_cow_handler) == NULL); |
| 149 | |
| 150 | kmem_free(fmi, sizeof(*fmi)); |
| 151 | mp->mnt_iflag &= ~IMNT_HAS_TRANS; |
| 152 | mp->mnt_transinfo = NULL; |
| 153 | |
| 154 | vfs_destroy(mp); |
| 155 | } |
| 156 | |
| 157 | /* |
| 158 | * Allocate mount state. |
| 159 | */ |
| 160 | int |
| 161 | fstrans_mount(struct mount *mp) |
| 162 | { |
| 163 | int error; |
| 164 | struct fstrans_mount_info *newfmi; |
| 165 | |
| 166 | error = vfs_busy(mp, NULL); |
| 167 | if (error) |
| 168 | return error; |
| 169 | newfmi = kmem_alloc(sizeof(*newfmi), KM_SLEEP); |
| 170 | newfmi->fmi_state = FSTRANS_NORMAL; |
| 171 | newfmi->fmi_ref_cnt = 1; |
| 172 | LIST_INIT(&newfmi->fmi_cow_handler); |
| 173 | newfmi->fmi_cow_change = false; |
| 174 | |
| 175 | mp->mnt_transinfo = newfmi; |
| 176 | mp->mnt_iflag |= IMNT_HAS_TRANS; |
| 177 | |
| 178 | vfs_unbusy(mp, true, NULL); |
| 179 | |
| 180 | return 0; |
| 181 | } |
| 182 | |
| 183 | /* |
| 184 | * Deallocate mount state. |
| 185 | */ |
| 186 | void |
| 187 | fstrans_unmount(struct mount *mp) |
| 188 | { |
| 189 | |
| 190 | KASSERT(mp->mnt_transinfo != NULL); |
| 191 | |
| 192 | fstrans_mount_dtor(mp); |
| 193 | } |
| 194 | |
| 195 | /* |
| 196 | * Retrieve the per lwp info for this mount allocating if necessary. |
| 197 | */ |
| 198 | static struct fstrans_lwp_info * |
| 199 | fstrans_get_lwp_info(struct mount *mp, bool do_alloc) |
| 200 | { |
| 201 | struct fstrans_lwp_info *fli, *res; |
| 202 | struct fstrans_mount_info *fmi; |
| 203 | |
| 204 | /* |
| 205 | * Scan our list for a match clearing entries whose mount is gone. |
| 206 | */ |
| 207 | res = NULL; |
| 208 | for (fli = lwp_getspecific(lwp_data_key); fli; fli = fli->fli_succ) { |
| 209 | if (fli->fli_mount == mp) { |
| 210 | KASSERT(res == NULL); |
| 211 | res = fli; |
| 212 | } else if (fli->fli_mount != NULL && |
| 213 | (fli->fli_mount->mnt_iflag & IMNT_GONE) != 0 && |
| 214 | fli->fli_trans_cnt == 0 && fli->fli_cow_cnt == 0) { |
| 215 | fstrans_mount_dtor(fli->fli_mount); |
| 216 | fli->fli_mount = NULL; |
| 217 | } |
| 218 | } |
| 219 | if (__predict_true(res != NULL)) |
| 220 | return res; |
| 221 | |
| 222 | if (! do_alloc) |
| 223 | return NULL; |
| 224 | |
| 225 | /* |
| 226 | * Try to reuse a cleared entry or allocate a new one. |
| 227 | */ |
| 228 | for (fli = lwp_getspecific(lwp_data_key); fli; fli = fli->fli_succ) { |
| 229 | if (fli->fli_mount == NULL) { |
| 230 | KASSERT(fli->fli_trans_cnt == 0); |
| 231 | KASSERT(fli->fli_cow_cnt == 0); |
| 232 | break; |
| 233 | } |
| 234 | } |
| 235 | if (fli == NULL) { |
| 236 | mutex_enter(&fstrans_lock); |
| 237 | LIST_FOREACH(fli, &fstrans_fli_head, fli_list) { |
| 238 | if (fli->fli_self == NULL) { |
| 239 | KASSERT(fli->fli_trans_cnt == 0); |
| 240 | KASSERT(fli->fli_cow_cnt == 0); |
| 241 | fli->fli_self = curlwp; |
| 242 | fli->fli_succ = lwp_getspecific(lwp_data_key); |
| 243 | lwp_setspecific(lwp_data_key, fli); |
| 244 | break; |
| 245 | } |
| 246 | } |
| 247 | mutex_exit(&fstrans_lock); |
| 248 | } |
| 249 | if (fli == NULL) { |
| 250 | fli = kmem_alloc(sizeof(*fli), KM_SLEEP); |
| 251 | mutex_enter(&fstrans_lock); |
| 252 | memset(fli, 0, sizeof(*fli)); |
| 253 | fli->fli_self = curlwp; |
| 254 | LIST_INSERT_HEAD(&fstrans_fli_head, fli, fli_list); |
| 255 | mutex_exit(&fstrans_lock); |
| 256 | fli->fli_succ = lwp_getspecific(lwp_data_key); |
| 257 | lwp_setspecific(lwp_data_key, fli); |
| 258 | } |
| 259 | |
| 260 | /* |
| 261 | * Attach the entry to the mount. |
| 262 | */ |
| 263 | fmi = mp->mnt_transinfo; |
| 264 | fli->fli_mount = mp; |
| 265 | atomic_inc_uint(&fmi->fmi_ref_cnt); |
| 266 | |
| 267 | return fli; |
| 268 | } |
| 269 | |
| 270 | /* |
| 271 | * Check if this lock type is granted at this state. |
| 272 | */ |
| 273 | static bool |
| 274 | grant_lock(const enum fstrans_state state, const enum fstrans_lock_type type) |
| 275 | { |
| 276 | |
| 277 | if (__predict_true(state == FSTRANS_NORMAL)) |
| 278 | return true; |
| 279 | if (type == FSTRANS_EXCL) |
| 280 | return true; |
| 281 | if (state == FSTRANS_SUSPENDING && type == FSTRANS_LAZY) |
| 282 | return true; |
| 283 | |
| 284 | return false; |
| 285 | } |
| 286 | |
| 287 | /* |
| 288 | * Start a transaction. If this thread already has a transaction on this |
| 289 | * file system increment the reference counter. |
| 290 | */ |
| 291 | int |
| 292 | _fstrans_start(struct mount *mp, enum fstrans_lock_type lock_type, int wait) |
| 293 | { |
| 294 | int s; |
| 295 | struct fstrans_lwp_info *fli; |
| 296 | struct fstrans_mount_info *fmi; |
| 297 | |
| 298 | ASSERT_SLEEPABLE(); |
| 299 | |
| 300 | if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
| 301 | return 0; |
| 302 | |
| 303 | fli = fstrans_get_lwp_info(mp, true); |
| 304 | |
| 305 | if (fli->fli_trans_cnt > 0) { |
| 306 | KASSERT(lock_type != FSTRANS_EXCL); |
| 307 | fli->fli_trans_cnt += 1; |
| 308 | |
| 309 | return 0; |
| 310 | } |
| 311 | |
| 312 | s = pserialize_read_enter(); |
| 313 | fmi = mp->mnt_transinfo; |
| 314 | if (__predict_true(grant_lock(fmi->fmi_state, lock_type))) { |
| 315 | fli->fli_trans_cnt = 1; |
| 316 | fli->fli_lock_type = lock_type; |
| 317 | pserialize_read_exit(s); |
| 318 | |
| 319 | return 0; |
| 320 | } |
| 321 | pserialize_read_exit(s); |
| 322 | |
| 323 | if (! wait) |
| 324 | return EBUSY; |
| 325 | |
| 326 | mutex_enter(&fstrans_lock); |
| 327 | while (! grant_lock(fmi->fmi_state, lock_type)) |
| 328 | cv_wait(&fstrans_state_cv, &fstrans_lock); |
| 329 | fli->fli_trans_cnt = 1; |
| 330 | fli->fli_lock_type = lock_type; |
| 331 | mutex_exit(&fstrans_lock); |
| 332 | |
| 333 | return 0; |
| 334 | } |
| 335 | |
| 336 | /* |
| 337 | * Finish a transaction. |
| 338 | */ |
| 339 | void |
| 340 | fstrans_done(struct mount *mp) |
| 341 | { |
| 342 | int s; |
| 343 | struct fstrans_lwp_info *fli; |
| 344 | struct fstrans_mount_info *fmi; |
| 345 | |
| 346 | if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
| 347 | return; |
| 348 | |
| 349 | fli = fstrans_get_lwp_info(mp, false); |
| 350 | KASSERT(fli != NULL); |
| 351 | KASSERT(fli->fli_trans_cnt > 0); |
| 352 | |
| 353 | if (fli->fli_trans_cnt > 1) { |
| 354 | fli->fli_trans_cnt -= 1; |
| 355 | |
| 356 | return; |
| 357 | } |
| 358 | |
| 359 | s = pserialize_read_enter(); |
| 360 | fmi = mp->mnt_transinfo; |
| 361 | if (__predict_true(fmi->fmi_state == FSTRANS_NORMAL)) { |
| 362 | fli->fli_trans_cnt = 0; |
| 363 | pserialize_read_exit(s); |
| 364 | |
| 365 | return; |
| 366 | } |
| 367 | pserialize_read_exit(s); |
| 368 | |
| 369 | mutex_enter(&fstrans_lock); |
| 370 | fli->fli_trans_cnt = 0; |
| 371 | cv_signal(&fstrans_count_cv); |
| 372 | mutex_exit(&fstrans_lock); |
| 373 | } |
| 374 | |
| 375 | /* |
| 376 | * Check if this thread has an exclusive lock. |
| 377 | */ |
| 378 | int |
| 379 | fstrans_is_owner(struct mount *mp) |
| 380 | { |
| 381 | struct fstrans_lwp_info *fli; |
| 382 | |
| 383 | if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
| 384 | return 0; |
| 385 | |
| 386 | fli = fstrans_get_lwp_info(mp, false); |
| 387 | if (fli == NULL || fli->fli_trans_cnt == 0) |
| 388 | return 0; |
| 389 | |
| 390 | KASSERT(fli->fli_mount == mp); |
| 391 | KASSERT(fli->fli_trans_cnt > 0); |
| 392 | |
| 393 | return (fli->fli_lock_type == FSTRANS_EXCL); |
| 394 | } |
| 395 | |
| 396 | /* |
| 397 | * True, if no thread is in a transaction not granted at the current state. |
| 398 | */ |
| 399 | static bool |
| 400 | state_change_done(const struct mount *mp) |
| 401 | { |
| 402 | struct fstrans_lwp_info *fli; |
| 403 | struct fstrans_mount_info *fmi; |
| 404 | |
| 405 | KASSERT(mutex_owned(&fstrans_lock)); |
| 406 | |
| 407 | fmi = mp->mnt_transinfo; |
| 408 | LIST_FOREACH(fli, &fstrans_fli_head, fli_list) { |
| 409 | if (fli->fli_mount != mp) |
| 410 | continue; |
| 411 | if (fli->fli_trans_cnt == 0) |
| 412 | continue; |
| 413 | if (grant_lock(fmi->fmi_state, fli->fli_lock_type)) |
| 414 | continue; |
| 415 | |
| 416 | return false; |
| 417 | } |
| 418 | |
| 419 | return true; |
| 420 | } |
| 421 | |
| 422 | /* |
| 423 | * Set new file system state. |
| 424 | */ |
| 425 | int |
| 426 | fstrans_setstate(struct mount *mp, enum fstrans_state new_state) |
| 427 | { |
| 428 | int error; |
| 429 | enum fstrans_state old_state; |
| 430 | struct fstrans_mount_info *fmi; |
| 431 | |
| 432 | fmi = mp->mnt_transinfo; |
| 433 | old_state = fmi->fmi_state; |
| 434 | if (old_state == new_state) |
| 435 | return 0; |
| 436 | |
| 437 | mutex_enter(&fstrans_lock); |
| 438 | fmi->fmi_state = new_state; |
| 439 | pserialize_perform(fstrans_psz); |
| 440 | |
| 441 | /* |
| 442 | * All threads see the new state now. |
| 443 | * Wait for transactions invalid at this state to leave. |
| 444 | */ |
| 445 | error = 0; |
| 446 | while (! state_change_done(mp)) { |
| 447 | error = cv_wait_sig(&fstrans_count_cv, &fstrans_lock); |
| 448 | if (error) { |
| 449 | new_state = fmi->fmi_state = FSTRANS_NORMAL; |
| 450 | break; |
| 451 | } |
| 452 | } |
| 453 | cv_broadcast(&fstrans_state_cv); |
| 454 | mutex_exit(&fstrans_lock); |
| 455 | |
| 456 | if (old_state != new_state) { |
| 457 | if (old_state == FSTRANS_NORMAL) |
| 458 | fstrans_start(mp, FSTRANS_EXCL); |
| 459 | if (new_state == FSTRANS_NORMAL) |
| 460 | fstrans_done(mp); |
| 461 | } |
| 462 | |
| 463 | return error; |
| 464 | } |
| 465 | |
| 466 | /* |
| 467 | * Get current file system state. |
| 468 | */ |
| 469 | enum fstrans_state |
| 470 | fstrans_getstate(struct mount *mp) |
| 471 | { |
| 472 | struct fstrans_mount_info *fmi; |
| 473 | |
| 474 | fmi = mp->mnt_transinfo; |
| 475 | KASSERT(fmi != NULL); |
| 476 | |
| 477 | return fmi->fmi_state; |
| 478 | } |
| 479 | |
| 480 | /* |
| 481 | * Request a filesystem to suspend all operations. |
| 482 | */ |
| 483 | int |
| 484 | vfs_suspend(struct mount *mp, int nowait) |
| 485 | { |
| 486 | int error; |
| 487 | |
| 488 | if (nowait) { |
| 489 | if (!mutex_tryenter(&vfs_suspend_lock)) |
| 490 | return EWOULDBLOCK; |
| 491 | } else |
| 492 | mutex_enter(&vfs_suspend_lock); |
| 493 | |
| 494 | mutex_enter(&syncer_mutex); |
| 495 | if ((error = VFS_SUSPENDCTL(mp, SUSPEND_SUSPEND)) != 0) { |
| 496 | mutex_exit(&syncer_mutex); |
| 497 | mutex_exit(&vfs_suspend_lock); |
| 498 | } |
| 499 | |
| 500 | return error; |
| 501 | } |
| 502 | |
| 503 | /* |
| 504 | * Request a filesystem to resume all operations. |
| 505 | */ |
| 506 | void |
| 507 | vfs_resume(struct mount *mp) |
| 508 | { |
| 509 | |
| 510 | VFS_SUSPENDCTL(mp, SUSPEND_RESUME); |
| 511 | mutex_exit(&syncer_mutex); |
| 512 | mutex_exit(&vfs_suspend_lock); |
| 513 | } |
| 514 | |
| 515 | |
| 516 | /* |
| 517 | * True, if no thread is running a cow handler. |
| 518 | */ |
| 519 | static bool |
| 520 | cow_state_change_done(const struct mount *mp) |
| 521 | { |
| 522 | struct fstrans_lwp_info *fli; |
| 523 | struct fstrans_mount_info *fmi __diagused; |
| 524 | |
| 525 | fmi = mp->mnt_transinfo; |
| 526 | |
| 527 | KASSERT(mutex_owned(&fstrans_lock)); |
| 528 | KASSERT(fmi->fmi_cow_change); |
| 529 | |
| 530 | LIST_FOREACH(fli, &fstrans_fli_head, fli_list) { |
| 531 | if (fli->fli_mount != mp) |
| 532 | continue; |
| 533 | if (fli->fli_cow_cnt == 0) |
| 534 | continue; |
| 535 | |
| 536 | return false; |
| 537 | } |
| 538 | |
| 539 | return true; |
| 540 | } |
| 541 | |
| 542 | /* |
| 543 | * Prepare for changing this mounts cow list. |
| 544 | * Returns with fstrans_lock locked. |
| 545 | */ |
| 546 | static void |
| 547 | cow_change_enter(const struct mount *mp) |
| 548 | { |
| 549 | struct fstrans_mount_info *fmi; |
| 550 | |
| 551 | fmi = mp->mnt_transinfo; |
| 552 | |
| 553 | mutex_enter(&fstrans_lock); |
| 554 | |
| 555 | /* |
| 556 | * Wait for other threads changing the list. |
| 557 | */ |
| 558 | while (fmi->fmi_cow_change) |
| 559 | cv_wait(&fstrans_state_cv, &fstrans_lock); |
| 560 | |
| 561 | /* |
| 562 | * Wait until all threads are aware of a state change. |
| 563 | */ |
| 564 | fmi->fmi_cow_change = true; |
| 565 | pserialize_perform(fstrans_psz); |
| 566 | |
| 567 | while (! cow_state_change_done(mp)) |
| 568 | cv_wait(&fstrans_count_cv, &fstrans_lock); |
| 569 | } |
| 570 | |
| 571 | /* |
| 572 | * Done changing this mounts cow list. |
| 573 | */ |
| 574 | static void |
| 575 | cow_change_done(const struct mount *mp) |
| 576 | { |
| 577 | struct fstrans_mount_info *fmi; |
| 578 | |
| 579 | KASSERT(mutex_owned(&fstrans_lock)); |
| 580 | |
| 581 | fmi = mp->mnt_transinfo; |
| 582 | |
| 583 | fmi->fmi_cow_change = false; |
| 584 | pserialize_perform(fstrans_psz); |
| 585 | |
| 586 | cv_broadcast(&fstrans_state_cv); |
| 587 | |
| 588 | mutex_exit(&fstrans_lock); |
| 589 | } |
| 590 | |
| 591 | /* |
| 592 | * Add a handler to this mount. |
| 593 | */ |
| 594 | int |
| 595 | fscow_establish(struct mount *mp, int (*func)(void *, struct buf *, bool), |
| 596 | void *arg) |
| 597 | { |
| 598 | struct fstrans_mount_info *fmi; |
| 599 | struct fscow_handler *newch; |
| 600 | |
| 601 | if ((mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
| 602 | return EINVAL; |
| 603 | |
| 604 | fmi = mp->mnt_transinfo; |
| 605 | KASSERT(fmi != NULL); |
| 606 | |
| 607 | newch = kmem_alloc(sizeof(*newch), KM_SLEEP); |
| 608 | newch->ch_func = func; |
| 609 | newch->ch_arg = arg; |
| 610 | |
| 611 | cow_change_enter(mp); |
| 612 | LIST_INSERT_HEAD(&fmi->fmi_cow_handler, newch, ch_list); |
| 613 | cow_change_done(mp); |
| 614 | |
| 615 | return 0; |
| 616 | } |
| 617 | |
| 618 | /* |
| 619 | * Remove a handler from this mount. |
| 620 | */ |
| 621 | int |
| 622 | fscow_disestablish(struct mount *mp, int (*func)(void *, struct buf *, bool), |
| 623 | void *arg) |
| 624 | { |
| 625 | struct fstrans_mount_info *fmi; |
| 626 | struct fscow_handler *hp = NULL; |
| 627 | |
| 628 | if ((mp->mnt_iflag & IMNT_HAS_TRANS) == 0) |
| 629 | return EINVAL; |
| 630 | |
| 631 | fmi = mp->mnt_transinfo; |
| 632 | KASSERT(fmi != NULL); |
| 633 | |
| 634 | cow_change_enter(mp); |
| 635 | LIST_FOREACH(hp, &fmi->fmi_cow_handler, ch_list) |
| 636 | if (hp->ch_func == func && hp->ch_arg == arg) |
| 637 | break; |
| 638 | if (hp != NULL) { |
| 639 | LIST_REMOVE(hp, ch_list); |
| 640 | kmem_free(hp, sizeof(*hp)); |
| 641 | } |
| 642 | cow_change_done(mp); |
| 643 | |
| 644 | return hp ? 0 : EINVAL; |
| 645 | } |
| 646 | |
| 647 | /* |
| 648 | * Check for need to copy block that is about to be written. |
| 649 | */ |
| 650 | int |
| 651 | fscow_run(struct buf *bp, bool data_valid) |
| 652 | { |
| 653 | int error, s; |
| 654 | struct mount *mp; |
| 655 | struct fstrans_lwp_info *fli; |
| 656 | struct fstrans_mount_info *fmi; |
| 657 | struct fscow_handler *hp; |
| 658 | |
| 659 | /* |
| 660 | * First check if we need run the copy-on-write handler. |
| 661 | */ |
| 662 | if ((bp->b_flags & B_COWDONE)) |
| 663 | return 0; |
| 664 | if (bp->b_vp == NULL) { |
| 665 | bp->b_flags |= B_COWDONE; |
| 666 | return 0; |
| 667 | } |
| 668 | if (bp->b_vp->v_type == VBLK) |
| 669 | mp = spec_node_getmountedfs(bp->b_vp); |
| 670 | else |
| 671 | mp = bp->b_vp->v_mount; |
| 672 | if (mp == NULL || (mp->mnt_iflag & IMNT_HAS_TRANS) == 0) { |
| 673 | bp->b_flags |= B_COWDONE; |
| 674 | return 0; |
| 675 | } |
| 676 | |
| 677 | fli = fstrans_get_lwp_info(mp, true); |
| 678 | fmi = mp->mnt_transinfo; |
| 679 | |
| 680 | /* |
| 681 | * On non-recursed run check if other threads |
| 682 | * want to change the list. |
| 683 | */ |
| 684 | if (fli->fli_cow_cnt == 0) { |
| 685 | s = pserialize_read_enter(); |
| 686 | if (__predict_false(fmi->fmi_cow_change)) { |
| 687 | pserialize_read_exit(s); |
| 688 | mutex_enter(&fstrans_lock); |
| 689 | while (fmi->fmi_cow_change) |
| 690 | cv_wait(&fstrans_state_cv, &fstrans_lock); |
| 691 | fli->fli_cow_cnt = 1; |
| 692 | mutex_exit(&fstrans_lock); |
| 693 | } else { |
| 694 | fli->fli_cow_cnt = 1; |
| 695 | pserialize_read_exit(s); |
| 696 | } |
| 697 | } else |
| 698 | fli->fli_cow_cnt += 1; |
| 699 | |
| 700 | /* |
| 701 | * Run all copy-on-write handlers, stop on error. |
| 702 | */ |
| 703 | error = 0; |
| 704 | LIST_FOREACH(hp, &fmi->fmi_cow_handler, ch_list) |
| 705 | if ((error = (*hp->ch_func)(hp->ch_arg, bp, data_valid)) != 0) |
| 706 | break; |
| 707 | if (error == 0) |
| 708 | bp->b_flags |= B_COWDONE; |
| 709 | |
| 710 | /* |
| 711 | * Check if other threads want to change the list. |
| 712 | */ |
| 713 | if (fli->fli_cow_cnt > 1) { |
| 714 | fli->fli_cow_cnt -= 1; |
| 715 | } else { |
| 716 | s = pserialize_read_enter(); |
| 717 | if (__predict_false(fmi->fmi_cow_change)) { |
| 718 | pserialize_read_exit(s); |
| 719 | mutex_enter(&fstrans_lock); |
| 720 | fli->fli_cow_cnt = 0; |
| 721 | cv_signal(&fstrans_count_cv); |
| 722 | mutex_exit(&fstrans_lock); |
| 723 | } else { |
| 724 | fli->fli_cow_cnt = 0; |
| 725 | pserialize_read_exit(s); |
| 726 | } |
| 727 | } |
| 728 | |
| 729 | return error; |
| 730 | } |
| 731 | |
| 732 | #if defined(DDB) |
| 733 | void fstrans_dump(int); |
| 734 | |
| 735 | static void |
| 736 | fstrans_print_lwp(struct proc *p, struct lwp *l, int verbose) |
| 737 | { |
| 738 | char prefix[9]; |
| 739 | struct fstrans_lwp_info *fli; |
| 740 | |
| 741 | snprintf(prefix, sizeof(prefix), "%d.%d" , p->p_pid, l->l_lid); |
| 742 | LIST_FOREACH(fli, &fstrans_fli_head, fli_list) { |
| 743 | if (fli->fli_self != l) |
| 744 | continue; |
| 745 | if (fli->fli_trans_cnt == 0 && fli->fli_cow_cnt == 0) { |
| 746 | if (! verbose) |
| 747 | continue; |
| 748 | } |
| 749 | printf("%-8s" , prefix); |
| 750 | if (verbose) |
| 751 | printf(" @%p" , fli); |
| 752 | if (fli->fli_mount != NULL) |
| 753 | printf(" (%s)" , fli->fli_mount->mnt_stat.f_mntonname); |
| 754 | else |
| 755 | printf(" NULL" ); |
| 756 | if (fli->fli_trans_cnt == 0) { |
| 757 | printf(" -" ); |
| 758 | } else { |
| 759 | switch (fli->fli_lock_type) { |
| 760 | case FSTRANS_LAZY: |
| 761 | printf(" lazy" ); |
| 762 | break; |
| 763 | case FSTRANS_SHARED: |
| 764 | printf(" shared" ); |
| 765 | break; |
| 766 | case FSTRANS_EXCL: |
| 767 | printf(" excl" ); |
| 768 | break; |
| 769 | default: |
| 770 | printf(" %#x" , fli->fli_lock_type); |
| 771 | break; |
| 772 | } |
| 773 | } |
| 774 | printf(" %d cow %d\n" , fli->fli_trans_cnt, fli->fli_cow_cnt); |
| 775 | prefix[0] = '\0'; |
| 776 | } |
| 777 | } |
| 778 | |
| 779 | static void |
| 780 | fstrans_print_mount(struct mount *mp, int verbose) |
| 781 | { |
| 782 | struct fstrans_mount_info *fmi; |
| 783 | |
| 784 | fmi = mp->mnt_transinfo; |
| 785 | if (!verbose && (fmi == NULL || fmi->fmi_state == FSTRANS_NORMAL)) |
| 786 | return; |
| 787 | |
| 788 | printf("%-16s " , mp->mnt_stat.f_mntonname); |
| 789 | if (fmi == NULL) { |
| 790 | printf("(null)\n" ); |
| 791 | return; |
| 792 | } |
| 793 | switch (fmi->fmi_state) { |
| 794 | case FSTRANS_NORMAL: |
| 795 | printf("state normal\n" ); |
| 796 | break; |
| 797 | case FSTRANS_SUSPENDING: |
| 798 | printf("state suspending\n" ); |
| 799 | break; |
| 800 | case FSTRANS_SUSPENDED: |
| 801 | printf("state suspended\n" ); |
| 802 | break; |
| 803 | default: |
| 804 | printf("state %#x\n" , fmi->fmi_state); |
| 805 | break; |
| 806 | } |
| 807 | } |
| 808 | |
| 809 | void |
| 810 | fstrans_dump(int full) |
| 811 | { |
| 812 | const struct proclist_desc *pd; |
| 813 | struct proc *p; |
| 814 | struct lwp *l; |
| 815 | struct mount *mp; |
| 816 | |
| 817 | printf("Fstrans locks by lwp:\n" ); |
| 818 | for (pd = proclists; pd->pd_list != NULL; pd++) |
| 819 | PROCLIST_FOREACH(p, pd->pd_list) |
| 820 | LIST_FOREACH(l, &p->p_lwps, l_sibling) |
| 821 | fstrans_print_lwp(p, l, full == 1); |
| 822 | |
| 823 | printf("Fstrans state by mount:\n" ); |
| 824 | TAILQ_FOREACH(mp, &mountlist, mnt_list) |
| 825 | fstrans_print_mount(mp, full == 1); |
| 826 | } |
| 827 | #endif /* defined(DDB) */ |
| 828 | |