1 /* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 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 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)vfs_subr.c 8.31 (Berkeley) 5/26/95 35 * $FreeBSD: src/sys/kern/vfs_subr.c,v 1.249.2.30 2003/04/04 20:35:57 tegge Exp $ 36 */ 37 38 /* 39 * External virtual filesystem routines 40 */ 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/buf.h> 45 #include <sys/conf.h> 46 #include <sys/dirent.h> 47 #include <sys/domain.h> 48 #include <sys/eventhandler.h> 49 #include <sys/fcntl.h> 50 #include <sys/kernel.h> 51 #include <sys/kthread.h> 52 #include <sys/malloc.h> 53 #include <sys/mbuf.h> 54 #include <sys/mount.h> 55 #include <sys/proc.h> 56 #include <sys/reboot.h> 57 #include <sys/socket.h> 58 #include <sys/stat.h> 59 #include <sys/sysctl.h> 60 #include <sys/syslog.h> 61 #include <sys/vmmeter.h> 62 #include <sys/vnode.h> 63 64 #include <machine/limits.h> 65 66 #include <vm/vm.h> 67 #include <vm/vm_object.h> 68 #include <vm/vm_extern.h> 69 #include <vm/vm_kern.h> 70 #include <vm/pmap.h> 71 #include <vm/vm_map.h> 72 #include <vm/vm_page.h> 73 #include <vm/vm_pager.h> 74 #include <vm/vnode_pager.h> 75 76 #include <sys/buf2.h> 77 78 /* 79 * The workitem queue. 80 */ 81 #define SYNCER_MAXDELAY 32 82 static int sysctl_kern_syncdelay(SYSCTL_HANDLER_ARGS); 83 time_t syncdelay = 30; /* max time to delay syncing data */ 84 SYSCTL_PROC(_kern, OID_AUTO, syncdelay, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 85 sysctl_kern_syncdelay, "I", "VFS data synchronization delay"); 86 time_t filedelay = 30; /* time to delay syncing files */ 87 SYSCTL_INT(_kern, OID_AUTO, filedelay, CTLFLAG_RW, 88 &filedelay, 0, "File synchronization delay"); 89 time_t dirdelay = 29; /* time to delay syncing directories */ 90 SYSCTL_INT(_kern, OID_AUTO, dirdelay, CTLFLAG_RW, 91 &dirdelay, 0, "Directory synchronization delay"); 92 time_t metadelay = 28; /* time to delay syncing metadata */ 93 SYSCTL_INT(_kern, OID_AUTO, metadelay, CTLFLAG_RW, 94 &metadelay, 0, "VFS metadata synchronization delay"); 95 time_t retrydelay = 1; /* retry delay after failure */ 96 SYSCTL_INT(_kern, OID_AUTO, retrydelay, CTLFLAG_RW, 97 &retrydelay, 0, "VFS retry synchronization delay"); 98 static int rushjob; /* number of slots to run ASAP */ 99 static int stat_rush_requests; /* number of times I/O speeded up */ 100 SYSCTL_INT(_debug, OID_AUTO, rush_requests, CTLFLAG_RW, 101 &stat_rush_requests, 0, ""); 102 103 LIST_HEAD(synclist, vnode); 104 105 #define SC_FLAG_EXIT (0x1) /* request syncer exit */ 106 #define SC_FLAG_DONE (0x2) /* syncer confirm exit */ 107 108 struct syncer_ctx { 109 struct mount *sc_mp; 110 struct lwkt_token sc_token; 111 struct thread *sc_thread; 112 int sc_flags; 113 struct synclist *syncer_workitem_pending; 114 long syncer_mask; 115 int syncer_delayno; 116 int syncer_forced; 117 int syncer_rushjob; /* sequence vnodes faster */ 118 int syncer_trigger; /* trigger full sync */ 119 long syncer_count; 120 }; 121 122 static void syncer_thread(void *); 123 124 static int 125 sysctl_kern_syncdelay(SYSCTL_HANDLER_ARGS) 126 { 127 int error; 128 int v = syncdelay; 129 130 error = sysctl_handle_int(oidp, &v, 0, req); 131 if (error || !req->newptr) 132 return (error); 133 if (v < 1) 134 v = 1; 135 if (v > SYNCER_MAXDELAY) 136 v = SYNCER_MAXDELAY; 137 syncdelay = v; 138 139 return(0); 140 } 141 142 /* 143 * The workitem queue. 144 * 145 * It is useful to delay writes of file data and filesystem metadata 146 * for tens of seconds so that quickly created and deleted files need 147 * not waste disk bandwidth being created and removed. To realize this, 148 * we append vnodes to a "workitem" queue. When running with a soft 149 * updates implementation, most pending metadata dependencies should 150 * not wait for more than a few seconds. Thus, mounted on block devices 151 * are delayed only about a half the time that file data is delayed. 152 * Similarly, directory updates are more critical, so are only delayed 153 * about a third the time that file data is delayed. Thus, there are 154 * SYNCER_MAXDELAY queues that are processed round-robin at a rate of 155 * one each second (driven off the filesystem syncer process). The 156 * syncer_delayno variable indicates the next queue that is to be processed. 157 * Items that need to be processed soon are placed in this queue: 158 * 159 * syncer_workitem_pending[syncer_delayno] 160 * 161 * A delay of fifteen seconds is done by placing the request fifteen 162 * entries later in the queue: 163 * 164 * syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask] 165 * 166 */ 167 168 /* 169 * Return the number of vnodes on the syncer's timed list. This will 170 * include the syncer vnode (mp->mnt_syncer) so if used, a minimum 171 * value of 1 will be returned. 172 */ 173 long 174 vn_syncer_count(struct mount *mp) 175 { 176 struct syncer_ctx *ctx; 177 178 ctx = mp->mnt_syncer_ctx; 179 if (ctx) 180 return (ctx->syncer_count); 181 return 0; 182 } 183 184 /* 185 * Add an item to the syncer work queue. 186 * 187 * WARNING: Cannot get vp->v_token here if not already held, we must 188 * depend on the syncer_token (which might already be held by 189 * the caller) to protect v_synclist and VONWORKLST. 190 * 191 * WARNING: The syncer depends on this function not blocking if the caller 192 * already holds the syncer token. 193 */ 194 void 195 vn_syncer_add(struct vnode *vp, int delay) 196 { 197 struct syncer_ctx *ctx; 198 int slot; 199 200 ctx = vp->v_mount->mnt_syncer_ctx; 201 lwkt_gettoken(&ctx->sc_token); 202 203 if (vp->v_flag & VONWORKLST) { 204 LIST_REMOVE(vp, v_synclist); 205 --ctx->syncer_count; 206 } 207 if (delay <= 0) { 208 slot = -delay & ctx->syncer_mask; 209 } else { 210 if (delay > SYNCER_MAXDELAY - 2) 211 delay = SYNCER_MAXDELAY - 2; 212 slot = (ctx->syncer_delayno + delay) & ctx->syncer_mask; 213 } 214 215 LIST_INSERT_HEAD(&ctx->syncer_workitem_pending[slot], vp, v_synclist); 216 vsetflags(vp, VONWORKLST); 217 ++ctx->syncer_count; 218 219 lwkt_reltoken(&ctx->sc_token); 220 } 221 222 /* 223 * Removes the vnode from the syncer list. Since we might block while 224 * acquiring the syncer_token we have to [re]check conditions to determine 225 * that it is ok to remove the vnode. 226 * 227 * Force removal if force != 0. This can only occur during a forced unmount. 228 * 229 * vp->v_token held on call 230 */ 231 void 232 vn_syncer_remove(struct vnode *vp, int force) 233 { 234 struct syncer_ctx *ctx; 235 236 ctx = vp->v_mount->mnt_syncer_ctx; 237 lwkt_gettoken(&ctx->sc_token); 238 239 if ((vp->v_flag & (VISDIRTY | VONWORKLST | VOBJDIRTY)) == VONWORKLST && 240 RB_EMPTY(&vp->v_rbdirty_tree)) { 241 vclrflags(vp, VONWORKLST); 242 LIST_REMOVE(vp, v_synclist); 243 --ctx->syncer_count; 244 } else if (force && (vp->v_flag & VONWORKLST)) { 245 vclrflags(vp, VONWORKLST); 246 LIST_REMOVE(vp, v_synclist); 247 --ctx->syncer_count; 248 } 249 250 lwkt_reltoken(&ctx->sc_token); 251 } 252 253 /* 254 * vnode must be locked 255 */ 256 void 257 vclrisdirty(struct vnode *vp) 258 { 259 vclrflags(vp, VISDIRTY); 260 if (vp->v_flag & VONWORKLST) 261 vn_syncer_remove(vp, 0); 262 } 263 264 void 265 vclrobjdirty(struct vnode *vp) 266 { 267 vclrflags(vp, VOBJDIRTY); 268 if (vp->v_flag & VONWORKLST) 269 vn_syncer_remove(vp, 0); 270 } 271 272 /* 273 * vnode must be stable 274 */ 275 void 276 vsetisdirty(struct vnode *vp) 277 { 278 struct syncer_ctx *ctx; 279 280 if ((vp->v_flag & VISDIRTY) == 0) { 281 ctx = vp->v_mount->mnt_syncer_ctx; 282 vsetflags(vp, VISDIRTY); 283 lwkt_gettoken(&ctx->sc_token); 284 if ((vp->v_flag & VONWORKLST) == 0) 285 vn_syncer_add(vp, syncdelay); 286 lwkt_reltoken(&ctx->sc_token); 287 } 288 } 289 290 void 291 vsetobjdirty(struct vnode *vp) 292 { 293 struct syncer_ctx *ctx; 294 295 if ((vp->v_flag & VOBJDIRTY) == 0) { 296 ctx = vp->v_mount->mnt_syncer_ctx; 297 vsetflags(vp, VOBJDIRTY); 298 lwkt_gettoken(&ctx->sc_token); 299 if ((vp->v_flag & VONWORKLST) == 0) 300 vn_syncer_add(vp, syncdelay); 301 lwkt_reltoken(&ctx->sc_token); 302 } 303 } 304 305 /* 306 * Create per-filesystem syncer process 307 */ 308 void 309 vn_syncer_thr_create(struct mount *mp) 310 { 311 struct syncer_ctx *ctx; 312 static int syncalloc = 0; 313 314 ctx = kmalloc(sizeof(struct syncer_ctx), M_TEMP, M_WAITOK | M_ZERO); 315 ctx->sc_mp = mp; 316 ctx->sc_flags = 0; 317 ctx->syncer_workitem_pending = hashinit(SYNCER_MAXDELAY, M_DEVBUF, 318 &ctx->syncer_mask); 319 ctx->syncer_delayno = 0; 320 lwkt_token_init(&ctx->sc_token, "syncer"); 321 mp->mnt_syncer_ctx = ctx; 322 kthread_create(syncer_thread, ctx, &ctx->sc_thread, 323 "syncer%d", ++syncalloc & 0x7FFFFFFF); 324 } 325 326 /* 327 * Stop per-filesystem syncer process 328 */ 329 void 330 vn_syncer_thr_stop(struct mount *mp) 331 { 332 struct syncer_ctx *ctx; 333 334 ctx = mp->mnt_syncer_ctx; 335 if (ctx == NULL) 336 return; 337 338 lwkt_gettoken(&ctx->sc_token); 339 340 /* Signal the syncer process to exit */ 341 ctx->sc_flags |= SC_FLAG_EXIT; 342 wakeup(ctx); 343 344 /* Wait till syncer process exits */ 345 while ((ctx->sc_flags & SC_FLAG_DONE) == 0) { 346 tsleep_interlock(&ctx->sc_flags, 0); 347 lwkt_reltoken(&ctx->sc_token); 348 tsleep(&ctx->sc_flags, PINTERLOCKED, "syncexit", hz); 349 lwkt_gettoken(&ctx->sc_token); 350 } 351 352 mp->mnt_syncer_ctx = NULL; 353 lwkt_reltoken(&ctx->sc_token); 354 355 hashdestroy(ctx->syncer_workitem_pending, M_DEVBUF, ctx->syncer_mask); 356 kfree(ctx, M_TEMP); 357 } 358 359 struct thread *updatethread; 360 361 /* 362 * System filesystem synchronizer daemon. 363 */ 364 static void 365 syncer_thread(void *_ctx) 366 { 367 struct syncer_ctx *ctx = _ctx; 368 struct synclist *slp; 369 struct vnode *vp; 370 long starttime; 371 int *sc_flagsp; 372 int sc_flags; 373 int vnodes_synced = 0; 374 int delta; 375 int dummy = 0; 376 377 for (;;) { 378 kproc_suspend_loop(); 379 380 starttime = time_uptime; 381 lwkt_gettoken(&ctx->sc_token); 382 383 /* 384 * Push files whose dirty time has expired. Be careful 385 * of interrupt race on slp queue. 386 * 387 * Note that vsyncscan() and vn_syncer_one() can pull items 388 * off the same list, so we shift vp's position in the 389 * list immediately. 390 */ 391 slp = &ctx->syncer_workitem_pending[ctx->syncer_delayno]; 392 393 /* 394 * If syncer_trigger is set (from trigger_syncer(mp)), 395 * Immediately do a full filesystem sync and set up the 396 * following full filesystem sync to occur in 1 second. 397 */ 398 if (ctx->syncer_trigger) { 399 ctx->syncer_trigger = 0; 400 if (ctx->sc_mp && ctx->sc_mp->mnt_syncer) { 401 vp = ctx->sc_mp->mnt_syncer; 402 if (vp->v_flag & VONWORKLST) { 403 vn_syncer_add(vp, retrydelay); 404 if (vget(vp, LK_EXCLUSIVE) == 0) { 405 VOP_FSYNC(vp, MNT_LAZY, 0); 406 vput(vp); 407 vnodes_synced++; 408 } 409 } 410 } 411 } 412 413 /* 414 * FSYNC items in this bucket 415 */ 416 while ((vp = LIST_FIRST(slp)) != NULL) { 417 vn_syncer_add(vp, retrydelay); 418 if (ctx->syncer_forced) { 419 if (vget(vp, LK_EXCLUSIVE) == 0) { 420 VOP_FSYNC(vp, MNT_NOWAIT, 0); 421 vput(vp); 422 vnodes_synced++; 423 } 424 } else { 425 if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 426 VOP_FSYNC(vp, MNT_LAZY, 0); 427 vput(vp); 428 vnodes_synced++; 429 } 430 } 431 } 432 433 /* 434 * Increment the slot upon completion. This is typically 435 * one-second but may be faster if the syncer is triggered. 436 */ 437 ctx->syncer_delayno = (ctx->syncer_delayno + 1) & 438 ctx->syncer_mask; 439 440 sc_flags = ctx->sc_flags; 441 442 /* Exit on unmount */ 443 if (sc_flags & SC_FLAG_EXIT) 444 break; 445 446 lwkt_reltoken(&ctx->sc_token); 447 448 /* 449 * Do sync processing for each mount. 450 */ 451 if (ctx->sc_mp) 452 bio_ops_sync(ctx->sc_mp); 453 454 /* 455 * The variable rushjob allows the kernel to speed up the 456 * processing of the filesystem syncer process. A rushjob 457 * value of N tells the filesystem syncer to process the next 458 * N seconds worth of work on its queue ASAP. Currently rushjob 459 * is used by the soft update code to speed up the filesystem 460 * syncer process when the incore state is getting so far 461 * ahead of the disk that the kernel memory pool is being 462 * threatened with exhaustion. 463 */ 464 delta = rushjob - ctx->syncer_rushjob; 465 if ((u_int)delta > syncdelay / 2) { 466 ctx->syncer_rushjob = rushjob - syncdelay / 2; 467 tsleep(&dummy, 0, "rush", 1); 468 continue; 469 } 470 if (delta) { 471 ++ctx->syncer_rushjob; 472 tsleep(&dummy, 0, "rush", 1); 473 continue; 474 } 475 476 /* 477 * Normal syncer operation iterates once a second, unless 478 * specifically triggered. 479 */ 480 if (time_uptime == starttime && 481 ctx->syncer_trigger == 0) { 482 tsleep_interlock(ctx, 0); 483 if (time_uptime == starttime && 484 ctx->syncer_trigger == 0 && 485 (ctx->sc_flags & SC_FLAG_EXIT) == 0) { 486 tsleep(ctx, PINTERLOCKED, "syncer", hz); 487 } 488 } 489 } 490 491 /* 492 * Unmount/exit path for per-filesystem syncers; sc_token held 493 */ 494 ctx->sc_flags |= SC_FLAG_DONE; 495 sc_flagsp = &ctx->sc_flags; 496 lwkt_reltoken(&ctx->sc_token); 497 wakeup(sc_flagsp); 498 499 kthread_exit(); 500 } 501 502 /* 503 * This allows a filesystem to pro-actively request that a dirty 504 * vnode be fsync()d. This routine does not guarantee that one 505 * will actually be fsynced. 506 */ 507 void 508 vn_syncer_one(struct mount *mp) 509 { 510 struct syncer_ctx *ctx; 511 struct synclist *slp; 512 struct vnode *vp; 513 int i; 514 int n = syncdelay; 515 516 ctx = mp->mnt_syncer_ctx; 517 i = ctx->syncer_delayno & ctx->syncer_mask; 518 cpu_ccfence(); 519 520 if (lwkt_trytoken(&ctx->sc_token) == 0) 521 return; 522 523 /* 524 * Look ahead on our syncer time array. 525 */ 526 do { 527 slp = &ctx->syncer_workitem_pending[i]; 528 vp = LIST_FIRST(slp); 529 if (vp && vp->v_type == VNON) 530 vp = LIST_NEXT(vp, v_synclist); 531 if (vp) 532 break; 533 i = (i + 1) & ctx->syncer_mask; 534 /* i will be wrong if we stop here but vp is NULL so ok */ 535 } while(--n); 536 537 /* 538 * Process one vnode, skip the syncer vnode but also stop 539 * if the syncer vnode is the only thing on this list. 540 */ 541 if (vp) { 542 vn_syncer_add(vp, retrydelay); 543 if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 544 VOP_FSYNC(vp, MNT_LAZY, 0); 545 vput(vp); 546 } 547 } 548 lwkt_reltoken(&ctx->sc_token); 549 } 550 551 /* 552 * Request that the syncer daemon for a specific mount speed up its work. 553 * If mp is NULL the caller generally wants to speed up all syncers. 554 */ 555 void 556 speedup_syncer(struct mount *mp) 557 { 558 /* 559 * Don't bother protecting the test. unsleep_and_wakeup_thread() 560 * will only do something real if the thread is in the right state. 561 */ 562 atomic_add_int(&rushjob, 1); 563 ++stat_rush_requests; 564 if (mp && mp->mnt_syncer_ctx) 565 wakeup(mp->mnt_syncer_ctx); 566 } 567 568 /* 569 * trigger a full sync 570 */ 571 void 572 trigger_syncer(struct mount *mp) 573 { 574 struct syncer_ctx *ctx; 575 576 if (mp && (ctx = mp->mnt_syncer_ctx) != NULL) { 577 if (ctx->syncer_trigger == 0) { 578 ctx->syncer_trigger = 1; 579 wakeup(ctx); 580 } 581 } 582 } 583 584 /* 585 * Routine to create and manage a filesystem syncer vnode. 586 */ 587 static int sync_close(struct vop_close_args *); 588 static int sync_fsync(struct vop_fsync_args *); 589 static int sync_inactive(struct vop_inactive_args *); 590 static int sync_reclaim (struct vop_reclaim_args *); 591 static int sync_print(struct vop_print_args *); 592 593 static struct vop_ops sync_vnode_vops = { 594 .vop_default = vop_eopnotsupp, 595 .vop_close = sync_close, 596 .vop_fsync = sync_fsync, 597 .vop_inactive = sync_inactive, 598 .vop_reclaim = sync_reclaim, 599 .vop_print = sync_print, 600 }; 601 602 static struct vop_ops *sync_vnode_vops_p = &sync_vnode_vops; 603 604 VNODEOP_SET(sync_vnode_vops); 605 606 /* 607 * Create a new filesystem syncer vnode for the specified mount point. 608 * This vnode is placed on the worklist and is responsible for sync'ing 609 * the filesystem. 610 * 611 * NOTE: read-only mounts are also placed on the worklist. The filesystem 612 * sync code is also responsible for cleaning up vnodes. 613 */ 614 int 615 vfs_allocate_syncvnode(struct mount *mp) 616 { 617 struct vnode *vp; 618 static long start, incr, next; 619 int error; 620 621 /* Allocate a new vnode */ 622 error = getspecialvnode(VT_VFS, mp, &sync_vnode_vops_p, &vp, 0, 0); 623 if (error) { 624 mp->mnt_syncer = NULL; 625 return (error); 626 } 627 vp->v_type = VNON; 628 /* 629 * Place the vnode onto the syncer worklist. We attempt to 630 * scatter them about on the list so that they will go off 631 * at evenly distributed times even if all the filesystems 632 * are mounted at once. 633 */ 634 next += incr; 635 if (next == 0 || next > SYNCER_MAXDELAY) { 636 start /= 2; 637 incr /= 2; 638 if (start == 0) { 639 start = SYNCER_MAXDELAY / 2; 640 incr = SYNCER_MAXDELAY; 641 } 642 next = start; 643 } 644 645 /* 646 * Only put the syncer vnode onto the syncer list if we have a 647 * syncer thread. Some VFS's (aka NULLFS) don't need a syncer 648 * thread. 649 */ 650 if (mp->mnt_syncer_ctx) 651 vn_syncer_add(vp, syncdelay > 0 ? next % syncdelay : 0); 652 653 /* 654 * The mnt_syncer field inherits the vnode reference, which is 655 * held until later decomissioning. 656 */ 657 mp->mnt_syncer = vp; 658 vx_unlock(vp); 659 return (0); 660 } 661 662 static int 663 sync_close(struct vop_close_args *ap) 664 { 665 return (0); 666 } 667 668 /* 669 * Do a lazy sync of the filesystem. 670 * 671 * sync_fsync { struct vnode *a_vp, int a_waitfor } 672 */ 673 static int 674 sync_fsync(struct vop_fsync_args *ap) 675 { 676 struct vnode *syncvp = ap->a_vp; 677 struct mount *mp = syncvp->v_mount; 678 int asyncflag; 679 680 /* 681 * We only need to do something if this is a lazy evaluation. 682 */ 683 if ((ap->a_waitfor & MNT_LAZY) == 0) 684 return (0); 685 686 /* 687 * Move ourselves to the back of the sync list. 688 */ 689 vn_syncer_add(syncvp, syncdelay); 690 691 /* 692 * Walk the list of vnodes pushing all that are dirty and 693 * not already on the sync list, and freeing vnodes which have 694 * no refs and whos VM objects are empty. vfs_msync() handles 695 * the VM issues and must be called whether the mount is readonly 696 * or not. 697 */ 698 if (vfs_busy(mp, LK_NOWAIT) != 0) 699 return (0); 700 if (mp->mnt_flag & MNT_RDONLY) { 701 vfs_msync(mp, MNT_NOWAIT); 702 } else { 703 asyncflag = mp->mnt_flag & MNT_ASYNC; 704 mp->mnt_flag &= ~MNT_ASYNC; /* ZZZ hack */ 705 vfs_msync(mp, MNT_NOWAIT); 706 VFS_SYNC(mp, MNT_NOWAIT | MNT_LAZY); 707 if (asyncflag) 708 mp->mnt_flag |= MNT_ASYNC; 709 } 710 vfs_unbusy(mp); 711 return (0); 712 } 713 714 /* 715 * The syncer vnode is no longer referenced. 716 * 717 * sync_inactive { struct vnode *a_vp, struct proc *a_p } 718 */ 719 static int 720 sync_inactive(struct vop_inactive_args *ap) 721 { 722 vgone_vxlocked(ap->a_vp); 723 return (0); 724 } 725 726 /* 727 * The syncer vnode is no longer needed and is being decommissioned. 728 * This can only occur when the last reference has been released on 729 * mp->mnt_syncer, so mp->mnt_syncer had better be NULL. 730 * 731 * Modifications to the worklist must be protected with a critical 732 * section. 733 * 734 * sync_reclaim { struct vnode *a_vp } 735 */ 736 static int 737 sync_reclaim(struct vop_reclaim_args *ap) 738 { 739 struct vnode *vp = ap->a_vp; 740 struct syncer_ctx *ctx; 741 742 ctx = vp->v_mount->mnt_syncer_ctx; 743 if (ctx) { 744 lwkt_gettoken(&ctx->sc_token); 745 KKASSERT(vp->v_mount->mnt_syncer != vp); 746 if (vp->v_flag & VONWORKLST) { 747 LIST_REMOVE(vp, v_synclist); 748 vclrflags(vp, VONWORKLST); 749 --ctx->syncer_count; 750 } 751 lwkt_reltoken(&ctx->sc_token); 752 } else { 753 KKASSERT((vp->v_flag & VONWORKLST) == 0); 754 } 755 756 return (0); 757 } 758 759 /* 760 * This is very similar to vmntvnodescan() but it only scans the 761 * vnodes on the syncer list. VFS's which support faster VFS_SYNC 762 * operations use the VISDIRTY flag on the vnode to ensure that vnodes 763 * with dirty inodes are added to the syncer in addition to vnodes 764 * with dirty buffers, and can use this function instead of nmntvnodescan(). 765 * 766 * This scan does not issue VOP_FSYNC()s. The supplied callback is intended 767 * to synchronize the file in the manner intended by the VFS using it. 768 * 769 * This is important when a system has millions of vnodes. 770 */ 771 int 772 vsyncscan( 773 struct mount *mp, 774 int vmsc_flags, 775 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data), 776 void *data 777 ) { 778 struct syncer_ctx *ctx; 779 struct synclist *slp; 780 struct vnode *vp; 781 int i; 782 int count; 783 int lkflags; 784 785 if (vmsc_flags & VMSC_NOWAIT) 786 lkflags = LK_NOWAIT; 787 else 788 lkflags = 0; 789 790 /* 791 * Syncer list context. This API requires a dedicated syncer thread. 792 * (MNTK_THR_SYNC). 793 */ 794 KKASSERT(mp->mnt_kern_flag & MNTK_THR_SYNC); 795 ctx = mp->mnt_syncer_ctx; 796 lwkt_gettoken(&ctx->sc_token); 797 798 /* 799 * Setup for loop. Allow races against the syncer thread but 800 * require that the syncer thread no be lazy if we were told 801 * not to be lazy. 802 */ 803 i = ctx->syncer_delayno & ctx->syncer_mask; 804 if ((vmsc_flags & VMSC_NOWAIT) == 0) 805 ++ctx->syncer_forced; 806 for (count = 0; count <= ctx->syncer_mask; ++count) { 807 slp = &ctx->syncer_workitem_pending[i]; 808 809 while ((vp = LIST_FIRST(slp)) != NULL) { 810 KKASSERT(vp->v_mount == mp); 811 if (vmsc_flags & VMSC_GETVP) { 812 if (vget(vp, LK_EXCLUSIVE | lkflags) == 0) { 813 slowfunc(mp, vp, data); 814 vput(vp); 815 } 816 } else if (vmsc_flags & VMSC_GETVX) { 817 vx_get(vp); 818 slowfunc(mp, vp, data); 819 vx_put(vp); 820 } else { 821 vhold(vp); 822 slowfunc(mp, vp, data); 823 vdrop(vp); 824 } 825 826 /* 827 * vp could be invalid. However, if vp is still at 828 * the head of the list it is clearly valid and we 829 * can safely move it. 830 */ 831 if (LIST_FIRST(slp) == vp) 832 vn_syncer_add(vp, -(i + syncdelay)); 833 } 834 i = (i + 1) & ctx->syncer_mask; 835 } 836 837 if ((vmsc_flags & VMSC_NOWAIT) == 0) 838 --ctx->syncer_forced; 839 lwkt_reltoken(&ctx->sc_token); 840 return(0); 841 } 842 843 /* 844 * Print out a syncer vnode. 845 * 846 * sync_print { struct vnode *a_vp } 847 */ 848 static int 849 sync_print(struct vop_print_args *ap) 850 { 851 struct vnode *vp = ap->a_vp; 852 853 kprintf("syncer vnode"); 854 lockmgr_printinfo(&vp->v_lock); 855 kprintf("\n"); 856 return (0); 857 } 858 859