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/namei.h> 57 #include <sys/reboot.h> 58 #include <sys/socket.h> 59 #include <sys/stat.h> 60 #include <sys/sysctl.h> 61 #include <sys/syslog.h> 62 #include <sys/vmmeter.h> 63 #include <sys/vnode.h> 64 65 #include <machine/limits.h> 66 67 #include <vm/vm.h> 68 #include <vm/vm_object.h> 69 #include <vm/vm_extern.h> 70 #include <vm/vm_kern.h> 71 #include <vm/pmap.h> 72 #include <vm/vm_map.h> 73 #include <vm/vm_page.h> 74 #include <vm/vm_pager.h> 75 #include <vm/vnode_pager.h> 76 77 #include <sys/buf2.h> 78 #include <sys/thread2.h> 79 80 /* 81 * The workitem queue. 82 */ 83 #define SYNCER_MAXDELAY 32 84 static int sysctl_kern_syncdelay(SYSCTL_HANDLER_ARGS); 85 time_t syncdelay = 30; /* max time to delay syncing data */ 86 SYSCTL_PROC(_kern, OID_AUTO, syncdelay, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 87 sysctl_kern_syncdelay, "I", "VFS data synchronization delay"); 88 time_t filedelay = 30; /* time to delay syncing files */ 89 SYSCTL_INT(_kern, OID_AUTO, filedelay, CTLFLAG_RW, 90 &filedelay, 0, "File synchronization delay"); 91 time_t dirdelay = 29; /* time to delay syncing directories */ 92 SYSCTL_INT(_kern, OID_AUTO, dirdelay, CTLFLAG_RW, 93 &dirdelay, 0, "Directory synchronization delay"); 94 time_t metadelay = 28; /* time to delay syncing metadata */ 95 SYSCTL_INT(_kern, OID_AUTO, metadelay, CTLFLAG_RW, 96 &metadelay, 0, "VFS metadata synchronization delay"); 97 static int rushjob; /* number of slots to run ASAP */ 98 static int stat_rush_requests; /* number of times I/O speeded up */ 99 SYSCTL_INT(_debug, OID_AUTO, rush_requests, CTLFLAG_RW, 100 &stat_rush_requests, 0, ""); 101 102 LIST_HEAD(synclist, vnode); 103 104 #define SC_FLAG_EXIT (0x1) /* request syncer exit */ 105 #define SC_FLAG_DONE (0x2) /* syncer confirm exit */ 106 107 struct syncer_ctx { 108 struct mount *sc_mp; 109 struct lwkt_token sc_token; 110 struct thread *sc_thread; 111 int sc_flags; 112 struct synclist *syncer_workitem_pending; 113 long syncer_mask; 114 int syncer_delayno; 115 int syncer_forced; 116 int syncer_rushjob; 117 }; 118 119 static void syncer_thread(void *); 120 121 static int 122 sysctl_kern_syncdelay(SYSCTL_HANDLER_ARGS) 123 { 124 int error; 125 int v = syncdelay; 126 127 error = sysctl_handle_int(oidp, &v, 0, req); 128 if (error || !req->newptr) 129 return (error); 130 if (v < 1) 131 v = 1; 132 if (v > SYNCER_MAXDELAY) 133 v = SYNCER_MAXDELAY; 134 syncdelay = v; 135 136 return(0); 137 } 138 139 /* 140 * The workitem queue. 141 * 142 * It is useful to delay writes of file data and filesystem metadata 143 * for tens of seconds so that quickly created and deleted files need 144 * not waste disk bandwidth being created and removed. To realize this, 145 * we append vnodes to a "workitem" queue. When running with a soft 146 * updates implementation, most pending metadata dependencies should 147 * not wait for more than a few seconds. Thus, mounted on block devices 148 * are delayed only about a half the time that file data is delayed. 149 * Similarly, directory updates are more critical, so are only delayed 150 * about a third the time that file data is delayed. Thus, there are 151 * SYNCER_MAXDELAY queues that are processed round-robin at a rate of 152 * one each second (driven off the filesystem syncer process). The 153 * syncer_delayno variable indicates the next queue that is to be processed. 154 * Items that need to be processed soon are placed in this queue: 155 * 156 * syncer_workitem_pending[syncer_delayno] 157 * 158 * A delay of fifteen seconds is done by placing the request fifteen 159 * entries later in the queue: 160 * 161 * syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask] 162 * 163 */ 164 165 /* 166 * Add an item to the syncer work queue. 167 * 168 * WARNING: Cannot get vp->v_token here if not already held, we must 169 * depend on the syncer_token (which might already be held by 170 * the caller) to protect v_synclist and VONWORKLST. 171 * 172 * MPSAFE 173 */ 174 void 175 vn_syncer_add(struct vnode *vp, int delay) 176 { 177 struct syncer_ctx *ctx; 178 int slot; 179 180 ctx = vp->v_mount->mnt_syncer_ctx; 181 lwkt_gettoken(&ctx->sc_token); 182 183 if (vp->v_flag & VONWORKLST) 184 LIST_REMOVE(vp, v_synclist); 185 if (delay <= 0) { 186 slot = -delay & ctx->syncer_mask; 187 } else { 188 if (delay > SYNCER_MAXDELAY - 2) 189 delay = SYNCER_MAXDELAY - 2; 190 slot = (ctx->syncer_delayno + delay) & ctx->syncer_mask; 191 } 192 193 LIST_INSERT_HEAD(&ctx->syncer_workitem_pending[slot], vp, v_synclist); 194 vsetflags(vp, VONWORKLST); 195 196 lwkt_reltoken(&ctx->sc_token); 197 } 198 199 /* 200 * Removes the vnode from the syncer list. Since we might block while 201 * acquiring the syncer_token we have to recheck conditions. 202 * 203 * vp->v_token held on call 204 */ 205 void 206 vn_syncer_remove(struct vnode *vp) 207 { 208 struct syncer_ctx *ctx; 209 210 ctx = vp->v_mount->mnt_syncer_ctx; 211 lwkt_gettoken(&ctx->sc_token); 212 213 if ((vp->v_flag & (VISDIRTY | VONWORKLST | VOBJDIRTY)) == VONWORKLST && 214 RB_EMPTY(&vp->v_rbdirty_tree)) { 215 vclrflags(vp, VONWORKLST); 216 LIST_REMOVE(vp, v_synclist); 217 } 218 219 lwkt_reltoken(&ctx->sc_token); 220 } 221 222 /* 223 * vnode must be locked 224 */ 225 void 226 vclrisdirty(struct vnode *vp) 227 { 228 vclrflags(vp, VISDIRTY); 229 if (vp->v_flag & VONWORKLST) 230 vn_syncer_remove(vp); 231 } 232 233 void 234 vclrobjdirty(struct vnode *vp) 235 { 236 vclrflags(vp, VOBJDIRTY); 237 if (vp->v_flag & VONWORKLST) 238 vn_syncer_remove(vp); 239 } 240 241 /* 242 * vnode must be stable 243 */ 244 void 245 vsetisdirty(struct vnode *vp) 246 { 247 struct syncer_ctx *ctx; 248 249 if ((vp->v_flag & VISDIRTY) == 0) { 250 ctx = vp->v_mount->mnt_syncer_ctx; 251 vsetflags(vp, VISDIRTY); 252 lwkt_gettoken(&ctx->sc_token); 253 if ((vp->v_flag & VONWORKLST) == 0) 254 vn_syncer_add(vp, syncdelay); 255 lwkt_reltoken(&ctx->sc_token); 256 } 257 } 258 259 void 260 vsetobjdirty(struct vnode *vp) 261 { 262 struct syncer_ctx *ctx; 263 264 if ((vp->v_flag & VOBJDIRTY) == 0) { 265 ctx = vp->v_mount->mnt_syncer_ctx; 266 vsetflags(vp, VOBJDIRTY); 267 lwkt_gettoken(&ctx->sc_token); 268 if ((vp->v_flag & VONWORKLST) == 0) 269 vn_syncer_add(vp, syncdelay); 270 lwkt_reltoken(&ctx->sc_token); 271 } 272 } 273 274 /* 275 * Create per-filesystem syncer process 276 */ 277 void 278 vn_syncer_thr_create(struct mount *mp) 279 { 280 struct syncer_ctx *ctx; 281 static int syncalloc = 0; 282 283 ctx = kmalloc(sizeof(struct syncer_ctx), M_TEMP, M_WAITOK | M_ZERO); 284 ctx->sc_mp = mp; 285 ctx->sc_flags = 0; 286 ctx->syncer_workitem_pending = hashinit(SYNCER_MAXDELAY, M_DEVBUF, 287 &ctx->syncer_mask); 288 ctx->syncer_delayno = 0; 289 lwkt_token_init(&ctx->sc_token, "syncer"); 290 mp->mnt_syncer_ctx = ctx; 291 kthread_create(syncer_thread, ctx, &ctx->sc_thread, 292 "syncer%d", ++syncalloc & 0x7FFFFFFF); 293 } 294 295 /* 296 * Stop per-filesystem syncer process 297 */ 298 void 299 vn_syncer_thr_stop(struct mount *mp) 300 { 301 struct syncer_ctx *ctx; 302 303 ctx = mp->mnt_syncer_ctx; 304 if (ctx == NULL) 305 return; 306 307 lwkt_gettoken(&ctx->sc_token); 308 309 /* Signal the syncer process to exit */ 310 ctx->sc_flags |= SC_FLAG_EXIT; 311 wakeup(ctx); 312 313 /* Wait till syncer process exits */ 314 while ((ctx->sc_flags & SC_FLAG_DONE) == 0) 315 tsleep(&ctx->sc_flags, 0, "syncexit", hz); 316 317 mp->mnt_syncer_ctx = NULL; 318 lwkt_reltoken(&ctx->sc_token); 319 320 hashdestroy(ctx->syncer_workitem_pending, M_DEVBUF, ctx->syncer_mask); 321 kfree(ctx, M_TEMP); 322 } 323 324 struct thread *updatethread; 325 326 /* 327 * System filesystem synchronizer daemon. 328 */ 329 static void 330 syncer_thread(void *_ctx) 331 { 332 struct syncer_ctx *ctx = _ctx; 333 struct synclist *slp; 334 struct vnode *vp; 335 long starttime; 336 int *sc_flagsp; 337 int sc_flags; 338 int vnodes_synced = 0; 339 int delta; 340 int dummy = 0; 341 342 for (;;) { 343 kproc_suspend_loop(); 344 345 starttime = time_uptime; 346 lwkt_gettoken(&ctx->sc_token); 347 348 /* 349 * Push files whose dirty time has expired. Be careful 350 * of interrupt race on slp queue. 351 */ 352 slp = &ctx->syncer_workitem_pending[ctx->syncer_delayno]; 353 ctx->syncer_delayno = (ctx->syncer_delayno + 1) & 354 ctx->syncer_mask; 355 356 while ((vp = LIST_FIRST(slp)) != NULL) { 357 if (ctx->syncer_forced) { 358 if (vget(vp, LK_EXCLUSIVE) == 0) { 359 VOP_FSYNC(vp, MNT_NOWAIT, 0); 360 vput(vp); 361 vnodes_synced++; 362 } 363 } else { 364 if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 365 VOP_FSYNC(vp, MNT_LAZY, 0); 366 vput(vp); 367 vnodes_synced++; 368 } 369 } 370 371 /* 372 * vp is stale but can still be used if we can 373 * verify that it remains at the head of the list. 374 * Be careful not to try to get vp->v_token as 375 * vp can become stale if this blocks. 376 * 377 * If the vp is still at the head of the list were 378 * unable to completely flush it and move it to 379 * a later slot to give other vnodes a fair shot. 380 * 381 * Note that v_tag VT_VFS vnodes can remain on the 382 * worklist with no dirty blocks, but sync_fsync() 383 * moves it to a later slot so we will never see it 384 * here. 385 * 386 * It is possible to race a vnode with no dirty 387 * buffers being removed from the list. If this 388 * occurs we will move the vnode in the synclist 389 * and then the other thread will remove it. Do 390 * not try to remove it here. 391 */ 392 if (LIST_FIRST(slp) == vp) 393 vn_syncer_add(vp, syncdelay); 394 } 395 396 sc_flags = ctx->sc_flags; 397 398 /* Exit on unmount */ 399 if (sc_flags & SC_FLAG_EXIT) 400 break; 401 402 lwkt_reltoken(&ctx->sc_token); 403 404 /* 405 * Do sync processing for each mount. 406 */ 407 if (ctx->sc_mp) 408 bio_ops_sync(ctx->sc_mp); 409 410 /* 411 * The variable rushjob allows the kernel to speed up the 412 * processing of the filesystem syncer process. A rushjob 413 * value of N tells the filesystem syncer to process the next 414 * N seconds worth of work on its queue ASAP. Currently rushjob 415 * is used by the soft update code to speed up the filesystem 416 * syncer process when the incore state is getting so far 417 * ahead of the disk that the kernel memory pool is being 418 * threatened with exhaustion. 419 */ 420 delta = rushjob - ctx->syncer_rushjob; 421 if ((u_int)delta > syncdelay / 2) { 422 ctx->syncer_rushjob = rushjob - syncdelay / 2; 423 tsleep(&dummy, 0, "rush", 1); 424 continue; 425 } 426 if (delta) { 427 ++ctx->syncer_rushjob; 428 tsleep(&dummy, 0, "rush", 1); 429 continue; 430 } 431 432 /* 433 * If it has taken us less than a second to process the 434 * current work, then wait. Otherwise start right over 435 * again. We can still lose time if any single round 436 * takes more than two seconds, but it does not really 437 * matter as we are just trying to generally pace the 438 * filesystem activity. 439 */ 440 if (time_uptime == starttime) 441 tsleep(ctx, 0, "syncer", hz); 442 } 443 444 /* 445 * Unmount/exit path for per-filesystem syncers; sc_token held 446 */ 447 ctx->sc_flags |= SC_FLAG_DONE; 448 sc_flagsp = &ctx->sc_flags; 449 lwkt_reltoken(&ctx->sc_token); 450 wakeup(sc_flagsp); 451 452 kthread_exit(); 453 } 454 455 /* 456 * Request that the syncer daemon for a specific mount speed up its work. 457 * If mp is NULL the caller generally wants to speed up all syncers. 458 */ 459 void 460 speedup_syncer(struct mount *mp) 461 { 462 /* 463 * Don't bother protecting the test. unsleep_and_wakeup_thread() 464 * will only do something real if the thread is in the right state. 465 */ 466 atomic_add_int(&rushjob, 1); 467 ++stat_rush_requests; 468 if (mp) 469 wakeup(mp->mnt_syncer_ctx); 470 } 471 472 /* 473 * Routine to create and manage a filesystem syncer vnode. 474 */ 475 static int sync_close(struct vop_close_args *); 476 static int sync_fsync(struct vop_fsync_args *); 477 static int sync_inactive(struct vop_inactive_args *); 478 static int sync_reclaim (struct vop_reclaim_args *); 479 static int sync_print(struct vop_print_args *); 480 481 static struct vop_ops sync_vnode_vops = { 482 .vop_default = vop_eopnotsupp, 483 .vop_close = sync_close, 484 .vop_fsync = sync_fsync, 485 .vop_inactive = sync_inactive, 486 .vop_reclaim = sync_reclaim, 487 .vop_print = sync_print, 488 }; 489 490 static struct vop_ops *sync_vnode_vops_p = &sync_vnode_vops; 491 492 VNODEOP_SET(sync_vnode_vops); 493 494 /* 495 * Create a new filesystem syncer vnode for the specified mount point. 496 * This vnode is placed on the worklist and is responsible for sync'ing 497 * the filesystem. 498 * 499 * NOTE: read-only mounts are also placed on the worklist. The filesystem 500 * sync code is also responsible for cleaning up vnodes. 501 */ 502 int 503 vfs_allocate_syncvnode(struct mount *mp) 504 { 505 struct vnode *vp; 506 static long start, incr, next; 507 int error; 508 509 /* Allocate a new vnode */ 510 error = getspecialvnode(VT_VFS, mp, &sync_vnode_vops_p, &vp, 0, 0); 511 if (error) { 512 mp->mnt_syncer = NULL; 513 return (error); 514 } 515 vp->v_type = VNON; 516 /* 517 * Place the vnode onto the syncer worklist. We attempt to 518 * scatter them about on the list so that they will go off 519 * at evenly distributed times even if all the filesystems 520 * are mounted at once. 521 */ 522 next += incr; 523 if (next == 0 || next > SYNCER_MAXDELAY) { 524 start /= 2; 525 incr /= 2; 526 if (start == 0) { 527 start = SYNCER_MAXDELAY / 2; 528 incr = SYNCER_MAXDELAY; 529 } 530 next = start; 531 } 532 533 /* 534 * Only put the syncer vnode onto the syncer list if we have a 535 * syncer thread. Some VFS's (aka NULLFS) don't need a syncer 536 * thread. 537 */ 538 if (mp->mnt_syncer_ctx) 539 vn_syncer_add(vp, syncdelay > 0 ? next % syncdelay : 0); 540 541 /* 542 * The mnt_syncer field inherits the vnode reference, which is 543 * held until later decomissioning. 544 */ 545 mp->mnt_syncer = vp; 546 vx_unlock(vp); 547 return (0); 548 } 549 550 static int 551 sync_close(struct vop_close_args *ap) 552 { 553 return (0); 554 } 555 556 /* 557 * Do a lazy sync of the filesystem. 558 * 559 * sync_fsync { struct vnode *a_vp, int a_waitfor } 560 */ 561 static int 562 sync_fsync(struct vop_fsync_args *ap) 563 { 564 struct vnode *syncvp = ap->a_vp; 565 struct mount *mp = syncvp->v_mount; 566 int asyncflag; 567 568 /* 569 * We only need to do something if this is a lazy evaluation. 570 */ 571 if ((ap->a_waitfor & MNT_LAZY) == 0) 572 return (0); 573 574 /* 575 * Move ourselves to the back of the sync list. 576 */ 577 vn_syncer_add(syncvp, syncdelay); 578 579 /* 580 * Walk the list of vnodes pushing all that are dirty and 581 * not already on the sync list, and freeing vnodes which have 582 * no refs and whos VM objects are empty. vfs_msync() handles 583 * the VM issues and must be called whether the mount is readonly 584 * or not. 585 */ 586 if (vfs_busy(mp, LK_NOWAIT) != 0) 587 return (0); 588 if (mp->mnt_flag & MNT_RDONLY) { 589 vfs_msync(mp, MNT_NOWAIT); 590 } else { 591 asyncflag = mp->mnt_flag & MNT_ASYNC; 592 mp->mnt_flag &= ~MNT_ASYNC; /* ZZZ hack */ 593 vfs_msync(mp, MNT_NOWAIT); 594 VFS_SYNC(mp, MNT_NOWAIT | MNT_LAZY); 595 if (asyncflag) 596 mp->mnt_flag |= MNT_ASYNC; 597 } 598 vfs_unbusy(mp); 599 return (0); 600 } 601 602 /* 603 * The syncer vnode is no longer referenced. 604 * 605 * sync_inactive { struct vnode *a_vp, struct proc *a_p } 606 */ 607 static int 608 sync_inactive(struct vop_inactive_args *ap) 609 { 610 vgone_vxlocked(ap->a_vp); 611 return (0); 612 } 613 614 /* 615 * The syncer vnode is no longer needed and is being decommissioned. 616 * This can only occur when the last reference has been released on 617 * mp->mnt_syncer, so mp->mnt_syncer had better be NULL. 618 * 619 * Modifications to the worklist must be protected with a critical 620 * section. 621 * 622 * sync_reclaim { struct vnode *a_vp } 623 */ 624 static int 625 sync_reclaim(struct vop_reclaim_args *ap) 626 { 627 struct vnode *vp = ap->a_vp; 628 struct syncer_ctx *ctx; 629 630 ctx = vp->v_mount->mnt_syncer_ctx; 631 if (ctx) { 632 lwkt_gettoken(&ctx->sc_token); 633 KKASSERT(vp->v_mount->mnt_syncer != vp); 634 if (vp->v_flag & VONWORKLST) { 635 LIST_REMOVE(vp, v_synclist); 636 vclrflags(vp, VONWORKLST); 637 } 638 lwkt_reltoken(&ctx->sc_token); 639 } else { 640 KKASSERT((vp->v_flag & VONWORKLST) == 0); 641 } 642 643 return (0); 644 } 645 646 /* 647 * This is very similar to vmntvnodescan() but it only scans the 648 * vnodes on the syncer list. VFS's which support faster VFS_SYNC 649 * operations use the VISDIRTY flag on the vnode to ensure that vnodes 650 * with dirty inodes are added to the syncer in addition to vnodes 651 * with dirty buffers, and can use this function instead of nmntvnodescan(). 652 * 653 * This is important when a system has millions of vnodes. 654 */ 655 int 656 vsyncscan( 657 struct mount *mp, 658 int vmsc_flags, 659 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data), 660 void *data 661 ) { 662 struct syncer_ctx *ctx; 663 struct synclist *slp; 664 struct vnode *vp; 665 int b; 666 int i; 667 int lkflags; 668 669 if (vmsc_flags & VMSC_NOWAIT) 670 lkflags = LK_NOWAIT; 671 else 672 lkflags = 0; 673 674 /* 675 * Syncer list context. This API requires a dedicated syncer thread. 676 * (MNTK_THR_SYNC). 677 */ 678 KKASSERT(mp->mnt_kern_flag & MNTK_THR_SYNC); 679 ctx = mp->mnt_syncer_ctx; 680 lwkt_gettoken(&ctx->sc_token); 681 682 /* 683 * Setup for loop. Allow races against the syncer thread but 684 * require that the syncer thread no be lazy if we were told 685 * not to be lazy. 686 */ 687 b = ctx->syncer_delayno & ctx->syncer_mask; 688 i = b; 689 if ((vmsc_flags & VMSC_NOWAIT) == 0) 690 ++ctx->syncer_forced; 691 692 do { 693 slp = &ctx->syncer_workitem_pending[i]; 694 695 while ((vp = LIST_FIRST(slp)) != NULL) { 696 KKASSERT(vp->v_mount == mp); 697 if (vmsc_flags & VMSC_GETVP) { 698 if (vget(vp, LK_EXCLUSIVE | lkflags) == 0) { 699 slowfunc(mp, vp, data); 700 vput(vp); 701 } 702 } else if (vmsc_flags & VMSC_GETVX) { 703 vx_get(vp); 704 slowfunc(mp, vp, data); 705 vx_put(vp); 706 } else { 707 vhold(vp); 708 slowfunc(mp, vp, data); 709 vdrop(vp); 710 } 711 if (LIST_FIRST(slp) == vp) 712 vn_syncer_add(vp, -(i + syncdelay)); 713 } 714 i = (i + 1) & ctx->syncer_mask; 715 } while (i != b); 716 717 if ((vmsc_flags & VMSC_NOWAIT) == 0) 718 --ctx->syncer_forced; 719 lwkt_reltoken(&ctx->sc_token); 720 return(0); 721 } 722 723 /* 724 * Print out a syncer vnode. 725 * 726 * sync_print { struct vnode *a_vp } 727 */ 728 static int 729 sync_print(struct vop_print_args *ap) 730 { 731 struct vnode *vp = ap->a_vp; 732 733 kprintf("syncer vnode"); 734 lockmgr_printinfo(&vp->v_lock); 735 kprintf("\n"); 736 return (0); 737 } 738 739