1 /* 2 * Copyright (c) 2004 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * Copyright (c) 1989, 1993 35 * The Regents of the University of California. All rights reserved. 36 * (c) UNIX System Laboratories, Inc. 37 * All or some portions of this file are derived from material licensed 38 * to the University of California by American Telephone and Telegraph 39 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 40 * the permission of UNIX System Laboratories, Inc. 41 * 42 * Redistribution and use in source and binary forms, with or without 43 * modification, are permitted provided that the following conditions 44 * are met: 45 * 1. Redistributions of source code must retain the above copyright 46 * notice, this list of conditions and the following disclaimer. 47 * 2. Redistributions in binary form must reproduce the above copyright 48 * notice, this list of conditions and the following disclaimer in the 49 * documentation and/or other materials provided with the distribution. 50 * 3. All advertising materials mentioning features or use of this software 51 * must display the following acknowledgement: 52 * This product includes software developed by the University of 53 * California, Berkeley and its contributors. 54 * 4. Neither the name of the University nor the names of its contributors 55 * may be used to endorse or promote products derived from this software 56 * without specific prior written permission. 57 * 58 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 59 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 60 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 61 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 62 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 63 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 64 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 65 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 66 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 67 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 68 * SUCH DAMAGE. 69 */ 70 71 /* 72 * External virtual filesystem routines 73 */ 74 75 #include <sys/param.h> 76 #include <sys/systm.h> 77 #include <sys/kernel.h> 78 #include <sys/malloc.h> 79 #include <sys/mount.h> 80 #include <sys/proc.h> 81 #include <sys/vnode.h> 82 #include <sys/buf.h> 83 #include <sys/eventhandler.h> 84 #include <sys/kthread.h> 85 #include <sys/sysctl.h> 86 87 #include <machine/limits.h> 88 89 #include <sys/buf2.h> 90 #include <sys/thread2.h> 91 #include <sys/sysref2.h> 92 93 #include <vm/vm.h> 94 #include <vm/vm_object.h> 95 96 struct mountscan_info { 97 TAILQ_ENTRY(mountscan_info) msi_entry; 98 int msi_how; 99 struct mount *msi_node; 100 }; 101 102 struct vmntvnodescan_info { 103 TAILQ_ENTRY(vmntvnodescan_info) entry; 104 struct vnode *vp; 105 }; 106 107 struct vnlru_info { 108 int pass; 109 }; 110 111 static int vnlru_nowhere = 0; 112 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RD, 113 &vnlru_nowhere, 0, 114 "Number of times the vnlru process ran without success"); 115 116 117 static struct lwkt_token mntid_token; 118 static struct mount dummymount; 119 120 /* note: mountlist exported to pstat */ 121 struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist); 122 static TAILQ_HEAD(,mountscan_info) mountscan_list; 123 static struct lwkt_token mountlist_token; 124 static TAILQ_HEAD(,vmntvnodescan_info) mntvnodescan_list; 125 struct lwkt_token mntvnode_token; 126 127 static TAILQ_HEAD(,bio_ops) bio_ops_list = TAILQ_HEAD_INITIALIZER(bio_ops_list); 128 129 /* 130 * Called from vfsinit() 131 */ 132 void 133 vfs_mount_init(void) 134 { 135 lwkt_token_init(&mountlist_token, "mntlist"); 136 lwkt_token_init(&mntvnode_token, "mntvnode"); 137 lwkt_token_init(&mntid_token, "mntid"); 138 TAILQ_INIT(&mountscan_list); 139 TAILQ_INIT(&mntvnodescan_list); 140 mount_init(&dummymount); 141 dummymount.mnt_flag |= MNT_RDONLY; 142 dummymount.mnt_kern_flag |= MNTK_ALL_MPSAFE; 143 } 144 145 /* 146 * Support function called with mntvnode_token held to remove a vnode 147 * from the mountlist. We must update any list scans which are in progress. 148 */ 149 static void 150 vremovevnodemnt(struct vnode *vp) 151 { 152 struct vmntvnodescan_info *info; 153 154 TAILQ_FOREACH(info, &mntvnodescan_list, entry) { 155 if (info->vp == vp) 156 info->vp = TAILQ_NEXT(vp, v_nmntvnodes); 157 } 158 TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes); 159 } 160 161 /* 162 * Allocate a new vnode and associate it with a tag, mount point, and 163 * operations vector. 164 * 165 * A VX locked and refd vnode is returned. The caller should setup the 166 * remaining fields and vx_put() or, if he wishes to leave a vref, 167 * vx_unlock() the vnode. 168 */ 169 int 170 getnewvnode(enum vtagtype tag, struct mount *mp, 171 struct vnode **vpp, int lktimeout, int lkflags) 172 { 173 struct vnode *vp; 174 175 KKASSERT(mp != NULL); 176 177 vp = allocvnode(lktimeout, lkflags); 178 vp->v_tag = tag; 179 vp->v_data = NULL; 180 181 /* 182 * By default the vnode is assigned the mount point's normal 183 * operations vector. 184 */ 185 vp->v_ops = &mp->mnt_vn_use_ops; 186 187 /* 188 * Placing the vnode on the mount point's queue makes it visible. 189 * VNON prevents it from being messed with, however. 190 */ 191 insmntque(vp, mp); 192 193 /* 194 * A VX locked & refd vnode is returned. 195 */ 196 *vpp = vp; 197 return (0); 198 } 199 200 /* 201 * This function creates vnodes with special operations vectors. The 202 * mount point is optional. 203 * 204 * This routine is being phased out but is still used by vfs_conf to 205 * create vnodes for devices prior to the root mount (with mp == NULL). 206 */ 207 int 208 getspecialvnode(enum vtagtype tag, struct mount *mp, 209 struct vop_ops **ops, 210 struct vnode **vpp, int lktimeout, int lkflags) 211 { 212 struct vnode *vp; 213 214 vp = allocvnode(lktimeout, lkflags); 215 vp->v_tag = tag; 216 vp->v_data = NULL; 217 vp->v_ops = ops; 218 219 if (mp == NULL) 220 mp = &dummymount; 221 222 /* 223 * Placing the vnode on the mount point's queue makes it visible. 224 * VNON prevents it from being messed with, however. 225 */ 226 insmntque(vp, mp); 227 228 /* 229 * A VX locked & refd vnode is returned. 230 */ 231 *vpp = vp; 232 return (0); 233 } 234 235 /* 236 * Interlock against an unmount, return 0 on success, non-zero on failure. 237 * 238 * The passed flag may be 0 or LK_NOWAIT and is only used if an unmount 239 * is in-progress. 240 * 241 * If no unmount is in-progress LK_NOWAIT is ignored. No other flag bits 242 * are used. A shared locked will be obtained and the filesystem will not 243 * be unmountable until the lock is released. 244 */ 245 int 246 vfs_busy(struct mount *mp, int flags) 247 { 248 int lkflags; 249 250 atomic_add_int(&mp->mnt_refs, 1); 251 if (mp->mnt_kern_flag & MNTK_UNMOUNT) { 252 if (flags & LK_NOWAIT) { 253 atomic_add_int(&mp->mnt_refs, -1); 254 return (ENOENT); 255 } 256 /* XXX not MP safe */ 257 mp->mnt_kern_flag |= MNTK_MWAIT; 258 /* 259 * Since all busy locks are shared except the exclusive 260 * lock granted when unmounting, the only place that a 261 * wakeup needs to be done is at the release of the 262 * exclusive lock at the end of dounmount. 263 */ 264 tsleep((caddr_t)mp, 0, "vfs_busy", 0); 265 atomic_add_int(&mp->mnt_refs, -1); 266 return (ENOENT); 267 } 268 lkflags = LK_SHARED; 269 if (lockmgr(&mp->mnt_lock, lkflags)) 270 panic("vfs_busy: unexpected lock failure"); 271 return (0); 272 } 273 274 /* 275 * Free a busy filesystem. 276 * 277 * Decrement refs before releasing the lock so e.g. a pending umount 278 * doesn't give us an unexpected busy error. 279 */ 280 void 281 vfs_unbusy(struct mount *mp) 282 { 283 atomic_add_int(&mp->mnt_refs, -1); 284 lockmgr(&mp->mnt_lock, LK_RELEASE); 285 } 286 287 /* 288 * Lookup a filesystem type, and if found allocate and initialize 289 * a mount structure for it. 290 * 291 * Devname is usually updated by mount(8) after booting. 292 */ 293 int 294 vfs_rootmountalloc(char *fstypename, char *devname, struct mount **mpp) 295 { 296 struct vfsconf *vfsp; 297 struct mount *mp; 298 299 if (fstypename == NULL) 300 return (ENODEV); 301 302 vfsp = vfsconf_find_by_name(fstypename); 303 if (vfsp == NULL) 304 return (ENODEV); 305 mp = kmalloc(sizeof(struct mount), M_MOUNT, M_WAITOK | M_ZERO); 306 mount_init(mp); 307 lockinit(&mp->mnt_lock, "vfslock", VLKTIMEOUT, 0); 308 309 vfs_busy(mp, 0); 310 mp->mnt_vfc = vfsp; 311 mp->mnt_op = vfsp->vfc_vfsops; 312 vfsp->vfc_refcount++; 313 mp->mnt_stat.f_type = vfsp->vfc_typenum; 314 mp->mnt_flag |= MNT_RDONLY; 315 mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK; 316 strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN); 317 copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0); 318 *mpp = mp; 319 return (0); 320 } 321 322 /* 323 * Basic mount structure initialization 324 */ 325 void 326 mount_init(struct mount *mp) 327 { 328 lockinit(&mp->mnt_lock, "vfslock", 0, 0); 329 lwkt_token_init(&mp->mnt_token, "permnt"); 330 331 TAILQ_INIT(&mp->mnt_nvnodelist); 332 TAILQ_INIT(&mp->mnt_reservedvnlist); 333 TAILQ_INIT(&mp->mnt_jlist); 334 mp->mnt_nvnodelistsize = 0; 335 mp->mnt_flag = 0; 336 mp->mnt_iosize_max = MAXPHYS; 337 } 338 339 /* 340 * Lookup a mount point by filesystem identifier. 341 */ 342 struct mount * 343 vfs_getvfs(fsid_t *fsid) 344 { 345 struct mount *mp; 346 347 lwkt_gettoken(&mountlist_token); 348 TAILQ_FOREACH(mp, &mountlist, mnt_list) { 349 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] && 350 mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) { 351 break; 352 } 353 } 354 lwkt_reltoken(&mountlist_token); 355 return (mp); 356 } 357 358 /* 359 * Get a new unique fsid. Try to make its val[0] unique, since this value 360 * will be used to create fake device numbers for stat(). Also try (but 361 * not so hard) make its val[0] unique mod 2^16, since some emulators only 362 * support 16-bit device numbers. We end up with unique val[0]'s for the 363 * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls. 364 * 365 * Keep in mind that several mounts may be running in parallel. Starting 366 * the search one past where the previous search terminated is both a 367 * micro-optimization and a defense against returning the same fsid to 368 * different mounts. 369 */ 370 void 371 vfs_getnewfsid(struct mount *mp) 372 { 373 static u_int16_t mntid_base; 374 fsid_t tfsid; 375 int mtype; 376 377 lwkt_gettoken(&mntid_token); 378 mtype = mp->mnt_vfc->vfc_typenum; 379 tfsid.val[1] = mtype; 380 mtype = (mtype & 0xFF) << 24; 381 for (;;) { 382 tfsid.val[0] = makeudev(255, 383 mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF)); 384 mntid_base++; 385 if (vfs_getvfs(&tfsid) == NULL) 386 break; 387 } 388 mp->mnt_stat.f_fsid.val[0] = tfsid.val[0]; 389 mp->mnt_stat.f_fsid.val[1] = tfsid.val[1]; 390 lwkt_reltoken(&mntid_token); 391 } 392 393 /* 394 * Set the FSID for a new mount point to the template. Adjust 395 * the FSID to avoid collisions. 396 */ 397 int 398 vfs_setfsid(struct mount *mp, fsid_t *template) 399 { 400 int didmunge = 0; 401 402 bzero(&mp->mnt_stat.f_fsid, sizeof(mp->mnt_stat.f_fsid)); 403 for (;;) { 404 if (vfs_getvfs(template) == NULL) 405 break; 406 didmunge = 1; 407 ++template->val[1]; 408 } 409 mp->mnt_stat.f_fsid = *template; 410 return(didmunge); 411 } 412 413 /* 414 * This routine is called when we have too many vnodes. It attempts 415 * to free <count> vnodes and will potentially free vnodes that still 416 * have VM backing store (VM backing store is typically the cause 417 * of a vnode blowout so we want to do this). Therefore, this operation 418 * is not considered cheap. 419 * 420 * A number of conditions may prevent a vnode from being reclaimed. 421 * the buffer cache may have references on the vnode, a directory 422 * vnode may still have references due to the namei cache representing 423 * underlying files, or the vnode may be in active use. It is not 424 * desireable to reuse such vnodes. These conditions may cause the 425 * number of vnodes to reach some minimum value regardless of what 426 * you set kern.maxvnodes to. Do not set kern.maxvnodes too low. 427 */ 428 429 /* 430 * This is a quick non-blocking check to determine if the vnode is a good 431 * candidate for being (eventually) vgone()'d. Returns 0 if the vnode is 432 * not a good candidate, 1 if it is. 433 */ 434 static __inline int 435 vmightfree(struct vnode *vp, int page_count, int pass) 436 { 437 if (vp->v_flag & VRECLAIMED) 438 return (0); 439 #if 0 440 if ((vp->v_flag & VFREE) && TAILQ_EMPTY(&vp->v_namecache)) 441 return (0); 442 #endif 443 if (sysref_isactive(&vp->v_sysref)) 444 return (0); 445 if (vp->v_object && vp->v_object->resident_page_count >= page_count) 446 return (0); 447 448 /* 449 * XXX horrible hack. Up to four passes will be taken. Each pass 450 * makes a larger set of vnodes eligible. For now what this really 451 * means is that we try to recycle files opened only once before 452 * recycling files opened multiple times. 453 */ 454 switch(vp->v_flag & (VAGE0 | VAGE1)) { 455 case 0: 456 if (pass < 3) 457 return(0); 458 break; 459 case VAGE0: 460 if (pass < 2) 461 return(0); 462 break; 463 case VAGE1: 464 if (pass < 1) 465 return(0); 466 break; 467 case VAGE0 | VAGE1: 468 break; 469 } 470 return (1); 471 } 472 473 /* 474 * The vnode was found to be possibly vgone()able and the caller has locked it 475 * (thus the usecount should be 1 now). Determine if the vnode is actually 476 * vgone()able, doing some cleanups in the process. Returns 1 if the vnode 477 * can be vgone()'d, 0 otherwise. 478 * 479 * Note that v_auxrefs may be non-zero because (A) this vnode is not a leaf 480 * in the namecache topology and (B) this vnode has buffer cache bufs. 481 * We cannot remove vnodes with non-leaf namecache associations. We do a 482 * tentitive leaf check prior to attempting to flush out any buffers but the 483 * 'real' test when all is said in done is that v_auxrefs must become 0 for 484 * the vnode to be freeable. 485 * 486 * We could theoretically just unconditionally flush when v_auxrefs != 0, 487 * but flushing data associated with non-leaf nodes (which are always 488 * directories), just throws it away for no benefit. It is the buffer 489 * cache's responsibility to choose buffers to recycle from the cached 490 * data point of view. 491 */ 492 static int 493 visleaf(struct vnode *vp) 494 { 495 struct namecache *ncp; 496 497 spin_lock(&vp->v_spin); 498 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 499 if (!TAILQ_EMPTY(&ncp->nc_list)) { 500 spin_unlock(&vp->v_spin); 501 return(0); 502 } 503 } 504 spin_unlock(&vp->v_spin); 505 return(1); 506 } 507 508 /* 509 * Try to clean up the vnode to the point where it can be vgone()'d, returning 510 * 0 if it cannot be vgone()'d (or already has been), 1 if it can. Unlike 511 * vmightfree() this routine may flush the vnode and block. Vnodes marked 512 * VFREE are still candidates for vgone()ing because they may hold namecache 513 * resources and could be blocking the namecache directory hierarchy (and 514 * related vnodes) from being freed. 515 */ 516 static int 517 vtrytomakegoneable(struct vnode *vp, int page_count) 518 { 519 if (vp->v_flag & VRECLAIMED) 520 return (0); 521 if (vp->v_sysref.refcnt > 1) 522 return (0); 523 if (vp->v_object && vp->v_object->resident_page_count >= page_count) 524 return (0); 525 if (vp->v_auxrefs && visleaf(vp)) { 526 vinvalbuf(vp, V_SAVE, 0, 0); 527 #if 0 /* DEBUG */ 528 kprintf((vp->v_auxrefs ? "vrecycle: vp %p failed: %s\n" : 529 "vrecycle: vp %p succeeded: %s\n"), vp, 530 (TAILQ_FIRST(&vp->v_namecache) ? 531 TAILQ_FIRST(&vp->v_namecache)->nc_name : "?")); 532 #endif 533 } 534 535 /* 536 * This sequence may seem a little strange, but we need to optimize 537 * the critical path a bit. We can't recycle vnodes with other 538 * references and because we are trying to recycle an otherwise 539 * perfectly fine vnode we have to invalidate the namecache in a 540 * way that avoids possible deadlocks (since the vnode lock is being 541 * held here). Finally, we have to check for other references one 542 * last time in case something snuck in during the inval. 543 */ 544 if (vp->v_sysref.refcnt > 1 || vp->v_auxrefs != 0) 545 return (0); 546 if (cache_inval_vp_nonblock(vp)) 547 return (0); 548 return (vp->v_sysref.refcnt <= 1 && vp->v_auxrefs == 0); 549 } 550 551 /* 552 * Reclaim up to 1/10 of the vnodes associated with a mount point. Try 553 * to avoid vnodes which have lots of resident pages (we are trying to free 554 * vnodes, not memory). 555 * 556 * This routine is a callback from the mountlist scan. The mount point 557 * in question will be busied. 558 * 559 * NOTE: The 1/10 reclamation also ensures that the inactive data set 560 * (the vnodes being recycled by the one-time use) does not degenerate 561 * into too-small a set. This is important because once a vnode is 562 * marked as not being one-time-use (VAGE0/VAGE1 both 0) that vnode 563 * will not be destroyed EXCEPT by this mechanism. VM pages can still 564 * be cleaned/freed by the pageout daemon. 565 */ 566 static int 567 vlrureclaim(struct mount *mp, void *data) 568 { 569 struct vnlru_info *info = data; 570 struct vnode *vp; 571 int done; 572 int trigger; 573 int usevnodes; 574 int count; 575 int trigger_mult = vnlru_nowhere; 576 577 /* 578 * Calculate the trigger point for the resident pages check. The 579 * minimum trigger value is approximately the number of pages in 580 * the system divded by the number of vnodes. However, due to 581 * various other system memory overheads unrelated to data caching 582 * it is a good idea to double the trigger (at least). 583 * 584 * trigger_mult starts at 0. If the recycler is having problems 585 * finding enough freeable vnodes it will increase trigger_mult. 586 * This should not happen in normal operation, even on machines with 587 * low amounts of memory, but extraordinary memory use by the system 588 * verses the amount of cached data can trigger it. 589 */ 590 usevnodes = desiredvnodes; 591 if (usevnodes <= 0) 592 usevnodes = 1; 593 trigger = vmstats.v_page_count * (trigger_mult + 2) / usevnodes; 594 595 done = 0; 596 lwkt_gettoken(&mntvnode_token); 597 count = mp->mnt_nvnodelistsize / 10 + 1; 598 599 while (count && mp->mnt_syncer) { 600 /* 601 * Next vnode. Use the special syncer vnode to placemark 602 * the LRU. This way the LRU code does not interfere with 603 * vmntvnodescan(). 604 */ 605 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes); 606 TAILQ_REMOVE(&mp->mnt_nvnodelist, mp->mnt_syncer, v_nmntvnodes); 607 if (vp) { 608 TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp, 609 mp->mnt_syncer, v_nmntvnodes); 610 } else { 611 TAILQ_INSERT_HEAD(&mp->mnt_nvnodelist, mp->mnt_syncer, 612 v_nmntvnodes); 613 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes); 614 if (vp == NULL) 615 break; 616 } 617 618 /* 619 * __VNODESCAN__ 620 * 621 * The VP will stick around while we hold mntvnode_token, 622 * at least until we block, so we can safely do an initial 623 * check, and then must check again after we lock the vnode. 624 */ 625 if (vp->v_type == VNON || /* syncer or indeterminant */ 626 !vmightfree(vp, trigger, info->pass) /* critical path opt */ 627 ) { 628 --count; 629 continue; 630 } 631 632 /* 633 * VX get the candidate vnode. If the VX get fails the 634 * vnode might still be on the mountlist. Our loop depends 635 * on us at least cycling the vnode to the end of the 636 * mountlist. 637 */ 638 if (vx_get_nonblock(vp) != 0) { 639 --count; 640 continue; 641 } 642 643 /* 644 * Since we blocked locking the vp, make sure it is still 645 * a candidate for reclamation. That is, it has not already 646 * been reclaimed and only has our VX reference associated 647 * with it. 648 */ 649 if (vp->v_type == VNON || /* syncer or indeterminant */ 650 (vp->v_flag & VRECLAIMED) || 651 vp->v_mount != mp || 652 !vtrytomakegoneable(vp, trigger) /* critical path opt */ 653 ) { 654 --count; 655 vx_put(vp); 656 continue; 657 } 658 659 /* 660 * All right, we are good, move the vp to the end of the 661 * mountlist and clean it out. The vget will have returned 662 * an error if the vnode was destroyed (VRECLAIMED set), so we 663 * do not have to check again. The vput() will move the 664 * vnode to the free list if the vgone() was successful. 665 */ 666 KKASSERT(vp->v_mount == mp); 667 vgone_vxlocked(vp); 668 vx_put(vp); 669 ++done; 670 --count; 671 } 672 lwkt_reltoken(&mntvnode_token); 673 return (done); 674 } 675 676 /* 677 * Attempt to recycle vnodes in a context that is always safe to block. 678 * Calling vlrurecycle() from the bowels of file system code has some 679 * interesting deadlock problems. 680 */ 681 static struct thread *vnlruthread; 682 683 static void 684 vnlru_proc(void) 685 { 686 struct thread *td = curthread; 687 struct vnlru_info info; 688 int done; 689 690 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td, 691 SHUTDOWN_PRI_FIRST); 692 693 for (;;) { 694 kproc_suspend_loop(); 695 696 /* 697 * Do some opportunistic roving. 698 */ 699 if (numvnodes > 100000) 700 vnode_free_rover_scan(50); 701 else if (numvnodes > 10000) 702 vnode_free_rover_scan(20); 703 else 704 vnode_free_rover_scan(5); 705 706 /* 707 * Try to free some vnodes if we have too many 708 */ 709 if (numvnodes > desiredvnodes && 710 freevnodes > desiredvnodes * 2 / 10) { 711 int count = numvnodes - desiredvnodes; 712 713 if (count > freevnodes / 100) 714 count = freevnodes / 100; 715 if (count < 5) 716 count = 5; 717 freesomevnodes(count); 718 } 719 720 /* 721 * Nothing to do if most of our vnodes are already on 722 * the free list. 723 */ 724 if (numvnodes - freevnodes <= desiredvnodes * 9 / 10) { 725 tsleep(vnlruthread, 0, "vlruwt", hz); 726 continue; 727 } 728 cache_hysteresis(); 729 730 /* 731 * The pass iterates through the four combinations of 732 * VAGE0/VAGE1. We want to get rid of aged small files 733 * first. 734 */ 735 info.pass = 0; 736 done = 0; 737 while (done == 0 && info.pass < 4) { 738 done = mountlist_scan(vlrureclaim, &info, 739 MNTSCAN_FORWARD); 740 ++info.pass; 741 } 742 743 /* 744 * The vlrureclaim() call only processes 1/10 of the vnodes 745 * on each mount. If we couldn't find any repeat the loop 746 * at least enough times to cover all available vnodes before 747 * we start sleeping. Complain if the failure extends past 748 * 30 second, every 30 seconds. 749 */ 750 if (done == 0) { 751 ++vnlru_nowhere; 752 if (vnlru_nowhere % 10 == 0) 753 tsleep(vnlruthread, 0, "vlrup", hz * 3); 754 if (vnlru_nowhere % 100 == 0) 755 kprintf("vnlru_proc: vnode recycler stopped working!\n"); 756 if (vnlru_nowhere == 1000) 757 vnlru_nowhere = 900; 758 } else { 759 vnlru_nowhere = 0; 760 } 761 } 762 } 763 764 /* 765 * MOUNTLIST FUNCTIONS 766 */ 767 768 /* 769 * mountlist_insert (MP SAFE) 770 * 771 * Add a new mount point to the mount list. 772 */ 773 void 774 mountlist_insert(struct mount *mp, int how) 775 { 776 lwkt_gettoken(&mountlist_token); 777 if (how == MNTINS_FIRST) 778 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list); 779 else 780 TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list); 781 lwkt_reltoken(&mountlist_token); 782 } 783 784 /* 785 * mountlist_interlock (MP SAFE) 786 * 787 * Execute the specified interlock function with the mountlist token 788 * held. The function will be called in a serialized fashion verses 789 * other functions called through this mechanism. 790 */ 791 int 792 mountlist_interlock(int (*callback)(struct mount *), struct mount *mp) 793 { 794 int error; 795 796 lwkt_gettoken(&mountlist_token); 797 error = callback(mp); 798 lwkt_reltoken(&mountlist_token); 799 return (error); 800 } 801 802 /* 803 * mountlist_boot_getfirst (DURING BOOT ONLY) 804 * 805 * This function returns the first mount on the mountlist, which is 806 * expected to be the root mount. Since no interlocks are obtained 807 * this function is only safe to use during booting. 808 */ 809 810 struct mount * 811 mountlist_boot_getfirst(void) 812 { 813 return(TAILQ_FIRST(&mountlist)); 814 } 815 816 /* 817 * mountlist_remove (MP SAFE) 818 * 819 * Remove a node from the mountlist. If this node is the next scan node 820 * for any active mountlist scans, the active mountlist scan will be 821 * adjusted to skip the node, thus allowing removals during mountlist 822 * scans. 823 */ 824 void 825 mountlist_remove(struct mount *mp) 826 { 827 struct mountscan_info *msi; 828 829 lwkt_gettoken(&mountlist_token); 830 TAILQ_FOREACH(msi, &mountscan_list, msi_entry) { 831 if (msi->msi_node == mp) { 832 if (msi->msi_how & MNTSCAN_FORWARD) 833 msi->msi_node = TAILQ_NEXT(mp, mnt_list); 834 else 835 msi->msi_node = TAILQ_PREV(mp, mntlist, mnt_list); 836 } 837 } 838 TAILQ_REMOVE(&mountlist, mp, mnt_list); 839 lwkt_reltoken(&mountlist_token); 840 } 841 842 /* 843 * mountlist_exists (MP SAFE) 844 * 845 * Checks if a node exists in the mountlist. 846 * This function is mainly used by VFS quota code to check if a 847 * cached nullfs struct mount pointer is still valid at use time 848 * 849 * FIXME: there is no warranty the mp passed to that function 850 * will be the same one used by VFS_ACCOUNT() later 851 */ 852 int 853 mountlist_exists(struct mount *mp) 854 { 855 int node_exists = 0; 856 struct mount* lmp; 857 858 lwkt_gettoken(&mountlist_token); 859 TAILQ_FOREACH(lmp, &mountlist, mnt_list) { 860 if (lmp == mp) { 861 node_exists = 1; 862 break; 863 } 864 } 865 lwkt_reltoken(&mountlist_token); 866 return(node_exists); 867 } 868 869 /* 870 * mountlist_scan (MP SAFE) 871 * 872 * Safely scan the mount points on the mount list. Unless otherwise 873 * specified each mount point will be busied prior to the callback and 874 * unbusied afterwords. The callback may safely remove any mount point 875 * without interfering with the scan. If the current callback 876 * mount is removed the scanner will not attempt to unbusy it. 877 * 878 * If a mount node cannot be busied it is silently skipped. 879 * 880 * The callback return value is aggregated and a total is returned. A return 881 * value of < 0 is not aggregated and will terminate the scan. 882 * 883 * MNTSCAN_FORWARD - the mountlist is scanned in the forward direction 884 * MNTSCAN_REVERSE - the mountlist is scanned in reverse 885 * MNTSCAN_NOBUSY - the scanner will make the callback without busying 886 * the mount node. 887 */ 888 int 889 mountlist_scan(int (*callback)(struct mount *, void *), void *data, int how) 890 { 891 struct mountscan_info info; 892 struct mount *mp; 893 int count; 894 int res; 895 896 lwkt_gettoken(&mountlist_token); 897 898 info.msi_how = how; 899 info.msi_node = NULL; /* paranoia */ 900 TAILQ_INSERT_TAIL(&mountscan_list, &info, msi_entry); 901 902 res = 0; 903 904 if (how & MNTSCAN_FORWARD) { 905 info.msi_node = TAILQ_FIRST(&mountlist); 906 while ((mp = info.msi_node) != NULL) { 907 if (how & MNTSCAN_NOBUSY) { 908 count = callback(mp, data); 909 } else if (vfs_busy(mp, LK_NOWAIT) == 0) { 910 count = callback(mp, data); 911 if (mp == info.msi_node) 912 vfs_unbusy(mp); 913 } else { 914 count = 0; 915 } 916 if (count < 0) 917 break; 918 res += count; 919 if (mp == info.msi_node) 920 info.msi_node = TAILQ_NEXT(mp, mnt_list); 921 } 922 } else if (how & MNTSCAN_REVERSE) { 923 info.msi_node = TAILQ_LAST(&mountlist, mntlist); 924 while ((mp = info.msi_node) != NULL) { 925 if (how & MNTSCAN_NOBUSY) { 926 count = callback(mp, data); 927 } else if (vfs_busy(mp, LK_NOWAIT) == 0) { 928 count = callback(mp, data); 929 if (mp == info.msi_node) 930 vfs_unbusy(mp); 931 } else { 932 count = 0; 933 } 934 if (count < 0) 935 break; 936 res += count; 937 if (mp == info.msi_node) 938 info.msi_node = TAILQ_PREV(mp, mntlist, mnt_list); 939 } 940 } 941 TAILQ_REMOVE(&mountscan_list, &info, msi_entry); 942 lwkt_reltoken(&mountlist_token); 943 return(res); 944 } 945 946 /* 947 * MOUNT RELATED VNODE FUNCTIONS 948 */ 949 950 static struct kproc_desc vnlru_kp = { 951 "vnlru", 952 vnlru_proc, 953 &vnlruthread 954 }; 955 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp) 956 957 /* 958 * Move a vnode from one mount queue to another. 959 * 960 * MPSAFE 961 */ 962 void 963 insmntque(struct vnode *vp, struct mount *mp) 964 { 965 lwkt_gettoken(&mntvnode_token); 966 /* 967 * Delete from old mount point vnode list, if on one. 968 */ 969 if (vp->v_mount != NULL) { 970 KASSERT(vp->v_mount->mnt_nvnodelistsize > 0, 971 ("bad mount point vnode list size")); 972 vremovevnodemnt(vp); 973 vp->v_mount->mnt_nvnodelistsize--; 974 } 975 /* 976 * Insert into list of vnodes for the new mount point, if available. 977 * The 'end' of the LRU list is the vnode prior to mp->mnt_syncer. 978 */ 979 if ((vp->v_mount = mp) == NULL) { 980 lwkt_reltoken(&mntvnode_token); 981 return; 982 } 983 if (mp->mnt_syncer) { 984 TAILQ_INSERT_BEFORE(mp->mnt_syncer, vp, v_nmntvnodes); 985 } else { 986 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes); 987 } 988 mp->mnt_nvnodelistsize++; 989 lwkt_reltoken(&mntvnode_token); 990 } 991 992 993 /* 994 * Scan the vnodes under a mount point and issue appropriate callbacks. 995 * 996 * The fastfunc() callback is called with just the mountlist token held 997 * (no vnode lock). It may not block and the vnode may be undergoing 998 * modifications while the caller is processing it. The vnode will 999 * not be entirely destroyed, however, due to the fact that the mountlist 1000 * token is held. A return value < 0 skips to the next vnode without calling 1001 * the slowfunc(), a return value > 0 terminates the loop. 1002 * 1003 * The slowfunc() callback is called after the vnode has been successfully 1004 * locked based on passed flags. The vnode is skipped if it gets rearranged 1005 * or destroyed while blocking on the lock. A non-zero return value from 1006 * the slow function terminates the loop. The slow function is allowed to 1007 * arbitrarily block. The scanning code guarentees consistency of operation 1008 * even if the slow function deletes or moves the node, or blocks and some 1009 * other thread deletes or moves the node. 1010 * 1011 * NOTE: We hold vmobj_token to prevent a VM object from being destroyed 1012 * out from under the fastfunc()'s vnode test. It will not prevent 1013 * v_object from getting NULL'd out but it will ensure that the 1014 * pointer (if we race) will remain stable. 1015 */ 1016 int 1017 vmntvnodescan( 1018 struct mount *mp, 1019 int flags, 1020 int (*fastfunc)(struct mount *mp, struct vnode *vp, void *data), 1021 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data), 1022 void *data 1023 ) { 1024 struct vmntvnodescan_info info; 1025 struct vnode *vp; 1026 int r = 0; 1027 int maxcount = mp->mnt_nvnodelistsize * 2; 1028 int stopcount = 0; 1029 int count = 0; 1030 1031 lwkt_gettoken(&mntvnode_token); 1032 lwkt_gettoken(&vmobj_token); 1033 1034 /* 1035 * If asked to do one pass stop after iterating available vnodes. 1036 * Under heavy loads new vnodes can be added while we are scanning, 1037 * so this isn't perfect. Create a slop factor of 2x. 1038 */ 1039 if (flags & VMSC_ONEPASS) 1040 stopcount = mp->mnt_nvnodelistsize; 1041 1042 info.vp = TAILQ_FIRST(&mp->mnt_nvnodelist); 1043 TAILQ_INSERT_TAIL(&mntvnodescan_list, &info, entry); 1044 while ((vp = info.vp) != NULL) { 1045 if (--maxcount == 0) { 1046 kprintf("Warning: excessive fssync iteration\n"); 1047 maxcount = mp->mnt_nvnodelistsize * 2; 1048 } 1049 1050 /* 1051 * Skip if visible but not ready, or special (e.g. 1052 * mp->mnt_syncer) 1053 */ 1054 if (vp->v_type == VNON) 1055 goto next; 1056 KKASSERT(vp->v_mount == mp); 1057 1058 /* 1059 * Quick test. A negative return continues the loop without 1060 * calling the slow test. 0 continues onto the slow test. 1061 * A positive number aborts the loop. 1062 */ 1063 if (fastfunc) { 1064 if ((r = fastfunc(mp, vp, data)) < 0) { 1065 r = 0; 1066 goto next; 1067 } 1068 if (r) 1069 break; 1070 } 1071 1072 /* 1073 * Get a vxlock on the vnode, retry if it has moved or isn't 1074 * in the mountlist where we expect it. 1075 */ 1076 if (slowfunc) { 1077 int error; 1078 1079 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) { 1080 case VMSC_GETVP: 1081 error = vget(vp, LK_EXCLUSIVE); 1082 break; 1083 case VMSC_GETVP|VMSC_NOWAIT: 1084 error = vget(vp, LK_EXCLUSIVE|LK_NOWAIT); 1085 break; 1086 case VMSC_GETVX: 1087 vx_get(vp); 1088 error = 0; 1089 break; 1090 default: 1091 error = 0; 1092 break; 1093 } 1094 if (error) 1095 goto next; 1096 /* 1097 * Do not call the slow function if the vnode is 1098 * invalid or if it was ripped out from under us 1099 * while we (potentially) blocked. 1100 */ 1101 if (info.vp == vp && vp->v_type != VNON) 1102 r = slowfunc(mp, vp, data); 1103 1104 /* 1105 * Cleanup 1106 */ 1107 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) { 1108 case VMSC_GETVP: 1109 case VMSC_GETVP|VMSC_NOWAIT: 1110 vput(vp); 1111 break; 1112 case VMSC_GETVX: 1113 vx_put(vp); 1114 break; 1115 default: 1116 break; 1117 } 1118 if (r != 0) 1119 break; 1120 } 1121 1122 next: 1123 /* 1124 * Yield after some processing. Depending on the number 1125 * of vnodes, we might wind up running for a long time. 1126 * Because threads are not preemptable, time critical 1127 * userland processes might starve. Give them a chance 1128 * now and then. 1129 */ 1130 if (++count == 10000) { 1131 /* We really want to yield a bit, so we simply sleep a tick */ 1132 tsleep(mp, 0, "vnodescn", 1); 1133 count = 0; 1134 } 1135 1136 /* 1137 * If doing one pass this decrements to zero. If it starts 1138 * at zero it is effectively unlimited for the purposes of 1139 * this loop. 1140 */ 1141 if (--stopcount == 0) 1142 break; 1143 1144 /* 1145 * Iterate. If the vnode was ripped out from under us 1146 * info.vp will already point to the next vnode, otherwise 1147 * we have to obtain the next valid vnode ourselves. 1148 */ 1149 if (info.vp == vp) 1150 info.vp = TAILQ_NEXT(vp, v_nmntvnodes); 1151 } 1152 TAILQ_REMOVE(&mntvnodescan_list, &info, entry); 1153 lwkt_reltoken(&vmobj_token); 1154 lwkt_reltoken(&mntvnode_token); 1155 return(r); 1156 } 1157 1158 /* 1159 * Remove any vnodes in the vnode table belonging to mount point mp. 1160 * 1161 * If FORCECLOSE is not specified, there should not be any active ones, 1162 * return error if any are found (nb: this is a user error, not a 1163 * system error). If FORCECLOSE is specified, detach any active vnodes 1164 * that are found. 1165 * 1166 * If WRITECLOSE is set, only flush out regular file vnodes open for 1167 * writing. 1168 * 1169 * SKIPSYSTEM causes any vnodes marked VSYSTEM to be skipped. 1170 * 1171 * `rootrefs' specifies the base reference count for the root vnode 1172 * of this filesystem. The root vnode is considered busy if its 1173 * v_sysref.refcnt exceeds this value. On a successful return, vflush() 1174 * will call vrele() on the root vnode exactly rootrefs times. 1175 * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must 1176 * be zero. 1177 */ 1178 #ifdef DIAGNOSTIC 1179 static int busyprt = 0; /* print out busy vnodes */ 1180 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, ""); 1181 #endif 1182 1183 static int vflush_scan(struct mount *mp, struct vnode *vp, void *data); 1184 1185 struct vflush_info { 1186 int flags; 1187 int busy; 1188 thread_t td; 1189 }; 1190 1191 int 1192 vflush(struct mount *mp, int rootrefs, int flags) 1193 { 1194 struct thread *td = curthread; /* XXX */ 1195 struct vnode *rootvp = NULL; 1196 int error; 1197 struct vflush_info vflush_info; 1198 1199 if (rootrefs > 0) { 1200 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0, 1201 ("vflush: bad args")); 1202 /* 1203 * Get the filesystem root vnode. We can vput() it 1204 * immediately, since with rootrefs > 0, it won't go away. 1205 */ 1206 if ((error = VFS_ROOT(mp, &rootvp)) != 0) { 1207 if ((flags & FORCECLOSE) == 0) 1208 return (error); 1209 rootrefs = 0; 1210 /* continue anyway */ 1211 } 1212 if (rootrefs) 1213 vput(rootvp); 1214 } 1215 1216 vflush_info.busy = 0; 1217 vflush_info.flags = flags; 1218 vflush_info.td = td; 1219 vmntvnodescan(mp, VMSC_GETVX, NULL, vflush_scan, &vflush_info); 1220 1221 if (rootrefs > 0 && (flags & FORCECLOSE) == 0) { 1222 /* 1223 * If just the root vnode is busy, and if its refcount 1224 * is equal to `rootrefs', then go ahead and kill it. 1225 */ 1226 KASSERT(vflush_info.busy > 0, ("vflush: not busy")); 1227 KASSERT(rootvp->v_sysref.refcnt >= rootrefs, ("vflush: rootrefs")); 1228 if (vflush_info.busy == 1 && rootvp->v_sysref.refcnt == rootrefs) { 1229 vx_lock(rootvp); 1230 vgone_vxlocked(rootvp); 1231 vx_unlock(rootvp); 1232 vflush_info.busy = 0; 1233 } 1234 } 1235 if (vflush_info.busy) 1236 return (EBUSY); 1237 for (; rootrefs > 0; rootrefs--) 1238 vrele(rootvp); 1239 return (0); 1240 } 1241 1242 /* 1243 * The scan callback is made with an VX locked vnode. 1244 */ 1245 static int 1246 vflush_scan(struct mount *mp, struct vnode *vp, void *data) 1247 { 1248 struct vflush_info *info = data; 1249 struct vattr vattr; 1250 int flags = info->flags; 1251 1252 /* 1253 * Skip over a vnodes marked VSYSTEM. 1254 */ 1255 if ((flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) { 1256 return(0); 1257 } 1258 1259 /* 1260 * Do not force-close VCHR or VBLK vnodes 1261 */ 1262 if (vp->v_type == VCHR || vp->v_type == VBLK) 1263 flags &= ~(WRITECLOSE|FORCECLOSE); 1264 1265 /* 1266 * If WRITECLOSE is set, flush out unlinked but still open 1267 * files (even if open only for reading) and regular file 1268 * vnodes open for writing. 1269 */ 1270 if ((flags & WRITECLOSE) && 1271 (vp->v_type == VNON || 1272 (VOP_GETATTR(vp, &vattr) == 0 && 1273 vattr.va_nlink > 0)) && 1274 (vp->v_writecount == 0 || vp->v_type != VREG)) { 1275 return(0); 1276 } 1277 1278 /* 1279 * If we are the only holder (refcnt of 1) or the vnode is in 1280 * termination (refcnt < 0), we can vgone the vnode. 1281 */ 1282 if (vp->v_sysref.refcnt <= 1) { 1283 vgone_vxlocked(vp); 1284 return(0); 1285 } 1286 1287 /* 1288 * If FORCECLOSE is set, forcibly destroy the vnode and then move 1289 * it to a dummymount structure so vop_*() functions don't deref 1290 * a NULL pointer. 1291 */ 1292 if (flags & FORCECLOSE) { 1293 vhold(vp); 1294 vgone_vxlocked(vp); 1295 if (vp->v_mount == NULL) 1296 insmntque(vp, &dummymount); 1297 vdrop(vp); 1298 return(0); 1299 } 1300 if (vp->v_type == VCHR || vp->v_type == VBLK) 1301 kprintf("vflush: Warning, cannot destroy busy device vnode\n"); 1302 #ifdef DIAGNOSTIC 1303 if (busyprt) 1304 vprint("vflush: busy vnode", vp); 1305 #endif 1306 ++info->busy; 1307 return(0); 1308 } 1309 1310 void 1311 add_bio_ops(struct bio_ops *ops) 1312 { 1313 TAILQ_INSERT_TAIL(&bio_ops_list, ops, entry); 1314 } 1315 1316 void 1317 rem_bio_ops(struct bio_ops *ops) 1318 { 1319 TAILQ_REMOVE(&bio_ops_list, ops, entry); 1320 } 1321 1322 /* 1323 * This calls the bio_ops io_sync function either for a mount point 1324 * or generally. 1325 * 1326 * WARNING: softdeps is weirdly coded and just isn't happy unless 1327 * io_sync is called with a NULL mount from the general syncing code. 1328 */ 1329 void 1330 bio_ops_sync(struct mount *mp) 1331 { 1332 struct bio_ops *ops; 1333 1334 if (mp) { 1335 if ((ops = mp->mnt_bioops) != NULL) 1336 ops->io_sync(mp); 1337 } else { 1338 TAILQ_FOREACH(ops, &bio_ops_list, entry) { 1339 ops->io_sync(NULL); 1340 } 1341 } 1342 } 1343 1344 /* 1345 * Lookup a mount point by nch 1346 */ 1347 struct mount * 1348 mount_get_by_nc(struct namecache *ncp) 1349 { 1350 struct mount *mp = NULL; 1351 1352 lwkt_gettoken(&mountlist_token); 1353 TAILQ_FOREACH(mp, &mountlist, mnt_list) { 1354 if (ncp == mp->mnt_ncmountpt.ncp) 1355 break; 1356 } 1357 lwkt_reltoken(&mountlist_token); 1358 return (mp); 1359 } 1360 1361