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 * $DragonFly: src/sys/kern/vfs_mount.c,v 1.37 2008/09/17 21:44:18 dillon Exp $ 71 */ 72 73 /* 74 * External virtual filesystem routines 75 */ 76 #include "opt_ddb.h" 77 78 #include <sys/param.h> 79 #include <sys/systm.h> 80 #include <sys/kernel.h> 81 #include <sys/malloc.h> 82 #include <sys/mount.h> 83 #include <sys/proc.h> 84 #include <sys/vnode.h> 85 #include <sys/buf.h> 86 #include <sys/eventhandler.h> 87 #include <sys/kthread.h> 88 #include <sys/sysctl.h> 89 90 #include <machine/limits.h> 91 92 #include <sys/buf2.h> 93 #include <sys/thread2.h> 94 #include <sys/sysref2.h> 95 96 #include <vm/vm.h> 97 #include <vm/vm_object.h> 98 99 struct mountscan_info { 100 TAILQ_ENTRY(mountscan_info) msi_entry; 101 int msi_how; 102 struct mount *msi_node; 103 }; 104 105 struct vmntvnodescan_info { 106 TAILQ_ENTRY(vmntvnodescan_info) entry; 107 struct vnode *vp; 108 }; 109 110 static int vnlru_nowhere = 0; 111 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RD, 112 &vnlru_nowhere, 0, 113 "Number of times the vnlru process ran without success"); 114 115 116 static struct lwkt_token mntid_token; 117 118 /* note: mountlist exported to pstat */ 119 struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist); 120 static TAILQ_HEAD(,mountscan_info) mountscan_list; 121 static struct lwkt_token mountlist_token; 122 static TAILQ_HEAD(,vmntvnodescan_info) mntvnodescan_list; 123 struct lwkt_token mntvnode_token; 124 125 static TAILQ_HEAD(,bio_ops) bio_ops_list = TAILQ_HEAD_INITIALIZER(bio_ops_list); 126 127 /* 128 * Called from vfsinit() 129 */ 130 void 131 vfs_mount_init(void) 132 { 133 lwkt_token_init(&mountlist_token); 134 lwkt_token_init(&mntvnode_token); 135 lwkt_token_init(&mntid_token); 136 TAILQ_INIT(&mountscan_list); 137 TAILQ_INIT(&mntvnodescan_list); 138 } 139 140 /* 141 * Support function called with mntvnode_token held to remove a vnode 142 * from the mountlist. We must update any list scans which are in progress. 143 */ 144 static void 145 vremovevnodemnt(struct vnode *vp) 146 { 147 struct vmntvnodescan_info *info; 148 149 TAILQ_FOREACH(info, &mntvnodescan_list, entry) { 150 if (info->vp == vp) 151 info->vp = TAILQ_NEXT(vp, v_nmntvnodes); 152 } 153 TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes); 154 } 155 156 /* 157 * Allocate a new vnode and associate it with a tag, mount point, and 158 * operations vector. 159 * 160 * A VX locked and refd vnode is returned. The caller should setup the 161 * remaining fields and vx_put() or, if he wishes to leave a vref, 162 * vx_unlock() the vnode. 163 */ 164 int 165 getnewvnode(enum vtagtype tag, struct mount *mp, 166 struct vnode **vpp, int lktimeout, int lkflags) 167 { 168 struct vnode *vp; 169 170 KKASSERT(mp != NULL); 171 172 vp = allocvnode(lktimeout, lkflags); 173 vp->v_tag = tag; 174 vp->v_data = NULL; 175 176 /* 177 * By default the vnode is assigned the mount point's normal 178 * operations vector. 179 */ 180 vp->v_ops = &mp->mnt_vn_use_ops; 181 182 /* 183 * Placing the vnode on the mount point's queue makes it visible. 184 * VNON prevents it from being messed with, however. 185 */ 186 insmntque(vp, mp); 187 188 /* 189 * A VX locked & refd vnode is returned. 190 */ 191 *vpp = vp; 192 return (0); 193 } 194 195 /* 196 * This function creates vnodes with special operations vectors. The 197 * mount point is optional. 198 * 199 * This routine is being phased out. 200 */ 201 int 202 getspecialvnode(enum vtagtype tag, struct mount *mp, 203 struct vop_ops **ops, 204 struct vnode **vpp, int lktimeout, int lkflags) 205 { 206 struct vnode *vp; 207 208 vp = allocvnode(lktimeout, lkflags); 209 vp->v_tag = tag; 210 vp->v_data = NULL; 211 vp->v_ops = ops; 212 213 /* 214 * Placing the vnode on the mount point's queue makes it visible. 215 * VNON prevents it from being messed with, however. 216 */ 217 insmntque(vp, mp); 218 219 /* 220 * A VX locked & refd vnode is returned. 221 */ 222 *vpp = vp; 223 return (0); 224 } 225 226 /* 227 * Interlock against an unmount, return 0 on success, non-zero on failure. 228 * 229 * The passed flag may be 0 or LK_NOWAIT and is only used if an unmount 230 * is in-progress. 231 * 232 * If no unmount is in-progress LK_NOWAIT is ignored. No other flag bits 233 * are used. A shared locked will be obtained and the filesystem will not 234 * be unmountable until the lock is released. 235 */ 236 int 237 vfs_busy(struct mount *mp, int flags) 238 { 239 int lkflags; 240 241 if (mp->mnt_kern_flag & MNTK_UNMOUNT) { 242 if (flags & LK_NOWAIT) 243 return (ENOENT); 244 /* XXX not MP safe */ 245 mp->mnt_kern_flag |= MNTK_MWAIT; 246 /* 247 * Since all busy locks are shared except the exclusive 248 * lock granted when unmounting, the only place that a 249 * wakeup needs to be done is at the release of the 250 * exclusive lock at the end of dounmount. 251 */ 252 tsleep((caddr_t)mp, 0, "vfs_busy", 0); 253 return (ENOENT); 254 } 255 lkflags = LK_SHARED; 256 if (lockmgr(&mp->mnt_lock, lkflags)) 257 panic("vfs_busy: unexpected lock failure"); 258 return (0); 259 } 260 261 /* 262 * Free a busy filesystem. 263 */ 264 void 265 vfs_unbusy(struct mount *mp) 266 { 267 lockmgr(&mp->mnt_lock, LK_RELEASE); 268 } 269 270 /* 271 * Lookup a filesystem type, and if found allocate and initialize 272 * a mount structure for it. 273 * 274 * Devname is usually updated by mount(8) after booting. 275 */ 276 int 277 vfs_rootmountalloc(char *fstypename, char *devname, struct mount **mpp) 278 { 279 struct vfsconf *vfsp; 280 struct mount *mp; 281 282 if (fstypename == NULL) 283 return (ENODEV); 284 for (vfsp = vfsconf; vfsp; vfsp = vfsp->vfc_next) { 285 if (!strcmp(vfsp->vfc_name, fstypename)) 286 break; 287 } 288 if (vfsp == NULL) 289 return (ENODEV); 290 mp = kmalloc(sizeof(struct mount), M_MOUNT, M_WAITOK | M_ZERO); 291 lockinit(&mp->mnt_lock, "vfslock", VLKTIMEOUT, 0); 292 vfs_busy(mp, LK_NOWAIT); 293 TAILQ_INIT(&mp->mnt_nvnodelist); 294 TAILQ_INIT(&mp->mnt_reservedvnlist); 295 TAILQ_INIT(&mp->mnt_jlist); 296 mp->mnt_nvnodelistsize = 0; 297 mp->mnt_vfc = vfsp; 298 mp->mnt_op = vfsp->vfc_vfsops; 299 mp->mnt_flag = MNT_RDONLY; 300 vfsp->vfc_refcount++; 301 mp->mnt_iosize_max = DFLTPHYS; 302 mp->mnt_stat.f_type = vfsp->vfc_typenum; 303 mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK; 304 strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN); 305 copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0); 306 *mpp = mp; 307 return (0); 308 } 309 310 /* 311 * Lookup a mount point by filesystem identifier. 312 */ 313 struct mount * 314 vfs_getvfs(fsid_t *fsid) 315 { 316 struct mount *mp; 317 lwkt_tokref ilock; 318 319 lwkt_gettoken(&ilock, &mountlist_token); 320 TAILQ_FOREACH(mp, &mountlist, mnt_list) { 321 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] && 322 mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) { 323 break; 324 } 325 } 326 lwkt_reltoken(&ilock); 327 return (mp); 328 } 329 330 /* 331 * Get a new unique fsid. Try to make its val[0] unique, since this value 332 * will be used to create fake device numbers for stat(). Also try (but 333 * not so hard) make its val[0] unique mod 2^16, since some emulators only 334 * support 16-bit device numbers. We end up with unique val[0]'s for the 335 * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls. 336 * 337 * Keep in mind that several mounts may be running in parallel. Starting 338 * the search one past where the previous search terminated is both a 339 * micro-optimization and a defense against returning the same fsid to 340 * different mounts. 341 */ 342 void 343 vfs_getnewfsid(struct mount *mp) 344 { 345 static u_int16_t mntid_base; 346 lwkt_tokref ilock; 347 fsid_t tfsid; 348 int mtype; 349 350 lwkt_gettoken(&ilock, &mntid_token); 351 mtype = mp->mnt_vfc->vfc_typenum; 352 tfsid.val[1] = mtype; 353 mtype = (mtype & 0xFF) << 24; 354 for (;;) { 355 tfsid.val[0] = makeudev(255, 356 mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF)); 357 mntid_base++; 358 if (vfs_getvfs(&tfsid) == NULL) 359 break; 360 } 361 mp->mnt_stat.f_fsid.val[0] = tfsid.val[0]; 362 mp->mnt_stat.f_fsid.val[1] = tfsid.val[1]; 363 lwkt_reltoken(&ilock); 364 } 365 366 /* 367 * Set the FSID for a new mount point to the template. Adjust 368 * the FSID to avoid collisions. 369 */ 370 int 371 vfs_setfsid(struct mount *mp, fsid_t *template) 372 { 373 int didmunge = 0; 374 375 bzero(&mp->mnt_stat.f_fsid, sizeof(mp->mnt_stat.f_fsid)); 376 for (;;) { 377 if (vfs_getvfs(template) == NULL) 378 break; 379 didmunge = 1; 380 ++template->val[1]; 381 } 382 mp->mnt_stat.f_fsid = *template; 383 return(didmunge); 384 } 385 386 /* 387 * This routine is called when we have too many vnodes. It attempts 388 * to free <count> vnodes and will potentially free vnodes that still 389 * have VM backing store (VM backing store is typically the cause 390 * of a vnode blowout so we want to do this). Therefore, this operation 391 * is not considered cheap. 392 * 393 * A number of conditions may prevent a vnode from being reclaimed. 394 * the buffer cache may have references on the vnode, a directory 395 * vnode may still have references due to the namei cache representing 396 * underlying files, or the vnode may be in active use. It is not 397 * desireable to reuse such vnodes. These conditions may cause the 398 * number of vnodes to reach some minimum value regardless of what 399 * you set kern.maxvnodes to. Do not set kern.maxvnodes too low. 400 */ 401 402 /* 403 * This is a quick non-blocking check to determine if the vnode is a good 404 * candidate for being (eventually) vgone()'d. Returns 0 if the vnode is 405 * not a good candidate, 1 if it is. 406 */ 407 static __inline int 408 vmightfree(struct vnode *vp, int page_count) 409 { 410 if (vp->v_flag & VRECLAIMED) 411 return (0); 412 #if 0 413 if ((vp->v_flag & VFREE) && TAILQ_EMPTY(&vp->v_namecache)) 414 return (0); 415 #endif 416 if (sysref_isactive(&vp->v_sysref)) 417 return (0); 418 if (vp->v_object && vp->v_object->resident_page_count >= page_count) 419 return (0); 420 return (1); 421 } 422 423 /* 424 * The vnode was found to be possibly vgone()able and the caller has locked it 425 * (thus the usecount should be 1 now). Determine if the vnode is actually 426 * vgone()able, doing some cleanups in the process. Returns 1 if the vnode 427 * can be vgone()'d, 0 otherwise. 428 * 429 * Note that v_auxrefs may be non-zero because (A) this vnode is not a leaf 430 * in the namecache topology and (B) this vnode has buffer cache bufs. 431 * We cannot remove vnodes with non-leaf namecache associations. We do a 432 * tentitive leaf check prior to attempting to flush out any buffers but the 433 * 'real' test when all is said in done is that v_auxrefs must become 0 for 434 * the vnode to be freeable. 435 * 436 * We could theoretically just unconditionally flush when v_auxrefs != 0, 437 * but flushing data associated with non-leaf nodes (which are always 438 * directories), just throws it away for no benefit. It is the buffer 439 * cache's responsibility to choose buffers to recycle from the cached 440 * data point of view. 441 */ 442 static int 443 visleaf(struct vnode *vp) 444 { 445 struct namecache *ncp; 446 447 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) { 448 if (!TAILQ_EMPTY(&ncp->nc_list)) 449 return(0); 450 } 451 return(1); 452 } 453 454 /* 455 * Try to clean up the vnode to the point where it can be vgone()'d, returning 456 * 0 if it cannot be vgone()'d (or already has been), 1 if it can. Unlike 457 * vmightfree() this routine may flush the vnode and block. Vnodes marked 458 * VFREE are still candidates for vgone()ing because they may hold namecache 459 * resources and could be blocking the namecache directory hierarchy (and 460 * related vnodes) from being freed. 461 */ 462 static int 463 vtrytomakegoneable(struct vnode *vp, int page_count) 464 { 465 if (vp->v_flag & VRECLAIMED) 466 return (0); 467 if (vp->v_sysref.refcnt > 1) 468 return (0); 469 if (vp->v_object && vp->v_object->resident_page_count >= page_count) 470 return (0); 471 if (vp->v_auxrefs && visleaf(vp)) { 472 vinvalbuf(vp, V_SAVE, 0, 0); 473 #if 0 /* DEBUG */ 474 kprintf((vp->v_auxrefs ? "vrecycle: vp %p failed: %s\n" : 475 "vrecycle: vp %p succeeded: %s\n"), vp, 476 (TAILQ_FIRST(&vp->v_namecache) ? 477 TAILQ_FIRST(&vp->v_namecache)->nc_name : "?")); 478 #endif 479 } 480 481 /* 482 * This sequence may seem a little strange, but we need to optimize 483 * the critical path a bit. We can't recycle vnodes with other 484 * references and because we are trying to recycle an otherwise 485 * perfectly fine vnode we have to invalidate the namecache in a 486 * way that avoids possible deadlocks (since the vnode lock is being 487 * held here). Finally, we have to check for other references one 488 * last time in case something snuck in during the inval. 489 */ 490 if (vp->v_sysref.refcnt > 1 || vp->v_auxrefs != 0) 491 return (0); 492 if (cache_inval_vp_nonblock(vp)) 493 return (0); 494 return (vp->v_sysref.refcnt <= 1 && vp->v_auxrefs == 0); 495 } 496 497 /* 498 * Reclaim up to 1/10 of the vnodes associated with a mount point. Try 499 * to avoid vnodes which have lots of resident pages (we are trying to free 500 * vnodes, not memory). 501 * 502 * This routine is a callback from the mountlist scan. The mount point 503 * in question will be busied. 504 */ 505 static int 506 vlrureclaim(struct mount *mp, void *data) 507 { 508 struct vnode *vp; 509 lwkt_tokref ilock; 510 int done; 511 int trigger; 512 int usevnodes; 513 int count; 514 int trigger_mult = vnlru_nowhere; 515 516 /* 517 * Calculate the trigger point for the resident pages check. The 518 * minimum trigger value is approximately the number of pages in 519 * the system divded by the number of vnodes. However, due to 520 * various other system memory overheads unrelated to data caching 521 * it is a good idea to double the trigger (at least). 522 * 523 * trigger_mult starts at 0. If the recycler is having problems 524 * finding enough freeable vnodes it will increase trigger_mult. 525 * This should not happen in normal operation, even on machines with 526 * low amounts of memory, but extraordinary memory use by the system 527 * verses the amount of cached data can trigger it. 528 */ 529 usevnodes = desiredvnodes; 530 if (usevnodes <= 0) 531 usevnodes = 1; 532 trigger = vmstats.v_page_count * (trigger_mult + 2) / usevnodes; 533 534 done = 0; 535 lwkt_gettoken(&ilock, &mntvnode_token); 536 count = mp->mnt_nvnodelistsize / 10 + 1; 537 while (count && mp->mnt_syncer) { 538 /* 539 * Next vnode. Use the special syncer vnode to placemark 540 * the LRU. This way the LRU code does not interfere with 541 * vmntvnodescan(). 542 */ 543 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes); 544 TAILQ_REMOVE(&mp->mnt_nvnodelist, mp->mnt_syncer, v_nmntvnodes); 545 if (vp) { 546 TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp, 547 mp->mnt_syncer, v_nmntvnodes); 548 } else { 549 TAILQ_INSERT_HEAD(&mp->mnt_nvnodelist, mp->mnt_syncer, 550 v_nmntvnodes); 551 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes); 552 if (vp == NULL) 553 break; 554 } 555 556 /* 557 * __VNODESCAN__ 558 * 559 * The VP will stick around while we hold mntvnode_token, 560 * at least until we block, so we can safely do an initial 561 * check, and then must check again after we lock the vnode. 562 */ 563 if (vp->v_type == VNON || /* syncer or indeterminant */ 564 !vmightfree(vp, trigger) /* critical path opt */ 565 ) { 566 --count; 567 continue; 568 } 569 570 /* 571 * VX get the candidate vnode. If the VX get fails the 572 * vnode might still be on the mountlist. Our loop depends 573 * on us at least cycling the vnode to the end of the 574 * mountlist. 575 */ 576 if (vx_get_nonblock(vp) != 0) { 577 --count; 578 continue; 579 } 580 581 /* 582 * Since we blocked locking the vp, make sure it is still 583 * a candidate for reclamation. That is, it has not already 584 * been reclaimed and only has our VX reference associated 585 * with it. 586 */ 587 if (vp->v_type == VNON || /* syncer or indeterminant */ 588 (vp->v_flag & VRECLAIMED) || 589 vp->v_mount != mp || 590 !vtrytomakegoneable(vp, trigger) /* critical path opt */ 591 ) { 592 --count; 593 vx_put(vp); 594 continue; 595 } 596 597 /* 598 * All right, we are good, move the vp to the end of the 599 * mountlist and clean it out. The vget will have returned 600 * an error if the vnode was destroyed (VRECLAIMED set), so we 601 * do not have to check again. The vput() will move the 602 * vnode to the free list if the vgone() was successful. 603 */ 604 KKASSERT(vp->v_mount == mp); 605 vgone_vxlocked(vp); 606 vx_put(vp); 607 ++done; 608 --count; 609 } 610 lwkt_reltoken(&ilock); 611 return (done); 612 } 613 614 /* 615 * Attempt to recycle vnodes in a context that is always safe to block. 616 * Calling vlrurecycle() from the bowels of file system code has some 617 * interesting deadlock problems. 618 */ 619 static struct thread *vnlruthread; 620 static int vnlruproc_sig; 621 622 void 623 vnlru_proc_wait(void) 624 { 625 if (vnlruproc_sig == 0) { 626 vnlruproc_sig = 1; /* avoid unnecessary wakeups */ 627 wakeup(vnlruthread); 628 } 629 tsleep(&vnlruproc_sig, 0, "vlruwk", hz); 630 } 631 632 static void 633 vnlru_proc(void) 634 { 635 struct thread *td = curthread; 636 int done; 637 638 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td, 639 SHUTDOWN_PRI_FIRST); 640 641 crit_enter(); 642 for (;;) { 643 kproc_suspend_loop(); 644 645 /* 646 * Try to free some vnodes if we have too many 647 */ 648 if (numvnodes > desiredvnodes && 649 freevnodes > desiredvnodes * 2 / 10) { 650 int count = numvnodes - desiredvnodes; 651 652 if (count > freevnodes / 100) 653 count = freevnodes / 100; 654 if (count < 5) 655 count = 5; 656 freesomevnodes(count); 657 } 658 659 /* 660 * Nothing to do if most of our vnodes are already on 661 * the free list. 662 */ 663 if (numvnodes - freevnodes <= desiredvnodes * 9 / 10) { 664 vnlruproc_sig = 0; 665 wakeup(&vnlruproc_sig); 666 tsleep(td, 0, "vlruwt", hz); 667 continue; 668 } 669 cache_cleanneg(0); 670 done = mountlist_scan(vlrureclaim, NULL, MNTSCAN_FORWARD); 671 672 /* 673 * The vlrureclaim() call only processes 1/10 of the vnodes 674 * on each mount. If we couldn't find any repeat the loop 675 * at least enough times to cover all available vnodes before 676 * we start sleeping. Complain if the failure extends past 677 * 30 second, every 30 seconds. 678 */ 679 if (done == 0) { 680 ++vnlru_nowhere; 681 if (vnlru_nowhere % 10 == 0) 682 tsleep(td, 0, "vlrup", hz * 3); 683 if (vnlru_nowhere % 100 == 0) 684 kprintf("vnlru_proc: vnode recycler stopped working!\n"); 685 if (vnlru_nowhere == 1000) 686 vnlru_nowhere = 900; 687 } else { 688 vnlru_nowhere = 0; 689 } 690 } 691 crit_exit(); 692 } 693 694 /* 695 * MOUNTLIST FUNCTIONS 696 */ 697 698 /* 699 * mountlist_insert (MP SAFE) 700 * 701 * Add a new mount point to the mount list. 702 */ 703 void 704 mountlist_insert(struct mount *mp, int how) 705 { 706 lwkt_tokref ilock; 707 708 lwkt_gettoken(&ilock, &mountlist_token); 709 if (how == MNTINS_FIRST) 710 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list); 711 else 712 TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list); 713 lwkt_reltoken(&ilock); 714 } 715 716 /* 717 * mountlist_interlock (MP SAFE) 718 * 719 * Execute the specified interlock function with the mountlist token 720 * held. The function will be called in a serialized fashion verses 721 * other functions called through this mechanism. 722 */ 723 int 724 mountlist_interlock(int (*callback)(struct mount *), struct mount *mp) 725 { 726 lwkt_tokref ilock; 727 int error; 728 729 lwkt_gettoken(&ilock, &mountlist_token); 730 error = callback(mp); 731 lwkt_reltoken(&ilock); 732 return (error); 733 } 734 735 /* 736 * mountlist_boot_getfirst (DURING BOOT ONLY) 737 * 738 * This function returns the first mount on the mountlist, which is 739 * expected to be the root mount. Since no interlocks are obtained 740 * this function is only safe to use during booting. 741 */ 742 743 struct mount * 744 mountlist_boot_getfirst(void) 745 { 746 return(TAILQ_FIRST(&mountlist)); 747 } 748 749 /* 750 * mountlist_remove (MP SAFE) 751 * 752 * Remove a node from the mountlist. If this node is the next scan node 753 * for any active mountlist scans, the active mountlist scan will be 754 * adjusted to skip the node, thus allowing removals during mountlist 755 * scans. 756 */ 757 void 758 mountlist_remove(struct mount *mp) 759 { 760 struct mountscan_info *msi; 761 lwkt_tokref ilock; 762 763 lwkt_gettoken(&ilock, &mountlist_token); 764 TAILQ_FOREACH(msi, &mountscan_list, msi_entry) { 765 if (msi->msi_node == mp) { 766 if (msi->msi_how & MNTSCAN_FORWARD) 767 msi->msi_node = TAILQ_NEXT(mp, mnt_list); 768 else 769 msi->msi_node = TAILQ_PREV(mp, mntlist, mnt_list); 770 } 771 } 772 TAILQ_REMOVE(&mountlist, mp, mnt_list); 773 lwkt_reltoken(&ilock); 774 } 775 776 /* 777 * mountlist_scan (MP SAFE) 778 * 779 * Safely scan the mount points on the mount list. Unless otherwise 780 * specified each mount point will be busied prior to the callback and 781 * unbusied afterwords. The callback may safely remove any mount point 782 * without interfering with the scan. If the current callback 783 * mount is removed the scanner will not attempt to unbusy it. 784 * 785 * If a mount node cannot be busied it is silently skipped. 786 * 787 * The callback return value is aggregated and a total is returned. A return 788 * value of < 0 is not aggregated and will terminate the scan. 789 * 790 * MNTSCAN_FORWARD - the mountlist is scanned in the forward direction 791 * MNTSCAN_REVERSE - the mountlist is scanned in reverse 792 * MNTSCAN_NOBUSY - the scanner will make the callback without busying 793 * the mount node. 794 */ 795 int 796 mountlist_scan(int (*callback)(struct mount *, void *), void *data, int how) 797 { 798 struct mountscan_info info; 799 lwkt_tokref ilock; 800 struct mount *mp; 801 thread_t td; 802 int count; 803 int res; 804 805 lwkt_gettoken(&ilock, &mountlist_token); 806 807 info.msi_how = how; 808 info.msi_node = NULL; /* paranoia */ 809 TAILQ_INSERT_TAIL(&mountscan_list, &info, msi_entry); 810 811 res = 0; 812 td = curthread; 813 814 if (how & MNTSCAN_FORWARD) { 815 info.msi_node = TAILQ_FIRST(&mountlist); 816 while ((mp = info.msi_node) != NULL) { 817 if (how & MNTSCAN_NOBUSY) { 818 count = callback(mp, data); 819 } else if (vfs_busy(mp, LK_NOWAIT) == 0) { 820 count = callback(mp, data); 821 if (mp == info.msi_node) 822 vfs_unbusy(mp); 823 } else { 824 count = 0; 825 } 826 if (count < 0) 827 break; 828 res += count; 829 if (mp == info.msi_node) 830 info.msi_node = TAILQ_NEXT(mp, mnt_list); 831 } 832 } else if (how & MNTSCAN_REVERSE) { 833 info.msi_node = TAILQ_LAST(&mountlist, mntlist); 834 while ((mp = info.msi_node) != NULL) { 835 if (how & MNTSCAN_NOBUSY) { 836 count = callback(mp, data); 837 } else if (vfs_busy(mp, LK_NOWAIT) == 0) { 838 count = callback(mp, data); 839 if (mp == info.msi_node) 840 vfs_unbusy(mp); 841 } else { 842 count = 0; 843 } 844 if (count < 0) 845 break; 846 res += count; 847 if (mp == info.msi_node) 848 info.msi_node = TAILQ_PREV(mp, mntlist, mnt_list); 849 } 850 } 851 TAILQ_REMOVE(&mountscan_list, &info, msi_entry); 852 lwkt_reltoken(&ilock); 853 return(res); 854 } 855 856 /* 857 * MOUNT RELATED VNODE FUNCTIONS 858 */ 859 860 static struct kproc_desc vnlru_kp = { 861 "vnlru", 862 vnlru_proc, 863 &vnlruthread 864 }; 865 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp) 866 867 /* 868 * Move a vnode from one mount queue to another. 869 */ 870 void 871 insmntque(struct vnode *vp, struct mount *mp) 872 { 873 lwkt_tokref ilock; 874 875 lwkt_gettoken(&ilock, &mntvnode_token); 876 /* 877 * Delete from old mount point vnode list, if on one. 878 */ 879 if (vp->v_mount != NULL) { 880 KASSERT(vp->v_mount->mnt_nvnodelistsize > 0, 881 ("bad mount point vnode list size")); 882 vremovevnodemnt(vp); 883 vp->v_mount->mnt_nvnodelistsize--; 884 } 885 /* 886 * Insert into list of vnodes for the new mount point, if available. 887 * The 'end' of the LRU list is the vnode prior to mp->mnt_syncer. 888 */ 889 if ((vp->v_mount = mp) == NULL) { 890 lwkt_reltoken(&ilock); 891 return; 892 } 893 if (mp->mnt_syncer) { 894 TAILQ_INSERT_BEFORE(mp->mnt_syncer, vp, v_nmntvnodes); 895 } else { 896 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes); 897 } 898 mp->mnt_nvnodelistsize++; 899 lwkt_reltoken(&ilock); 900 } 901 902 903 /* 904 * Scan the vnodes under a mount point and issue appropriate callbacks. 905 * 906 * The fastfunc() callback is called with just the mountlist token held 907 * (no vnode lock). It may not block and the vnode may be undergoing 908 * modifications while the caller is processing it. The vnode will 909 * not be entirely destroyed, however, due to the fact that the mountlist 910 * token is held. A return value < 0 skips to the next vnode without calling 911 * the slowfunc(), a return value > 0 terminates the loop. 912 * 913 * The slowfunc() callback is called after the vnode has been successfully 914 * locked based on passed flags. The vnode is skipped if it gets rearranged 915 * or destroyed while blocking on the lock. A non-zero return value from 916 * the slow function terminates the loop. The slow function is allowed to 917 * arbitrarily block. The scanning code guarentees consistency of operation 918 * even if the slow function deletes or moves the node, or blocks and some 919 * other thread deletes or moves the node. 920 */ 921 int 922 vmntvnodescan( 923 struct mount *mp, 924 int flags, 925 int (*fastfunc)(struct mount *mp, struct vnode *vp, void *data), 926 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data), 927 void *data 928 ) { 929 struct vmntvnodescan_info info; 930 lwkt_tokref ilock; 931 struct vnode *vp; 932 int r = 0; 933 int maxcount = 1000000; 934 int stopcount = 0; 935 int count = 0; 936 937 lwkt_gettoken(&ilock, &mntvnode_token); 938 939 /* 940 * If asked to do one pass stop after iterating available vnodes. 941 * Under heavy loads new vnodes can be added while we are scanning, 942 * so this isn't perfect. Create a slop factor of 2x. 943 */ 944 if (flags & VMSC_ONEPASS) 945 stopcount = mp->mnt_nvnodelistsize * 2; 946 947 info.vp = TAILQ_FIRST(&mp->mnt_nvnodelist); 948 TAILQ_INSERT_TAIL(&mntvnodescan_list, &info, entry); 949 while ((vp = info.vp) != NULL) { 950 if (--maxcount == 0) 951 panic("maxcount reached during vmntvnodescan"); 952 953 /* 954 * Skip if visible but not ready, or special (e.g. 955 * mp->mnt_syncer) 956 */ 957 if (vp->v_type == VNON) 958 goto next; 959 KKASSERT(vp->v_mount == mp); 960 961 /* 962 * Quick test. A negative return continues the loop without 963 * calling the slow test. 0 continues onto the slow test. 964 * A positive number aborts the loop. 965 */ 966 if (fastfunc) { 967 if ((r = fastfunc(mp, vp, data)) < 0) { 968 r = 0; 969 goto next; 970 } 971 if (r) 972 break; 973 } 974 975 /* 976 * Get a vxlock on the vnode, retry if it has moved or isn't 977 * in the mountlist where we expect it. 978 */ 979 if (slowfunc) { 980 int error; 981 982 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) { 983 case VMSC_GETVP: 984 error = vget(vp, LK_EXCLUSIVE); 985 break; 986 case VMSC_GETVP|VMSC_NOWAIT: 987 error = vget(vp, LK_EXCLUSIVE|LK_NOWAIT); 988 break; 989 case VMSC_GETVX: 990 vx_get(vp); 991 error = 0; 992 break; 993 default: 994 error = 0; 995 break; 996 } 997 if (error) 998 goto next; 999 /* 1000 * Do not call the slow function if the vnode is 1001 * invalid or if it was ripped out from under us 1002 * while we (potentially) blocked. 1003 */ 1004 if (info.vp == vp && vp->v_type != VNON) 1005 r = slowfunc(mp, vp, data); 1006 1007 /* 1008 * Cleanup 1009 */ 1010 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) { 1011 case VMSC_GETVP: 1012 case VMSC_GETVP|VMSC_NOWAIT: 1013 vput(vp); 1014 break; 1015 case VMSC_GETVX: 1016 vx_put(vp); 1017 break; 1018 default: 1019 break; 1020 } 1021 if (r != 0) 1022 break; 1023 } 1024 1025 next: 1026 /* 1027 * Yield after some processing. Depending on the number 1028 * of vnodes, we might wind up running for a long time. 1029 * Because threads are not preemptable, time critical 1030 * userland processes might starve. Give them a chance 1031 * now and then. 1032 */ 1033 if (++count == 10000) { 1034 /* We really want to yield a bit, so we simply sleep a tick */ 1035 tsleep(mp, 0, "vnodescn", 1); 1036 count = 0; 1037 } 1038 1039 /* 1040 * If doing one pass this decrements to zero. If it starts 1041 * at zero it is effectively unlimited for the purposes of 1042 * this loop. 1043 */ 1044 if (--stopcount == 0) 1045 break; 1046 1047 /* 1048 * Iterate. If the vnode was ripped out from under us 1049 * info.vp will already point to the next vnode, otherwise 1050 * we have to obtain the next valid vnode ourselves. 1051 */ 1052 if (info.vp == vp) 1053 info.vp = TAILQ_NEXT(vp, v_nmntvnodes); 1054 } 1055 TAILQ_REMOVE(&mntvnodescan_list, &info, entry); 1056 lwkt_reltoken(&ilock); 1057 return(r); 1058 } 1059 1060 /* 1061 * Remove any vnodes in the vnode table belonging to mount point mp. 1062 * 1063 * If FORCECLOSE is not specified, there should not be any active ones, 1064 * return error if any are found (nb: this is a user error, not a 1065 * system error). If FORCECLOSE is specified, detach any active vnodes 1066 * that are found. 1067 * 1068 * If WRITECLOSE is set, only flush out regular file vnodes open for 1069 * writing. 1070 * 1071 * SKIPSYSTEM causes any vnodes marked VSYSTEM to be skipped. 1072 * 1073 * `rootrefs' specifies the base reference count for the root vnode 1074 * of this filesystem. The root vnode is considered busy if its 1075 * v_sysref.refcnt exceeds this value. On a successful return, vflush() 1076 * will call vrele() on the root vnode exactly rootrefs times. 1077 * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must 1078 * be zero. 1079 */ 1080 #ifdef DIAGNOSTIC 1081 static int busyprt = 0; /* print out busy vnodes */ 1082 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, ""); 1083 #endif 1084 1085 static int vflush_scan(struct mount *mp, struct vnode *vp, void *data); 1086 1087 struct vflush_info { 1088 int flags; 1089 int busy; 1090 thread_t td; 1091 }; 1092 1093 int 1094 vflush(struct mount *mp, int rootrefs, int flags) 1095 { 1096 struct thread *td = curthread; /* XXX */ 1097 struct vnode *rootvp = NULL; 1098 int error; 1099 struct vflush_info vflush_info; 1100 1101 if (rootrefs > 0) { 1102 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0, 1103 ("vflush: bad args")); 1104 /* 1105 * Get the filesystem root vnode. We can vput() it 1106 * immediately, since with rootrefs > 0, it won't go away. 1107 */ 1108 if ((error = VFS_ROOT(mp, &rootvp)) != 0) 1109 return (error); 1110 vput(rootvp); 1111 } 1112 1113 vflush_info.busy = 0; 1114 vflush_info.flags = flags; 1115 vflush_info.td = td; 1116 vmntvnodescan(mp, VMSC_GETVX, NULL, vflush_scan, &vflush_info); 1117 1118 if (rootrefs > 0 && (flags & FORCECLOSE) == 0) { 1119 /* 1120 * If just the root vnode is busy, and if its refcount 1121 * is equal to `rootrefs', then go ahead and kill it. 1122 */ 1123 KASSERT(vflush_info.busy > 0, ("vflush: not busy")); 1124 KASSERT(rootvp->v_sysref.refcnt >= rootrefs, ("vflush: rootrefs")); 1125 if (vflush_info.busy == 1 && rootvp->v_sysref.refcnt == rootrefs) { 1126 vx_lock(rootvp); 1127 vgone_vxlocked(rootvp); 1128 vx_unlock(rootvp); 1129 vflush_info.busy = 0; 1130 } 1131 } 1132 if (vflush_info.busy) 1133 return (EBUSY); 1134 for (; rootrefs > 0; rootrefs--) 1135 vrele(rootvp); 1136 return (0); 1137 } 1138 1139 /* 1140 * The scan callback is made with an VX locked vnode. 1141 */ 1142 static int 1143 vflush_scan(struct mount *mp, struct vnode *vp, void *data) 1144 { 1145 struct vflush_info *info = data; 1146 struct vattr vattr; 1147 1148 /* 1149 * Skip over a vnodes marked VSYSTEM. 1150 */ 1151 if ((info->flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) { 1152 return(0); 1153 } 1154 1155 /* 1156 * If WRITECLOSE is set, flush out unlinked but still open 1157 * files (even if open only for reading) and regular file 1158 * vnodes open for writing. 1159 */ 1160 if ((info->flags & WRITECLOSE) && 1161 (vp->v_type == VNON || 1162 (VOP_GETATTR(vp, &vattr) == 0 && 1163 vattr.va_nlink > 0)) && 1164 (vp->v_writecount == 0 || vp->v_type != VREG)) { 1165 return(0); 1166 } 1167 1168 /* 1169 * If we are the only holder (refcnt of 1) or the vnode is in 1170 * termination (refcnt < 0), we can vgone the vnode. 1171 */ 1172 if (vp->v_sysref.refcnt <= 1) { 1173 vgone_vxlocked(vp); 1174 return(0); 1175 } 1176 1177 /* 1178 * If FORCECLOSE is set, forcibly close the vnode. For block 1179 * or character devices, revert to an anonymous device. For 1180 * all other files, just kill them. 1181 */ 1182 if (info->flags & FORCECLOSE) { 1183 if (vp->v_type != VBLK && vp->v_type != VCHR) { 1184 vgone_vxlocked(vp); 1185 } else { 1186 vclean_vxlocked(vp, 0); 1187 vp->v_ops = &spec_vnode_vops_p; 1188 insmntque(vp, NULL); 1189 } 1190 return(0); 1191 } 1192 #ifdef DIAGNOSTIC 1193 if (busyprt) 1194 vprint("vflush: busy vnode", vp); 1195 #endif 1196 ++info->busy; 1197 return(0); 1198 } 1199 1200 void 1201 add_bio_ops(struct bio_ops *ops) 1202 { 1203 TAILQ_INSERT_TAIL(&bio_ops_list, ops, entry); 1204 } 1205 1206 void 1207 rem_bio_ops(struct bio_ops *ops) 1208 { 1209 TAILQ_REMOVE(&bio_ops_list, ops, entry); 1210 } 1211 1212 /* 1213 * This calls the bio_ops io_sync function either for a mount point 1214 * or generally. 1215 * 1216 * WARNING: softdeps is weirdly coded and just isn't happy unless 1217 * io_sync is called with a NULL mount from the general syncing code. 1218 */ 1219 void 1220 bio_ops_sync(struct mount *mp) 1221 { 1222 struct bio_ops *ops; 1223 1224 if (mp) { 1225 if ((ops = mp->mnt_bioops) != NULL) 1226 ops->io_sync(mp); 1227 } else { 1228 TAILQ_FOREACH(ops, &bio_ops_list, entry) { 1229 ops->io_sync(NULL); 1230 } 1231 } 1232 } 1233 1234