1 /* 2 * Copyright (c) 2004,2013 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. Neither the name of the University nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 64 * SUCH DAMAGE. 65 */ 66 67 /* 68 * External virtual filesystem routines 69 */ 70 71 #include <sys/param.h> 72 #include <sys/systm.h> 73 #include <sys/kernel.h> 74 #include <sys/malloc.h> 75 #include <sys/mount.h> 76 #include <sys/proc.h> 77 #include <sys/vnode.h> 78 #include <sys/buf.h> 79 #include <sys/eventhandler.h> 80 #include <sys/kthread.h> 81 #include <sys/sysctl.h> 82 83 #include <machine/limits.h> 84 85 #include <sys/buf2.h> 86 87 #include <vm/vm.h> 88 #include <vm/vm_object.h> 89 90 struct mountscan_info { 91 TAILQ_ENTRY(mountscan_info) msi_entry; 92 int msi_how; 93 struct mount *msi_node; 94 }; 95 96 struct vmntvnodescan_info { 97 TAILQ_ENTRY(vmntvnodescan_info) entry; 98 struct vnode *vp; 99 }; 100 101 struct vnlru_info { 102 int pass; 103 }; 104 105 static int vnlru_nowhere = 0; 106 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RD, 107 &vnlru_nowhere, 0, 108 "Number of times the vnlru process ran without success"); 109 110 111 static struct lwkt_token mntid_token; 112 static struct mount dummymount; 113 114 /* note: mountlist exported to pstat */ 115 struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist); 116 static TAILQ_HEAD(,mountscan_info) mountscan_list; 117 static struct lwkt_token mountlist_token; 118 119 static TAILQ_HEAD(,bio_ops) bio_ops_list = TAILQ_HEAD_INITIALIZER(bio_ops_list); 120 121 /* 122 * Called from vfsinit() 123 */ 124 void 125 vfs_mount_init(void) 126 { 127 lwkt_token_init(&mountlist_token, "mntlist"); 128 lwkt_token_init(&mntid_token, "mntid"); 129 TAILQ_INIT(&mountscan_list); 130 mount_init(&dummymount); 131 dummymount.mnt_flag |= MNT_RDONLY; 132 dummymount.mnt_kern_flag |= MNTK_ALL_MPSAFE; 133 } 134 135 /* 136 * Support function called to remove a vnode from the mountlist and 137 * deal with side effects for scans in progress. 138 * 139 * Target mnt_token is held on call. 140 */ 141 static void 142 vremovevnodemnt(struct vnode *vp) 143 { 144 struct vmntvnodescan_info *info; 145 struct mount *mp = vp->v_mount; 146 147 TAILQ_FOREACH(info, &mp->mnt_vnodescan_list, entry) { 148 if (info->vp == vp) 149 info->vp = TAILQ_NEXT(vp, v_nmntvnodes); 150 } 151 TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes); 152 } 153 154 /* 155 * Allocate a new vnode and associate it with a tag, mount point, and 156 * operations vector. 157 * 158 * A VX locked and refd vnode is returned. The caller should setup the 159 * remaining fields and vx_put() or, if he wishes to leave a vref, 160 * vx_unlock() the vnode. 161 */ 162 int 163 getnewvnode(enum vtagtype tag, struct mount *mp, 164 struct vnode **vpp, int lktimeout, int lkflags) 165 { 166 struct vnode *vp; 167 168 KKASSERT(mp != NULL); 169 170 vp = allocvnode(lktimeout, lkflags); 171 vp->v_tag = tag; 172 vp->v_data = NULL; 173 174 /* 175 * By default the vnode is assigned the mount point's normal 176 * operations vector. 177 */ 178 vp->v_ops = &mp->mnt_vn_use_ops; 179 vp->v_pbuf_count = nswbuf_kva / NSWBUF_SPLIT; 180 181 /* 182 * Placing the vnode on the mount point's queue makes it visible. 183 * VNON prevents it from being messed with, however. 184 */ 185 insmntque(vp, mp); 186 187 /* 188 * A VX locked & refd vnode is returned. 189 */ 190 *vpp = vp; 191 return (0); 192 } 193 194 /* 195 * This function creates vnodes with special operations vectors. The 196 * mount point is optional. 197 * 198 * This routine is being phased out but is still used by vfs_conf to 199 * create vnodes for devices prior to the root mount (with mp == NULL). 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 if (mp == NULL) 214 mp = &dummymount; 215 216 /* 217 * Placing the vnode on the mount point's queue makes it visible. 218 * VNON prevents it from being messed with, however. 219 */ 220 insmntque(vp, mp); 221 222 /* 223 * A VX locked & refd vnode is returned. 224 */ 225 *vpp = vp; 226 return (0); 227 } 228 229 /* 230 * Interlock against an unmount, return 0 on success, non-zero on failure. 231 * 232 * The passed flag may be 0 or LK_NOWAIT and is only used if an unmount 233 * is in-progress. 234 * 235 * If no unmount is in-progress LK_NOWAIT is ignored. No other flag bits 236 * are used. A shared locked will be obtained and the filesystem will not 237 * be unmountable until the lock is released. 238 */ 239 int 240 vfs_busy(struct mount *mp, int flags) 241 { 242 int lkflags; 243 244 atomic_add_int(&mp->mnt_refs, 1); 245 lwkt_gettoken(&mp->mnt_token); 246 if (mp->mnt_kern_flag & MNTK_UNMOUNT) { 247 if (flags & LK_NOWAIT) { 248 lwkt_reltoken(&mp->mnt_token); 249 atomic_add_int(&mp->mnt_refs, -1); 250 return (ENOENT); 251 } 252 /* XXX not MP safe */ 253 mp->mnt_kern_flag |= MNTK_MWAIT; 254 255 /* 256 * Since all busy locks are shared except the exclusive 257 * lock granted when unmounting, the only place that a 258 * wakeup needs to be done is at the release of the 259 * exclusive lock at the end of dounmount. 260 * 261 * WARNING! mp can potentially go away once we release 262 * our ref. 263 */ 264 tsleep((caddr_t)mp, 0, "vfs_busy", 0); 265 lwkt_reltoken(&mp->mnt_token); 266 atomic_add_int(&mp->mnt_refs, -1); 267 return (ENOENT); 268 } 269 lkflags = LK_SHARED; 270 if (lockmgr(&mp->mnt_lock, lkflags)) 271 panic("vfs_busy: unexpected lock failure"); 272 lwkt_reltoken(&mp->mnt_token); 273 return (0); 274 } 275 276 /* 277 * Free a busy filesystem. 278 * 279 * Once refs is decremented the mount point can potentially get ripped 280 * out from under us, but we want to clean up our refs before unlocking 281 * so do a hold/drop around the whole mess. 282 * 283 * This is not in the critical path (I hope). 284 */ 285 void 286 vfs_unbusy(struct mount *mp) 287 { 288 mount_hold(mp); 289 atomic_add_int(&mp->mnt_refs, -1); 290 lockmgr(&mp->mnt_lock, LK_RELEASE); 291 mount_drop(mp); 292 } 293 294 /* 295 * Lookup a filesystem type, and if found allocate and initialize 296 * a mount structure for it. 297 * 298 * Devname is usually updated by mount(8) after booting. 299 */ 300 int 301 vfs_rootmountalloc(char *fstypename, char *devname, struct mount **mpp) 302 { 303 struct vfsconf *vfsp; 304 struct mount *mp; 305 306 if (fstypename == NULL) 307 return (ENODEV); 308 309 vfsp = vfsconf_find_by_name(fstypename); 310 if (vfsp == NULL) 311 return (ENODEV); 312 mp = kmalloc(sizeof(struct mount), M_MOUNT, M_WAITOK | M_ZERO); 313 mount_init(mp); 314 lockinit(&mp->mnt_lock, "vfslock", VLKTIMEOUT, 0); 315 316 vfs_busy(mp, 0); 317 mp->mnt_vfc = vfsp; 318 mp->mnt_op = vfsp->vfc_vfsops; 319 mp->mnt_pbuf_count = nswbuf_kva / NSWBUF_SPLIT; 320 vfsp->vfc_refcount++; 321 mp->mnt_stat.f_type = vfsp->vfc_typenum; 322 mp->mnt_flag |= MNT_RDONLY; 323 mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK; 324 strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN); 325 copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0); 326 327 /* 328 * Pre-set MPSAFE flags for VFS_MOUNT() call. 329 */ 330 if (vfsp->vfc_flags & VFCF_MPSAFE) 331 mp->mnt_kern_flag |= MNTK_ALL_MPSAFE; 332 333 *mpp = mp; 334 335 return (0); 336 } 337 338 /* 339 * Basic mount structure initialization 340 */ 341 void 342 mount_init(struct mount *mp) 343 { 344 lockinit(&mp->mnt_lock, "vfslock", hz*5, 0); 345 lwkt_token_init(&mp->mnt_token, "permnt"); 346 347 TAILQ_INIT(&mp->mnt_vnodescan_list); 348 TAILQ_INIT(&mp->mnt_nvnodelist); 349 TAILQ_INIT(&mp->mnt_reservedvnlist); 350 TAILQ_INIT(&mp->mnt_jlist); 351 mp->mnt_nvnodelistsize = 0; 352 mp->mnt_flag = 0; 353 mp->mnt_hold = 1; /* hold for umount last drop */ 354 mp->mnt_iosize_max = MAXPHYS; 355 vn_syncer_thr_create(mp); 356 } 357 358 void 359 mount_hold(struct mount *mp) 360 { 361 atomic_add_int(&mp->mnt_hold, 1); 362 } 363 364 void 365 mount_drop(struct mount *mp) 366 { 367 if (atomic_fetchadd_int(&mp->mnt_hold, -1) == 1) { 368 KKASSERT(mp->mnt_refs == 0); 369 kfree(mp, M_MOUNT); 370 } 371 } 372 373 /* 374 * Lookup a mount point by filesystem identifier. 375 * 376 * If not NULL, the returned mp is held and the caller is expected to drop 377 * it via mount_drop(). 378 */ 379 struct mount * 380 vfs_getvfs(fsid_t *fsid) 381 { 382 struct mount *mp; 383 384 lwkt_gettoken_shared(&mountlist_token); 385 TAILQ_FOREACH(mp, &mountlist, mnt_list) { 386 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] && 387 mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) { 388 mount_hold(mp); 389 break; 390 } 391 } 392 lwkt_reltoken(&mountlist_token); 393 return (mp); 394 } 395 396 /* 397 * Get a new unique fsid. Try to make its val[0] unique, since this value 398 * will be used to create fake device numbers for stat(). Also try (but 399 * not so hard) make its val[0] unique mod 2^16, since some emulators only 400 * support 16-bit device numbers. We end up with unique val[0]'s for the 401 * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls. 402 * 403 * Keep in mind that several mounts may be running in parallel. Starting 404 * the search one past where the previous search terminated is both a 405 * micro-optimization and a defense against returning the same fsid to 406 * different mounts. 407 */ 408 void 409 vfs_getnewfsid(struct mount *mp) 410 { 411 static u_int16_t mntid_base; 412 struct mount *mptmp; 413 fsid_t tfsid; 414 int mtype; 415 416 lwkt_gettoken(&mntid_token); 417 mtype = mp->mnt_vfc->vfc_typenum; 418 tfsid.val[1] = mtype; 419 mtype = (mtype & 0xFF) << 24; 420 for (;;) { 421 tfsid.val[0] = makeudev(255, 422 mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF)); 423 mntid_base++; 424 mptmp = vfs_getvfs(&tfsid); 425 if (mptmp == NULL) 426 break; 427 mount_drop(mptmp); 428 } 429 mp->mnt_stat.f_fsid.val[0] = tfsid.val[0]; 430 mp->mnt_stat.f_fsid.val[1] = tfsid.val[1]; 431 lwkt_reltoken(&mntid_token); 432 } 433 434 /* 435 * Set the FSID for a new mount point to the template. Adjust 436 * the FSID to avoid collisions. 437 */ 438 int 439 vfs_setfsid(struct mount *mp, fsid_t *template) 440 { 441 struct mount *mptmp; 442 int didmunge = 0; 443 444 bzero(&mp->mnt_stat.f_fsid, sizeof(mp->mnt_stat.f_fsid)); 445 446 lwkt_gettoken(&mntid_token); 447 for (;;) { 448 mptmp = vfs_getvfs(template); 449 if (mptmp == NULL) 450 break; 451 mount_drop(mptmp); 452 didmunge = 1; 453 ++template->val[1]; 454 } 455 mp->mnt_stat.f_fsid = *template; 456 lwkt_reltoken(&mntid_token); 457 458 return(didmunge); 459 } 460 461 /* 462 * This routine is called when we have too many vnodes. It attempts 463 * to free <count> vnodes and will potentially free vnodes that still 464 * have VM backing store (VM backing store is typically the cause 465 * of a vnode blowout so we want to do this). Therefore, this operation 466 * is not considered cheap. 467 * 468 * A number of conditions may prevent a vnode from being reclaimed. 469 * the buffer cache may have references on the vnode, a directory 470 * vnode may still have references due to the namei cache representing 471 * underlying files, or the vnode may be in active use. It is not 472 * desireable to reuse such vnodes. These conditions may cause the 473 * number of vnodes to reach some minimum value regardless of what 474 * you set kern.maxvnodes to. Do not set kern.maxvnodes too low. 475 */ 476 477 /* 478 * Attempt to recycle vnodes in a context that is always safe to block. 479 * Calling vlrurecycle() from the bowels of file system code has some 480 * interesting deadlock problems. 481 */ 482 static struct thread *vnlruthread; 483 484 static void 485 vnlru_proc(void) 486 { 487 struct thread *td = curthread; 488 489 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td, 490 SHUTDOWN_PRI_FIRST); 491 492 for (;;) { 493 int ncachedandinactive; 494 495 kproc_suspend_loop(); 496 497 /* 498 * Try to free some vnodes if we have too many. Trigger based 499 * on potentially freeable vnodes but calculate the count 500 * based on total vnodes. 501 * 502 * (long) -> deal with 64 bit machines, intermediate overflow 503 */ 504 synchronizevnodecount(); 505 ncachedandinactive = countcachedandinactivevnodes(); 506 if (numvnodes >= maxvnodes * 9 / 10 && 507 ncachedandinactive >= maxvnodes * 5 / 10) { 508 int count = numvnodes - maxvnodes * 9 / 10; 509 510 if (count > (ncachedandinactive) / 100) 511 count = (ncachedandinactive) / 100; 512 if (count < 5) 513 count = 5; 514 freesomevnodes(count); 515 } 516 517 /* 518 * Do non-critical-path (more robust) cache cleaning, 519 * even if vnode counts are nominal, to try to avoid 520 * having to do it in the critical path. 521 */ 522 cache_hysteresis(0); 523 524 /* 525 * Nothing to do if most of our vnodes are already on 526 * the free list. 527 */ 528 synchronizevnodecount(); 529 ncachedandinactive = countcachedandinactivevnodes(); 530 if (numvnodes <= maxvnodes * 9 / 10 || 531 ncachedandinactive <= maxvnodes * 5 / 10) { 532 tsleep(vnlruthread, 0, "vlruwt", hz); 533 continue; 534 } 535 } 536 } 537 538 /* 539 * MOUNTLIST FUNCTIONS 540 */ 541 542 /* 543 * mountlist_insert (MP SAFE) 544 * 545 * Add a new mount point to the mount list. 546 */ 547 void 548 mountlist_insert(struct mount *mp, int how) 549 { 550 lwkt_gettoken(&mountlist_token); 551 if (how == MNTINS_FIRST) 552 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list); 553 else 554 TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list); 555 lwkt_reltoken(&mountlist_token); 556 } 557 558 /* 559 * mountlist_interlock (MP SAFE) 560 * 561 * Execute the specified interlock function with the mountlist token 562 * held. The function will be called in a serialized fashion verses 563 * other functions called through this mechanism. 564 * 565 * The function is expected to be very short-lived. 566 */ 567 int 568 mountlist_interlock(int (*callback)(struct mount *), struct mount *mp) 569 { 570 int error; 571 572 lwkt_gettoken(&mountlist_token); 573 error = callback(mp); 574 lwkt_reltoken(&mountlist_token); 575 return (error); 576 } 577 578 /* 579 * mountlist_boot_getfirst (DURING BOOT ONLY) 580 * 581 * This function returns the first mount on the mountlist, which is 582 * expected to be the root mount. Since no interlocks are obtained 583 * this function is only safe to use during booting. 584 */ 585 586 struct mount * 587 mountlist_boot_getfirst(void) 588 { 589 return(TAILQ_FIRST(&mountlist)); 590 } 591 592 /* 593 * mountlist_remove (MP SAFE) 594 * 595 * Remove a node from the mountlist. If this node is the next scan node 596 * for any active mountlist scans, the active mountlist scan will be 597 * adjusted to skip the node, thus allowing removals during mountlist 598 * scans. 599 */ 600 void 601 mountlist_remove(struct mount *mp) 602 { 603 struct mountscan_info *msi; 604 605 lwkt_gettoken(&mountlist_token); 606 TAILQ_FOREACH(msi, &mountscan_list, msi_entry) { 607 if (msi->msi_node == mp) { 608 if (msi->msi_how & MNTSCAN_FORWARD) 609 msi->msi_node = TAILQ_NEXT(mp, mnt_list); 610 else 611 msi->msi_node = TAILQ_PREV(mp, mntlist, 612 mnt_list); 613 } 614 } 615 TAILQ_REMOVE(&mountlist, mp, mnt_list); 616 lwkt_reltoken(&mountlist_token); 617 } 618 619 /* 620 * mountlist_exists (MP SAFE) 621 * 622 * Checks if a node exists in the mountlist. 623 * This function is mainly used by VFS quota code to check if a 624 * cached nullfs struct mount pointer is still valid at use time 625 * 626 * FIXME: there is no warranty the mp passed to that function 627 * will be the same one used by VFS_ACCOUNT() later 628 */ 629 int 630 mountlist_exists(struct mount *mp) 631 { 632 int node_exists = 0; 633 struct mount* lmp; 634 635 lwkt_gettoken_shared(&mountlist_token); 636 TAILQ_FOREACH(lmp, &mountlist, mnt_list) { 637 if (lmp == mp) { 638 node_exists = 1; 639 break; 640 } 641 } 642 lwkt_reltoken(&mountlist_token); 643 644 return(node_exists); 645 } 646 647 /* 648 * mountlist_scan 649 * 650 * Safely scan the mount points on the mount list. Each mountpoint 651 * is held across the callback. The callback is responsible for 652 * acquiring any further tokens or locks. 653 * 654 * Unless otherwise specified each mount point will be busied prior to the 655 * callback and unbusied afterwords. The callback may safely remove any 656 * mount point without interfering with the scan. If the current callback 657 * mount is removed the scanner will not attempt to unbusy it. 658 * 659 * If a mount node cannot be busied it is silently skipped. 660 * 661 * The callback return value is aggregated and a total is returned. A return 662 * value of < 0 is not aggregated and will terminate the scan. 663 * 664 * MNTSCAN_FORWARD - the mountlist is scanned in the forward direction 665 * MNTSCAN_REVERSE - the mountlist is scanned in reverse 666 * MNTSCAN_NOBUSY - the scanner will make the callback without busying 667 * the mount node. 668 * 669 * NOTE: mountlist_token is not held across the callback. 670 */ 671 int 672 mountlist_scan(int (*callback)(struct mount *, void *), void *data, int how) 673 { 674 struct mountscan_info info; 675 struct mount *mp; 676 int count; 677 int res; 678 679 lwkt_gettoken(&mountlist_token); 680 info.msi_how = how; 681 info.msi_node = NULL; /* paranoia */ 682 TAILQ_INSERT_TAIL(&mountscan_list, &info, msi_entry); 683 lwkt_reltoken(&mountlist_token); 684 685 res = 0; 686 lwkt_gettoken_shared(&mountlist_token); 687 688 if (how & MNTSCAN_FORWARD) { 689 info.msi_node = TAILQ_FIRST(&mountlist); 690 while ((mp = info.msi_node) != NULL) { 691 mount_hold(mp); 692 if (how & MNTSCAN_NOBUSY) { 693 lwkt_reltoken(&mountlist_token); 694 count = callback(mp, data); 695 lwkt_gettoken_shared(&mountlist_token); 696 } else if (vfs_busy(mp, LK_NOWAIT) == 0) { 697 lwkt_reltoken(&mountlist_token); 698 count = callback(mp, data); 699 lwkt_gettoken_shared(&mountlist_token); 700 if (mp == info.msi_node) 701 vfs_unbusy(mp); 702 } else { 703 count = 0; 704 } 705 mount_drop(mp); 706 if (count < 0) 707 break; 708 res += count; 709 if (mp == info.msi_node) 710 info.msi_node = TAILQ_NEXT(mp, mnt_list); 711 } 712 } else if (how & MNTSCAN_REVERSE) { 713 info.msi_node = TAILQ_LAST(&mountlist, mntlist); 714 while ((mp = info.msi_node) != NULL) { 715 mount_hold(mp); 716 if (how & MNTSCAN_NOBUSY) { 717 lwkt_reltoken(&mountlist_token); 718 count = callback(mp, data); 719 lwkt_gettoken_shared(&mountlist_token); 720 } else if (vfs_busy(mp, LK_NOWAIT) == 0) { 721 lwkt_reltoken(&mountlist_token); 722 count = callback(mp, data); 723 lwkt_gettoken_shared(&mountlist_token); 724 if (mp == info.msi_node) 725 vfs_unbusy(mp); 726 } else { 727 count = 0; 728 } 729 mount_drop(mp); 730 if (count < 0) 731 break; 732 res += count; 733 if (mp == info.msi_node) 734 info.msi_node = TAILQ_PREV(mp, mntlist, 735 mnt_list); 736 } 737 } 738 lwkt_reltoken(&mountlist_token); 739 740 lwkt_gettoken(&mountlist_token); 741 TAILQ_REMOVE(&mountscan_list, &info, msi_entry); 742 lwkt_reltoken(&mountlist_token); 743 744 return(res); 745 } 746 747 /* 748 * MOUNT RELATED VNODE FUNCTIONS 749 */ 750 751 static struct kproc_desc vnlru_kp = { 752 "vnlru", 753 vnlru_proc, 754 &vnlruthread 755 }; 756 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp); 757 758 /* 759 * Move a vnode from one mount queue to another. 760 */ 761 void 762 insmntque(struct vnode *vp, struct mount *mp) 763 { 764 struct mount *omp; 765 766 /* 767 * Delete from old mount point vnode list, if on one. 768 */ 769 if ((omp = vp->v_mount) != NULL) { 770 lwkt_gettoken(&omp->mnt_token); 771 KKASSERT(omp == vp->v_mount); 772 KASSERT(omp->mnt_nvnodelistsize > 0, 773 ("bad mount point vnode list size")); 774 vremovevnodemnt(vp); 775 omp->mnt_nvnodelistsize--; 776 lwkt_reltoken(&omp->mnt_token); 777 } 778 779 /* 780 * Insert into list of vnodes for the new mount point, if available. 781 * The 'end' of the LRU list is the vnode prior to mp->mnt_syncer. 782 */ 783 if (mp == NULL) { 784 vp->v_mount = NULL; 785 return; 786 } 787 lwkt_gettoken(&mp->mnt_token); 788 vp->v_mount = mp; 789 if (mp->mnt_syncer) { 790 TAILQ_INSERT_BEFORE(mp->mnt_syncer, vp, v_nmntvnodes); 791 } else { 792 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes); 793 } 794 mp->mnt_nvnodelistsize++; 795 lwkt_reltoken(&mp->mnt_token); 796 } 797 798 799 /* 800 * Scan the vnodes under a mount point and issue appropriate callbacks. 801 * 802 * The fastfunc() callback is called with just the mountlist token held 803 * (no vnode lock). It may not block and the vnode may be undergoing 804 * modifications while the caller is processing it. The vnode will 805 * not be entirely destroyed, however, due to the fact that the mountlist 806 * token is held. A return value < 0 skips to the next vnode without calling 807 * the slowfunc(), a return value > 0 terminates the loop. 808 * 809 * WARNING! The fastfunc() should not indirect through vp->v_object, the vp 810 * data structure is unstable when called from fastfunc(). 811 * 812 * The slowfunc() callback is called after the vnode has been successfully 813 * locked based on passed flags. The vnode is skipped if it gets rearranged 814 * or destroyed while blocking on the lock. A non-zero return value from 815 * the slow function terminates the loop. The slow function is allowed to 816 * arbitrarily block. The scanning code guarentees consistency of operation 817 * even if the slow function deletes or moves the node, or blocks and some 818 * other thread deletes or moves the node. 819 */ 820 int 821 vmntvnodescan( 822 struct mount *mp, 823 int flags, 824 int (*fastfunc)(struct mount *mp, struct vnode *vp, void *data), 825 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data), 826 void *data 827 ) { 828 struct vmntvnodescan_info info; 829 struct vnode *vp; 830 int r = 0; 831 int maxcount = mp->mnt_nvnodelistsize * 2; 832 int stopcount = 0; 833 int count = 0; 834 835 lwkt_gettoken(&mp->mnt_token); 836 837 /* 838 * If asked to do one pass stop after iterating available vnodes. 839 * Under heavy loads new vnodes can be added while we are scanning, 840 * so this isn't perfect. Create a slop factor of 2x. 841 */ 842 if (flags & VMSC_ONEPASS) 843 stopcount = mp->mnt_nvnodelistsize; 844 845 info.vp = TAILQ_FIRST(&mp->mnt_nvnodelist); 846 TAILQ_INSERT_TAIL(&mp->mnt_vnodescan_list, &info, entry); 847 848 while ((vp = info.vp) != NULL) { 849 if (--maxcount == 0) { 850 kprintf("Warning: excessive fssync iteration\n"); 851 maxcount = mp->mnt_nvnodelistsize * 2; 852 } 853 854 /* 855 * Skip if visible but not ready, or special (e.g. 856 * mp->mnt_syncer) 857 */ 858 if (vp->v_type == VNON) 859 goto next; 860 KKASSERT(vp->v_mount == mp); 861 862 /* 863 * Quick test. A negative return continues the loop without 864 * calling the slow test. 0 continues onto the slow test. 865 * A positive number aborts the loop. 866 */ 867 if (fastfunc) { 868 if ((r = fastfunc(mp, vp, data)) < 0) { 869 r = 0; 870 goto next; 871 } 872 if (r) 873 break; 874 } 875 876 /* 877 * Get a vxlock on the vnode, retry if it has moved or isn't 878 * in the mountlist where we expect it. 879 */ 880 if (slowfunc) { 881 int error; 882 883 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) { 884 case VMSC_GETVP: 885 error = vget(vp, LK_EXCLUSIVE); 886 break; 887 case VMSC_GETVP|VMSC_NOWAIT: 888 error = vget(vp, LK_EXCLUSIVE|LK_NOWAIT); 889 break; 890 case VMSC_GETVX: 891 vx_get(vp); 892 error = 0; 893 break; 894 default: 895 error = 0; 896 break; 897 } 898 if (error) 899 goto next; 900 /* 901 * Do not call the slow function if the vnode is 902 * invalid or if it was ripped out from under us 903 * while we (potentially) blocked. 904 */ 905 if (info.vp == vp && vp->v_type != VNON) 906 r = slowfunc(mp, vp, data); 907 908 /* 909 * Cleanup 910 */ 911 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) { 912 case VMSC_GETVP: 913 case VMSC_GETVP|VMSC_NOWAIT: 914 vput(vp); 915 break; 916 case VMSC_GETVX: 917 vx_put(vp); 918 break; 919 default: 920 break; 921 } 922 if (r != 0) 923 break; 924 } 925 926 next: 927 /* 928 * Yield after some processing. Depending on the number 929 * of vnodes, we might wind up running for a long time. 930 * Because threads are not preemptable, time critical 931 * userland processes might starve. Give them a chance 932 * now and then. 933 */ 934 if (++count == 10000) { 935 /* 936 * We really want to yield a bit, so we simply 937 * sleep a tick 938 */ 939 tsleep(mp, 0, "vnodescn", 1); 940 count = 0; 941 } 942 943 /* 944 * If doing one pass this decrements to zero. If it starts 945 * at zero it is effectively unlimited for the purposes of 946 * this loop. 947 */ 948 if (--stopcount == 0) 949 break; 950 951 /* 952 * Iterate. If the vnode was ripped out from under us 953 * info.vp will already point to the next vnode, otherwise 954 * we have to obtain the next valid vnode ourselves. 955 */ 956 if (info.vp == vp) 957 info.vp = TAILQ_NEXT(vp, v_nmntvnodes); 958 } 959 960 TAILQ_REMOVE(&mp->mnt_vnodescan_list, &info, entry); 961 lwkt_reltoken(&mp->mnt_token); 962 return(r); 963 } 964 965 /* 966 * Remove any vnodes in the vnode table belonging to mount point mp. 967 * 968 * If FORCECLOSE is not specified, there should not be any active ones, 969 * return error if any are found (nb: this is a user error, not a 970 * system error). If FORCECLOSE is specified, detach any active vnodes 971 * that are found. 972 * 973 * If WRITECLOSE is set, only flush out regular file vnodes open for 974 * writing. 975 * 976 * SKIPSYSTEM causes any vnodes marked VSYSTEM to be skipped. 977 * 978 * `rootrefs' specifies the base reference count for the root vnode 979 * of this filesystem. The root vnode is considered busy if its 980 * v_refcnt exceeds this value. On a successful return, vflush() 981 * will call vrele() on the root vnode exactly rootrefs times. 982 * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must 983 * be zero. 984 */ 985 static int debug_busyprt = 0; /* print out busy vnodes */ 986 SYSCTL_INT(_vfs, OID_AUTO, debug_busyprt, CTLFLAG_RW, &debug_busyprt, 0, ""); 987 988 static int vflush_scan(struct mount *mp, struct vnode *vp, void *data); 989 990 struct vflush_info { 991 int flags; 992 int busy; 993 thread_t td; 994 }; 995 996 int 997 vflush(struct mount *mp, int rootrefs, int flags) 998 { 999 struct thread *td = curthread; /* XXX */ 1000 struct vnode *rootvp = NULL; 1001 int error; 1002 struct vflush_info vflush_info; 1003 1004 if (rootrefs > 0) { 1005 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0, 1006 ("vflush: bad args")); 1007 /* 1008 * Get the filesystem root vnode. We can vput() it 1009 * immediately, since with rootrefs > 0, it won't go away. 1010 */ 1011 if ((error = VFS_ROOT(mp, &rootvp)) != 0) { 1012 if ((flags & FORCECLOSE) == 0) 1013 return (error); 1014 rootrefs = 0; 1015 /* continue anyway */ 1016 } 1017 if (rootrefs) 1018 vput(rootvp); 1019 } 1020 1021 vflush_info.busy = 0; 1022 vflush_info.flags = flags; 1023 vflush_info.td = td; 1024 vmntvnodescan(mp, VMSC_GETVX, NULL, vflush_scan, &vflush_info); 1025 1026 if (rootrefs > 0 && (flags & FORCECLOSE) == 0) { 1027 /* 1028 * If just the root vnode is busy, and if its refcount 1029 * is equal to `rootrefs', then go ahead and kill it. 1030 */ 1031 KASSERT(vflush_info.busy > 0, ("vflush: not busy")); 1032 KASSERT(VREFCNT(rootvp) >= rootrefs, ("vflush: rootrefs")); 1033 if (vflush_info.busy == 1 && VREFCNT(rootvp) == rootrefs) { 1034 vx_lock(rootvp); 1035 vgone_vxlocked(rootvp); 1036 vx_unlock(rootvp); 1037 vflush_info.busy = 0; 1038 } 1039 } 1040 if (vflush_info.busy) 1041 return (EBUSY); 1042 for (; rootrefs > 0; rootrefs--) 1043 vrele(rootvp); 1044 return (0); 1045 } 1046 1047 /* 1048 * The scan callback is made with an VX locked vnode. 1049 */ 1050 static int 1051 vflush_scan(struct mount *mp, struct vnode *vp, void *data) 1052 { 1053 struct vflush_info *info = data; 1054 struct vattr vattr; 1055 int flags = info->flags; 1056 1057 /* 1058 * Generally speaking try to deactivate on 0 refs (catch-all) 1059 */ 1060 atomic_set_int(&vp->v_refcnt, VREF_FINALIZE); 1061 1062 /* 1063 * Skip over a vnodes marked VSYSTEM. 1064 */ 1065 if ((flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) { 1066 return(0); 1067 } 1068 1069 /* 1070 * Do not force-close VCHR or VBLK vnodes 1071 */ 1072 if (vp->v_type == VCHR || vp->v_type == VBLK) 1073 flags &= ~(WRITECLOSE|FORCECLOSE); 1074 1075 /* 1076 * If WRITECLOSE is set, flush out unlinked but still open 1077 * files (even if open only for reading) and regular file 1078 * vnodes open for writing. 1079 */ 1080 if ((flags & WRITECLOSE) && 1081 (vp->v_type == VNON || 1082 (VOP_GETATTR(vp, &vattr) == 0 && 1083 vattr.va_nlink > 0)) && 1084 (vp->v_writecount == 0 || vp->v_type != VREG)) { 1085 return(0); 1086 } 1087 1088 /* 1089 * If we are the only holder (refcnt of 1) or the vnode is in 1090 * termination (refcnt < 0), we can vgone the vnode. 1091 */ 1092 if (VREFCNT(vp) <= 1) { 1093 vgone_vxlocked(vp); 1094 return(0); 1095 } 1096 1097 /* 1098 * If FORCECLOSE is set, forcibly destroy the vnode and then move 1099 * it to a dummymount structure so vop_*() functions don't deref 1100 * a NULL pointer. 1101 */ 1102 if (flags & FORCECLOSE) { 1103 vhold(vp); 1104 vgone_vxlocked(vp); 1105 if (vp->v_mount == NULL) 1106 insmntque(vp, &dummymount); 1107 vdrop(vp); 1108 return(0); 1109 } 1110 if (vp->v_type == VCHR || vp->v_type == VBLK) 1111 kprintf("vflush: Warning, cannot destroy busy device vnode\n"); 1112 if (debug_busyprt) { 1113 const char *filename; 1114 1115 spin_lock(&vp->v_spin); 1116 filename = TAILQ_FIRST(&vp->v_namecache) ? 1117 TAILQ_FIRST(&vp->v_namecache)->nc_name : "?"; 1118 spin_unlock(&vp->v_spin); 1119 kprintf("vflush: busy vnode (%p) %s\n", vp, filename); 1120 } 1121 ++info->busy; 1122 return(0); 1123 } 1124 1125 void 1126 add_bio_ops(struct bio_ops *ops) 1127 { 1128 TAILQ_INSERT_TAIL(&bio_ops_list, ops, entry); 1129 } 1130 1131 void 1132 rem_bio_ops(struct bio_ops *ops) 1133 { 1134 TAILQ_REMOVE(&bio_ops_list, ops, entry); 1135 } 1136 1137 /* 1138 * This calls the bio_ops io_sync function either for a mount point 1139 * or generally. 1140 * 1141 * WARNING: softdeps is weirdly coded and just isn't happy unless 1142 * io_sync is called with a NULL mount from the general syncing code. 1143 */ 1144 void 1145 bio_ops_sync(struct mount *mp) 1146 { 1147 struct bio_ops *ops; 1148 1149 if (mp) { 1150 if ((ops = mp->mnt_bioops) != NULL) 1151 ops->io_sync(mp); 1152 } else { 1153 TAILQ_FOREACH(ops, &bio_ops_list, entry) { 1154 ops->io_sync(NULL); 1155 } 1156 } 1157 } 1158 1159 /* 1160 * Lookup a mount point by nch 1161 */ 1162 struct mount * 1163 mount_get_by_nc(struct namecache *ncp) 1164 { 1165 struct mount *mp = NULL; 1166 1167 lwkt_gettoken_shared(&mountlist_token); 1168 TAILQ_FOREACH(mp, &mountlist, mnt_list) { 1169 if (ncp == mp->mnt_ncmountpt.ncp) 1170 break; 1171 } 1172 lwkt_reltoken(&mountlist_token); 1173 1174 return (mp); 1175 } 1176 1177