1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * @(#)vfs_subr.c 8.31 (Berkeley) 5/26/95 41 * $FreeBSD: src/sys/kern/vfs_subr.c,v 1.249.2.30 2003/04/04 20:35:57 tegge Exp $ 42 * $DragonFly: src/sys/kern/vfs_sync.c,v 1.18 2008/05/18 05:54:25 dillon Exp $ 43 */ 44 45 /* 46 * External virtual filesystem routines 47 */ 48 #include "opt_ddb.h" 49 50 #include <sys/param.h> 51 #include <sys/systm.h> 52 #include <sys/buf.h> 53 #include <sys/conf.h> 54 #include <sys/dirent.h> 55 #include <sys/domain.h> 56 #include <sys/eventhandler.h> 57 #include <sys/fcntl.h> 58 #include <sys/kernel.h> 59 #include <sys/kthread.h> 60 #include <sys/malloc.h> 61 #include <sys/mbuf.h> 62 #include <sys/mount.h> 63 #include <sys/proc.h> 64 #include <sys/namei.h> 65 #include <sys/reboot.h> 66 #include <sys/socket.h> 67 #include <sys/stat.h> 68 #include <sys/sysctl.h> 69 #include <sys/syslog.h> 70 #include <sys/vmmeter.h> 71 #include <sys/vnode.h> 72 73 #include <machine/limits.h> 74 75 #include <vm/vm.h> 76 #include <vm/vm_object.h> 77 #include <vm/vm_extern.h> 78 #include <vm/vm_kern.h> 79 #include <vm/pmap.h> 80 #include <vm/vm_map.h> 81 #include <vm/vm_page.h> 82 #include <vm/vm_pager.h> 83 #include <vm/vnode_pager.h> 84 85 #include <sys/buf2.h> 86 #include <sys/thread2.h> 87 #include <sys/mplock2.h> 88 89 /* 90 * The workitem queue. 91 */ 92 #define SYNCER_MAXDELAY 32 93 static int syncer_maxdelay = SYNCER_MAXDELAY; /* maximum delay time */ 94 time_t syncdelay = 30; /* max time to delay syncing data */ 95 SYSCTL_INT(_kern, OID_AUTO, syncdelay, CTLFLAG_RW, 96 &syncdelay, 0, "VFS data synchronization delay"); 97 time_t filedelay = 30; /* time to delay syncing files */ 98 SYSCTL_INT(_kern, OID_AUTO, filedelay, CTLFLAG_RW, 99 &filedelay, 0, "File synchronization delay"); 100 time_t dirdelay = 29; /* time to delay syncing directories */ 101 SYSCTL_INT(_kern, OID_AUTO, dirdelay, CTLFLAG_RW, 102 &dirdelay, 0, "Directory synchronization delay"); 103 time_t metadelay = 28; /* time to delay syncing metadata */ 104 SYSCTL_INT(_kern, OID_AUTO, metadelay, CTLFLAG_RW, 105 &metadelay, 0, "VFS metadata synchronization delay"); 106 static int rushjob; /* number of slots to run ASAP */ 107 static int stat_rush_requests; /* number of times I/O speeded up */ 108 SYSCTL_INT(_debug, OID_AUTO, rush_requests, CTLFLAG_RW, 109 &stat_rush_requests, 0, ""); 110 111 static int syncer_delayno = 0; 112 static long syncer_mask; 113 static struct lwkt_token syncer_token; 114 LIST_HEAD(synclist, vnode); 115 static struct synclist *syncer_workitem_pending; 116 117 /* 118 * Called from vfsinit() 119 */ 120 void 121 vfs_sync_init(void) 122 { 123 syncer_workitem_pending = hashinit(syncer_maxdelay, M_DEVBUF, 124 &syncer_mask); 125 syncer_maxdelay = syncer_mask + 1; 126 lwkt_token_init(&syncer_token, 1, "syncer"); 127 } 128 129 /* 130 * The workitem queue. 131 * 132 * It is useful to delay writes of file data and filesystem metadata 133 * for tens of seconds so that quickly created and deleted files need 134 * not waste disk bandwidth being created and removed. To realize this, 135 * we append vnodes to a "workitem" queue. When running with a soft 136 * updates implementation, most pending metadata dependencies should 137 * not wait for more than a few seconds. Thus, mounted on block devices 138 * are delayed only about a half the time that file data is delayed. 139 * Similarly, directory updates are more critical, so are only delayed 140 * about a third the time that file data is delayed. Thus, there are 141 * SYNCER_MAXDELAY queues that are processed round-robin at a rate of 142 * one each second (driven off the filesystem syncer process). The 143 * syncer_delayno variable indicates the next queue that is to be processed. 144 * Items that need to be processed soon are placed in this queue: 145 * 146 * syncer_workitem_pending[syncer_delayno] 147 * 148 * A delay of fifteen seconds is done by placing the request fifteen 149 * entries later in the queue: 150 * 151 * syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask] 152 * 153 */ 154 155 /* 156 * Add an item to the syncer work queue. 157 * 158 * WARNING: Cannot get vp->v_token here if not already held, we must 159 * depend on the syncer_token (which might already be held by 160 * the caller) to protect v_synclist and VONWORKLST. 161 * 162 * MPSAFE 163 */ 164 void 165 vn_syncer_add(struct vnode *vp, int delay) 166 { 167 int slot; 168 169 lwkt_gettoken(&syncer_token); 170 171 if (vp->v_flag & VONWORKLST) 172 LIST_REMOVE(vp, v_synclist); 173 if (delay > syncer_maxdelay - 2) 174 delay = syncer_maxdelay - 2; 175 slot = (syncer_delayno + delay) & syncer_mask; 176 177 LIST_INSERT_HEAD(&syncer_workitem_pending[slot], vp, v_synclist); 178 vsetflags(vp, VONWORKLST); 179 180 lwkt_reltoken(&syncer_token); 181 } 182 183 /* 184 * Removes the vnode from the syncer list. Since we might block while 185 * acquiring the syncer_token we have to recheck conditions. 186 * 187 * vp->v_token held on call 188 */ 189 void 190 vn_syncer_remove(struct vnode *vp) 191 { 192 lwkt_gettoken(&syncer_token); 193 194 if ((vp->v_flag & VONWORKLST) && RB_EMPTY(&vp->v_rbdirty_tree)) { 195 vclrflags(vp, VONWORKLST); 196 LIST_REMOVE(vp, v_synclist); 197 } 198 199 lwkt_reltoken(&syncer_token); 200 } 201 202 struct thread *updatethread; 203 204 /* 205 * System filesystem synchronizer daemon. 206 */ 207 static void 208 syncer_thread(void) 209 { 210 struct thread *td = curthread; 211 struct synclist *slp; 212 struct vnode *vp; 213 long starttime; 214 215 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td, 216 SHUTDOWN_PRI_LAST); 217 for (;;) { 218 kproc_suspend_loop(); 219 220 starttime = time_second; 221 lwkt_gettoken(&syncer_token); 222 223 /* 224 * Push files whose dirty time has expired. Be careful 225 * of interrupt race on slp queue. 226 */ 227 slp = &syncer_workitem_pending[syncer_delayno]; 228 syncer_delayno += 1; 229 if (syncer_delayno == syncer_maxdelay) 230 syncer_delayno = 0; 231 232 while ((vp = LIST_FIRST(slp)) != NULL) { 233 if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 234 VOP_FSYNC(vp, MNT_LAZY, 0); 235 vput(vp); 236 } 237 238 /* 239 * vp is stale but can still be used if we can 240 * verify that it remains at the head of the list. 241 * Be careful not to try to get vp->v_token as 242 * vp can become stale if this blocks. 243 * 244 * If the vp is still at the head of the list were 245 * unable to completely flush it and move it to 246 * a later slot to give other vnodes a fair shot. 247 * 248 * Note that v_tag VT_VFS vnodes can remain on the 249 * worklist with no dirty blocks, but sync_fsync() 250 * moves it to a later slot so we will never see it 251 * here. 252 * 253 * It is possible to race a vnode with no dirty 254 * buffers being removed from the list. If this 255 * occurs we will move the vnode in the synclist 256 * and then the other thread will remove it. Do 257 * not try to remove it here. 258 */ 259 if (LIST_FIRST(slp) == vp) 260 vn_syncer_add(vp, syncdelay); 261 } 262 lwkt_reltoken(&syncer_token); 263 264 /* 265 * Do sync processing for each mount. 266 */ 267 bio_ops_sync(NULL); 268 269 /* 270 * The variable rushjob allows the kernel to speed up the 271 * processing of the filesystem syncer process. A rushjob 272 * value of N tells the filesystem syncer to process the next 273 * N seconds worth of work on its queue ASAP. Currently rushjob 274 * is used by the soft update code to speed up the filesystem 275 * syncer process when the incore state is getting so far 276 * ahead of the disk that the kernel memory pool is being 277 * threatened with exhaustion. 278 */ 279 if (rushjob > 0) { 280 atomic_subtract_int(&rushjob, 1); 281 continue; 282 } 283 /* 284 * If it has taken us less than a second to process the 285 * current work, then wait. Otherwise start right over 286 * again. We can still lose time if any single round 287 * takes more than two seconds, but it does not really 288 * matter as we are just trying to generally pace the 289 * filesystem activity. 290 */ 291 if (time_second == starttime) 292 tsleep(&lbolt_syncer, 0, "syncer", 0); 293 } 294 } 295 296 static struct kproc_desc up_kp = { 297 "syncer", 298 syncer_thread, 299 &updatethread 300 }; 301 SYSINIT(syncer, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &up_kp) 302 303 /* 304 * Request the syncer daemon to speed up its work. 305 * We never push it to speed up more than half of its 306 * normal turn time, otherwise it could take over the cpu. 307 */ 308 int 309 speedup_syncer(void) 310 { 311 /* 312 * Don't bother protecting the test. unsleep_and_wakeup_thread() 313 * will only do something real if the thread is in the right state. 314 */ 315 wakeup(&lbolt_syncer); 316 if (rushjob < syncdelay / 2) { 317 atomic_add_int(&rushjob, 1); 318 stat_rush_requests += 1; 319 return (1); 320 } 321 return(0); 322 } 323 324 /* 325 * Routine to create and manage a filesystem syncer vnode. 326 */ 327 static int sync_close(struct vop_close_args *); 328 static int sync_fsync(struct vop_fsync_args *); 329 static int sync_inactive(struct vop_inactive_args *); 330 static int sync_reclaim (struct vop_reclaim_args *); 331 static int sync_print(struct vop_print_args *); 332 333 static struct vop_ops sync_vnode_vops = { 334 .vop_default = vop_eopnotsupp, 335 .vop_close = sync_close, 336 .vop_fsync = sync_fsync, 337 .vop_inactive = sync_inactive, 338 .vop_reclaim = sync_reclaim, 339 .vop_print = sync_print, 340 }; 341 342 static struct vop_ops *sync_vnode_vops_p = &sync_vnode_vops; 343 344 VNODEOP_SET(sync_vnode_vops); 345 346 /* 347 * Create a new filesystem syncer vnode for the specified mount point. 348 * This vnode is placed on the worklist and is responsible for sync'ing 349 * the filesystem. 350 * 351 * NOTE: read-only mounts are also placed on the worklist. The filesystem 352 * sync code is also responsible for cleaning up vnodes. 353 */ 354 int 355 vfs_allocate_syncvnode(struct mount *mp) 356 { 357 struct vnode *vp; 358 static long start, incr, next; 359 int error; 360 361 /* Allocate a new vnode */ 362 error = getspecialvnode(VT_VFS, mp, &sync_vnode_vops_p, &vp, 0, 0); 363 if (error) { 364 mp->mnt_syncer = NULL; 365 return (error); 366 } 367 vp->v_type = VNON; 368 /* 369 * Place the vnode onto the syncer worklist. We attempt to 370 * scatter them about on the list so that they will go off 371 * at evenly distributed times even if all the filesystems 372 * are mounted at once. 373 */ 374 next += incr; 375 if (next == 0 || next > syncer_maxdelay) { 376 start /= 2; 377 incr /= 2; 378 if (start == 0) { 379 start = syncer_maxdelay / 2; 380 incr = syncer_maxdelay; 381 } 382 next = start; 383 } 384 vn_syncer_add(vp, syncdelay > 0 ? next % syncdelay : 0); 385 386 /* 387 * The mnt_syncer field inherits the vnode reference, which is 388 * held until later decomissioning. 389 */ 390 mp->mnt_syncer = vp; 391 vx_unlock(vp); 392 return (0); 393 } 394 395 static int 396 sync_close(struct vop_close_args *ap) 397 { 398 return (0); 399 } 400 401 /* 402 * Do a lazy sync of the filesystem. 403 * 404 * sync_fsync { struct vnode *a_vp, int a_waitfor } 405 */ 406 static int 407 sync_fsync(struct vop_fsync_args *ap) 408 { 409 struct vnode *syncvp = ap->a_vp; 410 struct mount *mp = syncvp->v_mount; 411 int asyncflag; 412 413 /* 414 * We only need to do something if this is a lazy evaluation. 415 */ 416 if (ap->a_waitfor != MNT_LAZY) 417 return (0); 418 419 /* 420 * Move ourselves to the back of the sync list. 421 */ 422 vn_syncer_add(syncvp, syncdelay); 423 424 /* 425 * Walk the list of vnodes pushing all that are dirty and 426 * not already on the sync list, and freeing vnodes which have 427 * no refs and whos VM objects are empty. vfs_msync() handles 428 * the VM issues and must be called whether the mount is readonly 429 * or not. 430 */ 431 if (vfs_busy(mp, LK_NOWAIT) != 0) 432 return (0); 433 if (mp->mnt_flag & MNT_RDONLY) { 434 vfs_msync(mp, MNT_NOWAIT); 435 } else { 436 asyncflag = mp->mnt_flag & MNT_ASYNC; 437 mp->mnt_flag &= ~MNT_ASYNC; /* ZZZ hack */ 438 vfs_msync(mp, MNT_NOWAIT); 439 VFS_SYNC(mp, MNT_LAZY); 440 if (asyncflag) 441 mp->mnt_flag |= MNT_ASYNC; 442 } 443 vfs_unbusy(mp); 444 return (0); 445 } 446 447 /* 448 * The syncer vnode is no longer referenced. 449 * 450 * sync_inactive { struct vnode *a_vp, struct proc *a_p } 451 */ 452 static int 453 sync_inactive(struct vop_inactive_args *ap) 454 { 455 vgone_vxlocked(ap->a_vp); 456 return (0); 457 } 458 459 /* 460 * The syncer vnode is no longer needed and is being decommissioned. 461 * This can only occur when the last reference has been released on 462 * mp->mnt_syncer, so mp->mnt_syncer had better be NULL. 463 * 464 * Modifications to the worklist must be protected with a critical 465 * section. 466 * 467 * sync_reclaim { struct vnode *a_vp } 468 */ 469 static int 470 sync_reclaim(struct vop_reclaim_args *ap) 471 { 472 struct vnode *vp = ap->a_vp; 473 474 lwkt_gettoken(&syncer_token); 475 KKASSERT(vp->v_mount->mnt_syncer != vp); 476 if (vp->v_flag & VONWORKLST) { 477 LIST_REMOVE(vp, v_synclist); 478 vclrflags(vp, VONWORKLST); 479 } 480 lwkt_reltoken(&syncer_token); 481 482 return (0); 483 } 484 485 /* 486 * Print out a syncer vnode. 487 * 488 * sync_print { struct vnode *a_vp } 489 */ 490 static int 491 sync_print(struct vop_print_args *ap) 492 { 493 struct vnode *vp = ap->a_vp; 494 495 kprintf("syncer vnode"); 496 lockmgr_printinfo(&vp->v_lock); 497 kprintf("\n"); 498 return (0); 499 } 500 501