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