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, 1); 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 int slot; 161 162 lwkt_gettoken(&syncer_token); 163 164 if (vp->v_flag & VONWORKLST) 165 LIST_REMOVE(vp, v_synclist); 166 if (delay > syncer_maxdelay - 2) 167 delay = syncer_maxdelay - 2; 168 slot = (syncer_delayno + delay) & syncer_mask; 169 170 LIST_INSERT_HEAD(&syncer_workitem_pending[slot], vp, v_synclist); 171 vsetflags(vp, VONWORKLST); 172 173 lwkt_reltoken(&syncer_token); 174 } 175 176 struct thread *updatethread; 177 static void sched_sync (void); 178 static struct kproc_desc up_kp = { 179 "syncer", 180 sched_sync, 181 &updatethread 182 }; 183 SYSINIT(syncer, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &up_kp) 184 185 /* 186 * System filesystem synchronizer daemon. 187 */ 188 void 189 sched_sync(void) 190 { 191 struct thread *td = curthread; 192 struct synclist *slp; 193 struct vnode *vp; 194 long starttime; 195 196 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td, 197 SHUTDOWN_PRI_LAST); 198 199 for (;;) { 200 kproc_suspend_loop(); 201 202 starttime = time_second; 203 lwkt_gettoken(&syncer_token); 204 205 /* 206 * Push files whose dirty time has expired. Be careful 207 * of interrupt race on slp queue. 208 */ 209 slp = &syncer_workitem_pending[syncer_delayno]; 210 syncer_delayno += 1; 211 if (syncer_delayno == syncer_maxdelay) 212 syncer_delayno = 0; 213 214 while ((vp = LIST_FIRST(slp)) != NULL) { 215 if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 216 VOP_FSYNC(vp, MNT_LAZY, 0); 217 vput(vp); 218 } 219 220 /* 221 * If the vnode is still at the head of the list 222 * we were not able to completely flush it. To 223 * give other vnodes a fair shake we move it to 224 * a later slot. 225 * 226 * Note that v_tag VT_VFS vnodes can remain on the 227 * worklist with no dirty blocks, but sync_fsync() 228 * moves it to a later slot so we will never see it 229 * here. 230 */ 231 if (LIST_FIRST(slp) == vp) { 232 lwkt_gettoken(&vp->v_token); 233 if (LIST_FIRST(slp) == vp) { 234 if (RB_EMPTY(&vp->v_rbdirty_tree) && 235 !vn_isdisk(vp, NULL)) { 236 panic("sched_sync: fsync " 237 "failed vp %p tag %d", 238 vp, vp->v_tag); 239 } 240 vn_syncer_add_to_worklist(vp, syncdelay); 241 } 242 lwkt_reltoken(&vp->v_token); 243 } 244 } 245 lwkt_reltoken(&syncer_token); 246 247 /* 248 * Do sync processing for each mount. 249 */ 250 bio_ops_sync(NULL); 251 252 /* 253 * The variable rushjob allows the kernel to speed up the 254 * processing of the filesystem syncer process. A rushjob 255 * value of N tells the filesystem syncer to process the next 256 * N seconds worth of work on its queue ASAP. Currently rushjob 257 * is used by the soft update code to speed up the filesystem 258 * syncer process when the incore state is getting so far 259 * ahead of the disk that the kernel memory pool is being 260 * threatened with exhaustion. 261 */ 262 if (rushjob > 0) { 263 rushjob -= 1; 264 continue; 265 } 266 /* 267 * If it has taken us less than a second to process the 268 * current work, then wait. Otherwise start right over 269 * again. We can still lose time if any single round 270 * takes more than two seconds, but it does not really 271 * matter as we are just trying to generally pace the 272 * filesystem activity. 273 */ 274 if (time_second == starttime) 275 tsleep(&lbolt_syncer, 0, "syncer", 0); 276 } 277 } 278 279 /* 280 * Request the syncer daemon to speed up its work. 281 * We never push it to speed up more than half of its 282 * normal turn time, otherwise it could take over the cpu. 283 * 284 * YYY wchan field protected by the BGL. 285 */ 286 int 287 speedup_syncer(void) 288 { 289 /* 290 * Don't bother protecting the test. unsleep_and_wakeup_thread() 291 * will only do something real if the thread is in the right state. 292 */ 293 wakeup(&lbolt_syncer); 294 if (rushjob < syncdelay / 2) { 295 rushjob += 1; 296 stat_rush_requests += 1; 297 return (1); 298 } 299 return(0); 300 } 301 302 /* 303 * Routine to create and manage a filesystem syncer vnode. 304 */ 305 static int sync_close(struct vop_close_args *); 306 static int sync_fsync(struct vop_fsync_args *); 307 static int sync_inactive(struct vop_inactive_args *); 308 static int sync_reclaim (struct vop_reclaim_args *); 309 static int sync_print(struct vop_print_args *); 310 311 static struct vop_ops sync_vnode_vops = { 312 .vop_default = vop_eopnotsupp, 313 .vop_close = sync_close, 314 .vop_fsync = sync_fsync, 315 .vop_inactive = sync_inactive, 316 .vop_reclaim = sync_reclaim, 317 .vop_print = sync_print, 318 }; 319 320 static struct vop_ops *sync_vnode_vops_p = &sync_vnode_vops; 321 322 VNODEOP_SET(sync_vnode_vops); 323 324 /* 325 * Create a new filesystem syncer vnode for the specified mount point. 326 * This vnode is placed on the worklist and is responsible for sync'ing 327 * the filesystem. 328 * 329 * NOTE: read-only mounts are also placed on the worklist. The filesystem 330 * sync code is also responsible for cleaning up vnodes. 331 */ 332 int 333 vfs_allocate_syncvnode(struct mount *mp) 334 { 335 struct vnode *vp; 336 static long start, incr, next; 337 int error; 338 339 /* Allocate a new vnode */ 340 error = getspecialvnode(VT_VFS, mp, &sync_vnode_vops_p, &vp, 0, 0); 341 if (error) { 342 mp->mnt_syncer = NULL; 343 return (error); 344 } 345 vp->v_type = VNON; 346 /* 347 * Place the vnode onto the syncer worklist. We attempt to 348 * scatter them about on the list so that they will go off 349 * at evenly distributed times even if all the filesystems 350 * are mounted at once. 351 */ 352 next += incr; 353 if (next == 0 || next > syncer_maxdelay) { 354 start /= 2; 355 incr /= 2; 356 if (start == 0) { 357 start = syncer_maxdelay / 2; 358 incr = syncer_maxdelay; 359 } 360 next = start; 361 } 362 vn_syncer_add_to_worklist(vp, syncdelay > 0 ? next % syncdelay : 0); 363 364 /* 365 * The mnt_syncer field inherits the vnode reference, which is 366 * held until later decomissioning. 367 */ 368 mp->mnt_syncer = vp; 369 vx_unlock(vp); 370 return (0); 371 } 372 373 static int 374 sync_close(struct vop_close_args *ap) 375 { 376 return (0); 377 } 378 379 /* 380 * Do a lazy sync of the filesystem. 381 * 382 * sync_fsync { struct vnode *a_vp, int a_waitfor } 383 */ 384 static int 385 sync_fsync(struct vop_fsync_args *ap) 386 { 387 struct vnode *syncvp = ap->a_vp; 388 struct mount *mp = syncvp->v_mount; 389 int asyncflag; 390 391 /* 392 * We only need to do something if this is a lazy evaluation. 393 */ 394 if (ap->a_waitfor != MNT_LAZY) 395 return (0); 396 397 /* 398 * Move ourselves to the back of the sync list. 399 */ 400 vn_syncer_add_to_worklist(syncvp, syncdelay); 401 402 /* 403 * Walk the list of vnodes pushing all that are dirty and 404 * not already on the sync list, and freeing vnodes which have 405 * no refs and whos VM objects are empty. vfs_msync() handles 406 * the VM issues and must be called whether the mount is readonly 407 * or not. 408 */ 409 if (vfs_busy(mp, LK_NOWAIT) != 0) 410 return (0); 411 if (mp->mnt_flag & MNT_RDONLY) { 412 vfs_msync(mp, MNT_NOWAIT); 413 } else { 414 asyncflag = mp->mnt_flag & MNT_ASYNC; 415 mp->mnt_flag &= ~MNT_ASYNC; /* ZZZ hack */ 416 vfs_msync(mp, MNT_NOWAIT); 417 VFS_SYNC(mp, MNT_LAZY); 418 if (asyncflag) 419 mp->mnt_flag |= MNT_ASYNC; 420 } 421 vfs_unbusy(mp); 422 return (0); 423 } 424 425 /* 426 * The syncer vnode is no longer referenced. 427 * 428 * sync_inactive { struct vnode *a_vp, struct proc *a_p } 429 */ 430 static int 431 sync_inactive(struct vop_inactive_args *ap) 432 { 433 vgone_vxlocked(ap->a_vp); 434 return (0); 435 } 436 437 /* 438 * The syncer vnode is no longer needed and is being decommissioned. 439 * This can only occur when the last reference has been released on 440 * mp->mnt_syncer, so mp->mnt_syncer had better be NULL. 441 * 442 * Modifications to the worklist must be protected with a critical 443 * section. 444 * 445 * sync_reclaim { struct vnode *a_vp } 446 */ 447 static int 448 sync_reclaim(struct vop_reclaim_args *ap) 449 { 450 struct vnode *vp = ap->a_vp; 451 452 lwkt_gettoken(&syncer_token); 453 KKASSERT(vp->v_mount->mnt_syncer != vp); 454 if (vp->v_flag & VONWORKLST) { 455 LIST_REMOVE(vp, v_synclist); 456 vclrflags(vp, VONWORKLST); 457 } 458 lwkt_reltoken(&syncer_token); 459 460 return (0); 461 } 462 463 /* 464 * Print out a syncer vnode. 465 * 466 * sync_print { struct vnode *a_vp } 467 */ 468 static int 469 sync_print(struct vop_print_args *ap) 470 { 471 struct vnode *vp = ap->a_vp; 472 473 kprintf("syncer vnode"); 474 lockmgr_printinfo(&vp->v_lock); 475 kprintf("\n"); 476 return (0); 477 } 478 479