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 1.8 2005/11/14 18:50:05 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 LIST_HEAD(synclist, vnode); 111 static struct synclist *syncer_workitem_pending; 112 113 /* 114 * Called from vfsinit() 115 */ 116 void 117 vfs_sync_init(void) 118 { 119 syncer_workitem_pending = hashinit(syncer_maxdelay, M_DEVBUF, 120 &syncer_mask); 121 syncer_maxdelay = syncer_mask + 1; 122 } 123 124 /* 125 * The workitem queue. 126 * 127 * It is useful to delay writes of file data and filesystem metadata 128 * for tens of seconds so that quickly created and deleted files need 129 * not waste disk bandwidth being created and removed. To realize this, 130 * we append vnodes to a "workitem" queue. When running with a soft 131 * updates implementation, most pending metadata dependencies should 132 * not wait for more than a few seconds. Thus, mounted on block devices 133 * are delayed only about a half the time that file data is delayed. 134 * Similarly, directory updates are more critical, so are only delayed 135 * about a third the time that file data is delayed. Thus, there are 136 * SYNCER_MAXDELAY queues that are processed round-robin at a rate of 137 * one each second (driven off the filesystem syncer process). The 138 * syncer_delayno variable indicates the next queue that is to be processed. 139 * Items that need to be processed soon are placed in this queue: 140 * 141 * syncer_workitem_pending[syncer_delayno] 142 * 143 * A delay of fifteen seconds is done by placing the request fifteen 144 * entries later in the queue: 145 * 146 * syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask] 147 * 148 */ 149 150 /* 151 * Add an item to the syncer work queue. 152 */ 153 void 154 vn_syncer_add_to_worklist(struct vnode *vp, int delay) 155 { 156 int slot; 157 158 crit_enter(); 159 160 if (vp->v_flag & VONWORKLST) { 161 LIST_REMOVE(vp, v_synclist); 162 } 163 164 if (delay > syncer_maxdelay - 2) 165 delay = syncer_maxdelay - 2; 166 slot = (syncer_delayno + delay) & syncer_mask; 167 168 LIST_INSERT_HEAD(&syncer_workitem_pending[slot], vp, v_synclist); 169 vp->v_flag |= VONWORKLST; 170 crit_exit(); 171 } 172 173 struct thread *updatethread; 174 static void sched_sync (void); 175 static struct kproc_desc up_kp = { 176 "syncer", 177 sched_sync, 178 &updatethread 179 }; 180 SYSINIT(syncer, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &up_kp) 181 182 /* 183 * System filesystem synchronizer daemon. 184 */ 185 void 186 sched_sync(void) 187 { 188 struct synclist *slp; 189 struct vnode *vp; 190 long starttime; 191 struct thread *td = curthread; 192 193 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td, 194 SHUTDOWN_PRI_LAST); 195 196 for (;;) { 197 kproc_suspend_loop(); 198 199 starttime = time_second; 200 201 /* 202 * Push files whose dirty time has expired. Be careful 203 * of interrupt race on slp queue. 204 */ 205 crit_enter(); 206 slp = &syncer_workitem_pending[syncer_delayno]; 207 syncer_delayno += 1; 208 if (syncer_delayno == syncer_maxdelay) 209 syncer_delayno = 0; 210 crit_exit(); 211 212 while ((vp = LIST_FIRST(slp)) != NULL) { 213 if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 214 VOP_FSYNC(vp, MNT_LAZY, td); 215 vput(vp); 216 } 217 crit_enter(); 218 219 /* 220 * If the vnode is still at the head of the list 221 * we were not able to completely flush it. To 222 * give other vnodes a fair shake we move it to 223 * a later slot. 224 * 225 * Note that v_tag VT_VFS vnodes can remain on the 226 * worklist with no dirty blocks, but sync_fsync() 227 * moves it to a later slot so we will never see it 228 * here. 229 */ 230 if (LIST_FIRST(slp) == vp) { 231 if (RB_EMPTY(&vp->v_rbdirty_tree) && 232 !vn_isdisk(vp, NULL)) { 233 panic("sched_sync: fsync failed vp %p tag %d", vp, vp->v_tag); 234 } 235 vn_syncer_add_to_worklist(vp, syncdelay); 236 } 237 crit_exit(); 238 } 239 240 /* 241 * Do soft update processing. 242 */ 243 if (bioops.io_sync) 244 (*bioops.io_sync)(NULL); 245 246 /* 247 * The variable rushjob allows the kernel to speed up the 248 * processing of the filesystem syncer process. A rushjob 249 * value of N tells the filesystem syncer to process the next 250 * N seconds worth of work on its queue ASAP. Currently rushjob 251 * is used by the soft update code to speed up the filesystem 252 * syncer process when the incore state is getting so far 253 * ahead of the disk that the kernel memory pool is being 254 * threatened with exhaustion. 255 */ 256 if (rushjob > 0) { 257 rushjob -= 1; 258 continue; 259 } 260 /* 261 * If it has taken us less than a second to process the 262 * current work, then wait. Otherwise start right over 263 * again. We can still lose time if any single round 264 * takes more than two seconds, but it does not really 265 * matter as we are just trying to generally pace the 266 * filesystem activity. 267 */ 268 if (time_second == starttime) 269 tsleep(&lbolt_syncer, 0, "syncer", 0); 270 } 271 } 272 273 /* 274 * Request the syncer daemon to speed up its work. 275 * We never push it to speed up more than half of its 276 * normal turn time, otherwise it could take over the cpu. 277 * 278 * YYY wchan field protected by the BGL. 279 */ 280 int 281 speedup_syncer(void) 282 { 283 /* 284 * Don't bother protecting the test. unsleep_and_wakeup_thread() 285 * will only do something real if the thread is in the right state. 286 */ 287 wakeup(&lbolt_syncer); 288 if (rushjob < syncdelay / 2) { 289 rushjob += 1; 290 stat_rush_requests += 1; 291 return (1); 292 } 293 return(0); 294 } 295 296 /* 297 * Routine to create and manage a filesystem syncer vnode. 298 */ 299 #define sync_close ((int (*) (struct vop_close_args *))nullop) 300 static int sync_fsync (struct vop_fsync_args *); 301 static int sync_inactive (struct vop_inactive_args *); 302 static int sync_reclaim (struct vop_reclaim_args *); 303 #define sync_lock ((int (*) (struct vop_lock_args *))vop_stdlock) 304 #define sync_unlock ((int (*) (struct vop_unlock_args *))vop_stdunlock) 305 static int sync_print (struct vop_print_args *); 306 #define sync_islocked ((int(*) (struct vop_islocked_args *))vop_stdislocked) 307 308 static struct vop_ops *sync_vnode_vops; 309 static struct vnodeopv_entry_desc sync_vnodeop_entries[] = { 310 { &vop_default_desc, vop_eopnotsupp }, 311 { &vop_close_desc, (void *) sync_close }, /* close */ 312 { &vop_fsync_desc, (void *) sync_fsync }, /* fsync */ 313 { &vop_inactive_desc, (void *) sync_inactive }, /* inactive */ 314 { &vop_reclaim_desc, (void *) sync_reclaim }, /* reclaim */ 315 { &vop_lock_desc, (void *) sync_lock }, /* lock */ 316 { &vop_unlock_desc, (void *) sync_unlock }, /* unlock */ 317 { &vop_print_desc, (void *) sync_print }, /* print */ 318 { &vop_islocked_desc, (void *) sync_islocked }, /* islocked */ 319 { NULL, NULL } 320 }; 321 322 static struct vnodeopv_desc sync_vnodeop_opv_desc = 323 { &sync_vnode_vops, sync_vnodeop_entries, 0 }; 324 325 VNODEOP_SET(sync_vnodeop_opv_desc); 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, &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 mp->mnt_syncer = vp; 367 vx_unlock(vp); 368 return (0); 369 } 370 371 /* 372 * Do a lazy sync of the filesystem. 373 * 374 * sync_fsync { struct vnode *a_vp, struct ucred *a_cred, int a_waitfor, 375 * struct thread *a_td } 376 */ 377 static int 378 sync_fsync(struct vop_fsync_args *ap) 379 { 380 struct vnode *syncvp = ap->a_vp; 381 struct mount *mp = syncvp->v_mount; 382 struct thread *td = ap->a_td; 383 int asyncflag; 384 385 /* 386 * We only need to do something if this is a lazy evaluation. 387 */ 388 if (ap->a_waitfor != MNT_LAZY) 389 return (0); 390 391 /* 392 * Move ourselves to the back of the sync list. 393 */ 394 vn_syncer_add_to_worklist(syncvp, syncdelay); 395 396 /* 397 * Walk the list of vnodes pushing all that are dirty and 398 * not already on the sync list, and freeing vnodes which have 399 * no refs and whos VM objects are empty. vfs_msync() handles 400 * the VM issues and must be called whether the mount is readonly 401 * or not. 402 */ 403 if (vfs_busy(mp, LK_NOWAIT, td) != 0) 404 return (0); 405 if (mp->mnt_flag & MNT_RDONLY) { 406 vfs_msync(mp, MNT_NOWAIT); 407 } else { 408 asyncflag = mp->mnt_flag & MNT_ASYNC; 409 mp->mnt_flag &= ~MNT_ASYNC; /* ZZZ hack */ 410 vfs_msync(mp, MNT_NOWAIT); 411 VFS_SYNC(mp, MNT_LAZY, td); 412 if (asyncflag) 413 mp->mnt_flag |= MNT_ASYNC; 414 } 415 vfs_unbusy(mp, td); 416 return (0); 417 } 418 419 /* 420 * The syncer vnode is no referenced. 421 * 422 * sync_inactive { struct vnode *a_vp, struct proc *a_p } 423 */ 424 static int 425 sync_inactive(struct vop_inactive_args *ap) 426 { 427 vgone(ap->a_vp); 428 return (0); 429 } 430 431 /* 432 * The syncer vnode is no longer needed and is being decommissioned. 433 * 434 * Modifications to the worklist must be protected with a critical 435 * section. 436 * 437 * sync_reclaim { struct vnode *a_vp } 438 */ 439 static int 440 sync_reclaim(struct vop_reclaim_args *ap) 441 { 442 struct vnode *vp = ap->a_vp; 443 444 crit_enter(); 445 vp->v_mount->mnt_syncer = NULL; 446 if (vp->v_flag & VONWORKLST) { 447 LIST_REMOVE(vp, v_synclist); 448 vp->v_flag &= ~VONWORKLST; 449 } 450 crit_exit(); 451 452 return (0); 453 } 454 455 /* 456 * Print out a syncer vnode. 457 * 458 * sync_print { struct vnode *a_vp } 459 */ 460 static int 461 sync_print(struct vop_print_args *ap) 462 { 463 struct vnode *vp = ap->a_vp; 464 465 printf("syncer vnode"); 466 lockmgr_printinfo(&vp->v_lock); 467 printf("\n"); 468 return (0); 469 } 470 471