1 /* $OpenBSD: vfs_sync.c,v 1.32 2005/05/31 11:35:33 art Exp $ */ 2 3 /* 4 * Portions of this code are: 5 * 6 * Copyright (c) 1989, 1993 7 * The Regents of the University of California. All rights reserved. 8 * (c) UNIX System Laboratories, Inc. 9 * All or some portions of this file are derived from material licensed 10 * to the University of California by American Telephone and Telegraph 11 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 12 * the permission of UNIX System Laboratories, Inc. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. 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 39 /* 40 * Syncer daemon 41 */ 42 43 #include <sys/queue.h> 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/proc.h> 47 #include <sys/mount.h> 48 #include <sys/vnode.h> 49 #include <sys/buf.h> 50 #include <sys/malloc.h> 51 52 #include <sys/kernel.h> 53 #include <sys/sched.h> 54 55 #ifdef FFS_SOFTUPDATES 56 int softdep_process_worklist(struct mount *); 57 #endif 58 59 /* 60 * The workitem queue. 61 */ 62 #define SYNCER_MAXDELAY 32 /* maximum sync delay time */ 63 #define SYNCER_DEFAULT 30 /* default sync delay time */ 64 int syncer_maxdelay = SYNCER_MAXDELAY; /* maximum delay time */ 65 time_t syncdelay = SYNCER_DEFAULT; /* time to delay syncing vnodes */ 66 67 int rushjob = 0; /* number of slots to run ASAP */ 68 int stat_rush_requests = 0; /* number of rush requests */ 69 70 static int syncer_delayno = 0; 71 static long syncer_mask; 72 LIST_HEAD(synclist, vnode); 73 static struct synclist *syncer_workitem_pending; 74 75 struct proc *syncerproc; 76 77 /* 78 * The workitem queue. 79 * 80 * It is useful to delay writes of file data and filesystem metadata 81 * for tens of seconds so that quickly created and deleted files need 82 * not waste disk bandwidth being created and removed. To realize this, 83 * we append vnodes to a "workitem" queue. When running with a soft 84 * updates implementation, most pending metadata dependencies should 85 * not wait for more than a few seconds. Thus, mounted on block devices 86 * are delayed only about a half the time that file data is delayed. 87 * Similarly, directory updates are more critical, so are only delayed 88 * about a third the time that file data is delayed. Thus, there are 89 * SYNCER_MAXDELAY queues that are processed round-robin at a rate of 90 * one each second (driven off the filesystem syncer process). The 91 * syncer_delayno variable indicates the next queue that is to be processed. 92 * Items that need to be processed soon are placed in this queue: 93 * 94 * syncer_workitem_pending[syncer_delayno] 95 * 96 * A delay of fifteen seconds is done by placing the request fifteen 97 * entries later in the queue: 98 * 99 * syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask] 100 * 101 */ 102 103 void 104 vn_initialize_syncerd() 105 106 { 107 syncer_workitem_pending = hashinit(syncer_maxdelay, M_VNODE, M_WAITOK, 108 &syncer_mask); 109 syncer_maxdelay = syncer_mask + 1; 110 } 111 112 /* 113 * Add an item to the syncer work queue. 114 */ 115 void 116 vn_syncer_add_to_worklist(vp, delay) 117 struct vnode *vp; 118 int delay; 119 { 120 int s, slot; 121 122 if (delay > syncer_maxdelay - 2) 123 delay = syncer_maxdelay - 2; 124 slot = (syncer_delayno + delay) & syncer_mask; 125 126 s = splbio(); 127 if (vp->v_bioflag & VBIOONSYNCLIST) 128 LIST_REMOVE(vp, v_synclist); 129 130 vp->v_bioflag |= VBIOONSYNCLIST; 131 LIST_INSERT_HEAD(&syncer_workitem_pending[slot], vp, v_synclist); 132 splx(s); 133 } 134 135 /* 136 * System filesystem synchronizer daemon. 137 */ 138 139 void 140 sched_sync(p) 141 struct proc *p; 142 { 143 struct synclist *slp; 144 struct vnode *vp; 145 long starttime; 146 int s; 147 148 syncerproc = curproc; 149 150 for (;;) { 151 starttime = time_second; 152 153 /* 154 * Push files whose dirty time has expired. 155 */ 156 s = splbio(); 157 slp = &syncer_workitem_pending[syncer_delayno]; 158 159 syncer_delayno += 1; 160 if (syncer_delayno == syncer_maxdelay) 161 syncer_delayno = 0; 162 163 while ((vp = LIST_FIRST(slp)) != NULL) { 164 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, p) != 0) { 165 /* 166 * If we fail to get the lock, we move this 167 * vnode one second ahead in time. 168 * XXX - no good, but the best we can do. 169 */ 170 vn_syncer_add_to_worklist(vp, 1); 171 continue; 172 } 173 splx(s); 174 (void) VOP_FSYNC(vp, p->p_ucred, MNT_LAZY, p); 175 VOP_UNLOCK(vp, 0, p); 176 s = splbio(); 177 if (LIST_FIRST(slp) == vp) { 178 /* 179 * Note: disk vps can remain on the 180 * worklist too with no dirty blocks, but 181 * since sync_fsync() moves it to a different 182 * slot we are safe. 183 */ 184 if (LIST_FIRST(&vp->v_dirtyblkhd) == NULL && 185 vp->v_type != VBLK) { 186 vprint("fsync failed", vp); 187 if (vp->v_mount != NULL) 188 printf("mounted on: %s\n", 189 vp->v_mount->mnt_stat.f_mntonname); 190 panic("sched_sync: fsync failed"); 191 } 192 /* 193 * Put us back on the worklist. The worklist 194 * routine will remove us from our current 195 * position and then add us back in at a later 196 * position. 197 */ 198 vn_syncer_add_to_worklist(vp, syncdelay); 199 } 200 } 201 202 splx(s); 203 204 #ifdef FFS_SOFTUPDATES 205 /* 206 * Do soft update processing. 207 */ 208 softdep_process_worklist(NULL); 209 #endif 210 211 /* 212 * The variable rushjob allows the kernel to speed up the 213 * processing of the filesystem syncer process. A rushjob 214 * value of N tells the filesystem syncer to process the next 215 * N seconds worth of work on its queue ASAP. Currently rushjob 216 * is used by the soft update code to speed up the filesystem 217 * syncer process when the incore state is getting so far 218 * ahead of the disk that the kernel memory pool is being 219 * threatened with exhaustion. 220 */ 221 if (rushjob > 0) { 222 rushjob -= 1; 223 continue; 224 } 225 /* 226 * If it has taken us less than a second to process the 227 * current work, then wait. Otherwise start right over 228 * again. We can still lose time if any single round 229 * takes more than two seconds, but it does not really 230 * matter as we are just trying to generally pace the 231 * filesystem activity. 232 */ 233 if (time_second == starttime) 234 tsleep(&lbolt, PPAUSE, "syncer", 0); 235 } 236 } 237 238 /* 239 * Request the syncer daemon to speed up its work. 240 * We never push it to speed up more than half of its 241 * normal turn time, otherwise it could take over the cpu. 242 */ 243 int 244 speedup_syncer() 245 { 246 int s; 247 248 SCHED_LOCK(s); 249 if (syncerproc && syncerproc->p_wchan == &lbolt) 250 setrunnable(syncerproc); 251 SCHED_UNLOCK(s); 252 if (rushjob < syncdelay / 2) { 253 rushjob += 1; 254 stat_rush_requests += 1; 255 return 1; 256 } 257 return 0; 258 } 259 260 /* 261 * Routine to create and manage a filesystem syncer vnode. 262 */ 263 #define sync_close nullop 264 int sync_fsync(void *); 265 int sync_inactive(void *); 266 #define sync_reclaim nullop 267 #define sync_lock vop_generic_lock 268 #define sync_unlock vop_generic_unlock 269 int sync_print(void *); 270 #define sync_islocked vop_generic_islocked 271 272 int (**sync_vnodeop_p)(void *); 273 struct vnodeopv_entry_desc sync_vnodeop_entries[] = { 274 { &vop_default_desc, vn_default_error }, 275 { &vop_close_desc, sync_close }, /* close */ 276 { &vop_fsync_desc, sync_fsync }, /* fsync */ 277 { &vop_inactive_desc, sync_inactive }, /* inactive */ 278 { &vop_reclaim_desc, sync_reclaim }, /* reclaim */ 279 { &vop_lock_desc, sync_lock }, /* lock */ 280 { &vop_unlock_desc, sync_unlock }, /* unlock */ 281 { &vop_print_desc, sync_print }, /* print */ 282 { &vop_islocked_desc, sync_islocked }, /* islocked */ 283 { (struct vnodeop_desc*)NULL, (int(*)(void *))NULL } 284 }; 285 struct vnodeopv_desc sync_vnodeop_opv_desc = { 286 &sync_vnodeop_p, sync_vnodeop_entries 287 }; 288 289 /* 290 * Create a new filesystem syncer vnode for the specified mount point. 291 */ 292 int 293 vfs_allocate_syncvnode(mp) 294 struct mount *mp; 295 { 296 struct vnode *vp; 297 static long start, incr, next; 298 int error; 299 300 /* Allocate a new vnode */ 301 if ((error = getnewvnode(VT_VFS, mp, sync_vnodeop_p, &vp)) != 0) { 302 mp->mnt_syncer = NULL; 303 return (error); 304 } 305 vp->v_writecount = 1; 306 vp->v_type = VNON; 307 /* 308 * Place the vnode onto the syncer worklist. We attempt to 309 * scatter them about on the list so that they will go off 310 * at evenly distributed times even if all the filesystems 311 * are mounted at once. 312 */ 313 next += incr; 314 if (next == 0 || next > syncer_maxdelay) { 315 start /= 2; 316 incr /= 2; 317 if (start == 0) { 318 start = syncer_maxdelay / 2; 319 incr = syncer_maxdelay; 320 } 321 next = start; 322 } 323 vn_syncer_add_to_worklist(vp, next); 324 mp->mnt_syncer = vp; 325 return (0); 326 } 327 328 /* 329 * Do a lazy sync of the filesystem. 330 */ 331 int 332 sync_fsync(v) 333 void *v; 334 { 335 struct vop_fsync_args /* { 336 struct vnodeop_desc *a_desc; 337 struct vnode *a_vp; 338 struct ucred *a_cred; 339 int a_waitfor; 340 struct proc *a_p; 341 } */ *ap = v; 342 struct vnode *syncvp = ap->a_vp; 343 struct mount *mp = syncvp->v_mount; 344 int asyncflag; 345 346 /* 347 * We only need to do something if this is a lazy evaluation. 348 */ 349 if (ap->a_waitfor != MNT_LAZY) 350 return (0); 351 352 /* 353 * Move ourselves to the back of the sync list. 354 */ 355 vn_syncer_add_to_worklist(syncvp, syncdelay); 356 357 /* 358 * Walk the list of vnodes pushing all that are dirty and 359 * not already on the sync list. 360 */ 361 simple_lock(&mountlist_slock); 362 if (vfs_busy(mp, LK_NOWAIT, &mountlist_slock, ap->a_p) == 0) { 363 asyncflag = mp->mnt_flag & MNT_ASYNC; 364 mp->mnt_flag &= ~MNT_ASYNC; 365 VFS_SYNC(mp, MNT_LAZY, ap->a_cred, ap->a_p); 366 if (asyncflag) 367 mp->mnt_flag |= MNT_ASYNC; 368 vfs_unbusy(mp, ap->a_p); 369 } else 370 simple_unlock(&mountlist_slock); 371 372 return (0); 373 } 374 375 /* 376 * The syncer vnode is no longer needed and is being decommissioned. 377 */ 378 int 379 sync_inactive(v) 380 void *v; 381 { 382 struct vop_inactive_args /* { 383 struct vnodeop_desc *a_desc; 384 struct vnode *a_vp; 385 struct proc *a_p; 386 } */ *ap = v; 387 388 struct vnode *vp = ap->a_vp; 389 int s; 390 391 if (vp->v_usecount == 0) { 392 VOP_UNLOCK(vp, 0, ap->a_p); 393 return (0); 394 } 395 396 vp->v_mount->mnt_syncer = NULL; 397 398 s = splbio(); 399 400 LIST_REMOVE(vp, v_synclist); 401 vp->v_bioflag &= ~VBIOONSYNCLIST; 402 403 splx(s); 404 405 vp->v_writecount = 0; 406 vput(vp); 407 408 return (0); 409 } 410 411 /* 412 * Print out a syncer vnode. 413 */ 414 int 415 sync_print(v) 416 void *v; 417 418 { 419 struct vop_print_args /* { 420 struct vnodeop_desc *a_desc; 421 struct vnode *a_vp; 422 } */ *ap = v; 423 struct vnode *vp = ap->a_vp; 424 425 printf("syncer vnode"); 426 if (vp->v_vnlock != NULL) 427 lockmgr_printinfo(vp->v_vnlock); 428 printf("\n"); 429 return (0); 430 } 431