1 /* $OpenBSD: vfs_sync.c,v 1.35 2005/11/06 13:07:48 pedro 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(void) 105 { 106 syncer_workitem_pending = hashinit(syncer_maxdelay, M_VNODE, M_WAITOK, 107 &syncer_mask); 108 syncer_maxdelay = syncer_mask + 1; 109 } 110 111 /* 112 * Add an item to the syncer work queue. 113 */ 114 void 115 vn_syncer_add_to_worklist(struct vnode *vp, int delay) 116 { 117 int s, slot; 118 119 if (delay > syncer_maxdelay - 2) 120 delay = syncer_maxdelay - 2; 121 slot = (syncer_delayno + delay) & syncer_mask; 122 123 s = splbio(); 124 if (vp->v_bioflag & VBIOONSYNCLIST) 125 LIST_REMOVE(vp, v_synclist); 126 127 vp->v_bioflag |= VBIOONSYNCLIST; 128 LIST_INSERT_HEAD(&syncer_workitem_pending[slot], vp, v_synclist); 129 splx(s); 130 } 131 132 /* 133 * System filesystem synchronizer daemon. 134 */ 135 void 136 sched_sync(struct proc *p) 137 { 138 struct synclist *slp; 139 struct vnode *vp; 140 long starttime; 141 int s; 142 143 syncerproc = curproc; 144 145 for (;;) { 146 starttime = time_second; 147 148 /* 149 * Push files whose dirty time has expired. 150 */ 151 s = splbio(); 152 slp = &syncer_workitem_pending[syncer_delayno]; 153 154 syncer_delayno += 1; 155 if (syncer_delayno == syncer_maxdelay) 156 syncer_delayno = 0; 157 158 while ((vp = LIST_FIRST(slp)) != NULL) { 159 if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT, p)) { 160 /* 161 * If we fail to get the lock, we move this 162 * vnode one second ahead in time. 163 * XXX - no good, but the best we can do. 164 */ 165 vn_syncer_add_to_worklist(vp, 1); 166 continue; 167 } 168 splx(s); 169 (void) VOP_FSYNC(vp, p->p_ucred, MNT_LAZY, p); 170 vput(vp); 171 s = splbio(); 172 if (LIST_FIRST(slp) == vp) { 173 /* 174 * Note: disk vps can remain on the 175 * worklist too with no dirty blocks, but 176 * since sync_fsync() moves it to a different 177 * slot we are safe. 178 */ 179 if (LIST_FIRST(&vp->v_dirtyblkhd) == NULL && 180 vp->v_type != VBLK) { 181 vprint("fsync failed", vp); 182 if (vp->v_mount != NULL) 183 printf("mounted on: %s\n", 184 vp->v_mount->mnt_stat.f_mntonname); 185 panic("sched_sync: fsync failed"); 186 } 187 /* 188 * Put us back on the worklist. The worklist 189 * routine will remove us from our current 190 * position and then add us back in at a later 191 * position. 192 */ 193 vn_syncer_add_to_worklist(vp, syncdelay); 194 } 195 } 196 197 splx(s); 198 199 #ifdef FFS_SOFTUPDATES 200 /* 201 * Do soft update processing. 202 */ 203 softdep_process_worklist(NULL); 204 #endif 205 206 /* 207 * The variable rushjob allows the kernel to speed up the 208 * processing of the filesystem syncer process. A rushjob 209 * value of N tells the filesystem syncer to process the next 210 * N seconds worth of work on its queue ASAP. Currently rushjob 211 * is used by the soft update code to speed up the filesystem 212 * syncer process when the incore state is getting so far 213 * ahead of the disk that the kernel memory pool is being 214 * threatened with exhaustion. 215 */ 216 if (rushjob > 0) { 217 rushjob -= 1; 218 continue; 219 } 220 /* 221 * If it has taken us less than a second to process the 222 * current work, then wait. Otherwise start right over 223 * again. We can still lose time if any single round 224 * takes more than two seconds, but it does not really 225 * matter as we are just trying to generally pace the 226 * filesystem activity. 227 */ 228 if (time_second == starttime) 229 tsleep(&lbolt, PPAUSE, "syncer", 0); 230 } 231 } 232 233 /* 234 * Request the syncer daemon to speed up its work. 235 * We never push it to speed up more than half of its 236 * normal turn time, otherwise it could take over the cpu. 237 */ 238 int 239 speedup_syncer(void) 240 { 241 int s; 242 243 SCHED_LOCK(s); 244 if (syncerproc && syncerproc->p_wchan == &lbolt) 245 setrunnable(syncerproc); 246 SCHED_UNLOCK(s); 247 if (rushjob < syncdelay / 2) { 248 rushjob += 1; 249 stat_rush_requests += 1; 250 return 1; 251 } 252 return 0; 253 } 254 255 /* 256 * Routine to create and manage a filesystem syncer vnode. 257 */ 258 #define sync_close nullop 259 int sync_fsync(void *); 260 int sync_inactive(void *); 261 #define sync_reclaim nullop 262 #define sync_lock vop_generic_lock 263 #define sync_unlock vop_generic_unlock 264 int sync_print(void *); 265 #define sync_islocked vop_generic_islocked 266 267 int (**sync_vnodeop_p)(void *); 268 struct vnodeopv_entry_desc sync_vnodeop_entries[] = { 269 { &vop_default_desc, vn_default_error }, 270 { &vop_close_desc, sync_close }, /* close */ 271 { &vop_fsync_desc, sync_fsync }, /* fsync */ 272 { &vop_inactive_desc, sync_inactive }, /* inactive */ 273 { &vop_reclaim_desc, sync_reclaim }, /* reclaim */ 274 { &vop_lock_desc, sync_lock }, /* lock */ 275 { &vop_unlock_desc, sync_unlock }, /* unlock */ 276 { &vop_print_desc, sync_print }, /* print */ 277 { &vop_islocked_desc, sync_islocked }, /* islocked */ 278 { (struct vnodeop_desc*)NULL, (int(*)(void *))NULL } 279 }; 280 struct vnodeopv_desc sync_vnodeop_opv_desc = { 281 &sync_vnodeop_p, sync_vnodeop_entries 282 }; 283 284 /* 285 * Create a new filesystem syncer vnode for the specified mount point. 286 */ 287 int 288 vfs_allocate_syncvnode(struct mount *mp) 289 { 290 struct vnode *vp; 291 static long start, incr, next; 292 int error; 293 294 /* Allocate a new vnode */ 295 if ((error = getnewvnode(VT_VFS, mp, sync_vnodeop_p, &vp)) != 0) { 296 mp->mnt_syncer = NULL; 297 return (error); 298 } 299 vp->v_writecount = 1; 300 vp->v_type = VNON; 301 /* 302 * Place the vnode onto the syncer worklist. We attempt to 303 * scatter them about on the list so that they will go off 304 * at evenly distributed times even if all the filesystems 305 * are mounted at once. 306 */ 307 next += incr; 308 if (next == 0 || next > syncer_maxdelay) { 309 start /= 2; 310 incr /= 2; 311 if (start == 0) { 312 start = syncer_maxdelay / 2; 313 incr = syncer_maxdelay; 314 } 315 next = start; 316 } 317 vn_syncer_add_to_worklist(vp, next); 318 mp->mnt_syncer = vp; 319 return (0); 320 } 321 322 /* 323 * Do a lazy sync of the filesystem. 324 */ 325 int 326 sync_fsync(void *v) 327 { 328 struct vop_fsync_args /* { 329 struct vnodeop_desc *a_desc; 330 struct vnode *a_vp; 331 struct ucred *a_cred; 332 int a_waitfor; 333 struct proc *a_p; 334 } */ *ap = v; 335 struct vnode *syncvp = ap->a_vp; 336 struct mount *mp = syncvp->v_mount; 337 int asyncflag; 338 339 /* 340 * We only need to do something if this is a lazy evaluation. 341 */ 342 if (ap->a_waitfor != MNT_LAZY) 343 return (0); 344 345 /* 346 * Move ourselves to the back of the sync list. 347 */ 348 vn_syncer_add_to_worklist(syncvp, syncdelay); 349 350 /* 351 * Walk the list of vnodes pushing all that are dirty and 352 * not already on the sync list. 353 */ 354 simple_lock(&mountlist_slock); 355 if (vfs_busy(mp, LK_NOWAIT, &mountlist_slock, ap->a_p) == 0) { 356 asyncflag = mp->mnt_flag & MNT_ASYNC; 357 mp->mnt_flag &= ~MNT_ASYNC; 358 VFS_SYNC(mp, MNT_LAZY, ap->a_cred, ap->a_p); 359 if (asyncflag) 360 mp->mnt_flag |= MNT_ASYNC; 361 vfs_unbusy(mp, ap->a_p); 362 } else 363 simple_unlock(&mountlist_slock); 364 365 return (0); 366 } 367 368 /* 369 * The syncer vnode is no longer needed and is being decommissioned. 370 */ 371 int 372 sync_inactive(void *v) 373 { 374 struct vop_inactive_args /* { 375 struct vnodeop_desc *a_desc; 376 struct vnode *a_vp; 377 struct proc *a_p; 378 } */ *ap = v; 379 380 struct vnode *vp = ap->a_vp; 381 int s; 382 383 if (vp->v_usecount == 0) { 384 VOP_UNLOCK(vp, 0, ap->a_p); 385 return (0); 386 } 387 388 vp->v_mount->mnt_syncer = NULL; 389 390 s = splbio(); 391 392 LIST_REMOVE(vp, v_synclist); 393 vp->v_bioflag &= ~VBIOONSYNCLIST; 394 395 splx(s); 396 397 vp->v_writecount = 0; 398 vput(vp); 399 400 return (0); 401 } 402 403 /* 404 * Print out a syncer vnode. 405 */ 406 int 407 sync_print(void *v) 408 { 409 printf("syncer vnode\n"); 410 411 return (0); 412 } 413