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 1.17 2007/11/06 03:49:58 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) == 0) { 214 VOP_FSYNC(vp, MNT_LAZY); 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 sync processing for each mount. 242 */ 243 bio_ops_sync(NULL); 244 245 /* 246 * The variable rushjob allows the kernel to speed up the 247 * processing of the filesystem syncer process. A rushjob 248 * value of N tells the filesystem syncer to process the next 249 * N seconds worth of work on its queue ASAP. Currently rushjob 250 * is used by the soft update code to speed up the filesystem 251 * syncer process when the incore state is getting so far 252 * ahead of the disk that the kernel memory pool is being 253 * threatened with exhaustion. 254 */ 255 if (rushjob > 0) { 256 rushjob -= 1; 257 continue; 258 } 259 /* 260 * If it has taken us less than a second to process the 261 * current work, then wait. Otherwise start right over 262 * again. We can still lose time if any single round 263 * takes more than two seconds, but it does not really 264 * matter as we are just trying to generally pace the 265 * filesystem activity. 266 */ 267 if (time_second == starttime) 268 tsleep(&lbolt_syncer, 0, "syncer", 0); 269 } 270 } 271 272 /* 273 * Request the syncer daemon to speed up its work. 274 * We never push it to speed up more than half of its 275 * normal turn time, otherwise it could take over the cpu. 276 * 277 * YYY wchan field protected by the BGL. 278 */ 279 int 280 speedup_syncer(void) 281 { 282 /* 283 * Don't bother protecting the test. unsleep_and_wakeup_thread() 284 * will only do something real if the thread is in the right state. 285 */ 286 wakeup(&lbolt_syncer); 287 if (rushjob < syncdelay / 2) { 288 rushjob += 1; 289 stat_rush_requests += 1; 290 return (1); 291 } 292 return(0); 293 } 294 295 /* 296 * Routine to create and manage a filesystem syncer vnode. 297 */ 298 static int sync_close(struct vop_close_args *); 299 static int sync_fsync(struct vop_fsync_args *); 300 static int sync_inactive(struct vop_inactive_args *); 301 static int sync_reclaim (struct vop_reclaim_args *); 302 static int sync_print(struct vop_print_args *); 303 304 static struct vop_ops sync_vnode_vops = { 305 .vop_default = vop_eopnotsupp, 306 .vop_close = sync_close, 307 .vop_fsync = sync_fsync, 308 .vop_inactive = sync_inactive, 309 .vop_reclaim = sync_reclaim, 310 .vop_print = sync_print, 311 }; 312 313 static struct vop_ops *sync_vnode_vops_p = &sync_vnode_vops; 314 315 VNODEOP_SET(sync_vnode_vops); 316 317 /* 318 * Create a new filesystem syncer vnode for the specified mount point. 319 * This vnode is placed on the worklist and is responsible for sync'ing 320 * the filesystem. 321 * 322 * NOTE: read-only mounts are also placed on the worklist. The filesystem 323 * sync code is also responsible for cleaning up vnodes. 324 */ 325 int 326 vfs_allocate_syncvnode(struct mount *mp) 327 { 328 struct vnode *vp; 329 static long start, incr, next; 330 int error; 331 332 /* Allocate a new vnode */ 333 error = getspecialvnode(VT_VFS, mp, &sync_vnode_vops_p, &vp, 0, 0); 334 if (error) { 335 mp->mnt_syncer = NULL; 336 return (error); 337 } 338 vp->v_type = VNON; 339 /* 340 * Place the vnode onto the syncer worklist. We attempt to 341 * scatter them about on the list so that they will go off 342 * at evenly distributed times even if all the filesystems 343 * are mounted at once. 344 */ 345 next += incr; 346 if (next == 0 || next > syncer_maxdelay) { 347 start /= 2; 348 incr /= 2; 349 if (start == 0) { 350 start = syncer_maxdelay / 2; 351 incr = syncer_maxdelay; 352 } 353 next = start; 354 } 355 vn_syncer_add_to_worklist(vp, syncdelay > 0 ? next % syncdelay : 0); 356 mp->mnt_syncer = vp; 357 vx_unlock(vp); 358 return (0); 359 } 360 361 static int 362 sync_close(struct vop_close_args *ap) 363 { 364 return (0); 365 } 366 367 /* 368 * Do a lazy sync of the filesystem. 369 * 370 * sync_fsync { struct vnode *a_vp, int a_waitfor } 371 */ 372 static int 373 sync_fsync(struct vop_fsync_args *ap) 374 { 375 struct vnode *syncvp = ap->a_vp; 376 struct mount *mp = syncvp->v_mount; 377 int asyncflag; 378 379 /* 380 * We only need to do something if this is a lazy evaluation. 381 */ 382 if (ap->a_waitfor != MNT_LAZY) 383 return (0); 384 385 /* 386 * Move ourselves to the back of the sync list. 387 */ 388 vn_syncer_add_to_worklist(syncvp, syncdelay); 389 390 /* 391 * Walk the list of vnodes pushing all that are dirty and 392 * not already on the sync list, and freeing vnodes which have 393 * no refs and whos VM objects are empty. vfs_msync() handles 394 * the VM issues and must be called whether the mount is readonly 395 * or not. 396 */ 397 if (vfs_busy(mp, LK_NOWAIT) != 0) 398 return (0); 399 if (mp->mnt_flag & MNT_RDONLY) { 400 vfs_msync(mp, MNT_NOWAIT); 401 } else { 402 asyncflag = mp->mnt_flag & MNT_ASYNC; 403 mp->mnt_flag &= ~MNT_ASYNC; /* ZZZ hack */ 404 vfs_msync(mp, MNT_NOWAIT); 405 VFS_SYNC(mp, MNT_LAZY); 406 if (asyncflag) 407 mp->mnt_flag |= MNT_ASYNC; 408 } 409 vfs_unbusy(mp); 410 return (0); 411 } 412 413 /* 414 * The syncer vnode is no longer referenced. 415 * 416 * sync_inactive { struct vnode *a_vp, struct proc *a_p } 417 */ 418 static int 419 sync_inactive(struct vop_inactive_args *ap) 420 { 421 vgone_vxlocked(ap->a_vp); 422 return (0); 423 } 424 425 /* 426 * The syncer vnode is no longer needed and is being decommissioned. 427 * 428 * Modifications to the worklist must be protected with a critical 429 * section. 430 * 431 * sync_reclaim { struct vnode *a_vp } 432 */ 433 static int 434 sync_reclaim(struct vop_reclaim_args *ap) 435 { 436 struct vnode *vp = ap->a_vp; 437 438 crit_enter(); 439 vp->v_mount->mnt_syncer = NULL; 440 if (vp->v_flag & VONWORKLST) { 441 LIST_REMOVE(vp, v_synclist); 442 vp->v_flag &= ~VONWORKLST; 443 } 444 crit_exit(); 445 446 return (0); 447 } 448 449 /* 450 * Print out a syncer vnode. 451 * 452 * sync_print { struct vnode *a_vp } 453 */ 454 static int 455 sync_print(struct vop_print_args *ap) 456 { 457 struct vnode *vp = ap->a_vp; 458 459 kprintf("syncer vnode"); 460 lockmgr_printinfo(&vp->v_lock); 461 kprintf("\n"); 462 return (0); 463 } 464 465