1 /* $OpenBSD: uvm_vnode.c,v 1.43 2006/07/31 11:51:29 mickey Exp $ */ 2 /* $NetBSD: uvm_vnode.c,v 1.36 2000/11/24 20:34:01 chs Exp $ */ 3 4 /* 5 * Copyright (c) 1997 Charles D. Cranor and Washington University. 6 * Copyright (c) 1991, 1993 7 * The Regents of the University of California. 8 * Copyright (c) 1990 University of Utah. 9 * 10 * All rights reserved. 11 * 12 * This code is derived from software contributed to Berkeley by 13 * the Systems Programming Group of the University of Utah Computer 14 * Science Department. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 3. All advertising materials mentioning features or use of this software 25 * must display the following acknowledgement: 26 * This product includes software developed by Charles D. Cranor, 27 * Washington University, the University of California, Berkeley and 28 * its contributors. 29 * 4. Neither the name of the University nor the names of its contributors 30 * may be used to endorse or promote products derived from this software 31 * without specific prior written permission. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 34 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 35 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 36 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 37 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 38 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 39 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 40 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 41 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 42 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 43 * SUCH DAMAGE. 44 * 45 * @(#)vnode_pager.c 8.8 (Berkeley) 2/13/94 46 * from: Id: uvm_vnode.c,v 1.1.2.26 1998/02/02 20:38:07 chuck Exp 47 */ 48 49 /* 50 * uvm_vnode.c: the vnode pager. 51 */ 52 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/proc.h> 56 #include <sys/malloc.h> 57 #include <sys/vnode.h> 58 #include <sys/disklabel.h> 59 #include <sys/ioctl.h> 60 #include <sys/fcntl.h> 61 #include <sys/conf.h> 62 #include <sys/rwlock.h> 63 64 #include <miscfs/specfs/specdev.h> 65 66 #include <uvm/uvm.h> 67 #include <uvm/uvm_vnode.h> 68 69 /* 70 * private global data structure 71 * 72 * we keep a list of writeable active vnode-backed VM objects for sync op. 73 * we keep a simpleq of vnodes that are currently being sync'd. 74 */ 75 76 LIST_HEAD(uvn_list_struct, uvm_vnode); 77 static struct uvn_list_struct uvn_wlist; /* writeable uvns */ 78 static simple_lock_data_t uvn_wl_lock; /* locks uvn_wlist */ 79 80 SIMPLEQ_HEAD(uvn_sq_struct, uvm_vnode); 81 static struct uvn_sq_struct uvn_sync_q; /* sync'ing uvns */ 82 struct rwlock uvn_sync_lock; /* locks sync operation */ 83 84 /* 85 * functions 86 */ 87 88 static void uvn_cluster(struct uvm_object *, voff_t, 89 voff_t *, voff_t *); 90 static void uvn_detach(struct uvm_object *); 91 static boolean_t uvn_flush(struct uvm_object *, voff_t, 92 voff_t, int); 93 static int uvn_get(struct uvm_object *, voff_t, 94 vm_page_t *, int *, int, 95 vm_prot_t, int, int); 96 static void uvn_init(void); 97 static int uvn_io(struct uvm_vnode *, vm_page_t *, 98 int, int, int); 99 static int uvn_put(struct uvm_object *, vm_page_t *, 100 int, boolean_t); 101 static void uvn_reference(struct uvm_object *); 102 static boolean_t uvn_releasepg(struct vm_page *, 103 struct vm_page **); 104 105 /* 106 * master pager structure 107 */ 108 109 struct uvm_pagerops uvm_vnodeops = { 110 uvn_init, 111 uvn_reference, 112 uvn_detach, 113 NULL, /* no specialized fault routine required */ 114 uvn_flush, 115 uvn_get, 116 uvn_put, 117 uvn_cluster, 118 uvm_mk_pcluster, /* use generic version of this: see uvm_pager.c */ 119 uvn_releasepg, 120 }; 121 122 /* 123 * the ops! 124 */ 125 126 /* 127 * uvn_init 128 * 129 * init pager private data structures. 130 */ 131 132 static void 133 uvn_init() 134 { 135 136 LIST_INIT(&uvn_wlist); 137 simple_lock_init(&uvn_wl_lock); 138 /* note: uvn_sync_q init'd in uvm_vnp_sync() */ 139 rw_init(&uvn_sync_lock, "uvnsync"); 140 } 141 142 /* 143 * uvn_attach 144 * 145 * attach a vnode structure to a VM object. if the vnode is already 146 * attached, then just bump the reference count by one and return the 147 * VM object. if not already attached, attach and return the new VM obj. 148 * the "accessprot" tells the max access the attaching thread wants to 149 * our pages. 150 * 151 * => caller must _not_ already be holding the lock on the uvm_object. 152 * => in fact, nothing should be locked so that we can sleep here. 153 * => note that uvm_object is first thing in vnode structure, so their 154 * pointers are equiv. 155 */ 156 157 struct uvm_object * 158 uvn_attach(arg, accessprot) 159 void *arg; 160 vm_prot_t accessprot; 161 { 162 struct vnode *vp = arg; 163 struct uvm_vnode *uvn = &vp->v_uvm; 164 struct vattr vattr; 165 int oldflags, result; 166 struct partinfo pi; 167 u_quad_t used_vnode_size; 168 UVMHIST_FUNC("uvn_attach"); UVMHIST_CALLED(maphist); 169 170 UVMHIST_LOG(maphist, "(vn=%p)", arg,0,0,0); 171 172 used_vnode_size = (u_quad_t)0; /* XXX gcc -Wuninitialized */ 173 174 /* 175 * first get a lock on the uvn. 176 */ 177 simple_lock(&uvn->u_obj.vmobjlock); 178 while (uvn->u_flags & UVM_VNODE_BLOCKED) { 179 printf("uvn_attach: blocked at %p flags 0x%x\n", 180 uvn, uvn->u_flags); 181 uvn->u_flags |= UVM_VNODE_WANTED; 182 UVMHIST_LOG(maphist, " SLEEPING on blocked vn",0,0,0,0); 183 UVM_UNLOCK_AND_WAIT(uvn, &uvn->u_obj.vmobjlock, FALSE, 184 "uvn_attach", 0); 185 simple_lock(&uvn->u_obj.vmobjlock); 186 UVMHIST_LOG(maphist," WOKE UP",0,0,0,0); 187 } 188 189 /* 190 * if we're mapping a BLK device, make sure it is a disk. 191 */ 192 if (vp->v_type == VBLK && bdevsw[major(vp->v_rdev)].d_type != D_DISK) { 193 simple_unlock(&uvn->u_obj.vmobjlock); /* drop lock */ 194 UVMHIST_LOG(maphist,"<- done (VBLK not D_DISK!)", 0,0,0,0); 195 return(NULL); 196 } 197 198 /* 199 * now we have lock and uvn must not be in a blocked state. 200 * first check to see if it is already active, in which case 201 * we can bump the reference count, check to see if we need to 202 * add it to the writeable list, and then return. 203 */ 204 if (uvn->u_flags & UVM_VNODE_VALID) { /* already active? */ 205 206 /* regain VREF if we were persisting */ 207 if (uvn->u_obj.uo_refs == 0) { 208 VREF(vp); 209 UVMHIST_LOG(maphist," VREF (reclaim persisting vnode)", 210 0,0,0,0); 211 } 212 uvn->u_obj.uo_refs++; /* bump uvn ref! */ 213 214 /* check for new writeable uvn */ 215 if ((accessprot & VM_PROT_WRITE) != 0 && 216 (uvn->u_flags & UVM_VNODE_WRITEABLE) == 0) { 217 simple_lock(&uvn_wl_lock); 218 LIST_INSERT_HEAD(&uvn_wlist, uvn, u_wlist); 219 simple_unlock(&uvn_wl_lock); 220 /* we are now on wlist! */ 221 uvn->u_flags |= UVM_VNODE_WRITEABLE; 222 } 223 224 /* unlock and return */ 225 simple_unlock(&uvn->u_obj.vmobjlock); 226 UVMHIST_LOG(maphist,"<- done, refcnt=%ld", uvn->u_obj.uo_refs, 227 0, 0, 0); 228 return (&uvn->u_obj); 229 } 230 231 /* 232 * need to call VOP_GETATTR() to get the attributes, but that could 233 * block (due to I/O), so we want to unlock the object before calling. 234 * however, we want to keep anyone else from playing with the object 235 * while it is unlocked. to do this we set UVM_VNODE_ALOCK which 236 * prevents anyone from attaching to the vnode until we are done with 237 * it. 238 */ 239 uvn->u_flags = UVM_VNODE_ALOCK; 240 simple_unlock(&uvn->u_obj.vmobjlock); /* drop lock in case we sleep */ 241 /* XXX: curproc? */ 242 243 if (vp->v_type == VBLK) { 244 /* 245 * We could implement this as a specfs getattr call, but: 246 * 247 * (1) VOP_GETATTR() would get the file system 248 * vnode operation, not the specfs operation. 249 * 250 * (2) All we want is the size, anyhow. 251 */ 252 result = (*bdevsw[major(vp->v_rdev)].d_ioctl)(vp->v_rdev, 253 DIOCGPART, (caddr_t)&pi, FREAD, curproc); 254 if (result == 0) { 255 /* XXX should remember blocksize */ 256 used_vnode_size = (u_quad_t)pi.disklab->d_secsize * 257 (u_quad_t)pi.part->p_size; 258 } 259 } else { 260 result = VOP_GETATTR(vp, &vattr, curproc->p_ucred, curproc); 261 if (result == 0) 262 used_vnode_size = vattr.va_size; 263 } 264 265 /* relock object */ 266 simple_lock(&uvn->u_obj.vmobjlock); 267 268 if (result != 0) { 269 if (uvn->u_flags & UVM_VNODE_WANTED) 270 wakeup(uvn); 271 uvn->u_flags = 0; 272 simple_unlock(&uvn->u_obj.vmobjlock); /* drop lock */ 273 UVMHIST_LOG(maphist,"<- done (VOP_GETATTR FAILED!)", 0,0,0,0); 274 return(NULL); 275 } 276 277 /* 278 * make sure that the newsize fits within a vaddr_t 279 * XXX: need to revise addressing data types 280 */ 281 #ifdef DEBUG 282 if (vp->v_type == VBLK) 283 printf("used_vnode_size = %llu\n", (long long)used_vnode_size); 284 #endif 285 286 /* 287 * now set up the uvn. 288 */ 289 uvn->u_obj.pgops = &uvm_vnodeops; 290 TAILQ_INIT(&uvn->u_obj.memq); 291 uvn->u_obj.uo_npages = 0; 292 uvn->u_obj.uo_refs = 1; /* just us... */ 293 oldflags = uvn->u_flags; 294 uvn->u_flags = UVM_VNODE_VALID|UVM_VNODE_CANPERSIST; 295 uvn->u_nio = 0; 296 uvn->u_size = used_vnode_size; 297 298 /* if write access, we need to add it to the wlist */ 299 if (accessprot & VM_PROT_WRITE) { 300 simple_lock(&uvn_wl_lock); 301 LIST_INSERT_HEAD(&uvn_wlist, uvn, u_wlist); 302 simple_unlock(&uvn_wl_lock); 303 uvn->u_flags |= UVM_VNODE_WRITEABLE; /* we are on wlist! */ 304 } 305 306 /* 307 * add a reference to the vnode. this reference will stay as long 308 * as there is a valid mapping of the vnode. dropped when the 309 * reference count goes to zero [and we either free or persist]. 310 */ 311 VREF(vp); 312 simple_unlock(&uvn->u_obj.vmobjlock); 313 if (oldflags & UVM_VNODE_WANTED) 314 wakeup(uvn); 315 316 UVMHIST_LOG(maphist,"<- done/VREF, ret %p", &uvn->u_obj,0,0,0); 317 return(&uvn->u_obj); 318 } 319 320 321 /* 322 * uvn_reference 323 * 324 * duplicate a reference to a VM object. Note that the reference 325 * count must already be at least one (the passed in reference) so 326 * there is no chance of the uvn being killed or locked out here. 327 * 328 * => caller must call with object unlocked. 329 * => caller must be using the same accessprot as was used at attach time 330 */ 331 332 333 static void 334 uvn_reference(uobj) 335 struct uvm_object *uobj; 336 { 337 #ifdef DEBUG 338 struct uvm_vnode *uvn = (struct uvm_vnode *) uobj; 339 #endif 340 UVMHIST_FUNC("uvn_reference"); UVMHIST_CALLED(maphist); 341 342 simple_lock(&uobj->vmobjlock); 343 #ifdef DEBUG 344 if ((uvn->u_flags & UVM_VNODE_VALID) == 0) { 345 printf("uvn_reference: ref=%d, flags=0x%x\n", uvn->u_flags, 346 uobj->uo_refs); 347 panic("uvn_reference: invalid state"); 348 } 349 #endif 350 uobj->uo_refs++; 351 UVMHIST_LOG(maphist, "<- done (uobj=%p, ref = %ld)", 352 uobj, uobj->uo_refs,0,0); 353 simple_unlock(&uobj->vmobjlock); 354 } 355 356 /* 357 * uvn_detach 358 * 359 * remove a reference to a VM object. 360 * 361 * => caller must call with object unlocked and map locked. 362 * => this starts the detach process, but doesn't have to finish it 363 * (async i/o could still be pending). 364 */ 365 static void 366 uvn_detach(uobj) 367 struct uvm_object *uobj; 368 { 369 struct uvm_vnode *uvn; 370 struct vnode *vp; 371 int oldflags; 372 UVMHIST_FUNC("uvn_detach"); UVMHIST_CALLED(maphist); 373 374 simple_lock(&uobj->vmobjlock); 375 376 UVMHIST_LOG(maphist," (uobj=%p) ref=%ld", uobj,uobj->uo_refs,0,0); 377 uobj->uo_refs--; /* drop ref! */ 378 if (uobj->uo_refs) { /* still more refs */ 379 simple_unlock(&uobj->vmobjlock); 380 UVMHIST_LOG(maphist, "<- done (rc>0)", 0,0,0,0); 381 return; 382 } 383 384 /* 385 * get other pointers ... 386 */ 387 388 uvn = (struct uvm_vnode *) uobj; 389 vp = (struct vnode *) uobj; 390 391 /* 392 * clear VTEXT flag now that there are no mappings left (VTEXT is used 393 * to keep an active text file from being overwritten). 394 */ 395 vp->v_flag &= ~VTEXT; 396 397 /* 398 * we just dropped the last reference to the uvn. see if we can 399 * let it "stick around". 400 */ 401 402 if (uvn->u_flags & UVM_VNODE_CANPERSIST) { 403 /* won't block */ 404 uvn_flush(uobj, 0, 0, PGO_DEACTIVATE|PGO_ALLPAGES); 405 simple_unlock(&uobj->vmobjlock); 406 vrele(vp); /* drop vnode reference */ 407 UVMHIST_LOG(maphist,"<- done/vrele! (persist)", 0,0,0,0); 408 return; 409 } 410 411 /* 412 * its a goner! 413 */ 414 415 UVMHIST_LOG(maphist," its a goner (flushing)!", 0,0,0,0); 416 417 uvn->u_flags |= UVM_VNODE_DYING; 418 419 /* 420 * even though we may unlock in flush, no one can gain a reference 421 * to us until we clear the "dying" flag [because it blocks 422 * attaches]. we will not do that until after we've disposed of all 423 * the pages with uvn_flush(). note that before the flush the only 424 * pages that could be marked PG_BUSY are ones that are in async 425 * pageout by the daemon. (there can't be any pending "get"'s 426 * because there are no references to the object). 427 */ 428 429 (void) uvn_flush(uobj, 0, 0, PGO_CLEANIT|PGO_FREE|PGO_ALLPAGES); 430 431 UVMHIST_LOG(maphist," its a goner (done flush)!", 0,0,0,0); 432 433 /* 434 * given the structure of this pager, the above flush request will 435 * create the following state: all the pages that were in the object 436 * have either been free'd or they are marked PG_BUSY|PG_RELEASED. 437 * the PG_BUSY bit was set either by us or the daemon for async I/O. 438 * in either case, if we have pages left we can't kill the object 439 * yet because i/o is pending. in this case we set the "relkill" 440 * flag which will cause pgo_releasepg to kill the object once all 441 * the I/O's are done [pgo_releasepg will be called from the aiodone 442 * routine or from the page daemon]. 443 */ 444 445 if (uobj->uo_npages) { /* I/O pending. iodone will free */ 446 #ifdef DEBUG 447 /* 448 * XXXCDC: very unlikely to happen until we have async i/o 449 * so print a little info message in case it does. 450 */ 451 printf("uvn_detach: vn %p has pages left after flush - " 452 "relkill mode\n", uobj); 453 #endif 454 uvn->u_flags |= UVM_VNODE_RELKILL; 455 simple_unlock(&uobj->vmobjlock); 456 UVMHIST_LOG(maphist,"<- done! (releasepg will kill obj)", 0, 0, 457 0, 0); 458 return; 459 } 460 461 /* 462 * kill object now. note that we can't be on the sync q because 463 * all references are gone. 464 */ 465 if (uvn->u_flags & UVM_VNODE_WRITEABLE) { 466 simple_lock(&uvn_wl_lock); /* protect uvn_wlist */ 467 LIST_REMOVE(uvn, u_wlist); 468 simple_unlock(&uvn_wl_lock); 469 } 470 #ifdef DIAGNOSTIC 471 if (!TAILQ_EMPTY(&uobj->memq)) 472 panic("uvn_deref: vnode VM object still has pages afer " 473 "syncio/free flush"); 474 #endif 475 oldflags = uvn->u_flags; 476 uvn->u_flags = 0; 477 simple_unlock(&uobj->vmobjlock); 478 479 /* wake up any sleepers */ 480 if (oldflags & UVM_VNODE_WANTED) 481 wakeup(uvn); 482 483 /* 484 * drop our reference to the vnode. 485 */ 486 vrele(vp); 487 UVMHIST_LOG(maphist,"<- done (vrele) final", 0,0,0,0); 488 489 return; 490 } 491 492 /* 493 * uvm_vnp_terminate: external hook to clear out a vnode's VM 494 * 495 * called in two cases: 496 * [1] when a persisting vnode vm object (i.e. one with a zero reference 497 * count) needs to be freed so that a vnode can be reused. this 498 * happens under "getnewvnode" in vfs_subr.c. if the vnode from 499 * the free list is still attached (i.e. not VBAD) then vgone is 500 * called. as part of the vgone trace this should get called to 501 * free the vm object. this is the common case. 502 * [2] when a filesystem is being unmounted by force (MNT_FORCE, 503 * "umount -f") the vgone() function is called on active vnodes 504 * on the mounted file systems to kill their data (the vnodes become 505 * "dead" ones [see src/sys/miscfs/deadfs/...]). that results in a 506 * call here (even if the uvn is still in use -- i.e. has a non-zero 507 * reference count). this case happens at "umount -f" and during a 508 * "reboot/halt" operation. 509 * 510 * => the caller must XLOCK and VOP_LOCK the vnode before calling us 511 * [protects us from getting a vnode that is already in the DYING 512 * state...] 513 * => unlike uvn_detach, this function must not return until all the 514 * uvn's pages are disposed of. 515 * => in case [2] the uvn is still alive after this call, but all I/O 516 * ops will fail (due to the backing vnode now being "dead"). this 517 * will prob. kill any process using the uvn due to pgo_get failing. 518 */ 519 520 void 521 uvm_vnp_terminate(vp) 522 struct vnode *vp; 523 { 524 struct uvm_vnode *uvn = &vp->v_uvm; 525 int oldflags; 526 UVMHIST_FUNC("uvm_vnp_terminate"); UVMHIST_CALLED(maphist); 527 528 /* 529 * lock object and check if it is valid 530 */ 531 simple_lock(&uvn->u_obj.vmobjlock); 532 UVMHIST_LOG(maphist, " vp=%p, ref=%ld, flag=0x%lx", vp, 533 uvn->u_obj.uo_refs, uvn->u_flags, 0); 534 if ((uvn->u_flags & UVM_VNODE_VALID) == 0) { 535 simple_unlock(&uvn->u_obj.vmobjlock); 536 UVMHIST_LOG(maphist, "<- done (not active)", 0, 0, 0, 0); 537 return; 538 } 539 540 /* 541 * must be a valid uvn that is not already dying (because XLOCK 542 * protects us from that). the uvn can't in the ALOCK state 543 * because it is valid, and uvn's that are in the ALOCK state haven't 544 * been marked valid yet. 545 */ 546 547 #ifdef DEBUG 548 /* 549 * debug check: are we yanking the vnode out from under our uvn? 550 */ 551 if (uvn->u_obj.uo_refs) { 552 printf("uvm_vnp_terminate(%p): terminating active vnode " 553 "(refs=%d)\n", uvn, uvn->u_obj.uo_refs); 554 } 555 #endif 556 557 /* 558 * it is possible that the uvn was detached and is in the relkill 559 * state [i.e. waiting for async i/o to finish so that releasepg can 560 * kill object]. we take over the vnode now and cancel the relkill. 561 * we want to know when the i/o is done so we can recycle right 562 * away. note that a uvn can only be in the RELKILL state if it 563 * has a zero reference count. 564 */ 565 566 if (uvn->u_flags & UVM_VNODE_RELKILL) 567 uvn->u_flags &= ~UVM_VNODE_RELKILL; /* cancel RELKILL */ 568 569 /* 570 * block the uvn by setting the dying flag, and then flush the 571 * pages. (note that flush may unlock object while doing I/O, but 572 * it will re-lock it before it returns control here). 573 * 574 * also, note that we tell I/O that we are already VOP_LOCK'd so 575 * that uvn_io doesn't attempt to VOP_LOCK again. 576 * 577 * XXXCDC: setting VNISLOCKED on an active uvn which is being terminated 578 * due to a forceful unmount might not be a good idea. maybe we 579 * need a way to pass in this info to uvn_flush through a 580 * pager-defined PGO_ constant [currently there are none]. 581 */ 582 uvn->u_flags |= UVM_VNODE_DYING|UVM_VNODE_VNISLOCKED; 583 584 (void) uvn_flush(&uvn->u_obj, 0, 0, PGO_CLEANIT|PGO_FREE|PGO_ALLPAGES); 585 586 /* 587 * as we just did a flush we expect all the pages to be gone or in 588 * the process of going. sleep to wait for the rest to go [via iosync]. 589 */ 590 591 while (uvn->u_obj.uo_npages) { 592 #ifdef DEBUG 593 struct vm_page *pp; 594 TAILQ_FOREACH(pp, &uvn->u_obj.memq, listq) { 595 if ((pp->flags & PG_BUSY) == 0) 596 panic("uvm_vnp_terminate: detected unbusy pg"); 597 } 598 if (uvn->u_nio == 0) 599 panic("uvm_vnp_terminate: no I/O to wait for?"); 600 printf("uvm_vnp_terminate: waiting for I/O to fin.\n"); 601 /* 602 * XXXCDC: this is unlikely to happen without async i/o so we 603 * put a printf in just to keep an eye on it. 604 */ 605 #endif 606 uvn->u_flags |= UVM_VNODE_IOSYNC; 607 UVM_UNLOCK_AND_WAIT(&uvn->u_nio, &uvn->u_obj.vmobjlock, FALSE, 608 "uvn_term",0); 609 simple_lock(&uvn->u_obj.vmobjlock); 610 } 611 612 /* 613 * done. now we free the uvn if its reference count is zero 614 * (true if we are zapping a persisting uvn). however, if we are 615 * terminating a uvn with active mappings we let it live ... future 616 * calls down to the vnode layer will fail. 617 */ 618 619 oldflags = uvn->u_flags; 620 if (uvn->u_obj.uo_refs) { 621 622 /* 623 * uvn must live on it is dead-vnode state until all references 624 * are gone. restore flags. clear CANPERSIST state. 625 */ 626 627 uvn->u_flags &= ~(UVM_VNODE_DYING|UVM_VNODE_VNISLOCKED| 628 UVM_VNODE_WANTED|UVM_VNODE_CANPERSIST); 629 630 } else { 631 632 /* 633 * free the uvn now. note that the VREF reference is already 634 * gone [it is dropped when we enter the persist state]. 635 */ 636 if (uvn->u_flags & UVM_VNODE_IOSYNCWANTED) 637 panic("uvm_vnp_terminate: io sync wanted bit set"); 638 639 if (uvn->u_flags & UVM_VNODE_WRITEABLE) { 640 simple_lock(&uvn_wl_lock); 641 LIST_REMOVE(uvn, u_wlist); 642 simple_unlock(&uvn_wl_lock); 643 } 644 uvn->u_flags = 0; /* uvn is history, clear all bits */ 645 } 646 647 if (oldflags & UVM_VNODE_WANTED) 648 wakeup(uvn); /* object lock still held */ 649 650 simple_unlock(&uvn->u_obj.vmobjlock); 651 UVMHIST_LOG(maphist, "<- done", 0, 0, 0, 0); 652 653 } 654 655 /* 656 * uvn_releasepg: handled a released page in a uvn 657 * 658 * => "pg" is a PG_BUSY [caller owns it], PG_RELEASED page that we need 659 * to dispose of. 660 * => caller must handled PG_WANTED case 661 * => called with page's object locked, pageq's unlocked 662 * => returns TRUE if page's object is still alive, FALSE if we 663 * killed the page's object. if we return TRUE, then we 664 * return with the object locked. 665 * => if (nextpgp != NULL) => we return pageq.tqe_next here, and return 666 * with the page queues locked [for pagedaemon] 667 * => if (nextpgp == NULL) => we return with page queues unlocked [normal case] 668 * => we kill the uvn if it is not referenced and we are suppose to 669 * kill it ("relkill"). 670 */ 671 672 boolean_t 673 uvn_releasepg(pg, nextpgp) 674 struct vm_page *pg; 675 struct vm_page **nextpgp; /* OUT */ 676 { 677 struct uvm_vnode *uvn = (struct uvm_vnode *) pg->uobject; 678 #ifdef DIAGNOSTIC 679 if ((pg->flags & PG_RELEASED) == 0) 680 panic("uvn_releasepg: page not released!"); 681 #endif 682 683 /* 684 * dispose of the page [caller handles PG_WANTED] 685 */ 686 pmap_page_protect(pg, VM_PROT_NONE); 687 uvm_lock_pageq(); 688 if (nextpgp) 689 *nextpgp = TAILQ_NEXT(pg, pageq); /* next page for daemon */ 690 uvm_pagefree(pg); 691 if (!nextpgp) 692 uvm_unlock_pageq(); 693 694 /* 695 * now see if we need to kill the object 696 */ 697 if (uvn->u_flags & UVM_VNODE_RELKILL) { 698 if (uvn->u_obj.uo_refs) 699 panic("uvn_releasepg: kill flag set on referenced " 700 "object!"); 701 if (uvn->u_obj.uo_npages == 0) { 702 if (uvn->u_flags & UVM_VNODE_WRITEABLE) { 703 simple_lock(&uvn_wl_lock); 704 LIST_REMOVE(uvn, u_wlist); 705 simple_unlock(&uvn_wl_lock); 706 } 707 #ifdef DIAGNOSTIC 708 if (!TAILQ_EMPTY(&uvn->u_obj.memq)) 709 panic("uvn_releasepg: pages in object with npages == 0"); 710 #endif 711 if (uvn->u_flags & UVM_VNODE_WANTED) 712 /* still holding object lock */ 713 wakeup(uvn); 714 715 uvn->u_flags = 0; /* DEAD! */ 716 simple_unlock(&uvn->u_obj.vmobjlock); 717 return (FALSE); 718 } 719 } 720 return (TRUE); 721 } 722 723 /* 724 * NOTE: currently we have to use VOP_READ/VOP_WRITE because they go 725 * through the buffer cache and allow I/O in any size. These VOPs use 726 * synchronous i/o. [vs. VOP_STRATEGY which can be async, but doesn't 727 * go through the buffer cache or allow I/O sizes larger than a 728 * block]. we will eventually want to change this. 729 * 730 * issues to consider: 731 * uvm provides the uvm_aiodesc structure for async i/o management. 732 * there are two tailq's in the uvm. structure... one for pending async 733 * i/o and one for "done" async i/o. to do an async i/o one puts 734 * an aiodesc on the "pending" list (protected by splbio()), starts the 735 * i/o and returns VM_PAGER_PEND. when the i/o is done, we expect 736 * some sort of "i/o done" function to be called (at splbio(), interrupt 737 * time). this function should remove the aiodesc from the pending list 738 * and place it on the "done" list and wakeup the daemon. the daemon 739 * will run at normal spl() and will remove all items from the "done" 740 * list and call the "aiodone" hook for each done request (see uvm_pager.c). 741 * [in the old vm code, this was done by calling the "put" routine with 742 * null arguments which made the code harder to read and understand because 743 * you had one function ("put") doing two things.] 744 * 745 * so the current pager needs: 746 * int uvn_aiodone(struct uvm_aiodesc *) 747 * 748 * => return KERN_SUCCESS (aio finished, free it). otherwise requeue for 749 * later collection. 750 * => called with pageq's locked by the daemon. 751 * 752 * general outline: 753 * - "try" to lock object. if fail, just return (will try again later) 754 * - drop "u_nio" (this req is done!) 755 * - if (object->iosync && u_naio == 0) { wakeup &uvn->u_naio } 756 * - get "page" structures (atop?). 757 * - handle "wanted" pages 758 * - handle "released" pages [using pgo_releasepg] 759 * >>> pgo_releasepg may kill the object 760 * dont forget to look at "object" wanted flag in all cases. 761 */ 762 763 764 /* 765 * uvn_flush: flush pages out of a uvm object. 766 * 767 * => object should be locked by caller. we may _unlock_ the object 768 * if (and only if) we need to clean a page (PGO_CLEANIT). 769 * we return with the object locked. 770 * => if PGO_CLEANIT is set, we may block (due to I/O). thus, a caller 771 * might want to unlock higher level resources (e.g. vm_map) 772 * before calling flush. 773 * => if PGO_CLEANIT is not set, then we will neither unlock the object 774 * or block. 775 * => if PGO_ALLPAGE is set, then all pages in the object are valid targets 776 * for flushing. 777 * => NOTE: we rely on the fact that the object's memq is a TAILQ and 778 * that new pages are inserted on the tail end of the list. thus, 779 * we can make a complete pass through the object in one go by starting 780 * at the head and working towards the tail (new pages are put in 781 * front of us). 782 * => NOTE: we are allowed to lock the page queues, so the caller 783 * must not be holding the lock on them [e.g. pagedaemon had 784 * better not call us with the queues locked] 785 * => we return TRUE unless we encountered some sort of I/O error 786 * 787 * comment on "cleaning" object and PG_BUSY pages: 788 * this routine is holding the lock on the object. the only time 789 * that it can run into a PG_BUSY page that it does not own is if 790 * some other process has started I/O on the page (e.g. either 791 * a pagein, or a pageout). if the PG_BUSY page is being paged 792 * in, then it can not be dirty (!PG_CLEAN) because no one has 793 * had a chance to modify it yet. if the PG_BUSY page is being 794 * paged out then it means that someone else has already started 795 * cleaning the page for us (how nice!). in this case, if we 796 * have syncio specified, then after we make our pass through the 797 * object we need to wait for the other PG_BUSY pages to clear 798 * off (i.e. we need to do an iosync). also note that once a 799 * page is PG_BUSY it must stay in its object until it is un-busyed. 800 * 801 * note on page traversal: 802 * we can traverse the pages in an object either by going down the 803 * linked list in "uobj->memq", or we can go over the address range 804 * by page doing hash table lookups for each address. depending 805 * on how many pages are in the object it may be cheaper to do one 806 * or the other. we set "by_list" to true if we are using memq. 807 * if the cost of a hash lookup was equal to the cost of the list 808 * traversal we could compare the number of pages in the start->stop 809 * range to the total number of pages in the object. however, it 810 * seems that a hash table lookup is more expensive than the linked 811 * list traversal, so we multiply the number of pages in the 812 * start->stop range by a penalty which we define below. 813 */ 814 815 #define UVN_HASH_PENALTY 4 /* XXX: a guess */ 816 817 static boolean_t 818 uvn_flush(uobj, start, stop, flags) 819 struct uvm_object *uobj; 820 voff_t start, stop; 821 int flags; 822 { 823 struct uvm_vnode *uvn = (struct uvm_vnode *) uobj; 824 struct vm_page *pp, *ppnext, *ptmp; 825 struct vm_page *pps[MAXBSIZE >> PAGE_SHIFT], **ppsp; 826 int npages, result, lcv; 827 boolean_t retval, need_iosync, by_list, needs_clean, all; 828 voff_t curoff; 829 u_short pp_version; 830 UVMHIST_FUNC("uvn_flush"); UVMHIST_CALLED(maphist); 831 832 curoff = 0; /* XXX: shut up gcc */ 833 /* 834 * get init vals and determine how we are going to traverse object 835 */ 836 837 need_iosync = FALSE; 838 retval = TRUE; /* return value */ 839 if (flags & PGO_ALLPAGES) { 840 all = TRUE; 841 by_list = TRUE; /* always go by the list */ 842 } else { 843 start = trunc_page(start); 844 stop = round_page(stop); 845 #ifdef DEBUG 846 if (stop > round_page(uvn->u_size)) 847 printf("uvn_flush: strange, got an out of range " 848 "flush (fixed)\n"); 849 #endif 850 all = FALSE; 851 by_list = (uobj->uo_npages <= 852 ((stop - start) >> PAGE_SHIFT) * UVN_HASH_PENALTY); 853 } 854 855 UVMHIST_LOG(maphist, 856 " flush start=0x%lx, stop=0x%lx, by_list=%ld, flags=0x%lx", 857 (u_long)start, (u_long)stop, by_list, flags); 858 859 /* 860 * PG_CLEANCHK: this bit is used by the pgo_mk_pcluster function as 861 * a _hint_ as to how up to date the PG_CLEAN bit is. if the hint 862 * is wrong it will only prevent us from clustering... it won't break 863 * anything. we clear all PG_CLEANCHK bits here, and pgo_mk_pcluster 864 * will set them as it syncs PG_CLEAN. This is only an issue if we 865 * are looking at non-inactive pages (because inactive page's PG_CLEAN 866 * bit is always up to date since there are no mappings). 867 * [borrowed PG_CLEANCHK idea from FreeBSD VM] 868 */ 869 870 if ((flags & PGO_CLEANIT) != 0 && 871 uobj->pgops->pgo_mk_pcluster != NULL) { 872 if (by_list) { 873 TAILQ_FOREACH(pp, &uobj->memq, listq) { 874 if (!all && 875 (pp->offset < start || pp->offset >= stop)) 876 continue; 877 pp->flags &= ~PG_CLEANCHK; 878 } 879 880 } else { /* by hash */ 881 for (curoff = start ; curoff < stop; 882 curoff += PAGE_SIZE) { 883 pp = uvm_pagelookup(uobj, curoff); 884 if (pp) 885 pp->flags &= ~PG_CLEANCHK; 886 } 887 } 888 } 889 890 /* 891 * now do it. note: we must update ppnext in body of loop or we 892 * will get stuck. we need to use ppnext because we may free "pp" 893 * before doing the next loop. 894 */ 895 896 if (by_list) { 897 pp = TAILQ_FIRST(&uobj->memq); 898 } else { 899 curoff = start; 900 pp = uvm_pagelookup(uobj, curoff); 901 } 902 903 ppnext = NULL; /* XXX: shut up gcc */ 904 ppsp = NULL; /* XXX: shut up gcc */ 905 uvm_lock_pageq(); /* page queues locked */ 906 907 /* locked: both page queues and uobj */ 908 for ( ; (by_list && pp != NULL) || 909 (!by_list && curoff < stop) ; pp = ppnext) { 910 911 if (by_list) { 912 913 /* 914 * range check 915 */ 916 917 if (!all && 918 (pp->offset < start || pp->offset >= stop)) { 919 ppnext = TAILQ_NEXT(pp, listq); 920 continue; 921 } 922 923 } else { 924 925 /* 926 * null check 927 */ 928 929 curoff += PAGE_SIZE; 930 if (pp == NULL) { 931 if (curoff < stop) 932 ppnext = uvm_pagelookup(uobj, curoff); 933 continue; 934 } 935 936 } 937 938 /* 939 * handle case where we do not need to clean page (either 940 * because we are not clean or because page is not dirty or 941 * is busy): 942 * 943 * NOTE: we are allowed to deactivate a non-wired active 944 * PG_BUSY page, but once a PG_BUSY page is on the inactive 945 * queue it must stay put until it is !PG_BUSY (so as not to 946 * confuse pagedaemon). 947 */ 948 949 if ((flags & PGO_CLEANIT) == 0 || (pp->flags & PG_BUSY) != 0) { 950 needs_clean = FALSE; 951 if ((pp->flags & PG_BUSY) != 0 && 952 (flags & (PGO_CLEANIT|PGO_SYNCIO)) == 953 (PGO_CLEANIT|PGO_SYNCIO)) 954 need_iosync = TRUE; 955 } else { 956 /* 957 * freeing: nuke all mappings so we can sync 958 * PG_CLEAN bit with no race 959 */ 960 if ((pp->flags & PG_CLEAN) != 0 && 961 (flags & PGO_FREE) != 0 && 962 (pp->pqflags & PQ_ACTIVE) != 0) 963 pmap_page_protect(pp, VM_PROT_NONE); 964 if ((pp->flags & PG_CLEAN) != 0 && 965 pmap_is_modified(pp)) 966 pp->flags &= ~(PG_CLEAN); 967 pp->flags |= PG_CLEANCHK; /* update "hint" */ 968 969 needs_clean = ((pp->flags & PG_CLEAN) == 0); 970 } 971 972 /* 973 * if we don't need a clean... load ppnext and dispose of pp 974 */ 975 if (!needs_clean) { 976 /* load ppnext */ 977 if (by_list) 978 ppnext = TAILQ_NEXT(pp, listq); 979 else { 980 if (curoff < stop) 981 ppnext = uvm_pagelookup(uobj, curoff); 982 } 983 984 /* now dispose of pp */ 985 if (flags & PGO_DEACTIVATE) { 986 if ((pp->pqflags & PQ_INACTIVE) == 0 && 987 pp->wire_count == 0) { 988 pmap_page_protect(pp, VM_PROT_NONE); 989 uvm_pagedeactivate(pp); 990 } 991 992 } else if (flags & PGO_FREE) { 993 if (pp->flags & PG_BUSY) { 994 /* release busy pages */ 995 pp->flags |= PG_RELEASED; 996 } else { 997 pmap_page_protect(pp, VM_PROT_NONE); 998 /* removed page from object */ 999 uvm_pagefree(pp); 1000 } 1001 } 1002 /* ppnext is valid so we can continue... */ 1003 continue; 1004 } 1005 1006 /* 1007 * pp points to a page in the locked object that we are 1008 * working on. if it is !PG_CLEAN,!PG_BUSY and we asked 1009 * for cleaning (PGO_CLEANIT). we clean it now. 1010 * 1011 * let uvm_pager_put attempted a clustered page out. 1012 * note: locked: uobj and page queues. 1013 */ 1014 1015 pp->flags |= PG_BUSY; /* we 'own' page now */ 1016 UVM_PAGE_OWN(pp, "uvn_flush"); 1017 pmap_page_protect(pp, VM_PROT_READ); 1018 pp_version = pp->version; 1019 ReTry: 1020 ppsp = pps; 1021 npages = sizeof(pps) / sizeof(struct vm_page *); 1022 1023 /* locked: page queues, uobj */ 1024 result = uvm_pager_put(uobj, pp, &ppsp, &npages, 1025 flags | PGO_DOACTCLUST, start, stop); 1026 /* unlocked: page queues, uobj */ 1027 1028 /* 1029 * at this point nothing is locked. if we did an async I/O 1030 * it is remotely possible for the async i/o to complete and 1031 * the page "pp" be freed or what not before we get a chance 1032 * to relock the object. in order to detect this, we have 1033 * saved the version number of the page in "pp_version". 1034 */ 1035 1036 /* relock! */ 1037 simple_lock(&uobj->vmobjlock); 1038 uvm_lock_pageq(); 1039 1040 /* 1041 * VM_PAGER_AGAIN: given the structure of this pager, this 1042 * can only happen when we are doing async I/O and can't 1043 * map the pages into kernel memory (pager_map) due to lack 1044 * of vm space. if this happens we drop back to sync I/O. 1045 */ 1046 1047 if (result == VM_PAGER_AGAIN) { 1048 /* 1049 * it is unlikely, but page could have been released 1050 * while we had the object lock dropped. we ignore 1051 * this now and retry the I/O. we will detect and 1052 * handle the released page after the syncio I/O 1053 * completes. 1054 */ 1055 #ifdef DIAGNOSTIC 1056 if (flags & PGO_SYNCIO) 1057 panic("uvn_flush: PGO_SYNCIO return 'try again' error (impossible)"); 1058 #endif 1059 flags |= PGO_SYNCIO; 1060 goto ReTry; 1061 } 1062 1063 /* 1064 * the cleaning operation is now done. finish up. note that 1065 * on error (!OK, !PEND) uvm_pager_put drops the cluster for us. 1066 * if success (OK, PEND) then uvm_pager_put returns the cluster 1067 * to us in ppsp/npages. 1068 */ 1069 1070 /* 1071 * for pending async i/o if we are not deactivating/freeing 1072 * we can move on to the next page. 1073 */ 1074 1075 if (result == VM_PAGER_PEND) { 1076 1077 if ((flags & (PGO_DEACTIVATE|PGO_FREE)) == 0) { 1078 /* 1079 * no per-page ops: refresh ppnext and continue 1080 */ 1081 if (by_list) { 1082 if (pp->version == pp_version) 1083 ppnext = TAILQ_NEXT(pp, listq); 1084 else 1085 /* reset */ 1086 ppnext = TAILQ_FIRST(&uobj->memq); 1087 } else { 1088 if (curoff < stop) 1089 ppnext = uvm_pagelookup(uobj, 1090 curoff); 1091 } 1092 continue; 1093 } 1094 1095 /* need to do anything here? */ 1096 } 1097 1098 /* 1099 * need to look at each page of the I/O operation. we defer 1100 * processing "pp" until the last trip through this "for" loop 1101 * so that we can load "ppnext" for the main loop after we 1102 * play with the cluster pages [thus the "npages + 1" in the 1103 * loop below]. 1104 */ 1105 1106 for (lcv = 0 ; lcv < npages + 1 ; lcv++) { 1107 1108 /* 1109 * handle ppnext for outside loop, and saving pp 1110 * until the end. 1111 */ 1112 if (lcv < npages) { 1113 if (ppsp[lcv] == pp) 1114 continue; /* skip pp until the end */ 1115 ptmp = ppsp[lcv]; 1116 } else { 1117 ptmp = pp; 1118 1119 /* set up next page for outer loop */ 1120 if (by_list) { 1121 if (pp->version == pp_version) 1122 ppnext = TAILQ_NEXT(pp, listq); 1123 else 1124 /* reset */ 1125 ppnext = TAILQ_FIRST(&uobj->memq); 1126 } else { 1127 if (curoff < stop) 1128 ppnext = uvm_pagelookup(uobj, curoff); 1129 } 1130 } 1131 1132 /* 1133 * verify the page didn't get moved while obj was 1134 * unlocked 1135 */ 1136 if (result == VM_PAGER_PEND && ptmp->uobject != uobj) 1137 continue; 1138 1139 /* 1140 * unbusy the page if I/O is done. note that for 1141 * pending I/O it is possible that the I/O op 1142 * finished before we relocked the object (in 1143 * which case the page is no longer busy). 1144 */ 1145 1146 if (result != VM_PAGER_PEND) { 1147 if (ptmp->flags & PG_WANTED) 1148 /* still holding object lock */ 1149 wakeup(ptmp); 1150 1151 ptmp->flags &= ~(PG_WANTED|PG_BUSY); 1152 UVM_PAGE_OWN(ptmp, NULL); 1153 if (ptmp->flags & PG_RELEASED) { 1154 1155 /* pgo_releasepg wants this */ 1156 uvm_unlock_pageq(); 1157 if (!uvn_releasepg(ptmp, NULL)) 1158 return (TRUE); 1159 1160 uvm_lock_pageq(); /* relock */ 1161 continue; /* next page */ 1162 1163 } else { 1164 ptmp->flags |= (PG_CLEAN|PG_CLEANCHK); 1165 if ((flags & PGO_FREE) == 0) 1166 pmap_clear_modify(ptmp); 1167 } 1168 } 1169 1170 /* 1171 * dispose of page 1172 */ 1173 1174 if (flags & PGO_DEACTIVATE) { 1175 if ((pp->pqflags & PQ_INACTIVE) == 0 && 1176 pp->wire_count == 0) { 1177 pmap_page_protect(ptmp, VM_PROT_NONE); 1178 uvm_pagedeactivate(ptmp); 1179 } 1180 1181 } else if (flags & PGO_FREE) { 1182 if (result == VM_PAGER_PEND) { 1183 if ((ptmp->flags & PG_BUSY) != 0) 1184 /* signal for i/o done */ 1185 ptmp->flags |= PG_RELEASED; 1186 } else { 1187 if (result != VM_PAGER_OK) { 1188 printf("uvn_flush: obj=%p, " 1189 "offset=0x%llx. error " 1190 "during pageout.\n", 1191 pp->uobject, 1192 (long long)pp->offset); 1193 printf("uvn_flush: WARNING: " 1194 "changes to page may be " 1195 "lost!\n"); 1196 retval = FALSE; 1197 } 1198 pmap_page_protect(ptmp, VM_PROT_NONE); 1199 uvm_pagefree(ptmp); 1200 } 1201 } 1202 1203 } /* end of "lcv" for loop */ 1204 1205 } /* end of "pp" for loop */ 1206 1207 /* 1208 * done with pagequeues: unlock 1209 */ 1210 uvm_unlock_pageq(); 1211 1212 /* 1213 * now wait for all I/O if required. 1214 */ 1215 if (need_iosync) { 1216 1217 UVMHIST_LOG(maphist," <<DOING IOSYNC>>",0,0,0,0); 1218 while (uvn->u_nio != 0) { 1219 uvn->u_flags |= UVM_VNODE_IOSYNC; 1220 UVM_UNLOCK_AND_WAIT(&uvn->u_nio, &uvn->u_obj.vmobjlock, 1221 FALSE, "uvn_flush",0); 1222 simple_lock(&uvn->u_obj.vmobjlock); 1223 } 1224 if (uvn->u_flags & UVM_VNODE_IOSYNCWANTED) 1225 wakeup(&uvn->u_flags); 1226 uvn->u_flags &= ~(UVM_VNODE_IOSYNC|UVM_VNODE_IOSYNCWANTED); 1227 } 1228 1229 /* return, with object locked! */ 1230 UVMHIST_LOG(maphist,"<- done (retval=0x%lx)",retval,0,0,0); 1231 return(retval); 1232 } 1233 1234 /* 1235 * uvn_cluster 1236 * 1237 * we are about to do I/O in an object at offset. this function is called 1238 * to establish a range of offsets around "offset" in which we can cluster 1239 * I/O. 1240 * 1241 * - currently doesn't matter if obj locked or not. 1242 */ 1243 1244 static void 1245 uvn_cluster(uobj, offset, loffset, hoffset) 1246 struct uvm_object *uobj; 1247 voff_t offset; 1248 voff_t *loffset, *hoffset; /* OUT */ 1249 { 1250 struct uvm_vnode *uvn = (struct uvm_vnode *) uobj; 1251 *loffset = offset; 1252 1253 if (*loffset >= uvn->u_size) 1254 panic("uvn_cluster: offset out of range"); 1255 1256 /* 1257 * XXX: old pager claims we could use VOP_BMAP to get maxcontig value. 1258 */ 1259 *hoffset = *loffset + MAXBSIZE; 1260 if (*hoffset > round_page(uvn->u_size)) /* past end? */ 1261 *hoffset = round_page(uvn->u_size); 1262 1263 return; 1264 } 1265 1266 /* 1267 * uvn_put: flush page data to backing store. 1268 * 1269 * => prefer map unlocked (not required) 1270 * => object must be locked! we will _unlock_ it before starting I/O. 1271 * => flags: PGO_SYNCIO -- use sync. I/O 1272 * => note: caller must set PG_CLEAN and pmap_clear_modify (if needed) 1273 * => XXX: currently we use VOP_READ/VOP_WRITE which are only sync. 1274 * [thus we never do async i/o! see iodone comment] 1275 */ 1276 1277 static int 1278 uvn_put(uobj, pps, npages, flags) 1279 struct uvm_object *uobj; 1280 struct vm_page **pps; 1281 int npages, flags; 1282 { 1283 int retval; 1284 1285 /* note: object locked */ 1286 retval = uvn_io((struct uvm_vnode*)uobj, pps, npages, flags, UIO_WRITE); 1287 /* note: object unlocked */ 1288 1289 return(retval); 1290 } 1291 1292 1293 /* 1294 * uvn_get: get pages (synchronously) from backing store 1295 * 1296 * => prefer map unlocked (not required) 1297 * => object must be locked! we will _unlock_ it before starting any I/O. 1298 * => flags: PGO_ALLPAGES: get all of the pages 1299 * PGO_LOCKED: fault data structures are locked 1300 * => NOTE: offset is the offset of pps[0], _NOT_ pps[centeridx] 1301 * => NOTE: caller must check for released pages!! 1302 */ 1303 1304 static int 1305 uvn_get(uobj, offset, pps, npagesp, centeridx, access_type, advice, flags) 1306 struct uvm_object *uobj; 1307 voff_t offset; 1308 struct vm_page **pps; /* IN/OUT */ 1309 int *npagesp; /* IN (OUT if PGO_LOCKED) */ 1310 int centeridx, advice, flags; 1311 vm_prot_t access_type; 1312 { 1313 voff_t current_offset; 1314 struct vm_page *ptmp; 1315 int lcv, result, gotpages; 1316 boolean_t done; 1317 UVMHIST_FUNC("uvn_get"); UVMHIST_CALLED(maphist); 1318 UVMHIST_LOG(maphist, "flags=%ld", flags,0,0,0); 1319 1320 /* 1321 * step 1: handled the case where fault data structures are locked. 1322 */ 1323 1324 if (flags & PGO_LOCKED) { 1325 1326 /* 1327 * gotpages is the current number of pages we've gotten (which 1328 * we pass back up to caller via *npagesp. 1329 */ 1330 1331 gotpages = 0; 1332 1333 /* 1334 * step 1a: get pages that are already resident. only do this 1335 * if the data structures are locked (i.e. the first time 1336 * through). 1337 */ 1338 1339 done = TRUE; /* be optimistic */ 1340 1341 for (lcv = 0, current_offset = offset ; lcv < *npagesp ; 1342 lcv++, current_offset += PAGE_SIZE) { 1343 1344 /* do we care about this page? if not, skip it */ 1345 if (pps[lcv] == PGO_DONTCARE) 1346 continue; 1347 1348 /* lookup page */ 1349 ptmp = uvm_pagelookup(uobj, current_offset); 1350 1351 /* to be useful must get a non-busy, non-released pg */ 1352 if (ptmp == NULL || 1353 (ptmp->flags & (PG_BUSY|PG_RELEASED)) != 0) { 1354 if (lcv == centeridx || (flags & PGO_ALLPAGES) 1355 != 0) 1356 done = FALSE; /* need to do a wait or I/O! */ 1357 continue; 1358 } 1359 1360 /* 1361 * useful page: busy/lock it and plug it in our 1362 * result array 1363 */ 1364 ptmp->flags |= PG_BUSY; /* loan up to caller */ 1365 UVM_PAGE_OWN(ptmp, "uvn_get1"); 1366 pps[lcv] = ptmp; 1367 gotpages++; 1368 1369 } /* "for" lcv loop */ 1370 1371 /* 1372 * XXX: given the "advice", should we consider async read-ahead? 1373 * XXX: fault current does deactive of pages behind us. is 1374 * this good (other callers might now). 1375 */ 1376 /* 1377 * XXX: read-ahead currently handled by buffer cache (bread) 1378 * level. 1379 * XXX: no async i/o available. 1380 * XXX: so we don't do anything now. 1381 */ 1382 1383 /* 1384 * step 1c: now we've either done everything needed or we to 1385 * unlock and do some waiting or I/O. 1386 */ 1387 1388 *npagesp = gotpages; /* let caller know */ 1389 if (done) 1390 return(VM_PAGER_OK); /* bingo! */ 1391 else 1392 /* EEK! Need to unlock and I/O */ 1393 return(VM_PAGER_UNLOCK); 1394 } 1395 1396 /* 1397 * step 2: get non-resident or busy pages. 1398 * object is locked. data structures are unlocked. 1399 * 1400 * XXX: because we can't do async I/O at this level we get things 1401 * page at a time (otherwise we'd chunk). the VOP_READ() will do 1402 * async-read-ahead for us at a lower level. 1403 */ 1404 1405 for (lcv = 0, current_offset = offset; 1406 lcv < *npagesp ; lcv++, current_offset += PAGE_SIZE) { 1407 1408 /* skip over pages we've already gotten or don't want */ 1409 /* skip over pages we don't _have_ to get */ 1410 if (pps[lcv] != NULL || (lcv != centeridx && 1411 (flags & PGO_ALLPAGES) == 0)) 1412 continue; 1413 1414 /* 1415 * we have yet to locate the current page (pps[lcv]). we first 1416 * look for a page that is already at the current offset. if 1417 * we fine a page, we check to see if it is busy or released. 1418 * if that is the case, then we sleep on the page until it is 1419 * no longer busy or released and repeat the lookup. if the 1420 * page we found is neither busy nor released, then we busy it 1421 * (so we own it) and plug it into pps[lcv]. this breaks the 1422 * following while loop and indicates we are ready to move on 1423 * to the next page in the "lcv" loop above. 1424 * 1425 * if we exit the while loop with pps[lcv] still set to NULL, 1426 * then it means that we allocated a new busy/fake/clean page 1427 * ptmp in the object and we need to do I/O to fill in the data. 1428 */ 1429 1430 while (pps[lcv] == NULL) { /* top of "pps" while loop */ 1431 1432 /* look for a current page */ 1433 ptmp = uvm_pagelookup(uobj, current_offset); 1434 1435 /* nope? allocate one now (if we can) */ 1436 if (ptmp == NULL) { 1437 1438 ptmp = uvm_pagealloc(uobj, current_offset, 1439 NULL, 0); 1440 1441 /* out of RAM? */ 1442 if (ptmp == NULL) { 1443 simple_unlock(&uobj->vmobjlock); 1444 uvm_wait("uvn_getpage"); 1445 simple_lock(&uobj->vmobjlock); 1446 1447 /* goto top of pps while loop */ 1448 continue; 1449 } 1450 1451 /* 1452 * got new page ready for I/O. break pps 1453 * while loop. pps[lcv] is still NULL. 1454 */ 1455 break; 1456 } 1457 1458 /* page is there, see if we need to wait on it */ 1459 if ((ptmp->flags & (PG_BUSY|PG_RELEASED)) != 0) { 1460 ptmp->flags |= PG_WANTED; 1461 UVM_UNLOCK_AND_WAIT(ptmp, 1462 &uobj->vmobjlock, FALSE, "uvn_get",0); 1463 simple_lock(&uobj->vmobjlock); 1464 continue; /* goto top of pps while loop */ 1465 } 1466 1467 /* 1468 * if we get here then the page has become resident 1469 * and unbusy between steps 1 and 2. we busy it 1470 * now (so we own it) and set pps[lcv] (so that we 1471 * exit the while loop). 1472 */ 1473 ptmp->flags |= PG_BUSY; 1474 UVM_PAGE_OWN(ptmp, "uvn_get2"); 1475 pps[lcv] = ptmp; 1476 } 1477 1478 /* 1479 * if we own the a valid page at the correct offset, pps[lcv] 1480 * will point to it. nothing more to do except go to the 1481 * next page. 1482 */ 1483 1484 if (pps[lcv]) 1485 continue; /* next lcv */ 1486 1487 /* 1488 * we have a "fake/busy/clean" page that we just allocated. do 1489 * I/O to fill it with valid data. note that object must be 1490 * locked going into uvn_io, but will be unlocked afterwards. 1491 */ 1492 1493 result = uvn_io((struct uvm_vnode *) uobj, &ptmp, 1, 1494 PGO_SYNCIO, UIO_READ); 1495 1496 /* 1497 * I/O done. object is unlocked (by uvn_io). because we used 1498 * syncio the result can not be PEND or AGAIN. we must relock 1499 * and check for errors. 1500 */ 1501 1502 /* lock object. check for errors. */ 1503 simple_lock(&uobj->vmobjlock); 1504 if (result != VM_PAGER_OK) { 1505 if (ptmp->flags & PG_WANTED) 1506 /* object lock still held */ 1507 wakeup(ptmp); 1508 1509 ptmp->flags &= ~(PG_WANTED|PG_BUSY); 1510 UVM_PAGE_OWN(ptmp, NULL); 1511 uvm_lock_pageq(); 1512 uvm_pagefree(ptmp); 1513 uvm_unlock_pageq(); 1514 simple_unlock(&uobj->vmobjlock); 1515 return(result); 1516 } 1517 1518 /* 1519 * we got the page! clear the fake flag (indicates valid 1520 * data now in page) and plug into our result array. note 1521 * that page is still busy. 1522 * 1523 * it is the callers job to: 1524 * => check if the page is released 1525 * => unbusy the page 1526 * => activate the page 1527 */ 1528 1529 ptmp->flags &= ~PG_FAKE; /* data is valid ... */ 1530 pmap_clear_modify(ptmp); /* ... and clean */ 1531 pps[lcv] = ptmp; 1532 1533 } /* lcv loop */ 1534 1535 /* 1536 * finally, unlock object and return. 1537 */ 1538 1539 simple_unlock(&uobj->vmobjlock); 1540 return (VM_PAGER_OK); 1541 } 1542 1543 /* 1544 * uvn_io: do I/O to a vnode 1545 * 1546 * => prefer map unlocked (not required) 1547 * => object must be locked! we will _unlock_ it before starting I/O. 1548 * => flags: PGO_SYNCIO -- use sync. I/O 1549 * => XXX: currently we use VOP_READ/VOP_WRITE which are only sync. 1550 * [thus we never do async i/o! see iodone comment] 1551 */ 1552 1553 static int 1554 uvn_io(uvn, pps, npages, flags, rw) 1555 struct uvm_vnode *uvn; 1556 vm_page_t *pps; 1557 int npages, flags, rw; 1558 { 1559 struct vnode *vn; 1560 struct uio uio; 1561 struct iovec iov; 1562 vaddr_t kva; 1563 off_t file_offset; 1564 int waitf, result, mapinflags; 1565 size_t got, wanted; 1566 UVMHIST_FUNC("uvn_io"); UVMHIST_CALLED(maphist); 1567 1568 UVMHIST_LOG(maphist, "rw=%ld", rw,0,0,0); 1569 1570 /* 1571 * init values 1572 */ 1573 1574 waitf = (flags & PGO_SYNCIO) ? M_WAITOK : M_NOWAIT; 1575 vn = (struct vnode *) uvn; 1576 file_offset = pps[0]->offset; 1577 1578 /* 1579 * check for sync'ing I/O. 1580 */ 1581 1582 while (uvn->u_flags & UVM_VNODE_IOSYNC) { 1583 if (waitf == M_NOWAIT) { 1584 simple_unlock(&uvn->u_obj.vmobjlock); 1585 UVMHIST_LOG(maphist,"<- try again (iosync)",0,0,0,0); 1586 return(VM_PAGER_AGAIN); 1587 } 1588 uvn->u_flags |= UVM_VNODE_IOSYNCWANTED; 1589 UVM_UNLOCK_AND_WAIT(&uvn->u_flags, &uvn->u_obj.vmobjlock, 1590 FALSE, "uvn_iosync",0); 1591 simple_lock(&uvn->u_obj.vmobjlock); 1592 } 1593 1594 /* 1595 * check size 1596 */ 1597 1598 if (file_offset >= uvn->u_size) { 1599 simple_unlock(&uvn->u_obj.vmobjlock); 1600 UVMHIST_LOG(maphist,"<- BAD (size check)",0,0,0,0); 1601 return(VM_PAGER_BAD); 1602 } 1603 1604 /* 1605 * first try and map the pages in (without waiting) 1606 */ 1607 1608 mapinflags = (rw == UIO_READ) ? 1609 UVMPAGER_MAPIN_READ : UVMPAGER_MAPIN_WRITE; 1610 1611 kva = uvm_pagermapin(pps, npages, mapinflags); 1612 if (kva == 0 && waitf == M_NOWAIT) { 1613 simple_unlock(&uvn->u_obj.vmobjlock); 1614 UVMHIST_LOG(maphist,"<- mapin failed (try again)",0,0,0,0); 1615 return(VM_PAGER_AGAIN); 1616 } 1617 1618 /* 1619 * ok, now bump u_nio up. at this point we are done with uvn 1620 * and can unlock it. if we still don't have a kva, try again 1621 * (this time with sleep ok). 1622 */ 1623 1624 uvn->u_nio++; /* we have an I/O in progress! */ 1625 simple_unlock(&uvn->u_obj.vmobjlock); 1626 /* NOTE: object now unlocked */ 1627 if (kva == 0) 1628 kva = uvm_pagermapin(pps, npages, 1629 mapinflags | UVMPAGER_MAPIN_WAITOK); 1630 1631 /* 1632 * ok, mapped in. our pages are PG_BUSY so they are not going to 1633 * get touched (so we can look at "offset" without having to lock 1634 * the object). set up for I/O. 1635 */ 1636 1637 /* 1638 * fill out uio/iov 1639 */ 1640 1641 iov.iov_base = (caddr_t) kva; 1642 wanted = npages << PAGE_SHIFT; 1643 if (file_offset + wanted > uvn->u_size) 1644 wanted = uvn->u_size - file_offset; /* XXX: needed? */ 1645 iov.iov_len = wanted; 1646 uio.uio_iov = &iov; 1647 uio.uio_iovcnt = 1; 1648 uio.uio_offset = file_offset; 1649 uio.uio_segflg = UIO_SYSSPACE; 1650 uio.uio_rw = rw; 1651 uio.uio_resid = wanted; 1652 uio.uio_procp = curproc; 1653 1654 /* 1655 * do the I/O! (XXX: curproc?) 1656 */ 1657 1658 UVMHIST_LOG(maphist, "calling VOP",0,0,0,0); 1659 1660 /* 1661 * This process may already have this vnode locked, if we faulted in 1662 * copyin() or copyout() on a region backed by this vnode 1663 * while doing I/O to the vnode. If this is the case, don't 1664 * panic.. instead, return the error to the user. 1665 * 1666 * XXX this is a stopgap to prevent a panic. 1667 * Ideally, this kind of operation *should* work. 1668 */ 1669 result = 0; 1670 if ((uvn->u_flags & UVM_VNODE_VNISLOCKED) == 0) 1671 result = vn_lock(vn, LK_EXCLUSIVE | LK_RECURSEFAIL, curproc); 1672 1673 if (result == 0) { 1674 /* NOTE: vnode now locked! */ 1675 1676 if (rw == UIO_READ) 1677 result = VOP_READ(vn, &uio, 0, curproc->p_ucred); 1678 else 1679 result = VOP_WRITE(vn, &uio, 0, curproc->p_ucred); 1680 1681 if ((uvn->u_flags & UVM_VNODE_VNISLOCKED) == 0) 1682 VOP_UNLOCK(vn, 0, curproc); 1683 } 1684 1685 /* NOTE: vnode now unlocked (unless vnislocked) */ 1686 1687 UVMHIST_LOG(maphist, "done calling VOP",0,0,0,0); 1688 1689 /* 1690 * result == unix style errno (0 == OK!) 1691 * 1692 * zero out rest of buffer (if needed) 1693 */ 1694 1695 if (result == 0) { 1696 got = wanted - uio.uio_resid; 1697 1698 if (wanted && got == 0) { 1699 result = EIO; /* XXX: error? */ 1700 } else if (got < PAGE_SIZE * npages && rw == UIO_READ) { 1701 memset((void *) (kva + got), 0, 1702 (npages << PAGE_SHIFT) - got); 1703 } 1704 } 1705 1706 /* 1707 * now remove pager mapping 1708 */ 1709 uvm_pagermapout(kva, npages); 1710 1711 /* 1712 * now clean up the object (i.e. drop I/O count) 1713 */ 1714 1715 simple_lock(&uvn->u_obj.vmobjlock); 1716 /* NOTE: object now locked! */ 1717 1718 uvn->u_nio--; /* I/O DONE! */ 1719 if ((uvn->u_flags & UVM_VNODE_IOSYNC) != 0 && uvn->u_nio == 0) { 1720 wakeup(&uvn->u_nio); 1721 } 1722 simple_unlock(&uvn->u_obj.vmobjlock); 1723 /* NOTE: object now unlocked! */ 1724 1725 /* 1726 * done! 1727 */ 1728 1729 UVMHIST_LOG(maphist, "<- done (result %ld)", result,0,0,0); 1730 if (result == 0) 1731 return(VM_PAGER_OK); 1732 else 1733 return(VM_PAGER_ERROR); 1734 } 1735 1736 /* 1737 * uvm_vnp_uncache: disable "persisting" in a vnode... when last reference 1738 * is gone we will kill the object (flushing dirty pages back to the vnode 1739 * if needed). 1740 * 1741 * => returns TRUE if there was no uvm_object attached or if there was 1742 * one and we killed it [i.e. if there is no active uvn] 1743 * => called with the vnode VOP_LOCK'd [we will unlock it for I/O, if 1744 * needed] 1745 * 1746 * => XXX: given that we now kill uvn's when a vnode is recycled (without 1747 * having to hold a reference on the vnode) and given a working 1748 * uvm_vnp_sync(), how does that effect the need for this function? 1749 * [XXXCDC: seems like it can die?] 1750 * 1751 * => XXX: this function should DIE once we merge the VM and buffer 1752 * cache. 1753 * 1754 * research shows that this is called in the following places: 1755 * ext2fs_truncate, ffs_truncate, detrunc[msdosfs]: called when vnode 1756 * changes sizes 1757 * ext2fs_write, WRITE [ufs_readwrite], msdosfs_write: called when we 1758 * are written to 1759 * ex2fs_chmod, ufs_chmod: called if VTEXT vnode and the sticky bit 1760 * is off 1761 * ffs_realloccg: when we can't extend the current block and have 1762 * to allocate a new one we call this [XXX: why?] 1763 * nfsrv_rename, rename_files: called when the target filename is there 1764 * and we want to remove it 1765 * nfsrv_remove, sys_unlink: called on file we are removing 1766 * nfsrv_access: if VTEXT and we want WRITE access and we don't uncache 1767 * then return "text busy" 1768 * nfs_open: seems to uncache any file opened with nfs 1769 * vn_writechk: if VTEXT vnode and can't uncache return "text busy" 1770 */ 1771 1772 boolean_t 1773 uvm_vnp_uncache(vp) 1774 struct vnode *vp; 1775 { 1776 struct uvm_vnode *uvn = &vp->v_uvm; 1777 1778 /* 1779 * lock uvn part of the vnode and check to see if we need to do anything 1780 */ 1781 1782 simple_lock(&uvn->u_obj.vmobjlock); 1783 if ((uvn->u_flags & UVM_VNODE_VALID) == 0 || 1784 (uvn->u_flags & UVM_VNODE_BLOCKED) != 0) { 1785 simple_unlock(&uvn->u_obj.vmobjlock); 1786 return(TRUE); 1787 } 1788 1789 /* 1790 * we have a valid, non-blocked uvn. clear persist flag. 1791 * if uvn is currently active we can return now. 1792 */ 1793 1794 uvn->u_flags &= ~UVM_VNODE_CANPERSIST; 1795 if (uvn->u_obj.uo_refs) { 1796 simple_unlock(&uvn->u_obj.vmobjlock); 1797 return(FALSE); 1798 } 1799 1800 /* 1801 * uvn is currently persisting! we have to gain a reference to 1802 * it so that we can call uvn_detach to kill the uvn. 1803 */ 1804 1805 VREF(vp); /* seems ok, even with VOP_LOCK */ 1806 uvn->u_obj.uo_refs++; /* value is now 1 */ 1807 simple_unlock(&uvn->u_obj.vmobjlock); 1808 1809 1810 #ifdef DEBUG 1811 /* 1812 * carry over sanity check from old vnode pager: the vnode should 1813 * be VOP_LOCK'd, and we confirm it here. 1814 */ 1815 if (!VOP_ISLOCKED(vp)) { 1816 boolean_t is_ok_anyway = FALSE; 1817 #if defined(NFSCLIENT) 1818 extern int (**nfsv2_vnodeop_p)(void *); 1819 extern int (**spec_nfsv2nodeop_p)(void *); 1820 #if defined(FIFO) 1821 extern int (**fifo_nfsv2nodeop_p)(void *); 1822 #endif /* defined(FIFO) */ 1823 1824 /* vnode is NOT VOP_LOCKed: some vnode types _never_ lock */ 1825 if (vp->v_op == nfsv2_vnodeop_p || 1826 vp->v_op == spec_nfsv2nodeop_p) { 1827 is_ok_anyway = TRUE; 1828 } 1829 #if defined(FIFO) 1830 if (vp->v_op == fifo_nfsv2nodeop_p) { 1831 is_ok_anyway = TRUE; 1832 } 1833 #endif /* defined(FIFO) */ 1834 #endif /* defined(NFSSERVER) || defined(NFSCLIENT) */ 1835 if (!is_ok_anyway) 1836 panic("uvm_vnp_uncache: vnode not locked!"); 1837 } 1838 #endif /* DEBUG */ 1839 1840 /* 1841 * now drop our reference to the vnode. if we have the sole 1842 * reference to the vnode then this will cause it to die [as we 1843 * just cleared the persist flag]. we have to unlock the vnode 1844 * while we are doing this as it may trigger I/O. 1845 * 1846 * XXX: it might be possible for uvn to get reclaimed while we are 1847 * unlocked causing us to return TRUE when we should not. we ignore 1848 * this as a false-positive return value doesn't hurt us. 1849 */ 1850 VOP_UNLOCK(vp, 0, curproc); 1851 uvn_detach(&uvn->u_obj); 1852 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, curproc); 1853 1854 /* 1855 * and return... 1856 */ 1857 1858 return(TRUE); 1859 } 1860 1861 /* 1862 * uvm_vnp_setsize: grow or shrink a vnode uvn 1863 * 1864 * grow => just update size value 1865 * shrink => toss un-needed pages 1866 * 1867 * => we assume that the caller has a reference of some sort to the 1868 * vnode in question so that it will not be yanked out from under 1869 * us. 1870 * 1871 * called from: 1872 * => truncate fns (ext2fs_truncate, ffs_truncate, detrunc[msdos]) 1873 * => "write" fns (ext2fs_write, WRITE [ufs/ufs], msdosfs_write, nfs_write) 1874 * => ffs_balloc [XXX: why? doesn't WRITE handle?] 1875 * => NFS: nfs_loadattrcache, nfs_getattrcache, nfs_setattr 1876 * => union fs: union_newsize 1877 */ 1878 1879 void 1880 uvm_vnp_setsize(vp, newsize) 1881 struct vnode *vp; 1882 voff_t newsize; 1883 { 1884 struct uvm_vnode *uvn = &vp->v_uvm; 1885 1886 /* 1887 * lock uvn and check for valid object, and if valid: do it! 1888 */ 1889 simple_lock(&uvn->u_obj.vmobjlock); 1890 if (uvn->u_flags & UVM_VNODE_VALID) { 1891 1892 /* 1893 * now check if the size has changed: if we shrink we had better 1894 * toss some pages... 1895 */ 1896 1897 if (uvn->u_size > newsize) { 1898 (void)uvn_flush(&uvn->u_obj, newsize, 1899 uvn->u_size, PGO_FREE); 1900 } 1901 uvn->u_size = newsize; 1902 } 1903 simple_unlock(&uvn->u_obj.vmobjlock); 1904 1905 /* 1906 * done 1907 */ 1908 return; 1909 } 1910 1911 /* 1912 * uvm_vnp_sync: flush all dirty VM pages back to their backing vnodes. 1913 * 1914 * => called from sys_sync with no VM structures locked 1915 * => only one process can do a sync at a time (because the uvn 1916 * structure only has one queue for sync'ing). we ensure this 1917 * by holding the uvn_sync_lock while the sync is in progress. 1918 * other processes attempting a sync will sleep on this lock 1919 * until we are done. 1920 */ 1921 1922 void 1923 uvm_vnp_sync(mp) 1924 struct mount *mp; 1925 { 1926 struct uvm_vnode *uvn; 1927 struct vnode *vp; 1928 boolean_t got_lock; 1929 1930 /* 1931 * step 1: ensure we are only ones using the uvn_sync_q by locking 1932 * our lock... 1933 */ 1934 rw_enter_write(&uvn_sync_lock); 1935 1936 /* 1937 * step 2: build up a simpleq of uvns of interest based on the 1938 * write list. we gain a reference to uvns of interest. must 1939 * be careful about locking uvn's since we will be holding uvn_wl_lock 1940 * in the body of the loop. 1941 */ 1942 SIMPLEQ_INIT(&uvn_sync_q); 1943 simple_lock(&uvn_wl_lock); 1944 LIST_FOREACH(uvn, &uvn_wlist, u_wlist) { 1945 1946 vp = (struct vnode *) uvn; 1947 if (mp && vp->v_mount != mp) 1948 continue; 1949 1950 /* attempt to gain reference */ 1951 while ((got_lock = simple_lock_try(&uvn->u_obj.vmobjlock)) == 1952 FALSE && 1953 (uvn->u_flags & UVM_VNODE_BLOCKED) == 0) 1954 /* spin */; 1955 1956 /* 1957 * we will exit the loop if either if the following are true: 1958 * - we got the lock [always true if NCPU == 1] 1959 * - we failed to get the lock but noticed the vnode was 1960 * "blocked" -- in this case the vnode must be a dying 1961 * vnode, and since dying vnodes are in the process of 1962 * being flushed out, we can safely skip this one 1963 * 1964 * we want to skip over the vnode if we did not get the lock, 1965 * or if the vnode is already dying (due to the above logic). 1966 * 1967 * note that uvn must already be valid because we found it on 1968 * the wlist (this also means it can't be ALOCK'd). 1969 */ 1970 if (!got_lock || (uvn->u_flags & UVM_VNODE_BLOCKED) != 0) { 1971 if (got_lock) 1972 simple_unlock(&uvn->u_obj.vmobjlock); 1973 continue; /* skip it */ 1974 } 1975 1976 /* 1977 * gain reference. watch out for persisting uvns (need to 1978 * regain vnode REF). 1979 */ 1980 if (uvn->u_obj.uo_refs == 0) 1981 VREF(vp); 1982 uvn->u_obj.uo_refs++; 1983 simple_unlock(&uvn->u_obj.vmobjlock); 1984 1985 /* 1986 * got it! 1987 */ 1988 SIMPLEQ_INSERT_HEAD(&uvn_sync_q, uvn, u_syncq); 1989 } 1990 simple_unlock(&uvn_wl_lock); 1991 1992 /* 1993 * step 3: we now have a list of uvn's that may need cleaning. 1994 * we are holding the uvn_sync_lock, but have dropped the uvn_wl_lock 1995 * (so we can now safely lock uvn's again). 1996 */ 1997 1998 SIMPLEQ_FOREACH(uvn, &uvn_sync_q, u_syncq) { 1999 simple_lock(&uvn->u_obj.vmobjlock); 2000 #ifdef DEBUG 2001 if (uvn->u_flags & UVM_VNODE_DYING) { 2002 printf("uvm_vnp_sync: dying vnode on sync list\n"); 2003 } 2004 #endif 2005 uvn_flush(&uvn->u_obj, 0, 0, 2006 PGO_CLEANIT|PGO_ALLPAGES|PGO_DOACTCLUST); 2007 2008 /* 2009 * if we have the only reference and we just cleaned the uvn, 2010 * then we can pull it out of the UVM_VNODE_WRITEABLE state 2011 * thus allowing us to avoid thinking about flushing it again 2012 * on later sync ops. 2013 */ 2014 if (uvn->u_obj.uo_refs == 1 && 2015 (uvn->u_flags & UVM_VNODE_WRITEABLE)) { 2016 LIST_REMOVE(uvn, u_wlist); 2017 uvn->u_flags &= ~UVM_VNODE_WRITEABLE; 2018 } 2019 2020 simple_unlock(&uvn->u_obj.vmobjlock); 2021 2022 /* now drop our reference to the uvn */ 2023 uvn_detach(&uvn->u_obj); 2024 } 2025 2026 /* 2027 * done! release sync lock 2028 */ 2029 rw_exit_write(&uvn_sync_lock); 2030 } 2031