xref: /netbsd-src/sys/miscfs/genfs/genfs_io.c (revision e6c7e151de239c49d2e38720a061ed9d1fa99309)
1 /*	$NetBSD: genfs_io.c,v 1.95 2020/03/22 18:32:41 ad Exp $	*/
2 
3 /*
4  * Copyright (c) 1982, 1986, 1989, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  */
32 
33 #include <sys/cdefs.h>
34 __KERNEL_RCSID(0, "$NetBSD: genfs_io.c,v 1.95 2020/03/22 18:32:41 ad Exp $");
35 
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/proc.h>
39 #include <sys/kernel.h>
40 #include <sys/mount.h>
41 #include <sys/vnode.h>
42 #include <sys/kmem.h>
43 #include <sys/kauth.h>
44 #include <sys/fstrans.h>
45 #include <sys/buf.h>
46 #include <sys/atomic.h>
47 
48 #include <miscfs/genfs/genfs.h>
49 #include <miscfs/genfs/genfs_node.h>
50 #include <miscfs/specfs/specdev.h>
51 
52 #include <uvm/uvm.h>
53 #include <uvm/uvm_pager.h>
54 #include <uvm/uvm_page_array.h>
55 
56 static int genfs_do_directio(struct vmspace *, vaddr_t, size_t, struct vnode *,
57     off_t, enum uio_rw);
58 static void genfs_dio_iodone(struct buf *);
59 
60 static int genfs_getpages_read(struct vnode *, struct vm_page **, int, off_t,
61     off_t, bool, bool, bool, bool);
62 static int genfs_do_io(struct vnode *, off_t, vaddr_t, size_t, int, enum uio_rw,
63     void (*)(struct buf *));
64 static void genfs_rel_pages(struct vm_page **, unsigned int);
65 
66 int genfs_maxdio = MAXPHYS;
67 
68 static void
69 genfs_rel_pages(struct vm_page **pgs, unsigned int npages)
70 {
71 	unsigned int i;
72 
73 	for (i = 0; i < npages; i++) {
74 		struct vm_page *pg = pgs[i];
75 
76 		if (pg == NULL || pg == PGO_DONTCARE)
77 			continue;
78 		KASSERT(uvm_page_owner_locked_p(pg, true));
79 		if (pg->flags & PG_FAKE) {
80 			pg->flags |= PG_RELEASED;
81 		}
82 	}
83 	uvm_page_unbusy(pgs, npages);
84 }
85 
86 /*
87  * generic VM getpages routine.
88  * Return PG_BUSY pages for the given range,
89  * reading from backing store if necessary.
90  */
91 
92 int
93 genfs_getpages(void *v)
94 {
95 	struct vop_getpages_args /* {
96 		struct vnode *a_vp;
97 		voff_t a_offset;
98 		struct vm_page **a_m;
99 		int *a_count;
100 		int a_centeridx;
101 		vm_prot_t a_access_type;
102 		int a_advice;
103 		int a_flags;
104 	} */ * const ap = v;
105 
106 	off_t diskeof, memeof;
107 	int i, error, npages, iflag;
108 	const int flags = ap->a_flags;
109 	struct vnode * const vp = ap->a_vp;
110 	struct uvm_object * const uobj = &vp->v_uobj;
111 	const bool async = (flags & PGO_SYNCIO) == 0;
112 	const bool memwrite = (ap->a_access_type & VM_PROT_WRITE) != 0;
113 	const bool overwrite = (flags & PGO_OVERWRITE) != 0;
114 	const bool blockalloc = memwrite && (flags & PGO_NOBLOCKALLOC) == 0;
115 	const bool need_wapbl = (vp->v_mount->mnt_wapbl &&
116 			(flags & PGO_JOURNALLOCKED) == 0);
117 	const bool glocked = (flags & PGO_GLOCKHELD) != 0;
118 	bool holds_wapbl = false;
119 	struct mount *trans_mount = NULL;
120 	UVMHIST_FUNC("genfs_getpages"); UVMHIST_CALLED(ubchist);
121 
122 	UVMHIST_LOG(ubchist, "vp %#jx off 0x%jx/%jx count %jd",
123 	    (uintptr_t)vp, ap->a_offset >> 32, ap->a_offset, *ap->a_count);
124 
125 	KASSERT(memwrite >= overwrite);
126 	KASSERT(vp->v_type == VREG || vp->v_type == VDIR ||
127 	    vp->v_type == VLNK || vp->v_type == VBLK);
128 
129 	/*
130 	 * the object must be locked.  it can only be a read lock when
131 	 * processing a read fault with PGO_LOCKED | PGO_NOBUSY.
132 	 */
133 
134 	KASSERT(rw_lock_held(uobj->vmobjlock));
135 	KASSERT(rw_write_held(uobj->vmobjlock) ||
136 	   ((~flags & (PGO_LOCKED | PGO_NOBUSY)) == 0 && !memwrite));
137 
138 #ifdef DIAGNOSTIC
139 	if ((flags & PGO_JOURNALLOCKED) && vp->v_mount->mnt_wapbl)
140                 WAPBL_JLOCK_ASSERT(vp->v_mount);
141 #endif
142 
143 	/*
144 	 * check for reclaimed vnode.  v_interlock is not held here, but
145 	 * VI_DEADCHECK is set with vmobjlock held.
146 	 */
147 
148 	iflag = atomic_load_relaxed(&vp->v_iflag);
149 	if (__predict_false((iflag & VI_DEADCHECK) != 0)) {
150 		mutex_enter(vp->v_interlock);
151 		error = vdead_check(vp, VDEAD_NOWAIT);
152 		mutex_exit(vp->v_interlock);
153 		if (error) {
154 			if ((flags & PGO_LOCKED) == 0)
155 				rw_exit(uobj->vmobjlock);
156 			return error;
157 		}
158 	}
159 
160 startover:
161 	error = 0;
162 	const voff_t origvsize = vp->v_size;
163 	const off_t origoffset = ap->a_offset;
164 	const int orignpages = *ap->a_count;
165 
166 	GOP_SIZE(vp, origvsize, &diskeof, 0);
167 	if (flags & PGO_PASTEOF) {
168 		off_t newsize;
169 #if defined(DIAGNOSTIC)
170 		off_t writeeof;
171 #endif /* defined(DIAGNOSTIC) */
172 
173 		newsize = MAX(origvsize,
174 		    origoffset + (orignpages << PAGE_SHIFT));
175 		GOP_SIZE(vp, newsize, &memeof, GOP_SIZE_MEM);
176 #if defined(DIAGNOSTIC)
177 		GOP_SIZE(vp, vp->v_writesize, &writeeof, GOP_SIZE_MEM);
178 		if (newsize > round_page(writeeof)) {
179 			panic("%s: past eof: %" PRId64 " vs. %" PRId64,
180 			    __func__, newsize, round_page(writeeof));
181 		}
182 #endif /* defined(DIAGNOSTIC) */
183 	} else {
184 		GOP_SIZE(vp, origvsize, &memeof, GOP_SIZE_MEM);
185 	}
186 	KASSERT(ap->a_centeridx >= 0 || ap->a_centeridx <= orignpages);
187 	KASSERT((origoffset & (PAGE_SIZE - 1)) == 0 && origoffset >= 0);
188 	KASSERT(orignpages > 0);
189 
190 	/*
191 	 * Bounds-check the request.
192 	 */
193 
194 	if (origoffset + (ap->a_centeridx << PAGE_SHIFT) >= memeof) {
195 		if ((flags & PGO_LOCKED) == 0) {
196 			rw_exit(uobj->vmobjlock);
197 		}
198 		UVMHIST_LOG(ubchist, "off 0x%jx count %jd goes past EOF 0x%jx",
199 		    origoffset, *ap->a_count, memeof,0);
200 		error = EINVAL;
201 		goto out_err;
202 	}
203 
204 	/* uobj is locked */
205 
206 	if ((flags & PGO_NOTIMESTAMP) == 0 &&
207 	    (vp->v_type != VBLK ||
208 	    (vp->v_mount->mnt_flag & MNT_NODEVMTIME) == 0)) {
209 		int updflags = 0;
210 
211 		if ((vp->v_mount->mnt_flag & MNT_NOATIME) == 0) {
212 			updflags = GOP_UPDATE_ACCESSED;
213 		}
214 		if (memwrite) {
215 			updflags |= GOP_UPDATE_MODIFIED;
216 		}
217 		if (updflags != 0) {
218 			GOP_MARKUPDATE(vp, updflags);
219 		}
220 	}
221 
222 	/*
223 	 * For PGO_LOCKED requests, just return whatever's in memory.
224 	 */
225 
226 	if (flags & PGO_LOCKED) {
227 		int nfound;
228 		struct vm_page *pg;
229 
230 		KASSERT(!glocked);
231 		npages = *ap->a_count;
232 #if defined(DEBUG)
233 		for (i = 0; i < npages; i++) {
234 			pg = ap->a_m[i];
235 			KASSERT(pg == NULL || pg == PGO_DONTCARE);
236 		}
237 #endif /* defined(DEBUG) */
238  		nfound = uvn_findpages(uobj, origoffset, &npages,
239 		    ap->a_m, NULL,
240 		    UFP_NOWAIT | UFP_NOALLOC |
241 		    (memwrite ? UFP_NORDONLY : 0) |
242 		    ((flags & PGO_NOBUSY) != 0 ? UFP_NOBUSY : 0));
243 		KASSERT(npages == *ap->a_count);
244 		if (nfound == 0) {
245 			error = EBUSY;
246 			goto out_err;
247 		}
248 		/*
249 		 * lock and unlock g_glock to ensure that no one is truncating
250 		 * the file behind us.
251 		 */
252 		if (!genfs_node_rdtrylock(vp)) {
253 			if ((flags & PGO_NOBUSY) == 0) {
254 				genfs_rel_pages(ap->a_m, npages);
255 			}
256 
257 			/*
258 			 * restore the array.
259 			 */
260 
261 			for (i = 0; i < npages; i++) {
262 				pg = ap->a_m[i];
263 
264 				if (pg != NULL && pg != PGO_DONTCARE) {
265 					ap->a_m[i] = NULL;
266 				}
267 				KASSERT(ap->a_m[i] == NULL ||
268 				    ap->a_m[i] == PGO_DONTCARE);
269 			}
270 		} else {
271 			genfs_node_unlock(vp);
272 		}
273 		error = (ap->a_m[ap->a_centeridx] == NULL ? EBUSY : 0);
274 		if (error == 0 && memwrite) {
275 			for (i = 0; i < npages; i++) {
276 				pg = ap->a_m[i];
277 				if (pg == NULL || pg == PGO_DONTCARE) {
278 					continue;
279 				}
280 				if (uvm_pagegetdirty(pg) ==
281 				    UVM_PAGE_STATUS_CLEAN) {
282 					uvm_pagemarkdirty(pg,
283 					    UVM_PAGE_STATUS_UNKNOWN);
284 				}
285 			}
286 		}
287 		goto out_err;
288 	}
289 	rw_exit(uobj->vmobjlock);
290 
291 	/*
292 	 * find the requested pages and make some simple checks.
293 	 * leave space in the page array for a whole block.
294 	 */
295 
296 	const int fs_bshift = (vp->v_type != VBLK) ?
297 	    vp->v_mount->mnt_fs_bshift : DEV_BSHIFT;
298 	const int fs_bsize = 1 << fs_bshift;
299 #define	blk_mask	(fs_bsize - 1)
300 #define	trunc_blk(x)	((x) & ~blk_mask)
301 #define	round_blk(x)	(((x) + blk_mask) & ~blk_mask)
302 
303 	const int orignmempages = MIN(orignpages,
304 	    round_page(memeof - origoffset) >> PAGE_SHIFT);
305 	npages = orignmempages;
306 	const off_t startoffset = trunc_blk(origoffset);
307 	const off_t endoffset = MIN(
308 	    round_page(round_blk(origoffset + (npages << PAGE_SHIFT))),
309 	    round_page(memeof));
310 	const int ridx = (origoffset - startoffset) >> PAGE_SHIFT;
311 
312 	const int pgs_size = sizeof(struct vm_page *) *
313 	    ((endoffset - startoffset) >> PAGE_SHIFT);
314 	struct vm_page **pgs, *pgs_onstack[UBC_MAX_PAGES];
315 
316 	if (pgs_size > sizeof(pgs_onstack)) {
317 		pgs = kmem_zalloc(pgs_size, async ? KM_NOSLEEP : KM_SLEEP);
318 		if (pgs == NULL) {
319 			pgs = pgs_onstack;
320 			error = ENOMEM;
321 			goto out_err;
322 		}
323 	} else {
324 		pgs = pgs_onstack;
325 		(void)memset(pgs, 0, pgs_size);
326 	}
327 
328 	UVMHIST_LOG(ubchist, "ridx %jd npages %jd startoff %jd endoff %jd",
329 	    ridx, npages, startoffset, endoffset);
330 
331 	if (trans_mount == NULL) {
332 		trans_mount = vp->v_mount;
333 		fstrans_start(trans_mount);
334 		/*
335 		 * check if this vnode is still valid.
336 		 */
337 		mutex_enter(vp->v_interlock);
338 		error = vdead_check(vp, 0);
339 		mutex_exit(vp->v_interlock);
340 		if (error)
341 			goto out_err_free;
342 		/*
343 		 * XXX: This assumes that we come here only via
344 		 * the mmio path
345 		 */
346 		if (blockalloc && need_wapbl) {
347 			error = WAPBL_BEGIN(trans_mount);
348 			if (error)
349 				goto out_err_free;
350 			holds_wapbl = true;
351 		}
352 	}
353 
354 	/*
355 	 * hold g_glock to prevent a race with truncate.
356 	 *
357 	 * check if our idea of v_size is still valid.
358 	 */
359 
360 	KASSERT(!glocked || genfs_node_wrlocked(vp));
361 	if (!glocked) {
362 		if (blockalloc) {
363 			genfs_node_wrlock(vp);
364 		} else {
365 			genfs_node_rdlock(vp);
366 		}
367 	}
368 	rw_enter(uobj->vmobjlock, RW_WRITER);
369 	if (vp->v_size < origvsize) {
370 		if (!glocked) {
371 			genfs_node_unlock(vp);
372 		}
373 		if (pgs != pgs_onstack)
374 			kmem_free(pgs, pgs_size);
375 		goto startover;
376 	}
377 
378 	if (uvn_findpages(uobj, origoffset, &npages, &pgs[ridx], NULL,
379 	    async ? UFP_NOWAIT : UFP_ALL) != orignmempages) {
380 		if (!glocked) {
381 			genfs_node_unlock(vp);
382 		}
383 		KASSERT(async != 0);
384 		genfs_rel_pages(&pgs[ridx], orignmempages);
385 		rw_exit(uobj->vmobjlock);
386 		error = EBUSY;
387 		goto out_err_free;
388 	}
389 
390 	/*
391 	 * if PGO_OVERWRITE is set, don't bother reading the pages.
392 	 */
393 
394 	if (overwrite) {
395 		if (!glocked) {
396 			genfs_node_unlock(vp);
397 		}
398 		UVMHIST_LOG(ubchist, "PGO_OVERWRITE",0,0,0,0);
399 
400 		for (i = 0; i < npages; i++) {
401 			struct vm_page *pg = pgs[ridx + i];
402 
403 			/*
404 			 * it's caller's responsibility to allocate blocks
405 			 * beforehand for the overwrite case.
406 			 */
407 
408 			KASSERT((pg->flags & PG_RDONLY) == 0 || !blockalloc);
409 			pg->flags &= ~PG_RDONLY;
410 
411 			/*
412 			 * mark the page DIRTY.
413 			 * otherwise another thread can do putpages and pull
414 			 * our vnode from syncer's queue before our caller does
415 			 * ubc_release.  note that putpages won't see CLEAN
416 			 * pages even if they are BUSY.
417 			 */
418 
419 			uvm_pagemarkdirty(pg, UVM_PAGE_STATUS_DIRTY);
420 		}
421 		npages += ridx;
422 		goto out;
423 	}
424 
425 	/*
426 	 * if the pages are already resident, just return them.
427 	 */
428 
429 	for (i = 0; i < npages; i++) {
430 		struct vm_page *pg = pgs[ridx + i];
431 
432 		if ((pg->flags & PG_FAKE) ||
433 		    (blockalloc && (pg->flags & PG_RDONLY) != 0)) {
434 			break;
435 		}
436 	}
437 	if (i == npages) {
438 		if (!glocked) {
439 			genfs_node_unlock(vp);
440 		}
441 		UVMHIST_LOG(ubchist, "returning cached pages", 0,0,0,0);
442 		npages += ridx;
443 		goto out;
444 	}
445 
446 	/*
447 	 * the page wasn't resident and we're not overwriting,
448 	 * so we're going to have to do some i/o.
449 	 * find any additional pages needed to cover the expanded range.
450 	 */
451 
452 	npages = (endoffset - startoffset) >> PAGE_SHIFT;
453 	if (startoffset != origoffset || npages != orignmempages) {
454 		int npgs;
455 
456 		/*
457 		 * we need to avoid deadlocks caused by locking
458 		 * additional pages at lower offsets than pages we
459 		 * already have locked.  unlock them all and start over.
460 		 */
461 
462 		genfs_rel_pages(&pgs[ridx], orignmempages);
463 		memset(pgs, 0, pgs_size);
464 
465 		UVMHIST_LOG(ubchist, "reset npages start 0x%jx end 0x%jx",
466 		    startoffset, endoffset, 0,0);
467 		npgs = npages;
468 		if (uvn_findpages(uobj, startoffset, &npgs, pgs, NULL,
469 		    async ? UFP_NOWAIT : UFP_ALL) != npages) {
470 			if (!glocked) {
471 				genfs_node_unlock(vp);
472 			}
473 			KASSERT(async != 0);
474 			genfs_rel_pages(pgs, npages);
475 			rw_exit(uobj->vmobjlock);
476 			error = EBUSY;
477 			goto out_err_free;
478 		}
479 	}
480 
481 	rw_exit(uobj->vmobjlock);
482 	error = genfs_getpages_read(vp, pgs, npages, startoffset, diskeof,
483 	    async, memwrite, blockalloc, glocked);
484 	if (!glocked) {
485 		genfs_node_unlock(vp);
486 	}
487 	if (error == 0 && async)
488 		goto out_err_free;
489 	rw_enter(uobj->vmobjlock, RW_WRITER);
490 
491 	/*
492 	 * we're almost done!  release the pages...
493 	 * for errors, we free the pages.
494 	 * otherwise we activate them and mark them as valid and clean.
495 	 * also, unbusy pages that were not actually requested.
496 	 */
497 
498 	if (error) {
499 		genfs_rel_pages(pgs, npages);
500 		rw_exit(uobj->vmobjlock);
501 		UVMHIST_LOG(ubchist, "returning error %jd", error,0,0,0);
502 		goto out_err_free;
503 	}
504 
505 out:
506 	UVMHIST_LOG(ubchist, "succeeding, npages %jd", npages,0,0,0);
507 	error = 0;
508 	for (i = 0; i < npages; i++) {
509 		struct vm_page *pg = pgs[i];
510 		if (pg == NULL) {
511 			continue;
512 		}
513 		UVMHIST_LOG(ubchist, "examining pg %#jx flags 0x%jx",
514 		    (uintptr_t)pg, pg->flags, 0,0);
515 		if (pg->flags & PG_FAKE && !overwrite) {
516 			/*
517 			 * we've read page's contents from the backing storage.
518 			 *
519 			 * for a read fault, we keep them CLEAN;  if we
520 			 * encountered a hole while reading, the pages can
521 			 * already been dirtied with zeros.
522 			 */
523 			KASSERTMSG(blockalloc || uvm_pagegetdirty(pg) ==
524 			    UVM_PAGE_STATUS_CLEAN, "page %p not clean", pg);
525 			pg->flags &= ~PG_FAKE;
526 		}
527 		KASSERT(!memwrite || !blockalloc || (pg->flags & PG_RDONLY) == 0);
528 		if (i < ridx || i >= ridx + orignmempages || async) {
529 			UVMHIST_LOG(ubchist, "unbusy pg %#jx offset 0x%jx",
530 			    (uintptr_t)pg, pg->offset,0,0);
531 			if (pg->flags & PG_FAKE) {
532 				KASSERT(overwrite);
533 				uvm_pagezero(pg);
534 			}
535 			if (pg->flags & PG_RELEASED) {
536 				uvm_pagefree(pg);
537 				continue;
538 			}
539 			uvm_pagelock(pg);
540 			uvm_pageenqueue(pg);
541 			uvm_pagewakeup(pg);
542 			uvm_pageunlock(pg);
543 			pg->flags &= ~(PG_BUSY|PG_FAKE);
544 			UVM_PAGE_OWN(pg, NULL);
545 		} else if (memwrite && !overwrite &&
546 		    uvm_pagegetdirty(pg) == UVM_PAGE_STATUS_CLEAN) {
547 			/*
548 			 * for a write fault, start dirtiness tracking of
549 			 * requested pages.
550 			 */
551 			uvm_pagemarkdirty(pg, UVM_PAGE_STATUS_UNKNOWN);
552 		}
553 	}
554 	rw_exit(uobj->vmobjlock);
555 	if (ap->a_m != NULL) {
556 		memcpy(ap->a_m, &pgs[ridx],
557 		    orignmempages * sizeof(struct vm_page *));
558 	}
559 
560 out_err_free:
561 	if (pgs != NULL && pgs != pgs_onstack)
562 		kmem_free(pgs, pgs_size);
563 out_err:
564 	if (trans_mount != NULL) {
565 		if (holds_wapbl)
566 			WAPBL_END(trans_mount);
567 		fstrans_done(trans_mount);
568 	}
569 	return error;
570 }
571 
572 /*
573  * genfs_getpages_read: Read the pages in with VOP_BMAP/VOP_STRATEGY.
574  *
575  * "glocked" (which is currently not actually used) tells us not whether
576  * the genfs_node is locked on entry (it always is) but whether it was
577  * locked on entry to genfs_getpages.
578  */
579 static int
580 genfs_getpages_read(struct vnode *vp, struct vm_page **pgs, int npages,
581     off_t startoffset, off_t diskeof,
582     bool async, bool memwrite, bool blockalloc, bool glocked)
583 {
584 	struct uvm_object * const uobj = &vp->v_uobj;
585 	const int fs_bshift = (vp->v_type != VBLK) ?
586 	    vp->v_mount->mnt_fs_bshift : DEV_BSHIFT;
587 	const int dev_bshift = (vp->v_type != VBLK) ?
588 	    vp->v_mount->mnt_dev_bshift : DEV_BSHIFT;
589 	kauth_cred_t const cred = curlwp->l_cred;		/* XXXUBC curlwp */
590 	size_t bytes, iobytes, tailstart, tailbytes, totalbytes, skipbytes;
591 	vaddr_t kva;
592 	struct buf *bp, *mbp;
593 	bool sawhole = false;
594 	int i;
595 	int error = 0;
596 
597 	UVMHIST_FUNC(__func__); UVMHIST_CALLED(ubchist);
598 
599 	/*
600 	 * read the desired page(s).
601 	 */
602 
603 	totalbytes = npages << PAGE_SHIFT;
604 	bytes = MIN(totalbytes, MAX(diskeof - startoffset, 0));
605 	tailbytes = totalbytes - bytes;
606 	skipbytes = 0;
607 
608 	kva = uvm_pagermapin(pgs, npages,
609 	    UVMPAGER_MAPIN_READ | (async ? 0 : UVMPAGER_MAPIN_WAITOK));
610 	if (kva == 0)
611 		return EBUSY;
612 
613 	mbp = getiobuf(vp, true);
614 	mbp->b_bufsize = totalbytes;
615 	mbp->b_data = (void *)kva;
616 	mbp->b_resid = mbp->b_bcount = bytes;
617 	mbp->b_cflags |= BC_BUSY;
618 	if (async) {
619 		mbp->b_flags = B_READ | B_ASYNC;
620 		mbp->b_iodone = uvm_aio_aiodone;
621 	} else {
622 		mbp->b_flags = B_READ;
623 		mbp->b_iodone = NULL;
624 	}
625 	if (async)
626 		BIO_SETPRIO(mbp, BPRIO_TIMELIMITED);
627 	else
628 		BIO_SETPRIO(mbp, BPRIO_TIMECRITICAL);
629 
630 	/*
631 	 * if EOF is in the middle of the range, zero the part past EOF.
632 	 * skip over pages which are not PG_FAKE since in that case they have
633 	 * valid data that we need to preserve.
634 	 */
635 
636 	tailstart = bytes;
637 	while (tailbytes > 0) {
638 		const int len = PAGE_SIZE - (tailstart & PAGE_MASK);
639 
640 		KASSERT(len <= tailbytes);
641 		if ((pgs[tailstart >> PAGE_SHIFT]->flags & PG_FAKE) != 0) {
642 			memset((void *)(kva + tailstart), 0, len);
643 			UVMHIST_LOG(ubchist, "tailbytes %#jx 0x%jx 0x%jx",
644 			    (uintptr_t)kva, tailstart, len, 0);
645 		}
646 		tailstart += len;
647 		tailbytes -= len;
648 	}
649 
650 	/*
651 	 * now loop over the pages, reading as needed.
652 	 */
653 
654 	bp = NULL;
655 	off_t offset;
656 	for (offset = startoffset;
657 	    bytes > 0;
658 	    offset += iobytes, bytes -= iobytes) {
659 		int run;
660 		daddr_t lbn, blkno;
661 		int pidx;
662 		struct vnode *devvp;
663 
664 		/*
665 		 * skip pages which don't need to be read.
666 		 */
667 
668 		pidx = (offset - startoffset) >> PAGE_SHIFT;
669 		while ((pgs[pidx]->flags & PG_FAKE) == 0) {
670 			size_t b;
671 
672 			KASSERT((offset & (PAGE_SIZE - 1)) == 0);
673 			if ((pgs[pidx]->flags & PG_RDONLY)) {
674 				sawhole = true;
675 			}
676 			b = MIN(PAGE_SIZE, bytes);
677 			offset += b;
678 			bytes -= b;
679 			skipbytes += b;
680 			pidx++;
681 			UVMHIST_LOG(ubchist, "skipping, new offset 0x%jx",
682 			    offset, 0,0,0);
683 			if (bytes == 0) {
684 				goto loopdone;
685 			}
686 		}
687 
688 		/*
689 		 * bmap the file to find out the blkno to read from and
690 		 * how much we can read in one i/o.  if bmap returns an error,
691 		 * skip the rest of the top-level i/o.
692 		 */
693 
694 		lbn = offset >> fs_bshift;
695 		error = VOP_BMAP(vp, lbn, &devvp, &blkno, &run);
696 		if (error) {
697 			UVMHIST_LOG(ubchist, "VOP_BMAP lbn 0x%jx -> %jd\n",
698 			    lbn,error,0,0);
699 			skipbytes += bytes;
700 			bytes = 0;
701 			goto loopdone;
702 		}
703 
704 		/*
705 		 * see how many pages can be read with this i/o.
706 		 * reduce the i/o size if necessary to avoid
707 		 * overwriting pages with valid data.
708 		 */
709 
710 		iobytes = MIN((((off_t)lbn + 1 + run) << fs_bshift) - offset,
711 		    bytes);
712 		if (offset + iobytes > round_page(offset)) {
713 			int pcount;
714 
715 			pcount = 1;
716 			while (pidx + pcount < npages &&
717 			    pgs[pidx + pcount]->flags & PG_FAKE) {
718 				pcount++;
719 			}
720 			iobytes = MIN(iobytes, (pcount << PAGE_SHIFT) -
721 			    (offset - trunc_page(offset)));
722 		}
723 
724 		/*
725 		 * if this block isn't allocated, zero it instead of
726 		 * reading it.  unless we are going to allocate blocks,
727 		 * mark the pages we zeroed PG_RDONLY.
728 		 */
729 
730 		if (blkno == (daddr_t)-1) {
731 			int holepages = (round_page(offset + iobytes) -
732 			    trunc_page(offset)) >> PAGE_SHIFT;
733 			UVMHIST_LOG(ubchist, "lbn 0x%jx -> HOLE", lbn,0,0,0);
734 
735 			sawhole = true;
736 			memset((char *)kva + (offset - startoffset), 0,
737 			    iobytes);
738 			skipbytes += iobytes;
739 
740 			if (!blockalloc) {
741 				rw_enter(uobj->vmobjlock, RW_WRITER);
742 				for (i = 0; i < holepages; i++) {
743 					pgs[pidx + i]->flags |= PG_RDONLY;
744 				}
745 				rw_exit(uobj->vmobjlock);
746 			}
747 			continue;
748 		}
749 
750 		/*
751 		 * allocate a sub-buf for this piece of the i/o
752 		 * (or just use mbp if there's only 1 piece),
753 		 * and start it going.
754 		 */
755 
756 		if (offset == startoffset && iobytes == bytes) {
757 			bp = mbp;
758 		} else {
759 			UVMHIST_LOG(ubchist, "vp %#jx bp %#jx num now %jd",
760 			    (uintptr_t)vp, (uintptr_t)bp, vp->v_numoutput, 0);
761 			bp = getiobuf(vp, true);
762 			nestiobuf_setup(mbp, bp, offset - startoffset, iobytes);
763 		}
764 		bp->b_lblkno = 0;
765 
766 		/* adjust physical blkno for partial blocks */
767 		bp->b_blkno = blkno + ((offset - ((off_t)lbn << fs_bshift)) >>
768 		    dev_bshift);
769 
770 		UVMHIST_LOG(ubchist,
771 		    "bp %#jx offset 0x%x bcount 0x%x blkno 0x%x",
772 		    (uintptr_t)bp, offset, bp->b_bcount, bp->b_blkno);
773 
774 		VOP_STRATEGY(devvp, bp);
775 	}
776 
777 loopdone:
778 	nestiobuf_done(mbp, skipbytes, error);
779 	if (async) {
780 		UVMHIST_LOG(ubchist, "returning 0 (async)",0,0,0,0);
781 		return 0;
782 	}
783 	if (bp != NULL) {
784 		error = biowait(mbp);
785 	}
786 
787 	/* Remove the mapping (make KVA available as soon as possible) */
788 	uvm_pagermapout(kva, npages);
789 
790 	/*
791 	 * if this we encountered a hole then we have to do a little more work.
792 	 * for read faults, we marked the page PG_RDONLY so that future
793 	 * write accesses to the page will fault again.
794 	 * for write faults, we must make sure that the backing store for
795 	 * the page is completely allocated while the pages are locked.
796 	 */
797 
798 	if (!error && sawhole && blockalloc) {
799 		error = GOP_ALLOC(vp, startoffset,
800 		    npages << PAGE_SHIFT, 0, cred);
801 		UVMHIST_LOG(ubchist, "gop_alloc off 0x%jx/0x%jx -> %jd",
802 		    startoffset, npages << PAGE_SHIFT, error,0);
803 		if (!error) {
804 			rw_enter(uobj->vmobjlock, RW_WRITER);
805 			for (i = 0; i < npages; i++) {
806 				struct vm_page *pg = pgs[i];
807 
808 				if (pg == NULL) {
809 					continue;
810 				}
811 				pg->flags &= ~PG_RDONLY;
812 				uvm_pagemarkdirty(pg, UVM_PAGE_STATUS_DIRTY);
813 				UVMHIST_LOG(ubchist, "mark dirty pg %#jx",
814 				    (uintptr_t)pg, 0, 0, 0);
815 			}
816 			rw_exit(uobj->vmobjlock);
817 		}
818 	}
819 
820 	putiobuf(mbp);
821 	return error;
822 }
823 
824 /*
825  * generic VM putpages routine.
826  * Write the given range of pages to backing store.
827  *
828  * => "offhi == 0" means flush all pages at or after "offlo".
829  * => object should be locked by caller.  we return with the
830  *      object unlocked.
831  * => if PGO_CLEANIT or PGO_SYNCIO is set, we may block (due to I/O).
832  *	thus, a caller might want to unlock higher level resources
833  *	(e.g. vm_map) before calling flush.
834  * => if neither PGO_CLEANIT nor PGO_SYNCIO is set, we will not block
835  * => if PGO_ALLPAGES is set, then all pages in the object will be processed.
836  *
837  * note on "cleaning" object and PG_BUSY pages:
838  *	this routine is holding the lock on the object.   the only time
839  *	that it can run into a PG_BUSY page that it does not own is if
840  *	some other process has started I/O on the page (e.g. either
841  *	a pagein, or a pageout).  if the PG_BUSY page is being paged
842  *	in, then it can not be dirty (!UVM_PAGE_STATUS_CLEAN) because no
843  *	one has	had a chance to modify it yet.  if the PG_BUSY page is
844  *	being paged out then it means that someone else has already started
845  *	cleaning the page for us (how nice!).  in this case, if we
846  *	have syncio specified, then after we make our pass through the
847  *	object we need to wait for the other PG_BUSY pages to clear
848  *	off (i.e. we need to do an iosync).   also note that once a
849  *	page is PG_BUSY it must stay in its object until it is un-busyed.
850  */
851 
852 int
853 genfs_putpages(void *v)
854 {
855 	struct vop_putpages_args /* {
856 		struct vnode *a_vp;
857 		voff_t a_offlo;
858 		voff_t a_offhi;
859 		int a_flags;
860 	} */ * const ap = v;
861 
862 	return genfs_do_putpages(ap->a_vp, ap->a_offlo, ap->a_offhi,
863 	    ap->a_flags, NULL);
864 }
865 
866 int
867 genfs_do_putpages(struct vnode *vp, off_t startoff, off_t endoff,
868     int origflags, struct vm_page **busypg)
869 {
870 	struct uvm_object * const uobj = &vp->v_uobj;
871 	krwlock_t * const slock = uobj->vmobjlock;
872 	off_t nextoff;
873 	int i, error, npages, nback;
874 	int freeflag;
875 	/*
876 	 * This array is larger than it should so that it's size is constant.
877 	 * The right size is MAXPAGES.
878 	 */
879 	struct vm_page *pgs[MAXPHYS / MIN_PAGE_SIZE];
880 #define MAXPAGES (MAXPHYS / PAGE_SIZE)
881 	struct vm_page *pg, *tpg;
882 	struct uvm_page_array a;
883 	bool wasclean, needs_clean;
884 	bool async = (origflags & PGO_SYNCIO) == 0;
885 	bool pagedaemon = curlwp == uvm.pagedaemon_lwp;
886 	struct mount *trans_mp;
887 	int flags;
888 	bool modified;		/* if we write out any pages */
889 	bool holds_wapbl;
890 	bool cleanall;		/* try to pull off from the syncer's list */
891 	bool onworklst;
892 	bool nodirty;
893 	const bool dirtyonly = (origflags & (PGO_DEACTIVATE|PGO_FREE)) == 0;
894 
895 	UVMHIST_FUNC("genfs_putpages"); UVMHIST_CALLED(ubchist);
896 
897 	KASSERT(origflags & (PGO_CLEANIT|PGO_FREE|PGO_DEACTIVATE));
898 	KASSERT((startoff & PAGE_MASK) == 0 && (endoff & PAGE_MASK) == 0);
899 	KASSERT(startoff < endoff || endoff == 0);
900 	KASSERT(rw_write_held(slock));
901 
902 	UVMHIST_LOG(ubchist, "vp %#jx pages %jd off 0x%jx len 0x%jx",
903 	    (uintptr_t)vp, uobj->uo_npages, startoff, endoff - startoff);
904 
905 #ifdef DIAGNOSTIC
906 	if ((origflags & PGO_JOURNALLOCKED) && vp->v_mount->mnt_wapbl)
907                 WAPBL_JLOCK_ASSERT(vp->v_mount);
908 #endif
909 
910 	trans_mp = NULL;
911 	holds_wapbl = false;
912 
913 retry:
914 	modified = false;
915 	flags = origflags;
916 
917 	/*
918 	 * shortcut if we have no pages to process.
919 	 */
920 
921 	nodirty = radix_tree_empty_tagged_tree_p(&uobj->uo_pages,
922             UVM_PAGE_DIRTY_TAG);
923 #ifdef DIAGNOSTIC
924 	mutex_enter(vp->v_interlock);
925 	KASSERT((vp->v_iflag & VI_ONWORKLST) != 0 || nodirty);
926 	mutex_exit(vp->v_interlock);
927 #endif
928 	if (uobj->uo_npages == 0 || (dirtyonly && nodirty)) {
929 		mutex_enter(vp->v_interlock);
930 		if (vp->v_iflag & VI_ONWORKLST) {
931 			if (LIST_FIRST(&vp->v_dirtyblkhd) == NULL)
932 				vn_syncer_remove_from_worklist(vp);
933 		}
934 		mutex_exit(vp->v_interlock);
935 		if (trans_mp) {
936 			if (holds_wapbl)
937 				WAPBL_END(trans_mp);
938 			fstrans_done(trans_mp);
939 		}
940 		rw_exit(slock);
941 		return (0);
942 	}
943 
944 	/*
945 	 * the vnode has pages, set up to process the request.
946 	 */
947 
948 	if (trans_mp == NULL && (flags & PGO_CLEANIT) != 0) {
949 		if (pagedaemon) {
950 			/* Pagedaemon must not sleep here. */
951 			trans_mp = vp->v_mount;
952 			error = fstrans_start_nowait(trans_mp);
953 			if (error) {
954 				rw_exit(slock);
955 				return error;
956 			}
957 		} else {
958 			/*
959 			 * Cannot use vdeadcheck() here as this operation
960 			 * usually gets used from VOP_RECLAIM().  Test for
961 			 * change of v_mount instead and retry on change.
962 			 */
963 			rw_exit(slock);
964 			trans_mp = vp->v_mount;
965 			fstrans_start(trans_mp);
966 			if (vp->v_mount != trans_mp) {
967 				fstrans_done(trans_mp);
968 				trans_mp = NULL;
969 			} else {
970 				holds_wapbl = (trans_mp->mnt_wapbl &&
971 				    (origflags & PGO_JOURNALLOCKED) == 0);
972 				if (holds_wapbl) {
973 					error = WAPBL_BEGIN(trans_mp);
974 					if (error) {
975 						fstrans_done(trans_mp);
976 						return error;
977 					}
978 				}
979 			}
980 			rw_enter(slock, RW_WRITER);
981 			goto retry;
982 		}
983 	}
984 
985 	error = 0;
986 	wasclean = radix_tree_empty_tagged_tree_p(&uobj->uo_pages,
987             UVM_PAGE_WRITEBACK_TAG);
988 	nextoff = startoff;
989 	if (endoff == 0 || flags & PGO_ALLPAGES) {
990 		endoff = trunc_page(LLONG_MAX);
991 	}
992 
993 	/*
994 	 * if this vnode is known not to have dirty pages,
995 	 * don't bother to clean it out.
996 	 */
997 
998 	if (nodirty) {
999 #if !defined(DEBUG)
1000 		if (dirtyonly) {
1001 			goto skip_scan;
1002 		}
1003 #endif /* !defined(DEBUG) */
1004 		flags &= ~PGO_CLEANIT;
1005 	}
1006 
1007 	/*
1008 	 * start the loop to scan pages.
1009 	 */
1010 
1011 	cleanall = true;
1012 	freeflag = pagedaemon ? PG_PAGEOUT : PG_RELEASED;
1013 	uvm_page_array_init(&a);
1014 	for (;;) {
1015 		bool pgprotected;
1016 
1017 		/*
1018 		 * if !dirtyonly, iterate over all resident pages in the range.
1019 		 *
1020 		 * if dirtyonly, only possibly dirty pages are interesting.
1021 		 * however, if we are asked to sync for integrity, we should
1022 		 * wait on pages being written back by other threads as well.
1023 		 */
1024 
1025 		pg = uvm_page_array_fill_and_peek(&a, uobj, nextoff, 0,
1026 		    dirtyonly ? (UVM_PAGE_ARRAY_FILL_DIRTY |
1027 		    (!async ? UVM_PAGE_ARRAY_FILL_WRITEBACK : 0)) : 0);
1028 		if (pg == NULL) {
1029 			break;
1030 		}
1031 
1032 		KASSERT(pg->uobject == uobj);
1033 		KASSERT((pg->flags & (PG_RELEASED|PG_PAGEOUT)) == 0 ||
1034 		    (pg->flags & (PG_BUSY)) != 0);
1035 		KASSERT(pg->offset >= startoff);
1036 		KASSERT(pg->offset >= nextoff);
1037 		KASSERT(!dirtyonly ||
1038 		    uvm_pagegetdirty(pg) != UVM_PAGE_STATUS_CLEAN ||
1039 		    radix_tree_get_tag(&uobj->uo_pages,
1040 			pg->offset >> PAGE_SHIFT, UVM_PAGE_WRITEBACK_TAG));
1041 
1042 		if (pg->offset >= endoff) {
1043 			break;
1044 		}
1045 
1046 		/*
1047 		 * a preempt point.
1048 		 */
1049 
1050 		if (preempt_needed()) {
1051 			nextoff = pg->offset; /* visit this page again */
1052 			rw_exit(slock);
1053 			preempt();
1054 			/*
1055 			 * as we dropped the object lock, our cached pages can
1056 			 * be stale.
1057 			 */
1058 			uvm_page_array_clear(&a);
1059 			rw_enter(slock, RW_WRITER);
1060 			continue;
1061 		}
1062 
1063 		/*
1064 		 * if the current page is busy, wait for it to become unbusy.
1065 		 */
1066 
1067 		if ((pg->flags & PG_BUSY) != 0) {
1068 			UVMHIST_LOG(ubchist, "busy %#jx", (uintptr_t)pg,
1069 			   0, 0, 0);
1070 			if ((pg->flags & (PG_RELEASED|PG_PAGEOUT)) != 0
1071 			    && (flags & PGO_BUSYFAIL) != 0) {
1072 				UVMHIST_LOG(ubchist, "busyfail %#jx",
1073 				    (uintptr_t)pg, 0, 0, 0);
1074 				error = EDEADLK;
1075 				if (busypg != NULL)
1076 					*busypg = pg;
1077 				break;
1078 			}
1079 			if (pagedaemon) {
1080 				/*
1081 				 * someone has taken the page while we
1082 				 * dropped the lock for fstrans_start.
1083 				 */
1084 				break;
1085 			}
1086 			/*
1087 			 * don't bother to wait on other's activities
1088 			 * unless we are asked to sync for integrity.
1089 			 */
1090 			if (!async && (flags & PGO_RECLAIM) == 0) {
1091 				wasclean = false;
1092 				nextoff = pg->offset + PAGE_SIZE;
1093 				uvm_page_array_advance(&a);
1094 				continue;
1095 			}
1096 			nextoff = pg->offset; /* visit this page again */
1097 			uvm_pagewait(pg, slock, "genput");
1098 			/*
1099 			 * as we dropped the object lock, our cached pages can
1100 			 * be stale.
1101 			 */
1102 			uvm_page_array_clear(&a);
1103 			rw_enter(slock, RW_WRITER);
1104 			continue;
1105 		}
1106 
1107 		nextoff = pg->offset + PAGE_SIZE;
1108 		uvm_page_array_advance(&a);
1109 
1110 		/*
1111 		 * if we're freeing, remove all mappings of the page now.
1112 		 * if we're cleaning, check if the page is needs to be cleaned.
1113 		 */
1114 
1115 		pgprotected = false;
1116 		if (flags & PGO_FREE) {
1117 			pmap_page_protect(pg, VM_PROT_NONE);
1118 			pgprotected = true;
1119 		} else if (flags & PGO_CLEANIT) {
1120 
1121 			/*
1122 			 * if we still have some hope to pull this vnode off
1123 			 * from the syncer queue, write-protect the page.
1124 			 */
1125 
1126 			if (cleanall && wasclean) {
1127 
1128 				/*
1129 				 * uobj pages get wired only by uvm_fault
1130 				 * where uobj is locked.
1131 				 */
1132 
1133 				if (pg->wire_count == 0) {
1134 					pmap_page_protect(pg,
1135 					    VM_PROT_READ|VM_PROT_EXECUTE);
1136 					pgprotected = true;
1137 				} else {
1138 					cleanall = false;
1139 				}
1140 			}
1141 		}
1142 
1143 		if (flags & PGO_CLEANIT) {
1144 			needs_clean = uvm_pagecheckdirty(pg, pgprotected);
1145 		} else {
1146 			needs_clean = false;
1147 		}
1148 
1149 		/*
1150 		 * if we're cleaning, build a cluster.
1151 		 * the cluster will consist of pages which are currently dirty.
1152 		 * if not cleaning, just operate on the one page.
1153 		 */
1154 
1155 		if (needs_clean) {
1156 			wasclean = false;
1157 			memset(pgs, 0, sizeof(pgs));
1158 			pg->flags |= PG_BUSY;
1159 			UVM_PAGE_OWN(pg, "genfs_putpages");
1160 
1161 			/*
1162 			 * let the fs constrain the offset range of the cluster.
1163 			 * we additionally constrain the range here such that
1164 			 * it fits in the "pgs" pages array.
1165 			 */
1166 
1167 			off_t fslo, fshi, genlo, lo, off = pg->offset;
1168 			GOP_PUTRANGE(vp, off, &fslo, &fshi);
1169 			KASSERT(fslo == trunc_page(fslo));
1170 			KASSERT(fslo <= off);
1171 			KASSERT(fshi == trunc_page(fshi));
1172 			KASSERT(fshi == 0 || off < fshi);
1173 
1174 			if (off > MAXPHYS / 2)
1175 				genlo = trunc_page(off - (MAXPHYS / 2));
1176 			else
1177 				genlo = 0;
1178 			lo = MAX(fslo, genlo);
1179 
1180 			/*
1181 			 * first look backward.
1182 			 */
1183 
1184 			npages = (off - lo) >> PAGE_SHIFT;
1185 			nback = npages;
1186 			uvn_findpages(uobj, off - PAGE_SIZE, &nback,
1187 			    &pgs[0], NULL,
1188 			    UFP_NOWAIT|UFP_NOALLOC|UFP_DIRTYONLY|UFP_BACKWARD);
1189 			if (nback) {
1190 				memmove(&pgs[0], &pgs[npages - nback],
1191 				    nback * sizeof(pgs[0]));
1192 				if (npages - nback < nback)
1193 					memset(&pgs[nback], 0,
1194 					    (npages - nback) * sizeof(pgs[0]));
1195 				else
1196 					memset(&pgs[npages - nback], 0,
1197 					    nback * sizeof(pgs[0]));
1198 			}
1199 
1200 			/*
1201 			 * then plug in our page of interest.
1202 			 */
1203 
1204 			pgs[nback] = pg;
1205 
1206 			/*
1207 			 * then look forward to fill in the remaining space in
1208 			 * the array of pages.
1209 			 *
1210 			 * pass our cached array of pages so that hopefully
1211 			 * uvn_findpages can find some good pages in it.
1212 			 * the array a was filled above with the one of
1213 			 * following sets of flags:
1214 			 *	0
1215 			 *	UVM_PAGE_ARRAY_FILL_DIRTY
1216 			 *	UVM_PAGE_ARRAY_FILL_DIRTY|WRITEBACK
1217 			 */
1218 
1219 			npages = MAXPAGES - nback - 1;
1220 			if (fshi)
1221 				npages = MIN(npages,
1222 					     (fshi - off - 1) >> PAGE_SHIFT);
1223 			uvn_findpages(uobj, off + PAGE_SIZE, &npages,
1224 			    &pgs[nback + 1], NULL,
1225 			    UFP_NOWAIT|UFP_NOALLOC|UFP_DIRTYONLY);
1226 			npages += nback + 1;
1227 		} else {
1228 			pgs[0] = pg;
1229 			npages = 1;
1230 			nback = 0;
1231 		}
1232 
1233 		/*
1234 		 * apply FREE or DEACTIVATE options if requested.
1235 		 */
1236 
1237 		for (i = 0; i < npages; i++) {
1238 			tpg = pgs[i];
1239 			KASSERT(tpg->uobject == uobj);
1240 			KASSERT(i == 0 ||
1241 			    pgs[i-1]->offset + PAGE_SIZE == tpg->offset);
1242 			KASSERT(!needs_clean || uvm_pagegetdirty(pgs[i]) !=
1243 			    UVM_PAGE_STATUS_DIRTY);
1244 			if (needs_clean) {
1245 				/*
1246 				 * mark pages as WRITEBACK so that concurrent
1247 				 * fsync can find and wait for our activities.
1248 				 */
1249 				radix_tree_set_tag(&uobj->uo_pages,
1250 				    pgs[i]->offset >> PAGE_SHIFT,
1251 				    UVM_PAGE_WRITEBACK_TAG);
1252 			}
1253 			if (tpg->offset < startoff || tpg->offset >= endoff)
1254 				continue;
1255 			if (flags & PGO_DEACTIVATE && tpg->wire_count == 0) {
1256 				uvm_pagelock(tpg);
1257 				uvm_pagedeactivate(tpg);
1258 				uvm_pageunlock(tpg);
1259 			} else if (flags & PGO_FREE) {
1260 				pmap_page_protect(tpg, VM_PROT_NONE);
1261 				if (tpg->flags & PG_BUSY) {
1262 					tpg->flags |= freeflag;
1263 					if (pagedaemon) {
1264 						uvm_pageout_start(1);
1265 						uvm_pagelock(tpg);
1266 						uvm_pagedequeue(tpg);
1267 						uvm_pageunlock(tpg);
1268 					}
1269 				} else {
1270 
1271 					/*
1272 					 * ``page is not busy''
1273 					 * implies that npages is 1
1274 					 * and needs_clean is false.
1275 					 */
1276 
1277 					KASSERT(npages == 1);
1278 					KASSERT(!needs_clean);
1279 					KASSERT(pg == tpg);
1280 					KASSERT(nextoff ==
1281 					    tpg->offset + PAGE_SIZE);
1282 					uvm_pagefree(tpg);
1283 					if (pagedaemon)
1284 						uvmexp.pdfreed++;
1285 				}
1286 			}
1287 		}
1288 		if (needs_clean) {
1289 			modified = true;
1290 			KASSERT(nextoff == pg->offset + PAGE_SIZE);
1291 			KASSERT(nback < npages);
1292 			nextoff = pg->offset + ((npages - nback) << PAGE_SHIFT);
1293 			KASSERT(pgs[nback] == pg);
1294 			KASSERT(nextoff == pgs[npages - 1]->offset + PAGE_SIZE);
1295 
1296 			/*
1297 			 * start the i/o.
1298 			 */
1299 			rw_exit(slock);
1300 			error = GOP_WRITE(vp, pgs, npages, flags);
1301 			/*
1302 			 * as we dropped the object lock, our cached pages can
1303 			 * be stale.
1304 			 */
1305 			uvm_page_array_clear(&a);
1306 			rw_enter(slock, RW_WRITER);
1307 			if (error) {
1308 				break;
1309 			}
1310 		}
1311 	}
1312 	uvm_page_array_fini(&a);
1313 
1314 	/*
1315 	 * update ctime/mtime if the modification we started writing out might
1316 	 * be from mmap'ed write.
1317 	 *
1318 	 * this is necessary when an application keeps a file mmaped and
1319 	 * repeatedly modifies it via the window.  note that, because we
1320 	 * don't always write-protect pages when cleaning, such modifications
1321 	 * might not involve any page faults.
1322 	 */
1323 
1324 	mutex_enter(vp->v_interlock);
1325 	if (modified && (vp->v_iflag & VI_WRMAP) != 0 &&
1326 	    (vp->v_type != VBLK ||
1327 	    (vp->v_mount->mnt_flag & MNT_NODEVMTIME) == 0)) {
1328 		GOP_MARKUPDATE(vp, GOP_UPDATE_MODIFIED);
1329 	}
1330 
1331 	/*
1332 	 * if we no longer have any possibly dirty pages, take us off the
1333 	 * syncer list.
1334 	 */
1335 
1336 	if ((vp->v_iflag & VI_ONWORKLST) != 0 &&
1337 	    radix_tree_empty_tagged_tree_p(&uobj->uo_pages,
1338 	    UVM_PAGE_DIRTY_TAG)) {
1339 		if (LIST_FIRST(&vp->v_dirtyblkhd) == NULL)
1340 			vn_syncer_remove_from_worklist(vp);
1341 	}
1342 
1343 #if !defined(DEBUG)
1344 skip_scan:
1345 #endif /* !defined(DEBUG) */
1346 
1347 	/* Wait for output to complete. */
1348 	rw_exit(slock);
1349 	if (!wasclean && !async && vp->v_numoutput != 0) {
1350 		while (vp->v_numoutput != 0)
1351 			cv_wait(&vp->v_cv, vp->v_interlock);
1352 	}
1353 	onworklst = (vp->v_iflag & VI_ONWORKLST) != 0;
1354 	mutex_exit(vp->v_interlock);
1355 
1356 	if ((flags & PGO_RECLAIM) != 0 && onworklst) {
1357 		/*
1358 		 * in the case of PGO_RECLAIM, ensure to make the vnode clean.
1359 		 * retrying is not a big deal because, in many cases,
1360 		 * uobj->uo_npages is already 0 here.
1361 		 */
1362 		rw_enter(slock, RW_WRITER);
1363 		goto retry;
1364 	}
1365 
1366 	if (trans_mp) {
1367 		if (holds_wapbl)
1368 			WAPBL_END(trans_mp);
1369 		fstrans_done(trans_mp);
1370 	}
1371 
1372 	return (error);
1373 }
1374 
1375 /*
1376  * Default putrange method for file systems that do not care
1377  * how many pages are given to one GOP_WRITE() call.
1378  */
1379 void
1380 genfs_gop_putrange(struct vnode *vp, off_t off, off_t *lop, off_t *hip)
1381 {
1382 
1383 	*lop = 0;
1384 	*hip = 0;
1385 }
1386 
1387 int
1388 genfs_gop_write(struct vnode *vp, struct vm_page **pgs, int npages, int flags)
1389 {
1390 	off_t off;
1391 	vaddr_t kva;
1392 	size_t len;
1393 	int error;
1394 	UVMHIST_FUNC(__func__); UVMHIST_CALLED(ubchist);
1395 
1396 	UVMHIST_LOG(ubchist, "vp %#jx pgs %#jx npages %jd flags 0x%jx",
1397 	    (uintptr_t)vp, (uintptr_t)pgs, npages, flags);
1398 
1399 	off = pgs[0]->offset;
1400 	kva = uvm_pagermapin(pgs, npages,
1401 	    UVMPAGER_MAPIN_WRITE | UVMPAGER_MAPIN_WAITOK);
1402 	len = npages << PAGE_SHIFT;
1403 
1404 	error = genfs_do_io(vp, off, kva, len, flags, UIO_WRITE,
1405 			    uvm_aio_aiodone);
1406 
1407 	return error;
1408 }
1409 
1410 /*
1411  * genfs_gop_write_rwmap:
1412  *
1413  * a variant of genfs_gop_write.  it's used by UDF for its directory buffers.
1414  * this maps pages with PROT_WRITE so that VOP_STRATEGY can modifies
1415  * the contents before writing it out to the underlying storage.
1416  */
1417 
1418 int
1419 genfs_gop_write_rwmap(struct vnode *vp, struct vm_page **pgs, int npages,
1420     int flags)
1421 {
1422 	off_t off;
1423 	vaddr_t kva;
1424 	size_t len;
1425 	int error;
1426 	UVMHIST_FUNC(__func__); UVMHIST_CALLED(ubchist);
1427 
1428 	UVMHIST_LOG(ubchist, "vp %#jx pgs %#jx npages %jd flags 0x%jx",
1429 	    (uintptr_t)vp, (uintptr_t)pgs, npages, flags);
1430 
1431 	off = pgs[0]->offset;
1432 	kva = uvm_pagermapin(pgs, npages,
1433 	    UVMPAGER_MAPIN_READ | UVMPAGER_MAPIN_WAITOK);
1434 	len = npages << PAGE_SHIFT;
1435 
1436 	error = genfs_do_io(vp, off, kva, len, flags, UIO_WRITE,
1437 			    uvm_aio_aiodone);
1438 
1439 	return error;
1440 }
1441 
1442 /*
1443  * Backend routine for doing I/O to vnode pages.  Pages are already locked
1444  * and mapped into kernel memory.  Here we just look up the underlying
1445  * device block addresses and call the strategy routine.
1446  */
1447 
1448 static int
1449 genfs_do_io(struct vnode *vp, off_t off, vaddr_t kva, size_t len, int flags,
1450     enum uio_rw rw, void (*iodone)(struct buf *))
1451 {
1452 	int s, error;
1453 	int fs_bshift, dev_bshift;
1454 	off_t eof, offset, startoffset;
1455 	size_t bytes, iobytes, skipbytes;
1456 	struct buf *mbp, *bp;
1457 	const bool async = (flags & PGO_SYNCIO) == 0;
1458 	const bool lazy = (flags & PGO_LAZY) == 0;
1459 	const bool iowrite = rw == UIO_WRITE;
1460 	const int brw = iowrite ? B_WRITE : B_READ;
1461 	UVMHIST_FUNC(__func__); UVMHIST_CALLED(ubchist);
1462 
1463 	UVMHIST_LOG(ubchist, "vp %#jx kva %#jx len 0x%jx flags 0x%jx",
1464 	    (uintptr_t)vp, (uintptr_t)kva, len, flags);
1465 
1466 	KASSERT(vp->v_size <= vp->v_writesize);
1467 	GOP_SIZE(vp, vp->v_writesize, &eof, 0);
1468 	if (vp->v_type != VBLK) {
1469 		fs_bshift = vp->v_mount->mnt_fs_bshift;
1470 		dev_bshift = vp->v_mount->mnt_dev_bshift;
1471 	} else {
1472 		fs_bshift = DEV_BSHIFT;
1473 		dev_bshift = DEV_BSHIFT;
1474 	}
1475 	error = 0;
1476 	startoffset = off;
1477 	bytes = MIN(len, eof - startoffset);
1478 	skipbytes = 0;
1479 	KASSERT(bytes != 0);
1480 
1481 	if (iowrite) {
1482 		/*
1483 		 * why += 2?
1484 		 * 1 for biodone, 1 for uvm_aio_aiodone.
1485 		 */
1486 		mutex_enter(vp->v_interlock);
1487 		vp->v_numoutput += 2;
1488 		mutex_exit(vp->v_interlock);
1489 	}
1490 	mbp = getiobuf(vp, true);
1491 	UVMHIST_LOG(ubchist, "vp %#jx mbp %#jx num now %jd bytes 0x%jx",
1492 	    (uintptr_t)vp, (uintptr_t)mbp, vp->v_numoutput, bytes);
1493 	mbp->b_bufsize = len;
1494 	mbp->b_data = (void *)kva;
1495 	mbp->b_resid = mbp->b_bcount = bytes;
1496 	mbp->b_cflags |= BC_BUSY | BC_AGE;
1497 	if (async) {
1498 		mbp->b_flags = brw | B_ASYNC;
1499 		mbp->b_iodone = iodone;
1500 	} else {
1501 		mbp->b_flags = brw;
1502 		mbp->b_iodone = NULL;
1503 	}
1504 	if (curlwp == uvm.pagedaemon_lwp)
1505 		BIO_SETPRIO(mbp, BPRIO_TIMELIMITED);
1506 	else if (async || lazy)
1507 		BIO_SETPRIO(mbp, BPRIO_TIMENONCRITICAL);
1508 	else
1509 		BIO_SETPRIO(mbp, BPRIO_TIMECRITICAL);
1510 
1511 	bp = NULL;
1512 	for (offset = startoffset;
1513 	    bytes > 0;
1514 	    offset += iobytes, bytes -= iobytes) {
1515 		int run;
1516 		daddr_t lbn, blkno;
1517 		struct vnode *devvp;
1518 
1519 		/*
1520 		 * bmap the file to find out the blkno to read from and
1521 		 * how much we can read in one i/o.  if bmap returns an error,
1522 		 * skip the rest of the top-level i/o.
1523 		 */
1524 
1525 		lbn = offset >> fs_bshift;
1526 		error = VOP_BMAP(vp, lbn, &devvp, &blkno, &run);
1527 		if (error) {
1528 			UVMHIST_LOG(ubchist, "VOP_BMAP lbn 0x%jx -> %jd\n",
1529 			    lbn, error, 0, 0);
1530 			skipbytes += bytes;
1531 			bytes = 0;
1532 			goto loopdone;
1533 		}
1534 
1535 		/*
1536 		 * see how many pages can be read with this i/o.
1537 		 * reduce the i/o size if necessary to avoid
1538 		 * overwriting pages with valid data.
1539 		 */
1540 
1541 		iobytes = MIN((((off_t)lbn + 1 + run) << fs_bshift) - offset,
1542 		    bytes);
1543 
1544 		/*
1545 		 * if this block isn't allocated, zero it instead of
1546 		 * reading it.  unless we are going to allocate blocks,
1547 		 * mark the pages we zeroed PG_RDONLY.
1548 		 */
1549 
1550 		if (blkno == (daddr_t)-1) {
1551 			if (!iowrite) {
1552 				memset((char *)kva + (offset - startoffset), 0,
1553 				    iobytes);
1554 			}
1555 			skipbytes += iobytes;
1556 			continue;
1557 		}
1558 
1559 		/*
1560 		 * allocate a sub-buf for this piece of the i/o
1561 		 * (or just use mbp if there's only 1 piece),
1562 		 * and start it going.
1563 		 */
1564 
1565 		if (offset == startoffset && iobytes == bytes) {
1566 			bp = mbp;
1567 		} else {
1568 			UVMHIST_LOG(ubchist, "vp %#jx bp %#jx num now %jd",
1569 			    (uintptr_t)vp, (uintptr_t)bp, vp->v_numoutput, 0);
1570 			bp = getiobuf(vp, true);
1571 			nestiobuf_setup(mbp, bp, offset - startoffset, iobytes);
1572 		}
1573 		bp->b_lblkno = 0;
1574 
1575 		/* adjust physical blkno for partial blocks */
1576 		bp->b_blkno = blkno + ((offset - ((off_t)lbn << fs_bshift)) >>
1577 		    dev_bshift);
1578 
1579 		UVMHIST_LOG(ubchist,
1580 		    "bp %#jx offset 0x%jx bcount 0x%jx blkno 0x%jx",
1581 		    (uintptr_t)bp, offset, bp->b_bcount, bp->b_blkno);
1582 
1583 		VOP_STRATEGY(devvp, bp);
1584 	}
1585 
1586 loopdone:
1587 	if (skipbytes) {
1588 		UVMHIST_LOG(ubchist, "skipbytes %jd", skipbytes, 0,0,0);
1589 	}
1590 	nestiobuf_done(mbp, skipbytes, error);
1591 	if (async) {
1592 		UVMHIST_LOG(ubchist, "returning 0 (async)", 0,0,0,0);
1593 		return (0);
1594 	}
1595 	UVMHIST_LOG(ubchist, "waiting for mbp %#jx", (uintptr_t)mbp, 0, 0, 0);
1596 	error = biowait(mbp);
1597 	s = splbio();
1598 	(*iodone)(mbp);
1599 	splx(s);
1600 	UVMHIST_LOG(ubchist, "returning, error %jd", error, 0, 0, 0);
1601 	return (error);
1602 }
1603 
1604 int
1605 genfs_compat_getpages(void *v)
1606 {
1607 	struct vop_getpages_args /* {
1608 		struct vnode *a_vp;
1609 		voff_t a_offset;
1610 		struct vm_page **a_m;
1611 		int *a_count;
1612 		int a_centeridx;
1613 		vm_prot_t a_access_type;
1614 		int a_advice;
1615 		int a_flags;
1616 	} */ *ap = v;
1617 
1618 	off_t origoffset;
1619 	struct vnode *vp = ap->a_vp;
1620 	struct uvm_object *uobj = &vp->v_uobj;
1621 	struct vm_page *pg, **pgs;
1622 	vaddr_t kva;
1623 	int i, error, orignpages, npages;
1624 	struct iovec iov;
1625 	struct uio uio;
1626 	kauth_cred_t cred = curlwp->l_cred;
1627 	const bool memwrite = (ap->a_access_type & VM_PROT_WRITE) != 0;
1628 
1629 	error = 0;
1630 	origoffset = ap->a_offset;
1631 	orignpages = *ap->a_count;
1632 	pgs = ap->a_m;
1633 
1634 	if (ap->a_flags & PGO_LOCKED) {
1635 		uvn_findpages(uobj, origoffset, ap->a_count, ap->a_m, NULL,
1636 		    UFP_NOWAIT|UFP_NOALLOC| (memwrite ? UFP_NORDONLY : 0));
1637 
1638 		error = ap->a_m[ap->a_centeridx] == NULL ? EBUSY : 0;
1639 		return error;
1640 	}
1641 	if (origoffset + (ap->a_centeridx << PAGE_SHIFT) >= vp->v_size) {
1642 		rw_exit(uobj->vmobjlock);
1643 		return EINVAL;
1644 	}
1645 	if ((ap->a_flags & PGO_SYNCIO) == 0) {
1646 		rw_exit(uobj->vmobjlock);
1647 		return 0;
1648 	}
1649 	npages = orignpages;
1650 	uvn_findpages(uobj, origoffset, &npages, pgs, NULL, UFP_ALL);
1651 	rw_exit(uobj->vmobjlock);
1652 	kva = uvm_pagermapin(pgs, npages,
1653 	    UVMPAGER_MAPIN_READ | UVMPAGER_MAPIN_WAITOK);
1654 	for (i = 0; i < npages; i++) {
1655 		pg = pgs[i];
1656 		if ((pg->flags & PG_FAKE) == 0) {
1657 			continue;
1658 		}
1659 		iov.iov_base = (char *)kva + (i << PAGE_SHIFT);
1660 		iov.iov_len = PAGE_SIZE;
1661 		uio.uio_iov = &iov;
1662 		uio.uio_iovcnt = 1;
1663 		uio.uio_offset = origoffset + (i << PAGE_SHIFT);
1664 		uio.uio_rw = UIO_READ;
1665 		uio.uio_resid = PAGE_SIZE;
1666 		UIO_SETUP_SYSSPACE(&uio);
1667 		/* XXX vn_lock */
1668 		error = VOP_READ(vp, &uio, 0, cred);
1669 		if (error) {
1670 			break;
1671 		}
1672 		if (uio.uio_resid) {
1673 			memset(iov.iov_base, 0, uio.uio_resid);
1674 		}
1675 	}
1676 	uvm_pagermapout(kva, npages);
1677 	rw_enter(uobj->vmobjlock, RW_WRITER);
1678 	for (i = 0; i < npages; i++) {
1679 		pg = pgs[i];
1680 		if (error && (pg->flags & PG_FAKE) != 0) {
1681 			pg->flags |= PG_RELEASED;
1682 		} else {
1683 			uvm_pagemarkdirty(pg, UVM_PAGE_STATUS_UNKNOWN);
1684 			uvm_pagelock(pg);
1685 			uvm_pageactivate(pg);
1686 			uvm_pageunlock(pg);
1687 		}
1688 	}
1689 	if (error) {
1690 		uvm_page_unbusy(pgs, npages);
1691 	}
1692 	rw_exit(uobj->vmobjlock);
1693 	return error;
1694 }
1695 
1696 int
1697 genfs_compat_gop_write(struct vnode *vp, struct vm_page **pgs, int npages,
1698     int flags)
1699 {
1700 	off_t offset;
1701 	struct iovec iov;
1702 	struct uio uio;
1703 	kauth_cred_t cred = curlwp->l_cred;
1704 	struct buf *bp;
1705 	vaddr_t kva;
1706 	int error;
1707 
1708 	offset = pgs[0]->offset;
1709 	kva = uvm_pagermapin(pgs, npages,
1710 	    UVMPAGER_MAPIN_WRITE | UVMPAGER_MAPIN_WAITOK);
1711 
1712 	iov.iov_base = (void *)kva;
1713 	iov.iov_len = npages << PAGE_SHIFT;
1714 	uio.uio_iov = &iov;
1715 	uio.uio_iovcnt = 1;
1716 	uio.uio_offset = offset;
1717 	uio.uio_rw = UIO_WRITE;
1718 	uio.uio_resid = npages << PAGE_SHIFT;
1719 	UIO_SETUP_SYSSPACE(&uio);
1720 	/* XXX vn_lock */
1721 	error = VOP_WRITE(vp, &uio, 0, cred);
1722 
1723 	mutex_enter(vp->v_interlock);
1724 	vp->v_numoutput++;
1725 	mutex_exit(vp->v_interlock);
1726 
1727 	bp = getiobuf(vp, true);
1728 	bp->b_cflags |= BC_BUSY | BC_AGE;
1729 	bp->b_lblkno = offset >> vp->v_mount->mnt_fs_bshift;
1730 	bp->b_data = (char *)kva;
1731 	bp->b_bcount = npages << PAGE_SHIFT;
1732 	bp->b_bufsize = npages << PAGE_SHIFT;
1733 	bp->b_resid = 0;
1734 	bp->b_error = error;
1735 	uvm_aio_aiodone(bp);
1736 	return (error);
1737 }
1738 
1739 /*
1740  * Process a uio using direct I/O.  If we reach a part of the request
1741  * which cannot be processed in this fashion for some reason, just return.
1742  * The caller must handle some additional part of the request using
1743  * buffered I/O before trying direct I/O again.
1744  */
1745 
1746 void
1747 genfs_directio(struct vnode *vp, struct uio *uio, int ioflag)
1748 {
1749 	struct vmspace *vs;
1750 	struct iovec *iov;
1751 	vaddr_t va;
1752 	size_t len;
1753 	const int mask = DEV_BSIZE - 1;
1754 	int error;
1755 	bool need_wapbl = (vp->v_mount && vp->v_mount->mnt_wapbl &&
1756 	    (ioflag & IO_JOURNALLOCKED) == 0);
1757 
1758 #ifdef DIAGNOSTIC
1759 	if ((ioflag & IO_JOURNALLOCKED) && vp->v_mount->mnt_wapbl)
1760                 WAPBL_JLOCK_ASSERT(vp->v_mount);
1761 #endif
1762 
1763 	/*
1764 	 * We only support direct I/O to user space for now.
1765 	 */
1766 
1767 	if (VMSPACE_IS_KERNEL_P(uio->uio_vmspace)) {
1768 		return;
1769 	}
1770 
1771 	/*
1772 	 * If the vnode is mapped, we would need to get the getpages lock
1773 	 * to stabilize the bmap, but then we would get into trouble while
1774 	 * locking the pages if the pages belong to this same vnode (or a
1775 	 * multi-vnode cascade to the same effect).  Just fall back to
1776 	 * buffered I/O if the vnode is mapped to avoid this mess.
1777 	 */
1778 
1779 	if (vp->v_vflag & VV_MAPPED) {
1780 		return;
1781 	}
1782 
1783 	if (need_wapbl) {
1784 		error = WAPBL_BEGIN(vp->v_mount);
1785 		if (error)
1786 			return;
1787 	}
1788 
1789 	/*
1790 	 * Do as much of the uio as possible with direct I/O.
1791 	 */
1792 
1793 	vs = uio->uio_vmspace;
1794 	while (uio->uio_resid) {
1795 		iov = uio->uio_iov;
1796 		if (iov->iov_len == 0) {
1797 			uio->uio_iov++;
1798 			uio->uio_iovcnt--;
1799 			continue;
1800 		}
1801 		va = (vaddr_t)iov->iov_base;
1802 		len = MIN(iov->iov_len, genfs_maxdio);
1803 		len &= ~mask;
1804 
1805 		/*
1806 		 * If the next chunk is smaller than DEV_BSIZE or extends past
1807 		 * the current EOF, then fall back to buffered I/O.
1808 		 */
1809 
1810 		if (len == 0 || uio->uio_offset + len > vp->v_size) {
1811 			break;
1812 		}
1813 
1814 		/*
1815 		 * Check alignment.  The file offset must be at least
1816 		 * sector-aligned.  The exact constraint on memory alignment
1817 		 * is very hardware-dependent, but requiring sector-aligned
1818 		 * addresses there too is safe.
1819 		 */
1820 
1821 		if (uio->uio_offset & mask || va & mask) {
1822 			break;
1823 		}
1824 		error = genfs_do_directio(vs, va, len, vp, uio->uio_offset,
1825 					  uio->uio_rw);
1826 		if (error) {
1827 			break;
1828 		}
1829 		iov->iov_base = (char *)iov->iov_base + len;
1830 		iov->iov_len -= len;
1831 		uio->uio_offset += len;
1832 		uio->uio_resid -= len;
1833 	}
1834 
1835 	if (need_wapbl)
1836 		WAPBL_END(vp->v_mount);
1837 }
1838 
1839 /*
1840  * Iodone routine for direct I/O.  We don't do much here since the request is
1841  * always synchronous, so the caller will do most of the work after biowait().
1842  */
1843 
1844 static void
1845 genfs_dio_iodone(struct buf *bp)
1846 {
1847 
1848 	KASSERT((bp->b_flags & B_ASYNC) == 0);
1849 	if ((bp->b_flags & B_READ) == 0 && (bp->b_cflags & BC_AGE) != 0) {
1850 		mutex_enter(bp->b_objlock);
1851 		vwakeup(bp);
1852 		mutex_exit(bp->b_objlock);
1853 	}
1854 	putiobuf(bp);
1855 }
1856 
1857 /*
1858  * Process one chunk of a direct I/O request.
1859  */
1860 
1861 static int
1862 genfs_do_directio(struct vmspace *vs, vaddr_t uva, size_t len, struct vnode *vp,
1863     off_t off, enum uio_rw rw)
1864 {
1865 	struct vm_map *map;
1866 	struct pmap *upm, *kpm __unused;
1867 	size_t klen = round_page(uva + len) - trunc_page(uva);
1868 	off_t spoff, epoff;
1869 	vaddr_t kva, puva;
1870 	paddr_t pa;
1871 	vm_prot_t prot;
1872 	int error, rv __diagused, poff, koff;
1873 	const int pgoflags = PGO_CLEANIT | PGO_SYNCIO | PGO_JOURNALLOCKED |
1874 		(rw == UIO_WRITE ? PGO_FREE : 0);
1875 
1876 	/*
1877 	 * For writes, verify that this range of the file already has fully
1878 	 * allocated backing store.  If there are any holes, just punt and
1879 	 * make the caller take the buffered write path.
1880 	 */
1881 
1882 	if (rw == UIO_WRITE) {
1883 		daddr_t lbn, elbn, blkno;
1884 		int bsize, bshift, run;
1885 
1886 		bshift = vp->v_mount->mnt_fs_bshift;
1887 		bsize = 1 << bshift;
1888 		lbn = off >> bshift;
1889 		elbn = (off + len + bsize - 1) >> bshift;
1890 		while (lbn < elbn) {
1891 			error = VOP_BMAP(vp, lbn, NULL, &blkno, &run);
1892 			if (error) {
1893 				return error;
1894 			}
1895 			if (blkno == (daddr_t)-1) {
1896 				return ENOSPC;
1897 			}
1898 			lbn += 1 + run;
1899 		}
1900 	}
1901 
1902 	/*
1903 	 * Flush any cached pages for parts of the file that we're about to
1904 	 * access.  If we're writing, invalidate pages as well.
1905 	 */
1906 
1907 	spoff = trunc_page(off);
1908 	epoff = round_page(off + len);
1909 	rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
1910 	error = VOP_PUTPAGES(vp, spoff, epoff, pgoflags);
1911 	if (error) {
1912 		return error;
1913 	}
1914 
1915 	/*
1916 	 * Wire the user pages and remap them into kernel memory.
1917 	 */
1918 
1919 	prot = rw == UIO_READ ? VM_PROT_READ | VM_PROT_WRITE : VM_PROT_READ;
1920 	error = uvm_vslock(vs, (void *)uva, len, prot);
1921 	if (error) {
1922 		return error;
1923 	}
1924 
1925 	map = &vs->vm_map;
1926 	upm = vm_map_pmap(map);
1927 	kpm = vm_map_pmap(kernel_map);
1928 	puva = trunc_page(uva);
1929 	kva = uvm_km_alloc(kernel_map, klen, atop(puva) & uvmexp.colormask,
1930 	    UVM_KMF_VAONLY | UVM_KMF_WAITVA | UVM_KMF_COLORMATCH);
1931 	for (poff = 0; poff < klen; poff += PAGE_SIZE) {
1932 		rv = pmap_extract(upm, puva + poff, &pa);
1933 		KASSERT(rv);
1934 		pmap_kenter_pa(kva + poff, pa, prot, PMAP_WIRED);
1935 	}
1936 	pmap_update(kpm);
1937 
1938 	/*
1939 	 * Do the I/O.
1940 	 */
1941 
1942 	koff = uva - trunc_page(uva);
1943 	error = genfs_do_io(vp, off, kva + koff, len, PGO_SYNCIO, rw,
1944 			    genfs_dio_iodone);
1945 
1946 	/*
1947 	 * Tear down the kernel mapping.
1948 	 */
1949 
1950 	pmap_kremove(kva, klen);
1951 	pmap_update(kpm);
1952 	uvm_km_free(kernel_map, kva, klen, UVM_KMF_VAONLY);
1953 
1954 	/*
1955 	 * Unwire the user pages.
1956 	 */
1957 
1958 	uvm_vsunlock(vs, (void *)uva, len);
1959 	return error;
1960 }
1961