Use SYSREF to reference count struct vnode. v_usecount is now
[dragonfly.git] / sys / kern / vfs_bio.c
CommitLineData
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1/*
2 * Copyright (c) 1994,1997 John S. Dyson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice immediately at the beginning of the file, without modification,
10 * this list of conditions, and the following disclaimer.
11 * 2. Absolutely no warranty of function or purpose is made by the author
12 * John S. Dyson.
13 *
14 * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.242.2.20 2003/05/28 18:38:10 alc Exp $
3c37c940 15 * $DragonFly: src/sys/kern/vfs_bio.c,v 1.90 2007/05/06 19:23:31 dillon Exp $
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16 */
17
18/*
19 * this file contains a new buffer I/O scheme implementing a coherent
20 * VM object and buffer cache scheme. Pains have been taken to make
21 * sure that the performance degradation associated with schemes such
22 * as this is not realized.
23 *
24 * Author: John S. Dyson
25 * Significant help during the development and debugging phases
26 * had been provided by David Greenman, also of the FreeBSD core team.
27 *
28 * see man buf(9) for more info.
29 */
30
31#include <sys/param.h>
32#include <sys/systm.h>
33#include <sys/buf.h>
34#include <sys/conf.h>
35#include <sys/eventhandler.h>
36#include <sys/lock.h>
37#include <sys/malloc.h>
38#include <sys/mount.h>
39#include <sys/kernel.h>
40#include <sys/kthread.h>
41#include <sys/proc.h>
42#include <sys/reboot.h>
43#include <sys/resourcevar.h>
44#include <sys/sysctl.h>
45#include <sys/vmmeter.h>
46#include <sys/vnode.h>
3020e3be 47#include <sys/proc.h>
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48#include <vm/vm.h>
49#include <vm/vm_param.h>
50#include <vm/vm_kern.h>
51#include <vm/vm_pageout.h>
52#include <vm/vm_page.h>
53#include <vm/vm_object.h>
54#include <vm/vm_extern.h>
55#include <vm/vm_map.h>
654a39f0 56
3020e3be 57#include <sys/buf2.h>
654a39f0 58#include <sys/thread2.h>
f832287e 59#include <sys/spinlock2.h>
12e4aaff 60#include <vm/vm_page2.h>
984263bc 61
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62#include "opt_ddb.h"
63#ifdef DDB
64#include <ddb/ddb.h>
65#endif
66
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67/*
68 * Buffer queues.
69 */
70#define BUFFER_QUEUES 6
71enum bufq_type {
72 BQUEUE_NONE, /* not on any queue */
73 BQUEUE_LOCKED, /* locked buffers */
74 BQUEUE_CLEAN, /* non-B_DELWRI buffers */
75 BQUEUE_DIRTY, /* B_DELWRI buffers */
76 BQUEUE_EMPTYKVA, /* empty buffer headers with KVA assignment */
77 BQUEUE_EMPTY /* empty buffer headers */
78};
79TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES];
80
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81static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
82
83struct bio_ops bioops; /* I/O operation notification */
84
85struct buf *buf; /* buffer header pool */
984263bc 86
c8e4131d 87static void vm_hold_free_pages(struct buf *bp, vm_offset_t from,
984263bc 88 vm_offset_t to);
c8e4131d 89static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
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90 vm_offset_t to);
91static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
92 int pageno, vm_page_t m);
c8e4131d 93static void vfs_clean_pages(struct buf *bp);
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94static void vfs_setdirty(struct buf *bp);
95static void vfs_vmio_release(struct buf *bp);
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96static int flushbufqueues(void);
97
402ed7e1 98static void buf_daemon (void);
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99/*
100 * bogus page -- for I/O to/from partially complete buffers
101 * this is a temporary solution to the problem, but it is not
102 * really that bad. it would be better to split the buffer
103 * for input in the case of buffers partially already in memory,
104 * but the code is intricate enough already.
105 */
106vm_page_t bogus_page;
984263bc 107int runningbufspace;
a0c36a34 108
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109/*
110 * These are all static, but make the ones we export globals so we do
111 * not need to use compiler magic.
112 */
113int bufspace, maxbufspace,
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114 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace;
115static int bufreusecnt, bufdefragcnt, buffreekvacnt;
984263bc 116static int lorunningspace, hirunningspace, runningbufreq;
460426e6 117int numdirtybuffers, lodirtybuffers, hidirtybuffers;
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118static int numfreebuffers, lofreebuffers, hifreebuffers;
119static int getnewbufcalls;
120static int getnewbufrestarts;
121
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122static int needsbuffer; /* locked by needsbuffer_spin */
123static int bd_request; /* locked by needsbuffer_spin */
124static struct spinlock needsbuffer_spin;
125
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126/*
127 * Sysctls for operational control of the buffer cache.
128 */
129SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
130 "Number of dirty buffers to flush before bufdaemon becomes inactive");
131SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
bb606263 132 "High watermark used to trigger explicit flushing of dirty buffers");
3f779080 133SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
bb606263 134 "Low watermark for special reserve in low-memory situations");
3f779080 135SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
bb606263 136 "High watermark for special reserve in low-memory situations");
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137SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
138 "Minimum amount of buffer space required for active I/O");
139SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
140 "Maximum amount of buffer space to usable for active I/O");
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141/*
142 * Sysctls determining current state of the buffer cache.
143 */
144SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
145 "Pending number of dirty buffers");
146SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
147 "Number of free buffers on the buffer cache free list");
148SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
bb606263 149 "I/O bytes currently in progress due to asynchronous writes");
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150SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
151 "Hard limit on maximum amount of memory usable for buffer space");
152SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
153 "Soft limit on maximum amount of memory usable for buffer space");
154SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
155 "Minimum amount of memory to reserve for system buffer space");
156SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
157 "Amount of memory available for buffers");
158SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace,
bb606263 159 0, "Maximum amount of memory reserved for buffers using malloc");
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160SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
161 "Amount of memory left for buffers using malloc-scheme");
162SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0,
163 "New buffer header acquisition requests");
164SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, &getnewbufrestarts,
165 0, "New buffer header acquisition restarts");
166SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RD, &bufdefragcnt, 0,
bb606263 167 "Buffer acquisition restarts due to fragmented buffer map");
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168SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RD, &buffreekvacnt, 0,
169 "Amount of time KVA space was deallocated in an arbitrary buffer");
170SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RD, &bufreusecnt, 0,
171 "Amount of time buffer re-use operations were successful");
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172SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf),
173 "sizeof(struct buf)");
984263bc 174
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175char *buf_wmesg = BUF_WMESG;
176
177extern int vm_swap_size;
178
179#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
180#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
181#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
182#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
183
984263bc 184/*
3f779080 185 * numdirtywakeup:
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186 *
187 * If someone is blocked due to there being too many dirty buffers,
188 * and numdirtybuffers is now reasonable, wake them up.
189 */
190
191static __inline void
192numdirtywakeup(int level)
193{
194 if (numdirtybuffers <= level) {
195 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
f832287e 196 spin_lock_wr(&needsbuffer_spin);
984263bc 197 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
f832287e 198 spin_unlock_wr(&needsbuffer_spin);
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199 wakeup(&needsbuffer);
200 }
201 }
202}
203
204/*
3f779080 205 * bufspacewakeup:
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206 *
207 * Called when buffer space is potentially available for recovery.
208 * getnewbuf() will block on this flag when it is unable to free
209 * sufficient buffer space. Buffer space becomes recoverable when
210 * bp's get placed back in the queues.
211 */
212
213static __inline void
214bufspacewakeup(void)
215{
216 /*
217 * If someone is waiting for BUF space, wake them up. Even
218 * though we haven't freed the kva space yet, the waiting
219 * process will be able to now.
220 */
221 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
f832287e 222 spin_lock_wr(&needsbuffer_spin);
984263bc 223 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
f832287e 224 spin_unlock_wr(&needsbuffer_spin);
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225 wakeup(&needsbuffer);
226 }
227}
228
229/*
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230 * runningbufwakeup:
231 *
232 * Accounting for I/O in progress.
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233 *
234 */
235static __inline void
236runningbufwakeup(struct buf *bp)
237{
238 if (bp->b_runningbufspace) {
239 runningbufspace -= bp->b_runningbufspace;
240 bp->b_runningbufspace = 0;
241 if (runningbufreq && runningbufspace <= lorunningspace) {
242 runningbufreq = 0;
243 wakeup(&runningbufreq);
244 }
245 }
246}
247
248/*
3f779080 249 * bufcountwakeup:
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250 *
251 * Called when a buffer has been added to one of the free queues to
252 * account for the buffer and to wakeup anyone waiting for free buffers.
253 * This typically occurs when large amounts of metadata are being handled
254 * by the buffer cache ( else buffer space runs out first, usually ).
255 */
256
257static __inline void
258bufcountwakeup(void)
259{
260 ++numfreebuffers;
261 if (needsbuffer) {
f832287e 262 spin_lock_wr(&needsbuffer_spin);
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263 needsbuffer &= ~VFS_BIO_NEED_ANY;
264 if (numfreebuffers >= hifreebuffers)
265 needsbuffer &= ~VFS_BIO_NEED_FREE;
f832287e 266 spin_unlock_wr(&needsbuffer_spin);
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267 wakeup(&needsbuffer);
268 }
269}
270
271/*
3f779080 272 * waitrunningbufspace()
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273 *
274 * runningbufspace is a measure of the amount of I/O currently
275 * running. This routine is used in async-write situations to
276 * prevent creating huge backups of pending writes to a device.
277 * Only asynchronous writes are governed by this function.
278 *
279 * Reads will adjust runningbufspace, but will not block based on it.
280 * The read load has a side effect of reducing the allowed write load.
281 *
282 * This does NOT turn an async write into a sync write. It waits
283 * for earlier writes to complete and generally returns before the
284 * caller's write has reached the device.
285 */
286static __inline void
287waitrunningbufspace(void)
288{
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289 if (runningbufspace > hirunningspace) {
290 crit_enter();
291 while (runningbufspace > hirunningspace) {
292 ++runningbufreq;
293 tsleep(&runningbufreq, 0, "wdrain", 0);
294 }
295 crit_exit();
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296 }
297}
298
299/*
3f779080 300 * vfs_buf_test_cache:
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301 *
302 * Called when a buffer is extended. This function clears the B_CACHE
303 * bit if the newly extended portion of the buffer does not contain
304 * valid data.
305 */
306static __inline__
307void
308vfs_buf_test_cache(struct buf *bp,
309 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
310 vm_page_t m)
311{
312 if (bp->b_flags & B_CACHE) {
313 int base = (foff + off) & PAGE_MASK;
314 if (vm_page_is_valid(m, base, size) == 0)
315 bp->b_flags &= ~B_CACHE;
316 }
317}
318
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319/*
320 * bd_wakeup:
321 *
322 * Wake up the buffer daemon if the number of outstanding dirty buffers
323 * is above specified threshold 'dirtybuflevel'.
324 *
325 * The buffer daemon is explicitly woken up when (a) the pending number
326 * of dirty buffers exceeds the recovery and stall mid-point value,
327 * (b) during bwillwrite() or (c) buf freelist was exhausted.
328 */
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329static __inline__
330void
331bd_wakeup(int dirtybuflevel)
332{
333 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
f832287e 334 spin_lock_wr(&needsbuffer_spin);
984263bc 335 bd_request = 1;
f832287e 336 spin_unlock_wr(&needsbuffer_spin);
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337 wakeup(&bd_request);
338 }
339}
340
341/*
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342 * bd_speedup:
343 *
344 * Speed up the buffer cache flushing process.
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345 */
346
347static __inline__
348void
349bd_speedup(void)
350{
351 bd_wakeup(1);
352}
353
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354/*
355 * bufinit:
356 *
357 * Load time initialisation of the buffer cache, called from machine
358 * dependant initialization code.
359 */
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360void
361bufinit(void)
362{
363 struct buf *bp;
b8bb0773 364 vm_offset_t bogus_offset;
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365 int i;
366
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367 spin_init(&needsbuffer_spin);
368
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369 /* next, make a null set of free lists */
370 for (i = 0; i < BUFFER_QUEUES; i++)
371 TAILQ_INIT(&bufqueues[i]);
372
373 /* finally, initialize each buffer header and stick on empty q */
374 for (i = 0; i < nbuf; i++) {
375 bp = &buf[i];
376 bzero(bp, sizeof *bp);
377 bp->b_flags = B_INVAL; /* we're just an empty header */
10f3fee5 378 bp->b_cmd = BUF_CMD_DONE;
b3098c79 379 bp->b_qindex = BQUEUE_EMPTY;
81b5c339 380 initbufbio(bp);
54f51aeb 381 xio_init(&bp->b_xio);
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382 LIST_INIT(&bp->b_dep);
383 BUF_LOCKINIT(bp);
b3098c79 384 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_EMPTY], bp, b_freelist);
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385 }
386
387 /*
388 * maxbufspace is the absolute maximum amount of buffer space we are
389 * allowed to reserve in KVM and in real terms. The absolute maximum
390 * is nominally used by buf_daemon. hibufspace is the nominal maximum
391 * used by most other processes. The differential is required to
392 * ensure that buf_daemon is able to run when other processes might
393 * be blocked waiting for buffer space.
394 *
395 * maxbufspace is based on BKVASIZE. Allocating buffers larger then
396 * this may result in KVM fragmentation which is not handled optimally
397 * by the system.
398 */
399 maxbufspace = nbuf * BKVASIZE;
400 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
401 lobufspace = hibufspace - MAXBSIZE;
402
403 lorunningspace = 512 * 1024;
404 hirunningspace = 1024 * 1024;
405
406/*
407 * Limit the amount of malloc memory since it is wired permanently into
408 * the kernel space. Even though this is accounted for in the buffer
409 * allocation, we don't want the malloced region to grow uncontrolled.
410 * The malloc scheme improves memory utilization significantly on average
411 * (small) directories.
412 */
413 maxbufmallocspace = hibufspace / 20;
414
415/*
416 * Reduce the chance of a deadlock occuring by limiting the number
417 * of delayed-write dirty buffers we allow to stack up.
418 */
419 hidirtybuffers = nbuf / 4 + 20;
420 numdirtybuffers = 0;
421/*
422 * To support extreme low-memory systems, make sure hidirtybuffers cannot
423 * eat up all available buffer space. This occurs when our minimum cannot
424 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
425 * BKVASIZE'd (8K) buffers.
426 */
427 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
428 hidirtybuffers >>= 1;
429 }
430 lodirtybuffers = hidirtybuffers / 2;
431
432/*
433 * Try to keep the number of free buffers in the specified range,
434 * and give special processes (e.g. like buf_daemon) access to an
435 * emergency reserve.
436 */
437 lofreebuffers = nbuf / 18 + 5;
438 hifreebuffers = 2 * lofreebuffers;
439 numfreebuffers = nbuf;
440
441/*
442 * Maximum number of async ops initiated per buf_daemon loop. This is
443 * somewhat of a hack at the moment, we really need to limit ourselves
444 * based on the number of bytes of I/O in-transit that were initiated
445 * from buf_daemon.
446 */
447
e4846942 448 bogus_offset = kmem_alloc_pageable(&kernel_map, PAGE_SIZE);
c439ad8f 449 bogus_page = vm_page_alloc(&kernel_object,
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450 (bogus_offset >> PAGE_SHIFT),
451 VM_ALLOC_NORMAL);
12e4aaff 452 vmstats.v_wire_count++;
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453
454}
455
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456/*
457 * Initialize the embedded bio structures
458 */
459void
460initbufbio(struct buf *bp)
461{
462 bp->b_bio1.bio_buf = bp;
463 bp->b_bio1.bio_prev = NULL;
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464 bp->b_bio1.bio_offset = NOOFFSET;
465 bp->b_bio1.bio_next = &bp->b_bio2;
466 bp->b_bio1.bio_done = NULL;
467
468 bp->b_bio2.bio_buf = bp;
469 bp->b_bio2.bio_prev = &bp->b_bio1;
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470 bp->b_bio2.bio_offset = NOOFFSET;
471 bp->b_bio2.bio_next = NULL;
472 bp->b_bio2.bio_done = NULL;
473}
474
475/*
476 * Reinitialize the embedded bio structures as well as any additional
477 * translation cache layers.
478 */
479void
480reinitbufbio(struct buf *bp)
481{
482 struct bio *bio;
483
484 for (bio = &bp->b_bio1; bio; bio = bio->bio_next) {
485 bio->bio_done = NULL;
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486 bio->bio_offset = NOOFFSET;
487 }
488}
489
490/*
491 * Push another BIO layer onto an existing BIO and return it. The new
492 * BIO layer may already exist, holding cached translation data.
493 */
494struct bio *
495push_bio(struct bio *bio)
496{
497 struct bio *nbio;
498
499 if ((nbio = bio->bio_next) == NULL) {
500 int index = bio - &bio->bio_buf->b_bio_array[0];
bbd44c71 501 if (index >= NBUF_BIO - 1) {
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502 panic("push_bio: too many layers bp %p\n",
503 bio->bio_buf);
504 }
505 nbio = &bio->bio_buf->b_bio_array[index + 1];
506 bio->bio_next = nbio;
507 nbio->bio_prev = bio;
508 nbio->bio_buf = bio->bio_buf;
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509 nbio->bio_offset = NOOFFSET;
510 nbio->bio_done = NULL;
511 nbio->bio_next = NULL;
512 }
513 KKASSERT(nbio->bio_done == NULL);
514 return(nbio);
515}
516
517void
518pop_bio(struct bio *bio)
519{
520 /* NOP */
521}
522
523void
524clearbiocache(struct bio *bio)
525{
526 while (bio) {
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527 bio->bio_offset = NOOFFSET;
528 bio = bio->bio_next;
529 }
530}
531
984263bc 532/*
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533 * bfreekva:
534 *
535 * Free the KVA allocation for buffer 'bp'.
984263bc 536 *
e43a034f 537 * Must be called from a critical section as this is the only locking for
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538 * buffer_map.
539 *
540 * Since this call frees up buffer space, we call bufspacewakeup().
541 */
542static void
312dcd01 543bfreekva(struct buf *bp)
984263bc 544{
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545 int count;
546
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547 if (bp->b_kvasize) {
548 ++buffreekvacnt;
a108bf71 549 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
e4846942 550 vm_map_lock(&buffer_map);
984263bc 551 bufspace -= bp->b_kvasize;
e4846942 552 vm_map_delete(&buffer_map,
984263bc 553 (vm_offset_t) bp->b_kvabase,
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554 (vm_offset_t) bp->b_kvabase + bp->b_kvasize,
555 &count
984263bc 556 );
e4846942 557 vm_map_unlock(&buffer_map);
a108bf71 558 vm_map_entry_release(count);
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559 bp->b_kvasize = 0;
560 bufspacewakeup();
561 }
562}
563
564/*
3f779080 565 * bremfree:
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566 *
567 * Remove the buffer from the appropriate free list.
568 */
569void
c8e4131d 570bremfree(struct buf *bp)
984263bc 571{
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572 int old_qindex;
573
574 crit_enter();
575 old_qindex = bp->b_qindex;
984263bc 576
b3098c79 577 if (bp->b_qindex != BQUEUE_NONE) {
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578 KASSERT(BUF_REFCNTNB(bp) == 1,
579 ("bremfree: bp %p not locked",bp));
984263bc 580 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
b3098c79 581 bp->b_qindex = BQUEUE_NONE;
984263bc 582 } else {
77bb9400 583 if (BUF_REFCNTNB(bp) <= 1)
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584 panic("bremfree: removing a buffer not on a queue");
585 }
586
587 /*
588 * Fixup numfreebuffers count. If the buffer is invalid or not
589 * delayed-write, and it was on the EMPTY, LRU, or AGE queues,
590 * the buffer was free and we must decrement numfreebuffers.
591 */
592 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
593 switch(old_qindex) {
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594 case BQUEUE_DIRTY:
595 case BQUEUE_CLEAN:
596 case BQUEUE_EMPTY:
597 case BQUEUE_EMPTYKVA:
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598 --numfreebuffers;
599 break;
600 default:
601 break;
602 }
603 }
e43a034f 604 crit_exit();
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605}
606
607
608/*
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609 * bread:
610 *
611 * Get a buffer with the specified data. Look in the cache first. We
612 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
613 * is set, the buffer is valid and we do not have to do anything ( see
614 * getblk() ).
984263bc
MD
615 */
616int
c8e4131d 617bread(struct vnode *vp, off_t loffset, int size, struct buf **bpp)
984263bc
MD
618{
619 struct buf *bp;
620
54078292 621 bp = getblk(vp, loffset, size, 0, 0);
984263bc
MD
622 *bpp = bp;
623
624 /* if not found in cache, do some I/O */
625 if ((bp->b_flags & B_CACHE) == 0) {
984263bc 626 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp));
984263bc 627 bp->b_flags &= ~(B_ERROR | B_INVAL);
10f3fee5
MD
628 bp->b_cmd = BUF_CMD_READ;
629 vfs_busy_pages(vp, bp);
81b5c339 630 vn_strategy(vp, &bp->b_bio1);
984263bc
MD
631 return (biowait(bp));
632 }
633 return (0);
634}
635
636/*
3f779080
HP
637 * breadn:
638 *
639 * Operates like bread, but also starts asynchronous I/O on
640 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior
641 * to initiating I/O . If B_CACHE is set, the buffer is valid
642 * and we do not have to do anything.
984263bc
MD
643 */
644int
a8f169e2 645breadn(struct vnode *vp, off_t loffset, int size, off_t *raoffset,
c8e4131d 646 int *rabsize, int cnt, struct buf **bpp)
984263bc
MD
647{
648 struct buf *bp, *rabp;
649 int i;
650 int rv = 0, readwait = 0;
651
54078292 652 *bpp = bp = getblk(vp, loffset, size, 0, 0);
984263bc
MD
653
654 /* if not found in cache, do some I/O */
655 if ((bp->b_flags & B_CACHE) == 0) {
984263bc 656 bp->b_flags &= ~(B_ERROR | B_INVAL);
10f3fee5
MD
657 bp->b_cmd = BUF_CMD_READ;
658 vfs_busy_pages(vp, bp);
81b5c339 659 vn_strategy(vp, &bp->b_bio1);
984263bc
MD
660 ++readwait;
661 }
662
54078292
MD
663 for (i = 0; i < cnt; i++, raoffset++, rabsize++) {
664 if (inmem(vp, *raoffset))
984263bc 665 continue;
54078292 666 rabp = getblk(vp, *raoffset, *rabsize, 0, 0);
984263bc
MD
667
668 if ((rabp->b_flags & B_CACHE) == 0) {
10f3fee5 669 rabp->b_flags |= B_ASYNC;
984263bc 670 rabp->b_flags &= ~(B_ERROR | B_INVAL);
10f3fee5
MD
671 rabp->b_cmd = BUF_CMD_READ;
672 vfs_busy_pages(vp, rabp);
984263bc 673 BUF_KERNPROC(rabp);
81b5c339 674 vn_strategy(vp, &rabp->b_bio1);
984263bc
MD
675 } else {
676 brelse(rabp);
677 }
678 }
679
680 if (readwait) {
681 rv = biowait(bp);
682 }
683 return (rv);
684}
685
686/*
3f779080
HP
687 * bwrite:
688 *
689 * Write, release buffer on completion. (Done by iodone
690 * if async). Do not bother writing anything if the buffer
691 * is invalid.
692 *
693 * Note that we set B_CACHE here, indicating that buffer is
694 * fully valid and thus cacheable. This is true even of NFS
695 * now so we set it generally. This could be set either here
696 * or in biodone() since the I/O is synchronous. We put it
697 * here.
984263bc
MD
698 */
699int
c8e4131d 700bwrite(struct buf *bp)
984263bc 701{
e43a034f 702 int oldflags;
984263bc
MD
703
704 if (bp->b_flags & B_INVAL) {
705 brelse(bp);
706 return (0);
707 }
708
709 oldflags = bp->b_flags;
710
77bb9400 711 if (BUF_REFCNTNB(bp) == 0)
984263bc 712 panic("bwrite: buffer is not busy???");
e43a034f 713 crit_enter();
984263bc
MD
714
715 /* Mark the buffer clean */
716 bundirty(bp);
717
10f3fee5 718 bp->b_flags &= ~B_ERROR;
6bae6177 719 bp->b_flags |= B_CACHE;
10f3fee5
MD
720 bp->b_cmd = BUF_CMD_WRITE;
721 vfs_busy_pages(bp->b_vp, bp);
984263bc
MD
722
723 /*
9a71d53f
MD
724 * Normal bwrites pipeline writes. NOTE: b_bufsize is only
725 * valid for vnode-backed buffers.
984263bc
MD
726 */
727 bp->b_runningbufspace = bp->b_bufsize;
728 runningbufspace += bp->b_runningbufspace;
729
e43a034f 730 crit_exit();
984263bc
MD
731 if (oldflags & B_ASYNC)
732 BUF_KERNPROC(bp);
81b5c339 733 vn_strategy(bp->b_vp, &bp->b_bio1);
984263bc
MD
734
735 if ((oldflags & B_ASYNC) == 0) {
736 int rtval = biowait(bp);
737 brelse(bp);
738 return (rtval);
739 } else if ((oldflags & B_NOWDRAIN) == 0) {
740 /*
741 * don't allow the async write to saturate the I/O
742 * system. Deadlocks can occur only if a device strategy
743 * routine (like in VN) turns around and issues another
744 * high-level write, in which case B_NOWDRAIN is expected
745 * to be set. Otherwise we will not deadlock here because
746 * we are blocking waiting for I/O that is already in-progress
747 * to complete.
748 */
749 waitrunningbufspace();
750 }
751
752 return (0);
753}
754
984263bc 755/*
3f779080
HP
756 * bdwrite:
757 *
758 * Delayed write. (Buffer is marked dirty). Do not bother writing
759 * anything if the buffer is marked invalid.
984263bc 760 *
3f779080
HP
761 * Note that since the buffer must be completely valid, we can safely
762 * set B_CACHE. In fact, we have to set B_CACHE here rather then in
763 * biodone() in order to prevent getblk from writing the buffer
764 * out synchronously.
984263bc
MD
765 */
766void
493c516a 767bdwrite(struct buf *bp)
984263bc 768{
77bb9400 769 if (BUF_REFCNTNB(bp) == 0)
984263bc
MD
770 panic("bdwrite: buffer is not busy");
771
772 if (bp->b_flags & B_INVAL) {
773 brelse(bp);
774 return;
775 }
776 bdirty(bp);
777
778 /*
779 * Set B_CACHE, indicating that the buffer is fully valid. This is
780 * true even of NFS now.
781 */
782 bp->b_flags |= B_CACHE;
783
784 /*
785 * This bmap keeps the system from needing to do the bmap later,
786 * perhaps when the system is attempting to do a sync. Since it
787 * is likely that the indirect block -- or whatever other datastructure
788 * that the filesystem needs is still in memory now, it is a good
789 * thing to do this. Note also, that if the pageout daemon is
790 * requesting a sync -- there might not be enough memory to do
791 * the bmap then... So, this is important to do.
792 */
54078292
MD
793 if (bp->b_bio2.bio_offset == NOOFFSET) {
794 VOP_BMAP(bp->b_vp, bp->b_loffset, NULL, &bp->b_bio2.bio_offset,
81b5c339 795 NULL, NULL);
984263bc
MD
796 }
797
798 /*
799 * Set the *dirty* buffer range based upon the VM system dirty pages.
800 */
801 vfs_setdirty(bp);
802
803 /*
804 * We need to do this here to satisfy the vnode_pager and the
805 * pageout daemon, so that it thinks that the pages have been
806 * "cleaned". Note that since the pages are in a delayed write
807 * buffer -- the VFS layer "will" see that the pages get written
808 * out on the next sync, or perhaps the cluster will be completed.
809 */
810 vfs_clean_pages(bp);
811 bqrelse(bp);
812
813 /*
814 * Wakeup the buffer flushing daemon if we have a lot of dirty
815 * buffers (midpoint between our recovery point and our stall
816 * point).
817 */
818 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
819
820 /*
821 * note: we cannot initiate I/O from a bdwrite even if we wanted to,
822 * due to the softdep code.
823 */
824}
825
826/*
3f779080 827 * bdirty:
984263bc 828 *
10f3fee5
MD
829 * Turn buffer into delayed write request by marking it B_DELWRI.
830 * B_RELBUF and B_NOCACHE must be cleared.
984263bc 831 *
10f3fee5
MD
832 * We reassign the buffer to itself to properly update it in the
833 * dirty/clean lists.
984263bc 834 *
10f3fee5
MD
835 * Since the buffer is not on a queue, we do not update the
836 * numfreebuffers count.
984263bc 837 *
e43a034f 838 * Must be called from a critical section.
b3098c79 839 * The buffer must be on BQUEUE_NONE.
984263bc
MD
840 */
841void
493c516a 842bdirty(struct buf *bp)
984263bc 843{
b3098c79 844 KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
69f8c926 845 if (bp->b_flags & B_NOCACHE) {
6ea70f76 846 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp);
69f8c926
MD
847 bp->b_flags &= ~B_NOCACHE;
848 }
849 if (bp->b_flags & B_INVAL) {
6ea70f76 850 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp);
69f8c926 851 }
10f3fee5 852 bp->b_flags &= ~B_RELBUF;
984263bc
MD
853
854 if ((bp->b_flags & B_DELWRI) == 0) {
10f3fee5 855 bp->b_flags |= B_DELWRI;
1f1ea522 856 reassignbuf(bp);
984263bc
MD
857 ++numdirtybuffers;
858 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
859 }
860}
861
862/*
3f779080 863 * bundirty:
984263bc
MD
864 *
865 * Clear B_DELWRI for buffer.
866 *
867 * Since the buffer is not on a queue, we do not update the numfreebuffers
868 * count.
869 *
e43a034f 870 * Must be called from a critical section.
eaaadca0 871 *
b3098c79 872 * The buffer is typically on BQUEUE_NONE but there is one case in
eaaadca0
MD
873 * brelse() that calls this function after placing the buffer on
874 * a different queue.
984263bc
MD
875 */
876
877void
493c516a 878bundirty(struct buf *bp)
984263bc 879{
984263bc
MD
880 if (bp->b_flags & B_DELWRI) {
881 bp->b_flags &= ~B_DELWRI;
1f1ea522 882 reassignbuf(bp);
984263bc
MD
883 --numdirtybuffers;
884 numdirtywakeup(lodirtybuffers);
885 }
886 /*
887 * Since it is now being written, we can clear its deferred write flag.
888 */
889 bp->b_flags &= ~B_DEFERRED;
890}
891
892/*
3f779080 893 * bawrite:
984263bc
MD
894 *
895 * Asynchronous write. Start output on a buffer, but do not wait for
896 * it to complete. The buffer is released when the output completes.
897 *
898 * bwrite() ( or the VOP routine anyway ) is responsible for handling
899 * B_INVAL buffers. Not us.
900 */
901void
c8e4131d 902bawrite(struct buf *bp)
984263bc
MD
903{
904 bp->b_flags |= B_ASYNC;
62cfda27 905 bwrite(bp);
984263bc
MD
906}
907
908/*
3f779080 909 * bowrite:
984263bc
MD
910 *
911 * Ordered write. Start output on a buffer, and flag it so that the
912 * device will write it in the order it was queued. The buffer is
913 * released when the output completes. bwrite() ( or the VOP routine
914 * anyway ) is responsible for handling B_INVAL buffers.
915 */
916int
c8e4131d 917bowrite(struct buf *bp)
984263bc
MD
918{
919 bp->b_flags |= B_ORDERED | B_ASYNC;
62cfda27 920 return (bwrite(bp));
984263bc
MD
921}
922
923/*
3f779080 924 * bwillwrite:
984263bc
MD
925 *
926 * Called prior to the locking of any vnodes when we are expecting to
927 * write. We do not want to starve the buffer cache with too many
928 * dirty buffers so we block here. By blocking prior to the locking
929 * of any vnodes we attempt to avoid the situation where a locked vnode
930 * prevents the various system daemons from flushing related buffers.
931 */
932
933void
934bwillwrite(void)
935{
936 if (numdirtybuffers >= hidirtybuffers) {
984263bc
MD
937 while (numdirtybuffers >= hidirtybuffers) {
938 bd_wakeup(1);
f832287e
MD
939 spin_lock_wr(&needsbuffer_spin);
940 if (numdirtybuffers >= hidirtybuffers) {
941 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
942 msleep(&needsbuffer, &needsbuffer_spin, 0,
943 "flswai", 0);
944 }
945 spin_unlock_wr(&needsbuffer_spin);
984263bc 946 }
984263bc
MD
947 }
948}
949
950/*
3f779080
HP
951 * buf_dirty_count_severe:
952 *
953 * Return true if we have too many dirty buffers.
984263bc
MD
954 */
955int
956buf_dirty_count_severe(void)
957{
958 return(numdirtybuffers >= hidirtybuffers);
959}
960
961/*
3f779080 962 * brelse:
984263bc
MD
963 *
964 * Release a busy buffer and, if requested, free its resources. The
965 * buffer will be stashed in the appropriate bufqueue[] allowing it
966 * to be accessed later as a cache entity or reused for other purposes.
967 */
968void
c8e4131d 969brelse(struct buf *bp)
984263bc 970{
9188c711
MD
971#ifdef INVARIANTS
972 int saved_flags = bp->b_flags;
973#endif
974
984263bc
MD
975 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
976
e43a034f 977 crit_enter();
984263bc 978
135bd6a8
MD
979 /*
980 * If B_NOCACHE is set we are being asked to destroy the buffer and
981 * its backing store. Clear B_DELWRI.
982 *
983 * B_NOCACHE is set in two cases: (1) when the caller really wants
984 * to destroy the buffer and backing store and (2) when the caller
985 * wants to destroy the buffer and backing store after a write
986 * completes.
987 */
988 if ((bp->b_flags & (B_NOCACHE|B_DELWRI)) == (B_NOCACHE|B_DELWRI)) {
989 bundirty(bp);
69f8c926
MD
990 }
991
984263bc
MD
992 if (bp->b_flags & B_LOCKED)
993 bp->b_flags &= ~B_ERROR;
994
135bd6a8
MD
995 /*
996 * If a write error occurs and the caller does not want to throw
997 * away the buffer, redirty the buffer. This will also clear
998 * B_NOCACHE.
999 */
10f3fee5
MD
1000 if (bp->b_cmd == BUF_CMD_WRITE &&
1001 (bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) {
984263bc
MD
1002 /*
1003 * Failed write, redirty. Must clear B_ERROR to prevent
1004 * pages from being scrapped. If B_INVAL is set then
1005 * this case is not run and the next case is run to
1006 * destroy the buffer. B_INVAL can occur if the buffer
1007 * is outside the range supported by the underlying device.
1008 */
1009 bp->b_flags &= ~B_ERROR;
1010 bdirty(bp);
10f3fee5
MD
1011 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) ||
1012 (bp->b_bufsize <= 0) || bp->b_cmd == BUF_CMD_FREEBLKS) {
984263bc
MD
1013 /*
1014 * Either a failed I/O or we were asked to free or not
1015 * cache the buffer.
1016 */
1017 bp->b_flags |= B_INVAL;
1018 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate)
1019 (*bioops.io_deallocate)(bp);
1020 if (bp->b_flags & B_DELWRI) {
1021 --numdirtybuffers;
1022 numdirtywakeup(lodirtybuffers);
1023 }
10f3fee5 1024 bp->b_flags &= ~(B_DELWRI | B_CACHE);
984263bc
MD
1025 }
1026
1027 /*
1028 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
1029 * is called with B_DELWRI set, the underlying pages may wind up
1030 * getting freed causing a previous write (bdwrite()) to get 'lost'
1031 * because pages associated with a B_DELWRI bp are marked clean.
1032 *
1033 * We still allow the B_INVAL case to call vfs_vmio_release(), even
1034 * if B_DELWRI is set.
1035 *
1036 * If B_DELWRI is not set we may have to set B_RELBUF if we are low
1037 * on pages to return pages to the VM page queues.
1038 */
1039 if (bp->b_flags & B_DELWRI)
1040 bp->b_flags &= ~B_RELBUF;
70371608 1041 else if (vm_page_count_severe())
984263bc
MD
1042 bp->b_flags |= B_RELBUF;
1043
9188c711
MD
1044 /*
1045 * At this point destroying the buffer is governed by the B_INVAL
1046 * or B_RELBUF flags.
1047 */
10f3fee5 1048 bp->b_cmd = BUF_CMD_DONE;
9188c711 1049
984263bc 1050 /*
135bd6a8
MD
1051 * VMIO buffer rundown. Make sure the VM page array is restored
1052 * after an I/O may have replaces some of the pages with bogus pages
1053 * in order to not destroy dirty pages in a fill-in read.
1054 *
1055 * Note that due to the code above, if a buffer is marked B_DELWRI
1056 * then the B_RELBUF and B_NOCACHE bits will always be clear.
1057 * B_INVAL may still be set, however.
984263bc 1058 *
135bd6a8
MD
1059 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer
1060 * but not the backing store. B_NOCACHE will destroy the backing
1061 * store.
984263bc 1062 *
135bd6a8
MD
1063 * Note that dirty NFS buffers contain byte-granular write ranges
1064 * and should not be destroyed w/ B_INVAL even if the backing store
1065 * is left intact.
984263bc 1066 */
135bd6a8 1067 if (bp->b_flags & B_VMIO) {
9188c711
MD
1068 /*
1069 * Rundown for VMIO buffers which are not dirty NFS buffers.
1070 */
984263bc
MD
1071 int i, j, resid;
1072 vm_page_t m;
1073 off_t foff;
1074 vm_pindex_t poff;
1075 vm_object_t obj;
1076 struct vnode *vp;
1077
1078 vp = bp->b_vp;
1079
1080 /*
1081 * Get the base offset and length of the buffer. Note that
1082 * in the VMIO case if the buffer block size is not
1083 * page-aligned then b_data pointer may not be page-aligned.
236b2b9f 1084 * But our b_xio.xio_pages array *IS* page aligned.
984263bc
MD
1085 *
1086 * block sizes less then DEV_BSIZE (usually 512) are not
1087 * supported due to the page granularity bits (m->valid,
1088 * m->dirty, etc...).
1089 *
1090 * See man buf(9) for more information
1091 */
1092
1093 resid = bp->b_bufsize;
81b5c339 1094 foff = bp->b_loffset;
984263bc 1095
54f51aeb
HP
1096 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1097 m = bp->b_xio.xio_pages[i];
984263bc
MD
1098 vm_page_flag_clear(m, PG_ZERO);
1099 /*
1100 * If we hit a bogus page, fixup *all* of them
06ecca5a
MD
1101 * now. Note that we left these pages wired
1102 * when we removed them so they had better exist,
1103 * and they cannot be ripped out from under us so
e43a034f 1104 * no critical section protection is necessary.
984263bc
MD
1105 */
1106 if (m == bogus_page) {
7540ab49 1107 obj = vp->v_object;
81b5c339 1108 poff = OFF_TO_IDX(bp->b_loffset);
984263bc 1109
54f51aeb 1110 for (j = i; j < bp->b_xio.xio_npages; j++) {
984263bc
MD
1111 vm_page_t mtmp;
1112
54f51aeb 1113 mtmp = bp->b_xio.xio_pages[j];
984263bc
MD
1114 if (mtmp == bogus_page) {
1115 mtmp = vm_page_lookup(obj, poff + j);
1116 if (!mtmp) {
fc92d4aa 1117 panic("brelse: page missing");
984263bc 1118 }
54f51aeb 1119 bp->b_xio.xio_pages[j] = mtmp;
984263bc
MD
1120 }
1121 }
1122
1123 if ((bp->b_flags & B_INVAL) == 0) {
54f51aeb
HP
1124 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
1125 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
984263bc 1126 }
54f51aeb 1127 m = bp->b_xio.xio_pages[i];
984263bc 1128 }
8d429613
MD
1129
1130 /*
1131 * Invalidate the backing store if B_NOCACHE is set
1132 * (e.g. used with vinvalbuf()). If this is NFS
1133 * we impose a requirement that the block size be
1134 * a multiple of PAGE_SIZE and create a temporary
1135 * hack to basically invalidate the whole page. The
1136 * problem is that NFS uses really odd buffer sizes
1137 * especially when tracking piecemeal writes and
1138 * it also vinvalbuf()'s a lot, which would result
1139 * in only partial page validation and invalidation
1140 * here. If the file page is mmap()'d, however,
1141 * all the valid bits get set so after we invalidate
1142 * here we would end up with weird m->valid values
1143 * like 0xfc. nfs_getpages() can't handle this so
1144 * we clear all the valid bits for the NFS case
1145 * instead of just some of them.
1146 *
1147 * The real bug is the VM system having to set m->valid
1148 * to VM_PAGE_BITS_ALL for faulted-in pages, which
1149 * itself is an artifact of the whole 512-byte
1150 * granular mess that exists to support odd block
1151 * sizes and UFS meta-data block sizes (e.g. 6144).
1152 * A complete rewrite is required.
1153 */
984263bc
MD
1154 if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
1155 int poffset = foff & PAGE_MASK;
8d429613
MD
1156 int presid;
1157
1158 presid = PAGE_SIZE - poffset;
1159 if (bp->b_vp->v_tag == VT_NFS &&
1160 bp->b_vp->v_type == VREG) {
1161 ; /* entire page */
1162 } else if (presid > resid) {
1163 presid = resid;
1164 }
984263bc
MD
1165 KASSERT(presid >= 0, ("brelse: extra page"));
1166 vm_page_set_invalid(m, poffset, presid);
1167 }
1168 resid -= PAGE_SIZE - (foff & PAGE_MASK);
1169 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
1170 }
984263bc
MD
1171 if (bp->b_flags & (B_INVAL | B_RELBUF))
1172 vfs_vmio_release(bp);
9188c711
MD
1173 } else {
1174 /*
1175 * Rundown for non-VMIO buffers.
1176 */
1177 if (bp->b_flags & (B_INVAL | B_RELBUF)) {
1178#if 0
1179 if (bp->b_vp)
6ea70f76 1180 kprintf("brelse bp %p %08x/%08x: Warning, caught and fixed brelvp bug\n", bp, saved_flags, bp->b_flags);
9188c711
MD
1181#endif
1182 if (bp->b_bufsize)
1183 allocbuf(bp, 0);
1184 if (bp->b_vp)
1185 brelvp(bp);
1186 }
984263bc
MD
1187 }
1188
b3098c79 1189 if (bp->b_qindex != BQUEUE_NONE)
984263bc 1190 panic("brelse: free buffer onto another queue???");
77bb9400 1191 if (BUF_REFCNTNB(bp) > 1) {
984263bc
MD
1192 /* Temporary panic to verify exclusive locking */
1193 /* This panic goes away when we allow shared refs */
1194 panic("brelse: multiple refs");
1195 /* do not release to free list */
1196 BUF_UNLOCK(bp);
e43a034f 1197 crit_exit();
984263bc
MD
1198 return;
1199 }
1200
9188c711
MD
1201 /*
1202 * Figure out the correct queue to place the cleaned up buffer on.
1203 * Buffers placed in the EMPTY or EMPTYKVA had better already be
1204 * disassociated from their vnode.
1205 */
984263bc 1206
984263bc 1207 if (bp->b_bufsize == 0) {
9188c711
MD
1208 /*
1209 * Buffers with no memory. Due to conditionals near the top
1210 * of brelse() such buffers should probably already be
1211 * marked B_INVAL and disassociated from their vnode.
1212 */
984263bc 1213 bp->b_flags |= B_INVAL;
54078292 1214 KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp));
1f1ea522 1215 KKASSERT((bp->b_flags & B_HASHED) == 0);
984263bc 1216 if (bp->b_kvasize) {
b3098c79 1217 bp->b_qindex = BQUEUE_EMPTYKVA;
984263bc 1218 } else {
b3098c79 1219 bp->b_qindex = BQUEUE_EMPTY;
984263bc
MD
1220 }
1221 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
984263bc 1222 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) {
9188c711
MD
1223 /*
1224 * Buffers with junk contents. Again these buffers had better
1225 * already be disassociated from their vnode.
1226 */
54078292 1227 KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp));
1f1ea522 1228 KKASSERT((bp->b_flags & B_HASHED) == 0);
984263bc 1229 bp->b_flags |= B_INVAL;
b3098c79
HP
1230 bp->b_qindex = BQUEUE_CLEAN;
1231 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
984263bc 1232 } else if (bp->b_flags & B_LOCKED) {
9188c711
MD
1233 /*
1234 * Buffers that are locked.
1235 */
b3098c79
HP
1236 bp->b_qindex = BQUEUE_LOCKED;
1237 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist);
984263bc 1238 } else {
9188c711
MD
1239 /*
1240 * Remaining buffers. These buffers are still associated with
1241 * their vnode.
1242 */
984263bc
MD
1243 switch(bp->b_flags & (B_DELWRI|B_AGE)) {
1244 case B_DELWRI | B_AGE:
b3098c79
HP
1245 bp->b_qindex = BQUEUE_DIRTY;
1246 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_DIRTY], bp, b_freelist);
984263bc
MD
1247 break;
1248 case B_DELWRI:
b3098c79
HP
1249 bp->b_qindex = BQUEUE_DIRTY;
1250 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist);
984263bc
MD
1251 break;
1252 case B_AGE:
b3098c79
HP
1253 bp->b_qindex = BQUEUE_CLEAN;
1254 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
984263bc
MD
1255 break;
1256 default:
b3098c79
HP
1257 bp->b_qindex = BQUEUE_CLEAN;
1258 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
984263bc
MD
1259 break;
1260 }
1261 }
1262
1263 /*
1264 * If B_INVAL, clear B_DELWRI. We've already placed the buffer
1265 * on the correct queue.
1266 */
1267 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI))
1268 bundirty(bp);
1269
1270 /*
1271 * Fixup numfreebuffers count. The bp is on an appropriate queue
1272 * unless locked. We then bump numfreebuffers if it is not B_DELWRI.
1273 * We've already handled the B_INVAL case ( B_DELWRI will be clear
1274 * if B_INVAL is set ).
1275 */
984263bc
MD
1276 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI))
1277 bufcountwakeup();
1278
1279 /*
1280 * Something we can maybe free or reuse
1281 */
1282 if (bp->b_bufsize || bp->b_kvasize)
1283 bufspacewakeup();
1284
69f8c926
MD
1285 /*
1286 * Clean up temporary flags and unlock the buffer.
1287 */
984263bc
MD
1288 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF |
1289 B_DIRECT | B_NOWDRAIN);
69f8c926 1290 BUF_UNLOCK(bp);
e43a034f 1291 crit_exit();
984263bc
MD
1292}
1293
1294/*
3f779080
HP
1295 * bqrelse:
1296 *
1297 * Release a buffer back to the appropriate queue but do not try to free
1298 * it. The buffer is expected to be used again soon.
984263bc 1299 *
3f779080
HP
1300 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by
1301 * biodone() to requeue an async I/O on completion. It is also used when
1302 * known good buffers need to be requeued but we think we may need the data
1303 * again soon.
984263bc 1304 *
3f779080 1305 * XXX we should be able to leave the B_RELBUF hint set on completion.
984263bc
MD
1306 */
1307void
c8e4131d 1308bqrelse(struct buf *bp)
984263bc 1309{
e43a034f 1310 crit_enter();
984263bc
MD
1311
1312 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
1313
b3098c79 1314 if (bp->b_qindex != BQUEUE_NONE)
984263bc 1315 panic("bqrelse: free buffer onto another queue???");
77bb9400 1316 if (BUF_REFCNTNB(bp) > 1) {
984263bc
MD
1317 /* do not release to free list */
1318 panic("bqrelse: multiple refs");
1319 BUF_UNLOCK(bp);
e43a034f 1320 crit_exit();
984263bc
MD
1321 return;
1322 }
1323 if (bp->b_flags & B_LOCKED) {
1324 bp->b_flags &= ~B_ERROR;
b3098c79
HP
1325 bp->b_qindex = BQUEUE_LOCKED;
1326 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist);
984263bc
MD
1327 /* buffers with stale but valid contents */
1328 } else if (bp->b_flags & B_DELWRI) {
b3098c79
HP
1329 bp->b_qindex = BQUEUE_DIRTY;
1330 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist);
984263bc
MD
1331 } else if (vm_page_count_severe()) {
1332 /*
1333 * We are too low on memory, we have to try to free the
1334 * buffer (most importantly: the wired pages making up its
1335 * backing store) *now*.
1336 */
e43a034f 1337 crit_exit();
984263bc
MD
1338 brelse(bp);
1339 return;
1340 } else {
b3098c79
HP
1341 bp->b_qindex = BQUEUE_CLEAN;
1342 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist);
984263bc
MD
1343 }
1344
1345 if ((bp->b_flags & B_LOCKED) == 0 &&
1346 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) {
1347 bufcountwakeup();
1348 }
1349
1350 /*
1351 * Something we can maybe free or reuse.
1352 */
1353 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
1354 bufspacewakeup();
1355
9188c711
MD
1356 /*
1357 * Final cleanup and unlock. Clear bits that are only used while a
1358 * buffer is actively locked.
1359 */
984263bc 1360 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
9188c711 1361 BUF_UNLOCK(bp);
e43a034f 1362 crit_exit();
984263bc
MD
1363}
1364
3f779080
HP
1365/*
1366 * vfs_vmio_release:
1367 *
1368 * Return backing pages held by the buffer 'bp' back to the VM system
1369 * if possible. The pages are freed if they are no longer valid or
1370 * attempt to free if it was used for direct I/O otherwise they are
1371 * sent to the page cache.
1372 *
1373 * Pages that were marked busy are left alone and skipped.
1374 *
1375 * The KVA mapping (b_data) for the underlying pages is removed by
1376 * this function.
1377 */
984263bc 1378static void
493c516a 1379vfs_vmio_release(struct buf *bp)
984263bc 1380{
e43a034f 1381 int i;
984263bc
MD
1382 vm_page_t m;
1383
e43a034f 1384 crit_enter();
54f51aeb
HP
1385 for (i = 0; i < bp->b_xio.xio_npages; i++) {
1386 m = bp->b_xio.xio_pages[i];
1387 bp->b_xio.xio_pages[i] = NULL;
984263bc
MD
1388 /*
1389 * In order to keep page LRU ordering consistent, put
1390 * everything on the inactive queue.
1391 */
1392 vm_page_unwire(m, 0);
1393 /*
1394 * We don't mess with busy pages, it is
1395 * the responsibility of the process that
1396 * busied the pages to deal with them.
1397 */
1398 if ((m->flags & PG_BUSY) || (m->busy != 0))
1399 continue;
1400
1401 if (m->wire_count == 0) {
1402 vm_page_flag_clear(m, PG_ZERO);
1403 /*
1404 * Might as well free the page if we can and it has
1405 * no valid data. We also free the page if the
1406 * buffer was used for direct I/O.
1407 */
3f779080
HP
1408 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
1409 m->hold_count == 0) {
984263bc
MD
1410 vm_page_busy(m);
1411 vm_page_protect(m, VM_PROT_NONE);
1412 vm_page_free(m);
1413 } else if (bp->b_flags & B_DIRECT) {
1414 vm_page_try_to_free(m);
1415 } else if (vm_page_count_severe()) {
1416 vm_page_try_to_cache(m);
1417 }
1418 }
1419 }
e43a034f 1420 crit_exit();
54f51aeb 1421 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
984263bc
MD
1422 if (bp->b_bufsize) {
1423 bufspacewakeup();
1424 bp->b_bufsize = 0;
1425 }
54f51aeb 1426 bp->b_xio.xio_npages = 0;
984263bc
MD
1427 bp->b_flags &= ~B_VMIO;
1428 if (bp->b_vp)
1429 brelvp(bp);
1430}
1431
984263bc 1432/*
3f779080 1433 * vfs_bio_awrite:
984263bc
MD
1434 *
1435 * Implement clustered async writes for clearing out B_DELWRI buffers.
1436 * This is much better then the old way of writing only one buffer at
1437 * a time. Note that we may not be presented with the buffers in the
1438 * correct order, so we search for the cluster in both directions.
6f68d895
MD
1439 *
1440 * The buffer is locked on call.
984263bc
MD
1441 */
1442int
6f68d895 1443vfs_bio_awrite(struct buf *bp)
984263bc
MD
1444{
1445 int i;
1446 int j;
54078292 1447 off_t loffset = bp->b_loffset;
984263bc 1448 struct vnode *vp = bp->b_vp;
54078292 1449 int nbytes;
984263bc
MD
1450 struct buf *bpa;
1451 int nwritten;
1452 int size;
984263bc 1453
e43a034f 1454 crit_enter();
984263bc
MD
1455 /*
1456 * right now we support clustered writing only to regular files. If
1457 * we find a clusterable block we could be in the middle of a cluster
1458 * rather then at the beginning.
81b5c339 1459 *
54078292
MD
1460 * NOTE: b_bio1 contains the logical loffset and is aliased
1461 * to b_loffset. b_bio2 contains the translated block number.
984263bc
MD
1462 */
1463 if ((vp->v_type == VREG) &&
1464 (vp->v_mount != 0) && /* Only on nodes that have the size info */
1465 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
1466
1467 size = vp->v_mount->mnt_stat.f_iosize;
984263bc 1468
54078292
MD
1469 for (i = size; i < MAXPHYS; i += size) {
1470 if ((bpa = findblk(vp, loffset + i)) &&
984263bc
MD
1471 BUF_REFCNT(bpa) == 0 &&
1472 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1473 (B_DELWRI | B_CLUSTEROK)) &&
1474 (bpa->b_bufsize == size)) {
54078292
MD
1475 if ((bpa->b_bio2.bio_offset == NOOFFSET) ||
1476 (bpa->b_bio2.bio_offset !=
1477 bp->b_bio2.bio_offset + i))
984263bc
MD
1478 break;
1479 } else {
1480 break;
1481 }
1482 }
54078292
MD
1483 for (j = size; i + j <= MAXPHYS && j <= loffset; j += size) {
1484 if ((bpa = findblk(vp, loffset - j)) &&
984263bc
MD
1485 BUF_REFCNT(bpa) == 0 &&
1486 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
1487 (B_DELWRI | B_CLUSTEROK)) &&
1488 (bpa->b_bufsize == size)) {
54078292
MD
1489 if ((bpa->b_bio2.bio_offset == NOOFFSET) ||
1490 (bpa->b_bio2.bio_offset !=
1491 bp->b_bio2.bio_offset - j))
984263bc
MD
1492 break;
1493 } else {
1494 break;
1495 }
1496 }
54078292
MD
1497 j -= size;
1498 nbytes = (i + j);
984263bc
MD
1499 /*
1500 * this is a possible cluster write
1501 */
54078292 1502 if (nbytes != size) {
6f68d895 1503 BUF_UNLOCK(bp);
54078292
MD
1504 nwritten = cluster_wbuild(vp, size,
1505 loffset - j, nbytes);
e43a034f 1506 crit_exit();
984263bc
MD
1507 return nwritten;
1508 }
1509 }
1510
984263bc
MD
1511 bremfree(bp);
1512 bp->b_flags |= B_ASYNC;
1513
e43a034f 1514 crit_exit();
984263bc
MD
1515 /*
1516 * default (old) behavior, writing out only one block
1517 *
1518 * XXX returns b_bufsize instead of b_bcount for nwritten?
1519 */
1520 nwritten = bp->b_bufsize;
62cfda27 1521 bwrite(bp);
984263bc
MD
1522
1523 return nwritten;
1524}
1525
1526/*
3f779080 1527 * getnewbuf:
984263bc
MD
1528 *
1529 * Find and initialize a new buffer header, freeing up existing buffers
1530 * in the bufqueues as necessary. The new buffer is returned locked.
1531 *
1532 * Important: B_INVAL is not set. If the caller wishes to throw the
1533 * buffer away, the caller must set B_INVAL prior to calling brelse().
1534 *
1535 * We block if:
1536 * We have insufficient buffer headers
1537 * We have insufficient buffer space
1538 * buffer_map is too fragmented ( space reservation fails )
1539 * If we have to flush dirty buffers ( but we try to avoid this )
1540 *
1541 * To avoid VFS layer recursion we do not flush dirty buffers ourselves.
1542 * Instead we ask the buf daemon to do it for us. We attempt to
1543 * avoid piecemeal wakeups of the pageout daemon.
1544 */
1545
1546static struct buf *
1547getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
1548{
1549 struct buf *bp;
1550 struct buf *nbp;
1551 int defrag = 0;
1552 int nqindex;
1553 static int flushingbufs;
1554
1555 /*
1556 * We can't afford to block since we might be holding a vnode lock,
1557 * which may prevent system daemons from running. We deal with
1558 * low-memory situations by proactively returning memory and running
1559 * async I/O rather then sync I/O.
1560 */
1561
1562 ++getnewbufcalls;
1563 --getnewbufrestarts;
1564restart:
1565 ++getnewbufrestarts;
1566
1567 /*
1568 * Setup for scan. If we do not have enough free buffers,
1569 * we setup a degenerate case that immediately fails. Note
1570 * that if we are specially marked process, we are allowed to
1571 * dip into our reserves.
1572 *
1573 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
1574 *
1575 * We start with EMPTYKVA. If the list is empty we backup to EMPTY.
1576 * However, there are a number of cases (defragging, reusing, ...)
1577 * where we cannot backup.
1578 */
b3098c79
HP
1579 nqindex = BQUEUE_EMPTYKVA;
1580 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]);
984263bc
MD
1581
1582 if (nbp == NULL) {
1583 /*
1584 * If no EMPTYKVA buffers and we are either
1585 * defragging or reusing, locate a CLEAN buffer
1586 * to free or reuse. If bufspace useage is low
1587 * skip this step so we can allocate a new buffer.
1588 */
1589 if (defrag || bufspace >= lobufspace) {
b3098c79
HP
1590 nqindex = BQUEUE_CLEAN;
1591 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]);
984263bc
MD
1592 }
1593
1594 /*
1595 * If we could not find or were not allowed to reuse a
1596 * CLEAN buffer, check to see if it is ok to use an EMPTY
1597 * buffer. We can only use an EMPTY buffer if allocating
1598 * its KVA would not otherwise run us out of buffer space.
1599 */
1600 if (nbp == NULL && defrag == 0 &&
1601 bufspace + maxsize < hibufspace) {
b3098c79
HP
1602 nqindex = BQUEUE_EMPTY;
1603 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]);
984263bc
MD
1604 }
1605 }
1606
1607 /*
1608 * Run scan, possibly freeing data and/or kva mappings on the fly
1609 * depending.
1610 */
1611
1612 while ((bp = nbp) != NULL) {
1613 int qindex = nqindex;
1614
1615 /*
1616 * Calculate next bp ( we can only use it if we do not block
1617 * or do other fancy things ).
1618 */
1619 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
1620 switch(qindex) {
b3098c79
HP
1621 case BQUEUE_EMPTY:
1622 nqindex = BQUEUE_EMPTYKVA;
1623 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA])))
984263bc
MD
1624 break;
1625 /* fall through */
b3098c79
HP
1626 case BQUEUE_EMPTYKVA:
1627 nqindex = BQUEUE_CLEAN;
1628 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN])))
984263bc
MD
1629 break;
1630 /* fall through */
b3098c79 1631 case BQUEUE_CLEAN:
984263bc
MD
1632 /*
1633 * nbp is NULL.
1634 */
1635 break;
1636 }
1637 }
1638
1639 /*
1640 * Sanity Checks
1641 */
1642 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
1643
1644 /*
1645 * Note: we no longer distinguish between VMIO and non-VMIO
1646 * buffers.
1647 */
1648
1649 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
1650
1651 /*
1652 * If we are defragging then we need a buffer with
1653 * b_kvasize != 0. XXX this situation should no longer
1654 * occur, if defrag is non-zero the buffer's b_kvasize
1655 * should also be non-zero at this point. XXX
1656 */
1657 if (defrag && bp->b_kvasize == 0) {
6ea70f76 1658 kprintf("Warning: defrag empty buffer %p\n", bp);
984263bc
MD
1659 continue;
1660 }
1661
1662 /*
1663 * Start freeing the bp. This is somewhat involved. nbp
b3098c79 1664 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers
9188c711
MD
1665 * on the clean list must be disassociated from their
1666 * current vnode. Buffers on the empty[kva] lists have
1667 * already been disassociated.
984263bc
MD
1668 */
1669
d9dba6f6 1670 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) {
6ea70f76 1671 kprintf("getnewbuf: warning, locked buf %p, race corrected\n", bp);
d9dba6f6
MD
1672 tsleep(&bd_request, 0, "gnbxxx", hz / 100);
1673 goto restart;
1674 }
1675 if (bp->b_qindex != qindex) {
6ea70f76 1676 kprintf("getnewbuf: warning, BUF_LOCK blocked unexpectedly on buf %p index %d->%d, race corrected\n", bp, qindex, bp->b_qindex);
d9dba6f6
MD
1677 BUF_UNLOCK(bp);
1678 goto restart;
1679 }
984263bc
MD
1680 bremfree(bp);
1681
b3098c79 1682 if (qindex == BQUEUE_CLEAN) {
984263bc
MD
1683 if (bp->b_flags & B_VMIO) {
1684 bp->b_flags &= ~B_ASYNC;
1685 vfs_vmio_release(bp);
1686 }
1687 if (bp->b_vp)
1688 brelvp(bp);
1689 }
1690
1691 /*
1692 * NOTE: nbp is now entirely invalid. We can only restart
1693 * the scan from this point on.
1694 *
1695 * Get the rest of the buffer freed up. b_kva* is still
1696 * valid after this operation.
1697 */
1698
54078292 1699 KASSERT(bp->b_vp == NULL, ("bp3 %p flags %08x vnode %p qindex %d unexpectededly still associated!", bp, bp->b_flags, bp->b_vp, qindex));
1f1ea522 1700 KKASSERT((bp->b_flags & B_HASHED) == 0);
984263bc
MD
1701 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate)
1702 (*bioops.io_deallocate)(bp);
984263bc 1703
06ecca5a 1704 /*
e43a034f
MD
1705 * critical section protection is not required when
1706 * scrapping a buffer's contents because it is already
1707 * wired.
06ecca5a 1708 */
984263bc
MD
1709 if (bp->b_bufsize)
1710 allocbuf(bp, 0);
1711
4414f2c9 1712 bp->b_flags = B_BNOCLIP;
10f3fee5 1713 bp->b_cmd = BUF_CMD_DONE;
984263bc 1714 bp->b_vp = NULL;
984263bc
MD
1715 bp->b_error = 0;
1716 bp->b_resid = 0;
1717 bp->b_bcount = 0;
54f51aeb 1718 bp->b_xio.xio_npages = 0;
984263bc 1719 bp->b_dirtyoff = bp->b_dirtyend = 0;
81b5c339 1720 reinitbufbio(bp);
984263bc
MD
1721
1722 LIST_INIT(&bp->b_dep);
1723
1724 /*
1725 * If we are defragging then free the buffer.
1726 */
1727 if (defrag) {
1728 bp->b_flags |= B_INVAL;
1729 bfreekva(bp);
1730 brelse(bp);
1731 defrag = 0;
1732 goto restart;
1733 }
1734
1735 /*
1736 * If we are overcomitted then recover the buffer and its
1737 * KVM space. This occurs in rare situations when multiple
1738 * processes are blocked in getnewbuf() or allocbuf().
1739 */
1740 if (bufspace >= hibufspace)
1741 flushingbufs = 1;
1742 if (flushingbufs && bp->b_kvasize != 0) {
1743 bp->b_flags |= B_INVAL;
1744 bfreekva(bp);
1745 brelse(bp);
1746 goto restart;
1747 }
1748 if (bufspace < lobufspace)
1749 flushingbufs = 0;
1750 break;
1751 }
1752
1753 /*
1754 * If we exhausted our list, sleep as appropriate. We may have to
1755 * wakeup various daemons and write out some dirty buffers.
1756 *
1757 * Generally we are sleeping due to insufficient buffer space.
1758 */
1759
1760 if (bp == NULL) {
1761 int flags;
1762 char *waitmsg;
1763
1764 if (defrag) {
1765 flags = VFS_BIO_NEED_BUFSPACE;
1766 waitmsg = "nbufkv";
1767 } else if (bufspace >= hibufspace) {
1768 waitmsg = "nbufbs";
1769 flags = VFS_BIO_NEED_BUFSPACE;
1770 } else {
1771 waitmsg = "newbuf";
1772 flags = VFS_BIO_NEED_ANY;
1773 }
1774
1775 bd_speedup(); /* heeeelp */
1776
1777 needsbuffer |= flags;
1778 while (needsbuffer & flags) {
377d4740 1779 if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo))
984263bc
MD
1780 return (NULL);
1781 }
1782 } else {
1783 /*
1784 * We finally have a valid bp. We aren't quite out of the
1785 * woods, we still have to reserve kva space. In order
1786 * to keep fragmentation sane we only allocate kva in
1787 * BKVASIZE chunks.
1788 */
1789 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
1790
1791 if (maxsize != bp->b_kvasize) {
1792 vm_offset_t addr = 0;
a108bf71 1793 int count;
984263bc
MD
1794
1795 bfreekva(bp);
1796
a108bf71 1797 count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
e4846942 1798 vm_map_lock(&buffer_map);
984263bc 1799
e4846942
MD
1800 if (vm_map_findspace(&buffer_map,
1801 vm_map_min(&buffer_map), maxsize,
e9bb90e8 1802 maxsize, &addr)) {
984263bc 1803 /*
3f779080 1804 * Uh oh. Buffer map is too fragmented. We
984263bc
MD
1805 * must defragment the map.
1806 */
e4846942 1807 vm_map_unlock(&buffer_map);
a108bf71 1808 vm_map_entry_release(count);
984263bc
MD
1809 ++bufdefragcnt;
1810 defrag = 1;
1811 bp->b_flags |= B_INVAL;
1812 brelse(bp);
1813 goto restart;
1814 }
1815 if (addr) {
e4846942 1816 vm_map_insert(&buffer_map, &count,
a108bf71 1817 NULL, 0,
984263bc 1818 addr, addr + maxsize,
1b874851
MD
1819 VM_MAPTYPE_NORMAL,
1820 VM_PROT_ALL, VM_PROT_ALL,
1821 MAP_NOFAULT);
984263bc
MD
1822
1823 bp->b_kvabase = (caddr_t) addr;
1824 bp->b_kvasize = maxsize;
1825 bufspace += bp->b_kvasize;
1826 ++bufreusecnt;
1827 }
e4846942 1828 vm_map_unlock(&buffer_map);
a108bf71 1829 vm_map_entry_release(count);
984263bc
MD
1830 }
1831 bp->b_data = bp->b_kvabase;
1832 }
1833 return(bp);
1834}
1835
1836/*
3f779080 1837 * buf_daemon:
984263bc 1838 *
3f779080 1839 * Buffer flushing daemon. Buffers are normally flushed by the
984263bc
MD
1840 * update daemon but if it cannot keep up this process starts to
1841 * take the load in an attempt to prevent getnewbuf() from blocking.
1842 */
1843
bc6dffab 1844static struct thread *bufdaemonthread;
984263bc
MD
1845
1846static struct kproc_desc buf_kp = {
1847 "bufdaemon",
1848 buf_daemon,
bc6dffab 1849 &bufdaemonthread
984263bc
MD
1850};
1851SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
1852
1853static void
c972a82f 1854buf_daemon(void)
984263bc 1855{
984263bc
MD
1856 /*
1857 * This process needs to be suspended prior to shutdown sync.
1858 */
bc6dffab
MD
1859 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc,
1860 bufdaemonthread, SHUTDOWN_PRI_LAST);
984263bc
MD
1861
1862 /*
1863 * This process is allowed to take the buffer cache to the limit
1864 */
e43a034f 1865 crit_enter();
984263bc
MD
1866
1867 for (;;) {
0cfcada1 1868 kproc_suspend_loop();
984263bc
MD
1869
1870 /*
1871 * Do the flush. Limit the amount of in-transit I/O we
1872 * allow to build up, otherwise we would completely saturate
1873 * the I/O system. Wakeup any waiting processes before we
1874 * normally would so they can run in parallel with our drain.
1875 */
1876 while (numdirtybuffers > lodirtybuffers) {
1877 if (flushbufqueues() == 0)
1878 break;
1879 waitrunningbufspace();
1880 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
1881 }
1882
1883 /*
1884 * Only clear bd_request if we have reached our low water
1885 * mark. The buf_daemon normally waits 5 seconds and
1886 * then incrementally flushes any dirty buffers that have
1887 * built up, within reason.
1888 *
1889 * If we were unable to hit our low water mark and couldn't
1890 * find any flushable buffers, we sleep half a second.
1891 * Otherwise we loop immediately.
1892 */
1893 if (numdirtybuffers <= lodirtybuffers) {
1894 /*
1895 * We reached our low water mark, reset the
1896 * request and sleep until we are needed again.
1897 * The sleep is just so the suspend code works.
1898 */
f832287e 1899 spin_lock_wr(&needsbuffer_spin);
984263bc 1900 bd_request = 0;
f832287e
MD
1901 msleep(&bd_request, &needsbuffer_spin, 0, "psleep", hz);
1902 spin_unlock_wr(&needsbuffer_spin);
984263bc
MD
1903 } else {
1904 /*
1905 * We couldn't find any flushable dirty buffers but
1906 * still have too many dirty buffers, we
1907 * have to sleep and try again. (rare)
1908 */
377d4740 1909 tsleep(&bd_request, 0, "qsleep", hz / 2);
984263bc
MD
1910 }
1911 }
1912}
1913
1914/*
3f779080 1915 * flushbufqueues:
984263bc
MD
1916 *
1917 * Try to flush a buffer in the dirty queue. We must be careful to
1918 * free up B_INVAL buffers instead of write them, which NFS is
1919 * particularly sensitive to.
1920 */
1921
1922static int
1923flushbufqueues(void)
1924{
1925 struct buf *bp;
1926 int r = 0;
1927
b3098c79 1928 bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]);
984263bc
MD
1929
1930 while (bp) {
1931 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp));
70371608 1932 if (bp->b_flags & B_DELWRI) {
984263bc
MD
1933 if (bp->b_flags & B_INVAL) {
1934 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0)
1935 panic("flushbufqueues: locked buf");
1936 bremfree(bp);
1937 brelse(bp);
1938 ++r;
1939 break;
1940 }
1941 if (LIST_FIRST(&bp->b_dep) != NULL &&
1942 bioops.io_countdeps &&
1943 (bp->b_flags & B_DEFERRED) == 0 &&
1944 (*bioops.io_countdeps)(bp, 0)) {
b3098c79 1945 TAILQ_REMOVE(&bufqueues[BQUEUE_DIRTY],
6f68d895 1946 bp, b_freelist);
b3098c79 1947 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY],
6f68d895 1948 bp, b_freelist);
984263bc 1949 bp->b_flags |= B_DEFERRED;
b3098c79 1950 bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]);
984263bc
MD
1951 continue;
1952 }
6f68d895
MD
1953
1954 /*
1955 * Only write it out if we can successfully lock
1956 * it.
1957 */
1958 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) == 0) {
1959 vfs_bio_awrite(bp);
1960 ++r;
1961 break;
1962 }
984263bc
MD
1963 }
1964 bp = TAILQ_NEXT(bp, b_freelist);
1965 }
1966 return (r);
1967}
1968
984263bc 1969/*
3f779080
HP
1970 * inmem:
1971 *
1972 * Returns true if no I/O is needed to access the associated VM object.
1f1ea522 1973 * This is like findblk except it also hunts around in the VM system for
3f779080 1974 * the data.
06ecca5a 1975 *
3f779080
HP
1976 * Note that we ignore vm_page_free() races from interrupts against our
1977 * lookup, since if the caller is not protected our return value will not
1978 * be any more valid then otherwise once we exit the critical section.
984263bc 1979 */
984263bc 1980int
54078292 1981inmem(struct vnode *vp, off_t loffset)
984263bc
MD
1982{
1983 vm_object_t obj;
1984 vm_offset_t toff, tinc, size;
1985 vm_page_t m;
984263bc 1986
54078292 1987 if (findblk(vp, loffset))
984263bc
MD
1988 return 1;
1989 if (vp->v_mount == NULL)
1990 return 0;
7540ab49
MD
1991 if ((obj = vp->v_object) == NULL)
1992 return 0;
984263bc
MD
1993
1994 size = PAGE_SIZE;
1995 if (size > vp->v_mount->mnt_stat.f_iosize)
1996 size = vp->v_mount->mnt_stat.f_iosize;
984263bc
MD
1997
1998 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
54078292
MD
1999 m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff));
2000 if (m == NULL)
984263bc
MD
2001 return 0;
2002 tinc = size;
54078292
MD
2003 if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK))
2004 tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK);
984263bc 2005 if (vm_page_is_valid(m,
54078292 2006 (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0)
984263bc
MD
2007 return 0;
2008 }
2009 return 1;
2010}
2011
2012/*
3f779080 2013 * vfs_setdirty:
984263bc
MD
2014 *
2015 * Sets the dirty range for a buffer based on the status of the dirty
2016 * bits in the pages comprising the buffer.
2017 *
2018 * The range is limited to the size of the buffer.
2019 *
2020 * This routine is primarily used by NFS, but is generalized for the
2021 * B_VMIO case.
2022 */
2023static void
2024vfs_setdirty(struct buf *bp)
2025{
2026 int i;
2027 vm_object_t object;
2028
2029 /*
2030 * Degenerate case - empty buffer
2031 */
2032
2033 if (bp->b_bufsize == 0)
2034 return;
2035
2036 /*
2037 * We qualify the scan for modified pages on whether the
2038 * object has been flushed yet. The OBJ_WRITEABLE flag
2039 * is not cleared simply by protecting pages off.
2040 */
2041
2042 if ((bp->b_flags & B_VMIO) == 0)
2043 return;
2044
54f51aeb 2045 object = bp->b_xio.xio_pages[0]->object;
984263bc
MD
2046
2047 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
6ea70f76 2048 kprintf("Warning: object %p writeable but not mightbedirty\n", object);
984263bc 2049 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
6ea70f76 2050 kprintf("Warning: object %p mightbedirty but not writeable\n", object);
984263bc
MD
2051
2052 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
2053 vm_offset_t boffset;
2054 vm_offset_t eoffset;
2055
2056 /*
2057 * test the pages to see if they have been modified directly
2058 * by users through the VM system.
2059 */
54f51aeb
HP
2060 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2061 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO);
2062 vm_page_test_dirty(bp->b_xio.xio_pages[i]);
984263bc
MD
2063 }
2064
2065 /*
2066 * Calculate the encompassing dirty range, boffset and eoffset,
2067 * (eoffset - boffset) bytes.
2068 */
2069
54f51aeb
HP
2070 for (i = 0; i < bp->b_xio.xio_npages; i++) {
2071 if (bp->b_xio.xio_pages[i]->dirty)
984263bc
MD
2072 break;
2073 }
81b5c339 2074 boffset = (i << PAGE_SHIFT) - (bp->b_loffset & PAGE_MASK);
984263bc 2075
54f51aeb
HP
2076 for (i = bp->b_xio.xio_npages - 1; i >= 0; --i) {
2077 if (bp->b_xio.xio_pages[i]->dirty) {
984263bc
MD
2078 break;
2079 }
2080 }
81b5c339 2081 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_loffset & PAGE_MASK);
984263bc
MD
2082
2083 /*
2084 * Fit it to the buffer.
2085 */
2086
2087 if (eoffset > bp->b_bcount)
2088 eoffset = bp->b_bcount;
2089
2090 /*
2091 * If we have a good dirty range, merge with the existing
2092 * dirty range.
2093 */
2094
2095 if (boffset < eoffset) {
2096 if (bp->b_dirtyoff > boffset)
2097 bp->b_dirtyoff = boffset;
2098 if (bp->b_dirtyend < eoffset)
2099 bp->b_dirtyend = eoffset;
2100 }
2101 }
2102}
2103
1f1ea522
MD
2104/*
2105 * findblk:
2106 *
2107 * Locate and return the specified buffer, or NULL if the buffer does
2108 * not exist. Do not attempt to lock the buffer or manipulate it in
2109 * any way. The caller must validate that the correct buffer has been
2110 * obtain after locking it.
2111 */
2112struct buf *
54078292 2113findblk(struct vnode *vp, off_t loffset)
1f1ea522
MD
2114{
2115 struct buf *bp;
2116
2117 crit_enter();
54078292 2118 bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset);
1f1ea522
MD
2119 crit_exit();
2120 return(bp);
2121}
2122
984263bc 2123/*
3f779080 2124 * getblk:
984263bc
MD
2125 *
2126 * Get a block given a specified block and offset into a file/device.
10f3fee5
MD
2127 * B_INVAL may or may not be set on return. The caller should clear
2128 * B_INVAL prior to initiating a READ.
984263bc 2129 *
77bb9400
MD
2130 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE
2131 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ,
2132 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer
2133 * without doing any of those things the system will likely believe
2134 * the buffer to be valid (especially if it is not B_VMIO), and the
2135 * next getblk() will return the buffer with B_CACHE set.
2136 *
984263bc
MD
2137 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
2138 * an existing buffer.
2139 *
2140 * For a VMIO buffer, B_CACHE is modified according to the backing VM.
2141 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
2142 * and then cleared based on the backing VM. If the previous buffer is
2143 * non-0-sized but invalid, B_CACHE will be cleared.
2144 *
2145 * If getblk() must create a new buffer, the new buffer is returned with
2146 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
2147 * case it is returned with B_INVAL clear and B_CACHE set based on the
2148 * backing VM.
2149 *
62cfda27 2150 * getblk() also forces a bwrite() for any B_DELWRI buffer whos
984263bc
MD
2151 * B_CACHE bit is clear.
2152 *
2153 * What this means, basically, is that the caller should use B_CACHE to
2154 * determine whether the buffer is fully valid or not and should clear
2155 * B_INVAL prior to issuing a read. If the caller intends to validate
2156 * the buffer by loading its data area with something, the caller needs
2157 * to clear B_INVAL. If the caller does this without issuing an I/O,
2158 * the caller should set B_CACHE ( as an optimization ), else the caller
2159 * should issue the I/O and biodone() will set B_CACHE if the I/O was
2160 * a write attempt or if it was a successfull read. If the caller
2161 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR
2162 * prior to issuing the READ. biodone() will *not* clear B_INVAL.
2163 */
2164struct buf *
54078292 2165getblk(struct vnode *vp, off_t loffset, int size, int slpflag, int slptimeo)
984263bc
MD
2166{
2167 struct buf *bp;
984263bc
MD
2168
2169 if (size > MAXBSIZE)
fc92d4aa 2170 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE);
7540ab49
MD
2171 if (vp->v_object == NULL)
2172 panic("getblk: vnode %p has no object!", vp);
984263bc 2173
e43a034f 2174 crit_enter();
984263bc
MD
2175loop:
2176 /*
2177 * Block if we are low on buffers. Certain processes are allowed
2178 * to completely exhaust the buffer cache.
2179 *
2180 * If this check ever becomes a bottleneck it may be better to
1f1ea522 2181 * move it into the else, when findblk() fails. At the moment
984263bc
MD
2182 * it isn't a problem.
2183 *
2184 * XXX remove, we cannot afford to block anywhere if holding a vnode
2185 * lock in low-memory situation, so take it to the max.
2186 */
2187 if (numfreebuffers == 0) {
2188 if (!curproc)
2189 return NULL;
2190 needsbuffer |= VFS_BIO_NEED_ANY;
377d4740 2191 tsleep(&needsbuffer, slpflag, "newbuf", slptimeo);
984263bc
MD
2192 }
2193
54078292 2194 if ((bp = findblk(vp, loffset))) {
984263bc 2195 /*
a0da602d
MD
2196 * The buffer was found in the cache, but we need to lock it.
2197 * Even with LK_NOWAIT the lockmgr may break our critical
2198 * section, so double-check the validity of the buffer
2199 * once the lock has been obtained.
984263bc 2200 */
984263bc 2201 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
f2770c70
MD
2202 int lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL;
2203 if (slpflag & PCATCH)
2204 lkflags |= LK_PCATCH;
2205 if (BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo) ==
2206 ENOLCK) {
984263bc 2207 goto loop;
f2770c70 2208 }
e43a034f 2209 crit_exit();
f2770c70 2210 return (NULL);
984263bc
MD
2211 }
2212
a0da602d
MD
2213 /*
2214 * Once the buffer has been locked, make sure we didn't race
2215 * a buffer recyclement. Buffers that are no longer hashed
2216 * will have b_vp == NULL, so this takes care of that check
2217 * as well.
2218 */
54078292 2219 if (bp->b_vp != vp || bp->b_loffset != loffset) {
6ea70f76 2220 kprintf("Warning buffer %p (vp %p loffset %lld) was recycled\n", bp, vp, loffset);
a9518ecf 2221 BUF_UNLOCK(bp);
a0da602d
MD
2222 goto loop;
2223 }
2224
4baec531
MD
2225 /*
2226 * All vnode-based buffers must be backed by a VM object.
2227 */
2228 KKASSERT(bp->b_flags & B_VMIO);
10f3fee5 2229 KKASSERT(bp->b_cmd == BUF_CMD_DONE);
4baec531 2230
a0da602d
MD
2231 /*
2232 * Make sure that B_INVAL buffers do not have a cached
2233 * block number translation.
2234 */
54078292 2235 if ((bp->b_flags & B_INVAL) && (bp->b_bio2.bio_offset != NOOFFSET)) {
6ea70f76 2236 kprintf("Warning invalid buffer %p (vp %p loffset %lld) did not have cleared bio_offset cache\n", bp, vp, loffset);
81b5c339 2237 clearbiocache(&bp->b_bio2);
a0da602d
MD
2238 }
2239
984263bc
MD
2240 /*
2241 * The buffer is locked. B_CACHE is cleared if the buffer is
4baec531 2242 * invalid.
984263bc
MD
2243 */
2244 if (bp->b_flags & B_INVAL)
2245 bp->b_flags &= ~B_CACHE;
984263bc
MD
2246 bremfree(bp);
2247
2248 /*
4baec531
MD
2249 * Any size inconsistancy with a dirty buffer or a buffer
2250 * with a softupdates dependancy must be resolved. Resizing
2251 * the buffer in such circumstances can lead to problems.
984263bc 2252 */
4baec531
MD
2253 if (size != bp->b_bcount) {
2254 if (bp->b_flags & B_DELWRI) {
2255 bp->b_flags |= B_NOCACHE;
62cfda27 2256 bwrite(bp);
4baec531
MD
2257 } else if (LIST_FIRST(&bp->b_dep)) {
2258 bp->b_flags |= B_NOCACHE;
62cfda27 2259 bwrite(bp);
4baec531
MD
2260 } else {
2261 bp->b_flags |= B_RELBUF;
2262 brelse(bp);
984263bc 2263 }
4baec531 2264 goto loop;
984263bc 2265 }
4baec531 2266 KKASSERT(size <= bp->b_kvasize);
81b5c339
MD
2267 KASSERT(bp->b_loffset != NOOFFSET,
2268 ("getblk: no buffer offset"));
984263bc
MD
2269
2270 /*
2271 * A buffer with B_DELWRI set and B_CACHE clear must
2272 * be committed before we can return the buffer in
2273 * order to prevent the caller from issuing a read
2274 * ( due to B_CACHE not being set ) and overwriting
2275 * it.
2276 *
2277 * Most callers, including NFS and FFS, need this to
2278 * operate properly either because they assume they
2279 * can issue a read if B_CACHE is not set, or because
2280 * ( for example ) an uncached B_DELWRI might loop due
2281 * to softupdates re-dirtying the buffer. In the latter
2282 * case, B_CACHE is set after the first write completes,
2283 * preventing further loops.
2284 *
2285 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
2286 * above while extending the buffer, we cannot allow the
2287 * buffer to remain with B_CACHE set after the write
2288 * completes or it will represent a corrupt state. To
2289 * deal with this we set B_NOCACHE to scrap the buffer
2290 * after the write.
2291 *
2292 * We might be able to do something fancy, like setting
2293 * B_CACHE in bwrite() except if B_DELWRI is already set,
2294 * so the below call doesn't set B_CACHE, but that gets real
2295 * confusing. This is much easier.
2296 */
2297
2298 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
2299 bp->b_flags |= B_NOCACHE;
62cfda27 2300 bwrite(bp);
984263bc
MD
2301 goto loop;
2302 }
e43a034f 2303 crit_exit();
984263bc
MD
2304 } else {
2305 /*
2306 * Buffer is not in-core, create new buffer. The buffer
2307 * returned by getnewbuf() is locked. Note that the returned
2308 * buffer is also considered valid (not marked B_INVAL).
21ab32bd
MD
2309 *
2310 * Calculating the offset for the I/O requires figuring out
2311 * the block size. We use DEV_BSIZE for VBLK or VCHR and
2312 * the mount's f_iosize otherwise. If the vnode does not
2313 * have an associated mount we assume that the passed size is
2314 * the block size.
2315 *
2316 * Note that vn_isdisk() cannot be used here since it may
2317 * return a failure for numerous reasons. Note that the
2318 * buffer size may be larger then the block size (the caller
2319 * will use block numbers with the proper multiple). Beware
2320 * of using any v_* fields which are part of unions. In
2321 * particular, in DragonFly the mount point overloading
1d505369
MD
2322 * mechanism uses the namecache only and the underlying
2323 * directory vnode is not a special case.
984263bc 2324 */
7540ab49 2325 int bsize, maxsize;
984263bc 2326
21ab32bd 2327 if (vp->v_type == VBLK || vp->v_type == VCHR)
984263bc 2328 bsize = DEV_BSIZE;
984263bc
MD
2329 else if (vp->v_mount)
2330 bsize = vp->v_mount->mnt_stat.f_iosize;
2331 else
2332 bsize = size;
2333
7540ab49 2334 maxsize = size + (loffset & PAGE_MASK);
984263bc
MD
2335 maxsize = imax(maxsize, bsize);
2336
2337 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) {
2338 if (slpflag || slptimeo) {
e43a034f 2339 crit_exit();
984263bc
MD
2340 return NULL;
2341 }
2342 goto loop;
2343 }
2344
2345 /*
2346 * This code is used to make sure that a buffer is not
2347 * created while the getnewbuf routine is blocked.
2348 * This can be a problem whether the vnode is locked or not.
2349 * If the buffer is created out from under us, we have to
179024a5 2350 * throw away the one we just created. There is no window
e43a034f
MD
2351 * race because we are safely running in a critical section
2352 * from the point of the duplicate buffer creation through
2353 * to here, and we've locked the buffer.
984263bc 2354 */
54078292 2355 if (findblk(vp, loffset)) {
984263bc
MD
2356 bp->b_flags |= B_INVAL;
2357 brelse(bp);
2358 goto loop;
2359 }
2360
2361 /*
2362 * Insert the buffer into the hash, so that it can
1f1ea522
MD
2363 * be found by findblk().
2364 *
2365 * Make sure the translation layer has been cleared.
984263bc 2366 */
54078292
MD
2367 bp->b_loffset = loffset;
2368 bp->b_bio2.bio_offset = NOOFFSET;
1f1ea522 2369 /* bp->b_bio2.bio_next = NULL; */
984263bc
MD
2370
2371 bgetvp(vp, bp);
984263bc
MD
2372
2373 /*
4baec531 2374 * All vnode-based buffers must be backed by a VM object.
984263bc 2375 */
4baec531
MD
2376 KKASSERT(vp->v_object != NULL);
2377 bp->b_flags |= B_VMIO;
10f3fee5 2378 KKASSERT(bp->b_cmd == BUF_CMD_DONE);
984263bc
MD
2379
2380 allocbuf(bp, size);
2381
e43a034f 2382 crit_exit();
984263bc
MD
2383 }
2384 return (bp);
2385}
2386
2387/*
3f779080
HP
2388 * geteblk:
2389 *
2390 * Get an empty, disassociated buffer of given size. The buffer is
2391 * initially set to B_INVAL.
06ecca5a 2392 *
3f779080
HP
2393 * critical section protection is not required for the allocbuf()
2394 * call because races are impossible here.
984263bc
MD
2395 */
2396struct buf *
2397geteblk(int size)
2398{
2399 struct buf *bp;
984263bc
MD
2400 int maxsize;
2401
2402 maxsize = (size + BKVAMASK) & ~BKVAMASK;
2403
e43a034f
MD
2404 crit_enter();
2405 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
2406 ;
2407 crit_exit();
984263bc
MD
2408 allocbuf(bp, size);
2409 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
2410 return (bp);
2411}
2412
2413
2414/*
3f779080 2415 * allocbuf:
984263bc 2416 *
3f779080
HP
2417 * This code constitutes the buffer memory from either anonymous system
2418 * memory (in the case of non-VMIO operations) or from an associated
2419 * VM object (in the case of VMIO operations). This code is able to
2420 * resize a buffer up or down.
984263bc 2421 *
3f779080
HP
2422 * Note that this code is tricky, and has many complications to resolve
2423 * deadlock or inconsistant data situations. Tread lightly!!!
2424 * There are B_CACHE and B_DELWRI interactions that must be dealt with by
2425 * the caller. Calling this code willy nilly can result in the loss of data.
06ecca5a 2426 *
3f779080
HP
2427 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
2428 * B_CACHE for the non-VMIO case.
2429 *
2430 * This routine does not need to be called from a critical section but you
2431 * must own the buffer.
984263bc 2432 */
984263bc
MD
2433int
2434allocbuf(struct buf *bp, int size)
2435{
2436 int newbsize, mbsize;
2437 int i;
2438
2439 if (BUF_REFCNT(bp) == 0)
2440 panic("allocbuf: buffer not busy");
2441
2442 if (bp->b_kvasize < size)
2443 panic("allocbuf: buffer too small");
2444
2445 if ((bp->b_flags & B_VMIO) == 0) {
2446 caddr_t origbuf;
2447 int origbufsize;
2448 /*
2449 * Just get anonymous memory from the kernel. Don't
2450 * mess with B_CACHE.
2451 */
2452 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
984263bc
MD
2453 if (bp->b_flags & B_MALLOC)
2454 newbsize = mbsize;
2455 else
984263bc
MD
2456 newbsize = round_page(size);
2457
2458 if (newbsize < bp->b_bufsize) {
984263bc 2459 /*
312dcd01 2460 * Malloced buffers are not shrunk
984263bc
MD
2461 */
2462 if (bp->b_flags & B_MALLOC) {
2463 if (newbsize) {
2464 bp->b_bcount = size;
2465 } else {
efda3bd0 2466 kfree(bp->b_data, M_BIOBUF);
984263bc
MD
2467 if (bp->b_bufsize) {
2468 bufmallocspace -= bp->b_bufsize;
2469 bufspacewakeup();
2470 bp->b_bufsize = 0;
2471 }
2472 bp->b_data = bp->b_kvabase;
2473 bp->b_bcount = 0;
2474 bp->b_flags &= ~B_MALLOC;
2475 }
2476 return 1;
2477 }
984263bc
MD
2478 vm_hold_free_pages(
2479 bp,
2480 (vm_offset_t) bp->b_data + newbsize,
2481 (vm_offset_t) bp->b_data + bp->b_bufsize);
2482 } else if (newbsize > bp->b_bufsize) {
984263bc
MD
2483 /*
2484 * We only use malloced memory on the first allocation.
2485 * and revert to page-allocated memory when the buffer
2486 * grows.
2487 */
4baec531 2488 if ((bufmallocspace < maxbufmallocspace) &&
984263bc
MD
2489 (bp->b_bufsize == 0) &&
2490 (mbsize <= PAGE_SIZE/2)) {
2491
efda3bd0 2492 bp->b_data = kmalloc(mbsize, M_BIOBUF, M_WAITOK);
984263bc
MD
2493 bp->b_bufsize = mbsize;
2494 bp->b_bcount = size;
2495 bp->b_flags |= B_MALLOC;
2496 bufmallocspace += mbsize;
2497 return 1;
2498 }
984263bc
MD
2499 origbuf = NULL;
2500 origbufsize = 0;
984263bc 2501 /*
4baec531
MD
2502 * If the buffer is growing on its other-than-first
2503 * allocation, then we revert to the page-allocation
2504 * scheme.
984263bc
MD
2505 */
2506 if (bp->b_flags & B_MALLOC) {
2507 origbuf = bp->b_data;
2508 origbufsize = bp->b_bufsize;
2509 bp->b_data = bp->b_kvabase;
2510 if (bp->b_bufsize) {
2511 bufmallocspace -= bp->b_bufsize;
2512 bufspacewakeup();
2513 bp->b_bufsize = 0;
2514 }
2515 bp->b_flags &= ~B_MALLOC;
2516 newbsize = round_page(newbsize);
2517 }
984263bc
MD
2518 vm_hold_load_pages(
2519 bp,
2520 (vm_offset_t) bp->b_data + bp->b_bufsize,
2521 (vm_offset_t) bp->b_data + newbsize);
984263bc
MD
2522 if (origbuf) {
2523 bcopy(origbuf, bp->b_data, origbufsize);
efda3bd0 2524 kfree(origbuf, M_BIOBUF);
984263bc 2525 }
984263bc
MD
2526 }
2527 } else {
2528 vm_page_t m;
2529 int desiredpages;
2530
2531 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
4baec531
MD
2532 desiredpages = ((int)(bp->b_loffset & PAGE_MASK) +
2533 newbsize + PAGE_MASK) >> PAGE_SHIFT;
2534 KKASSERT(desiredpages <= XIO_INTERNAL_PAGES);
984263bc 2535
984263bc
MD
2536 if (bp->b_flags & B_MALLOC)
2537 panic("allocbuf: VMIO buffer can't be malloced");
984263bc
MD
2538 /*
2539 * Set B_CACHE initially if buffer is 0 length or will become
2540 * 0-length.
2541 */
2542 if (size == 0 || bp->b_bufsize == 0)
2543 bp->b_flags |= B_CACHE;
2544
2545 if (newbsize < bp->b_bufsize) {
2546 /*
2547 * DEV_BSIZE aligned new buffer size is less then the
2548 * DEV_BSIZE aligned existing buffer size. Figure out
2549 * if we have to remove any pages.
2550 */
54f51aeb
HP
2551 if (desiredpages < bp->b_xio.xio_npages) {
2552 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) {
984263bc
MD
2553 /*
2554 * the page is not freed here -- it
2555 * is the responsibility of
2556 * vnode_pager_setsize
2557 */
54f51aeb 2558 m = bp->b_xio.xio_pages[i];
984263bc
MD
2559 KASSERT(m != bogus_page,
2560 ("allocbuf: bogus page found"));
2561 while (vm_page_sleep_busy(m, TRUE, "biodep"))
2562 ;
2563
54f51aeb 2564 bp->b_xio.xio_pages[i] = NULL;
984263bc
MD
2565 vm_page_unwire(m, 0);
2566 }
2567 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
54f51aeb
HP
2568 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages));
2569 bp->b_xio.xio_npages = desiredpages;
984263bc
MD
2570 }
2571 } else if (size > bp->b_bcount) {
2572 /*
2573 * We are growing the buffer, possibly in a
2574 * byte-granular fashion.
2575 */
2576 struct vnode *vp;
2577 vm_object_t obj;
2578 vm_offset_t toff;
2579 vm_offset_t tinc;
2580
2581 /*
2582 * Step 1, bring in the VM pages from the object,
2583 * allocating them if necessary. We must clear
2584 * B_CACHE if these pages are not valid for the
2585 * range covered by the buffer.
06ecca5a 2586 *
e43a034f
MD
2587 * critical section protection is required to protect
2588 * against interrupts unbusying and freeing pages
2589 * between our vm_page_lookup() and our
2590 * busycheck/wiring call.
984263bc 2591 */
984263bc 2592 vp = bp->b_vp;
7540ab49 2593 obj = vp->v_object;
984263bc 2594
654a39f0 2595 crit_enter();
54f51aeb 2596 while (bp->b_xio.xio_npages < desiredpages) {
984263bc
MD
2597 vm_page_t m;
2598 vm_pindex_t pi;
2599
81b5c339 2600 pi = OFF_TO_IDX(bp->b_loffset) + bp->b_xio.xio_npages;
984263bc
MD
2601 if ((m = vm_page_lookup(obj, pi)) == NULL) {
2602 /*
2603 * note: must allocate system pages
2604 * since blocking here could intefere
2605 * with paging I/O, no matter which
2606 * process we are.
2607 */
dc1fd4b3 2608 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM);
984263bc 2609 if (m == NULL) {
659c6a07 2610 vm_wait();
54f51aeb
HP
2611 vm_pageout_deficit += desiredpages -
2612 bp->b_xio.xio_npages;
984263bc
MD
2613 } else {
2614 vm_page_wire(m);
2615 vm_page_wakeup(m);
2616 bp->b_flags &= ~B_CACHE;
54f51aeb
HP
2617 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
2618 ++bp->b_xio.xio_npages;
984263bc
MD
2619 }
2620 continue;
2621 }
2622
2623 /*
2624 * We found a page. If we have to sleep on it,
2625 * retry because it might have gotten freed out
2626 * from under us.
2627 *
2628 * We can only test PG_BUSY here. Blocking on
2629 * m->busy might lead to a deadlock:
2630 *
2631 * vm_fault->getpages->cluster_read->allocbuf
2632 *
2633 */
2634
2635 if (vm_page_sleep_busy(m, FALSE, "pgtblk"))
2636 continue;
2637
2638 /*
2639 * We have a good page. Should we wakeup the
2640 * page daemon?
2641 */
bc6dffab 2642 if ((curthread != pagethread) &&
984263bc 2643 ((m->queue - m->pc) == PQ_CACHE) &&
12e4aaff
MD
2644 ((vmstats.v_free_count + vmstats.v_cache_count) <
2645 (vmstats.v_free_min + vmstats.v_cache_min))) {
984263bc
MD
2646 pagedaemon_wakeup();
2647 }
2648 vm_page_flag_clear(m, PG_ZERO);
2649 vm_page_wire(m);
54f51aeb
HP
2650 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
2651 ++bp->b_xio.xio_npages;
984263bc 2652 }
654a39f0 2653 crit_exit();
984263bc
MD
2654
2655 /*
2656 * Step 2. We've loaded the pages into the buffer,
2657 * we have to figure out if we can still have B_CACHE
2658 * set. Note that B_CACHE is set according to the
3f779080 2659 * byte-granular range ( bcount and size ), not the
984263bc
MD
2660 * aligned range ( newbsize ).
2661 *
2662 * The VM test is against m->valid, which is DEV_BSIZE
2663 * aligned. Needless to say, the validity of the data
2664 * needs to also be DEV_BSIZE aligned. Note that this
2665 * fails with NFS if the server or some other client
2666 * extends the file's EOF. If our buffer is resized,
2667 * B_CACHE may remain set! XXX
2668 */
2669
2670 toff = bp->b_bcount;
81b5c339 2671 tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK);
984263bc
MD
2672
2673 while ((bp->b_flags & B_CACHE) && toff < size) {
2674 vm_pindex_t pi;
2675
2676 if (tinc > (size - toff))
2677 tinc = size - toff;
2678
81b5c339 2679 pi = ((bp->b_loffset & PAGE_MASK) + toff) >>
984263bc
MD
2680 PAGE_SHIFT;
2681
2682 vfs_buf_test_cache(
2683 bp,
81b5c339 2684 bp->b_loffset,
984263bc
MD
2685 toff,
2686 tinc,
54f51aeb 2687 bp->b_xio.xio_pages[pi]
984263bc
MD
2688 );
2689 toff += tinc;
2690 tinc = PAGE_SIZE;
2691 }
2692
2693 /*
2694 * Step 3, fixup the KVM pmap. Remember that
81b5c339
MD
2695 * bp->b_data is relative to bp->b_loffset, but
2696 * bp->b_loffset may be offset into the first page.
984263bc
MD
2697 */
2698
2699 bp->b_data = (caddr_t)
2700 trunc_page((vm_offset_t)bp->b_data);
2701 pmap_qenter(
2702 (vm_offset_t)bp->b_data,
54f51aeb
HP
2703 bp->b_xio.xio_pages,
2704 bp->b_xio.xio_npages
984263bc
MD
2705 );
2706 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
81b5c339 2707 (vm_offset_t)(bp->b_loffset & PAGE_MASK));
984263bc
MD
2708 }
2709 }
2710 if (newbsize < bp->b_bufsize)
2711 bufspacewakeup();
2712 bp->b_bufsize = newbsize; /* actual buffer allocation */
2713 bp->b_bcount = size; /* requested buffer size */
2714 return 1;
2715}
2716
2717/*
3f779080 2718 * biowait:
984263bc
MD
2719 *
2720 * Wait for buffer I/O completion, returning error status. The buffer
10f3fee5
MD
2721 * is left locked on return. B_EINTR is converted into an EINTR error
2722 * and cleared.
2723 *
2724 * NOTE! The original b_cmd is lost on return, since b_cmd will be
2725 * set to BUF_CMD_DONE.
984263bc
MD
2726 */
2727int
c8e4131d 2728biowait(struct buf *bp)
984263bc 2729{
e43a034f 2730 crit_enter();
10f3fee5
MD
2731 while (bp->b_cmd != BUF_CMD_DONE) {
2732 if (bp->b_cmd == BUF_CMD_READ)
377d4740 2733 tsleep(bp, 0, "biord", 0);
984263bc 2734 else
377d4740 2735 tsleep(bp, 0, "biowr", 0);
984263bc 2736 }
e43a034f 2737 crit_exit();
984263bc
MD
2738 if (bp->b_flags & B_EINTR) {
2739 bp->b_flags &= ~B_EINTR;
2740 return (EINTR);
2741 }
2742 if (bp->b_flags & B_ERROR) {
2743 return (bp->b_error ? bp->b_error : EIO);
2744 } else {
2745 return (0);
2746 }
2747}
2748
81b5c339
MD
2749/*
2750 * This associates a tracking count with an I/O. vn_strategy() and
2751 * dev_dstrategy() do this automatically but there are a few cases
2752 * where a vnode or device layer is bypassed when a block translation
2753 * is cached. In such cases bio_start_transaction() may be called on
2754 * the bypassed layers so the system gets an I/O in progress indication
2755 * for those higher layers.
2756 */
2757void
2758bio_start_transaction(struct bio *bio, struct bio_track *track)
2759{
2760 bio->bio_track = track;
2761 atomic_add_int(&track->bk_active, 1);
2762}
2763
2764/*
2765 * Initiate I/O on a vnode.
2766 */
2767void
2768vn_strategy(struct vnode *vp, struct bio *bio)
2769{
2770 struct bio_track *track;
2771
10f3fee5
MD
2772 KKASSERT(bio->bio_buf->b_cmd != BUF_CMD_DONE);
2773 if (bio->bio_buf->b_cmd == BUF_CMD_READ)
81b5c339
MD
2774 track = &vp->v_track_read;
2775 else
2776 track = &vp->v_track_write;
2777 bio->bio_track = track;
2778 atomic_add_int(&track->bk_active, 1);
2779 vop_strategy(*vp->v_ops, vp, bio);
2780}
2781
2782
984263bc 2783/*
3f779080 2784 * biodone:
984263bc
MD
2785 *
2786 * Finish I/O on a buffer, optionally calling a completion function.
2787 * This is usually called from an interrupt so process blocking is
2788 * not allowed.
2789 *
2790 * biodone is also responsible for setting B_CACHE in a B_VMIO bp.
2791 * In a non-VMIO bp, B_CACHE will be set on the next getblk()
2792 * assuming B_INVAL is clear.
2793 *
2794 * For the VMIO case, we set B_CACHE if the op was a read and no
2795 * read error occured, or if the op was a write. B_CACHE is never
2796 * set if the buffer is invalid or otherwise uncacheable.
2797 *
2798 * biodone does not mess with B_INVAL, allowing the I/O routine or the
2799 * initiator to leave B_INVAL set to brelse the buffer out of existance
2800 * in the biodone routine.
2801 */
2802void
81b5c339 2803biodone(struct bio *bio)
984263bc 2804{
81b5c339 2805 struct buf *bp = bio->bio_buf;
10f3fee5 2806 buf_cmd_t cmd;
984263bc 2807
e43a034f 2808 crit_enter();
984263bc 2809
81b5c339
MD
2810 KASSERT(BUF_REFCNTNB(bp) > 0,
2811 ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp)));
10f3fee5
MD
2812 KASSERT(bp->b_cmd != BUF_CMD_DONE,
2813 ("biodone: bp %p already done!", bp));
984263bc 2814
984263bc
MD
2815 runningbufwakeup(bp);
2816
81b5c339 2817 /*
10f3fee5 2818 * Run up the chain of BIO's. Leave b_cmd intact for the duration.
81b5c339
MD
2819 */
2820 while (bio) {
2821 biodone_t *done_func;
2822 struct bio_track *track;
984263bc 2823
81b5c339
MD
2824 /*
2825 * BIO tracking. Most but not all BIOs are tracked.
2826 */
2827 if ((track = bio->bio_track) != NULL) {
2828 atomic_subtract_int(&track->bk_active, 1);
2829 if (track->bk_active < 0) {
2830 panic("biodone: bad active count bio %p\n",
2831 bio);
2832 }
2833 if (track->bk_waitflag) {
2834 track->bk_waitflag = 0;
2835 wakeup(track);
2836 }
2837 bio->bio_track = NULL;
2838 }
2839
2840 /*
2841 * A bio_done function terminates the loop. The function
2842 * will be responsible for any further chaining and/or
2843 * buffer management.
10f3fee5
MD
2844 *
2845 * WARNING! The done function can deallocate the buffer!
81b5c339
MD
2846 */
2847 if ((done_func = bio->bio_done) != NULL) {
2848 bio->bio_done = NULL;
2849 done_func(bio);
2850 crit_exit();
2851 return;
2852 }
2853 bio = bio->bio_prev;
984263bc
MD
2854 }
2855
10f3fee5
MD
2856 cmd = bp->b_cmd;
2857 bp->b_cmd = BUF_CMD_DONE;
2858
81b5c339 2859 /*
10f3fee5 2860 * Only reads and writes are processed past this point.
81b5c339 2861 */
10f3fee5 2862 if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) {
81b5c339 2863 brelse(bp);
e43a034f 2864 crit_exit();
984263bc
MD
2865 return;
2866 }
81b5c339 2867
69f8c926
MD
2868 /*
2869 * Warning: softupdates may re-dirty the buffer.
2870 */
984263bc
MD
2871 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete)
2872 (*bioops.io_complete)(bp);
2873
2874 if (bp->b_flags & B_VMIO) {
2875 int i;
2876 vm_ooffset_t foff;
2877 vm_page_t m;
2878 vm_object_t obj;
2879 int iosize;
2880 struct vnode *vp = bp->b_vp;
2881
7540ab49 2882 obj = vp->v_object;
984263bc
MD
2883
2884#if defined(VFS_BIO_DEBUG)
3c37c940 2885 if (vp->v_auxrefs == 0)
8a6722ed 2886 panic("biodone: zero vnode hold count");
7540ab49 2887 if ((vp->v_flag & VOBJBUF) == 0)
984263bc 2888 panic("biodone: vnode is not setup for merged cache");
984263bc
MD
2889#endif
2890
81b5c339
MD
2891 foff = bp->b_loffset;
2892 KASSERT(foff != NOOFFSET, ("biodone: no buffer offset"));
7540ab49 2893 KASSERT(obj != NULL, ("biodone: missing VM object"));
984263bc 2894
984263bc 2895#if defined(VFS_BIO_DEBUG)
54f51aeb 2896 if (obj->paging_in_progress < bp->b_xio.xio_npages) {
6ea70f76 2897 kprintf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n",
54f51aeb 2898 obj->paging_in_progress, bp->b_xio.xio_npages);
984263bc
MD
2899 }
2900#endif
2901
2902 /*
2903 * Set B_CACHE if the op was a normal read and no error
2904 * occured. B_CACHE is set for writes in the b*write()
2905 * routines.
2906 */
2907 iosize = bp->b_bcount - bp->b_resid;
10f3fee5 2908 if (cmd == BUF_CMD_READ && (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) {
984263bc
MD
2909 bp->b_flags |= B_CACHE;
2910 }
2911
54f51aeb 2912 for (i = 0; i < bp->b_xio.xio_npages; i++) {
984263bc
MD
2913 int bogusflag = 0;
2914 int resid;
2915
2916 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
2917 if (resid > iosize)
2918 resid = iosize;
2919
2920 /*
06ecca5a
MD
2921 * cleanup bogus pages, restoring the originals. Since
2922 * the originals should still be wired, we don't have
2923 * to worry about interrupt/freeing races destroying
2924 * the VM object association.
984263bc 2925 */
54f51aeb 2926 m = bp->b_xio.xio_pages[i];
984263bc
MD
2927 if (m == bogus_page) {
2928 bogusflag = 1;
2929 m = vm_page_lookup(obj, OFF_TO_IDX(foff));
2930 if (m == NULL)
2931 panic("biodone: page disappeared");
54f51aeb
HP
2932 bp->b_xio.xio_pages[i] = m;
2933 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
2934 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
984263bc
MD
2935 }
2936#if defined(VFS_BIO_DEBUG)
2937 if (OFF_TO_IDX(foff) != m->pindex) {
6ea70f76 2938 kprintf(
984263bc
MD
2939"biodone: foff(%lu)/m->pindex(%d) mismatch\n",
2940 (unsigned long)foff, m->pindex);
2941 }
2942#endif
2943
2944 /*
2945 * In the write case, the valid and clean bits are
2946 * already changed correctly ( see bdwrite() ), so we
2947 * only need to do this here in the read case.
2948 */
10f3fee5 2949 if (cmd == BUF_CMD_READ && !bogusflag && resid > 0) {
984263bc
MD
2950 vfs_page_set_valid(bp, foff, i, m);
2951 }
2952 vm_page_flag_clear(m, PG_ZERO);
2953
2954 /*
2955 * when debugging new filesystems or buffer I/O methods, this
2956 * is the most common error that pops up. if you see this, you
2957 * have not set the page busy flag correctly!!!
2958 */
2959 if (m->busy == 0) {
6ea70f76 2960 kprintf("biodone: page busy < 0, "
984263bc
MD
2961 "pindex: %d, foff: 0x(%x,%x), "
2962 "resid: %d, index: %d\n",
2963 (int) m->pindex, (int)(foff >> 32),
2964 (int) foff & 0xffffffff, resid, i);
2965 if (!vn_isdisk(vp, NULL))
6ea70f76 2966 kprintf(" iosize: %ld, loffset: %lld, flags: 0x%08x, npages: %d\n",
984263bc 2967 bp->b_vp->v_mount->mnt_stat.f_iosize,
54078292 2968 bp->b_loffset,
54f51aeb 2969 bp->b_flags, bp->b_xio.xio_npages);
984263bc 2970 else
6ea70f76 2971 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n",
54078292 2972 bp->b_loffset,
54f51aeb 2973 bp->b_flags, bp->b_xio.xio_npages);
6ea70f76 2974 kprintf(" valid: 0x%x, dirty: 0x%x, wired: %d\n",
984263bc 2975 m->valid, m->dirty, m->wire_count);
fc92d4aa 2976 panic("biodone: page busy < 0");
984263bc
MD
2977 }
2978 vm_page_io_finish(m);
2979 vm_object_pip_subtract(obj, 1);
2980 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
2981 iosize -= resid;
2982 }
2983 if (obj)
2984 vm_object_pip_wakeupn(obj, 0);
2985 }
2986
2987 /*
2988 * For asynchronous completions, release the buffer now. The brelse
2989 * will do a wakeup there if necessary - so no need to do a wakeup
2990 * here in the async case. The sync case always needs to do a wakeup.
2991 */
2992
2993 if (bp->b_flags & B_ASYNC) {
2994 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0)
2995 brelse(bp);
2996 else
2997 bqrelse(bp);
2998 } else {
2999 wakeup(bp);
3000 }
e43a034f 3001 crit_exit();
984263bc
MD
3002}
3003
3004/*
3f779080
HP
3005 * vfs_unbusy_pages:
3006 *
3007 * This routine is called in lieu of iodone in the case of
3008 * incomplete I/O. This keeps the busy status for pages
3009 * consistant.
984263bc
MD
3010 */
3011void
493c516a 3012vfs_unbusy_pages(struct buf *bp)
984263bc
MD
3013{
3014 int i;
3015
3016 runningbufwakeup(bp);
3017 if (bp->b_flags & B_VMIO) {
3018 struct vnode *vp = bp->b_vp;
3019 vm_object_t obj;
3020
7540ab49 3021 obj = vp->v_object;
984263bc 3022
54f51aeb
HP
3023 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3024 vm_page_t m = bp->b_xio.xio_pages[i];
984263bc 3025
06ecca5a
MD
3026 /*
3027 * When restoring bogus changes the original pages
3028 * should still be wired, so we are in no danger of
3029 * losing the object association and do not need
e43a034f 3030 * critical section protection particularly.
06ecca5a 3031 */
984263bc 3032 if (m == bogus_page) {
81b5c339 3033 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i);
984263bc 3034 if (!m) {
fc92d4aa 3035 panic("vfs_unbusy_pages: page missing");
984263bc 3036 }
54f51aeb
HP
3037 bp->b_xio.xio_pages[i] = m;
3038 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3039 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
984263bc
MD
3040 }
3041 vm_object_pip_subtract(obj, 1);
3042 vm_page_flag_clear(m, PG_ZERO);
3043 vm_page_io_finish(m);
3044 }
3045 vm_object_pip_wakeupn(obj, 0);
3046 }
3047}
3048
3049/*
3050 * vfs_page_set_valid:
3051 *
3052 * Set the valid bits in a page based on the supplied offset. The
3053 * range is restricted to the buffer's size.
3054 *
3055 * This routine is typically called after a read completes.
3056 */
3057static void
3058vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
3059{
3060 vm_ooffset_t soff, eoff;
3061
3062 /*
3063 * Start and end offsets in buffer. eoff - soff may not cross a
3064 * page boundry or cross the end of the buffer. The end of the
3065 * buffer, in this case, is our file EOF, not the allocation size
3066 * of the buffer.
3067 */
3068 soff = off;
3069 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
81b5c339
MD
3070 if (eoff > bp->b_loffset + bp->b_bcount)
3071 eoff = bp->b_loffset + bp->b_bcount;
984263bc
MD
3072
3073 /*
3074 * Set valid range. This is typically the entire buffer and thus the
3075 * entire page.
3076 */
3077 if (eoff > soff) {
3078 vm_page_set_validclean(
3079 m,
3080 (vm_offset_t) (soff & PAGE_MASK),
3081 (vm_offset_t) (eoff - soff)
3082 );
3083 }
3084}
3085
3086/*
3f779080
HP
3087 * vfs_busy_pages:
3088 *
3089 * This routine is called before a device strategy routine.
3090 * It is used to tell the VM system that paging I/O is in
3091 * progress, and treat the pages associated with the buffer
3092 * almost as being PG_BUSY. Also the object 'paging_in_progress'
3093 * flag is handled to make sure that the object doesn't become
3094 * inconsistant.
3095 *
3096 * Since I/O has not been initiated yet, certain buffer flags
3097 * such as B_ERROR or B_INVAL may be in an inconsistant state
3098 * and should be ignored.
984263bc
MD
3099 */
3100void
10f3fee5 3101vfs_busy_pages(struct vnode *vp, struct buf *bp)
984263bc
MD
3102{
3103 int i, bogus;
fde7ac71 3104 struct lwp *lp = curthread->td_lwp;
984263bc 3105
a8f169e2 3106 /*
10f3fee5
MD
3107 * The buffer's I/O command must already be set. If reading,
3108 * B_CACHE must be 0 (double check against callers only doing
3109 * I/O when B_CACHE is 0).
a8f169e2 3110 */
10f3fee5
MD
3111 KKASSERT(bp->b_cmd != BUF_CMD_DONE);
3112 KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0);
a8f169e2 3113
984263bc 3114 if (bp->b_flags & B_VMIO) {
984263bc
MD
3115 vm_object_t obj;
3116 vm_ooffset_t foff;
3117
7540ab49 3118 obj = vp->v_object;
81b5c339
MD
3119 foff = bp->b_loffset;
3120 KASSERT(bp->b_loffset != NOOFFSET,
3121 ("vfs_busy_pages: no buffer offset"));
984263bc
MD
3122 vfs_setdirty(bp);
3123
3124retry:
54f51aeb
HP
3125 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3126 vm_page_t m = bp->b_xio.xio_pages[i];
984263bc
MD
3127 if (vm_page_sleep_busy(m, FALSE, "vbpage"))
3128 goto retry;
3129 }
3130
3131 bogus = 0;
54f51aeb
HP
3132 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3133 vm_page_t m = bp->b_xio.xio_pages[i];
984263bc
MD
3134
3135 vm_page_flag_clear(m, PG_ZERO);
3136 if ((bp->b_flags & B_CLUSTER) == 0) {
3137 vm_object_pip_add(obj, 1);
3138 vm_page_io_start(m);
3139 }
3140
3141 /*
10f3fee5
MD
3142 * When readying a vnode-backed buffer for a write
3143 * we must zero-fill any invalid portions of the
3144 * backing VM pages.
3145 *
3146 * When readying a vnode-backed buffer for a read
3147 * we must replace any dirty pages with a bogus
3148 * page so we do not destroy dirty data when
3149 * filling in gaps. Dirty pages might not
3150 * necessarily be marked dirty yet, so use m->valid
3151 * as a reasonable test.
3152 *
3153 * Bogus page replacement is, uh, bogus. We need
3154 * to find a better way.
984263bc 3155 */
984263bc 3156 vm_page_protect(m, VM_PROT_NONE);
10f3fee5 3157 if (bp->b_cmd == BUF_CMD_WRITE) {
984263bc 3158 vfs_page_set_valid(bp, foff, i, m);
a8f169e2 3159 } else if (m->valid == VM_PAGE_BITS_ALL) {
54f51aeb 3160 bp->b_xio.xio_pages[i] = bogus_page;
984263bc
MD
3161 bogus++;
3162 }
3163 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3164 }
3165 if (bogus)
54f51aeb
HP
3166 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
3167 bp->b_xio.xio_pages, bp->b_xio.xio_npages);
984263bc 3168 }
05edc21a
MD
3169
3170 /*
3171 * This is the easiest place to put the process accounting for the I/O
3172 * for now.
3173 */
fde7ac71 3174 if (lp != NULL) {
10f3fee5 3175 if (bp->b_cmd == BUF_CMD_READ)
fde7ac71 3176 lp->lwp_ru.ru_inblock++;
081e0330 3177 else
fde7ac71 3178 lp->lwp_ru.ru_oublock++;
05edc21a 3179 }
984263bc
MD
3180}
3181
3182/*
3f779080
HP
3183 * vfs_clean_pages:
3184 *
3185 * Tell the VM system that the pages associated with this buffer
3186 * are clean. This is used for delayed writes where the data is
3187 * going to go to disk eventually without additional VM intevention.
984263bc 3188 *
3f779080
HP
3189 * Note that while we only really need to clean through to b_bcount, we
3190 * just go ahead and clean through to b_bufsize.
984263bc
MD
3191 */
3192static void
493c516a 3193vfs_clean_pages(struct buf *bp)
984263bc
MD
3194{
3195 int i;
3196
3197 if (bp->b_flags & B_VMIO) {
3198 vm_ooffset_t foff;
3199
81b5c339
MD
3200 foff = bp->b_loffset;
3201 KASSERT(foff != NOOFFSET, ("vfs_clean_pages: no buffer offset"));
54f51aeb
HP
3202 for (i = 0; i < bp->b_xio.xio_npages; i++) {
3203 vm_page_t m = bp->b_xio.xio_pages[i];
984263bc
MD
3204 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
3205 vm_ooffset_t eoff = noff;
3206
81b5c339
MD
3207 if (eoff > bp->b_loffset + bp->b_bufsize)
3208 eoff = bp->b_loffset + bp->b_bufsize;
984263bc
MD
3209 vfs_page_set_valid(bp, foff, i, m);
3210 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
3211 foff = noff;
3212 }
3213 }
3214}
3215
3216/*
3f779080 3217 * vfs_bio_set_validclean:
984263bc
MD
3218 *
3219 * Set the range within the buffer to valid and clean. The range is
81b5c339
MD
3220 * relative to the beginning of the buffer, b_loffset. Note that
3221 * b_loffset itself may be offset from the beginning of the first page.
984263bc
MD
3222 */
3223
3224void
3225vfs_bio_set_validclean(struct buf *bp, int base, int size)
3226{
3227 if (bp->b_flags & B_VMIO) {
3228 int i;
3229 int n;
3230
3231 /*
3232 * Fixup base to be relative to beginning of first page.
3233 * Set initial n to be the maximum number of bytes in the
3234 * first page that can be validated.
3235 */
3236
81b5c339 3237 base += (bp->b_loffset & PAGE_MASK);
984263bc
MD
3238 n = PAGE_SIZE - (base & PAGE_MASK);
3239
54f51aeb
HP
3240 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_xio.xio_npages; ++i) {
3241 vm_page_t m = bp->b_xio.xio_pages[i];
984263bc
MD
3242
3243 if (n > size)
3244 n = size;
3245
3246 vm_page_set_validclean(m, base & PAGE_MASK, n);
3247 base += n;
3248 size -= n;
3249 n = PAGE_SIZE;
3250 }
3251 }
3252}
3253
3254/*
3f779080 3255 * vfs_bio_clrbuf:
984263bc 3256 *
3f779080 3257 * Clear a buffer. This routine essentially fakes an I/O, so we need
984263bc
MD
3258 * to clear B_ERROR and B_INVAL.
3259 *
3260 * Note that while we only theoretically need to clear through b_bcount,
3261 * we go ahead and clear through b_bufsize.
3262 */
3263
3264void
3265vfs_bio_clrbuf(struct buf *bp)
3266{
3267 int i, mask = 0;
3268 caddr_t sa, ea;
3269 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) {
3270 bp->b_flags &= ~(B_INVAL|B_ERROR);
54f51aeb 3271 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
81b5c339 3272 (bp->b_loffset & PAGE_MASK) == 0) {
984263bc 3273 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
54f51aeb 3274 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) {
984263bc
MD
3275 bp->b_resid = 0;
3276 return;
3277 }
54f51aeb
HP
3278 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) &&
3279 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) {
984263bc 3280 bzero(bp->b_data, bp->b_bufsize);
54f51aeb 3281 bp->b_xio.xio_pages[0]->valid |= mask;
984263bc
MD
3282 bp->b_resid = 0;
3283 return;
3284 }
3285 }
3286 ea = sa = bp->b_data;
54f51aeb 3287 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) {
984263bc
MD
3288 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
3289 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
3290 ea = (caddr_t)(vm_offset_t)ulmin(
3291 (u_long)(vm_offset_t)ea,
3292 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
3293 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
54f51aeb 3294 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask)
984263bc 3295 continue;
54f51aeb
HP
3296 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) {
3297 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) {
984263bc
MD
3298 bzero(sa, ea - sa);
3299 }
3300 } else {
3301 for (; sa < ea; sa += DEV_BSIZE, j++) {
54f51aeb
HP
3302 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) &&
3303 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0)
984263bc
MD
3304 bzero(sa, DEV_BSIZE);
3305 }
3306 }
54f51aeb
HP
3307 bp->b_xio.xio_pages[i]->valid |= mask;
3308 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO);
984263bc
MD
3309 }
3310 bp->b_resid = 0;
3311 } else {
3312 clrbuf(bp);
3313 }
3314}
3315
3316/*
3f779080
HP
3317 * vm_hold_load_pages:
3318 *
3319 * Load pages into the buffer's address space. The pages are
3320 * allocated from the kernel object in order to reduce interference
3321 * with the any VM paging I/O activity. The range of loaded
3322 * pages will be wired.
3323 *
3324 * If a page cannot be allocated, the 'pagedaemon' is woken up to
3325 * retrieve the full range (to - from) of pages.
3326 *
984263bc
MD
3327 */
3328void
493c516a 3329vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
984263bc
MD
3330{
3331 vm_offset_t pg;
3332 vm_page_t p;
3333 int index;
3334
3335 to = round_page(to);
3336 from = round_page(from);
3337 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3338
3339 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
3340
3341tryagain:
3342
3343 /*
3f779080 3344 * Note: must allocate system pages since blocking here
984263bc
MD
3345 * could intefere with paging I/O, no matter which
3346 * process we are.
3347 */
c439ad8f 3348 p = vm_page_alloc(&kernel_object,
e4846942
MD
3349 (pg >> PAGE_SHIFT),
3350 VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM);
984263bc
MD
3351 if (!p) {
3352 vm_pageout_deficit += (to - from) >> PAGE_SHIFT;
659c6a07 3353 vm_wait();
984263bc
MD
3354 goto tryagain;
3355 }
3356 vm_page_wire(p);
3357 p->valid = VM_PAGE_BITS_ALL;
3358 vm_page_flag_clear(p, PG_ZERO);
3359 pmap_kenter(pg, VM_PAGE_TO_PHYS(p));
54f51aeb 3360 bp->b_xio.xio_pages[index] = p;
984263bc
MD
3361 vm_page_wakeup(p);
3362 }
54f51aeb 3363 bp->b_xio.xio_npages = index;
984263bc
MD
3364}
3365
3f779080
HP
3366/*
3367 * vm_hold_free_pages:
3368 *
3369 * Return pages associated with the buffer back to the VM system.
3370 *
3371 * The range of pages underlying the buffer's address space will
3372 * be unmapped and un-wired.
3373 */
984263bc 3374void
493c516a 3375vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
984263bc
MD
3376{
3377 vm_offset_t pg;
3378 vm_page_t p;
3379 int index, newnpages;
3380
3381 from = round_page(from);
3382 to = round_page(to);
3383 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
3384
3385 for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
54f51aeb
HP
3386 p = bp->b_xio.xio_pages[index];
3387 if (p && (index < bp->b_xio.xio_npages)) {
984263bc 3388 if (p->busy) {
6ea70f76 3389 kprintf("vm_hold_free_pages: doffset: %lld, loffset: %lld\n",
54078292 3390 bp->b_bio2.bio_offset, bp->b_loffset);
984263bc 3391 }
54f51aeb 3392 bp->b_xio.xio_pages[index] = NULL;
984263bc
MD
3393 pmap_kremove(pg);
3394 vm_page_busy(p);
3395 vm_page_unwire(p, 0);
3396 vm_page_free(p);
3397 }
3398 }
54f51aeb 3399 bp->b_xio.xio_npages = newnpages;
984263bc
MD
3400}
3401
3402/*
3f779080 3403 * vmapbuf:
984263bc 3404 *
3591bbc6
MD
3405 * Map a user buffer into KVM via a pbuf. On return the buffer's
3406 * b_data, b_bufsize, and b_bcount will be set, and its XIO page array
3407 * initialized.
984263bc
MD
3408 */
3409int
3591bbc6 3410vmapbuf(struct buf *bp, caddr_t udata, int bytes)
984263bc 3411{
3591bbc6 3412 caddr_t addr;
0a3895d4
MD
3413 vm_offset_t va;
3414 vm_page_t m;
3415 int vmprot;
3416 int error;
984263bc
MD
3417 int pidx;
3418 int i;
984263bc 3419
10f3fee5 3420 /*
3591bbc6 3421 * bp had better have a command and it better be a pbuf.
10f3fee5
MD
3422 */
3423 KKASSERT(bp->b_cmd != BUF_CMD_DONE);
3591bbc6 3424 KKASSERT(bp->b_flags & B_PAGING);
10f3fee5 3425
3591bbc6 3426 if (bytes < 0)
984263bc 3427 return (-1);
3591bbc6
MD
3428
3429 /*
3430 * Map the user data into KVM. Mappings have to be page-aligned.
3431 */
3432 addr = (caddr_t)trunc_page((vm_offset_t)udata);
3433 pidx = 0;
3434
3435 vmprot = VM_PROT_READ;
3436 if (bp->b_cmd == BUF_CMD_READ)
3437 vmprot |= VM_PROT_WRITE;
3438
3439 while (addr < udata + bytes) {
984263bc
MD
3440 /*
3441 * Do the vm_fault if needed; do the copy-on-write thing
3442 * when reading stuff off device into memory.
0a3895d4
MD
3443 *
3444 * vm_fault_page*() returns a held VM page.
984263bc 3445 */
0a3895d4
MD
3446 va = (addr >= udata) ? (vm_offset_t)addr : (vm_offset_t)udata;
3447 va = trunc_page(va);
3448
3449 m = vm_fault_page_quick(va, vmprot, &error);
3450 if (m == NULL) {
984263bc 3451 for (i = 0; i < pidx; ++i) {
54f51aeb
HP
3452 vm_page_unhold(bp->b_xio.xio_pages[i]);
3453 bp->b_xio.xio_pages[i] = NULL;
984263bc
MD
3454 }
3455 return(-1);
3456 }
54f51aeb 3457 bp->b_xio.xio_pages[pidx] = m;
3591bbc6
MD
3458 addr += PAGE_SIZE;
3459 ++pidx;
984263bc 3460 }
3591bbc6
MD
3461
3462 /*
3463 * Map the page array and set the buffer fields to point to
3464 * the mapped data buffer.
3465 */
984263bc
MD
3466 if (pidx > btoc(MAXPHYS))
3467 panic("vmapbuf: mapped more than MAXPHYS");
3591bbc6
MD
3468 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_xio.xio_pages, pidx);
3469
54f51aeb 3470 bp->b_xio.xio_npages = pidx;
3591bbc6
MD
3471 bp->b_data = bp->b_kvabase + ((int)(intptr_t)udata & PAGE_MASK);
3472 bp->b_bcount = bytes;
3473 bp->b_bufsize = bytes;
984263bc
MD
3474 return(0);
3475}
3476
3477/*
3f779080
HP
3478 * vunmapbuf:
3479 *
3480 * Free the io map PTEs associated with this IO operation.
3481 * We also invalidate the TLB entries and restore the original b_addr.
984263bc
MD
3482 */
3483void