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8ceb6160f4
freebsd-skq/sys/kern/vfs_bio.c
dyson 8ceb6160f4 This mega-commit is meant to fix numerous interrelated problems. There 
has been some bitrot and incorrect assumptions in the vfs_bio code.  These
problems have manifest themselves worse on NFS type filesystems, but can
still affect local filesystems under certain circumstances.  Most of
the problems have involved mmap consistancy, and as a side-effect broke
the vfs.ioopt code.  This code might have been committed seperately, but
almost everything is interrelated.

1)	Allow (pmap_object_init_pt) prefaulting of buffer-busy pages that
	are fully valid.
2)	Rather than deactivating erroneously read initial (header) pages in
	kern_exec, we now free them.
3)	Fix the rundown of non-VMIO buffers that are in an inconsistent
	(missing vp) state.
4)	Fix the disassociation of pages from buffers in brelse.  The previous
	code had rotted and was faulty in a couple of important circumstances.
5)	Remove a gratuitious buffer wakeup in vfs_vmio_release.
6)	Remove a crufty and currently unused cluster mechanism for VBLK
	files in vfs_bio_awrite.  When the code is functional, I'll add back
	a cleaner version.
7)	The page busy count wakeups assocated with the buffer cache usage were
	incorrectly cleaned up in a previous commit by me.  Revert to the
	original, correct version, but with a cleaner implementation.
8)	The cluster read code now tries to keep data associated with buffers
	more aggressively (without breaking the heuristics) when it is presumed
	that the read data (buffers) will be soon needed.
9)	Change to filesystem lockmgr locks so that they use LK_NOPAUSE.  The
	delay loop waiting is not useful for filesystem locks, due to the
	length of the time intervals.
10)	Correct and clean-up spec_getpages.
11)	Implement a fully functional nfs_getpages, nfs_putpages.
12)	Fix nfs_write so that modifications are coherent with the NFS data on
	the server disk (at least as well as NFS seems to allow.)
13)	Properly support MS_INVALIDATE on NFS.
14)	Properly pass down MS_INVALIDATE to lower levels of the VM code from
	vm_map_clean.
15)	Better support the notion of pages being busy but valid, so that
	fewer in-transit waits occur.  (use p->busy more for pageouts instead
	of PG_BUSY.)  Since the page is fully valid, it is still usable for
	reads.
16)	It is possible (in error) for cached pages to be busy.  Make the
	page allocation code handle that case correctly.  (It should probably
	be a printf or panic, but I want the system to handle coding errors
	robustly.  I'll probably add a printf.)
17)	Correct the design and usage of vm_page_sleep.  It didn't handle
	consistancy problems very well, so make the design a little less
	lofty.  After vm_page_sleep, if it ever blocked, it is still important
	to relookup the page (if the object generation count changed), and
	verify it's status (always.)
18)	In vm_pageout.c, vm_pageout_clean had rotted, so clean that up.
19)	Push the page busy for writes and VM_PROT_READ into vm_pageout_flush.
20)	Fix vm_pager_put_pages and it's descendents to support an int flag
	instead of a boolean, so that we can pass down the invalidate bit.
1998-03-07 21:37:31 +00:00

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/*
* Copyright (c) 1994,1997 John S. Dyson
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice immediately at the beginning of the file, without modification,
* this list of conditions, and the following disclaimer.
* 2. Absolutely no warranty of function or purpose is made by the author
* John S. Dyson.
*
* $Id: vfs_bio.c,v 1.153 1998/03/04 03:17:30 dyson Exp $
*/
/*
* this file contains a new buffer I/O scheme implementing a coherent
* VM object and buffer cache scheme. Pains have been taken to make
* sure that the performance degradation associated with schemes such
* as this is not realized.
*
* Author: John S. Dyson
* Significant help during the development and debugging phases
* had been provided by David Greenman, also of the FreeBSD core team.
*/
#include "opt_bounce.h"
#define VMIO
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/vmmeter.h>
#include <sys/lock.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_prot.h>
#include <vm/vm_kern.h>
#include <vm/vm_pageout.h>
#include <vm/vm_page.h>
#include <vm/vm_object.h>
#include <vm/vm_extern.h>
#include <vm/vm_map.h>
#include <sys/buf.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/resourcevar.h>
static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
static void vfs_update __P((void));
static struct proc *updateproc;
static struct kproc_desc up_kp = {
"update",
vfs_update,
&updateproc
};
SYSINIT_KT(update, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &up_kp)
struct buf *buf; /* buffer header pool */
struct swqueue bswlist;
static int count_lock_queue __P((void));
static void vm_hold_free_pages(struct buf * bp, vm_offset_t from,
vm_offset_t to);
static void vm_hold_load_pages(struct buf * bp, vm_offset_t from,
vm_offset_t to);
static void vfs_buf_set_valid(struct buf *bp, vm_ooffset_t foff,
vm_offset_t off, vm_offset_t size,
vm_page_t m);
static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
int pageno, vm_page_t m);
static void vfs_clean_pages(struct buf * bp);
static void vfs_setdirty(struct buf *bp);
static void vfs_vmio_release(struct buf *bp);
static void flushdirtybuffers(int slpflag, int slptimeo);
int needsbuffer;
/*
* Internal update daemon, process 3
* The variable vfs_update_wakeup allows for internal syncs.
*/
int vfs_update_wakeup;
/*
* buffers base kva
*/
/*
* bogus page -- for I/O to/from partially complete buffers
* this is a temporary solution to the problem, but it is not
* really that bad. it would be better to split the buffer
* for input in the case of buffers partially already in memory,
* but the code is intricate enough already.
*/
vm_page_t bogus_page;
static vm_offset_t bogus_offset;
static int bufspace, maxbufspace, vmiospace, maxvmiobufspace,
bufmallocspace, maxbufmallocspace;
int numdirtybuffers;
static int lodirtybuffers, hidirtybuffers;
static int numfreebuffers, lofreebuffers, hifreebuffers;
static int kvafreespace;
SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD,
&numdirtybuffers, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW,
&lodirtybuffers, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW,
&hidirtybuffers, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD,
&numfreebuffers, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW,
&lofreebuffers, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW,
&hifreebuffers, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW,
&maxbufspace, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD,
&bufspace, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, maxvmiobufspace, CTLFLAG_RW,
&maxvmiobufspace, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, vmiospace, CTLFLAG_RD,
&vmiospace, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW,
&maxbufmallocspace, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD,
&bufmallocspace, 0, "");
SYSCTL_INT(_vfs, OID_AUTO, kvafreespace, CTLFLAG_RD,
&kvafreespace, 0, "");
static LIST_HEAD(bufhashhdr, buf) bufhashtbl[BUFHSZ], invalhash;
struct bqueues bufqueues[BUFFER_QUEUES] = {0};
extern int vm_swap_size;
#define BUF_MAXUSE 24
#define VFS_BIO_NEED_ANY 1
#define VFS_BIO_NEED_LOWLIMIT 2
#define VFS_BIO_NEED_FREE 4
/*
* Initialize buffer headers and related structures.
*/
void
bufinit()
{
struct buf *bp;
int i;
TAILQ_INIT(&bswlist);
LIST_INIT(&invalhash);
/* first, make a null hash table */
for (i = 0; i < BUFHSZ; i++)
LIST_INIT(&bufhashtbl[i]);
/* next, make a null set of free lists */
for (i = 0; i < BUFFER_QUEUES; i++)
TAILQ_INIT(&bufqueues[i]);
/* finally, initialize each buffer header and stick on empty q */
for (i = 0; i < nbuf; i++) {
bp = &buf[i];
bzero(bp, sizeof *bp);
bp->b_flags = B_INVAL; /* we're just an empty header */
bp->b_dev = NODEV;
bp->b_rcred = NOCRED;
bp->b_wcred = NOCRED;
bp->b_qindex = QUEUE_EMPTY;
bp->b_vnbufs.le_next = NOLIST;
bp->b_generation = 0;
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
LIST_INSERT_HEAD(&invalhash, bp, b_hash);
}
/*
* maxbufspace is currently calculated to support all filesystem blocks
* to be 8K. If you happen to use a 16K filesystem, the size of the buffer
* cache is still the same as it would be for 8K filesystems. This
* keeps the size of the buffer cache "in check" for big block filesystems.
*/
maxbufspace = (nbuf + 8) * DFLTBSIZE;
/*
* reserve 1/3 of the buffers for metadata (VDIR) which might not be VMIO'ed
*/
maxvmiobufspace = 2 * maxbufspace / 3;
/*
* Limit the amount of malloc memory since it is wired permanently into
* the kernel space. Even though this is accounted for in the buffer
* allocation, we don't want the malloced region to grow uncontrolled.
* The malloc scheme improves memory utilization significantly on average
* (small) directories.
*/
maxbufmallocspace = maxbufspace / 20;
/*
* Remove the probability of deadlock conditions by limiting the
* number of dirty buffers.
*/
hidirtybuffers = nbuf / 8 + 20;
lodirtybuffers = nbuf / 16 + 10;
numdirtybuffers = 0;
lofreebuffers = nbuf / 18 + 5;
hifreebuffers = 2 * lofreebuffers;
numfreebuffers = nbuf;
kvafreespace = 0;
bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE);
bogus_page = vm_page_alloc(kernel_object,
((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
VM_ALLOC_NORMAL);
}
/*
* Free the kva allocation for a buffer
* Must be called only at splbio or higher,
* as this is the only locking for buffer_map.
*/
static void
bfreekva(struct buf * bp)
{
if (bp->b_kvasize == 0)
return;
vm_map_delete(buffer_map,
(vm_offset_t) bp->b_kvabase,
(vm_offset_t) bp->b_kvabase + bp->b_kvasize);
bp->b_kvasize = 0;
}
/*
* remove the buffer from the appropriate free list
*/
void
bremfree(struct buf * bp)
{
int s = splbio();
if (bp->b_qindex != QUEUE_NONE) {
if (bp->b_qindex == QUEUE_EMPTY) {
kvafreespace -= bp->b_kvasize;
}
TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
bp->b_qindex = QUEUE_NONE;
} else {
#if !defined(MAX_PERF)
panic("bremfree: removing a buffer when not on a queue");
#endif
}
if ((bp->b_flags & B_INVAL) ||
(bp->b_flags & (B_DELWRI|B_LOCKED)) == 0)
--numfreebuffers;
splx(s);
}
/*
* Get a buffer with the specified data. Look in the cache first.
*/
int
bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
struct buf ** bpp)
{
struct buf *bp;
bp = getblk(vp, blkno, size, 0, 0);
*bpp = bp;
/* if not found in cache, do some I/O */
if ((bp->b_flags & B_CACHE) == 0) {
if (curproc != NULL)
curproc->p_stats->p_ru.ru_inblock++;
bp->b_flags |= B_READ;
bp->b_flags &= ~(B_DONE | B_ERROR | B_INVAL);
if (bp->b_rcred == NOCRED) {
if (cred != NOCRED)
crhold(cred);
bp->b_rcred = cred;
}
vfs_busy_pages(bp, 0);
VOP_STRATEGY(bp);
return (biowait(bp));
}
return (0);
}
/*
* Operates like bread, but also starts asynchronous I/O on
* read-ahead blocks.
*/
int
breadn(struct vnode * vp, daddr_t blkno, int size,
daddr_t * rablkno, int *rabsize,
int cnt, struct ucred * cred, struct buf ** bpp)
{
struct buf *bp, *rabp;
int i;
int rv = 0, readwait = 0;
*bpp = bp = getblk(vp, blkno, size, 0, 0);
/* if not found in cache, do some I/O */
if ((bp->b_flags & B_CACHE) == 0) {
if (curproc != NULL)
curproc->p_stats->p_ru.ru_inblock++;
bp->b_flags |= B_READ;
bp->b_flags &= ~(B_DONE | B_ERROR | B_INVAL);
if (bp->b_rcred == NOCRED) {
if (cred != NOCRED)
crhold(cred);
bp->b_rcred = cred;
}
vfs_busy_pages(bp, 0);
VOP_STRATEGY(bp);
++readwait;
}
for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
if (inmem(vp, *rablkno))
continue;
rabp = getblk(vp, *rablkno, *rabsize, 0, 0);
if ((rabp->b_flags & B_CACHE) == 0) {
if (curproc != NULL)
curproc->p_stats->p_ru.ru_inblock++;
rabp->b_flags |= B_READ | B_ASYNC;
rabp->b_flags &= ~(B_DONE | B_ERROR | B_INVAL);
if (rabp->b_rcred == NOCRED) {
if (cred != NOCRED)
crhold(cred);
rabp->b_rcred = cred;
}
vfs_busy_pages(rabp, 0);
VOP_STRATEGY(rabp);
} else {
brelse(rabp);
}
}
if (readwait) {
rv = biowait(bp);
}
return (rv);
}
/*
* Write, release buffer on completion. (Done by iodone
* if async.)
*/
int
bwrite(struct buf * bp)
{
int oldflags = bp->b_flags;
if (bp->b_flags & B_INVAL) {
brelse(bp);
return (0);
}
#if !defined(MAX_PERF)
if (!(bp->b_flags & B_BUSY))
panic("bwrite: buffer is not busy???");
#endif
bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI);
bp->b_flags |= B_WRITEINPROG;
if ((oldflags & B_DELWRI) == B_DELWRI) {
--numdirtybuffers;
reassignbuf(bp, bp->b_vp);
}
bp->b_vp->v_numoutput++;
vfs_busy_pages(bp, 1);
if (curproc != NULL)
curproc->p_stats->p_ru.ru_oublock++;
VOP_STRATEGY(bp);
if ((oldflags & B_ASYNC) == 0) {
int rtval = biowait(bp);
if (oldflags & B_DELWRI) {
reassignbuf(bp, bp->b_vp);
}
brelse(bp);
return (rtval);
}
return (0);
}
inline void
vfs_bio_need_satisfy(void) {
++numfreebuffers;
if (!needsbuffer)
return;
if (numdirtybuffers < lodirtybuffers) {
needsbuffer &= ~(VFS_BIO_NEED_ANY | VFS_BIO_NEED_LOWLIMIT);
} else {
needsbuffer &= ~VFS_BIO_NEED_ANY;
}
if (numfreebuffers >= hifreebuffers) {
needsbuffer &= ~VFS_BIO_NEED_FREE;
}
wakeup(&needsbuffer);
}
/*
* Delayed write. (Buffer is marked dirty).
*/
void
bdwrite(struct buf * bp)
{
#if !defined(MAX_PERF)
if ((bp->b_flags & B_BUSY) == 0) {
panic("bdwrite: buffer is not busy");
}
#endif
if (bp->b_flags & B_INVAL) {
brelse(bp);
return;
}
if (bp->b_flags & B_TAPE) {
bawrite(bp);
return;
}
bp->b_flags &= ~(B_READ|B_RELBUF);
if ((bp->b_flags & B_DELWRI) == 0) {
bp->b_flags |= B_DONE | B_DELWRI;
reassignbuf(bp, bp->b_vp);
++numdirtybuffers;
}
/*
* This bmap keeps the system from needing to do the bmap later,
* perhaps when the system is attempting to do a sync. Since it
* is likely that the indirect block -- or whatever other datastructure
* that the filesystem needs is still in memory now, it is a good
* thing to do this. Note also, that if the pageout daemon is
* requesting a sync -- there might not be enough memory to do
* the bmap then... So, this is important to do.
*/
if (bp->b_lblkno == bp->b_blkno) {
VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
}
/*
* Set the *dirty* buffer range based upon the VM system dirty pages.
*/
vfs_setdirty(bp);
/*
* We need to do this here to satisfy the vnode_pager and the
* pageout daemon, so that it thinks that the pages have been
* "cleaned". Note that since the pages are in a delayed write
* buffer -- the VFS layer "will" see that the pages get written
* out on the next sync, or perhaps the cluster will be completed.
*/
vfs_clean_pages(bp);
bqrelse(bp);
if (numdirtybuffers >= hidirtybuffers)
flushdirtybuffers(0, 0);
return;
}
/*
* Asynchronous write.
* Start output on a buffer, but do not wait for it to complete.
* The buffer is released when the output completes.
*/
void
bawrite(struct buf * bp)
{
bp->b_flags |= B_ASYNC;
(void) VOP_BWRITE(bp);
}
/*
* Ordered write.
* Start output on a buffer, but only wait for it to complete if the
* output device cannot guarantee ordering in some other way. Devices
* that can perform asynchronous ordered writes will set the B_ASYNC
* flag in their strategy routine.
* The buffer is released when the output completes.
*/
int
bowrite(struct buf * bp)
{
/*
* XXX Add in B_ASYNC once the SCSI
* layer can deal with ordered
* writes properly.
*/
bp->b_flags |= B_ORDERED;
return (VOP_BWRITE(bp));
}
/*
* Release a buffer.
*/
void
brelse(struct buf * bp)
{
int s;
if (bp->b_flags & B_CLUSTER) {
relpbuf(bp);
return;
}
s = splbio();
/* anyone need this block? */
if (bp->b_flags & B_WANTED) {
bp->b_flags &= ~(B_WANTED | B_AGE);
wakeup(bp);
}
if (bp->b_flags & B_LOCKED)
bp->b_flags &= ~B_ERROR;
if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) ||
(bp->b_bufsize <= 0)) {
bp->b_flags |= B_INVAL;
if (bp->b_flags & B_DELWRI)
--numdirtybuffers;
bp->b_flags &= ~(B_DELWRI | B_CACHE);
if ((bp->b_flags & B_VMIO) == 0) {
if (bp->b_bufsize)
allocbuf(bp, 0);
if (bp->b_vp)
brelvp(bp);
}
}
/*
* VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
* constituted, so the B_INVAL flag is used to *invalidate* the buffer,
* but the VM object is kept around. The B_NOCACHE flag is used to
* invalidate the pages in the VM object.
*
* If the buffer is a partially filled NFS buffer, keep it
* since invalidating it now will lose informatio. The valid
* flags in the vm_pages have only DEV_BSIZE resolution but
* the b_validoff, b_validend fields have byte resolution.
* This can avoid unnecessary re-reads of the buffer.
* XXX this seems to cause performance problems.
*/
if ((bp->b_flags & B_VMIO)
&& !(bp->b_vp->v_tag == VT_NFS &&
bp->b_vp->v_type != VBLK &&
(bp->b_flags & B_DELWRI) != 0)
#ifdef notdef
&& (bp->b_vp->v_tag != VT_NFS
|| bp->b_vp->v_type == VBLK
|| (bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR))
|| bp->b_validend == 0
|| (bp->b_validoff == 0
&& bp->b_validend == bp->b_bufsize))
#endif
) {
int i, j, resid;
vm_page_t m;
off_t foff;
vm_pindex_t poff;
vm_object_t obj;
struct vnode *vp;
int blksize;
vp = bp->b_vp;
if (vp->v_type == VBLK)
blksize = DEV_BSIZE;
else
blksize = vp->v_mount->mnt_stat.f_iosize;
resid = bp->b_bufsize;
foff = -1LL;
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if (m == bogus_page) {
obj = (vm_object_t) vp->v_object;
foff = (off_t) bp->b_lblkno * blksize;
poff = OFF_TO_IDX(foff);
for (j = i; j < bp->b_npages; j++) {
m = bp->b_pages[j];
if (m == bogus_page) {
m = vm_page_lookup(obj, poff + j);
#if !defined(MAX_PERF)
if (!m) {
panic("brelse: page missing\n");
}
#endif
bp->b_pages[j] = m;
}
}
if ((bp->b_flags & B_INVAL) == 0) {
pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages);
}
break;
}
if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
if ((blksize & PAGE_MASK) == 0) {
vm_page_set_invalid(m, 0, resid);
} else {
if (foff == -1LL)
foff = (off_t) bp->b_lblkno * blksize;
vm_page_set_invalid(m, (vm_offset_t) foff, resid);
}
}
resid -= PAGE_SIZE;
}
if (bp->b_flags & (B_INVAL | B_RELBUF))
vfs_vmio_release(bp);
} else if (bp->b_flags & B_VMIO) {
if (bp->b_flags & (B_INVAL | B_RELBUF))
vfs_vmio_release(bp);
}
#if !defined(MAX_PERF)
if (bp->b_qindex != QUEUE_NONE)
panic("brelse: free buffer onto another queue???");
#endif
/* enqueue */
/* buffers with no memory */
if (bp->b_bufsize == 0) {
bp->b_flags |= B_INVAL;
bp->b_qindex = QUEUE_EMPTY;
TAILQ_INSERT_HEAD(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
LIST_REMOVE(bp, b_hash);
LIST_INSERT_HEAD(&invalhash, bp, b_hash);
bp->b_dev = NODEV;
kvafreespace += bp->b_kvasize;
bp->b_generation++;
/* buffers with junk contents */
} else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) {
bp->b_flags |= B_INVAL;
bp->b_qindex = QUEUE_AGE;
TAILQ_INSERT_HEAD(&bufqueues[QUEUE_AGE], bp, b_freelist);
LIST_REMOVE(bp, b_hash);
LIST_INSERT_HEAD(&invalhash, bp, b_hash);
bp->b_dev = NODEV;
bp->b_generation++;
/* buffers that are locked */
} else if (bp->b_flags & B_LOCKED) {
bp->b_qindex = QUEUE_LOCKED;
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist);
/* buffers with stale but valid contents */
} else if (bp->b_flags & B_AGE) {
bp->b_qindex = QUEUE_AGE;
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_AGE], bp, b_freelist);
/* buffers with valid and quite potentially reuseable contents */
} else {
bp->b_qindex = QUEUE_LRU;
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
}
if ((bp->b_flags & B_INVAL) ||
(bp->b_flags & (B_LOCKED|B_DELWRI)) == 0) {
if (bp->b_flags & B_DELWRI) {
--numdirtybuffers;
bp->b_flags &= ~B_DELWRI;
}
vfs_bio_need_satisfy();
}
/* unlock */
bp->b_flags &= ~(B_ORDERED | B_WANTED | B_BUSY |
B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
splx(s);
}
/*
* Release a buffer.
*/
void
bqrelse(struct buf * bp)
{
int s;
s = splbio();
/* anyone need this block? */
if (bp->b_flags & B_WANTED) {
bp->b_flags &= ~(B_WANTED | B_AGE);
wakeup(bp);
}
#if !defined(MAX_PERF)
if (bp->b_qindex != QUEUE_NONE)
panic("bqrelse: free buffer onto another queue???");
#endif
if (bp->b_flags & B_LOCKED) {
bp->b_flags &= ~B_ERROR;
bp->b_qindex = QUEUE_LOCKED;
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist);
/* buffers with stale but valid contents */
} else {
bp->b_qindex = QUEUE_LRU;
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
}
if ((bp->b_flags & (B_LOCKED|B_DELWRI)) == 0) {
vfs_bio_need_satisfy();
}
/* unlock */
bp->b_flags &= ~(B_ORDERED | B_WANTED | B_BUSY |
B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
splx(s);
}
static void
vfs_vmio_release(bp)
struct buf *bp;
{
int i;
vm_page_t m;
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
bp->b_pages[i] = NULL;
vm_page_unwire(m);
/*
* We don't mess with busy pages, it is
* the responsibility of the process that
* busied the pages to deal with them.
*/
if ((m->flags & PG_BUSY) || (m->busy != 0))
continue;
if (m->wire_count == 0) {
/*
* If this is an async free -- we cannot place
* pages onto the cache queue. If it is an
* async free, then we don't modify any queues.
* This is probably in error (for perf reasons),
* and we will eventually need to build
* a more complete infrastructure to support I/O
* rundown.
*/
if ((bp->b_flags & B_ASYNC) == 0) {
/*
* In the case of sync buffer frees, we can do pretty much
* anything to any of the memory queues. Specifically,
* the cache queue is okay to be modified.
*/
if (m->valid) {
if(m->dirty == 0)
vm_page_test_dirty(m);
/*
* this keeps pressure off of the process memory
*/
if (m->dirty == 0 && m->hold_count == 0)
vm_page_cache(m);
else
vm_page_deactivate(m);
} else if (m->hold_count == 0) {
m->flags |= PG_BUSY;
vm_page_protect(m, VM_PROT_NONE);
vm_page_free(m);
}
} else {
/*
* If async, then at least we clear the
* act_count.
*/
m->act_count = 0;
}
}
}
bufspace -= bp->b_bufsize;
vmiospace -= bp->b_bufsize;
pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
bp->b_npages = 0;
bp->b_bufsize = 0;
bp->b_flags &= ~B_VMIO;
if (bp->b_vp)
brelvp(bp);
}
/*
* Check to see if a block is currently memory resident.
*/
struct buf *
gbincore(struct vnode * vp, daddr_t blkno)
{
struct buf *bp;
struct bufhashhdr *bh;
bh = BUFHASH(vp, blkno);
bp = bh->lh_first;
/* Search hash chain */
while (bp != NULL) {
/* hit */
if (bp->b_vp == vp && bp->b_lblkno == blkno &&
(bp->b_flags & B_INVAL) == 0) {
break;
}
bp = bp->b_hash.le_next;
}
return (bp);
}
/*
* this routine implements clustered async writes for
* clearing out B_DELWRI buffers... This is much better
* than the old way of writing only one buffer at a time.
*/
int
vfs_bio_awrite(struct buf * bp)
{
int i;
daddr_t lblkno = bp->b_lblkno;
struct vnode *vp = bp->b_vp;
int s;
int ncl;
struct buf *bpa;
int nwritten;
int size;
int maxcl;
s = splbio();
/*
* right now we support clustered writing only to regular files
*/
if ((vp->v_type == VREG) &&
(vp->v_mount != 0) && /* Only on nodes that have the size info */
(bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
size = vp->v_mount->mnt_stat.f_iosize;
maxcl = MAXPHYS / size;
for (i = 1; i < maxcl; i++) {
if ((bpa = gbincore(vp, lblkno + i)) &&
((bpa->b_flags & (B_BUSY | B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
(B_DELWRI | B_CLUSTEROK)) &&
(bpa->b_bufsize == size)) {
if ((bpa->b_blkno == bpa->b_lblkno) ||
(bpa->b_blkno != bp->b_blkno + ((i * size) >> DEV_BSHIFT)))
break;
} else {
break;
}
}
ncl = i;
/*
* this is a possible cluster write
*/
if (ncl != 1) {
nwritten = cluster_wbuild(vp, size, lblkno, ncl);
splx(s);
return nwritten;
}
}
bremfree(bp);
splx(s);
/*
* default (old) behavior, writing out only one block
*/
bp->b_flags |= B_BUSY | B_ASYNC;
nwritten = bp->b_bufsize;
(void) VOP_BWRITE(bp);
return nwritten;
}
/*
* Find a buffer header which is available for use.
*/
static struct buf *
getnewbuf(struct vnode *vp, daddr_t blkno,
int slpflag, int slptimeo, int size, int maxsize)
{
struct buf *bp, *bp1;
int nbyteswritten = 0;
vm_offset_t addr;
static int writerecursion = 0;
start:
if (bufspace >= maxbufspace)
goto trytofreespace;
/* can we constitute a new buffer? */
if ((bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]))) {
#if !defined(MAX_PERF)
if (bp->b_qindex != QUEUE_EMPTY)
panic("getnewbuf: inconsistent EMPTY queue, qindex=%d",
bp->b_qindex);
#endif
bp->b_flags |= B_BUSY;
bremfree(bp);
goto fillbuf;
}
trytofreespace:
/*
* We keep the file I/O from hogging metadata I/O
* This is desirable because file data is cached in the
* VM/Buffer cache even if a buffer is freed.
*/
if ((bp = TAILQ_FIRST(&bufqueues[QUEUE_AGE]))) {
#if !defined(MAX_PERF)
if (bp->b_qindex != QUEUE_AGE)
panic("getnewbuf: inconsistent AGE queue, qindex=%d",
bp->b_qindex);
#endif
} else if ((bp = TAILQ_FIRST(&bufqueues[QUEUE_LRU]))) {
#if !defined(MAX_PERF)
if (bp->b_qindex != QUEUE_LRU)
panic("getnewbuf: inconsistent LRU queue, qindex=%d",
bp->b_qindex);
#endif
}
if (!bp) {
/* wait for a free buffer of any kind */
needsbuffer |= VFS_BIO_NEED_ANY;
do
tsleep(&needsbuffer, (PRIBIO + 1) | slpflag, "newbuf",
slptimeo);
while (needsbuffer & VFS_BIO_NEED_ANY);
return (0);
}
#if defined(DIAGNOSTIC)
if (bp->b_flags & B_BUSY) {
panic("getnewbuf: busy buffer on free list\n");
}
#endif
/*
* We are fairly aggressive about freeing VMIO buffers, but since
* the buffering is intact without buffer headers, there is not
* much loss. We gain by maintaining non-VMIOed metadata in buffers.
*/
if ((bp->b_qindex == QUEUE_LRU) && (bp->b_usecount > 0)) {
if ((bp->b_flags & B_VMIO) == 0 ||
(vmiospace < maxvmiobufspace)) {
--bp->b_usecount;
TAILQ_REMOVE(&bufqueues[QUEUE_LRU], bp, b_freelist);
if (TAILQ_FIRST(&bufqueues[QUEUE_LRU]) != NULL) {
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
goto start;
}
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
}
}
/* if we are a delayed write, convert to an async write */
if ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) {
/*
* If our delayed write is likely to be used soon, then
* recycle back onto the LRU queue.
*/
if (vp && (bp->b_vp == vp) && (bp->b_qindex == QUEUE_LRU) &&
(bp->b_lblkno >= blkno) && (maxsize > 0)) {
if (bp->b_usecount > 0) {
if (bp->b_lblkno < blkno + (MAXPHYS / maxsize)) {
TAILQ_REMOVE(&bufqueues[QUEUE_LRU], bp, b_freelist);
if (TAILQ_FIRST(&bufqueues[QUEUE_LRU]) != NULL) {
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
bp->b_usecount--;
goto start;
}
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
}
}
}
/*
* Certain layered filesystems can recursively re-enter the vfs_bio
* code, due to delayed writes. This helps keep the system from
* deadlocking.
*/
if (writerecursion > 0) {
bp = TAILQ_FIRST(&bufqueues[QUEUE_AGE]);
while (bp) {
if ((bp->b_flags & B_DELWRI) == 0)
break;
bp = TAILQ_NEXT(bp, b_freelist);
}
if (bp == NULL) {
bp = TAILQ_FIRST(&bufqueues[QUEUE_LRU]);
while (bp) {
if ((bp->b_flags & B_DELWRI) == 0)
break;
bp = TAILQ_NEXT(bp, b_freelist);
}
}
if (bp == NULL)
panic("getnewbuf: cannot get buffer, infinite recursion failure");
} else {
++writerecursion;
nbyteswritten += vfs_bio_awrite(bp);
--writerecursion;
if (!slpflag && !slptimeo) {
return (0);
}
goto start;
}
}
if (bp->b_flags & B_WANTED) {
bp->b_flags &= ~B_WANTED;
wakeup(bp);
}
bremfree(bp);
bp->b_flags |= B_BUSY;
if (bp->b_flags & B_VMIO) {
bp->b_flags &= ~B_ASYNC;
vfs_vmio_release(bp);
}
if (bp->b_vp)
brelvp(bp);
fillbuf:
bp->b_generation++;
/* we are not free, nor do we contain interesting data */
if (bp->b_rcred != NOCRED) {
crfree(bp->b_rcred);
bp->b_rcred = NOCRED;
}
if (bp->b_wcred != NOCRED) {
crfree(bp->b_wcred);
bp->b_wcred = NOCRED;
}
LIST_REMOVE(bp, b_hash);
LIST_INSERT_HEAD(&invalhash, bp, b_hash);
if (bp->b_bufsize) {
allocbuf(bp, 0);
}
bp->b_flags = B_BUSY;
bp->b_dev = NODEV;
bp->b_vp = NULL;
bp->b_blkno = bp->b_lblkno = 0;
bp->b_iodone = 0;
bp->b_error = 0;
bp->b_resid = 0;
bp->b_bcount = 0;
bp->b_npages = 0;
bp->b_dirtyoff = bp->b_dirtyend = 0;
bp->b_validoff = bp->b_validend = 0;
bp->b_usecount = 5;
maxsize = (maxsize + PAGE_MASK) & ~PAGE_MASK;
/*
* we assume that buffer_map is not at address 0
*/
addr = 0;
if (maxsize != bp->b_kvasize) {
bfreekva(bp);
findkvaspace:
/*
* See if we have buffer kva space
*/
if (vm_map_findspace(buffer_map,
vm_map_min(buffer_map), maxsize, &addr)) {
if (kvafreespace > 0) {
int totfree = 0, freed;
do {
freed = 0;
for (bp1 = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
bp1 != NULL; bp1 = TAILQ_NEXT(bp1, b_freelist)) {
if (bp1->b_kvasize != 0) {
totfree += bp1->b_kvasize;
freed = bp1->b_kvasize;
bremfree(bp1);
bfreekva(bp1);
brelse(bp1);
break;
}
}
} while (freed);
/*
* if we found free space, then retry with the same buffer.
*/
if (totfree)
goto findkvaspace;
}
bp->b_flags |= B_INVAL;
brelse(bp);
goto trytofreespace;
}
}
/*
* See if we are below are allocated minimum
*/
if (bufspace >= (maxbufspace + nbyteswritten)) {
bp->b_flags |= B_INVAL;
brelse(bp);
goto trytofreespace;
}
/*
* create a map entry for the buffer -- in essence
* reserving the kva space.
*/
if (addr) {
vm_map_insert(buffer_map, NULL, 0,
addr, addr + maxsize,
VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
bp->b_kvabase = (caddr_t) addr;
bp->b_kvasize = maxsize;
}
bp->b_data = bp->b_kvabase;
return (bp);
}
static void
waitfreebuffers(int slpflag, int slptimeo) {
while (numfreebuffers < hifreebuffers) {
flushdirtybuffers(slpflag, slptimeo);
if (numfreebuffers < hifreebuffers)
break;
needsbuffer |= VFS_BIO_NEED_FREE;
if (tsleep(&needsbuffer, PRIBIO|slpflag, "biofre", slptimeo))
break;
}
}
static void
flushdirtybuffers(int slpflag, int slptimeo) {
int s;
static pid_t flushing = 0;
s = splbio();
if (flushing) {
if (flushing == curproc->p_pid) {
splx(s);
return;
}
while (flushing) {
if (tsleep(&flushing, PRIBIO|slpflag, "biofls", slptimeo)) {
splx(s);
return;
}
}
}
flushing = curproc->p_pid;
while (numdirtybuffers > lodirtybuffers) {
struct buf *bp;
needsbuffer |= VFS_BIO_NEED_LOWLIMIT;
bp = TAILQ_FIRST(&bufqueues[QUEUE_AGE]);
if (bp == NULL)
bp = TAILQ_FIRST(&bufqueues[QUEUE_LRU]);
while (bp && ((bp->b_flags & B_DELWRI) == 0)) {
bp = TAILQ_NEXT(bp, b_freelist);
}
if (bp) {
vfs_bio_awrite(bp);
continue;
}
break;
}
flushing = 0;
wakeup(&flushing);
splx(s);
}
/*
* Check to see if a block is currently memory resident.
*/
struct buf *
incore(struct vnode * vp, daddr_t blkno)
{
struct buf *bp;
int s = splbio();
bp = gbincore(vp, blkno);
splx(s);
return (bp);
}
/*
* Returns true if no I/O is needed to access the
* associated VM object. This is like incore except
* it also hunts around in the VM system for the data.
*/
int
inmem(struct vnode * vp, daddr_t blkno)
{
vm_object_t obj;
vm_offset_t toff, tinc;
vm_page_t m;
vm_ooffset_t off;
if (incore(vp, blkno))
return 1;
if (vp->v_mount == NULL)
return 0;
if ((vp->v_object == NULL) || (vp->v_flag & VOBJBUF) == 0)
return 0;
obj = vp->v_object;
tinc = PAGE_SIZE;
if (tinc > vp->v_mount->mnt_stat.f_iosize)
tinc = vp->v_mount->mnt_stat.f_iosize;
off = blkno * vp->v_mount->mnt_stat.f_iosize;
for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
if (!m)
return 0;
if (vm_page_is_valid(m, (vm_offset_t) (toff + off), tinc) == 0)
return 0;
}
return 1;
}
/*
* now we set the dirty range for the buffer --
* for NFS -- if the file is mapped and pages have
* been written to, let it know. We want the
* entire range of the buffer to be marked dirty if
* any of the pages have been written to for consistancy
* with the b_validoff, b_validend set in the nfs write
* code, and used by the nfs read code.
*/
static void
vfs_setdirty(struct buf *bp) {
int i;
vm_object_t object;
vm_offset_t boffset, offset;
/*
* We qualify the scan for modified pages on whether the
* object has been flushed yet. The OBJ_WRITEABLE flag
* is not cleared simply by protecting pages off.
*/
if ((bp->b_flags & B_VMIO) &&
((object = bp->b_pages[0]->object)->flags & (OBJ_WRITEABLE|OBJ_CLEANING))) {
/*
* test the pages to see if they have been modified directly
* by users through the VM system.
*/
for (i = 0; i < bp->b_npages; i++)
vm_page_test_dirty(bp->b_pages[i]);
/*
* scan forwards for the first page modified
*/
for (i = 0; i < bp->b_npages; i++) {
if (bp->b_pages[i]->dirty) {
break;
}
}
boffset = (i << PAGE_SHIFT);
if (boffset < bp->b_dirtyoff) {
bp->b_dirtyoff = boffset;
}
/*
* scan backwards for the last page modified
*/
for (i = bp->b_npages - 1; i >= 0; --i) {
if (bp->b_pages[i]->dirty) {
break;
}
}
boffset = (i + 1);
offset = boffset + bp->b_pages[0]->pindex;
if (offset >= object->size)
boffset = object->size - bp->b_pages[0]->pindex;
if (bp->b_dirtyend < (boffset << PAGE_SHIFT))
bp->b_dirtyend = (boffset << PAGE_SHIFT);
}
}
/*
* Get a block given a specified block and offset into a file/device.
*/
struct buf *
getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)
{
struct buf *bp;
int i, s;
struct bufhashhdr *bh;
int maxsize;
int generation;
if (vp->v_mount) {
maxsize = vp->v_mount->mnt_stat.f_iosize;
/*
* This happens on mount points.
*/
if (maxsize < size)
maxsize = size;
} else {
maxsize = size;
}
#if !defined(MAX_PERF)
if (size > MAXBSIZE)
panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
#endif
s = splbio();
loop:
if (numfreebuffers < lofreebuffers) {
waitfreebuffers(slpflag, slptimeo);
}
if ((bp = gbincore(vp, blkno))) {
loop1:
generation = bp->b_generation;
if (bp->b_flags & B_BUSY) {
bp->b_flags |= B_WANTED;
if (bp->b_usecount < BUF_MAXUSE)
++bp->b_usecount;
if (!tsleep(bp,
(PRIBIO + 1) | slpflag, "getblk", slptimeo)) {
if (bp->b_generation != generation)
goto loop;
goto loop1;
} else {
splx(s);
return (struct buf *) NULL;
}
}
bp->b_flags |= B_BUSY | B_CACHE;
bremfree(bp);
/*
* check for size inconsistancies (note that they shouldn't
* happen but do when filesystems don't handle the size changes
* correctly.) We are conservative on metadata and don't just
* extend the buffer but write and re-constitute it.
*/
if (bp->b_bcount != size) {
bp->b_generation++;
if ((bp->b_flags & B_VMIO) && (size <= bp->b_kvasize)) {
allocbuf(bp, size);
} else {
bp->b_flags |= B_NOCACHE;
VOP_BWRITE(bp);
goto loop;
}
}
if (bp->b_usecount < BUF_MAXUSE)
++bp->b_usecount;
splx(s);
return (bp);
} else {
vm_object_t obj;
if ((bp = getnewbuf(vp, blkno,
slpflag, slptimeo, size, maxsize)) == 0) {
if (slpflag || slptimeo) {
splx(s);
return NULL;
}
goto loop;
}
/*
* This code is used to make sure that a buffer is not
* created while the getnewbuf routine is blocked.
* Normally the vnode is locked so this isn't a problem.
* VBLK type I/O requests, however, don't lock the vnode.
*/
if (!VOP_ISLOCKED(vp) && gbincore(vp, blkno)) {
bp->b_flags |= B_INVAL;
brelse(bp);
goto loop;
}
/*
* Insert the buffer into the hash, so that it can
* be found by incore.
*/
bp->b_blkno = bp->b_lblkno = blkno;
bgetvp(vp, bp);
LIST_REMOVE(bp, b_hash);
bh = BUFHASH(vp, blkno);
LIST_INSERT_HEAD(bh, bp, b_hash);
if ((obj = vp->v_object) && (vp->v_flag & VOBJBUF)) {
bp->b_flags |= (B_VMIO | B_CACHE);
#if defined(VFS_BIO_DEBUG)
if (vp->v_type != VREG && vp->v_type != VBLK)
printf("getblk: vmioing file type %d???\n", vp->v_type);
#endif
} else {
bp->b_flags &= ~B_VMIO;
}
allocbuf(bp, size);
splx(s);
#ifdef PC98
/*
* 1024byte/sector support
*/
#define B_XXX2 0x8000000
if (vp->v_flag & 0x10000) bp->b_flags |= B_XXX2;
#endif
return (bp);
}
}
/*
* Get an empty, disassociated buffer of given size.
*/
struct buf *
geteblk(int size)
{
struct buf *bp;
int s;
s = splbio();
while ((bp = getnewbuf(0, (daddr_t) 0, 0, 0, size, MAXBSIZE)) == 0);
splx(s);
allocbuf(bp, size);
bp->b_flags |= B_INVAL;
return (bp);
}
/*
* This code constitutes the buffer memory from either anonymous system
* memory (in the case of non-VMIO operations) or from an associated
* VM object (in the case of VMIO operations).
*
* Note that this code is tricky, and has many complications to resolve
* deadlock or inconsistant data situations. Tread lightly!!!
*
* Modify the length of a buffer's underlying buffer storage without
* destroying information (unless, of course the buffer is shrinking).
*/
int
allocbuf(struct buf * bp, int size)
{
int s;
int newbsize, mbsize;
int i;
#if !defined(MAX_PERF)
if (!(bp->b_flags & B_BUSY))
panic("allocbuf: buffer not busy");
if (bp->b_kvasize < size)
panic("allocbuf: buffer too small");
#endif
if ((bp->b_flags & B_VMIO) == 0) {
caddr_t origbuf;
int origbufsize;
/*
* Just get anonymous memory from the kernel
*/
mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
#if !defined(NO_B_MALLOC)
if (bp->b_flags & B_MALLOC)
newbsize = mbsize;
else
#endif
newbsize = round_page(size);
if (newbsize < bp->b_bufsize) {
#if !defined(NO_B_MALLOC)
/*
* malloced buffers are not shrunk
*/
if (bp->b_flags & B_MALLOC) {
if (newbsize) {
bp->b_bcount = size;
} else {
free(bp->b_data, M_BIOBUF);
bufspace -= bp->b_bufsize;
bufmallocspace -= bp->b_bufsize;
bp->b_data = bp->b_kvabase;
bp->b_bufsize = 0;
bp->b_bcount = 0;
bp->b_flags &= ~B_MALLOC;
}
return 1;
}
#endif
vm_hold_free_pages(
bp,
(vm_offset_t) bp->b_data + newbsize,
(vm_offset_t) bp->b_data + bp->b_bufsize);
} else if (newbsize > bp->b_bufsize) {
#if !defined(NO_B_MALLOC)
/*
* We only use malloced memory on the first allocation.
* and revert to page-allocated memory when the buffer grows.
*/
if ( (bufmallocspace < maxbufmallocspace) &&
(bp->b_bufsize == 0) &&
(mbsize <= PAGE_SIZE/2)) {
bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
bp->b_bufsize = mbsize;
bp->b_bcount = size;
bp->b_flags |= B_MALLOC;
bufspace += mbsize;
bufmallocspace += mbsize;
return 1;
}
#endif
origbuf = NULL;
origbufsize = 0;
#if !defined(NO_B_MALLOC)
/*
* If the buffer is growing on it's other-than-first allocation,
* then we revert to the page-allocation scheme.
*/
if (bp->b_flags & B_MALLOC) {
origbuf = bp->b_data;
origbufsize = bp->b_bufsize;
bp->b_data = bp->b_kvabase;
bufspace -= bp->b_bufsize;
bufmallocspace -= bp->b_bufsize;
bp->b_bufsize = 0;
bp->b_flags &= ~B_MALLOC;
newbsize = round_page(newbsize);
}
#endif
vm_hold_load_pages(
bp,
(vm_offset_t) bp->b_data + bp->b_bufsize,
(vm_offset_t) bp->b_data + newbsize);
#if !defined(NO_B_MALLOC)
if (origbuf) {
bcopy(origbuf, bp->b_data, origbufsize);
free(origbuf, M_BIOBUF);
}
#endif
}
} else {
vm_page_t m;
int desiredpages;
newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
desiredpages = (round_page(newbsize) >> PAGE_SHIFT);
#if !defined(NO_B_MALLOC)
if (bp->b_flags & B_MALLOC)
panic("allocbuf: VMIO buffer can't be malloced");
#endif
if (newbsize < bp->b_bufsize) {
if (desiredpages < bp->b_npages) {
for (i = desiredpages; i < bp->b_npages; i++) {
/*
* the page is not freed here -- it
* is the responsibility of vnode_pager_setsize
*/
m = bp->b_pages[i];
#if defined(DIAGNOSTIC)
if (m == bogus_page)
panic("allocbuf: bogus page found");
#endif
vm_page_sleep(m, "biodep", &m->busy);
bp->b_pages[i] = NULL;
vm_page_unwire(m);
}
pmap_qremove((vm_offset_t) trunc_page(bp->b_data) +
(desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
bp->b_npages = desiredpages;
}
} else if (newbsize > bp->b_bufsize) {
vm_object_t obj;
vm_offset_t tinc, toff;
vm_ooffset_t off;
vm_pindex_t objoff;
int pageindex, curbpnpages;
struct vnode *vp;
int bsize;
int orig_validoff = bp->b_validoff;
int orig_validend = bp->b_validend;
vp = bp->b_vp;
if (vp->v_type == VBLK)
bsize = DEV_BSIZE;
else
bsize = vp->v_mount->mnt_stat.f_iosize;
if (bp->b_npages < desiredpages) {
obj = vp->v_object;
tinc = PAGE_SIZE;
if (tinc > bsize)
tinc = bsize;
off = (vm_ooffset_t) bp->b_lblkno * bsize;
curbpnpages = bp->b_npages;
doretry:
bp->b_validoff = orig_validoff;
bp->b_validend = orig_validend;
bp->b_flags |= B_CACHE;
for (toff = 0; toff < newbsize; toff += tinc) {
int bytesinpage;
pageindex = toff >> PAGE_SHIFT;
objoff = OFF_TO_IDX(off + toff);
if (pageindex < curbpnpages) {
m = bp->b_pages[pageindex];
#ifdef VFS_BIO_DIAG
if (m->pindex != objoff)
panic("allocbuf: page changed offset??!!!?");
#endif
bytesinpage = tinc;
if (tinc > (newbsize - toff))
bytesinpage = newbsize - toff;
if (bp->b_flags & B_CACHE)
vfs_buf_set_valid(bp, off, toff, bytesinpage, m);
continue;
}
m = vm_page_lookup(obj, objoff);
if (!m) {
m = vm_page_alloc(obj, objoff, VM_ALLOC_NORMAL);
if (!m) {
VM_WAIT;
vm_pageout_deficit += (desiredpages - bp->b_npages);
goto doretry;
}
vm_page_wire(m);
m->flags &= ~PG_BUSY;
bp->b_flags &= ~B_CACHE;
} else if (m->flags & PG_BUSY) {
s = splvm();
if (m->flags & PG_BUSY) {
m->flags |= PG_WANTED;
tsleep(m, PVM, "pgtblk", 0);
}
splx(s);
goto doretry;
} else {
if ((curproc != pageproc) &&
((m->queue - m->pc) == PQ_CACHE) &&
((cnt.v_free_count + cnt.v_cache_count) <
(cnt.v_free_min + cnt.v_cache_min))) {
pagedaemon_wakeup();
}
bytesinpage = tinc;
if (tinc > (newbsize - toff))
bytesinpage = newbsize - toff;
if (bp->b_flags & B_CACHE)
vfs_buf_set_valid(bp, off, toff, bytesinpage, m);
vm_page_wire(m);
}
bp->b_pages[pageindex] = m;
curbpnpages = pageindex + 1;
}
if (vp->v_tag == VT_NFS &&
vp->v_type != VBLK) {
if (bp->b_dirtyend > 0) {
bp->b_validoff = min(bp->b_validoff, bp->b_dirtyoff);
bp->b_validend = max(bp->b_validend, bp->b_dirtyend);
}
if (bp->b_validend == 0)
bp->b_flags &= ~B_CACHE;
}
bp->b_data = (caddr_t) trunc_page(bp->b_data);
bp->b_npages = curbpnpages;
pmap_qenter((vm_offset_t) bp->b_data,
bp->b_pages, bp->b_npages);
((vm_offset_t) bp->b_data) |= off & PAGE_MASK;
}
}
}
if (bp->b_flags & B_VMIO)
vmiospace += (newbsize - bp->b_bufsize);
bufspace += (newbsize - bp->b_bufsize);
bp->b_bufsize = newbsize;
bp->b_bcount = size;
return 1;
}
/*
* Wait for buffer I/O completion, returning error status.
*/
int
biowait(register struct buf * bp)
{
int s;
s = splbio();
while ((bp->b_flags & B_DONE) == 0)
#if defined(NO_SCHEDULE_MODS)
tsleep(bp, PRIBIO, "biowait", 0);
#else
if (bp->b_flags & B_READ)
tsleep(bp, PRIBIO, "biord", 0);
else
tsleep(bp, curproc->p_usrpri, "biowr", 0);
#endif
splx(s);
if (bp->b_flags & B_EINTR) {
bp->b_flags &= ~B_EINTR;
return (EINTR);
}
if (bp->b_flags & B_ERROR) {
return (bp->b_error ? bp->b_error : EIO);
} else {
return (0);
}
}
/*
* Finish I/O on a buffer, calling an optional function.
* This is usually called from interrupt level, so process blocking
* is not *a good idea*.
*/
void
biodone(register struct buf * bp)
{
int s;
s = splbio();
#if !defined(MAX_PERF)
if (!(bp->b_flags & B_BUSY))
panic("biodone: buffer not busy");
#endif
if (bp->b_flags & B_DONE) {
splx(s);
#if !defined(MAX_PERF)
printf("biodone: buffer already done\n");
#endif
return;
}
bp->b_flags |= B_DONE;
if ((bp->b_flags & B_READ) == 0) {
vwakeup(bp);
}
#ifdef BOUNCE_BUFFERS
if (bp->b_flags & B_BOUNCE)
vm_bounce_free(bp);
#endif
/* call optional completion function if requested */
if (bp->b_flags & B_CALL) {
bp->b_flags &= ~B_CALL;
(*bp->b_iodone) (bp);
splx(s);
return;
}
if (bp->b_flags & B_VMIO) {
int i, resid;
vm_ooffset_t foff;
vm_page_t m;
vm_object_t obj;
int iosize;
struct vnode *vp = bp->b_vp;
obj = vp->v_object;
#if defined(VFS_BIO_DEBUG)
if (vp->v_usecount == 0) {
panic("biodone: zero vnode ref count");
}
if (vp->v_object == NULL) {
panic("biodone: missing VM object");
}
if ((vp->v_flag & VOBJBUF) == 0) {
panic("biodone: vnode is not setup for merged cache");
}
#endif
if (vp->v_type == VBLK)
foff = (vm_ooffset_t) DEV_BSIZE * bp->b_lblkno;
else
foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno;
#if !defined(MAX_PERF)
if (!obj) {
panic("biodone: no object");
}
#endif
#if defined(VFS_BIO_DEBUG)
if (obj->paging_in_progress < bp->b_npages) {
printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
obj->paging_in_progress, bp->b_npages);
}
#endif
iosize = bp->b_bufsize;
for (i = 0; i < bp->b_npages; i++) {
int bogusflag = 0;
m = bp->b_pages[i];
if (m == bogus_page) {
bogusflag = 1;
m = vm_page_lookup(obj, OFF_TO_IDX(foff));
if (!m) {
#if defined(VFS_BIO_DEBUG)
printf("biodone: page disappeared\n");
#endif
--obj->paging_in_progress;
continue;
}
bp->b_pages[i] = m;
pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages);
}
#if defined(VFS_BIO_DEBUG)
if (OFF_TO_IDX(foff) != m->pindex) {
printf("biodone: foff(%d)/m->pindex(%d) mismatch\n", foff, m->pindex);
}
#endif
resid = IDX_TO_OFF(m->pindex + 1) - foff;
if (resid > iosize)
resid = iosize;
/*
* In the write case, the valid and clean bits are
* already changed correctly, so we only need to do this
* here in the read case.
*/
if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) {
vfs_page_set_valid(bp, foff, i, m);
}
/*
* when debugging new filesystems or buffer I/O methods, this
* is the most common error that pops up. if you see this, you
* have not set the page busy flag correctly!!!
*/
if (m->busy == 0) {
#if !defined(MAX_PERF)
printf("biodone: page busy < 0, "
"pindex: %d, foff: 0x(%x,%x), "
"resid: %d, index: %d\n",
(int) m->pindex, (int)(foff >> 32),
(int) foff & 0xffffffff, resid, i);
#endif
if (vp->v_type != VBLK)
#if !defined(MAX_PERF)
printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n",
bp->b_vp->v_mount->mnt_stat.f_iosize,
(int) bp->b_lblkno,
bp->b_flags, bp->b_npages);
else
printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n",
(int) bp->b_lblkno,
bp->b_flags, bp->b_npages);
printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n",
m->valid, m->dirty, m->wire_count);
#endif
panic("biodone: page busy < 0\n");
}
PAGE_BWAKEUP(m);
--obj->paging_in_progress;
foff += resid;
iosize -= resid;
}
if (obj &&
(obj->paging_in_progress == 0) &&
(obj->flags & OBJ_PIPWNT)) {
obj->flags &= ~OBJ_PIPWNT;
wakeup(obj);
}
}
/*
* For asynchronous completions, release the buffer now. The brelse
* checks for B_WANTED and will do the wakeup there if necessary - so
* no need to do a wakeup here in the async case.
*/
if (bp->b_flags & B_ASYNC) {
if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0)
brelse(bp);
else
bqrelse(bp);
} else {
bp->b_flags &= ~B_WANTED;
wakeup(bp);
}
splx(s);
}
static int
count_lock_queue()
{
int count;
struct buf *bp;
count = 0;
for (bp = TAILQ_FIRST(&bufqueues[QUEUE_LOCKED]);
bp != NULL;
bp = TAILQ_NEXT(bp, b_freelist))
count++;
return (count);
}
static int vfs_update_interval = 30;
static void
vfs_update()
{
while (1) {
tsleep(&vfs_update_wakeup, PUSER, "update",
hz * vfs_update_interval);
vfs_update_wakeup = 0;
sync(curproc, NULL);
}
}
static int
sysctl_kern_updateinterval SYSCTL_HANDLER_ARGS
{
int error = sysctl_handle_int(oidp,
oidp->oid_arg1, oidp->oid_arg2, req);
if (!error)
wakeup(&vfs_update_wakeup);
return error;
}
SYSCTL_PROC(_kern, KERN_UPDATEINTERVAL, update, CTLTYPE_INT|CTLFLAG_RW,
&vfs_update_interval, 0, sysctl_kern_updateinterval, "I", "");
/*
* This routine is called in lieu of iodone in the case of
* incomplete I/O. This keeps the busy status for pages
* consistant.
*/
void
vfs_unbusy_pages(struct buf * bp)
{
int i;
if (bp->b_flags & B_VMIO) {
struct vnode *vp = bp->b_vp;
vm_object_t obj = vp->v_object;
vm_ooffset_t foff;
foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno;
for (i = 0; i < bp->b_npages; i++) {
vm_page_t m = bp->b_pages[i];
if (m == bogus_page) {
m = vm_page_lookup(obj, OFF_TO_IDX(foff) + i);
#if !defined(MAX_PERF)
if (!m) {
panic("vfs_unbusy_pages: page missing\n");
}
#endif
bp->b_pages[i] = m;
pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages);
}
--obj->paging_in_progress;
PAGE_BWAKEUP(m);
}
if (obj->paging_in_progress == 0 &&
(obj->flags & OBJ_PIPWNT)) {
obj->flags &= ~OBJ_PIPWNT;
wakeup(obj);
}
}
}
/*
* Set NFS' b_validoff and b_validend fields from the valid bits
* of a page. If the consumer is not NFS, and the page is not
* valid for the entire range, clear the B_CACHE flag to force
* the consumer to re-read the page.
*/
static void
vfs_buf_set_valid(struct buf *bp,
vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
vm_page_t m)
{
if (bp->b_vp->v_tag == VT_NFS && bp->b_vp->v_type != VBLK) {
vm_offset_t svalid, evalid;
int validbits = m->valid;
/*
* This only bothers with the first valid range in the
* page.
*/
svalid = off;
while (validbits && !(validbits & 1)) {
svalid += DEV_BSIZE;
validbits >>= 1;
}
evalid = svalid;
while (validbits & 1) {
evalid += DEV_BSIZE;
validbits >>= 1;
}
/*
* Make sure this range is contiguous with the range
* built up from previous pages. If not, then we will
* just use the range from the previous pages.
*/
if (svalid == bp->b_validend) {
bp->b_validoff = min(bp->b_validoff, svalid);
bp->b_validend = max(bp->b_validend, evalid);
}
} else if (!vm_page_is_valid(m,
(vm_offset_t) ((foff + off) & PAGE_MASK),
size)) {
bp->b_flags &= ~B_CACHE;
}
}
/*
* Set the valid bits in a page, taking care of the b_validoff,
* b_validend fields which NFS uses to optimise small reads. Off is
* the offset within the file and pageno is the page index within the buf.
*/
static void
vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
{
struct vnode *vp = bp->b_vp;
vm_ooffset_t soff, eoff;
soff = off;
eoff = off + min(PAGE_SIZE, bp->b_bufsize);
vm_page_set_invalid(m,
(vm_offset_t) (soff & PAGE_MASK),
(vm_offset_t) (eoff - soff));
if (vp->v_tag == VT_NFS && vp->v_type != VBLK) {
vm_ooffset_t sv, ev;
off = off - pageno * PAGE_SIZE;
sv = off + ((bp->b_validoff + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1));
ev = off + ((bp->b_validend + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1));
soff = max(sv, soff);
eoff = min(ev, eoff);
}
if (eoff > soff)
vm_page_set_validclean(m,
(vm_offset_t) (soff & PAGE_MASK),
(vm_offset_t) (eoff - soff));
}
/*
* This routine is called before a device strategy routine.
* It is used to tell the VM system that paging I/O is in
* progress, and treat the pages associated with the buffer
* almost as being PG_BUSY. Also the object paging_in_progress
* flag is handled to make sure that the object doesn't become
* inconsistant.
*/
void
vfs_busy_pages(struct buf * bp, int clear_modify)
{
int i,s;
if (bp->b_flags & B_VMIO) {
struct vnode *vp = bp->b_vp;
vm_object_t obj = vp->v_object;
vm_ooffset_t foff;
if (vp->v_type == VBLK)
foff = (vm_ooffset_t) DEV_BSIZE * bp->b_lblkno;
else
foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno;
vfs_setdirty(bp);
retry:
for (i = 0; i < bp->b_npages; i++) {
vm_page_t m = bp->b_pages[i];
if (vm_page_sleep(m, "vbpage", NULL))
goto retry;
}
for (i = 0; i < bp->b_npages; i++, foff += PAGE_SIZE) {
vm_page_t m = bp->b_pages[i];
if ((bp->b_flags & B_CLUSTER) == 0) {
obj->paging_in_progress++;
m->busy++;
}
vm_page_protect(m, VM_PROT_NONE);
if (clear_modify)
vfs_page_set_valid(bp, foff, i, m);
else if (bp->b_bcount >= PAGE_SIZE) {
if (m->valid && (bp->b_flags & B_CACHE) == 0) {
bp->b_pages[i] = bogus_page;
pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages);
}
}
}
}
}
/*
* Tell the VM system that the pages associated with this buffer
* are clean. This is used for delayed writes where the data is
* going to go to disk eventually without additional VM intevention.
*/
void
vfs_clean_pages(struct buf * bp)
{
int i;
if (bp->b_flags & B_VMIO) {
struct vnode *vp = bp->b_vp;
vm_ooffset_t foff;
if (vp->v_type == VBLK)
foff = (vm_ooffset_t) DEV_BSIZE * bp->b_lblkno;
else
foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno;
for (i = 0; i < bp->b_npages; i++, foff += PAGE_SIZE) {
vm_page_t m = bp->b_pages[i];
vfs_page_set_valid(bp, foff, i, m);
}
}
}
void
vfs_bio_clrbuf(struct buf *bp) {
int i;
if( bp->b_flags & B_VMIO) {
if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE)) {
int mask;
mask = 0;
for(i=0;i<bp->b_bufsize;i+=DEV_BSIZE)
mask |= (1 << (i/DEV_BSIZE));
if( bp->b_pages[0]->valid != mask) {
bzero(bp->b_data, bp->b_bufsize);
}
bp->b_pages[0]->valid = mask;
bp->b_resid = 0;
return;
}
for(i=0;i<bp->b_npages;i++) {
if( bp->b_pages[i]->valid == VM_PAGE_BITS_ALL)
continue;
if( bp->b_pages[i]->valid == 0) {
if ((bp->b_pages[i]->flags & PG_ZERO) == 0) {
bzero(bp->b_data + (i << PAGE_SHIFT), PAGE_SIZE);
}
} else {
int j;
for(j=0;j<PAGE_SIZE/DEV_BSIZE;j++) {
if( (bp->b_pages[i]->valid & (1<<j)) == 0)
bzero(bp->b_data + (i << PAGE_SHIFT) + j * DEV_BSIZE, DEV_BSIZE);
}
}
/* bp->b_pages[i]->valid = VM_PAGE_BITS_ALL; */
}
bp->b_resid = 0;
} else {
clrbuf(bp);
}
}
/*
* vm_hold_load_pages and vm_hold_unload pages get pages into
* a buffers address space. The pages are anonymous and are
* not associated with a file object.
*/
void
vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to)
{
vm_offset_t pg;
vm_page_t p;
int index;
to = round_page(to);
from = round_page(from);
index = (from - trunc_page(bp->b_data)) >> PAGE_SHIFT;
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
tryagain:
p = vm_page_alloc(kernel_object,
((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
VM_ALLOC_NORMAL);
if (!p) {
vm_pageout_deficit += (to - from) >> PAGE_SHIFT;
VM_WAIT;
goto tryagain;
}
vm_page_wire(p);
p->valid = VM_PAGE_BITS_ALL;
pmap_kenter(pg, VM_PAGE_TO_PHYS(p));
bp->b_pages[index] = p;
PAGE_WAKEUP(p);
}
bp->b_npages = index;
}
void
vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to)
{
vm_offset_t pg;
vm_page_t p;
int index, newnpages;
from = round_page(from);
to = round_page(to);
newnpages = index = (from - trunc_page(bp->b_data)) >> PAGE_SHIFT;
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
p = bp->b_pages[index];
if (p && (index < bp->b_npages)) {
#if !defined(MAX_PERF)
if (p->busy) {
printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n",
bp->b_blkno, bp->b_lblkno);
}
#endif
bp->b_pages[index] = NULL;
pmap_kremove(pg);
p->flags |= PG_BUSY;
vm_page_unwire(p);
vm_page_free(p);
}
}
bp->b_npages = newnpages;
}
#include "opt_ddb.h"
#ifdef DDB
#include <ddb/ddb.h>
DB_SHOW_COMMAND(buffer, db_show_buffer)
{
/* get args */
struct buf *bp = (struct buf *)addr;
if (!have_addr) {
db_printf("usage: show buffer <addr>\n");
return;
}
db_printf("b_proc = %p,\nb_flags = 0x%b\n", (void *)bp->b_proc,
bp->b_flags, "\20\40bounce\37cluster\36vmio\35ram\34ordered"
"\33paging\32xxx\31writeinprog\30wanted\27relbuf\26tape"
"\25read\24raw\23phys\22clusterok\21malloc\20nocache"
"\17locked\16inval\15gathered\14error\13eintr\12done\11dirty"
"\10delwri\7call\6cache\5busy\4bad\3async\2needcommit\1age");
db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, "
"b_resid = %ld\nb_dev = 0x%x, b_data = %p, "
"b_blkno = %d, b_pblkno = %d\n",
bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
bp->b_dev, bp->b_data, bp->b_blkno, bp->b_pblkno);
if (bp->b_npages) {
int i;
db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
for (i = 0; i < bp->b_npages; i++) {
vm_page_t m;
m = bp->b_pages[i];
db_printf("(0x%x, 0x%x, 0x%x)", m->object, m->pindex,
VM_PAGE_TO_PHYS(m));
if ((i + 1) < bp->b_npages)
db_printf(",");
}
db_printf("\n");
}
}
#endif /* DDB */
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