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freebsd-nq/sys/kern/vfs_bio.c
David Greenman 7c818168d5 Fixed a major bug that caused various pmap related panics, hangs, and reboots. 
The i386 pmap module uses a special area of kernel virtual memory for mapping
of page tables pages when it needs to modify another process's virtual
address space. It's called the 'alternate page table map'. There is only one
of them and it's expected that only one process will be using it at once and
that the operation is atomic.
When the merged VM/buffer cache was implemented over a year ago, it became
necessary to rundown VM pages at I/O completion. The unfortunate and
unforeseen side effect of this is that pmap functions are now called at bio
interrupt time. If there happend to be a process using the alternate page
table map when this I/O completion occurred, it was possible for a different
process's address space to be switched into the alternate page table map -
leaving the current pmap process with the wrong address space mapped when
the interrupt completed. This resulted in BAD things happening like pages
being mapped or removed from the wrong address space, etc.. Since a very
common case of a process modifying another process's address space is during
fork when the kernel stack is inserted, one of the most common manifestations
of this bug was the kernel stack not being mapped properly, resulting in a
silent hang or reboot. This made it VERY difficult to troubleshoot this bug
(I've been trying to figure out the cause of this for >6 months). Fortunately,
the set of conditions that must be true before this problem occurs is
sufficiently rare enough that most people never saw the bug occur. As I/O
rates increase, however, so does the frequency of the crashes. This problem
used to kill wcarchive about every 10 days, but in more recent times when
the traffic exceeded >100GB/day, the machine could barely manage 6 hours of
uptime.
The fix is to make certain that no process has the pages mapped that are
involved in the I/O, before the I/O is started. The pages are made busy, so
no process will be able to map them, either, until the I/O has finished.
This side-steps the issue by still allowing the pmap functions to be called
at interrupt time, but also assuring that the alternate page table map won't
be switched.
Unfortunately, this appears to not be the only cause of this problem. :-(

Reviewed by:	dyson
1996-06-30 05:17:08 +00:00

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/*
* Copyright (c) 1994 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. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Absolutely no warranty of function or purpose is made by the author
* John S. Dyson.
* 4. This work was done expressly for inclusion into FreeBSD. Other use
* is allowed if this notation is included.
* 5. Modifications may be freely made to this file if the above conditions
* are met.
*
* $Id: vfs_bio.c,v 1.93 1996/06/14 11:01:27 asami 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 <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 <sys/buf.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/resourcevar.h>
#include <sys/proc.h>
#include <miscfs/specfs/specdev.h>
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;
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_clean_pages(struct buf * bp);
static void vfs_setdirty(struct buf *bp);
static void vfs_vmio_release(struct buf *bp);
int needsbuffer;
/*
* Internal update daemon, process 3
* The variable vfs_update_wakeup allows for internal syncs.
*/
int vfs_update_wakeup;
/*
* buffers base kva
*/
caddr_t buffers_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;
static struct bufhashhdr bufhashtbl[BUFHSZ], invalhash;
static struct bqueues bufqueues[BUFFER_QUEUES];
extern int vm_swap_size;
#define BUF_MAXUSE 8
/*
* 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]);
buffers_kva = (caddr_t) kmem_alloc_pageable(buffer_map, MAXBSIZE * nbuf);
/* 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_data = buffers_kva + i * MAXBSIZE;
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 = 2 * (nbuf + 8) * PAGE_SIZE;
/*
* 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;
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);
}
/*
* remove the buffer from the appropriate free list
*/
void
bremfree(struct buf * bp)
{
int s = splbio();
if (bp->b_qindex != QUEUE_NONE) {
TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
bp->b_qindex = QUEUE_NONE;
} else {
panic("bremfree: removing a buffer when not on a queue");
}
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 (!(bp->b_flags & B_BUSY))
panic("bwrite: buffer is not busy???");
bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI);
bp->b_flags |= B_WRITEINPROG;
if ((oldflags & (B_ASYNC|B_DELWRI)) == (B_ASYNC|B_DELWRI)) {
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);
}
int
vn_bwrite(ap)
struct vop_bwrite_args *ap;
{
return (bwrite(ap->a_bp));
}
/*
* Delayed write. (Buffer is marked dirty).
*/
void
bdwrite(struct buf * bp)
{
if ((bp->b_flags & B_BUSY) == 0) {
panic("bdwrite: buffer is not busy");
}
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);
}
/*
* 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);
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);
}
/*
* Release a buffer.
*/
void
brelse(struct buf * bp)
{
int s;
if (bp->b_flags & B_CLUSTER) {
relpbuf(bp);
return;
}
/* anyone need a "free" block? */
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;
bp->b_flags &= ~(B_DELWRI | B_CACHE);
if (((bp->b_flags & B_VMIO) == 0) && bp->b_vp) {
if (bp->b_bufsize)
allocbuf(bp, 0);
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 (bp->b_flags & B_VMIO) {
vm_ooffset_t foff;
vm_object_t obj;
int i, resid;
vm_page_t m;
struct vnode *vp;
int iototal = bp->b_bufsize;
vp = bp->b_vp;
if (!vp)
panic("brelse: missing vp");
if (bp->b_npages) {
vm_pindex_t poff;
obj = (vm_object_t) vp->v_object;
if (vp->v_type == VBLK)
foff = ((vm_ooffset_t) bp->b_lblkno) << DEV_BSHIFT;
else
foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno;
poff = OFF_TO_IDX(foff);
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if (m == bogus_page) {
m = vm_page_lookup(obj, poff + i);
if (!m) {
panic("brelse: page missing\n");
}
bp->b_pages[i] = m;
pmap_qenter(trunc_page(bp->b_data),
bp->b_pages, bp->b_npages);
}
resid = IDX_TO_OFF(m->pindex+1) - foff;
if (resid > iototal)
resid = iototal;
if (resid > 0) {
/*
* Don't invalidate the page if the local machine has already
* modified it. This is the lesser of two evils, and should
* be fixed.
*/
if (bp->b_flags & (B_NOCACHE | B_ERROR)) {
vm_page_test_dirty(m);
if (m->dirty == 0) {
vm_page_set_invalid(m, (vm_offset_t) foff, resid);
if (m->valid == 0)
vm_page_protect(m, VM_PROT_NONE);
}
}
if (resid >= PAGE_SIZE) {
if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) {
bp->b_flags |= B_INVAL;
}
} else {
if (!vm_page_is_valid(m,
(((vm_offset_t) bp->b_data) & PAGE_MASK), resid)) {
bp->b_flags |= B_INVAL;
}
}
}
foff += resid;
iototal -= resid;
}
}
if (bp->b_flags & (B_INVAL | B_RELBUF))
vfs_vmio_release(bp);
}
if (bp->b_qindex != QUEUE_NONE)
panic("brelse: free buffer onto another queue???");
/* enqueue */
/* buffers with no memory */
if (bp->b_bufsize == 0) {
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;
if (needsbuffer) {
wakeup(&needsbuffer);
needsbuffer=0;
}
/* buffers with junk contents */
} else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) {
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;
if (needsbuffer) {
wakeup(&needsbuffer);
needsbuffer=0;
}
/* 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);
if (needsbuffer) {
wakeup(&needsbuffer);
needsbuffer=0;
}
/* buffers with valid and quite potentially reuseable contents */
} else {
bp->b_qindex = QUEUE_LRU;
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
if (needsbuffer) {
wakeup(&needsbuffer);
needsbuffer=0;
}
}
/* unlock */
bp->b_flags &= ~(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 (bp->b_qindex != QUEUE_NONE)
panic("bqrelse: free buffer onto another queue???");
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 (needsbuffer) {
wakeup(&needsbuffer);
needsbuffer=0;
}
}
/* unlock */
bp->b_flags &= ~(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;
if (m->flags & PG_WANTED) {
m->flags &= ~PG_WANTED;
wakeup(m);
}
vm_page_unwire(m);
if (m->wire_count == 0 && (m->flags & PG_BUSY) == 0) {
if (m->valid) {
if(m->dirty == 0)
vm_page_test_dirty(m);
/*
* this keeps pressure off of the process memory
*/
if ((vm_swap_size == 0) ||
(cnt.v_free_count < cnt.v_free_min)) {
if ((m->dirty == 0) &&
(m->hold_count == 0) &&
(m->flags & PG_BUSY) == 0 &&
(m->busy == 0))
vm_page_cache(m);
else
vm_page_deactivate(m);
}
} else if ((m->hold_count == 0) &&
((m->flags & PG_BUSY) == 0) &&
(m->busy == 0)) {
vm_page_protect(m, VM_PROT_NONE);
vm_page_free(m);
}
}
}
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.
*/
__inline 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;
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) {
int size;
int maxcl;
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(int slpflag, int slptimeo, int doingvmio)
{
struct buf *bp;
int nbyteswritten = 0;
start:
if (bufspace >= maxbufspace)
goto trytofreespace;
/* can we constitute a new buffer? */
if ((bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]))) {
if (bp->b_qindex != QUEUE_EMPTY)
panic("getnewbuf: inconsistent EMPTY queue, qindex=%d",
bp->b_qindex);
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 (bp->b_qindex != QUEUE_AGE)
panic("getnewbuf: inconsistent AGE queue, qindex=%d",
bp->b_qindex);
} else if ((bp = TAILQ_FIRST(&bufqueues[QUEUE_LRU]))) {
if (bp->b_qindex != QUEUE_LRU)
panic("getnewbuf: inconsistent LRU queue, qindex=%d",
bp->b_qindex);
}
if (!bp) {
/* wait for a free buffer of any kind */
needsbuffer = 1;
tsleep(&needsbuffer,
(PRIBIO + 1) | slpflag, "newbuf", slptimeo);
return (0);
}
/*
* 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) {
nbyteswritten += vfs_bio_awrite(bp);
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)
vfs_vmio_release(bp);
if (bp->b_vp)
brelvp(bp);
fillbuf:
/* 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_data = buffers_kva + (bp - buf) * MAXBSIZE;
bp->b_dirtyoff = bp->b_dirtyend = 0;
bp->b_validoff = bp->b_validend = 0;
bp->b_usecount = 2;
if (bufspace >= maxbufspace + nbyteswritten) {
bp->b_flags |= B_INVAL;
brelse(bp);
goto trytofreespace;
}
return (bp);
}
/*
* 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 & VVMIO) == 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 s;
struct bufhashhdr *bh;
s = splbio();
loop:
if ((bp = gbincore(vp, blkno))) {
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))
goto loop;
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) {
if (bp->b_flags & B_VMIO) {
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;
int doingvmio;
if ((obj = vp->v_object) && (vp->v_flag & VVMIO)) {
doingvmio = 1;
} else {
doingvmio = 0;
}
if ((bp = getnewbuf(slpflag, slptimeo, doingvmio)) == 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 (doingvmio) {
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;
}
splx(s);
allocbuf(bp, size);
#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, 0, 0)) == 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 (!(bp->b_flags & B_BUSY))
panic("allocbuf: buffer not busy");
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 (bp->b_flags & B_MALLOC)
newbsize = mbsize;
else
newbsize = round_page(size);
if (newbsize < bp->b_bufsize) {
/*
* malloced buffers are not shrunk
*/
if (bp->b_flags & B_MALLOC) {
if (newbsize) {
bp->b_bcount = size;
} else {
free(bp->b_data, M_TEMP);
bufspace -= bp->b_bufsize;
bufmallocspace -= bp->b_bufsize;
bp->b_data = (caddr_t) buffers_kva + (bp - buf) * MAXBSIZE;
bp->b_bufsize = 0;
bp->b_bcount = 0;
bp->b_flags &= ~B_MALLOC;
}
return 1;
}
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) {
/*
* 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_TEMP, M_WAITOK);
bp->b_bufsize = mbsize;
bp->b_bcount = size;
bp->b_flags |= B_MALLOC;
bufspace += mbsize;
bufmallocspace += mbsize;
return 1;
}
origbuf = NULL;
origbufsize = 0;
/*
* 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 = (caddr_t) buffers_kva + (bp - buf) * MAXBSIZE;
bufspace -= bp->b_bufsize;
bufmallocspace -= bp->b_bufsize;
bp->b_bufsize = 0;
bp->b_flags &= ~B_MALLOC;
newbsize = round_page(newbsize);
}
vm_hold_load_pages(
bp,
(vm_offset_t) bp->b_data + bp->b_bufsize,
(vm_offset_t) bp->b_data + newbsize);
if (origbuf) {
bcopy(origbuf, bp->b_data, origbufsize);
free(origbuf, M_TEMP);
}
}
} else {
vm_page_t m;
int desiredpages;
newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
desiredpages = (round_page(newbsize) >> PAGE_SHIFT);
if (bp->b_flags & B_MALLOC)
panic("allocbuf: VMIO buffer can't be malloced");
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];
s = splhigh();
while ((m->flags & PG_BUSY) || (m->busy != 0)) {
m->flags |= PG_WANTED;
tsleep(m, PVM, "biodep", 0);
}
splx(s);
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;
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;
doretry:
curbpnpages = bp->b_npages;
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) &&
!vm_page_is_valid(m,
(vm_offset_t) ((toff + off) & PAGE_MASK),
bytesinpage)) {
bp->b_flags &= ~B_CACHE;
}
continue;
}
m = vm_page_lookup(obj, objoff);
if (!m) {
m = vm_page_alloc(obj, objoff, VM_ALLOC_NORMAL);
if (!m) {
VM_WAIT;
goto doretry;
}
/*
* Normally it is unwise to clear PG_BUSY without
* PAGE_WAKEUP -- but it is okay here, as there is
* no chance for blocking between here and vm_page_alloc
*/
m->flags &= ~PG_BUSY;
vm_page_wire(m);
bp->b_flags &= ~B_CACHE;
} else if (m->flags & PG_BUSY) {
s = splhigh();
m->flags |= PG_WANTED;
tsleep(m, PVM, "pgtblk", 0);
splx(s);
goto doretry;
} else {
if ((curproc != pageproc) &&
(m->queue == 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) &&
!vm_page_is_valid(m,
(vm_offset_t) ((toff + off) & PAGE_MASK),
bytesinpage)) {
bp->b_flags &= ~B_CACHE;
}
vm_page_wire(m);
}
bp->b_pages[pageindex] = m;
curbpnpages = pageindex + 1;
}
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 += 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)
tsleep(bp, PRIBIO, "biowait", 0);
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 (!(bp->b_flags & B_BUSY))
panic("biodone: buffer not busy");
if (bp->b_flags & B_DONE) {
splx(s);
printf("biodone: buffer already done\n");
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;
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;
obj = vp->v_object;
if (!obj) {
panic("biodone: no object");
}
#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) {
vm_page_set_validclean(m,
(vm_offset_t) (foff & PAGE_MASK), resid);
}
/*
* 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) {
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);
if (vp->v_type != VBLK)
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);
panic("biodone: page busy < 0\n");
}
--m->busy;
if ((m->busy == 0) && (m->flags & PG_WANTED)) {
m->flags &= ~PG_WANTED;
wakeup(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 {
wakeup(bp);
}
splx(s);
}
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);
}
int vfs_update_interval = 30;
static void
vfs_update()
{
(void) spl0(); /* XXX redundant? wrong place? */
while (1) {
tsleep(&vfs_update_wakeup, PUSER, "update",
hz * vfs_update_interval);
vfs_update_wakeup = 0;
sync(curproc, NULL, 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 (!m) {
panic("vfs_unbusy_pages: page missing\n");
}
bp->b_pages[i] = m;
pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages);
}
--obj->paging_in_progress;
--m->busy;
if ((m->busy == 0) && (m->flags & PG_WANTED)) {
m->flags &= ~PG_WANTED;
wakeup(m);
}
}
if (obj->paging_in_progress == 0 &&
(obj->flags & OBJ_PIPWNT)) {
obj->flags &= ~OBJ_PIPWNT;
wakeup(obj);
}
}
}
/*
* 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;
if (bp->b_flags & B_VMIO) {
vm_object_t obj = bp->b_vp->v_object;
vm_ooffset_t foff;
int iocount = bp->b_bufsize;
if (bp->b_vp->v_type == VBLK)
foff = (vm_ooffset_t) DEV_BSIZE * bp->b_lblkno;
else
foff = (vm_ooffset_t) bp->b_vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno;
vfs_setdirty(bp);
for (i = 0; i < bp->b_npages; i++) {
vm_page_t m = bp->b_pages[i];
int resid = IDX_TO_OFF(m->pindex + 1) - foff;
if (resid > iocount)
resid = iocount;
if ((bp->b_flags & B_CLUSTER) == 0) {
obj->paging_in_progress++;
m->busy++;
}
vm_page_protect(m, VM_PROT_NONE);
if (clear_modify) {
vm_page_set_validclean(m,
(vm_offset_t) (foff & PAGE_MASK), resid);
} 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);
}
}
foff += resid;
iocount -= resid;
}
}
}
/*
* 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) {
vm_ooffset_t foff;
int iocount = bp->b_bufsize;
if (bp->b_vp->v_type == VBLK)
foff = (vm_ooffset_t) DEV_BSIZE * bp->b_lblkno;
else
foff = (vm_ooffset_t) bp->b_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];
int resid = IDX_TO_OFF(m->pindex + 1) - foff;
if (resid > iocount)
resid = iocount;
if (resid > 0) {
vm_page_set_validclean(m,
((vm_offset_t) foff & PAGE_MASK), resid);
}
foff += resid;
iocount -= resid;
}
}
}
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_WAIT;
goto tryagain;
}
vm_page_wire(p);
pmap_kenter(pg, VM_PAGE_TO_PHYS(p));
bp->b_pages[index] = p;
PAGE_WAKEUP(p);
}
bp->b_npages = to >> PAGE_SHIFT;
}
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;
from = round_page(from);
to = round_page(to);
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 (p->busy) {
printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n",
bp->b_blkno, bp->b_lblkno);
}
bp->b_pages[index] = NULL;
pmap_kremove(pg);
vm_page_unwire(p);
vm_page_free(p);
}
}
bp->b_npages = from >> PAGE_SHIFT;
}
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