mirror/freebsd
1
0
Fork 0
mirror of https://git.FreeBSD.org/src.git synced 2024-12-23 11:18:54 +00:00
Code Issues Releases Activity
fcdfed00d5
freebsd/sys/kern/vfs_bio.c
David Greenman 4f699173cb Closed a very narrow and rare race condition that involved net interrupts, 
bio interrupts, and a truncated file that along with the precise alignment
of the planets could result in a page being freed multiple times or a
just-freed page being put onto the inactive queue.
1998-11-18 09:00:47 +00:00

2397 lines
57 KiB
C
Raw Blame History

/*
* 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 1.184 1998/10/31 15:31:22 peter 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.
*/
#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 <miscfs/specfs/specdev.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");
struct bio_ops bioops; /* I/O operation notification */
#if 0 /* replaced bu sched_sync */
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)
#endif
struct buf *buf; /* buffer header pool */
struct swqueue bswlist;
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_xflags = 0;
LIST_INIT(&bp->b_dep);
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(vp, 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(vp, 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(vp, 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, s;
struct vnode *vp;
struct mount *mp;
if (bp->b_flags & B_INVAL) {
brelse(bp);
return (0);
}
oldflags = bp->b_flags;
#if !defined(MAX_PERF)
if ((bp->b_flags & B_BUSY) == 0)
panic("bwrite: buffer is not busy???");
#endif
bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI);
bp->b_flags |= B_WRITEINPROG;
s = splbio();
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++;
splx(s);
VOP_STRATEGY(bp->b_vp, bp);
/*
* Collect statistics on synchronous and asynchronous writes.
* Writes to block devices are charged to their associated
* filesystem (if any).
*/
if ((vp = bp->b_vp) != NULL) {
if (vp->v_type == VBLK)
mp = vp->v_specmountpoint;
else
mp = vp->v_mount;
if (mp != NULL)
if ((oldflags & B_ASYNC) == 0)
mp->mnt_stat.f_syncwrites++;
else
mp->mnt_stat.f_asyncwrites++;
}
if ((oldflags & B_ASYNC) == 0) {
int rtval = biowait(bp);
brelse(bp);
return (rtval);
}
return (0);
}
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)
{
struct vnode *vp;
#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;
}
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);
/*
* XXX The soft dependency code is not prepared to
* have I/O done when a bdwrite is requested. For
* now we just let the write be delayed if it is
* requested by the soft dependency code.
*/
if ((vp = bp->b_vp) &&
(vp->v_type == VBLK && vp->v_specmountpoint &&
(vp->v_specmountpoint->mnt_flag & MNT_SOFTDEP)) ||
(vp->v_mount && (vp->v_mount->mnt_flag & MNT_SOFTDEP)))
return;
if (numdirtybuffers >= hidirtybuffers)
flushdirtybuffers(0, 0);
return;
}
/*
* Same as first half of bdwrite, mark buffer dirty, but do not release it.
* Check how this compares with vfs_setdirty(); XXX [JRE]
*/
void
bdirty(bp)
struct buf *bp;
{
bp->b_flags &= ~(B_READ|B_RELBUF); /* XXX ??? check this */
if ((bp->b_flags & B_DELWRI) == 0) {
bp->b_flags |= B_DONE | B_DELWRI; /* why done? XXX JRE */
reassignbuf(bp, bp->b_vp);
++numdirtybuffers;
}
}
/*
* 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, and flag it so that the device will write
* it in the order it was queued. The buffer is released when the output
* completes.
*/
int
bowrite(struct buf * bp)
{
bp->b_flags |= B_ORDERED|B_ASYNC;
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 | B_FREEBUF)) ||
(bp->b_bufsize <= 0)) {
bp->b_flags |= B_INVAL;
if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate)
(*bioops.io_deallocate)(bp);
if (bp->b_flags & B_DELWRI)
--numdirtybuffers;
bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF);
if ((bp->b_flags & B_VMIO) == 0) {
if (bp->b_bufsize)
allocbuf(bp, 0);
if (bp->b_vp)
brelvp(bp);
}
}
/*
* We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
* is called with B_DELWRI set, the underlying pages may wind up
* getting freed causing a previous write (bdwrite()) to get 'lost'
* because pages associated with a B_DELWRI bp are marked clean.
*
* We still allow the B_INVAL case to call vfs_vmio_release(), even
* if B_DELWRI is set.
*/
if (bp->b_flags & B_DELWRI)
bp->b_flags &= ~B_RELBUF;
/*
* 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;
vp = bp->b_vp;
resid = bp->b_bufsize;
foff = bp->b_offset;
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
vm_page_flag_clear(m, PG_ZERO);
if (m == bogus_page) {
obj = (vm_object_t) vp->v_object;
poff = OFF_TO_IDX(bp->b_offset);
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((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
}
}
if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
int poffset = foff & PAGE_MASK;
int presid = resid > (PAGE_SIZE - poffset) ?
(PAGE_SIZE - poffset) : resid;
vm_page_set_invalid(m, poffset, presid);
}
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;
/* 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;
/* 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, s;
vm_page_t m;
s = splvm();
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
bp->b_pages[i] = NULL;
/*
* In order to keep page LRU ordering consistent, put
* everything on the inactive queue.
*/
vm_page_unwire(m, 0);
/*
* 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) {
vm_page_flag_clear(m, PG_ZERO);
/*
* Might as well free the page if we can and it has
* no valid data.
*/
if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) {
vm_page_busy(m);
vm_page_protect(m, VM_PROT_NONE);
vm_page_free(m);
}
}
}
splx(s);
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);
bp->b_flags |= B_BUSY | B_ASYNC;
splx(s);
/*
* default (old) behavior, writing out only one block
*/
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 + 4) | 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) {
if (writerecursion > 5) {
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 {
bremfree(bp);
bp->b_flags |= B_BUSY | B_AGE | B_ASYNC;
nbyteswritten += bp->b_bufsize;
++writerecursion;
VOP_BWRITE(bp);
--writerecursion;
if (!slpflag && !slptimeo) {
return (0);
}
goto start;
}
} 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:
/* 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;
}
if (LIST_FIRST(&bp->b_dep) != NULL &&
bioops.io_deallocate)
(*bioops.io_deallocate)(bp);
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_offset = NOOFFSET;
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;
/* Here, not kern_physio.c, is where this should be done*/
LIST_INIT(&bp->b_dep);
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 + 4)|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 + 4)|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) & PAGE_MASK), 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_flag_clear(bp->b_pages[i], PG_ZERO);
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 checksize;
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))) {
if (bp->b_flags & B_BUSY) {
bp->b_flags |= B_WANTED;
if (bp->b_usecount < BUF_MAXUSE)
++bp->b_usecount;
if (!tsleep(bp,
(PRIBIO + 4) | 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 (if needed) and re-constitute it.
*/
if (bp->b_bcount != size) {
if ((bp->b_flags & B_VMIO) && (size <= bp->b_kvasize)) {
allocbuf(bp, size);
} else {
if (bp->b_flags & B_DELWRI) {
bp->b_flags |= B_NOCACHE;
VOP_BWRITE(bp);
} else {
if ((bp->b_flags & B_VMIO) &&
(LIST_FIRST(&bp->b_dep) == NULL)) {
bp->b_flags |= B_RELBUF;
brelse(bp);
} else {
bp->b_flags |= B_NOCACHE;
VOP_BWRITE(bp);
}
}
goto loop;
}
}
#ifdef DIAGNOSTIC
if (bp->b_offset == NOOFFSET)
panic("getblk: no buffer offset");
#endif
/*
* Check that the constituted buffer really deserves for the
* B_CACHE bit to be set. B_VMIO type buffers might not
* contain fully valid pages. Normal (old-style) buffers
* should be fully valid.
*/
if (bp->b_flags & B_VMIO) {
checksize = bp->b_bufsize;
for (i = 0; i < bp->b_npages; i++) {
int resid;
int poffset;
poffset = bp->b_offset & PAGE_MASK;
resid = (checksize > (PAGE_SIZE - poffset)) ?
(PAGE_SIZE - poffset) : checksize;
if (!vm_page_is_valid(bp->b_pages[i], poffset, resid)) {
bp->b_flags &= ~(B_CACHE | B_DONE);
break;
}
checksize -= resid;
}
}
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) != LK_EXCLUSIVE && 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;
if (vp->v_type != VBLK)
bp->b_offset = (off_t) blkno * maxsize;
else
bp->b_offset = (off_t) blkno * DEV_BSIZE;
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);
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; /* b_dep cleared by getnewbuf() */
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 its 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, 0);
}
pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)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 = bp->b_offset;
#ifdef DIAGNOSTIC
if (bp->b_offset == NOOFFSET)
panic("allocbuf: no buffer offset");
#endif
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);
vm_page_flag_clear(m, PG_BUSY);
bp->b_flags &= ~B_CACHE;
} else if (m->flags & PG_BUSY) {
s = splvm();
if (m->flags & PG_BUSY) {
vm_page_flag_set(m, 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_flag_clear(m, PG_ZERO);
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((vm_offset_t)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, PRIBIO, "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_FREEBUF) {
brelse(bp);
splx(s);
return;
}
if ((bp->b_flags & B_READ) == 0) {
vwakeup(bp);
}
/* 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 (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete)
(*bioops.io_complete)(bp);
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
foff = bp->b_offset;
#ifdef DIAGNOSTIC
if (bp->b_offset == NOOFFSET)
panic("biodone: no buffer offset");
#endif
#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
vm_object_pip_subtract(obj, 1);
continue;
}
bp->b_pages[i] = m;
pmap_qenter(trunc_page((vm_offset_t)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);
}
vm_page_flag_clear(m, PG_ZERO);
/*
* 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");
}
vm_page_io_finish(m);
vm_object_pip_subtract(obj, 1);
foff += resid;
iosize -= resid;
}
if (obj &&
(obj->paging_in_progress == 0) &&
(obj->flags & OBJ_PIPWNT)) {
vm_object_clear_flag(obj, 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);
}
#if 0 /* not with kirks code */
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", "");
#endif
/*
* 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;
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(bp->b_offset) + i);
#if !defined(MAX_PERF)
if (!m) {
panic("vfs_unbusy_pages: page missing\n");
}
#endif
bp->b_pages[i] = m;
pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
}
vm_object_pip_subtract(obj, 1);
vm_page_flag_clear(m, PG_ZERO);
vm_page_io_finish(m);
}
if (obj->paging_in_progress == 0 &&
(obj->flags & OBJ_PIPWNT)) {
vm_object_clear_flag(obj, 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);
if (vp->v_tag == VT_NFS && vp->v_type != VBLK) {
vm_ooffset_t sv, ev;
vm_page_set_invalid(m,
(vm_offset_t) (soff & PAGE_MASK),
(vm_offset_t) (eoff - soff));
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 = qmax(sv, soff);
eoff = qmin(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;
if (bp->b_flags & B_VMIO) {
struct vnode *vp = bp->b_vp;
vm_object_t obj = vp->v_object;
vm_ooffset_t foff;
foff = bp->b_offset;
#ifdef DIAGNOSTIC
if (bp->b_offset == NOOFFSET)
panic("vfs_busy_pages: no buffer offset");
#endif
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];
vm_page_flag_clear(m, PG_ZERO);
if ((bp->b_flags & B_CLUSTER) == 0) {
vm_object_pip_add(obj, 1);
vm_page_io_start(m);
}
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((vm_offset_t)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) {
vm_ooffset_t foff;
foff = bp->b_offset;
#ifdef DIAGNOSTIC
if (bp->b_offset == NOOFFSET)
panic("vfs_clean_pages: no buffer offset");
#endif
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 | B_MALLOC)) == 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]->flags & PG_ZERO) == 0) &&
(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]->flags & PG_ZERO) == 0) &&
(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;
vm_page_flag_clear(bp->b_pages[i], PG_ZERO);
}
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((vm_offset_t)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;
vm_page_flag_clear(p, PG_ZERO);
pmap_kenter(pg, VM_PAGE_TO_PHYS(p));
bp->b_pages[index] = p;
vm_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((vm_offset_t)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);
vm_page_busy(p);
vm_page_unwire(p, 0);
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,
(u_int)bp->b_flags, PRINT_BUF_FLAGS);
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("(%p, 0x%lx, 0x%lx)", (void *)m->object,
(u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
if ((i + 1) < bp->b_npages)
db_printf(",");
}
db_printf("\n");
}
}
#endif /* DDB */
Reference in New Issue View Git Blame Copy Permalink