projects / unix-history / blob
? search:
summary | tags | clone url | shortlog | log | commit | commitdiff | tree
blame | history | raw | HEAD
make bio and disk drivers not do spl0 so can call from panic without trap 2's
[unix-history] / usr / src / sys / kern / kern_physio.c
/* kern_physio.c 4.25 82/01/17 */
#include "../h/param.h"
#include "../h/systm.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/buf.h"
#include "../h/conf.h"
#include "../h/proc.h"
#include "../h/seg.h"
#include "../h/pte.h"
#include "../h/vm.h"
#include "../h/trace.h"
/*
* The following several routines allocate and free
* buffers with various side effects. In general the
* arguments to an allocate routine are a device and
* a block number, and the value is a pointer to
* to the buffer header; the buffer is marked "busy"
* so that no one else can touch it. If the block was
* already in core, no I/O need be done; if it is
* already busy, the process waits until it becomes free.
* The following routines allocate a buffer:
* getblk
* bread
* breada
* baddr (if it is incore)
* Eventually the buffer must be released, possibly with the
* side effect of writing it out, by using one of
* bwrite
* bdwrite
* bawrite
* brelse
*/
struct buf bfreelist[BQUEUES];
struct buf bswlist, *bclnlist;
#define BUFHSZ 63
struct bufhd bufhash[BUFHSZ];
#define BUFHASH(dev, dblkno) \
((struct buf *)&bufhash[((int)(dev)+(int)(dblkno)) % BUFHSZ])
/*
* Initialize hash links for buffers.
*/
bhinit()
{
register int i;
register struct bufhd *bp;
for (bp = bufhash, i = 0; i < BUFHSZ; i++, bp++)
bp->b_forw = bp->b_back = (struct buf *)bp;
}
/* #define DISKMON 1 */
#ifdef DISKMON
struct {
int nbuf;
long nread;
long nreada;
long ncache;
long nwrite;
long bufcount[64];
} io_info;
#endif
/*
* Swap IO headers -
* They contain the necessary information for the swap I/O.
* At any given time, a swap header can be in three
* different lists. When free it is in the free list,
* when allocated and the I/O queued, it is on the swap
* device list, and finally, if the operation was a dirty
* page push, when the I/O completes, it is inserted
* in a list of cleaned pages to be processed by the pageout daemon.
*/
struct buf *swbuf;
short *swsize; /* CAN WE JUST USE B_BCOUNT? */
int *swpf;
#ifndef UNFAST
#define notavail(bp) \
{ \
int s = spl6(); \
(bp)->av_back->av_forw = (bp)->av_forw; \
(bp)->av_forw->av_back = (bp)->av_back; \
(bp)->b_flags |= B_BUSY; \
splx(s); \
}
#endif
/*
* Read in (if necessary) the block and return a buffer pointer.
*/
struct buf *
bread(dev, blkno)
dev_t dev;
daddr_t blkno;
{
register struct buf *bp;
bp = getblk(dev, blkno);
if (bp->b_flags&B_DONE) {
#ifdef TRACE
trace(TR_BREADHIT, dev, blkno);
#endif
#ifdef DISKMON
io_info.ncache++;
#endif
return(bp);
}
bp->b_flags |= B_READ;
bp->b_bcount = BSIZE;
(*bdevsw[major(dev)].d_strategy)(bp);
#ifdef TRACE
trace(TR_BREADMISS, dev, blkno);
#endif
#ifdef DISKMON
io_info.nread++;
#endif
u.u_vm.vm_inblk++; /* pay for read */
iowait(bp);
return(bp);
}
/*
* Read in the block, like bread, but also start I/O on the
* read-ahead block (which is not allocated to the caller)
*/
struct buf *
breada(dev, blkno, rablkno)
dev_t dev;
daddr_t blkno, rablkno;
{
register struct buf *bp, *rabp;
bp = NULL;
if (!incore(dev, blkno)) {
bp = getblk(dev, blkno);
if ((bp->b_flags&B_DONE) == 0) {
bp->b_flags |= B_READ;
bp->b_bcount = BSIZE;
(*bdevsw[major(dev)].d_strategy)(bp);
#ifdef TRACE
trace(TR_BREADMISS, dev, blkno);
#endif
#ifdef DISKMON
io_info.nread++;
#endif
u.u_vm.vm_inblk++; /* pay for read */
}
#ifdef TRACE
else
trace(TR_BREADHIT, dev, blkno);
#endif
}
if (rablkno && !incore(dev, rablkno)) {
rabp = getblk(dev, rablkno);
if (rabp->b_flags & B_DONE) {
brelse(rabp);
#ifdef TRACE
trace(TR_BREADHITRA, dev, blkno);
#endif
} else {
rabp->b_flags |= B_READ|B_ASYNC;
rabp->b_bcount = BSIZE;
(*bdevsw[major(dev)].d_strategy)(rabp);
#ifdef TRACE
trace(TR_BREADMISSRA, dev, rablock);
#endif
#ifdef DISKMON
io_info.nreada++;
#endif
u.u_vm.vm_inblk++; /* pay in advance */
}
}
if(bp == NULL)
return(bread(dev, blkno));
iowait(bp);
return(bp);
}
/*
* Write the buffer, waiting for completion.
* Then release the buffer.
*/
bwrite(bp)
register struct buf *bp;
{
register flag;
flag = bp->b_flags;
bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI | B_AGE);
bp->b_bcount = BSIZE;
#ifdef DISKMON
io_info.nwrite++;
#endif
if ((flag&B_DELWRI) == 0)
u.u_vm.vm_oublk++; /* noone paid yet */
#ifdef TRACE
trace(TR_BWRITE, bp->b_dev, bp->b_blkno);
#endif
(*bdevsw[major(bp->b_dev)].d_strategy)(bp);
if ((flag&B_ASYNC) == 0) {
iowait(bp);
brelse(bp);
} else if (flag & B_DELWRI)
bp->b_flags |= B_AGE;
else
geterror(bp);
}
/*
* Release the buffer, marking it so that if it is grabbed
* for another purpose it will be written out before being
* given up (e.g. when writing a partial block where it is
* assumed that another write for the same block will soon follow).
* This can't be done for magtape, since writes must be done
* in the same order as requested.
*/
bdwrite(bp)
register struct buf *bp;
{
register int flags;
if ((bp->b_flags&B_DELWRI) == 0)
u.u_vm.vm_oublk++; /* noone paid yet */
flags = bdevsw[major(bp->b_dev)].d_flags;
if(flags & B_TAPE)
bawrite(bp);
else {
bp->b_flags |= B_DELWRI | B_DONE;
brelse(bp);
}
}
/*
* Release the buffer, start I/O on it, but don't wait for completion.
*/
bawrite(bp)
register struct buf *bp;
{
bp->b_flags |= B_ASYNC;
bwrite(bp);
}
/*
* release the buffer, with no I/O implied.
*/
brelse(bp)
register struct buf *bp;
{
register struct buf *flist;
register s;
if (bp->b_flags&B_WANTED)
wakeup((caddr_t)bp);
if (bfreelist[0].b_flags&B_WANTED) {
bfreelist[0].b_flags &= ~B_WANTED;
wakeup((caddr_t)bfreelist);
}
if (bp->b_flags&B_ERROR)
if (bp->b_flags & B_LOCKED)
bp->b_flags &= ~B_ERROR; /* try again later */
else
bp->b_dev = NODEV; /* no assoc */
s = spl6();
if (bp->b_flags & (B_ERROR|B_INVAL)) {
/* block has no info ... put at front of most free list */
flist = &bfreelist[BQUEUES-1];
flist->av_forw->av_back = bp;
bp->av_forw = flist->av_forw;
flist->av_forw = bp;
bp->av_back = flist;
} else {
if (bp->b_flags & B_LOCKED)
flist = &bfreelist[BQ_LOCKED];
else if (bp->b_flags & B_AGE)
flist = &bfreelist[BQ_AGE];
else
flist = &bfreelist[BQ_LRU];
flist->av_back->av_forw = bp;
bp->av_back = flist->av_back;
flist->av_back = bp;
bp->av_forw = flist;
}
bp->b_flags &= ~(B_WANTED|B_BUSY|B_ASYNC|B_AGE);
splx(s);
}
/*
* See if the block is associated with some buffer
* (mainly to avoid getting hung up on a wait in breada)
*/
incore(dev, blkno)
dev_t dev;
daddr_t blkno;
{
register struct buf *bp;
register struct buf *dp;
register int dblkno = fsbtodb(blkno);
dp = BUFHASH(dev, dblkno);
for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
if (bp->b_blkno == dblkno && bp->b_dev == dev &&
!(bp->b_flags & B_INVAL))
return (1);
return (0);
}
struct buf *
baddr(dev, blkno)
dev_t dev;
daddr_t blkno;
{
if (incore(dev, blkno))
return (bread(dev, blkno));
return (0);
}
/*
* Assign a buffer for the given block. If the appropriate
* block is already associated, return it; otherwise search
* for the oldest non-busy buffer and reassign it.
*
* We use splx here because this routine may be called
* on the interrupt stack during a dump, and we don't
* want to lower the ipl back to 0.
*/
struct buf *
getblk(dev, blkno)
dev_t dev;
daddr_t blkno;
{
register struct buf *bp, *dp, *ep;
register int dblkno = fsbtodb(blkno);
#ifdef DISKMON
register int i;
#endif
int s;
if ((unsigned)blkno >= 1 << (sizeof(int)*NBBY-PGSHIFT))
blkno = 1 << ((sizeof(int)*NBBY-PGSHIFT) + 1);
dblkno = fsbtodb(blkno);
dp = BUFHASH(dev, dblkno);
loop:
for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
if (bp->b_blkno != dblkno || bp->b_dev != dev ||
bp->b_flags&B_INVAL)
continue;
s = spl6();
if (bp->b_flags&B_BUSY) {
bp->b_flags |= B_WANTED;
sleep((caddr_t)bp, PRIBIO+1);
splx(s);
goto loop;
}
splx(s);
#ifdef DISKMON
i = 0;
dp = bp->av_forw;
while ((dp->b_flags & B_HEAD) == 0) {
i++;
dp = dp->av_forw;
}
if (i<64)
io_info.bufcount[i]++;
#endif
notavail(bp);
bp->b_flags |= B_CACHE;
return(bp);
}
if (major(dev) >= nblkdev)
panic("blkdev");
s = spl6();
for (ep = &bfreelist[BQUEUES-1]; ep > bfreelist; ep--)
if (ep->av_forw != ep)
break;
if (ep == bfreelist) { /* no free blocks at all */
ep->b_flags |= B_WANTED;
sleep((caddr_t)ep, PRIBIO+1);
splx(s);
goto loop;
}
splx(s);
bp = ep->av_forw;
notavail(bp);
if (bp->b_flags & B_DELWRI) {
bp->b_flags |= B_ASYNC;
bwrite(bp);
goto loop;
}
#ifdef TRACE
trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
#endif
bp->b_flags = B_BUSY;
bp->b_back->b_forw = bp->b_forw;
bp->b_forw->b_back = bp->b_back;
bp->b_forw = dp->b_forw;
bp->b_back = dp;
dp->b_forw->b_back = bp;
dp->b_forw = bp;
bp->b_dev = dev;
bp->b_blkno = dblkno;
return(bp);
}
/*
* get an empty block,
* not assigned to any particular device
*/
struct buf *
geteblk()
{
register struct buf *bp, *dp;
int s;
loop:
s = spl6();
for (dp = &bfreelist[BQUEUES-1]; dp > bfreelist; dp--)
if (dp->av_forw != dp)
break;
if (dp == bfreelist) { /* no free blocks */
dp->b_flags |= B_WANTED;
sleep((caddr_t)dp, PRIBIO+1);
goto loop;
}
splx(s);
bp = dp->av_forw;
notavail(bp);
if (bp->b_flags & B_DELWRI) {
bp->b_flags |= B_ASYNC;
bwrite(bp);
goto loop;
}
#ifdef TRACE
trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
#endif
bp->b_flags = B_BUSY|B_INVAL;
bp->b_back->b_forw = bp->b_forw;
bp->b_forw->b_back = bp->b_back;
bp->b_forw = dp->b_forw;
bp->b_back = dp;
dp->b_forw->b_back = bp;
dp->b_forw = bp;
bp->b_dev = (dev_t)NODEV;
return(bp);
}
/*
* Wait for I/O completion on the buffer; return errors
* to the user.
*/
iowait(bp)
register struct buf *bp;
{
int s;
s = spl6();
while ((bp->b_flags&B_DONE)==0)
sleep((caddr_t)bp, PRIBIO);
splx(s);
geterror(bp);
}
#ifdef UNFAST
/*
* Unlink a buffer from the available list and mark it busy.
* (internal interface)
*/
notavail(bp)
register struct buf *bp;
{
register s;
s = spl6();
bp->av_back->av_forw = bp->av_forw;
bp->av_forw->av_back = bp->av_back;
bp->b_flags |= B_BUSY;
splx(s);
}
#endif
/*
* Mark I/O complete on a buffer. If the header
* indicates a dirty page push completion, the
* header is inserted into the ``cleaned'' list
* to be processed by the pageout daemon. Otherwise
* release it if I/O is asynchronous, and wake
* up anyone waiting for it.
*/
iodone(bp)
register struct buf *bp;
{
register int s;
if (bp->b_flags & B_DONE)
panic("dup iodone");
bp->b_flags |= B_DONE;
if (bp->b_flags & B_DIRTY) {
if (bp->b_flags & B_ERROR)
panic("IO err in push");
s = spl6();
bp->av_forw = bclnlist;
bp->b_bcount = swsize[bp - swbuf];
bp->b_pfcent = swpf[bp - swbuf];
cnt.v_pgout++;
cnt.v_pgpgout += bp->b_bcount / NBPG;
bclnlist = bp;
if (bswlist.b_flags & B_WANTED)
wakeup((caddr_t)&proc[2]);
splx(s);
return;
}
if (bp->b_flags&B_ASYNC)
brelse(bp);
else {
bp->b_flags &= ~B_WANTED;
wakeup((caddr_t)bp);
}
}
/*
* Zero the core associated with a buffer.
*/
clrbuf(bp)
struct buf *bp;
{
register *p;
register c;
p = bp->b_un.b_words;
c = BSIZE/sizeof(int);
do
*p++ = 0;
while (--c);
bp->b_resid = 0;
}
/*
* swap I/O -
*
* If the flag indicates a dirty page push initiated
* by the pageout daemon, we map the page into the i th
* virtual page of process 2 (the daemon itself) where i is
* the index of the swap header that has been allocated.
* We simply initialize the header and queue the I/O but
* do not wait for completion. When the I/O completes,
* iodone() will link the header to a list of cleaned
* pages to be processed by the pageout daemon.
*/
swap(p, dblkno, addr, nbytes, rdflg, flag, dev, pfcent)
struct proc *p;
swblk_t dblkno;
caddr_t addr;
int flag, nbytes;
dev_t dev;
unsigned pfcent;
{
register struct buf *bp;
register int c;
int p2dp;
register struct pte *dpte, *vpte;
int s;
s = spl6();
while (bswlist.av_forw == NULL) {
bswlist.b_flags |= B_WANTED;
sleep((caddr_t)&bswlist, PSWP+1);
}
bp = bswlist.av_forw;
bswlist.av_forw = bp->av_forw;
splx(s);
bp->b_flags = B_BUSY | B_PHYS | rdflg | flag;
if ((bp->b_flags & (B_DIRTY|B_PGIN)) == 0)
if (rdflg == B_READ)
sum.v_pswpin += btoc(nbytes);
else
sum.v_pswpout += btoc(nbytes);
bp->b_proc = p;
if (flag & B_DIRTY) {
p2dp = ((bp - swbuf) * CLSIZE) * KLMAX;
dpte = dptopte(&proc[2], p2dp);
vpte = vtopte(p, btop(addr));
for (c = 0; c < nbytes; c += NBPG) {
if (vpte->pg_pfnum == 0 || vpte->pg_fod)
panic("swap bad pte");
*dpte++ = *vpte++;
}
bp->b_un.b_addr = (caddr_t)ctob(p2dp);
} else
bp->b_un.b_addr = addr;
while (nbytes > 0) {
c = imin(ctob(120), nbytes);
bp->b_bcount = c;
bp->b_blkno = dblkno;
bp->b_dev = dev;
if (flag & B_DIRTY) {
swpf[bp - swbuf] = pfcent;
swsize[bp - swbuf] = nbytes;
}
#ifdef TRACE
trace(TR_SWAPIO, dev, bp->b_blkno);
#endif
(*bdevsw[major(dev)].d_strategy)(bp);
if (flag & B_DIRTY) {
if (c < nbytes)
panic("big push");
return;
}
s = spl6();
while((bp->b_flags&B_DONE)==0)
sleep((caddr_t)bp, PSWP);
splx(s);
bp->b_un.b_addr += c;
bp->b_flags &= ~B_DONE;
if (bp->b_flags & B_ERROR) {
if ((flag & (B_UAREA|B_PAGET)) || rdflg == B_WRITE)
panic("hard IO err in swap");
swkill(p, (char *)0);
}
nbytes -= c;
dblkno += btoc(c);
}
s = spl6();
bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS|B_PAGET|B_UAREA|B_DIRTY);
bp->av_forw = bswlist.av_forw;
bswlist.av_forw = bp;
if (bswlist.b_flags & B_WANTED) {
bswlist.b_flags &= ~B_WANTED;
wakeup((caddr_t)&bswlist);
wakeup((caddr_t)&proc[2]);
}
splx(s);
}
/*
* If rout == 0 then killed on swap error, else
* rout is the name of the routine where we ran out of
* swap space.
*/
swkill(p, rout)
struct proc *p;
char *rout;
{
char *mesg;
printf("pid %d: ", p->p_pid);
if (rout)
printf(mesg = "killed due to no swap space\n");
else
printf(mesg = "killed on swap error\n");
uprintf("sorry, pid %d was %s", p->p_pid, mesg);
/*
* To be sure no looping (e.g. in vmsched trying to
* swap out) mark process locked in core (as though
* done by user) after killing it so noone will try
* to swap it out.
*/
psignal(p, SIGKILL);
p->p_flag |= SULOCK;
}
/*
* make sure all write-behind blocks
* on dev (or NODEV for all)
* are flushed out.
* (from umount and update)
*/
bflush(dev)
dev_t dev;
{
register struct buf *bp;
register struct buf *flist;
int s;
loop:
s = spl6();
for (flist = bfreelist; flist < &bfreelist[BQUEUES]; flist++)
for (bp = flist->av_forw; bp != flist; bp = bp->av_forw) {
if (bp->b_flags&B_DELWRI && (dev == NODEV||dev==bp->b_dev)) {
bp->b_flags |= B_ASYNC;
notavail(bp);
bwrite(bp);
goto loop;
}
}
splx(s);
}
/*
* Raw I/O. The arguments are
* The strategy routine for the device
* A buffer, which will always be a special buffer
* header owned exclusively by the device for this purpose
* The device number
* Read/write flag
* Essentially all the work is computing physical addresses and
* validating them.
* If the user has the proper access privilidges, the process is
* marked 'delayed unlock' and the pages involved in the I/O are
* faulted and locked. After the completion of the I/O, the above pages
* are unlocked.
*/
physio(strat, bp, dev, rw, mincnt)
int (*strat)();
register struct buf *bp;
unsigned (*mincnt)();
{
register int c;
char *a;
int s;
if (useracc(u.u_base,u.u_count,rw==B_READ?B_WRITE:B_READ) == NULL) {
u.u_error = EFAULT;
return;
}
s = spl6();
while (bp->b_flags&B_BUSY) {
bp->b_flags |= B_WANTED;
sleep((caddr_t)bp, PRIBIO+1);
}
bp->b_error = 0;
bp->b_proc = u.u_procp;
bp->b_un.b_addr = u.u_base;
while (u.u_count != 0) {
bp->b_flags = B_BUSY | B_PHYS | rw;
bp->b_dev = dev;
bp->b_blkno = u.u_offset >> PGSHIFT;
bp->b_bcount = u.u_count;
(*mincnt)(bp);
c = bp->b_bcount;
u.u_procp->p_flag |= SPHYSIO;
vslock(a = bp->b_un.b_addr, c);
(*strat)(bp);
(void) spl6();
while ((bp->b_flags&B_DONE) == 0)
sleep((caddr_t)bp, PRIBIO);
vsunlock(a, c, rw);
u.u_procp->p_flag &= ~SPHYSIO;
if (bp->b_flags&B_WANTED)
wakeup((caddr_t)bp);
splx(s);
bp->b_un.b_addr += c;
u.u_count -= c;
u.u_offset += c;
if (bp->b_flags&B_ERROR)
break;
}
bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS);
u.u_count = bp->b_resid;
geterror(bp);
}
/*ARGSUSED*/
unsigned
minphys(bp)
struct buf *bp;
{
if (bp->b_bcount > 60 * 1024)
bp->b_bcount = 60 * 1024;
}
/*
* Pick up the device's error number and pass it to the user;
* if there is an error but the number is 0 set a generalized
* code. Actually the latter is always true because devices
* don't yet return specific errors.
*/
geterror(bp)
register struct buf *bp;
{
if (bp->b_flags&B_ERROR)
if ((u.u_error = bp->b_error)==0)
u.u_error = EIO;
}
/*
* Invalidate in core blocks belonging to closed or umounted filesystem
*
* This is not nicely done at all - the buffer ought to be removed from the
* hash chains & have its dev/blkno fields clobbered, but unfortunately we
* can't do that here, as it is quite possible that the block is still
* being used for i/o. Eventually, all disc drivers should be forced to
* have a close routine, which ought ensure that the queue is empty, then
* properly flush the queues. Until that happy day, this suffices for
* correctness. ... kre
*/
binval(dev)
dev_t dev;
{
register struct buf *bp;
register struct bufhd *hp;
#define dp ((struct buf *)hp)
for (hp = bufhash; hp < &bufhash[BUFHSZ]; hp++)
for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
if (bp->b_dev == dev)
bp->b_flags |= B_INVAL;
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.