+#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/page.h"
+
+#define DISKMON 1
+
+#ifdef DISKMON
+struct {
+ int nbuf;
+ long nread;
+ long nreada;
+ long ncache;
+ long nwrite;
+ long bufcount[NBUF];
+} io_info;
+#endif
+
+/*
+ * swap IO headers.
+ * they are filled in to point
+ * at the desired IO operation.
+ */
+struct buf swbuf1;
+struct buf swbuf2;
+
+/*
+ * 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
+ * Eventually the buffer must be released, possibly with the
+ * side effect of writing it out, by using one of
+ * bwrite
+ * bdwrite
+ * bawrite
+ * brelse
+ */
+
+/*
+ * 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 DISKMON
+ io_info.ncache++;
+#endif
+ return(bp);
+ }
+ bp->b_flags |= B_READ;
+ bp->b_bcount = BSIZE;
+ (*bdevsw[major(dev)].d_strategy)(bp);
+#ifdef DISKMON
+ io_info.nread++;
+#endif
+ 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 DISKMON
+ io_info.nread++;
+#endif
+ }
+ }
+ if (rablkno && !incore(dev, rablkno)) {
+ rabp = getblk(dev, rablkno);
+ if (rabp->b_flags & B_DONE)
+ brelse(rabp);
+ else {
+ rabp->b_flags |= B_READ|B_ASYNC;
+ rabp->b_bcount = BSIZE;
+ (*bdevsw[major(dev)].d_strategy)(rabp);
+#ifdef DISKMON
+ io_info.nreada++;
+#endif
+ }
+ }
+ 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
+ (*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 struct buf *dp;
+
+ dp = bdevsw[major(bp->b_dev)].d_tab;
+ if(dp->b_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 **backp;
+ register s;
+
+ if (bp->b_flags&B_WANTED)
+ wakeup((caddr_t)bp);
+ if (bfreelist.b_flags&B_WANTED) {
+ bfreelist.b_flags &= ~B_WANTED;
+ wakeup((caddr_t)&bfreelist);
+ }
+ if (bp->b_flags&B_ERROR)
+ bp->b_dev = NODEV; /* no assoc. on error */
+ s = spl6();
+ if(bp->b_flags & B_AGE) {
+ backp = &bfreelist.av_forw;
+ (*backp)->av_back = bp;
+ bp->av_forw = *backp;
+ *backp = bp;
+ bp->av_back = &bfreelist;
+ } else {
+ backp = &bfreelist.av_back;
+ (*backp)->av_forw = bp;
+ bp->av_back = *backp;
+ *backp = bp;
+ bp->av_forw = &bfreelist;
+ }
+ 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;
+
+ dp = bdevsw[major(dev)].d_tab;
+ for (bp=dp->b_forw; bp != dp; bp = bp->b_forw)
+ if (bp->b_blkno==blkno && bp->b_dev==dev)
+ return(1);
+ 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.
+ */
+struct buf *
+getblk(dev, blkno)
+dev_t dev;
+daddr_t blkno;
+{
+ register struct buf *bp;
+ register struct buf *dp;
+#ifdef DISKMON
+ register i;
+#endif
+
+ if(major(dev) >= nblkdev)
+ panic("blkdev");
+
+ loop:
+ spl0();
+ dp = bdevsw[major(dev)].d_tab;
+ if(dp == NULL)
+ panic("devtab");
+ for (bp=dp->b_forw; bp != dp; bp = bp->b_forw) {
+ if (bp->b_blkno!=blkno || bp->b_dev!=dev)
+ continue;
+ spl6();
+ if (bp->b_flags&B_BUSY) {
+ bp->b_flags |= B_WANTED;
+ sleep((caddr_t)bp, PRIBIO+1);
+ goto loop;
+ }
+ spl0();
+#ifdef DISKMON
+ i = 0;
+ dp = bp->av_forw;
+ while (dp != &bfreelist) {
+ i++;
+ dp = dp->av_forw;
+ }
+ if (i<NBUF)
+ io_info.bufcount[i]++;
+#endif
+ notavail(bp);
+ return(bp);
+ }
+ spl6();
+ if (bfreelist.av_forw == &bfreelist) {
+ bfreelist.b_flags |= B_WANTED;
+ sleep((caddr_t)&bfreelist, PRIBIO+1);
+ goto loop;
+ }
+ spl0();
+ notavail(bp = bfreelist.av_forw);
+ if (bp->b_flags & B_DELWRI) {
+ bp->b_flags |= B_ASYNC;
+ bwrite(bp);
+ goto loop;
+ }
+ 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 = blkno;
+ return(bp);
+}
+
+/*
+ * get an empty block,
+ * not assigned to any particular device
+ */
+struct buf *
+geteblk()
+{
+ register struct buf *bp;
+ register struct buf *dp;
+
+loop:
+ spl6();
+ while (bfreelist.av_forw == &bfreelist) {
+ bfreelist.b_flags |= B_WANTED;
+ sleep((caddr_t)&bfreelist, PRIBIO+1);
+ }
+ spl0();
+ dp = &bfreelist;
+ notavail(bp = bfreelist.av_forw);
+ if (bp->b_flags & B_DELWRI) {
+ bp->b_flags |= B_ASYNC;
+ bwrite(bp);
+ goto loop;
+ }
+ 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_t)NODEV;
+ return(bp);
+}
+
+/*
+ * Wait for I/O completion on the buffer; return errors
+ * to the user.
+ */
+iowait(bp)
+register struct buf *bp;
+{
+
+ spl6();
+ while ((bp->b_flags&B_DONE)==0)
+ sleep((caddr_t)bp, PRIBIO);
+ spl0();
+ geterror(bp);
+}
+
+/*
+ * 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);
+}
+
+/*
+ * Mark I/O complete on a buffer, release it if I/O is asynchronous,
+ * and wake up anyone waiting for it.
+ */
+iodone(bp)
+register struct buf *bp;
+{
+
+ bp->b_flags |= B_DONE;
+ 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
+ */
+swap(p,blkno, coreaddr, count, rdflg,uflag)
+ struct proc *p;
+{
+ register struct buf *bp;
+ register int c, pt, i;
+ int ptab[(MAXUMEM+127)/128];
+ extern int Swap2map[], swap2utl[];
+
+ bp = &swbuf1;
+ if(bp->b_flags & B_BUSY)
+ if((swbuf2.b_flags&B_WANTED) == 0)
+ bp = &swbuf2;
+ spl6();
+ while (bp->b_flags&B_BUSY) {
+ bp->b_flags |= B_WANTED;
+ sleep((caddr_t)bp, PSWP+1);
+ }
+ if (uflag) { /* get current page table size */
+ ptaccess(p, Swap2map, swap2utl);
+ pt = ((struct user *)swap2utl)->u_pcb.pcb_szpt;
+ for(i=pt; --i>=0; )
+ ptab[i] = (Swap2map+UPAGES)[i]&PG_PFNUM;
+ }
+ bp->b_proc = p;
+ bp->b_un.b_addr = (caddr_t)ctob(coreaddr);
+ bp->b_flags = B_BUSY | B_PHYS | rdflg | (uflag ? B_UAREA : 0);
+ while (count > 0) {
+ bp->b_dev = swapdev;
+ bp->b_bcount = ctob( (c = count>120 ? 120 : count));
+ bp->b_blkno = swplo+blkno;
+ (*bdevsw[major(swapdev)].d_strategy)(bp);
+ spl6();
+ while((bp->b_flags&B_DONE)==0)
+ sleep((caddr_t)bp, PSWP);
+ if (bp->b_flags&B_WANTED)
+ wakeup((caddr_t)bp);
+ spl0();
+ bp->b_un.b_addr += ctob(c);
+ if (bp->b_flags & B_UAREA) {
+ bp->b_un.b_addr -= ctob(UPAGES);
+ if (rdflg == B_READ) { /* don't let page table size change */
+ spl6();
+ ptaccess(p, Swap2map, swap2utl);
+ ((struct user *)swap2utl)->u_pcb.pcb_szpt = pt;
+ for(i=pt; --i>=0; )
+ ((struct user *)swap2utl)->u_ptable[i]
+ = ptab[i];
+ spl0();
+ }
+ }
+ bp->b_flags &= ~(B_WANTED | B_UAREA | B_DONE);
+ if (bp->b_flags & B_ERROR)
+ panic("IO err in swap");
+ count -= c;
+ blkno += c;
+ }
+ bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS);
+}
+
+/*
+ * 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;
+
+loop:
+ spl6();
+ for (bp = bfreelist.av_forw; bp != &bfreelist; 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;
+ }
+ }
+ spl0();
+}
+
+/*
+ * 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.
+ */
+physio(strat, bp, dev, rw)
+register struct buf *bp;
+int (*strat)();
+{
+ register int c;
+ int flag = 0;
+
+ if (useracc(u.u_base,u.u_count,rw) == NULL) {
+ u.u_error =EFAULT;
+ return; }
+ 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_error==0) {
+ bp->b_flags = B_BUSY | B_PHYS | rw;
+ bp->b_dev = dev;
+ bp->b_blkno = u.u_offset >> BSHIFT;
+ bp->b_bcount = c = u.u_count>60*1024 ? 60*1024 : u.u_count;
+ flag = u.u_procp->p_flag & SULOCK;
+ u.u_procp->p_flag |= SULOCK;
+ (*strat)(bp);
+ spl6();
+ while ((bp->b_flags&B_DONE) == 0)
+ sleep((caddr_t)bp, PRIBIO);
+ u.u_procp->p_flag &= ~SULOCK;
+ u.u_procp->p_flag |= flag;
+ if (bp->b_flags&B_WANTED)
+ wakeup((caddr_t)bp);
+ spl0();
+ bp->b_un.b_addr += c;
+ u.u_count -= c;
+ u.u_offset += c;
+ }
+ bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS);
+ u.u_count = bp->b_resid;
+ geterror(bp);
+ return;
+}
+
+/*
+ * 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;
+}
projects / unix-history / commitdiff