xv6/bio.c
rtm 4357207237 fix getblk to actually lock the block
no more cons_put system calls
usertests tests two processes writing files
2006-08-12 11:38:57 +00:00

92 lines
1.5 KiB
C

#include "types.h"
#include "param.h"
#include "x86.h"
#include "mmu.h"
#include "proc.h"
#include "defs.h"
#include "spinlock.h"
#include "buf.h"
struct buf buf[NBUF];
struct spinlock buf_table_lock;
void
binit(void)
{
initlock(&buf_table_lock, "buf_table");
}
struct buf *
getblk(uint dev, uint sector)
{
struct buf *b;
acquire(&buf_table_lock);
while(1){
for(b = buf; b < buf+NBUF; b++)
if((b->flags & B_BUSY) && b->dev == dev && b->sector)
break;
if(b < buf+NBUF){
sleep(buf, &buf_table_lock);
} else {
for(b = buf; b < buf+NBUF; b++){
if((b->flags & B_BUSY) == 0){
b->flags |= B_BUSY;
b->dev = dev;
b->sector = sector;
release(&buf_table_lock);
return b;
}
}
panic("getblk: no buffers");
}
}
}
struct buf *
bread(uint dev, uint sector)
{
void *c;
struct buf *b;
extern struct spinlock ide_lock;
b = getblk(dev, sector);
acquire(&ide_lock);
c = ide_start_rw(dev & 0xff, sector, b->data, 1, 1);
sleep (c, &ide_lock);
ide_finish(c);
release(&ide_lock);
return b;
}
void
bwrite(uint dev, struct buf *b, uint sector)
{
void *c;
extern struct spinlock ide_lock;
acquire(&ide_lock);
c = ide_start_rw(dev & 0xff, sector, b->data, 1, 0);
sleep (c, &ide_lock);
ide_finish(c);
release(&ide_lock);
}
void
brelse(struct buf *b)
{
if((b->flags & B_BUSY) == 0)
panic("brelse");
acquire(&buf_table_lock);
b->flags &= ~B_BUSY;
wakeup(buf);
release(&buf_table_lock);
}