sys/src/cmd/ext2srv/iobuf.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <fcall.h>
   4 #include <thread.h>
   5 #include <9p.h>
   6 #include "dat.h"
   7 #include "fns.h"
   8
   9 #define NIOBUF          100
  10 #define HIOB            (NIOBUF/3)
  11
  12 static Iobuf*   hiob[HIOB];             /* hash buckets */
  13 static Iobuf    iobuf[NIOBUF];          /* buffer headers */
  14 static Iobuf*   iohead;
  15 static Iobuf*   iotail;
  16
  17 Iobuf*
  18 getbuf(Xfs *dev, long addr)
  19 {
  20         Iobuf *p, *h, **l, **f;
  21
  22         l = &hiob[addr%HIOB];
  23         for(p = *l; p; p = p->hash) {
  24                 if(p->addr == addr && p->dev == dev) {
  25                         p->busy++;
  26                         return p;
  27                 }
  28         }
  29         /* Find a non-busy buffer from the tail */
  30         for(p = iotail; p && (p->busy > 0); p = p->prev)
  31                 ;
  32         if(!p)
  33                 panic("all buffers busy");
  34         if(p->dirty){
  35                 xwrite(p);
  36                 p->dirty = 0;
  37         }
  38
  39         if( xread(dev, p, addr) < 0)
  40                 return 0;
  41         /* Delete from hash chain */
  42         f = &hiob[p->addr%HIOB];
  43         if( *f == p )
  44                 *f = p->hash;
  45         else {
  46                 for(h = *f; h ; h = h->hash)
  47                         if( h->hash == p ){
  48                                 h->hash = p->hash;
  49                                 break;
  50                         }
  51         }
  52         /* Fill and hash */
  53         p->hash = *l;
  54         *l = p;
  55         p->addr = addr;
  56         p->dev = dev;
  57         p->busy=1;
  58
  59         return p;
  60 }
  61 void
  62 putbuf(Iobuf *p)
  63 {
  64         if(p->busy <= 0)
  65                 panic("putbuf");
  66         p->busy--;
  67
  68         /* Link onto head for lru */
  69         if(p == iohead)
  70                 return;
  71         if( p == iotail ){
  72                 p->prev->next = 0;
  73                 iotail = p->prev;
  74         }else{
  75                 p->prev->next = p->next;
  76                 p->next->prev = p->prev;
  77         }
  78
  79         p->prev = 0;
  80         p->next = iohead;
  81         iohead->prev = p;
  82         iohead = p;
  83 }
  84 void
  85 dirtybuf(Iobuf *p)
  86 {
  87         if(p->busy <=0)
  88                 panic("dirtybuf");
  89         p->dirty = 1;
  90 }
  91 void
  92 syncbuf(void)
  93 {
  94         Iobuf *p;
  95
  96         for(p=&iobuf[0] ; p<&iobuf[NIOBUF]; p++)
  97                 if( p->dirty ){
  98                         xwrite(p);
  99                         p->dirty = 0;
 100                 }
 101 }
 102 void
 103 purgebuf(Xfs *dev)
 104 {
 105         Iobuf *p;
 106
 107         for(p=&iobuf[0]; p<&iobuf[NIOBUF]; p++)
 108                 if(p->dev == dev)
 109                         p->busy = 0;
 110
 111         /* Blow hash chains */
 112         memset(hiob, 0, sizeof(hiob));
 113 }
 114 void
 115 iobuf_init(void)
 116 {
 117         Iobuf *p;
 118
 119         iohead = iobuf;
 120         iotail = iobuf+NIOBUF-1;
 121
 122         for(p = iobuf; p <= iotail; p++) {
 123                 p->next = p+1;
 124                 p->prev = p-1;
 125
 126                 p->iobuf = (char *)malloc(EXT2_MAX_BLOCK_SIZE);
 127                 if(p->iobuf == 0)
 128                         panic("iobuf_init");
 129         }
 130
 131         iohead->prev = 0;
 132         iotail->next = 0;
 133 }
 134 int
 135 xread(Xfs *dev, Iobuf *p, long addr)
 136 {
 137         /*chat("xread %d,%d...", dev->dev, addr);*/
 138
 139         seek(dev->dev, (vlong)addr*dev->block_size, 0);
 140         if(read(dev->dev, p->iobuf, dev->block_size) != dev->block_size){
 141                 chat("xread %d, block=%d failed ...", dev->dev, addr);
 142                 errno = Eio;
 143                 return -1;
 144         }
 145         /*chat("xread ok...");*/
 146         return 0;
 147 }
 148 void
 149 xwrite(Iobuf *p)
 150 {
 151         Xfs *dev;
 152         long addr;
 153
 154         dev = p->dev;
 155         addr = p->addr;
 156         /*chat("xwrite %d,%d...", dev->dev, addr);*/
 157
 158         seek(dev->dev, (vlong)addr*dev->block_size, 0);
 159         if(write(dev->dev, p->iobuf, dev->block_size) != dev->block_size){
 160                 chat("xwrite %d, block=%d failed ...", dev->dev, addr);
 161                 errno = Eio;
 162                 return;
 163         }
 164         /*chat("xwrite ok...");*/
 165 }
 166 void
 167 dumpbuf(void)
 168 {
 169         Iobuf *p;
 170
 171         for(p = iotail; p ; p = p->prev)
 172                 if( p->busy )
 173                         mchat("\nHi ERROR buf(%x, %d, %d)\n", p, p->addr, p->busy);
 174 }