From 5753553213df8f9de851adb68377db43faecb91f Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Tue, 11 Jun 2019 09:57:14 -0400
Subject: separate source into kernel/ user/ mkfs/

---
 bio.c | 145 ------------------------------------------------------------------
 1 file changed, 145 deletions(-)
 delete mode 100644 bio.c

(limited to 'bio.c')

diff --git a/bio.c b/bio.c
deleted file mode 100644
index 90f9af9..0000000
--- a/bio.c
+++ /dev/null
@@ -1,145 +0,0 @@
-// Buffer cache.
-//
-// The buffer cache is a linked list of buf structures holding
-// cached copies of disk block contents.  Caching disk blocks
-// in memory reduces the number of disk reads and also provides
-// a synchronization point for disk blocks used by multiple processes.
-//
-// Interface:
-// * To get a buffer for a particular disk block, call bread.
-// * After changing buffer data, call bwrite to write it to disk.
-// * When done with the buffer, call brelse.
-// * Do not use the buffer after calling brelse.
-// * Only one process at a time can use a buffer,
-//     so do not keep them longer than necessary.
-//
-// The implementation uses two state flags internally:
-// * B_VALID: the buffer data has been read from the disk.
-// * B_DIRTY: the buffer data has been modified
-//     and needs to be written to disk.
-
-#include "types.h"
-#include "param.h"
-#include "spinlock.h"
-#include "sleeplock.h"
-#include "riscv.h"
-#include "defs.h"
-#include "fs.h"
-#include "buf.h"
-
-struct {
-  struct spinlock lock;
-  struct buf buf[NBUF];
-
-  // Linked list of all buffers, through prev/next.
-  // head.next is most recently used.
-  struct buf head;
-} bcache;
-
-void
-binit(void)
-{
-  struct buf *b;
-
-  initlock(&bcache.lock, "bcache");
-
-//PAGEBREAK!
-  // Create linked list of buffers
-  bcache.head.prev = &bcache.head;
-  bcache.head.next = &bcache.head;
-  for(b = bcache.buf; b < bcache.buf+NBUF; b++){
-    b->next = bcache.head.next;
-    b->prev = &bcache.head;
-    initsleeplock(&b->lock, "buffer");
-    bcache.head.next->prev = b;
-    bcache.head.next = b;
-  }
-}
-
-// Look through buffer cache for block on device dev.
-// If not found, allocate a buffer.
-// In either case, return locked buffer.
-static struct buf*
-bget(uint dev, uint blockno)
-{
-  struct buf *b;
-
-  acquire(&bcache.lock);
-
-  // Is the block already cached?
-  for(b = bcache.head.next; b != &bcache.head; b = b->next){
-    if(b->dev == dev && b->blockno == blockno){
-      b->refcnt++;
-      release(&bcache.lock);
-      acquiresleep(&b->lock);
-      return b;
-    }
-  }
-
-  // Not cached; recycle an unused buffer.
-  // Even if refcnt==0, B_DIRTY indicates a buffer is in use
-  // because log.c has modified it but not yet committed it.
-  for(b = bcache.head.prev; b != &bcache.head; b = b->prev){
-    if(b->refcnt == 0 && (b->flags & B_DIRTY) == 0) {
-      b->dev = dev;
-      b->blockno = blockno;
-      b->flags = 0;
-      b->refcnt = 1;
-      release(&bcache.lock);
-      acquiresleep(&b->lock);
-      return b;
-    }
-  }
-  panic("bget: no buffers");
-}
-
-// Return a locked buf with the contents of the indicated block.
-struct buf*
-bread(uint dev, uint blockno)
-{
-  struct buf *b;
-
-  b = bget(dev, blockno);
-  if((b->flags & B_VALID) == 0) {
-    ramdiskrw(b);
-  }
-  return b;
-}
-
-// Write b's contents to disk.  Must be locked.
-void
-bwrite(struct buf *b)
-{
-  if(!holdingsleep(&b->lock))
-    panic("bwrite");
-  b->flags |= B_DIRTY;
-  ramdiskrw(b);
-}
-
-// Release a locked buffer.
-// Move to the head of the MRU list.
-void
-brelse(struct buf *b)
-{
-  if(!holdingsleep(&b->lock))
-    panic("brelse");
-
-  releasesleep(&b->lock);
-
-  acquire(&bcache.lock);
-  b->refcnt--;
-  if (b->refcnt == 0) {
-    // no one is waiting for it.
-    b->next->prev = b->prev;
-    b->prev->next = b->next;
-    b->next = bcache.head.next;
-    b->prev = &bcache.head;
-    bcache.head.next->prev = b;
-    bcache.head.next = b;
-  }
-  
-  release(&bcache.lock);
-}
-//PAGEBREAK!
-// Blank page.
-
-- 
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