Import sources from 2011-03-30 iso image

1 files changed, 197 insertions, 0 deletions

diff --git a/sys/src/cmd/cfs/bcache.c b/sys/src/cmd/cfs/bcache.c
new file mode 100755
index 000000000..becd675ea
--- /dev/null
+++ b/sys/src/cmd/cfs/bcache.c
@@ -0,0 +1,197 @@
+#include <u.h>
+#include <libc.h>
+#include "cformat.h"
+#include "lru.h"
+#include "bcache.h"
+
+int
+bcinit(Bcache *bc, int f, int bsize)
+{
+	Bbuf *b;
+
+	/*
+	 *  allocate space for all buffers
+	 *  point all buffers into outer space
+	 */
+	bc->dfirst = 0;
+	bc->bsize = bsize;
+	bc->f = f;
+	lruinit(bc);
+	for(b = bc->bb; b < &bc->bb[Nbcache]; b++){
+		b->inuse = 0;
+		b->next = 0;
+		b->dirty = 0;
+		if(b->data == 0)
+			b->data = (char *)malloc(bc->bsize);
+		if(b->data == 0)
+			return -1;
+		lruadd(bc, b);
+	}
+
+	return 0;
+}
+
+/*
+ *  Find a buffer for block b.  If it's dirty, write it out.
+ */
+Bbuf *
+bcfind(Bcache *bc, ulong bno)
+{
+	Bbuf *b;
+
+	if(bno == Notabno)
+		error("bcfind: Notabno");
+	bno &= ~Indbno;
+
+	/*
+	 *  if we already have a buffer for this bno, use it
+	 */
+	for(b = bc->bb; b < &bc->bb[Nbcache]; b++)
+		if(b->inuse && b->bno==bno)
+			goto out;
+
+	/*
+	 *  get least recently used block
+	 */
+	b = (Bbuf*)bc->lnext;
+out:
+	/*
+	 *  if dirty, write it out
+	 */
+	if(b->dirty)
+		if(bcwrite(bc, b) < 0)
+			warning("writing dirty page");
+	lruref(bc, b);
+	return b;
+}
+
+/*
+ *  allocate a buffer block for a block.  it's guaranteed to be there till
+ *  the next Nbcache bcread's.
+ */
+Bbuf *
+bcalloc(Bcache *bc, ulong bno)
+{
+	Bbuf *b;
+
+	b = bcfind(bc, bno);
+	bno &= ~Indbno;
+	b->bno = bno;
+	b->inuse = 1;
+	return b;
+}
+
+/*
+ *  read a block into a buffer cache.  it's guaranteed to be there till
+ *  the next Nbcache bcread's.
+ */
+Bbuf *
+bcread(Bcache *bc, ulong bno)
+{
+	Bbuf *b;
+
+	b = bcfind(bc, bno);
+	bno &= ~Indbno;
+	if(b->bno!=bno || !b->inuse)
+		/*
+		 *  read in the one we really want
+		 */
+		if(bread(bc, bno, b->data) < 0){
+			b->inuse = 0;
+			return 0;
+		}
+	b->bno = bno;
+	b->inuse = 1;
+	return b;
+}
+
+/*
+ *  mark a page dirty, if it's already dirty force a write
+ *
+ *	N.B: ordering is important.
+ */
+void
+bcmark(Bcache *bc, Bbuf *b)
+{
+	lruref(bc, b);
+
+	if(b->dirty){
+		bcwrite(bc, b);
+		return;
+	}
+
+	b->dirty = 1;
+	if(bc->dfirst)
+		bc->dlast->next = b;
+	else
+		bc->dfirst = b;
+	bc->dlast = b;
+}
+
+/*
+ *  write out a page (and all preceding dirty ones)
+ */
+int
+bcwrite(Bcache *bc, Bbuf *b)
+{
+	Bbuf *nb;
+
+	/*
+	 *  write out all preceding pages
+	 */
+	while(nb = bc->dfirst){
+		if(bwrite(bc, nb->bno, nb->data) < 0)
+			return -1;
+		nb->dirty = 0;
+		bc->dfirst = nb->next;
+		nb->next = 0;
+		if(nb == b)
+			return 0;
+	}
+
+	/*
+	 *  write out this page
+	 */
+	if(bwrite(bc, b->bno, b->data) < 0)
+		return -1;
+	b->dirty = 0;
+	b->next = 0;
+	return 0;
+}
+
+/*
+ *  write out all dirty pages (in order)
+ */
+int
+bcsync(Bcache *bc)
+{
+	if(bc->dfirst)
+		return bcwrite(bc, bc->dlast);
+	return 0;
+}
+
+/*
+ *  read a block from disk
+ */
+int
+bread(Bcache *bc, ulong bno, void *buf)
+{
+	uvlong x = (uvlong)bno * bc->bsize;
+
+	if(pread(bc->f, buf, bc->bsize, x) != bc->bsize)
+		return -1;
+	return 0;
+}
+
+/*
+ *  write a block to disk
+ */
+int
+bwrite(Bcache *bc, ulong bno, void *buf)
+{
+	uvlong x = (uvlong)bno * bc->bsize;
+
+	if(pwrite(bc->f, buf, bc->bsize, x) != bc->bsize)
+		return -1;
+	return 0;
+}