From: Alan Cox <alan@linux.intel.com>
Date: Fri, 15 May 2015 23:47:58 +0000 (+0100)
Subject: devio: Fix the long standing buffer flushing FIXME
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=ce1b0f4f1a184ca2813a3c7e95d32a0f2241917b;p=FUZIX.git

devio: Fix the long standing buffer flushing FIXME

We now drop buffers on the final close of a device. This makes mounting
different floppy disks work reliably.
---

diff --git a/Kernel/devio.c b/Kernel/devio.c
index 6eed6475..a6a19af8 100644
--- a/Kernel/devio.c
+++ b/Kernel/devio.c
@@ -116,18 +116,23 @@ void *zerobuf(void)
 	return b;
 }
 
+static void bdput(bufptr bp)
+{
+	bdwrite(bp);
+	if (bp->bf_busy == BF_FREE)
+		bp->bf_dirty = false;
+	d_flush(bp->bf_dev);
+}
 
 void bufsync(void)
 {
 	bufptr bp;
 
+	/* FIXME: this can generate a lot of d_flush calls when you have
+	   plenty of buffers */
 	for (bp = bufpool; bp < bufpool + NBUFS; ++bp) {
-		if ((bp->bf_dev != NO_DEVICE) && bp->bf_dirty) {
-			bdwrite(bp);
-			if (bp->bf_busy == BF_FREE)
-				bp->bf_dirty = false;
-			d_flush(bp->bf_dev);
-		}
+		if ((bp->bf_dev != NO_DEVICE) && bp->bf_dirty)
+		        bdput(bp);
 	}
 }
 
@@ -142,6 +147,17 @@ bufptr bfind(uint16_t dev, blkno_t blk)
 	return NULL;
 }
 
+void bdrop(uint16_t dev)
+{
+	bufptr bp;
+
+	for (bp = bufpool; bp < bufpool + NBUFS; ++bp) {
+		if (bp->bf_dev == dev) {
+		        bdput(bp);
+		        bp->bf_dev = NO_DEVICE;
+                }
+	}
+}
 
 bufptr freebuf(void)
 {
@@ -242,8 +258,6 @@ int cdwrite(uint16_t dev, uint8_t flag)
 	return ((*dev_tab[major(dev)].dev_write) (minor(dev), 1, flag));
 }
 
-// WRS: swapread(), swapwrite() removed.
-
 int d_open(uint16_t dev, uint8_t flag)
 {
 	if (!validdev(dev))
@@ -251,14 +265,11 @@ int d_open(uint16_t dev, uint8_t flag)
 	return ((*dev_tab[major(dev)].dev_open) (minor(dev), flag));
 }
 
-
-/* FIXME: on the last close we ought to flush/invalidate any bufs
-   for this device so we can support swapping between media properly
-   (right now the cache is so small it happens to work...) */
 int d_close(uint16_t dev)
 {
 	if (!validdev(dev))
 		panic("d_close: bad device");
+        bdrop(dev);
 	return (*dev_tab[major(dev)].dev_close) (minor(dev));
 }
 
diff --git a/Kernel/include/kernel.h b/Kernel/include/kernel.h
index 8f972e07..dd4db59e 100644
--- a/Kernel/include/kernel.h
+++ b/Kernel/include/kernel.h
@@ -632,6 +632,7 @@ extern void *tmpbuf(void);
 extern void *zerobuf(void);
 extern void bufsync(void);
 extern bufptr bfind(uint16_t dev, blkno_t blk);
+extern void bdrop(uint16_t dev);
 extern bufptr freebuf(void);
 extern void bufinit(void);
 extern void bufdiscard(bufptr bp);