use the buffercache for block device I/O

build.mak

@@ -102,6 +102,7 @@ fs = fs/fs.o bootfs.o
 fs +=	fs/vfs/main.o \
 	fs/vfs/kern_physio.o \
 	fs/vfs/subr_uio.o \
+	fs/vfs/vfs_bdev.o \
 	fs/vfs/vfs_bio.o \
 	fs/vfs/vfs_conf.o \
 	fs/vfs/vfs_lookup.o \

drivers/ramdisk.c

@@ -48,14 +48,25 @@ struct ramdisk_softc {
 static pthread_t ramdisk_thread;
 
 static int
-ramdisk_rdwr(struct device *dev, struct uio *uio, int ioflags)
+ramdisk_read(struct device *dev, struct uio *uio, int ioflags)
 {
 	struct ramdisk_softc *sc = dev->private_data;
 
 	if (uio->uio_offset + uio->uio_resid > sc->size)
 		return EIO;
 
-	return physio(dev, uio, ioflags);
+	return bdev_read(dev, uio, ioflags);
+}
+
+static int
+ramdisk_write(struct device *dev, struct uio *uio, int ioflags)
+{
+	struct ramdisk_softc *sc = dev->private_data;
+
+	if (uio->uio_offset + uio->uio_resid > sc->size)
+		return EIO;
+
+	return bdev_write(dev, uio, ioflags);
 }
 
 static void
@@ -91,8 +102,8 @@ ramdisk_strategy(struct bio *bio)
 static struct devops ramdisk_devops = {
 	.open		= no_open,
 	.close		= no_close,
-	.read		= ramdisk_rdwr,
-	.write		= ramdisk_rdwr,
+	.read		= ramdisk_read,
+	.write		= ramdisk_write,
 	.ioctl		= no_ioctl,
 	.devctl		= no_devctl,
 	.strategy	= ramdisk_strategy,

drivers/virtio-blk.cc

@@ -46,7 +46,7 @@ virtio_blk_strategy(struct bio *bio)
 }
 
 static int
-virtio_blk_rdwr(struct device *dev, struct uio *uio, int ioflags)
+virtio_blk_read(struct device *dev, struct uio *uio, int ioflags)
 {
     struct virtio_blk_priv *prv =
         reinterpret_cast<struct virtio_blk_priv*>(dev->private_data);
@@ -54,14 +54,26 @@ virtio_blk_rdwr(struct device *dev, struct uio *uio, int ioflags)
     if (uio->uio_offset + uio->uio_resid > prv->drv->size())
         return EIO;
 
-    return physio(dev, uio, ioflags);
+    return bdev_read(dev, uio, ioflags);
+}
+
+static int
+virtio_blk_write(struct device *dev, struct uio *uio, int ioflags)
+{
+    struct virtio_blk_priv *prv =
+        reinterpret_cast<struct virtio_blk_priv*>(dev->private_data);
+
+    if (uio->uio_offset + uio->uio_resid > prv->drv->size())
+        return EIO;
+
+    return bdev_write(dev, uio, ioflags);
 }
 
 static struct devops virtio_blk_devops = {
     .open       = no_open,
     .close      = no_close,
-    .read       = virtio_blk_rdwr,
-    .write      = virtio_blk_rdwr,
+    .read       = virtio_blk_read,
+    .write      = virtio_blk_write,
     .ioctl      = no_ioctl,
     .devctl     = no_devctl,
     .strategy   = virtio_blk_strategy,

fs/vfs/kern_physio.c

@@ -44,52 +44,3 @@ biodone(struct bio *bio)
 		bio_done(bio);
 	}
 }
-
-int
-physio(struct device *dev, struct uio *uio, int ioflags)
-{
-	struct bio *bio;
-
-	if (uio->uio_offset < 0)
-		return EINVAL;
-	if (uio->uio_resid == 0)
-		return 0;
-    
-	while (uio->uio_resid > 0) {
-		struct iovec *iov = uio->uio_iov;
-
-		if (!iov->iov_len)
-			continue;
-
-		bio = alloc_bio();
-		if (!bio)
-			return ENOMEM;
-
-		if (uio->uio_rw == UIO_READ)
-			bio->bio_cmd = BIO_READ;
-		else
-			bio->bio_cmd = BIO_WRITE;
-
-		bio->bio_dev = dev;
-		bio->bio_data = iov->iov_base;
-		bio->bio_offset = uio->uio_offset;
-		bio->bio_bcount = uio->uio_resid;
-
-		dev->driver->devops->strategy(bio);
-
-		pthread_mutex_lock(&bio->bio_mutex);
-		while (!(bio->bio_flags & BIO_DONE))
-			pthread_cond_wait(&bio->bio_wait, &bio->bio_mutex);
-		pthread_mutex_unlock(&bio->bio_mutex);
-
-		destroy_bio(bio);
-
-	        uio->uio_iov++;
-        	uio->uio_iovcnt--;
-        	uio->uio_resid -= iov->iov_len;
-        	uio->uio_offset += iov->iov_len;
-	}
-
-	return 0;
-}
-

fs/vfs/vfs_bdev.c

+
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#include <osv/device.h>
+#include <osv/prex.h>
+#include <osv/buf.h>
+#include <osv/bio.h>
+
+int
+bdev_read(struct device *dev, struct uio *uio, int ioflags)
+{
+	struct buf *bp;
+	int ret;
+
+	assert(uio->uio_rw == UIO_READ);
+
+	/*
+	 * These should be handled gracefully, but this gives us the
+	 * best debugging for now.
+	 */
+	assert((uio->uio_offset % BSIZE) == 0);
+	assert((uio->uio_resid % BSIZE) == 0);
+
+	if (uio->uio_offset < 0)
+		return EINVAL;
+	if (uio->uio_resid == 0)
+		return 0;
+    
+	while (uio->uio_resid > 0) {
+		struct iovec *iov = uio->uio_iov;
+
+		if (!iov->iov_len)
+			continue;
+
+		ret = bread(dev, uio->uio_offset >> 9, &bp);
+		if (ret)
+			return ret;
+
+		ret = uiomove(bp->b_data, BSIZE, uio);
+		brelse(bp);
+
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int
+bdev_write(struct device *dev, struct uio *uio, int ioflags)
+{
+	struct buf *bp;
+	int ret;
+
+	assert(uio->uio_rw == UIO_WRITE);
+
+	/*
+	 * These should be handled gracefully, but this gives us the
+	 * best debugging for now.
+	 */
+	assert((uio->uio_offset % BSIZE) == 0);
+	assert((uio->uio_resid % BSIZE) == 0);
+
+	if (uio->uio_offset < 0)
+		return EINVAL;
+	if (uio->uio_resid == 0)
+		return 0;
+    
+	while (uio->uio_resid > 0) {
+		struct iovec *iov = uio->uio_iov;
+
+		if (!iov->iov_len)
+			continue;
+
+		bp = getblk(dev, uio->uio_offset >> 9);
+
+		ret = uiomove(bp->b_data, BSIZE, uio);
+		if (ret) {
+			brelse(bp);
+			return ret;
+		}
+
+		ret = bwrite(bp);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+
+int
+physio(struct device *dev, struct uio *uio, int ioflags)
+{
+	struct bio *bio;
+
+	if (uio->uio_offset < 0)
+		return EINVAL;
+	if (uio->uio_resid == 0)
+		return 0;
+    
+	while (uio->uio_resid > 0) {
+		struct iovec *iov = uio->uio_iov;
+
+		if (!iov->iov_len)
+			continue;
+
+		bio = alloc_bio();
+		if (!bio)
+			return ENOMEM;
+
+		if (uio->uio_rw == UIO_READ)
+			bio->bio_cmd = BIO_READ;
+		else
+			bio->bio_cmd = BIO_WRITE;
+
+		bio->bio_dev = dev;
+		bio->bio_data = iov->iov_base;
+		bio->bio_offset = uio->uio_offset;
+		bio->bio_bcount = uio->uio_resid;
+
+		dev->driver->devops->strategy(bio);
+
+		pthread_mutex_lock(&bio->bio_mutex);
+		while (!(bio->bio_flags & BIO_DONE))
+			pthread_cond_wait(&bio->bio_wait, &bio->bio_mutex);
+		pthread_mutex_unlock(&bio->bio_mutex);
+
+		destroy_bio(bio);
+
+	        uio->uio_iov++;
+        	uio->uio_iovcnt--;
+        	uio->uio_resid -= iov->iov_len;
+        	uio->uio_offset += iov->iov_len;
+	}
+
+	return 0;
+}

include/osv/device.h

@@ -128,6 +128,9 @@ int	 device_write(struct device *, struct uio *, int);
 int	 device_ioctl(struct device *, u_long, void *);
 int	 device_info(struct devinfo *);
 
+int	 bdev_read(struct device *dev, struct uio *uio, int ioflags);
+int	 bdev_write(struct device *dev, struct uio *uio, int ioflags);
+
 int	enodev(void);
 int	nullop(void);