Added a 'd' option, which makes a device that looks like a COW file to be

treated as normal data.

1 files changed, 23 insertions, 6 deletions

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index ecd3040..0e65792 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -132,6 +132,7 @@ struct ubd {
 	struct openflags boot_openflags;
 	struct openflags openflags;
 	devfs_handle_t devfs;
+	int no_cow;
 	struct cow cow;
 };
 
@@ -151,6 +152,7 @@ struct ubd {
 	.boot_openflags		= OPEN_FLAGS, \
 	.openflags		= OPEN_FLAGS, \
 	.devfs			= NULL, \
+	.no_cow			= 0, \
         .cow			= DEFAULT_COW, \
 }
 
@@ -322,14 +324,19 @@ static int ubd_setup_common(char *str, int *index_out)
 
 	if(index_out) *index_out = n;
 
-	if (*str == 'r'){
+	if(*str == 'r'){
 		flags.w = 0;
 		str++;
 	}
-	if (*str == 's'){
+	if(*str == 's'){
 		flags.s = 1;
 		str++;
 	}
+	if(*str == 'd'){
+		dev->no_cow = 1;
+		str++;
+	}
+
 	if(*str++ != '='){
 		printk(KERN_ERR "ubd_setup : Expected '='\n");
 		goto out2;
@@ -338,8 +345,13 @@ static int ubd_setup_common(char *str, int *index_out)
 	err = 0;
 	backing_file = strchr(str, ',');
 	if(backing_file){
-		*backing_file = '\0';
-		backing_file++;
+		if(dev->no_cow)
+			printk(KERN_ERR "Can't specify both 'd' and a "
+			       "cow file\n");
+		else {
+			*backing_file = '\0';
+			backing_file++;
+		}
 	}
 	dev->file = str;
 	dev->cow.file = backing_file;
@@ -692,12 +704,14 @@ static void ubd_close(struct ubd *dev)
 static int ubd_open_dev(struct ubd *dev)
 {
 	struct openflags flags;
+	char **back_ptr;
 	int err, create_cow, *create_ptr;
 
 	dev->openflags = dev->boot_openflags;
 	create_cow = 0;
 	create_ptr = (dev->cow.file != NULL) ? &create_cow : NULL;
-	dev->fd = open_ubd_file(dev->file, &dev->openflags, &dev->cow.file,
+	back_ptr = dev->no_cow ? NULL : &dev->cow.file;
+	dev->fd = open_ubd_file(dev->file, &dev->openflags, back_ptr,
 				&dev->cow.bitmap_offset, &dev->cow.bitmap_len, 
 				&dev->cow.data_offset, create_ptr);
 
@@ -718,7 +732,10 @@ static int ubd_open_dev(struct ubd *dev)
 	if(dev->cow.file != NULL){
 		err = -ENOMEM;
 		dev->cow.bitmap = (void *) vmalloc(dev->cow.bitmap_len);
-		if(dev->cow.bitmap == NULL) goto error;
+		if(dev->cow.bitmap == NULL){
+			printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
+			goto error;
+		}
 		flush_tlb_kernel_vm();
 
 		err = read_cow_bitmap(dev->fd, dev->cow.bitmap,