1 files changed, 175 insertions, 144 deletions

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index bc458f57921b..49c047b75cc5 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -106,10 +106,15 @@ static inline void ubd_set_bit(__u64 bit, unsigned char *data)
 
 #define DRIVER_NAME "uml-blkdev"
 
+/* Can be taken in interrupt context, and is passed to the block layer to lock
+ * the request queue. Kernel side code knows that. */
 static DEFINE_SPINLOCK(ubd_io_lock);
-static DEFINE_SPINLOCK(ubd_lock);
 
-static void (*do_ubd)(void);
+static DEFINE_MUTEX(ubd_lock);
+
+/* XXX - this made sense in 2.4 days, now it's only used as a boolean, and
+ * probably it doesn't make sense even for that. */
+static int do_ubd;
 
 static int ubd_open(struct inode * inode, struct file * filp);
 static int ubd_release(struct inode * inode, struct file * file);
@@ -117,7 +122,7 @@ static int ubd_ioctl(struct inode * inode, struct file * file,
 		     unsigned int cmd, unsigned long arg);
 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
 
-#define MAX_DEV (8)
+#define MAX_DEV (16)
 
 static struct block_device_operations ubd_blops = {
         .owner		= THIS_MODULE,
@@ -150,8 +155,9 @@ static struct gendisk *fake_gendisk[MAX_DEV];
 static struct openflags global_openflags = OPEN_FLAGS;
 
 struct cow {
-	/* This is the backing file, actually */
+	/* backing file name */
 	char *file;
+	/* backing file fd */
 	int fd;
 	unsigned long *bitmap;
 	unsigned long bitmap_len;
@@ -160,14 +166,16 @@ struct cow {
 };
 
 struct ubd {
+	/* name (and fd, below) of the file opened for writing, either the
+	 * backing or the cow file. */
 	char *file;
 	int count;
 	int fd;
 	__u64 size;
 	struct openflags boot_openflags;
 	struct openflags openflags;
-	int shared;
-	int no_cow;
+	unsigned shared:1;
+	unsigned no_cow:1;
 	struct cow cow;
 	struct platform_device pdev;
 };
@@ -192,18 +200,7 @@ struct ubd {
         .cow =			DEFAULT_COW, \
 }
 
-struct ubd ubd_dev[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
-
-static int ubd0_init(void)
-{
-	struct ubd *dev = &ubd_dev[0];
-
-	if(dev->file == NULL)
-		dev->file = "root_fs";
-	return(0);
-}
-
-__initcall(ubd0_init);
+struct ubd ubd_devs[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
 
 /* Only changed by fake_ide_setup which is a setup */
 static int fake_ide = 0;
@@ -277,7 +274,7 @@ static int parse_unit(char **ptr)
 			return(-1);
 		*ptr = end;
 	}
-	else if (('a' <= *str) && (*str <= 'h')) {
+	else if (('a' <= *str) && (*str <= 'z')) {
 		n = *str - 'a';
 		str++;
 		*ptr = str;
@@ -285,9 +282,13 @@ static int parse_unit(char **ptr)
 	return(n);
 }
 
+/* If *index_out == -1 at exit, the passed option was a general one;
+ * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
+ * should not be freed on exit.
+ */
 static int ubd_setup_common(char *str, int *index_out)
 {
-	struct ubd *dev;
+	struct ubd *ubd_dev;
 	struct openflags flags = global_openflags;
 	char *backing_file;
 	int n, err, i;
@@ -311,7 +312,7 @@ static int ubd_setup_common(char *str, int *index_out)
 		}
 
 		err = 1;
- 		spin_lock(&ubd_lock);
+ 		mutex_lock(&ubd_lock);
  		if(fake_major != MAJOR_NR){
  			printk(KERN_ERR "Can't assign a fake major twice\n");
  			goto out1;
@@ -323,7 +324,7 @@ static int ubd_setup_common(char *str, int *index_out)
 		       major);
  		err = 0;
  	out1:
- 		spin_unlock(&ubd_lock);
+ 		mutex_unlock(&ubd_lock);
 		return(err);
 	}
 
@@ -340,10 +341,10 @@ static int ubd_setup_common(char *str, int *index_out)
 	}
 
 	err = 1;
-	spin_lock(&ubd_lock);
+	mutex_lock(&ubd_lock);
 
-	dev = &ubd_dev[n];
-	if(dev->file != NULL){
+	ubd_dev = &ubd_devs[n];
+	if(ubd_dev->file != NULL){
 		printk(KERN_ERR "ubd_setup : device already configured\n");
 		goto out;
 	}
@@ -360,10 +361,10 @@ static int ubd_setup_common(char *str, int *index_out)
 			flags.s = 1;
 			break;
 		case 'd':
-			dev->no_cow = 1;
+			ubd_dev->no_cow = 1;
 			break;
 		case 'c':
-			dev->shared = 1;
+			ubd_dev->shared = 1;
 			break;
 		case '=':
 			str++;
@@ -390,7 +391,7 @@ break_loop:
 	}
 
 	if(backing_file){
-		if(dev->no_cow)
+		if(ubd_dev->no_cow)
 			printk(KERN_ERR "Can't specify both 'd' and a "
 			       "cow file\n");
 		else {
@@ -398,11 +399,11 @@ break_loop:
 			backing_file++;
 		}
 	}
-	dev->file = str;
-	dev->cow.file = backing_file;
-	dev->boot_openflags = flags;
+	ubd_dev->file = str;
+	ubd_dev->cow.file = backing_file;
+	ubd_dev->boot_openflags = flags;
 out:
-	spin_unlock(&ubd_lock);
+	mutex_unlock(&ubd_lock);
 	return(err);
 }
 
@@ -472,8 +473,9 @@ int thread_fd = -1;
 
 /* Changed by ubd_handler, which is serialized because interrupts only
  * happen on CPU 0.
+ * XXX: currently unused.
  */
-int intr_count = 0;
+static int intr_count = 0;
 
 /* call ubd_finish if you need to serialize */
 static void __ubd_finish(struct request *req, int error)
@@ -493,6 +495,8 @@ static void __ubd_finish(struct request *req, int error)
 	end_request(req, 1);
 }
 
+/* Callable only from interrupt context - otherwise you need to do
+ * spin_lock_irq()/spin_lock_irqsave() */
 static inline void ubd_finish(struct request *req, int error)
 {
  	spin_lock(&ubd_io_lock);
@@ -500,14 +504,15 @@ static inline void ubd_finish(struct request *req, int error)
 	spin_unlock(&ubd_io_lock);
 }
 
-/* Called without ubd_io_lock held */
+/* XXX - move this inside ubd_intr. */
+/* Called without ubd_io_lock held, and only in interrupt context. */
 static void ubd_handler(void)
 {
 	struct io_thread_req req;
 	struct request *rq = elv_next_request(ubd_queue);
 	int n;
 
-	do_ubd = NULL;
+	do_ubd = 0;
 	intr_count++;
 	n = os_read_file(thread_fd, &req, sizeof(req));
 	if(n != sizeof(req)){
@@ -521,7 +526,9 @@ static void ubd_handler(void)
 
 	ubd_finish(rq, req.error);
 	reactivate_fd(thread_fd, UBD_IRQ);	
+	spin_lock(&ubd_io_lock);
 	do_ubd_request(ubd_queue);
+	spin_unlock(&ubd_io_lock);
 }
 
 static irqreturn_t ubd_intr(int irq, void *dev)
@@ -541,87 +548,90 @@ void kill_io_thread(void)
 
 __uml_exitcall(kill_io_thread);
 
-static int ubd_file_size(struct ubd *dev, __u64 *size_out)
+static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 {
 	char *file;
 
-	file = dev->cow.file ? dev->cow.file : dev->file;
+	file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
 	return(os_file_size(file, size_out));
 }
 
-static void ubd_close(struct ubd *dev)
+static void ubd_close_dev(struct ubd *ubd_dev)
 {
-	os_close_file(dev->fd);
-	if(dev->cow.file == NULL)
+	os_close_file(ubd_dev->fd);
+	if(ubd_dev->cow.file == NULL)
 		return;
 
-	os_close_file(dev->cow.fd);
-	vfree(dev->cow.bitmap);
-	dev->cow.bitmap = NULL;
+	os_close_file(ubd_dev->cow.fd);
+	vfree(ubd_dev->cow.bitmap);
+	ubd_dev->cow.bitmap = NULL;
 }
 
-static int ubd_open_dev(struct ubd *dev)
+static int ubd_open_dev(struct ubd *ubd_dev)
 {
 	struct openflags flags;
 	char **back_ptr;
 	int err, create_cow, *create_ptr;
+	int fd;
 
-	dev->openflags = dev->boot_openflags;
+	ubd_dev->openflags = ubd_dev->boot_openflags;
 	create_cow = 0;
-	create_ptr = (dev->cow.file != NULL) ? &create_cow : NULL;
-	back_ptr = dev->no_cow ? NULL : &dev->cow.file;
-	dev->fd = open_ubd_file(dev->file, &dev->openflags, dev->shared,
-				back_ptr, &dev->cow.bitmap_offset,
-				&dev->cow.bitmap_len, &dev->cow.data_offset,
+	create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
+	back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
+
+	fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
+				back_ptr, &ubd_dev->cow.bitmap_offset,
+				&ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
 				create_ptr);
 
-	if((dev->fd == -ENOENT) && create_cow){
-		dev->fd = create_cow_file(dev->file, dev->cow.file,
-					  dev->openflags, 1 << 9, PAGE_SIZE,
-					  &dev->cow.bitmap_offset,
-					  &dev->cow.bitmap_len,
-					  &dev->cow.data_offset);
-		if(dev->fd >= 0){
+	if((fd == -ENOENT) && create_cow){
+		fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
+					  ubd_dev->openflags, 1 << 9, PAGE_SIZE,
+					  &ubd_dev->cow.bitmap_offset,
+					  &ubd_dev->cow.bitmap_len,
+					  &ubd_dev->cow.data_offset);
+		if(fd >= 0){
 			printk(KERN_INFO "Creating \"%s\" as COW file for "
-			       "\"%s\"\n", dev->file, dev->cow.file);
+			       "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
 		}
 	}
 
-	if(dev->fd < 0){
-		printk("Failed to open '%s', errno = %d\n", dev->file,
-		       -dev->fd);
-		return(dev->fd);
+	if(fd < 0){
+		printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
+		       -fd);
+		return fd;
 	}
+	ubd_dev->fd = fd;
 
-	if(dev->cow.file != NULL){
+	if(ubd_dev->cow.file != NULL){
 		err = -ENOMEM;
-		dev->cow.bitmap = (void *) vmalloc(dev->cow.bitmap_len);
-		if(dev->cow.bitmap == NULL){
+		ubd_dev->cow.bitmap = (void *) vmalloc(ubd_dev->cow.bitmap_len);
+		if(ubd_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,
-				      dev->cow.bitmap_offset,
-				      dev->cow.bitmap_len);
+		err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
+				      ubd_dev->cow.bitmap_offset,
+				      ubd_dev->cow.bitmap_len);
 		if(err < 0)
 			goto error;
 
-		flags = dev->openflags;
+		flags = ubd_dev->openflags;
 		flags.w = 0;
-		err = open_ubd_file(dev->cow.file, &flags, dev->shared, NULL,
+		err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
 				    NULL, NULL, NULL, NULL);
 		if(err < 0) goto error;
-		dev->cow.fd = err;
+		ubd_dev->cow.fd = err;
 	}
 	return(0);
  error:
-	os_close_file(dev->fd);
+	os_close_file(ubd_dev->fd);
 	return(err);
 }
 
-static int ubd_new_disk(int major, u64 size, int unit,
+static int ubd_disk_register(int major, u64 size, int unit,
 			struct gendisk **disk_out)
 			
 {
@@ -642,13 +652,13 @@ static int ubd_new_disk(int major, u64 size, int unit,
 
 	/* sysfs register (not for ide fake devices) */
 	if (major == MAJOR_NR) {
-		ubd_dev[unit].pdev.id   = unit;
-		ubd_dev[unit].pdev.name = DRIVER_NAME;
-		platform_device_register(&ubd_dev[unit].pdev);
-		disk->driverfs_dev = &ubd_dev[unit].pdev.dev;
+		ubd_devs[unit].pdev.id   = unit;
+		ubd_devs[unit].pdev.name = DRIVER_NAME;
+		platform_device_register(&ubd_devs[unit].pdev);
+		disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
 	}
 
-	disk->private_data = &ubd_dev[unit];
+	disk->private_data = &ubd_devs[unit];
 	disk->queue = ubd_queue;
 	add_disk(disk);
 
@@ -660,25 +670,25 @@ static int ubd_new_disk(int major, u64 size, int unit,
 
 static int ubd_add(int n)
 {
-	struct ubd *dev = &ubd_dev[n];
+	struct ubd *ubd_dev = &ubd_devs[n];
 	int err;
 
 	err = -ENODEV;
-	if(dev->file == NULL)
+	if(ubd_dev->file == NULL)
 		goto out;
 
-	err = ubd_file_size(dev, &dev->size);
+	err = ubd_file_size(ubd_dev, &ubd_dev->size);
 	if(err < 0)
 		goto out;
 
-	dev->size = ROUND_BLOCK(dev->size);
+	ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 
-	err = ubd_new_disk(MAJOR_NR, dev->size, n, &ubd_gendisk[n]);
+	err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
 	if(err)
 		goto out;
 
 	if(fake_major != MAJOR_NR)
-		ubd_new_disk(fake_major, dev->size, n,
+		ubd_disk_register(fake_major, ubd_dev->size, n,
 			     &fake_gendisk[n]);
 
 	/* perhaps this should also be under the "if (fake_major)" above */
@@ -693,32 +703,41 @@ out:
 
 static int ubd_config(char *str)
 {
-	int n, err;
+	int n, ret;
 
 	str = kstrdup(str, GFP_KERNEL);
-	if(str == NULL){
+	if (str == NULL) {
 		printk(KERN_ERR "ubd_config failed to strdup string\n");
-		return(1);
+		ret = 1;
+		goto out;
 	}
-	err = ubd_setup_common(str, &n);
-	if(err){
-		kfree(str);
-		return(-1);
+	ret = ubd_setup_common(str, &n);
+	if (ret) {
+		ret = -1;
+		goto err_free;
+	}
+	if (n == -1) {
+		ret = 0;
+		goto err_free;
 	}
-	if(n == -1) return(0);
 
- 	spin_lock(&ubd_lock);
-	err = ubd_add(n);
-	if(err)
-		ubd_dev[n].file = NULL;
- 	spin_unlock(&ubd_lock);
+ 	mutex_lock(&ubd_lock);
+	ret = ubd_add(n);
+	if (ret)
+		ubd_devs[n].file = NULL;
+ 	mutex_unlock(&ubd_lock);
 
-	return(err);
+out:
+ 	return ret;
+
+err_free:
+	kfree(str);
+	goto out;
 }
 
 static int ubd_get_config(char *name, char *str, int size, char **error_out)
 {
-	struct ubd *dev;
+	struct ubd *ubd_dev;
 	int n, len = 0;
 
 	n = parse_unit(&name);
@@ -727,24 +746,24 @@ static int ubd_get_config(char *name, char *str, int size, char **error_out)
 		return(-1);
 	}
 
-	dev = &ubd_dev[n];
-	spin_lock(&ubd_lock);
+	ubd_dev = &ubd_devs[n];
+	mutex_lock(&ubd_lock);
 
-	if(dev->file == NULL){
+	if(ubd_dev->file == NULL){
 		CONFIG_CHUNK(str, size, len, "", 1);
 		goto out;
 	}
 
-	CONFIG_CHUNK(str, size, len, dev->file, 0);
+	CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
 
-	if(dev->cow.file != NULL){
+	if(ubd_dev->cow.file != NULL){
 		CONFIG_CHUNK(str, size, len, ",", 0);
-		CONFIG_CHUNK(str, size, len, dev->cow.file, 1);
+		CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
 	}
 	else CONFIG_CHUNK(str, size, len, "", 1);
 
  out:
-	spin_unlock(&ubd_lock);
+	mutex_unlock(&ubd_lock);
 	return(len);
 }
 
@@ -760,22 +779,22 @@ static int ubd_id(char **str, int *start_out, int *end_out)
 
 static int ubd_remove(int n)
 {
-	struct ubd *dev;
+	struct ubd *ubd_dev;
 	int err = -ENODEV;
 
-	spin_lock(&ubd_lock);
+	mutex_lock(&ubd_lock);
 
 	if(ubd_gendisk[n] == NULL)
 		goto out;
 
-	dev = &ubd_dev[n];
+	ubd_dev = &ubd_devs[n];
 
-	if(dev->file == NULL)
+	if(ubd_dev->file == NULL)
 		goto out;
 
 	/* you cannot remove a open disk */
 	err = -EBUSY;
-	if(dev->count > 0)
+	if(ubd_dev->count > 0)
 		goto out;
 
 	del_gendisk(ubd_gendisk[n]);
@@ -788,14 +807,15 @@ static int ubd_remove(int n)
 		fake_gendisk[n] = NULL;
 	}
 
-	platform_device_unregister(&dev->pdev);
-	*dev = ((struct ubd) DEFAULT_UBD);
+	platform_device_unregister(&ubd_dev->pdev);
+	*ubd_dev = ((struct ubd) DEFAULT_UBD);
 	err = 0;
 out:
-	spin_unlock(&ubd_lock);
+	mutex_unlock(&ubd_lock);
 	return err;
 }
 
+/* All these are called by mconsole in process context and without ubd-specific locks. */
 static struct mc_device ubd_mc = {
 	.name		= "ubd",
 	.config		= ubd_config,
@@ -804,7 +824,7 @@ static struct mc_device ubd_mc = {
 	.remove		= ubd_remove,
 };
 
-static int ubd_mc_init(void)
+static int __init ubd_mc_init(void)
 {
 	mconsole_register_dev(&ubd_mc);
 	return 0;
@@ -812,13 +832,24 @@ static int ubd_mc_init(void)
 
 __initcall(ubd_mc_init);
 
+static int __init ubd0_init(void)
+{
+	struct ubd *ubd_dev = &ubd_devs[0];
+
+	if(ubd_dev->file == NULL)
+		ubd_dev->file = "root_fs";
+	return(0);
+}
+
+__initcall(ubd0_init);
+
 static struct platform_driver ubd_driver = {
 	.driver = {
 		.name  = DRIVER_NAME,
 	},
 };
 
-int ubd_init(void)
+static int __init ubd_init(void)
 {
         int i;
 
@@ -846,7 +877,7 @@ int ubd_init(void)
 
 late_initcall(ubd_init);
 
-int ubd_driver_init(void){
+static int __init ubd_driver_init(void){
 	unsigned long stack;
 	int err;
 
@@ -867,7 +898,7 @@ int ubd_driver_init(void){
 		return(0);
 	}
 	err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
-			     IRQF_DISABLED, "ubd", ubd_dev);
+			     IRQF_DISABLED, "ubd", ubd_devs);
 	if(err != 0)
 		printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
 	return 0;
@@ -878,24 +909,24 @@ device_initcall(ubd_driver_init);
 static int ubd_open(struct inode *inode, struct file *filp)
 {
 	struct gendisk *disk = inode->i_bdev->bd_disk;
-	struct ubd *dev = disk->private_data;
+	struct ubd *ubd_dev = disk->private_data;
 	int err = 0;
 
-	if(dev->count == 0){
-		err = ubd_open_dev(dev);
+	if(ubd_dev->count == 0){
+		err = ubd_open_dev(ubd_dev);
 		if(err){
 			printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
-			       disk->disk_name, dev->file, -err);
+			       disk->disk_name, ubd_dev->file, -err);
 			goto out;
 		}
 	}
-	dev->count++;
-	set_disk_ro(disk, !dev->openflags.w);
+	ubd_dev->count++;
+	set_disk_ro(disk, !ubd_dev->openflags.w);
 
 	/* This should no more be needed. And it didn't work anyway to exclude
 	 * read-write remounting of filesystems.*/
-	/*if((filp->f_mode & FMODE_WRITE) && !dev->openflags.w){
-	        if(--dev->count == 0) ubd_close(dev);
+	/*if((filp->f_mode & FMODE_WRITE) && !ubd_dev->openflags.w){
+	        if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
 	        err = -EROFS;
 	}*/
  out:
@@ -905,10 +936,10 @@ static int ubd_open(struct inode *inode, struct file *filp)
 static int ubd_release(struct inode * inode, struct file * file)
 {
 	struct gendisk *disk = inode->i_bdev->bd_disk;
-	struct ubd *dev = disk->private_data;
+	struct ubd *ubd_dev = disk->private_data;
 
-	if(--dev->count == 0)
-		ubd_close(dev);
+	if(--ubd_dev->count == 0)
+		ubd_close_dev(ubd_dev);
 	return(0);
 }
 
@@ -976,12 +1007,12 @@ static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
 static int prepare_request(struct request *req, struct io_thread_req *io_req)
 {
 	struct gendisk *disk = req->rq_disk;
-	struct ubd *dev = disk->private_data;
+	struct ubd *ubd_dev = disk->private_data;
 	__u64 offset;
 	int len;
 
 	/* This should be impossible now */
-	if((rq_data_dir(req) == WRITE) && !dev->openflags.w){
+	if((rq_data_dir(req) == WRITE) && !ubd_dev->openflags.w){
 		printk("Write attempted on readonly ubd device %s\n",
 		       disk->disk_name);
 		end_request(req, 0);
@@ -991,8 +1022,8 @@ static int prepare_request(struct request *req, struct io_thread_req *io_req)
 	offset = ((__u64) req->sector) << 9;
 	len = req->current_nr_sectors << 9;
 
-	io_req->fds[0] = (dev->cow.file != NULL) ? dev->cow.fd : dev->fd;
-	io_req->fds[1] = dev->fd;
+	io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd : ubd_dev->fd;
+	io_req->fds[1] = ubd_dev->fd;
 	io_req->cow_offset = -1;
 	io_req->offset = offset;
 	io_req->length = len;
@@ -1001,13 +1032,13 @@ static int prepare_request(struct request *req, struct io_thread_req *io_req)
 
 	io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
 	io_req->offsets[0] = 0;
-	io_req->offsets[1] = dev->cow.data_offset;
+	io_req->offsets[1] = ubd_dev->cow.data_offset;
 	io_req->buffer = req->buffer;
 	io_req->sectorsize = 1 << 9;
 
-	if(dev->cow.file != NULL)
-		cowify_req(io_req, dev->cow.bitmap, dev->cow.bitmap_offset,
-			   dev->cow.bitmap_len);
+	if(ubd_dev->cow.file != NULL)
+		cowify_req(io_req, ubd_dev->cow.bitmap, ubd_dev->cow.bitmap_offset,
+			   ubd_dev->cow.bitmap_len);
 
 	return(0);
 }
@@ -1033,7 +1064,7 @@ static void do_ubd_request(request_queue_t *q)
 			return;
 		err = prepare_request(req, &io_req);
 		if(!err){
-			do_ubd = ubd_handler;
+			do_ubd = 1;
 			n = os_write_file(thread_fd, (char *) &io_req,
 					 sizeof(io_req));
 			if(n != sizeof(io_req))
@@ -1045,18 +1076,18 @@ static void do_ubd_request(request_queue_t *q)
 
 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
-	struct ubd *dev = bdev->bd_disk->private_data;
+	struct ubd *ubd_dev = bdev->bd_disk->private_data;
 
 	geo->heads = 128;
 	geo->sectors = 32;
-	geo->cylinders = dev->size / (128 * 32 * 512);
+	geo->cylinders = ubd_dev->size / (128 * 32 * 512);
 	return 0;
 }
 
 static int ubd_ioctl(struct inode * inode, struct file * file,
 		     unsigned int cmd, unsigned long arg)
 {
-	struct ubd *dev = inode->i_bdev->bd_disk->private_data;
+	struct ubd *ubd_dev = inode->i_bdev->bd_disk->private_data;
 	struct hd_driveid ubd_id = {
 		.cyls		= 0,
 		.heads		= 128,
@@ -1066,7 +1097,7 @@ static int ubd_ioctl(struct inode * inode, struct file * file,
 	switch (cmd) {
 		struct cdrom_volctrl volume;
 	case HDIO_GET_IDENTITY:
-		ubd_id.cyls = dev->size / (128 * 32 * 512);
+		ubd_id.cyls = ubd_dev->size / (128 * 32 * 512);
 		if(copy_to_user((char __user *) arg, (char *) &ubd_id,
 				 sizeof(ubd_id)))
 			return(-EFAULT);
@@ -1353,8 +1384,8 @@ void do_io(struct io_thread_req *req)
  */
 int kernel_fd = -1;
 
-/* Only changed by the io thread */
-int io_count = 0;
+/* Only changed by the io thread. XXX: currently unused. */
+static int io_count = 0;
 
 int io_thread(void *arg)
 {