1 files changed, 195 insertions, 156 deletions

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 8bd9204ac1a..70509ddaac0 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -39,7 +39,6 @@
 #include "asm/irq.h"
 #include "asm/types.h"
 #include "asm/tlbflush.h"
-#include "user_util.h"
 #include "mem_user.h"
 #include "kern_util.h"
 #include "kern.h"
@@ -90,7 +89,7 @@ static inline int ubd_test_bit(__u64 bit, unsigned char *data)
 	bits = sizeof(data[0]) * 8;
 	n = bit / bits;
 	off = bit % bits;
-	return((data[n] & (1 << off)) != 0);
+	return (data[n] & (1 << off)) != 0;
 }
 
 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
@@ -147,10 +146,13 @@ struct cow {
 	unsigned long *bitmap;
 	unsigned long bitmap_len;
 	int bitmap_offset;
-        int data_offset;
+	int data_offset;
 };
 
+#define MAX_SG 64
+
 struct ubd {
+	struct list_head restart;
 	/* name (and fd, below) of the file opened for writing, either the
 	 * backing or the cow file. */
 	char *file;
@@ -165,15 +167,17 @@ struct ubd {
 	struct platform_device pdev;
 	struct request_queue *queue;
 	spinlock_t lock;
-	int active;
+	struct scatterlist sg[MAX_SG];
+	struct request *request;
+	int start_sg, end_sg;
 };
 
 #define DEFAULT_COW { \
 	.file =			NULL, \
-        .fd =			-1, \
-        .bitmap =		NULL, \
+	.fd =			-1,	\
+	.bitmap =		NULL, \
 	.bitmap_offset =	0, \
-        .data_offset =		0, \
+	.data_offset =		0, \
 }
 
 #define DEFAULT_UBD { \
@@ -183,11 +187,13 @@ struct ubd {
 	.size =			-1, \
 	.boot_openflags =	OPEN_FLAGS, \
 	.openflags =		OPEN_FLAGS, \
-        .no_cow =               0, \
+	.no_cow =               0, \
 	.shared =		0, \
-        .cow =			DEFAULT_COW, \
+	.cow =			DEFAULT_COW, \
 	.lock =			SPIN_LOCK_UNLOCKED,	\
-	.active =		0, \
+	.request =		NULL, \
+	.start_sg =		0, \
+	.end_sg =		0, \
 }
 
 /* Protected by ubd_lock */
@@ -243,7 +249,7 @@ static void make_ide_entries(char *dev_name)
 static int fake_ide_setup(char *str)
 {
 	fake_ide = 1;
-	return(1);
+	return 1;
 }
 
 __setup("fake_ide", fake_ide_setup);
@@ -261,7 +267,7 @@ static int parse_unit(char **ptr)
 	if(isdigit(*str)) {
 		n = simple_strtoul(str, &end, 0);
 		if(end == str)
-			return(-1);
+			return -1;
 		*ptr = end;
 	}
 	else if (('a' <= *str) && (*str <= 'z')) {
@@ -269,7 +275,7 @@ static int parse_unit(char **ptr)
 		str++;
 		*ptr = str;
 	}
-	return(n);
+	return n;
 }
 
 /* If *index_out == -1 at exit, the passed option was a general one;
@@ -436,7 +442,7 @@ static int udb_setup(char *str)
 {
 	printk("udb%s specified on command line is almost certainly a ubd -> "
 	       "udb TYPO\n", str);
-	return(1);
+	return 1;
 }
 
 __setup("udb", udb_setup);
@@ -467,66 +473,75 @@ static void do_ubd_request(request_queue_t * q);
 /* Only changed by ubd_init, which is an initcall. */
 int thread_fd = -1;
 
-/* call ubd_finish if you need to serialize */
-static void __ubd_finish(struct request *req, int error)
+static void ubd_end_request(struct request *req, int bytes, int uptodate)
 {
-	int nsect;
-
-	if(error){
-		end_request(req, 0);
-		return;
+	if (!end_that_request_first(req, uptodate, bytes >> 9)) {
+		struct ubd *dev = req->rq_disk->private_data;
+		unsigned long flags;
+
+		add_disk_randomness(req->rq_disk);
+		spin_lock_irqsave(&dev->lock, flags);
+		end_that_request_last(req, uptodate);
+		spin_unlock_irqrestore(&dev->lock, flags);
 	}
-	nsect = req->current_nr_sectors;
-	req->sector += nsect;
-	req->buffer += nsect << 9;
-	req->errors = 0;
-	req->nr_sectors -= nsect;
-	req->current_nr_sectors = 0;
-	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)
+static inline void ubd_finish(struct request *req, int bytes)
 {
-	struct ubd *dev = req->rq_disk->private_data;
-
-	spin_lock(&dev->lock);
-	__ubd_finish(req, error);
-	spin_unlock(&dev->lock);
+	if(bytes < 0){
+		ubd_end_request(req, 0, 0);
+		return;
+	}
+	ubd_end_request(req, bytes, 1);
 }
 
+static LIST_HEAD(restart);
+
 /* XXX - move this inside ubd_intr. */
 /* Called without dev->lock held, and only in interrupt context. */
 static void ubd_handler(void)
 {
-	struct io_thread_req req;
+	struct io_thread_req *req;
 	struct request *rq;
-	struct ubd *dev;
+	struct ubd *ubd;
+	struct list_head *list, *next_ele;
+	unsigned long flags;
 	int n;
 
-	n = os_read_file(thread_fd, &req, sizeof(req));
-	if(n != sizeof(req)){
-		printk(KERN_ERR "Pid %d - spurious interrupt in ubd_handler, "
-		       "err = %d\n", os_getpid(), -n);
-		return;
-	}
-
-	rq = req.req;
-	dev = rq->rq_disk->private_data;
-	dev->active = 0;
+	while(1){
+		n = os_read_file(thread_fd, &req,
+				 sizeof(struct io_thread_req *));
+		if(n != sizeof(req)){
+			if(n == -EAGAIN)
+				break;
+			printk(KERN_ERR "spurious interrupt in ubd_handler, "
+			       "err = %d\n", -n);
+			return;
+		}
 
-	ubd_finish(rq, req.error);
+		rq = req->req;
+		rq->nr_sectors -= req->length >> 9;
+		if(rq->nr_sectors == 0)
+			ubd_finish(rq, rq->hard_nr_sectors << 9);
+		kfree(req);
+	}
 	reactivate_fd(thread_fd, UBD_IRQ);
-	spin_lock(&dev->lock);
-	do_ubd_request(dev->queue);
-	spin_unlock(&dev->lock);
+
+	list_for_each_safe(list, next_ele, &restart){
+		ubd = container_of(list, struct ubd, restart);
+		list_del_init(&ubd->restart);
+		spin_lock_irqsave(&ubd->lock, flags);
+		do_ubd_request(ubd->queue);
+		spin_unlock_irqrestore(&ubd->lock, flags);
+	}
 }
 
 static irqreturn_t ubd_intr(int irq, void *dev)
 {
 	ubd_handler();
-	return(IRQ_HANDLED);
+	return IRQ_HANDLED;
 }
 
 /* Only changed by ubd_init, which is an initcall. */
@@ -545,7 +560,7 @@ static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 	char *file;
 
 	file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
-	return(os_file_size(file, size_out));
+	return os_file_size(file, size_out);
 }
 
 static void ubd_close_dev(struct ubd *ubd_dev)
@@ -617,10 +632,18 @@ static int ubd_open_dev(struct ubd *ubd_dev)
 		if(err < 0) goto error;
 		ubd_dev->cow.fd = err;
 	}
-	return(0);
+	return 0;
  error:
 	os_close_file(ubd_dev->fd);
-	return(err);
+	return err;
+}
+
+static void ubd_device_release(struct device *dev)
+{
+	struct ubd *ubd_dev = dev->driver_data;
+
+	blk_cleanup_queue(ubd_dev->queue);
+	*ubd_dev = ((struct ubd) DEFAULT_UBD);
 }
 
 static int ubd_disk_register(int major, u64 size, int unit,
@@ -630,7 +653,7 @@ static int ubd_disk_register(int major, u64 size, int unit,
 
 	disk = alloc_disk(1 << UBD_SHIFT);
 	if(disk == NULL)
-		return(-ENOMEM);
+		return -ENOMEM;
 
 	disk->major = major;
 	disk->first_minor = unit << UBD_SHIFT;
@@ -645,6 +668,8 @@ static int ubd_disk_register(int major, u64 size, int unit,
 	if (major == MAJOR_NR) {
 		ubd_devs[unit].pdev.id   = unit;
 		ubd_devs[unit].pdev.name = DRIVER_NAME;
+		ubd_devs[unit].pdev.dev.release = ubd_device_release;
+		ubd_devs[unit].pdev.dev.driver_data = &ubd_devs[unit];
 		platform_device_register(&ubd_devs[unit].pdev);
 		disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
 	}
@@ -675,6 +700,8 @@ static int ubd_add(int n, char **error_out)
 
 	ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 
+	INIT_LIST_HEAD(&ubd_dev->restart);
+
 	err = -ENOMEM;
 	ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
 	if (ubd_dev->queue == NULL) {
@@ -683,6 +710,7 @@ static int ubd_add(int n, char **error_out)
 	}
 	ubd_dev->queue->queuedata = ubd_dev;
 
+	blk_queue_max_hw_segments(ubd_dev->queue, MAX_SG);
 	err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
 	if(err){
 		*error_out = "Failed to register device";
@@ -730,14 +758,14 @@ static int ubd_config(char *str, char **error_out)
 		goto err_free;
 	}
 
- 	mutex_lock(&ubd_lock);
+	mutex_lock(&ubd_lock);
 	ret = ubd_add(n, error_out);
 	if (ret)
 		ubd_devs[n].file = NULL;
- 	mutex_unlock(&ubd_lock);
+	mutex_unlock(&ubd_lock);
 
 out:
- 	return ret;
+	return ret;
 
 err_free:
 	kfree(str);
@@ -752,7 +780,7 @@ static int ubd_get_config(char *name, char *str, int size, char **error_out)
 	n = parse_unit(&name);
 	if((n >= MAX_DEV) || (n < 0)){
 		*error_out = "ubd_get_config : device number out of range";
-		return(-1);
+		return -1;
 	}
 
 	ubd_dev = &ubd_devs[n];
@@ -773,29 +801,27 @@ static int ubd_get_config(char *name, char *str, int size, char **error_out)
 
  out:
 	mutex_unlock(&ubd_lock);
-	return(len);
+	return len;
 }
 
 static int ubd_id(char **str, int *start_out, int *end_out)
 {
-        int n;
+	int n;
 
 	n = parse_unit(str);
-        *start_out = 0;
-        *end_out = MAX_DEV - 1;
-        return n;
+	*start_out = 0;
+	*end_out = MAX_DEV - 1;
+	return n;
 }
 
 static int ubd_remove(int n, char **error_out)
 {
+	struct gendisk *disk = ubd_gendisk[n];
 	struct ubd *ubd_dev;
 	int err = -ENODEV;
 
 	mutex_lock(&ubd_lock);
 
-	if(ubd_gendisk[n] == NULL)
-		goto out;
-
 	ubd_dev = &ubd_devs[n];
 
 	if(ubd_dev->file == NULL)
@@ -806,9 +832,11 @@ static int ubd_remove(int n, char **error_out)
 	if(ubd_dev->count > 0)
 		goto out;
 
-	del_gendisk(ubd_gendisk[n]);
-	put_disk(ubd_gendisk[n]);
 	ubd_gendisk[n] = NULL;
+	if(disk != NULL){
+		del_gendisk(disk);
+		put_disk(disk);
+	}
 
 	if(fake_gendisk[n] != NULL){
 		del_gendisk(fake_gendisk[n]);
@@ -816,10 +844,8 @@ static int ubd_remove(int n, char **error_out)
 		fake_gendisk[n] = NULL;
 	}
 
-	blk_cleanup_queue(ubd_dev->queue);
-	platform_device_unregister(&ubd_dev->pdev);
-	*ubd_dev = ((struct ubd) DEFAULT_UBD);
 	err = 0;
+	platform_device_unregister(&ubd_dev->pdev);
 out:
 	mutex_unlock(&ubd_lock);
 	return err;
@@ -832,7 +858,7 @@ static struct mc_device ubd_mc = {
 	.list		= LIST_HEAD_INIT(ubd_mc.list),
 	.name		= "ubd",
 	.config		= ubd_config,
- 	.get_config	= ubd_get_config,
+	.get_config	= ubd_get_config,
 	.id		= ubd_id,
 	.remove		= ubd_remove,
 };
@@ -854,7 +880,7 @@ static int __init ubd0_init(void)
 		ubd_dev->file = "root_fs";
 	mutex_unlock(&ubd_lock);
 
-	return(0);
+	return 0;
 }
 
 __initcall(ubd0_init);
@@ -882,14 +908,14 @@ static int __init ubd_init(void)
 			return -1;
 	}
 	platform_driver_register(&ubd_driver);
- 	mutex_lock(&ubd_lock);
+	mutex_lock(&ubd_lock);
 	for (i = 0; i < MAX_DEV; i++){
 		err = ubd_add(i, &error);
 		if(err)
 			printk(KERN_ERR "Failed to initialize ubd device %d :"
 			       "%s\n", i, error);
 	}
- 	mutex_unlock(&ubd_lock);
+	mutex_unlock(&ubd_lock);
 	return 0;
 }
 
@@ -913,7 +939,7 @@ static int __init ubd_driver_init(void){
 		       "ubd : Failed to start I/O thread (errno = %d) - "
 		       "falling back to synchronous I/O\n", -io_pid);
 		io_pid = -1;
-		return(0);
+		return 0;
 	}
 	err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
 			     IRQF_DISABLED, "ubd", ubd_devs);
@@ -948,7 +974,7 @@ static int ubd_open(struct inode *inode, struct file *filp)
 	        err = -EROFS;
 	}*/
  out:
-	return(err);
+	return err;
 }
 
 static int ubd_release(struct inode * inode, struct file * file)
@@ -958,7 +984,7 @@ static int ubd_release(struct inode * inode, struct file * file)
 
 	if(--ubd_dev->count == 0)
 		ubd_close_dev(ubd_dev);
-	return(0);
+	return 0;
 }
 
 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
@@ -1014,7 +1040,7 @@ static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
 			if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
 				ubd_set_bit(i, (unsigned char *)
 					    &req->sector_mask);
-                }
+		}
 	}
 	else cowify_bitmap(req->offset, req->length, &req->sector_mask,
 			   &req->cow_offset, bitmap, bitmap_offset,
@@ -1022,26 +1048,16 @@ static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
 }
 
 /* Called with dev->lock held */
-static int prepare_request(struct request *req, struct io_thread_req *io_req)
+static void prepare_request(struct request *req, struct io_thread_req *io_req,
+			    unsigned long long offset, int page_offset,
+			    int len, struct page *page)
 {
 	struct gendisk *disk = req->rq_disk;
 	struct ubd *ubd_dev = disk->private_data;
-	__u64 offset;
-	int len;
-
-	/* This should be impossible now */
-	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);
-		return(1);
-	}
-
-	offset = ((__u64) req->sector) << 9;
-	len = req->current_nr_sectors << 9;
 
 	io_req->req = req;
-	io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd : ubd_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;
@@ -1052,45 +1068,66 @@ 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] = ubd_dev->cow.data_offset;
-	io_req->buffer = req->buffer;
+	io_req->buffer = page_address(page) + page_offset;
 	io_req->sectorsize = 1 << 9;
 
 	if(ubd_dev->cow.file != NULL)
-		cowify_req(io_req, ubd_dev->cow.bitmap, ubd_dev->cow.bitmap_offset,
-			   ubd_dev->cow.bitmap_len);
+		cowify_req(io_req, ubd_dev->cow.bitmap,
+			   ubd_dev->cow.bitmap_offset, ubd_dev->cow.bitmap_len);
 
-	return(0);
 }
 
 /* Called with dev->lock held */
 static void do_ubd_request(request_queue_t *q)
 {
-	struct io_thread_req io_req;
+	struct io_thread_req *io_req;
 	struct request *req;
-	int err, n;
-
-	if(thread_fd == -1){
-		while((req = elv_next_request(q)) != NULL){
-			err = prepare_request(req, &io_req);
-			if(!err){
-				do_io(&io_req);
-				__ubd_finish(req, io_req.error);
-			}
-		}
-	}
-	else {
+	int n;
+
+	while(1){
 		struct ubd *dev = q->queuedata;
-		if(dev->active || (req = elv_next_request(q)) == NULL)
-			return;
-		err = prepare_request(req, &io_req);
-		if(!err){
-			dev->active = 1;
-			n = os_write_file(thread_fd, (char *) &io_req,
-					 sizeof(io_req));
-			if(n != sizeof(io_req))
-				printk("write to io thread failed, "
-				       "errno = %d\n", -n);
+		if(dev->end_sg == 0){
+			struct request *req = elv_next_request(q);
+			if(req == NULL)
+				return;
+
+			dev->request = req;
+			blkdev_dequeue_request(req);
+			dev->start_sg = 0;
+			dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
 		}
+
+		req = dev->request;
+		while(dev->start_sg < dev->end_sg){
+			struct scatterlist *sg = &dev->sg[dev->start_sg];
+
+			io_req = kmalloc(sizeof(struct io_thread_req),
+					 GFP_ATOMIC);
+			if(io_req == NULL){
+				if(list_empty(&dev->restart))
+					list_add(&dev->restart, &restart);
+				return;
+			}
+			prepare_request(req, io_req,
+					(unsigned long long) req->sector << 9,
+					sg->offset, sg->length, sg->page);
+
+			n = os_write_file(thread_fd, &io_req,
+					  sizeof(struct io_thread_req *));
+			if(n != sizeof(struct io_thread_req *)){
+				if(n != -EAGAIN)
+					printk("write to io thread failed, "
+					       "errno = %d\n", -n);
+				else if(list_empty(&dev->restart))
+					list_add(&dev->restart, &restart);
+				return;
+			}
+
+			req->sector += sg->length >> 9;
+			dev->start_sg++;
+		}
+		dev->end_sg = 0;
+		dev->request = NULL;
 	}
 }
 
@@ -1120,21 +1157,21 @@ static int ubd_ioctl(struct inode * inode, struct file * file,
 		ubd_id.cyls = ubd_dev->size / (128 * 32 * 512);
 		if(copy_to_user((char __user *) arg, (char *) &ubd_id,
 				 sizeof(ubd_id)))
-			return(-EFAULT);
-		return(0);
+			return -EFAULT;
+		return 0;
 
 	case CDROMVOLREAD:
 		if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
-			return(-EFAULT);
+			return -EFAULT;
 		volume.channel0 = 255;
 		volume.channel1 = 255;
 		volume.channel2 = 255;
 		volume.channel3 = 255;
 		if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
-			return(-EFAULT);
-		return(0);
+			return -EFAULT;
+		return 0;
 	}
-	return(-EINVAL);
+	return -EINVAL;
 }
 
 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
@@ -1176,29 +1213,29 @@ static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
 	if(err < 0){
 		printk("Failed to get modification time of backing file "
 		       "\"%s\", err = %d\n", file, -err);
-		return(err);
+		return err;
 	}
 
 	err = os_file_size(file, &actual);
 	if(err < 0){
 		printk("Failed to get size of backing file \"%s\", "
 		       "err = %d\n", file, -err);
-		return(err);
+		return err;
 	}
 
-  	if(actual != size){
+	if(actual != size){
 		/*__u64 can be a long on AMD64 and with %lu GCC complains; so
 		 * the typecast.*/
 		printk("Size mismatch (%llu vs %llu) of COW header vs backing "
 		       "file\n", (unsigned long long) size, actual);
-		return(-EINVAL);
+		return -EINVAL;
 	}
 	if(modtime != mtime){
 		printk("mtime mismatch (%ld vs %ld) of COW header vs backing "
 		       "file\n", mtime, modtime);
-		return(-EINVAL);
+		return -EINVAL;
 	}
-	return(0);
+	return 0;
 }
 
 int read_cow_bitmap(int fd, void *buf, int offset, int len)
@@ -1207,13 +1244,13 @@ int read_cow_bitmap(int fd, void *buf, int offset, int len)
 
 	err = os_seek_file(fd, offset);
 	if(err < 0)
-		return(err);
+		return err;
 
 	err = os_read_file(fd, buf, len);
 	if(err < 0)
-		return(err);
+		return err;
 
-	return(0);
+	return 0;
 }
 
 int open_ubd_file(char *file, struct openflags *openflags, int shared,
@@ -1231,14 +1268,14 @@ int open_ubd_file(char *file, struct openflags *openflags, int shared,
 	if (fd < 0) {
 		if ((fd == -ENOENT) && (create_cow_out != NULL))
 			*create_cow_out = 1;
-                if (!openflags->w ||
-                   ((fd != -EROFS) && (fd != -EACCES)))
+		if (!openflags->w ||
+		    ((fd != -EROFS) && (fd != -EACCES)))
 			return fd;
 		openflags->w = 0;
 		fd = os_open_file(file, *openflags, mode);
 		if (fd < 0)
 			return fd;
-        }
+	}
 
 	if(shared)
 		printk("Not locking \"%s\" on the host\n", file);
@@ -1252,7 +1289,7 @@ int open_ubd_file(char *file, struct openflags *openflags, int shared,
 
 	/* Successful return case! */
 	if(backing_file_out == NULL)
-		return(fd);
+		return fd;
 
 	err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
 			      &size, &sectorsize, &align, bitmap_offset_out);
@@ -1262,7 +1299,7 @@ int open_ubd_file(char *file, struct openflags *openflags, int shared,
 		goto out_close;
 	}
 	if(err)
-		return(fd);
+		return fd;
 
 	asked_switch = path_requires_switch(*backing_file_out, backing_file, file);
 
@@ -1285,7 +1322,7 @@ int open_ubd_file(char *file, struct openflags *openflags, int shared,
 	cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
 		  bitmap_len_out, data_offset_out);
 
-        return fd;
+	return fd;
  out_close:
 	os_close_file(fd);
 	return err;
@@ -1310,10 +1347,10 @@ int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
 			    bitmap_offset_out, bitmap_len_out,
 			    data_offset_out);
 	if(!err)
-		return(fd);
+		return fd;
 	os_close_file(fd);
  out:
-	return(err);
+	return err;
 }
 
 static int update_bitmap(struct io_thread_req *req)
@@ -1321,23 +1358,23 @@ static int update_bitmap(struct io_thread_req *req)
 	int n;
 
 	if(req->cow_offset == -1)
-		return(0);
+		return 0;
 
 	n = os_seek_file(req->fds[1], req->cow_offset);
 	if(n < 0){
 		printk("do_io - bitmap lseek failed : err = %d\n", -n);
-		return(1);
+		return 1;
 	}
 
 	n = os_write_file(req->fds[1], &req->bitmap_words,
-		          sizeof(req->bitmap_words));
+			  sizeof(req->bitmap_words));
 	if(n != sizeof(req->bitmap_words)){
 		printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
 		       req->fds[1]);
-		return(1);
+		return 1;
 	}
 
-	return(0);
+	return 0;
 }
 
 void do_io(struct io_thread_req *req)
@@ -1409,13 +1446,14 @@ static int io_count = 0;
 
 int io_thread(void *arg)
 {
-	struct io_thread_req req;
+	struct io_thread_req *req;
 	int n;
 
 	ignore_sigwinch_sig();
 	while(1){
-		n = os_read_file(kernel_fd, &req, sizeof(req));
-		if(n != sizeof(req)){
+		n = os_read_file(kernel_fd, &req,
+				 sizeof(struct io_thread_req *));
+		if(n != sizeof(struct io_thread_req *)){
 			if(n < 0)
 				printk("io_thread - read failed, fd = %d, "
 				       "err = %d\n", kernel_fd, -n);
@@ -1426,9 +1464,10 @@ int io_thread(void *arg)
 			continue;
 		}
 		io_count++;
-		do_io(&req);
-		n = os_write_file(kernel_fd, &req, sizeof(req));
-		if(n != sizeof(req))
+		do_io(req);
+		n = os_write_file(kernel_fd, &req,
+				  sizeof(struct io_thread_req *));
+		if(n != sizeof(struct io_thread_req *))
 			printk("io_thread - write failed, fd = %d, err = %d\n",
 			       kernel_fd, -n);
 	}