1 files changed, 195 insertions, 156 deletions

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 8bd9204ac1ab..70509ddaac03 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);
         }