uml: convert to seq_file/proc_fops
[safe/jmp/linux-2.6] / arch / um / drivers / ubd_kern.c
index 8f6bb93..5ff5546 100644 (file)
  * James McMechan
  */
 
-#define MAJOR_NR UBD_MAJOR
 #define UBD_SHIFT 4
 
-#include "linux/config.h"
+#include "linux/kernel.h"
 #include "linux/module.h"
 #include "linux/blkdev.h"
+#include "linux/ata.h"
 #include "linux/hdreg.h"
 #include "linux/init.h"
-#include "linux/devfs_fs_kernel.h"
 #include "linux/cdrom.h"
 #include "linux/proc_fs.h"
+#include "linux/seq_file.h"
 #include "linux/ctype.h"
 #include "linux/capability.h"
 #include "linux/mm.h"
 #include "linux/genhd.h"
 #include "linux/spinlock.h"
 #include "linux/platform_device.h"
+#include "linux/scatterlist.h"
 #include "asm/segment.h"
 #include "asm/uaccess.h"
 #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"
@@ -58,6 +58,7 @@
 enum ubd_req { UBD_READ, UBD_WRITE };
 
 struct io_thread_req {
+       struct request *req;
        enum ubd_req op;
        int fds[2];
        unsigned long offsets[2];
@@ -71,18 +72,6 @@ struct io_thread_req {
        int error;
 };
 
-extern int open_ubd_file(char *file, struct openflags *openflags, int shared,
-                        char **backing_file_out, int *bitmap_offset_out,
-                        unsigned long *bitmap_len_out, int *data_offset_out,
-                        int *create_cow_out);
-extern int create_cow_file(char *cow_file, char *backing_file,
-                          struct openflags flags, int sectorsize,
-                          int alignment, int *bitmap_offset_out,
-                          unsigned long *bitmap_len_out,
-                          int *data_offset_out);
-extern int read_cow_bitmap(int fd, void *buf, int offset, int len);
-extern void do_io(struct io_thread_req *req);
-
 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
 {
        __u64 n;
@@ -91,7 +80,7 @@ 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)
@@ -108,20 +97,17 @@ static inline void ubd_set_bit(__u64 bit, unsigned char *data)
 
 #define DRIVER_NAME "uml-blkdev"
 
-static DEFINE_SPINLOCK(ubd_io_lock);
-static DEFINE_SPINLOCK(ubd_lock);
+static DEFINE_MUTEX(ubd_lock);
 
-static void (*do_ubd)(void);
-
-static int ubd_open(struct inode * inode, struct file * filp);
-static int ubd_release(struct inode * inode, struct file * file);
-static int ubd_ioctl(struct inode * inode, struct file * file,
+static int ubd_open(struct block_device *bdev, fmode_t mode);
+static int ubd_release(struct gendisk *disk, fmode_t mode);
+static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
                     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 = {
+static const struct block_device_operations ubd_blops = {
         .owner         = THIS_MODULE,
         .open          = ubd_open,
         .release       = ubd_release,
@@ -129,12 +115,8 @@ static struct block_device_operations ubd_blops = {
        .getgeo         = ubd_getgeo,
 };
 
-/* Protected by the queue_lock */
-static request_queue_t *ubd_queue;
-
 /* Protected by ubd_lock */
-static int fake_major = MAJOR_NR;
-
+static int fake_major = UBD_MAJOR;
 static struct gendisk *ubd_gendisk[MAX_DEV];
 static struct gendisk *fake_gendisk[MAX_DEV];
 
@@ -145,41 +127,48 @@ static struct gendisk *fake_gendisk[MAX_DEV];
 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
                                         .cl = 1 })
 #endif
-
-/* Not protected - changed only in ubd_setup_common and then only to
- * to enable O_SYNC.
- */
 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;
        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;
        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;
+       struct request_queue *queue;
+       spinlock_t lock;
+       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 { \
@@ -189,23 +178,17 @@ struct ubd {
        .size =                 -1, \
        .boot_openflags =       OPEN_FLAGS, \
        .openflags =            OPEN_FLAGS, \
-        .no_cow =               0, \
+       .no_cow =               0, \
        .shared =               0, \
-        .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);
+       .cow =                  DEFAULT_COW, \
+       .lock =                 SPIN_LOCK_UNLOCKED,     \
+       .request =              NULL, \
+       .start_sg =             0, \
+       .end_sg =               0, \
 }
 
-__initcall(ubd0_init);
+/* Protected by ubd_lock */
+static 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;
@@ -218,24 +201,26 @@ static void make_proc_ide(void)
        proc_ide = proc_mkdir("ide0", proc_ide_root);
 }
 
-static int proc_ide_read_media(char *page, char **start, off_t off, int count,
-                              int *eof, void *data)
+static int fake_ide_media_proc_show(struct seq_file *m, void *v)
 {
-       int len;
-
-       strcpy(page, "disk\n");
-       len = strlen("disk\n");
-       len -= off;
-       if (len < count){
-               *eof = 1;
-               if (len <= 0) return 0;
-       }
-       else len = count;
-       *start = page + off;
-       return len;
+       seq_puts(m, "disk\n");
+       return 0;
 }
 
-static void make_ide_entries(char *dev_name)
+static int fake_ide_media_proc_open(struct inode *inode, struct file *file)
+{
+       return single_open(file, fake_ide_media_proc_show, NULL);
+}
+
+static const struct file_operations fake_ide_media_proc_fops = {
+       .owner          = THIS_MODULE,
+       .open           = fake_ide_media_proc_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
+
+static void make_ide_entries(const char *dev_name)
 {
        struct proc_dir_entry *dir, *ent;
        char name[64];
@@ -245,20 +230,16 @@ static void make_ide_entries(char *dev_name)
        dir = proc_mkdir(dev_name, proc_ide);
        if(!dir) return;
 
-       ent = create_proc_entry("media", S_IFREG|S_IRUGO, dir);
+       ent = proc_create("media", S_IRUGO, dir, &fake_ide_media_proc_fops);
        if(!ent) return;
-       ent->nlink = 1;
-       ent->data = NULL;
-       ent->read_proc = proc_ide_read_media;
-       ent->write_proc = NULL;
-       sprintf(name,"ide0/%s", dev_name);
+       snprintf(name, sizeof(name), "ide0/%s", dev_name);
        proc_symlink(dev_name, proc_ide_root, name);
 }
 
 static int fake_ide_setup(char *str)
 {
        fake_ide = 1;
-       return(1);
+       return 1;
 }
 
 __setup("fake_ide", fake_ide_setup);
@@ -276,23 +257,27 @@ 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 <= 'h')) {
+       else if (('a' <= *str) && (*str <= 'z')) {
                n = *str - 'a';
                str++;
                *ptr = str;
        }
-       return(n);
+       return n;
 }
 
-static int ubd_setup_common(char *str, int *index_out)
+/* 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, char **error_out)
 {
-       struct ubd *dev;
+       struct ubd *ubd_dev;
        struct openflags flags = global_openflags;
        char *backing_file;
-       int n, err, i;
+       int n, err = 0, i;
 
        if(index_out) *index_out = -1;
        n = *str;
@@ -303,56 +288,55 @@ static int ubd_setup_common(char *str, int *index_out)
                str++;
                if(!strcmp(str, "sync")){
                        global_openflags = of_sync(global_openflags);
-                       return(0);
+                       goto out1;
                }
+
+               err = -EINVAL;
                major = simple_strtoul(str, &end, 0);
                if((*end != '\0') || (end == str)){
-                       printk(KERN_ERR
-                              "ubd_setup : didn't parse major number\n");
-                       return(1);
+                       *error_out = "Didn't parse major number";
+                       goto out1;
                }
 
-               err = 1;
-               spin_lock(&ubd_lock);
-               if(fake_major != MAJOR_NR){
-                       printk(KERN_ERR "Can't assign a fake major twice\n");
-                       goto out1;
-               }
+               mutex_lock(&ubd_lock);
+               if (fake_major != UBD_MAJOR) {
+                       *error_out = "Can't assign a fake major twice";
+                       goto out1;
+               }
 
-               fake_major = major;
+               fake_major = major;
 
                printk(KERN_INFO "Setting extra ubd major number to %d\n",
                       major);
-               err = 0;
-       out1:
-               spin_unlock(&ubd_lock);
-               return(err);
+               err = 0;
+       out1:
+               mutex_unlock(&ubd_lock);
+               return err;
        }
 
        n = parse_unit(&str);
        if(n < 0){
-               printk(KERN_ERR "ubd_setup : couldn't parse unit number "
-                      "'%s'\n", str);
-               return(1);
+               *error_out = "Couldn't parse device number";
+               return -EINVAL;
        }
        if(n >= MAX_DEV){
-               printk(KERN_ERR "ubd_setup : index %d out of range "
-                      "(%d devices, from 0 to %d)\n", n, MAX_DEV, MAX_DEV - 1);
-               return(1);
+               *error_out = "Device number out of range";
+               return 1;
        }
 
-       err = 1;
-       spin_lock(&ubd_lock);
+       err = -EBUSY;
+       mutex_lock(&ubd_lock);
 
-       dev = &ubd_dev[n];
-       if(dev->file != NULL){
-               printk(KERN_ERR "ubd_setup : device already configured\n");
+       ubd_dev = &ubd_devs[n];
+       if(ubd_dev->file != NULL){
+               *error_out = "Device is already configured";
                goto out;
        }
 
        if (index_out)
                *index_out = n;
 
+       err = -EINVAL;
        for (i = 0; i < sizeof("rscd="); i++) {
                switch (*str) {
                case 'r':
@@ -362,56 +346,63 @@ 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++;
                        goto break_loop;
                default:
-                       printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r, s, c, or d)\n");
+                       *error_out = "Expected '=' or flag letter "
+                               "(r, s, c, or d)";
                        goto out;
                }
                str++;
        }
 
-        if (*str == '=')
-               printk(KERN_ERR "ubd_setup : Too many flags specified\n");
-        else
-               printk(KERN_ERR "ubd_setup : Expected '='\n");
+       if (*str == '=')
+               *error_out = "Too many flags specified";
+       else
+               *error_out = "Missing '='";
        goto out;
 
 break_loop:
-       err = 0;
        backing_file = strchr(str, ',');
 
-       if (!backing_file) {
+       if (backing_file == NULL)
                backing_file = strchr(str, ':');
-       }
 
-       if(backing_file){
-               if(dev->no_cow)
-                       printk(KERN_ERR "Can't specify both 'd' and a "
-                              "cow file\n");
+       if(backing_file != NULL){
+               if(ubd_dev->no_cow){
+                       *error_out = "Can't specify both 'd' and a cow file";
+                       goto out;
+               }
                else {
                        *backing_file = '\0';
                        backing_file++;
                }
        }
-       dev->file = str;
-       dev->cow.file = backing_file;
-       dev->boot_openflags = flags;
+       err = 0;
+       ubd_dev->file = str;
+       ubd_dev->cow.file = backing_file;
+       ubd_dev->boot_openflags = flags;
 out:
-       spin_unlock(&ubd_lock);
-       return(err);
+       mutex_unlock(&ubd_lock);
+       return err;
 }
 
 static int ubd_setup(char *str)
 {
-       ubd_setup_common(str, NULL);
-       return(1);
+       char *error;
+       int err;
+
+       err = ubd_setup_common(str, NULL, &error);
+       if(err)
+               printk(KERN_ERR "Failed to initialize device with \"%s\" : "
+                      "%s\n", str, error);
+       return 1;
 }
 
 __setup("ubd", ubd_setup);
@@ -423,7 +414,7 @@ __uml_help(ubd_setup,
 "    use either a ':' or a ',': the first one allows writing things like;\n"
 "      ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
 "    while with a ',' the shell would not expand the 2nd '~'.\n"
-"    When using only one filename, UML will detect whether to thread it like\n"
+"    When using only one filename, UML will detect whether to treat it like\n"
 "    a COW file or a backing file. To override this detection, add the 'd'\n"
 "    flag:\n"
 "      ubd0d=BackingFile\n"
@@ -434,14 +425,17 @@ __uml_help(ubd_setup,
 "    machine by running 'dd' on the device. <n> must be in the range\n"
 "    0 to 7. Appending an 'r' to the number will cause that device\n"
 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
-"    an 's' will cause data to be written to disk on the host immediately.\n\n"
+"    an 's' will cause data to be written to disk on the host immediately.\n"
+"    'c' will cause the device to be treated as being shared between multiple\n"
+"    UMLs and file locking will be turned off - this is appropriate for a\n"
+"    cluster filesystem and inappropriate at almost all other times.\n\n"
 );
 
 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);
@@ -453,217 +447,373 @@ __uml_help(udb_setup,
 "    in the boot output.\n\n"
 );
 
-static int fakehd_set = 0;
-static int fakehd(char *str)
+static void do_ubd_request(struct request_queue * q);
+
+/* Only changed by ubd_init, which is an initcall. */
+static int thread_fd = -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)
 {
-       printk(KERN_INFO "fakehd : Changing ubd name to \"hd\".\n");
-       fakehd_set = 1;
-       return 1;
-}
+       struct io_thread_req *req;
+       struct ubd *ubd;
+       struct list_head *list, *next_ele;
+       unsigned long flags;
+       int n;
 
-__setup("fakehd", fakehd);
-__uml_help(fakehd,
-"fakehd\n"
-"    Change the ubd device name to \"hd\".\n\n"
-);
+       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;
+               }
 
-static void do_ubd_request(request_queue_t * q);
+               blk_end_request(req->req, 0, req->length);
+               kfree(req);
+       }
+       reactivate_fd(thread_fd, UBD_IRQ);
+
+       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;
+}
 
 /* Only changed by ubd_init, which is an initcall. */
-int thread_fd = -1;
+static int io_pid = -1;
 
-/* Changed by ubd_handler, which is serialized because interrupts only
- * happen on CPU 0.
- */
-int intr_count = 0;
+static void kill_io_thread(void)
+{
+       if(io_pid != -1)
+               os_kill_process(io_pid, 1);
+}
+
+__uml_exitcall(kill_io_thread);
 
-/* call ubd_finish if you need to serialize */
-static void __ubd_finish(struct request *req, int error)
+static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
 {
-       int nsect;
+       char *file;
 
-       if(error){
-               end_request(req, 0);
-               return;
-       }
-       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);
+       file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
+       return os_file_size(file, size_out);
 }
 
-static inline void ubd_finish(struct request *req, int error)
+static int read_cow_bitmap(int fd, void *buf, int offset, int len)
 {
-       spin_lock(&ubd_io_lock);
-       __ubd_finish(req, error);
-       spin_unlock(&ubd_io_lock);
+       int err;
+
+       err = os_seek_file(fd, offset);
+       if (err < 0)
+               return err;
+
+       err = os_read_file(fd, buf, len);
+       if (err < 0)
+               return err;
+
+       return 0;
 }
 
-/* Called without ubd_io_lock held */
-static void ubd_handler(void)
+static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
 {
-       struct io_thread_req req;
-       struct request *rq = elv_next_request(ubd_queue);
-       int n;
+       unsigned long modtime;
+       unsigned long long actual;
+       int err;
 
-       do_ubd = NULL;
-       intr_count++;
-       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);
-               spin_lock(&ubd_io_lock);
-               end_request(rq, 0);
-               spin_unlock(&ubd_io_lock);
-               return;
+       err = os_file_modtime(file, &modtime);
+       if (err < 0) {
+               printk(KERN_ERR "Failed to get modification time of backing "
+                      "file \"%s\", err = %d\n", file, -err);
+               return err;
+       }
+
+       err = os_file_size(file, &actual);
+       if (err < 0) {
+               printk(KERN_ERR "Failed to get size of backing file \"%s\", "
+                      "err = %d\n", file, -err);
+               return err;
        }
 
-       ubd_finish(rq, req.error);
-       reactivate_fd(thread_fd, UBD_IRQ);      
-       do_ubd_request(ubd_queue);
+       if (actual != size) {
+               /*__u64 can be a long on AMD64 and with %lu GCC complains; so
+                * the typecast.*/
+               printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
+                      "vs backing file\n", (unsigned long long) size, actual);
+               return -EINVAL;
+       }
+       if (modtime != mtime) {
+               printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "
+                      "backing file\n", mtime, modtime);
+               return -EINVAL;
+       }
+       return 0;
 }
 
-static irqreturn_t ubd_intr(int irq, void *dev, struct pt_regs *unused)
+static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
 {
-       ubd_handler();
-       return(IRQ_HANDLED);
-}
+       struct uml_stat buf1, buf2;
+       int err;
 
-/* Only changed by ubd_init, which is an initcall. */
-static int io_pid = -1;
+       if (from_cmdline == NULL)
+               return 0;
+       if (!strcmp(from_cmdline, from_cow))
+               return 0;
 
-void kill_io_thread(void)
-{
-       if(io_pid != -1)
-               os_kill_process(io_pid, 1);
+       err = os_stat_file(from_cmdline, &buf1);
+       if (err < 0) {
+               printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
+                      -err);
+               return 0;
+       }
+       err = os_stat_file(from_cow, &buf2);
+       if (err < 0) {
+               printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
+                      -err);
+               return 1;
+       }
+       if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
+               return 0;
+
+       printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
+              "\"%s\" specified in COW header of \"%s\"\n",
+              from_cmdline, from_cow, cow);
+       return 1;
 }
 
-__uml_exitcall(kill_io_thread);
+static int open_ubd_file(char *file, struct openflags *openflags, int shared,
+                 char **backing_file_out, int *bitmap_offset_out,
+                 unsigned long *bitmap_len_out, int *data_offset_out,
+                 int *create_cow_out)
+{
+       time_t mtime;
+       unsigned long long size;
+       __u32 version, align;
+       char *backing_file;
+       int fd, err, sectorsize, asked_switch, mode = 0644;
+
+       fd = os_open_file(file, *openflags, mode);
+       if (fd < 0) {
+               if ((fd == -ENOENT) && (create_cow_out != NULL))
+                       *create_cow_out = 1;
+               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(KERN_INFO "Not locking \"%s\" on the host\n", file);
+       else {
+               err = os_lock_file(fd, openflags->w);
+               if (err < 0) {
+                       printk(KERN_ERR "Failed to lock '%s', err = %d\n",
+                              file, -err);
+                       goto out_close;
+               }
+       }
+
+       /* Successful return case! */
+       if (backing_file_out == NULL)
+               return fd;
+
+       err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
+                             &size, &sectorsize, &align, bitmap_offset_out);
+       if (err && (*backing_file_out != NULL)) {
+               printk(KERN_ERR "Failed to read COW header from COW file "
+                      "\"%s\", errno = %d\n", file, -err);
+               goto out_close;
+       }
+       if (err)
+               return fd;
 
-static int ubd_file_size(struct ubd *dev, __u64 *size_out)
+       asked_switch = path_requires_switch(*backing_file_out, backing_file,
+                                           file);
+
+       /* Allow switching only if no mismatch. */
+       if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
+                                                  mtime)) {
+               printk(KERN_ERR "Switching backing file to '%s'\n",
+                      *backing_file_out);
+               err = write_cow_header(file, fd, *backing_file_out,
+                                      sectorsize, align, &size);
+               if (err) {
+                       printk(KERN_ERR "Switch failed, errno = %d\n", -err);
+                       goto out_close;
+               }
+       } else {
+               *backing_file_out = backing_file;
+               err = backing_file_mismatch(*backing_file_out, size, mtime);
+               if (err)
+                       goto out_close;
+       }
+
+       cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
+                 bitmap_len_out, data_offset_out);
+
+       return fd;
+ out_close:
+       os_close_file(fd);
+       return err;
+}
+
+static int create_cow_file(char *cow_file, char *backing_file,
+                   struct openflags flags,
+                   int sectorsize, int alignment, int *bitmap_offset_out,
+                   unsigned long *bitmap_len_out, int *data_offset_out)
 {
-       char *file;
+       int err, fd;
 
-       file = dev->cow.file ? dev->cow.file : dev->file;
-       return(os_file_size(file, size_out));
+       flags.c = 1;
+       fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
+       if (fd < 0) {
+               err = fd;
+               printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
+                      cow_file, -err);
+               goto out;
+       }
+
+       err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
+                           bitmap_offset_out, bitmap_len_out,
+                           data_offset_out);
+       if (!err)
+               return fd;
+       os_close_file(fd);
+ out:
+       return err;
 }
 
-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(ubd_dev->cow.file != NULL){
+               blk_queue_max_sectors(ubd_dev->queue, 8 * sizeof(long));
 
-       if(dev->cow.file != NULL){
                err = -ENOMEM;
-               dev->cow.bitmap = (void *) vmalloc(dev->cow.bitmap_len);
-               if(dev->cow.bitmap == NULL){
+               ubd_dev->cow.bitmap = 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);
+       return 0;
  error:
-       os_close_file(dev->fd);
-       return(err);
+       os_close_file(ubd_dev->fd);
+       return err;
+}
+
+static void ubd_device_release(struct device *dev)
+{
+       struct ubd *ubd_dev = dev_get_drvdata(dev);
+
+       blk_cleanup_queue(ubd_dev->queue);
+       *ubd_dev = ((struct ubd) DEFAULT_UBD);
 }
 
-static int ubd_new_disk(int major, u64 size, int unit,
-                       struct gendisk **disk_out)
-                       
+static int ubd_disk_register(int major, u64 size, int unit,
+                            struct gendisk **disk_out)
 {
        struct gendisk *disk;
-       char from[sizeof("ubd/nnnnn\0")], to[sizeof("discnnnnn/disc\0")];
-       int err;
 
        disk = alloc_disk(1 << UBD_SHIFT);
        if(disk == NULL)
-               return(-ENOMEM);
+               return -ENOMEM;
 
        disk->major = major;
        disk->first_minor = unit << UBD_SHIFT;
        disk->fops = &ubd_blops;
        set_capacity(disk, size / 512);
-       if(major == MAJOR_NR){
+       if (major == UBD_MAJOR)
                sprintf(disk->disk_name, "ubd%c", 'a' + unit);
-               sprintf(disk->devfs_name, "ubd/disc%d", unit);
-               sprintf(from, "ubd/%d", unit);
-               sprintf(to, "disc%d/disc", unit);
-               err = devfs_mk_symlink(from, to);
-               if(err)
-                       printk("ubd_new_disk failed to make link from %s to "
-                              "%s, error = %d\n", from, to, err);
-       }
-       else {
+       else
                sprintf(disk->disk_name, "ubd_fake%d", unit);
-               sprintf(disk->devfs_name, "ubd_fake/disc%d", 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;
+       if (major == UBD_MAJOR) {
+               ubd_devs[unit].pdev.id   = unit;
+               ubd_devs[unit].pdev.name = DRIVER_NAME;
+               ubd_devs[unit].pdev.dev.release = ubd_device_release;
+               dev_set_drvdata(&ubd_devs[unit].pdev.dev, &ubd_devs[unit]);
+               platform_device_register(&ubd_devs[unit].pdev);
+               disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
        }
 
-       disk->private_data = &ubd_dev[unit];
-       disk->queue = ubd_queue;
+       disk->private_data = &ubd_devs[unit];
+       disk->queue = ubd_devs[unit].queue;
        add_disk(disk);
 
        *disk_out = disk;
@@ -672,134 +822,162 @@ static int ubd_new_disk(int major, u64 size, int unit,
 
 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
 
-static int ubd_add(int n)
+static int ubd_add(int n, char **error_out)
 {
-       struct ubd *dev = &ubd_dev[n];
-       int err;
+       struct ubd *ubd_dev = &ubd_devs[n];
+       int err = 0;
 
-       err = -ENODEV;
-       if(dev->file == NULL)
+       if(ubd_dev->file == NULL)
                goto out;
 
-       if (ubd_open_dev(dev))
+       err = ubd_file_size(ubd_dev, &ubd_dev->size);
+       if(err < 0){
+               *error_out = "Couldn't determine size of device's file";
                goto out;
+       }
 
-       err = ubd_file_size(dev, &dev->size);
-       if(err < 0)
-               goto out_close;
+       ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
 
-       dev->size = ROUND_BLOCK(dev->size);
+       INIT_LIST_HEAD(&ubd_dev->restart);
+       sg_init_table(ubd_dev->sg, MAX_SG);
 
-       err = ubd_new_disk(MAJOR_NR, dev->size, n, &ubd_gendisk[n]);
-       if(err)
-               goto out_close;
+       err = -ENOMEM;
+       ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
+       if (ubd_dev->queue == NULL) {
+               *error_out = "Failed to initialize device queue";
+               goto out;
+       }
+       ubd_dev->queue->queuedata = ubd_dev;
 
-       if(fake_major != MAJOR_NR)
-               ubd_new_disk(fake_major, dev->size, n,
-                            &fake_gendisk[n]);
+       blk_queue_max_hw_segments(ubd_dev->queue, MAX_SG);
+       err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);
+       if(err){
+               *error_out = "Failed to register device";
+               goto out_cleanup;
+       }
 
-       /* perhaps this should also be under the "if (fake_major)" above */
-       /* using the fake_disk->disk_name and also the fakehd_set name */
+       if (fake_major != UBD_MAJOR)
+               ubd_disk_register(fake_major, ubd_dev->size, n,
+                                 &fake_gendisk[n]);
+
+       /*
+        * Perhaps this should also be under the "if (fake_major)" above
+        * using the fake_disk->disk_name
+        */
        if (fake_ide)
                make_ide_entries(ubd_gendisk[n]->disk_name);
 
        err = 0;
-out_close:
-       ubd_close(dev);
 out:
        return err;
+
+out_cleanup:
+       blk_cleanup_queue(ubd_dev->queue);
+       goto out;
 }
 
-static int ubd_config(char *str)
+static int ubd_config(char *str, char **error_out)
 {
-       int n, err;
+       int n, ret;
 
+       /* This string is possibly broken up and stored, so it's only
+        * freed if ubd_setup_common fails, or if only general options
+        * were set.
+        */
        str = kstrdup(str, GFP_KERNEL);
-       if(str == NULL){
-               printk(KERN_ERR "ubd_config failed to strdup string\n");
-               return(1);
+       if (str == NULL) {
+               *error_out = "Failed to allocate memory";
+               return -ENOMEM;
        }
-       err = ubd_setup_common(str, &n);
-       if(err){
-               kfree(str);
-               return(-1);
+
+       ret = ubd_setup_common(str, &n, error_out);
+       if (ret)
+               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, error_out);
+       if (ret)
+               ubd_devs[n].file = NULL;
+       mutex_unlock(&ubd_lock);
+
+out:
+       return ret;
 
-       return(err);
+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);
        if((n >= MAX_DEV) || (n < 0)){
                *error_out = "ubd_get_config : device number out of range";
-               return(-1);
+               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);
-       return(len);
+       mutex_unlock(&ubd_lock);
+       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)
+static int ubd_remove(int n, char **error_out)
 {
-       struct ubd *dev;
+       struct gendisk *disk = ubd_gendisk[n];
+       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]);
-       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]);
@@ -807,23 +985,26 @@ static int ubd_remove(int n)
                fake_gendisk[n] = NULL;
        }
 
-       platform_device_unregister(&dev->pdev);
-       *dev = ((struct ubd) DEFAULT_UBD);
        err = 0;
+       platform_device_unregister(&ubd_dev->pdev);
 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.  The structure itself is const except for .list.
+ */
 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,
 };
 
-static int ubd_mc_init(void)
+static int __init ubd_mc_init(void)
 {
        mconsole_register_dev(&ubd_mc);
        return 0;
@@ -831,26 +1012,36 @@ static int ubd_mc_init(void)
 
 __initcall(ubd_mc_init);
 
+static int __init ubd0_init(void)
+{
+       struct ubd *ubd_dev = &ubd_devs[0];
+
+       mutex_lock(&ubd_lock);
+       if(ubd_dev->file == NULL)
+               ubd_dev->file = "root_fs";
+       mutex_unlock(&ubd_lock);
+
+       return 0;
+}
+
+__initcall(ubd0_init);
+
+/* Used in ubd_init, which is an initcall */
 static struct platform_driver ubd_driver = {
        .driver = {
                .name  = DRIVER_NAME,
        },
 };
 
-int ubd_init(void)
+static int __init ubd_init(void)
 {
-        int i;
+       char *error;
+       int i, err;
 
-       if (register_blkdev(MAJOR_NR, "ubd"))
+       if (register_blkdev(UBD_MAJOR, "ubd"))
                return -1;
 
-       ubd_queue = blk_init_queue(do_ubd_request, &ubd_io_lock);
-       if (!ubd_queue) {
-               unregister_blkdev(MAJOR_NR, "ubd");
-               return -1;
-       }
-               
-       if (fake_major != MAJOR_NR) {
+       if (fake_major != UBD_MAJOR) {
                char name[sizeof("ubd_nnn\0")];
 
                snprintf(name, sizeof(name), "ubd_%d", fake_major);
@@ -858,14 +1049,20 @@ int ubd_init(void)
                        return -1;
        }
        platform_driver_register(&ubd_driver);
-       for (i = 0; i < MAX_DEV; i++)
-               ubd_add(i);
+       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);
        return 0;
 }
 
 late_initcall(ubd_init);
 
-int ubd_driver_init(void){
+static int __init ubd_driver_init(void){
        unsigned long stack;
        int err;
 
@@ -883,10 +1080,10 @@ int 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,
-                            SA_INTERRUPT, "ubd", ubd_dev);
+                            IRQF_DISABLED, "ubd", ubd_devs);
        if(err != 0)
                printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
        return 0;
@@ -894,41 +1091,40 @@ int ubd_driver_init(void){
 
 device_initcall(ubd_driver_init);
 
-static int ubd_open(struct inode *inode, struct file *filp)
+static int ubd_open(struct block_device *bdev, fmode_t mode)
 {
-       struct gendisk *disk = inode->i_bdev->bd_disk;
-       struct ubd *dev = disk->private_data;
+       struct gendisk *disk = bdev->bd_disk;
+       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((mode & FMODE_WRITE) && !ubd_dev->openflags.w){
+               if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
                err = -EROFS;
        }*/
  out:
-       return(err);
+       return err;
 }
 
-static int ubd_release(struct inode * inode, struct file * file)
+static int ubd_release(struct gendisk *disk, fmode_t mode)
 {
-       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);
-       return(0);
+       if(--ubd_dev->count == 0)
+               ubd_close_dev(ubd_dev);
+       return 0;
 }
 
 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
@@ -959,8 +1155,8 @@ static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
         * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
         * for the original diagnosis.
         */
-       if(*cow_offset == ((bitmap_len + sizeof(unsigned long) - 1) /
-                          sizeof(unsigned long) - 1))
+       if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
+                                        sizeof(unsigned long)) - 1))
                (*cow_offset)--;
 
        bitmap_words[0] = bitmap[*cow_offset];
@@ -984,36 +1180,25 @@ 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,
                           req->bitmap_words, bitmap_len);
 }
 
-/* Called with ubd_io_lock held */
-static int prepare_request(struct request *req, struct io_thread_req *io_req)
+/* Called with dev->lock held */
+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 *dev = disk->private_data;
-       __u64 offset;
-       int len;
-
-       if(req->rq_status == RQ_INACTIVE) return(1);
-
-       /* This should be impossible now */
-       if((rq_data_dir(req) == WRITE) && !dev->openflags.w){
-               printk("Write attempted on readonly ubd device %s\n",
-                      disk->disk_name);
-               end_request(req, 0);
-               return(1);
-       }
+       struct ubd *ubd_dev = disk->private_data;
 
-       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->req = req;
+       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;
@@ -1022,268 +1207,112 @@ 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->buffer = req->buffer;
+       io_req->offsets[1] = ubd_dev->cow.data_offset;
+       io_req->buffer = page_address(page) + page_offset;
        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);
 }
 
-/* Called with ubd_io_lock held */
-static void do_ubd_request(request_queue_t *q)
+/* Called with dev->lock held */
+static void do_ubd_request(struct request_queue *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);
-                       }
+       sector_t sector;
+       int n;
+
+       while(1){
+               struct ubd *dev = q->queuedata;
+               if(dev->end_sg == 0){
+                       struct request *req = blk_fetch_request(q);
+                       if(req == NULL)
+                               return;
+
+                       dev->request = req;
+                       dev->start_sg = 0;
+                       dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
                }
-       }
-       else {
-               if(do_ubd || (req = elv_next_request(q)) == NULL)
-                       return;
-               err = prepare_request(req, &io_req);
-               if(!err){
-                       do_ubd = ubd_handler;
-                       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);
+
+               req = dev->request;
+               sector = blk_rq_pos(req);
+               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)sector << 9,
+                                       sg->offset, sg->length, sg_page(sg));
+
+                       sector += sg->length >> 9;
+                       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);
+                               kfree(io_req);
+                               return;
+                       }
+
+                       dev->start_sg++;
                }
+               dev->end_sg = 0;
+               dev->request = NULL;
        }
 }
 
 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,
+static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
                     unsigned int cmd, unsigned long arg)
 {
-       struct ubd *dev = inode->i_bdev->bd_disk->private_data;
-       struct hd_driveid ubd_id = {
-               .cyls           = 0,
-               .heads          = 128,
-               .sectors        = 32,
-       };
+       struct ubd *ubd_dev = bdev->bd_disk->private_data;
+       u16 ubd_id[ATA_ID_WORDS];
 
        switch (cmd) {
                struct cdrom_volctrl volume;
        case HDIO_GET_IDENTITY:
-               ubd_id.cyls = dev->size / (128 * 32 * 512);
+               memset(&ubd_id, 0, ATA_ID_WORDS * 2);
+               ubd_id[ATA_ID_CYLS]     = ubd_dev->size / (128 * 32 * 512);
+               ubd_id[ATA_ID_HEADS]    = 128;
+               ubd_id[ATA_ID_SECTORS]  = 32;
                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(-EINVAL);
-}
-
-static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
-{
-       struct uml_stat buf1, buf2;
-       int err;
-
-       if(from_cmdline == NULL)
-               return 0;
-       if(!strcmp(from_cmdline, from_cow))
-               return 0;
-
-       err = os_stat_file(from_cmdline, &buf1);
-       if(err < 0){
-               printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
+                       return -EFAULT;
                return 0;
        }
-       err = os_stat_file(from_cow, &buf2);
-       if(err < 0){
-               printk("Couldn't stat '%s', err = %d\n", from_cow, -err);
-               return 1;
-       }
-       if((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
-               return 0;
-
-       printk("Backing file mismatch - \"%s\" requested,\n"
-              "\"%s\" specified in COW header of \"%s\"\n",
-              from_cmdline, from_cow, cow);
-       return 1;
-}
-
-static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
-{
-       unsigned long modtime;
-       unsigned long long actual;
-       int err;
-
-       err = os_file_modtime(file, &modtime);
-       if(err < 0){
-               printk("Failed to get modification time of backing file "
-                      "\"%s\", err = %d\n", file, -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);
-       }
-
-       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);
-       }
-       if(modtime != mtime){
-               printk("mtime mismatch (%ld vs %ld) of COW header vs backing "
-                      "file\n", mtime, modtime);
-               return(-EINVAL);
-       }
-       return(0);
-}
-
-int read_cow_bitmap(int fd, void *buf, int offset, int len)
-{
-       int err;
-
-       err = os_seek_file(fd, offset);
-       if(err < 0)
-               return(err);
-
-       err = os_read_file(fd, buf, len);
-       if(err < 0)
-               return(err);
-
-       return(0);
-}
-
-int open_ubd_file(char *file, struct openflags *openflags, int shared,
-                 char **backing_file_out, int *bitmap_offset_out,
-                 unsigned long *bitmap_len_out, int *data_offset_out,
-                 int *create_cow_out)
-{
-       time_t mtime;
-       unsigned long long size;
-       __u32 version, align;
-       char *backing_file;
-       int fd, err, sectorsize, asked_switch, mode = 0644;
-
-       fd = os_open_file(file, *openflags, mode);
-       if (fd < 0) {
-               if ((fd == -ENOENT) && (create_cow_out != NULL))
-                       *create_cow_out = 1;
-                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);
-       else {
-               err = os_lock_file(fd, openflags->w);
-               if(err < 0){
-                       printk("Failed to lock '%s', err = %d\n", file, -err);
-                       goto out_close;
-               }
-       }
-
-       /* Succesful return case! */
-       if(backing_file_out == NULL)
-               return(fd);
-
-       err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
-                             &size, &sectorsize, &align, bitmap_offset_out);
-       if(err && (*backing_file_out != NULL)){
-               printk("Failed to read COW header from COW file \"%s\", "
-                      "errno = %d\n", file, -err);
-               goto out_close;
-       }
-       if(err)
-               return(fd);
-
-       asked_switch = path_requires_switch(*backing_file_out, backing_file, file);
-
-       /* Allow switching only if no mismatch. */
-       if (asked_switch && !backing_file_mismatch(*backing_file_out, size, mtime)) {
-               printk("Switching backing file to '%s'\n", *backing_file_out);
-               err = write_cow_header(file, fd, *backing_file_out,
-                                      sectorsize, align, &size);
-               if (err) {
-                       printk("Switch failed, errno = %d\n", -err);
-                       goto out_close;
-               }
-       } else {
-               *backing_file_out = backing_file;
-               err = backing_file_mismatch(*backing_file_out, size, mtime);
-               if (err)
-                       goto out_close;
-       }
-
-       cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
-                 bitmap_len_out, data_offset_out);
-
-        return fd;
- out_close:
-       os_close_file(fd);
-       return err;
-}
-
-int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
-                   int sectorsize, int alignment, int *bitmap_offset_out,
-                   unsigned long *bitmap_len_out, int *data_offset_out)
-{
-       int err, fd;
-
-       flags.c = 1;
-       fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
-       if(fd < 0){
-               err = fd;
-               printk("Open of COW file '%s' failed, errno = %d\n", cow_file,
-                      -err);
-               goto out;
-       }
-
-       err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
-                           bitmap_offset_out, bitmap_len_out,
-                           data_offset_out);
-       if(!err)
-               return(fd);
-       os_close_file(fd);
- out:
-       return(err);
+       return -EINVAL;
 }
 
 static int update_bitmap(struct io_thread_req *req)
@@ -1291,26 +1320,26 @@ 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)
+static void do_io(struct io_thread_req *req)
 {
        char *buf;
        unsigned long len;
@@ -1374,18 +1403,19 @@ 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)
 {
-       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);
@@ -1396,9 +1426,10 @@ 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);
        }