[PATCH] uml: allow ubd devices to be shared in a cluster

This adds a 'c' option to the ubd switch which turns off host file locking so
that the device can be shared, as with a cluster.  There's also some
whitespace cleanup while I was in this file.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 43 insertions, 33 deletions

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index fa617e0719ab..0336575d2448 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -1,4 +1,4 @@
-/* 
+/*
  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
  * Licensed under the GPL
  */
@@ -71,7 +71,7 @@ struct io_thread_req {
         int error;
 };
 
-extern int open_ubd_file(char *file, struct openflags *openflags,
+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);
@@ -137,7 +137,7 @@ static int fake_major = MAJOR_NR;
 
 static struct gendisk *ubd_gendisk[MAX_DEV];
 static struct gendisk *fake_gendisk[MAX_DEV];
- 
+
 #ifdef CONFIG_BLK_DEV_UBD_SYNC
 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
                                          .cl = 1 })
@@ -168,6 +168,7 @@ struct ubd {
         __u64 size;
         struct openflags boot_openflags;
         struct openflags openflags;
+        int shared;
         int no_cow;
         struct cow cow;
         struct platform_device pdev;
@@ -189,6 +190,7 @@ struct ubd {
         .boot_openflags =       OPEN_FLAGS, \
         .openflags =            OPEN_FLAGS, \
         .no_cow =               0, \
+        .shared =               0, \
         .cow =                  DEFAULT_COW, \
 }
 
@@ -305,7 +307,7 @@ static int ubd_setup_common(char *str, int *index_out)
                 }
                 major = simple_strtoul(str, &end, 0);
                 if((*end != '\0') || (end == str)){
-                        printk(KERN_ERR 
+                        printk(KERN_ERR
                                "ubd_setup : didn't parse major number\n");
                         return(1);
                 }
@@ -316,7 +318,7 @@ static int ubd_setup_common(char *str, int *index_out)
                         printk(KERN_ERR "Can't assign a fake major twice\n");
                         goto out1;
                 }
- 
+
                 fake_major = major;
 
                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
@@ -351,7 +353,7 @@ static int ubd_setup_common(char *str, int *index_out)
         if (index_out)
                 *index_out = n;
 
-        for (i = 0; i < 4; i++) {
+        for (i = 0; i < sizeof("rscd="); i++) {
                 switch (*str) {
                 case 'r':
                         flags.w = 0;
@@ -362,11 +364,14 @@ static int ubd_setup_common(char *str, int *index_out)
                 case 'd':
                         dev->no_cow = 1;
                         break;
+                case 'c':
+                        dev->shared = 1;
+                        break;
                 case '=':
                         str++;
                         goto break_loop;
                 default:
-                        printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r,s or d)\n");
+                        printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r, s, c, or d)\n");
                         goto out;
                 }
                 str++;
@@ -515,7 +520,7 @@ static void ubd_handler(void)
                 spin_unlock(&ubd_io_lock);
                 return;
         }
-        
+
         ubd_finish(rq, req.error);
         reactivate_fd(thread_fd, UBD_IRQ);      
         do_ubd_request(ubd_queue);
@@ -532,7 +537,7 @@ static int io_pid = -1;
 
 void kill_io_thread(void)
 {
-        if(io_pid != -1) 
+        if(io_pid != -1)
                 os_kill_process(io_pid, 1);
 }
 
@@ -567,14 +572,15 @@ static int ubd_open_dev(struct ubd *dev)
         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, back_ptr,
-                                &dev->cow.bitmap_offset, &dev->cow.bitmap_len, 
-                                &dev->cow.data_offset, create_ptr);
+        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);
 
         if((dev->fd == -ENOENT) && create_cow){
-                dev->fd = create_cow_file(dev->file, dev->cow.file, 
+                dev->fd = create_cow_file(dev->file, dev->cow.file,
                                           dev->openflags, 1 << 9, PAGE_SIZE,
-                                          &dev->cow.bitmap_offset, 
+                                          &dev->cow.bitmap_offset,
                                           &dev->cow.bitmap_len,
                                           &dev->cow.data_offset);
                 if(dev->fd >= 0){
@@ -598,16 +604,16 @@ static int ubd_open_dev(struct ubd *dev)
                 }
                 flush_tlb_kernel_vm();
 
-                err = read_cow_bitmap(dev->fd, dev->cow.bitmap, 
-                                      dev->cow.bitmap_offset, 
+                err = read_cow_bitmap(dev->fd, dev->cow.bitmap,
+                                      dev->cow.bitmap_offset,
                                       dev->cow.bitmap_len);
                 if(err < 0)
                         goto error;
 
                 flags = dev->openflags;
                 flags.w = 0;
-                err = open_ubd_file(dev->cow.file, &flags, NULL, NULL, NULL, 
-                                    NULL, NULL);
+                err = open_ubd_file(dev->cow.file, &flags, dev->shared, NULL,
+                                    NULL, NULL, NULL, NULL);
                 if(err < 0) goto error;
                 dev->cow.fd = err;
         }
@@ -685,11 +691,11 @@ static int ubd_add(int n)
         dev->size = ROUND_BLOCK(dev->size);
 
         err = ubd_new_disk(MAJOR_NR, dev->size, n, &ubd_gendisk[n]);
-        if(err) 
+        if(err)
                 goto out_close;
- 
+
         if(fake_major != MAJOR_NR)
-                ubd_new_disk(fake_major, dev->size, n, 
+                ubd_new_disk(fake_major, dev->size, n,
                              &fake_gendisk[n]);
 
         /* perhaps this should also be under the "if (fake_major)" above */
@@ -854,7 +860,7 @@ int ubd_init(void)
                         return -1;
         }
         platform_driver_register(&ubd_driver);
-        for (i = 0; i < MAX_DEV; i++) 
+        for (i = 0; i < MAX_DEV; i++)
                 ubd_add(i);
         return 0;
 }
@@ -872,16 +878,16 @@ int ubd_driver_init(void){
                  * enough. So use anyway the io thread. */
         }
         stack = alloc_stack(0, 0);
-        io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *), 
+        io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
                                  &thread_fd);
         if(io_pid < 0){
-                printk(KERN_ERR 
+                printk(KERN_ERR
                        "ubd : Failed to start I/O thread (errno = %d) - "
                        "falling back to synchronous I/O\n", -io_pid);
                 io_pid = -1;
                 return(0);
         }
-        err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr, 
+        err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
                              SA_INTERRUPT, "ubd", ubd_dev);
         if(err != 0)
                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
@@ -978,7 +984,7 @@ static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
         if(req->op == UBD_READ) {
                 for(i = 0; i < req->length >> 9; i++){
                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
-                                ubd_set_bit(i, (unsigned char *) 
+                                ubd_set_bit(i, (unsigned char *)
                                             &req->sector_mask);
                 }
         }
@@ -999,7 +1005,7 @@ static int prepare_request(struct request *req, struct io_thread_req *io_req)
 
         /* This should be impossible now */
         if((rq_data_dir(req) == WRITE) && !dev->openflags.w){
-                printk("Write attempted on readonly ubd device %s\n", 
+                printk("Write attempted on readonly ubd device %s\n",
                        disk->disk_name);
                 end_request(req, 0);
                 return(1);
@@ -1182,7 +1188,7 @@ int read_cow_bitmap(int fd, void *buf, int offset, int len)
         return(0);
 }
 
-int open_ubd_file(char *file, struct openflags *openflags,
+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)
@@ -1206,10 +1212,14 @@ int open_ubd_file(char *file, struct openflags *openflags,
                         return fd;
         }
 
-        err = os_lock_file(fd, openflags->w);
-        if(err < 0){
-                printk("Failed to lock '%s', err = %d\n", file, -err);
-                goto out_close;
+        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! */
@@ -1260,7 +1270,7 @@ int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
         int err, fd;
 
         flags.c = 1;
-        fd = open_ubd_file(cow_file, &flags, NULL, NULL, NULL, NULL, NULL);
+        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,