added dummy disk

[tridge/junkcode.git] / trd / dummy_disk.c

diff --git a/trd/dummy_disk.c b/trd/dummy_disk.c
new file mode 100644 (file)
index 0000000..c2df1ec
--- /dev/null
+++ b/trd/dummy_disk.c
@@ -0,0 +1,120 @@
+/*
+  A dummy disk device. reads and write always succeed, but don't 
+  actually do anything
+
+  tridge@valinux.com, 2001
+*/
+
+#define MAJOR_NR   241
+
+#define DEVICE_NAME "ddisk"
+#define DEVICE_NR(device) (MINOR(device))
+
+#include <linux/major.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/blk.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <asm/setup.h>
+#include <asm/uaccess.h>
+
+#define DUMMY_BLOCK_SIZE 1024
+
+static int dummy_blocksizes[MAX_DEVS];
+static int dummy_blk_sizes[MAX_DEVS];
+static unsigned dummy_size = 4096;
+
+MODULE_PARM (dummy_size, "1i");
+
+static int dummy_make_request(request_queue_t *q, int rw, struct buffer_head *bh)
+{
+       u_long start;
+
+       start = bh->b_rsector >> 1;
+
+       if (start + (bh->b_size>>10) > dummy_size) {
+               printk(KERN_ERR DEVICE_NAME ": bad access: block=%ld, count=%d\n",
+                       bh->b_rsector, bh->b_size);
+               goto io_error;
+       }
+
+       bh->b_end_io(bh,1);
+       return 0;
+
+io_error:
+       buffer_IO_error(bh);
+       return 0;
+}
+
+static int dummy_open(struct inode *inode, struct file *filp)
+{
+       MOD_INC_USE_COUNT;
+       return 0;
+}
+
+static int dummy_release(struct inode *inode, struct file *filp)
+{
+       MOD_DEC_USE_COUNT;
+       return 0;     
+}
+
+static int dummy_ioctl(struct inode *inode, struct file *file,
+                    unsigned int cmd, unsigned long arg)
+{
+       if (!capable(CAP_SYS_ADMIN))
+               return -EPERM;
+       if (!inode)
+               return -EINVAL;
+
+       switch (cmd) {
+       case BLKGETSIZE:
+               return put_user(dummy_size << 1, (long *) arg);
+       default:
+               printk(KERN_ERR DEVICE_NAME ": unknown ioctl 0x%x\n", cmd);
+               break;
+       }
+       return -EINVAL;
+}
+
+static struct block_device_operations dummy_fops =
+{
+       open:           dummy_open,
+       release:        dummy_release,
+       ioctl:          dummy_ioctl,
+};
+
+
+static int dummy_init(void)
+{
+       int i;
+
+       if (register_blkdev(MAJOR_NR, DEVICE_NAME, &dummy_fops)) {
+               printk(KERN_ERR DEVICE_NAME ": Unable to register_blkdev(%d)\n", MAJOR_NR);
+               return -EBUSY;
+       }
+
+       blk_queue_make_request(BLK_DEFAULT_QUEUE(MAJOR_NR), dummy_make_request);
+       for (i=0;i<MAX_DEVS;i++) {
+               dummy_blocksizes[i] = DUMMY_BLOCK_SIZE;
+               dummy_blk_sizes[i] = dummy_size;
+       }
+
+       blksize_size[MAJOR_NR] = dummy_blocksizes;
+       blk_size[MAJOR_NR] = dummy_blk_sizes;
+
+       printk(KERN_DEBUG DEVICE_NAME ": dummy initialised size=%dk\n", 
+              dummy_size);
+
+       return 0;
+}
+
+static void __exit dummy_cleanup(void)
+{
+       unregister_blkdev(MAJOR_NR, DEVICE_NAME);
+       printk(KERN_DEBUG DEVICE_NAME ": dummy released\n");
+}
+
+module_init(dummy_init);
+module_exit(dummy_cleanup);
+MODULE_DESCRIPTION("trivial ramdisk");