text: /*
   * ramdisk.c - Multiple RAM disk driver - gzip-loading version - v. 0.8 beta.
   * 
   * (C) Chad Page, Theodore Ts'o, et. al, 1995. 
   *
   * This RAM disk is designed to have filesystems created on it and mounted
   * just like a regular floppy disk.  
   *  
   * It also does something suggested by Linus: use the buffer cache as the
   * RAM disk data.  This makes it possible to dynamically allocate the RAM disk
   * buffer - with some consequences I have to deal with as I write this. 
   * 
   * This code is based on the original ramdisk.c, written mostly by
   * Theodore Ts'o (TYT) in 1991.  The code was largely rewritten by
   * Chad Page to use the buffer cache to store the RAM disk data in
   * 1995; Theodore then took over the driver again, and cleaned it up
   * for inclusion in the mainline kernel.
   *
   * The original CRAMDISK code was written by Richard Lyons, and
   * adapted by Chad Page to use the new RAM disk interface.  Theodore
   * Ts'o rewrote it so that both the compressed RAM disk loader and the
   * kernel decompressor uses the same inflate.c codebase.  The RAM disk
   * loader now also loads into a dynamic (buffer cache based) RAM disk,
   * not the old static RAM disk.  Support for the old static RAM disk has
   * been completely removed.
   *
   * Loadable module support added by Tom Dyas.
   *
   * Further cleanups by Chad Page (page0588@sundance.sjsu.edu):
   *	Cosmetic changes in #ifdef MODULE, code movement, etc.
   * 	When the RAM disk module is removed, free the protected buffers
   * 	Default RAM disk size changed to 2.88 MB
   *
   *  Added initrd: Werner Almesberger & Hans Lermen, Feb '96
   *
   * 4/25/96 : Made RAM disk size a parameter (default is now 4 MB) 
   *		- Chad Page
   *
   * Add support for fs images split across >1 disk, Paul Gortmaker, Mar '98
   *
   * Make block size and block size shift for RAM disks a global macro
   * and set blk_size for -ENOSPC,     Werner Fink <werner@suse.de>, Apr '99
   */
  
  #include <linux/config.h>
  #include <linux/string.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/devfs_fs_kernel.h>
  #include <linux/smp_lock.h>
  #include <asm/uaccess.h>
  
  /*
   * 35 has been officially registered as the RAMDISK major number, but
   * so is the original MAJOR number of 1.  We're using 1 in
   * include/linux/major.h for now
   */
  #define MAJOR_NR RAMDISK_MAJOR
  #include <linux/blk.h>
  #include <linux/blkpg.h>
  
  /* The RAM disk size is now a parameter */
  #define NUM_RAMDISKS 16		/* This cannot be overridden (yet) */ 
  
  #ifdef CONFIG_BLK_DEV_INITRD
  static int initrd_users;
  unsigned long initrd_start, initrd_end;
  int initrd_below_start_ok;
  #endif
  
  /* Various static variables go here.  Most are used only in the RAM disk code.
   */
  
  static unsigned long rd_length[NUM_RAMDISKS];	/* Size of RAM disks in bytes   */
  static int rd_hardsec[NUM_RAMDISKS];		/* Size of real blocks in bytes */
  static int rd_blocksizes[NUM_RAMDISKS];		/* Size of 1024 byte blocks :)  */
  static int rd_kbsize[NUM_RAMDISKS];		/* Size in blocks of 1024 bytes */
  static devfs_handle_t devfs_handle;
  static struct block_device *rd_bdev[NUM_RAMDISKS];/* Protected device data */
  
  /*
   * Parameters for the boot-loading of the RAM disk.  These are set by
   * init/main.c (from arguments to the kernel command line) or from the
   * architecture-specific setup routine (from the stored boot sector
   * information). 
   */
  int rd_size = CONFIG_BLK_DEV_RAM_SIZE;		/* Size of the RAM disks */
  /*
   * It would be very desirable to have a soft-blocksize (that in the case
   * of the ramdisk driver is also the hardblocksize ;) of PAGE_SIZE because
   * doing that we'll achieve a far better MM footprint. Using a rd_blocksize of
   * BLOCK_SIZE in the worst case we'll make PAGE_SIZE/BLOCK_SIZE buffer-pages
   * unfreeable. With a rd_blocksize of PAGE_SIZE instead we are sure that only
   * 1 page will be protected. Depending on the size of the ramdisk you
   * may want to change the ramdisk blocksize to achieve a better or worse MM
   * behaviour. The default is still BLOCK_SIZE (needed by rd_load_image that
   * supposes the filesystem in the image uses a BLOCK_SIZE blocksize).
   */
  int rd_blocksize = BLOCK_SIZE;			/* blocksize of the RAM disks */
  
  /*
   * Copyright (C) 2000 Linus Torvalds.
   *               2000 Transmeta Corp.
   * aops copied from ramfs.
   */
  static void ramdisk_updatepage(struct page * page, int need_kmap)
  {
  	if (!Page_Uptodate(page)) {
  		struct buffer_head *bh = page->buffers;
  		void * address;
  
  		if (need_kmap)
  			kmap(page);
  		address = page_address(page);
  		if (bh) {
  			struct buffer_head *tmp = bh;
  			do {
  				if (!buffer_uptodate(tmp)) {
  					memset(address, 0, tmp->b_size);
  					mark_buffer_uptodate(tmp, 1);
  				}
  				address += tmp->b_size;
  				tmp = tmp->b_this_page;
  			} while (tmp != bh);
  		} else
  			memset(address, 0, PAGE_CACHE_SIZE);
  		if (need_kmap)
  			kunmap(page);
  		flush_dcache_page(page);
  		SetPageUptodate(page);
  	}
  }
  
  static int ramdisk_readpage(struct file *file, struct page * page)
  {
  	ramdisk_updatepage(page, 1);
  	UnlockPage(page);
  	return 0;
  }
  
  static int ramdisk_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
  {
  	ramdisk_updatepage(page, 0);
  	SetPageDirty(page);
  	return 0;
  }
  
  static int ramdisk_commit_write(struct file *file, struct page *page, unsigned offset, unsigned to)
  {
  	return 0;
  }
  
  static struct address_space_operations ramdisk_aops = {
  	readpage: ramdisk_readpage,
  	writepage: fail_writepage,
  	prepare_write: ramdisk_prepare_write,
  	commit_write: ramdisk_commit_write,
  };
  
  static int rd_blkdev_pagecache_IO(int rw, struct buffer_head * sbh, int minor)
  {
  	struct address_space * mapping;
  	unsigned long index;
  	int offset, size, err;
  
  	err = 0;
  	mapping = rd_bdev[minor]->bd_inode->i_mapping;
  
  	/* writing a buffer cache not uptodate must not clear it */
  	if (sbh->b_page->mapping == mapping) {
  		if (rw == WRITE) {
  			mark_buffer_uptodate(sbh, 1);
  			SetPageDirty(sbh->b_page);
  		}
  		goto out;
  	}
  
  	index = sbh->b_rsector >> (PAGE_CACHE_SHIFT - 9);
  	offset = (sbh->b_rsector << 9) & ~PAGE_CACHE_MASK;
  	size = sbh->b_size;
  
  	do {
  		int count;
  		struct page * page;
  		char * src, * dst;
  
  		count = PAGE_CACHE_SIZE - offset;
  		if (count > size)
  			count = size;
  		size -= count;
  
  		page = grab_cache_page(mapping, index);
  		if (!page) {
  			err = -ENOMEM;
  			goto out;
  		}
  
  		ramdisk_updatepage(page, 1);
  
  		index++;
  
  		if (rw == READ) {
  			src = kmap(page);
  			src += offset;
  			dst = bh_kmap(sbh);
  		} else {
  			dst = kmap(page);
  			dst += offset;
  			src = bh_kmap(sbh);
  		}
  		offset = 0;
  
  		memcpy(dst, src, count);
  
  		kunmap(page);
  		bh_kunmap(sbh);
  
  		if (rw == READ) {
  			flush_dcache_page(sbh->b_page);
  		} else {
  			SetPageDirty(page);
  		}
  		UnlockPage(page);
  		__free_page(page);
  	} while (size);
  
   out:
  	return err;
  }
  
  /*
   *  Basically, my strategy here is to set up a buffer-head which can't be
   *  deleted, and make that my Ramdisk.  If the request is outside of the
   *  allocated size, we must get rid of it...
   *
   * 19-JAN-1998  Richard Gooch <rgooch@atnf.csiro.au>  Added devfs support
   *
   */
  static int rd_make_request(request_queue_t * q, int rw, struct buffer_head *sbh)
  {
  	unsigned int minor;
  	unsigned long offset, len;
  
  	minor = MINOR(sbh->b_rdev);
  
  	if (minor >= NUM_RAMDISKS)
  		goto fail;
  
  	
  	offset = sbh->b_rsector << 9;
  	len = sbh->b_size;
  
  	if ((offset + len) > rd_length[minor])
  		goto fail;
  
  	if (rw==READA)
  		rw=READ;
  	if ((rw != READ) && (rw != WRITE)) {
  		printk(KERN_INFO "RAMDISK: bad command: %d\n", rw);
  		goto fail;
  	}
  
  	if (rd_blkdev_pagecache_IO(rw, sbh, minor))
  		goto fail;
  
  	sbh->b_end_io(sbh,1);
  	return 0;
   fail:
  	buffer_IO_error(sbh);
  	return 0;
  } 
  
  static int rd_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
  {
  	int error = -EINVAL;
  	unsigned int minor;
  
  	if (!inode || !inode->i_rdev) 	
  		goto out;
  
  	minor = MINOR(inode->i_rdev);
  
  	switch (cmd) {
  		case BLKFLSBUF:
  			if (!capable(CAP_SYS_ADMIN))
  				return -EACCES;
  			/* special: we want to release the ramdisk memory,
  			   it's not like with the other blockdevices where
  			   this ioctl only flushes away the buffer cache. */
  			error = -EBUSY;
  			down(&inode->i_bdev->bd_sem);
  			if (inode->i_bdev->bd_openers <= 2) {
  				truncate_inode_pages(inode->i_mapping, 0);
  				error = 0;
  			}
  			up(&inode->i_bdev->bd_sem);
  			invalidate_buffers(inode->i_rdev);
  			break;
           	case BLKGETSIZE:   /* Return device size */
  			if (!arg)
  				break;
  			error = put_user(rd_kbsize[minor] << 1, (unsigned long *) arg);
  			break;
           	case BLKGETSIZE64:
  			error = put_user((u64)rd_kbsize[minor]<<10, (u64*)arg);
  			break;
  		case BLKROSET:
  		case BLKROGET:
  		case BLKSSZGET:
  			error = blk_ioctl(inode->i_rdev, cmd, arg);
  	};
  out:
  	return error;
  }
  
  
  #ifdef CONFIG_BLK_DEV_INITRD
  
  static ssize_t initrd_read(struct file *file, char *buf,
  			   size_t count, loff_t *ppos)
  {
  	int left;
  
  	left = initrd_end - initrd_start - *ppos;
  	if (count > left) count = left;
  	if (count == 0) return 0;
  	if (copy_to_user(buf, (char *)initrd_start + *ppos, count))
  		return -EFAULT;
  	*ppos += count;
  	return count;
  }
  
  
  static int initrd_release(struct inode *inode,struct file *file)
  {
  	extern void free_initrd_mem(unsigned long, unsigned long);
  
  	lock_kernel();
  	if (!--initrd_users) {
  		free_initrd_mem(initrd_start, initrd_end);
  		initrd_start = 0;
  	}
  	unlock_kernel();
  	blkdev_put(inode->i_bdev, BDEV_FILE);
  	return 0;
  }
  
  
  static struct file_operations initrd_fops = {
  	read:		initrd_read,
  	release:	initrd_release,
  };
  
  #endif
  
  
  static int rd_open(struct inode * inode, struct file * filp)
  {
  	int unit = DEVICE_NR(inode->i_rdev);
  
  #ifdef CONFIG_BLK_DEV_INITRD
  	if (unit == INITRD_MINOR) {
  		if (!initrd_start) return -ENODEV;
  		initrd_users++;
  		filp->f_op = &initrd_fops;
  		return 0;
  	}
  #endif
  
  	if (unit >= NUM_RAMDISKS)
  		return -ENXIO;
  
  	/*
  	 * Immunize device against invalidate_buffers() and prune_icache().
  	 */
  	if (rd_bdev[unit] == NULL) {
  		rd_bdev[unit] = bdget(kdev_t_to_nr(inode->i_rdev));
  		rd_bdev[unit]->bd_openers++;
  		rd_bdev[unit]->bd_inode->i_mapping->a_ops = &ramdisk_aops;
  	}
  
  	return 0;
  }
  
  static struct block_device_operations rd_bd_op = {
  	owner:		THIS_MODULE,
  	open:		rd_open,
  	ioctl:		rd_ioctl,
  };
  
  /* Before freeing the module, invalidate all of the protected buffers! */
  static void __exit rd_cleanup (void)
  {
  	int i;
  
  	for (i = 0 ; i < NUM_RAMDISKS; i++) {
  		struct block_device *bdev = rd_bdev[i];
  		rd_bdev[i] = NULL;
  		if (bdev)
  			blkdev_put(bdev, BDEV_FILE);
  		destroy_buffers(MKDEV(MAJOR_NR, i));
  	}
  
  	devfs_unregister (devfs_handle);
  	unregister_blkdev( MAJOR_NR, "ramdisk" );
  	hardsect_size[MAJOR_NR] = NULL;
  	blksize_size[MAJOR_NR] = NULL;
  	blk_size[MAJOR_NR] = NULL;
  }
  
  /* This is the registration and initialization section of the RAM disk driver */
  static int __init rd_init (void)
  {
  	int		i;
  
  	if (rd_blocksize > PAGE_SIZE || rd_blocksize < 512 ||
  	    (rd_blocksize & (rd_blocksize-1)))
  	{
  		printk("RAMDISK: wrong blocksize %d, reverting to defaults\n",
  		       rd_blocksize);
  		rd_blocksize = BLOCK_SIZE;
  	}
  
  	if (register_blkdev(MAJOR_NR, "ramdisk", &rd_bd_op)) {
  		printk("RAMDISK: Could not get major %d", MAJOR_NR);
  		return -EIO;
  	}
  
  	blk_queue_make_request(BLK_DEFAULT_QUEUE(MAJOR_NR), &rd_make_request);
  
  	for (i = 0; i < NUM_RAMDISKS; i++) {
  		/* rd_size is given in kB */
  		rd_length[i] = rd_size << 10;
  		rd_hardsec[i] = rd_blocksize;
  		rd_blocksizes[i] = rd_blocksize;
  		rd_kbsize[i] = rd_size;
  	}
  	devfs_handle = devfs_mk_dir (NULL, "rd", NULL);
  	devfs_register_series (devfs_handle, "%u", NUM_RAMDISKS,
  			       DEVFS_FL_DEFAULT, MAJOR_NR, 0,
  			       S_IFBLK | S_IRUSR | S_IWUSR,
  			       &rd_bd_op, NULL);
  
  	for (i = 0; i < NUM_RAMDISKS; i++)
  		register_disk(NULL, MKDEV(MAJOR_NR,i), 1, &rd_bd_op, rd_size<<1);
  
  #ifdef CONFIG_BLK_DEV_INITRD
  	/* We ought to separate initrd operations here */
  	register_disk(NULL, MKDEV(MAJOR_NR,INITRD_MINOR), 1, &rd_bd_op, rd_size<<1);
  	devfs_register(devfs_handle, "initrd", DEVFS_FL_DEFAULT, MAJOR_NR,
  			INITRD_MINOR, S_IFBLK | S_IRUSR, &rd_bd_op, NULL);
  #endif
  
  	hardsect_size[MAJOR_NR] = rd_hardsec;		/* Size of the RAM disk blocks */
  	blksize_size[MAJOR_NR] = rd_blocksizes;		/* Avoid set_blocksize() check */
  	blk_size[MAJOR_NR] = rd_kbsize;			/* Size of the RAM disk in kB  */
  
  		/* rd_size is given in kB */
  	printk("RAMDISK driver initialized: "
  	       "%d RAM disks of %dK size %d blocksize\n",
  	       NUM_RAMDISKS, rd_size, rd_blocksize);
  
  	return 0;
  }
  
  module_init(rd_init);
  module_exit(rd_cleanup);
  
  /* options - nonmodular */
  #ifndef MODULE
  static int __init ramdisk_size(char *str)
  {
  	rd_size = simple_strtol(str,NULL,0);
  	return 1;
  }
  static int __init ramdisk_size2(char *str)	/* kludge */
  {
  	return ramdisk_size(str);
  }
  static int __init ramdisk_blocksize(char *str)
  {
  	rd_blocksize = simple_strtol(str,NULL,0);
  	return 1;
  }
  __setup("ramdisk=", ramdisk_size);
  __setup("ramdisk_size=", ramdisk_size2);
  __setup("ramdisk_blocksize=", ramdisk_blocksize);
  #endif
  
  /* options - modular */
  MODULE_PARM     (rd_size, "1i");
  MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");
  MODULE_PARM     (rd_blocksize, "i");
  MODULE_PARM_DESC(rd_blocksize, "Blocksize of each RAM disk in bytes.");
  
  MODULE_LICENSE("GPL");
  