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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [drivers/] [block/] [rd.c] - Rev 1275
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/* * 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");
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