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-rw-r--r--drivers/block/rd.c515
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diff --git a/drivers/block/rd.c b/drivers/block/rd.c
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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 <asm/atomic.h>
+#include <linux/bio.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/devfs_fs_kernel.h>
+#include <linux/pagemap.h>
+#include <linux/blkdev.h>
+#include <linux/genhd.h>
+#include <linux/buffer_head.h> /* for invalidate_bdev() */
+#include <linux/backing-dev.h>
+#include <linux/blkpg.h>
+#include <linux/writeback.h>
+
+#include <asm/uaccess.h>
+
+/* Various static variables go here. Most are used only in the RAM disk code.
+ */
+
+static struct gendisk *rd_disks[CONFIG_BLK_DEV_RAM_COUNT];
+static struct block_device *rd_bdev[CONFIG_BLK_DEV_RAM_COUNT];/* Protected device data */
+static struct request_queue *rd_queue[CONFIG_BLK_DEV_RAM_COUNT];
+
+/*
+ * 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).
+ */
+static int rd_blocksize = BLOCK_SIZE; /* blocksize of the RAM disks */
+
+/*
+ * Copyright (C) 2000 Linus Torvalds.
+ * 2000 Transmeta Corp.
+ * aops copied from ramfs.
+ */
+
+/*
+ * If a ramdisk page has buffers, some may be uptodate and some may be not.
+ * To bring the page uptodate we zero out the non-uptodate buffers. The
+ * page must be locked.
+ */
+static void make_page_uptodate(struct page *page)
+{
+ if (page_has_buffers(page)) {
+ struct buffer_head *bh = page_buffers(page);
+ struct buffer_head *head = bh;
+
+ do {
+ if (!buffer_uptodate(bh)) {
+ memset(bh->b_data, 0, bh->b_size);
+ /*
+ * akpm: I'm totally undecided about this. The
+ * buffer has just been magically brought "up to
+ * date", but nobody should want to be reading
+ * it anyway, because it hasn't been used for
+ * anything yet. It is still in a "not read
+ * from disk yet" state.
+ *
+ * But non-uptodate buffers against an uptodate
+ * page are against the rules. So do it anyway.
+ */
+ set_buffer_uptodate(bh);
+ }
+ } while ((bh = bh->b_this_page) != head);
+ } else {
+ memset(page_address(page), 0, PAGE_CACHE_SIZE);
+ }
+ flush_dcache_page(page);
+ SetPageUptodate(page);
+}
+
+static int ramdisk_readpage(struct file *file, struct page *page)
+{
+ if (!PageUptodate(page))
+ make_page_uptodate(page);
+ unlock_page(page);
+ return 0;
+}
+
+static int ramdisk_prepare_write(struct file *file, struct page *page,
+ unsigned offset, unsigned to)
+{
+ if (!PageUptodate(page))
+ make_page_uptodate(page);
+ return 0;
+}
+
+static int ramdisk_commit_write(struct file *file, struct page *page,
+ unsigned offset, unsigned to)
+{
+ set_page_dirty(page);
+ return 0;
+}
+
+/*
+ * ->writepage to the the blockdev's mapping has to redirty the page so that the
+ * VM doesn't go and steal it. We return WRITEPAGE_ACTIVATE so that the VM
+ * won't try to (pointlessly) write the page again for a while.
+ *
+ * Really, these pages should not be on the LRU at all.
+ */
+static int ramdisk_writepage(struct page *page, struct writeback_control *wbc)
+{
+ if (!PageUptodate(page))
+ make_page_uptodate(page);
+ SetPageDirty(page);
+ if (wbc->for_reclaim)
+ return WRITEPAGE_ACTIVATE;
+ unlock_page(page);
+ return 0;
+}
+
+/*
+ * This is a little speedup thing: short-circuit attempts to write back the
+ * ramdisk blockdev inode to its non-existent backing store.
+ */
+static int ramdisk_writepages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ return 0;
+}
+
+/*
+ * ramdisk blockdev pages have their own ->set_page_dirty() because we don't
+ * want them to contribute to dirty memory accounting.
+ */
+static int ramdisk_set_page_dirty(struct page *page)
+{
+ SetPageDirty(page);
+ return 0;
+}
+
+static struct address_space_operations ramdisk_aops = {
+ .readpage = ramdisk_readpage,
+ .prepare_write = ramdisk_prepare_write,
+ .commit_write = ramdisk_commit_write,
+ .writepage = ramdisk_writepage,
+ .set_page_dirty = ramdisk_set_page_dirty,
+ .writepages = ramdisk_writepages,
+};
+
+static int rd_blkdev_pagecache_IO(int rw, struct bio_vec *vec, sector_t sector,
+ struct address_space *mapping)
+{
+ pgoff_t index = sector >> (PAGE_CACHE_SHIFT - 9);
+ unsigned int vec_offset = vec->bv_offset;
+ int offset = (sector << 9) & ~PAGE_CACHE_MASK;
+ int size = vec->bv_len;
+ int err = 0;
+
+ do {
+ int count;
+ struct page *page;
+ char *src;
+ char *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;
+ }
+
+ if (!PageUptodate(page))
+ make_page_uptodate(page);
+
+ index++;
+
+ if (rw == READ) {
+ src = kmap_atomic(page, KM_USER0) + offset;
+ dst = kmap_atomic(vec->bv_page, KM_USER1) + vec_offset;
+ } else {
+ src = kmap_atomic(vec->bv_page, KM_USER0) + vec_offset;
+ dst = kmap_atomic(page, KM_USER1) + offset;
+ }
+ offset = 0;
+ vec_offset += count;
+
+ memcpy(dst, src, count);
+
+ kunmap_atomic(src, KM_USER0);
+ kunmap_atomic(dst, KM_USER1);
+
+ if (rw == READ)
+ flush_dcache_page(vec->bv_page);
+ else
+ set_page_dirty(page);
+ unlock_page(page);
+ put_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, struct bio *bio)
+{
+ struct block_device *bdev = bio->bi_bdev;
+ struct address_space * mapping = bdev->bd_inode->i_mapping;
+ sector_t sector = bio->bi_sector;
+ unsigned long len = bio->bi_size >> 9;
+ int rw = bio_data_dir(bio);
+ struct bio_vec *bvec;
+ int ret = 0, i;
+
+ if (sector + len > get_capacity(bdev->bd_disk))
+ goto fail;
+
+ if (rw==READA)
+ rw=READ;
+
+ bio_for_each_segment(bvec, bio, i) {
+ ret |= rd_blkdev_pagecache_IO(rw, bvec, sector, mapping);
+ sector += bvec->bv_len >> 9;
+ }
+ if (ret)
+ goto fail;
+
+ bio_endio(bio, bio->bi_size, 0);
+ return 0;
+fail:
+ bio_io_error(bio, bio->bi_size);
+ return 0;
+}
+
+static int rd_ioctl(struct inode *inode, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ int error;
+ struct block_device *bdev = inode->i_bdev;
+
+ if (cmd != BLKFLSBUF)
+ return -ENOTTY;
+
+ /*
+ * 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(&bdev->bd_sem);
+ if (bdev->bd_openers <= 2) {
+ truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
+ error = 0;
+ }
+ up(&bdev->bd_sem);
+ return error;
+}
+
+/*
+ * This is the backing_dev_info for the blockdev inode itself. It doesn't need
+ * writeback and it does not contribute to dirty memory accounting.
+ */
+static struct backing_dev_info rd_backing_dev_info = {
+ .ra_pages = 0, /* No readahead */
+ .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK | BDI_CAP_MAP_COPY,
+ .unplug_io_fn = default_unplug_io_fn,
+};
+
+/*
+ * This is the backing_dev_info for the files which live atop the ramdisk
+ * "device". These files do need writeback and they do contribute to dirty
+ * memory accounting.
+ */
+static struct backing_dev_info rd_file_backing_dev_info = {
+ .ra_pages = 0, /* No readahead */
+ .capabilities = BDI_CAP_MAP_COPY, /* Does contribute to dirty memory */
+ .unplug_io_fn = default_unplug_io_fn,
+};
+
+static int rd_open(struct inode *inode, struct file *filp)
+{
+ unsigned unit = iminor(inode);
+
+ if (rd_bdev[unit] == NULL) {
+ struct block_device *bdev = inode->i_bdev;
+ struct address_space *mapping;
+ unsigned bsize;
+ int gfp_mask;
+
+ inode = igrab(bdev->bd_inode);
+ rd_bdev[unit] = bdev;
+ bdev->bd_openers++;
+ bsize = bdev_hardsect_size(bdev);
+ bdev->bd_block_size = bsize;
+ inode->i_blkbits = blksize_bits(bsize);
+ inode->i_size = get_capacity(bdev->bd_disk)<<9;
+
+ mapping = inode->i_mapping;
+ mapping->a_ops = &ramdisk_aops;
+ mapping->backing_dev_info = &rd_backing_dev_info;
+ bdev->bd_inode_backing_dev_info = &rd_file_backing_dev_info;
+
+ /*
+ * Deep badness. rd_blkdev_pagecache_IO() needs to allocate
+ * pagecache pages within a request_fn. We cannot recur back
+ * into the filesytem which is mounted atop the ramdisk, because
+ * that would deadlock on fs locks. And we really don't want
+ * to reenter rd_blkdev_pagecache_IO when we're already within
+ * that function.
+ *
+ * So we turn off __GFP_FS and __GFP_IO.
+ *
+ * And to give this thing a hope of working, turn on __GFP_HIGH.
+ * Hopefully, there's enough regular memory allocation going on
+ * for the page allocator emergency pools to keep the ramdisk
+ * driver happy.
+ */
+ gfp_mask = mapping_gfp_mask(mapping);
+ gfp_mask &= ~(__GFP_FS|__GFP_IO);
+ gfp_mask |= __GFP_HIGH;
+ mapping_set_gfp_mask(mapping, gfp_mask);
+ }
+
+ 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 < CONFIG_BLK_DEV_RAM_COUNT; i++) {
+ struct block_device *bdev = rd_bdev[i];
+ rd_bdev[i] = NULL;
+ if (bdev) {
+ invalidate_bdev(bdev, 1);
+ blkdev_put(bdev);
+ }
+ del_gendisk(rd_disks[i]);
+ put_disk(rd_disks[i]);
+ blk_cleanup_queue(rd_queue[i]);
+ }
+ devfs_remove("rd");
+ unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
+}
+
+/*
+ * This is the registration and initialization section of the RAM disk driver
+ */
+static int __init rd_init(void)
+{
+ int i;
+ int err = -ENOMEM;
+
+ 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;
+ }
+
+ for (i = 0; i < CONFIG_BLK_DEV_RAM_COUNT; i++) {
+ rd_disks[i] = alloc_disk(1);
+ if (!rd_disks[i])
+ goto out;
+ }
+
+ if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) {
+ err = -EIO;
+ goto out;
+ }
+
+ devfs_mk_dir("rd");
+
+ for (i = 0; i < CONFIG_BLK_DEV_RAM_COUNT; i++) {
+ struct gendisk *disk = rd_disks[i];
+
+ rd_queue[i] = blk_alloc_queue(GFP_KERNEL);
+ if (!rd_queue[i])
+ goto out_queue;
+
+ blk_queue_make_request(rd_queue[i], &rd_make_request);
+ blk_queue_hardsect_size(rd_queue[i], rd_blocksize);
+
+ /* rd_size is given in kB */
+ disk->major = RAMDISK_MAJOR;
+ disk->first_minor = i;
+ disk->fops = &rd_bd_op;
+ disk->queue = rd_queue[i];
+ disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
+ sprintf(disk->disk_name, "ram%d", i);
+ sprintf(disk->devfs_name, "rd/%d", i);
+ set_capacity(disk, rd_size * 2);
+ add_disk(rd_disks[i]);
+ }
+
+ /* rd_size is given in kB */
+ printk("RAMDISK driver initialized: "
+ "%d RAM disks of %dK size %d blocksize\n",
+ CONFIG_BLK_DEV_RAM_COUNT, rd_size, rd_blocksize);
+
+ return 0;
+out_queue:
+ unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
+out:
+ while (i--) {
+ put_disk(rd_disks[i]);
+ blk_cleanup_queue(rd_queue[i]);
+ }
+ return err;
+}
+
+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_param(rd_size, int, 0);
+MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");
+module_param(rd_blocksize, int, 0);
+MODULE_PARM_DESC(rd_blocksize, "Blocksize of each RAM disk in bytes.");
+MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);
+
+MODULE_LICENSE("GPL");
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