1 files changed, 515 insertions, 0 deletions

diff --git a/drivers/block/rd.c b/drivers/block/rd.c
new file mode 100644
index 000000000000..145c1fbffe01
--- /dev/null
+++ b/drivers/block/rd.c
@@ -0,0 +1,515 @@
+/*
+ * 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");