/*
* 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/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/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 = CONFIG_BLK_DEV_RAM_BLOCKSIZE;
/*
* 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 blockdev's mapping has to redirty the page so that the
* VM doesn't go and steal it. We return AOP_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 AOP_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)
{
if (!TestSetPageDirty(page))
return 1;
return 0;
}
/*
* releasepage is called by pagevec_strip/try_to_release_page if
* buffers_heads_over_limit is true. Without a releasepage function
* try_to_free_buffers is called instead. That can unset the dirty
* bit of our ram disk pages, which will be eventually freed, even
* if the page is still in use.
*/
static int ramdisk_releasepage(struct page *page, gfp_t dummy)
{
return 0;
}
static const 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,
.releasepage = ramdisk_releasepage,
};
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(struct request_queue *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, 0);
return 0;
fail:
bio_io_error(bio);
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;
mutex_lock(&bdev->bd_mutex);
if (bdev->bd_openers <= 2) {
truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
error = 0;
}
mutex_unlock(&bdev->bd_mutex);
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;
gfp_t 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 filesystem 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);
blkdev_put(bdev);
}
del_gendisk(rd_disks[i]);
put_disk(rd_disks[i]);
blk_cleanup_queue(rd_queue[i]);
}
unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
bdi_destroy(&rd_file_backing_dev_info);
bdi_destroy(&rd_backing_dev_info);
}
/*
* This is the registration and initialization section of the RAM disk driver
*/
static int __init rd_init(void)
{
int i;
int err;
err = bdi_init(&rd_backing_dev_info);
if (err)
goto out2;
err = bdi_init(&rd_file_backing_dev_info);
if (err) {
bdi_destroy(&rd_backing_dev_info);
goto out2;
}
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;
rd_queue[i] = blk_alloc_queue(GFP_KERNEL);
if (!rd_queue[i]) {
put_disk(rd_disks[i]);
goto out;
}
}
if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) {
err = -EIO;
goto out;
}
for (i = 0; i < CONFIG_BLK_DEV_RAM_COUNT; i++) {
struct gendisk *disk = rd_disks[i];
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);
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:
while (i--) {
put_disk(rd_disks[i]);
blk_cleanup_queue(rd_queue[i]);
}
bdi_destroy(&rd_backing_dev_info);
bdi_destroy(&rd_file_backing_dev_info);
out2:
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_blocksize(char *str)
{
rd_blocksize = simple_strtol(str,NULL,0);
return 1;
}
__setup("ramdisk_size=", ramdisk_size);
__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");
