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![Al Viro](/assets/img/avatar_default.png)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
515 lines
14 KiB
C
515 lines
14 KiB
C
/*
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* ramdisk.c - Multiple RAM disk driver - gzip-loading version - v. 0.8 beta.
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*
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* (C) Chad Page, Theodore Ts'o, et. al, 1995.
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*
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* This RAM disk is designed to have filesystems created on it and mounted
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* just like a regular floppy disk.
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*
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* It also does something suggested by Linus: use the buffer cache as the
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* RAM disk data. This makes it possible to dynamically allocate the RAM disk
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* buffer - with some consequences I have to deal with as I write this.
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*
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* This code is based on the original ramdisk.c, written mostly by
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* Theodore Ts'o (TYT) in 1991. The code was largely rewritten by
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* Chad Page to use the buffer cache to store the RAM disk data in
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* 1995; Theodore then took over the driver again, and cleaned it up
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* for inclusion in the mainline kernel.
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*
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* The original CRAMDISK code was written by Richard Lyons, and
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* adapted by Chad Page to use the new RAM disk interface. Theodore
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* Ts'o rewrote it so that both the compressed RAM disk loader and the
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* kernel decompressor uses the same inflate.c codebase. The RAM disk
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* loader now also loads into a dynamic (buffer cache based) RAM disk,
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* not the old static RAM disk. Support for the old static RAM disk has
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* been completely removed.
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*
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* Loadable module support added by Tom Dyas.
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*
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* Further cleanups by Chad Page (page0588@sundance.sjsu.edu):
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* Cosmetic changes in #ifdef MODULE, code movement, etc.
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* When the RAM disk module is removed, free the protected buffers
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* Default RAM disk size changed to 2.88 MB
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*
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* Added initrd: Werner Almesberger & Hans Lermen, Feb '96
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*
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* 4/25/96 : Made RAM disk size a parameter (default is now 4 MB)
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* - Chad Page
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*
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* Add support for fs images split across >1 disk, Paul Gortmaker, Mar '98
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*
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* Make block size and block size shift for RAM disks a global macro
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* and set blk_size for -ENOSPC, Werner Fink <werner@suse.de>, Apr '99
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*/
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#include <linux/config.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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#include <asm/atomic.h>
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#include <linux/bio.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/init.h>
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#include <linux/devfs_fs_kernel.h>
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#include <linux/pagemap.h>
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#include <linux/blkdev.h>
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#include <linux/genhd.h>
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#include <linux/buffer_head.h> /* for invalidate_bdev() */
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#include <linux/backing-dev.h>
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#include <linux/blkpg.h>
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#include <linux/writeback.h>
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#include <asm/uaccess.h>
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/* Various static variables go here. Most are used only in the RAM disk code.
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*/
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static struct gendisk *rd_disks[CONFIG_BLK_DEV_RAM_COUNT];
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static struct block_device *rd_bdev[CONFIG_BLK_DEV_RAM_COUNT];/* Protected device data */
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static struct request_queue *rd_queue[CONFIG_BLK_DEV_RAM_COUNT];
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/*
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* Parameters for the boot-loading of the RAM disk. These are set by
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* init/main.c (from arguments to the kernel command line) or from the
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* architecture-specific setup routine (from the stored boot sector
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* information).
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*/
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int rd_size = CONFIG_BLK_DEV_RAM_SIZE; /* Size of the RAM disks */
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/*
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* It would be very desirable to have a soft-blocksize (that in the case
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* of the ramdisk driver is also the hardblocksize ;) of PAGE_SIZE because
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* doing that we'll achieve a far better MM footprint. Using a rd_blocksize of
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* BLOCK_SIZE in the worst case we'll make PAGE_SIZE/BLOCK_SIZE buffer-pages
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* unfreeable. With a rd_blocksize of PAGE_SIZE instead we are sure that only
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* 1 page will be protected. Depending on the size of the ramdisk you
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* may want to change the ramdisk blocksize to achieve a better or worse MM
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* behaviour. The default is still BLOCK_SIZE (needed by rd_load_image that
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* supposes the filesystem in the image uses a BLOCK_SIZE blocksize).
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*/
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static int rd_blocksize = BLOCK_SIZE; /* blocksize of the RAM disks */
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/*
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* Copyright (C) 2000 Linus Torvalds.
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* 2000 Transmeta Corp.
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* aops copied from ramfs.
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*/
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/*
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* If a ramdisk page has buffers, some may be uptodate and some may be not.
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* To bring the page uptodate we zero out the non-uptodate buffers. The
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* page must be locked.
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*/
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static void make_page_uptodate(struct page *page)
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{
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if (page_has_buffers(page)) {
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struct buffer_head *bh = page_buffers(page);
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struct buffer_head *head = bh;
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do {
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if (!buffer_uptodate(bh)) {
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memset(bh->b_data, 0, bh->b_size);
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/*
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* akpm: I'm totally undecided about this. The
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* buffer has just been magically brought "up to
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* date", but nobody should want to be reading
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* it anyway, because it hasn't been used for
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* anything yet. It is still in a "not read
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* from disk yet" state.
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*
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* But non-uptodate buffers against an uptodate
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* page are against the rules. So do it anyway.
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*/
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set_buffer_uptodate(bh);
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}
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} while ((bh = bh->b_this_page) != head);
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} else {
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memset(page_address(page), 0, PAGE_CACHE_SIZE);
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}
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flush_dcache_page(page);
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SetPageUptodate(page);
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}
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static int ramdisk_readpage(struct file *file, struct page *page)
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{
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if (!PageUptodate(page))
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make_page_uptodate(page);
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unlock_page(page);
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return 0;
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}
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static int ramdisk_prepare_write(struct file *file, struct page *page,
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unsigned offset, unsigned to)
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{
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if (!PageUptodate(page))
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make_page_uptodate(page);
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return 0;
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}
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static int ramdisk_commit_write(struct file *file, struct page *page,
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unsigned offset, unsigned to)
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{
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set_page_dirty(page);
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return 0;
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}
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/*
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* ->writepage to the the blockdev's mapping has to redirty the page so that the
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* VM doesn't go and steal it. We return WRITEPAGE_ACTIVATE so that the VM
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* won't try to (pointlessly) write the page again for a while.
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*
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* Really, these pages should not be on the LRU at all.
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*/
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static int ramdisk_writepage(struct page *page, struct writeback_control *wbc)
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{
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if (!PageUptodate(page))
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make_page_uptodate(page);
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SetPageDirty(page);
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if (wbc->for_reclaim)
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return WRITEPAGE_ACTIVATE;
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unlock_page(page);
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return 0;
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}
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/*
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* This is a little speedup thing: short-circuit attempts to write back the
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* ramdisk blockdev inode to its non-existent backing store.
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*/
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static int ramdisk_writepages(struct address_space *mapping,
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struct writeback_control *wbc)
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{
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return 0;
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}
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/*
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* ramdisk blockdev pages have their own ->set_page_dirty() because we don't
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* want them to contribute to dirty memory accounting.
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*/
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static int ramdisk_set_page_dirty(struct page *page)
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{
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SetPageDirty(page);
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return 0;
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}
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static struct address_space_operations ramdisk_aops = {
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.readpage = ramdisk_readpage,
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.prepare_write = ramdisk_prepare_write,
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.commit_write = ramdisk_commit_write,
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.writepage = ramdisk_writepage,
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.set_page_dirty = ramdisk_set_page_dirty,
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.writepages = ramdisk_writepages,
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};
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static int rd_blkdev_pagecache_IO(int rw, struct bio_vec *vec, sector_t sector,
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struct address_space *mapping)
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{
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pgoff_t index = sector >> (PAGE_CACHE_SHIFT - 9);
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unsigned int vec_offset = vec->bv_offset;
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int offset = (sector << 9) & ~PAGE_CACHE_MASK;
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int size = vec->bv_len;
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int err = 0;
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do {
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int count;
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struct page *page;
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char *src;
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char *dst;
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count = PAGE_CACHE_SIZE - offset;
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if (count > size)
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count = size;
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size -= count;
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page = grab_cache_page(mapping, index);
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if (!page) {
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err = -ENOMEM;
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goto out;
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}
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if (!PageUptodate(page))
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make_page_uptodate(page);
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index++;
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if (rw == READ) {
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src = kmap_atomic(page, KM_USER0) + offset;
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dst = kmap_atomic(vec->bv_page, KM_USER1) + vec_offset;
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} else {
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src = kmap_atomic(vec->bv_page, KM_USER0) + vec_offset;
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dst = kmap_atomic(page, KM_USER1) + offset;
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}
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offset = 0;
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vec_offset += count;
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memcpy(dst, src, count);
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kunmap_atomic(src, KM_USER0);
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kunmap_atomic(dst, KM_USER1);
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if (rw == READ)
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flush_dcache_page(vec->bv_page);
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else
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set_page_dirty(page);
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unlock_page(page);
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put_page(page);
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} while (size);
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out:
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return err;
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}
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/*
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* Basically, my strategy here is to set up a buffer-head which can't be
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* deleted, and make that my Ramdisk. If the request is outside of the
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* allocated size, we must get rid of it...
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*
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* 19-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Added devfs support
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*
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*/
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static int rd_make_request(request_queue_t *q, struct bio *bio)
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{
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struct block_device *bdev = bio->bi_bdev;
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struct address_space * mapping = bdev->bd_inode->i_mapping;
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sector_t sector = bio->bi_sector;
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unsigned long len = bio->bi_size >> 9;
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int rw = bio_data_dir(bio);
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struct bio_vec *bvec;
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int ret = 0, i;
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if (sector + len > get_capacity(bdev->bd_disk))
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goto fail;
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if (rw==READA)
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rw=READ;
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bio_for_each_segment(bvec, bio, i) {
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ret |= rd_blkdev_pagecache_IO(rw, bvec, sector, mapping);
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sector += bvec->bv_len >> 9;
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}
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if (ret)
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goto fail;
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bio_endio(bio, bio->bi_size, 0);
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return 0;
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fail:
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bio_io_error(bio, bio->bi_size);
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return 0;
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}
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static int rd_ioctl(struct inode *inode, struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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int error;
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struct block_device *bdev = inode->i_bdev;
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if (cmd != BLKFLSBUF)
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return -ENOTTY;
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/*
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* special: we want to release the ramdisk memory, it's not like with
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* the other blockdevices where this ioctl only flushes away the buffer
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* cache
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*/
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error = -EBUSY;
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down(&bdev->bd_sem);
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if (bdev->bd_openers <= 2) {
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truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
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error = 0;
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}
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up(&bdev->bd_sem);
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return error;
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}
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/*
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* This is the backing_dev_info for the blockdev inode itself. It doesn't need
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* writeback and it does not contribute to dirty memory accounting.
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*/
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static struct backing_dev_info rd_backing_dev_info = {
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.ra_pages = 0, /* No readahead */
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.capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK | BDI_CAP_MAP_COPY,
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.unplug_io_fn = default_unplug_io_fn,
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};
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/*
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* This is the backing_dev_info for the files which live atop the ramdisk
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* "device". These files do need writeback and they do contribute to dirty
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* memory accounting.
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*/
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static struct backing_dev_info rd_file_backing_dev_info = {
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.ra_pages = 0, /* No readahead */
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.capabilities = BDI_CAP_MAP_COPY, /* Does contribute to dirty memory */
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.unplug_io_fn = default_unplug_io_fn,
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};
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static int rd_open(struct inode *inode, struct file *filp)
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{
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unsigned unit = iminor(inode);
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if (rd_bdev[unit] == NULL) {
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struct block_device *bdev = inode->i_bdev;
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struct address_space *mapping;
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unsigned bsize;
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gfp_t gfp_mask;
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inode = igrab(bdev->bd_inode);
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rd_bdev[unit] = bdev;
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bdev->bd_openers++;
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bsize = bdev_hardsect_size(bdev);
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bdev->bd_block_size = bsize;
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inode->i_blkbits = blksize_bits(bsize);
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inode->i_size = get_capacity(bdev->bd_disk)<<9;
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mapping = inode->i_mapping;
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mapping->a_ops = &ramdisk_aops;
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mapping->backing_dev_info = &rd_backing_dev_info;
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bdev->bd_inode_backing_dev_info = &rd_file_backing_dev_info;
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/*
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* Deep badness. rd_blkdev_pagecache_IO() needs to allocate
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* pagecache pages within a request_fn. We cannot recur back
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* into the filesytem which is mounted atop the ramdisk, because
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* that would deadlock on fs locks. And we really don't want
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* to reenter rd_blkdev_pagecache_IO when we're already within
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* that function.
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*
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* So we turn off __GFP_FS and __GFP_IO.
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*
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* And to give this thing a hope of working, turn on __GFP_HIGH.
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* Hopefully, there's enough regular memory allocation going on
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* for the page allocator emergency pools to keep the ramdisk
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* driver happy.
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*/
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gfp_mask = mapping_gfp_mask(mapping);
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gfp_mask &= ~(__GFP_FS|__GFP_IO);
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gfp_mask |= __GFP_HIGH;
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mapping_set_gfp_mask(mapping, gfp_mask);
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}
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return 0;
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}
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static struct block_device_operations rd_bd_op = {
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.owner = THIS_MODULE,
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.open = rd_open,
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.ioctl = rd_ioctl,
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};
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/*
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* Before freeing the module, invalidate all of the protected buffers!
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*/
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static void __exit rd_cleanup(void)
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{
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int i;
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for (i = 0; i < CONFIG_BLK_DEV_RAM_COUNT; i++) {
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struct block_device *bdev = rd_bdev[i];
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rd_bdev[i] = NULL;
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if (bdev) {
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invalidate_bdev(bdev, 1);
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blkdev_put(bdev);
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}
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del_gendisk(rd_disks[i]);
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put_disk(rd_disks[i]);
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blk_cleanup_queue(rd_queue[i]);
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}
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devfs_remove("rd");
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unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
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}
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/*
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* This is the registration and initialization section of the RAM disk driver
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*/
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static int __init rd_init(void)
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{
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int i;
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int err = -ENOMEM;
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if (rd_blocksize > PAGE_SIZE || rd_blocksize < 512 ||
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(rd_blocksize & (rd_blocksize-1))) {
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printk("RAMDISK: wrong blocksize %d, reverting to defaults\n",
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rd_blocksize);
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rd_blocksize = BLOCK_SIZE;
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}
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for (i = 0; i < CONFIG_BLK_DEV_RAM_COUNT; i++) {
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rd_disks[i] = alloc_disk(1);
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if (!rd_disks[i])
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goto out;
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}
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if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) {
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err = -EIO;
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goto out;
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}
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devfs_mk_dir("rd");
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for (i = 0; i < CONFIG_BLK_DEV_RAM_COUNT; i++) {
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struct gendisk *disk = rd_disks[i];
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rd_queue[i] = blk_alloc_queue(GFP_KERNEL);
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if (!rd_queue[i])
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goto out_queue;
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blk_queue_make_request(rd_queue[i], &rd_make_request);
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blk_queue_hardsect_size(rd_queue[i], rd_blocksize);
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/* rd_size is given in kB */
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disk->major = RAMDISK_MAJOR;
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disk->first_minor = i;
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disk->fops = &rd_bd_op;
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disk->queue = rd_queue[i];
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disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
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sprintf(disk->disk_name, "ram%d", i);
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sprintf(disk->devfs_name, "rd/%d", i);
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set_capacity(disk, rd_size * 2);
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add_disk(rd_disks[i]);
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}
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/* rd_size is given in kB */
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printk("RAMDISK driver initialized: "
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"%d RAM disks of %dK size %d blocksize\n",
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CONFIG_BLK_DEV_RAM_COUNT, rd_size, rd_blocksize);
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return 0;
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out_queue:
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unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
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out:
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while (i--) {
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put_disk(rd_disks[i]);
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blk_cleanup_queue(rd_queue[i]);
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}
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return err;
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}
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module_init(rd_init);
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module_exit(rd_cleanup);
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/* options - nonmodular */
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#ifndef MODULE
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static int __init ramdisk_size(char *str)
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{
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rd_size = simple_strtol(str,NULL,0);
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return 1;
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}
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static int __init ramdisk_size2(char *str) /* kludge */
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{
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return ramdisk_size(str);
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}
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|
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");
|