diff options
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/Kconfig | 12 | ||||
| -rw-r--r-- | drivers/block/Makefile | 2 | ||||
| -rw-r--r-- | drivers/block/brd.c | 548 | ||||
| -rw-r--r-- | drivers/block/rd.c | 537 |
4 files changed, 550 insertions, 549 deletions
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index 64e5148..8be67cd 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -322,7 +322,7 @@ config BLK_DEV_UB If unsure, say N. config BLK_DEV_RAM - tristate "RAM disk support" + tristate "RAM block device support" ---help--- Saying Y here will allow you to use a portion of your RAM memory as a block device, so that you can make file systems on it, read and @@ -357,16 +357,6 @@ config BLK_DEV_RAM_SIZE The default value is 4096 kilobytes. Only change this if you know what you are doing. -config BLK_DEV_RAM_BLOCKSIZE - int "Default RAM disk block size (bytes)" - depends on BLK_DEV_RAM - default "1024" - help - The default value is 1024 bytes. PAGE_SIZE is a much more - efficient choice however. The default is kept to ensure initrd - setups function - apparently needed by the rd_load_image routine - that supposes the filesystem in the image uses a 1024 blocksize. - config CDROM_PKTCDVD tristate "Packet writing on CD/DVD media" depends on !UML diff --git a/drivers/block/Makefile b/drivers/block/Makefile index 7691505..01c9724 100644 --- a/drivers/block/Makefile +++ b/drivers/block/Makefile @@ -11,7 +11,7 @@ obj-$(CONFIG_AMIGA_FLOPPY) += amiflop.o obj-$(CONFIG_PS3_DISK) += ps3disk.o obj-$(CONFIG_ATARI_FLOPPY) += ataflop.o obj-$(CONFIG_AMIGA_Z2RAM) += z2ram.o -obj-$(CONFIG_BLK_DEV_RAM) += rd.o +obj-$(CONFIG_BLK_DEV_RAM) += brd.o obj-$(CONFIG_BLK_DEV_LOOP) += loop.o obj-$(CONFIG_BLK_DEV_PS2) += ps2esdi.o obj-$(CONFIG_BLK_DEV_XD) += xd.o diff --git a/drivers/block/brd.c b/drivers/block/brd.c new file mode 100644 index 0000000..50b659b --- /dev/null +++ b/drivers/block/brd.c @@ -0,0 +1,548 @@ +/* + * Ram backed block device driver. + * + * Copyright (C) 2007 Nick Piggin + * Copyright (C) 2007 Novell Inc. + * + * Parts derived from drivers/block/rd.c, and drivers/block/loop.c, copyright + * of their respective owners. + */ + +#include <linux/init.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/major.h> +#include <linux/blkdev.h> +#include <linux/bio.h> +#include <linux/highmem.h> +#include <linux/gfp.h> +#include <linux/radix-tree.h> +#include <linux/buffer_head.h> /* invalidate_bh_lrus() */ + +#include <asm/uaccess.h> + +#define SECTOR_SHIFT 9 +#define PAGE_SECTORS_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) +#define PAGE_SECTORS (1 << PAGE_SECTORS_SHIFT) + +/* + * Each block ramdisk device has a radix_tree brd_pages of pages that stores + * the pages containing the block device's contents. A brd page's ->index is + * its offset in PAGE_SIZE units. This is similar to, but in no way connected + * with, the kernel's pagecache or buffer cache (which sit above our block + * device). + */ +struct brd_device { + int brd_number; + int brd_refcnt; + loff_t brd_offset; + loff_t brd_sizelimit; + unsigned brd_blocksize; + + struct request_queue *brd_queue; + struct gendisk *brd_disk; + struct list_head brd_list; + + /* + * Backing store of pages and lock to protect it. This is the contents + * of the block device. + */ + spinlock_t brd_lock; + struct radix_tree_root brd_pages; +}; + +/* + * Look up and return a brd's page for a given sector. + */ +static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector) +{ + pgoff_t idx; + struct page *page; + + /* + * The page lifetime is protected by the fact that we have opened the + * device node -- brd pages will never be deleted under us, so we + * don't need any further locking or refcounting. + * + * This is strictly true for the radix-tree nodes as well (ie. we + * don't actually need the rcu_read_lock()), however that is not a + * documented feature of the radix-tree API so it is better to be + * safe here (we don't have total exclusion from radix tree updates + * here, only deletes). + */ + rcu_read_lock(); + idx = sector >> PAGE_SECTORS_SHIFT; /* sector to page index */ + page = radix_tree_lookup(&brd->brd_pages, idx); + rcu_read_unlock(); + + BUG_ON(page && page->index != idx); + + return page; +} + +/* + * Look up and return a brd's page for a given sector. + * If one does not exist, allocate an empty page, and insert that. Then + * return it. + */ +static struct page *brd_insert_page(struct brd_device *brd, sector_t sector) +{ + pgoff_t idx; + struct page *page; + + page = brd_lookup_page(brd, sector); + if (page) + return page; + + /* + * Must use NOIO because we don't want to recurse back into the + * block or filesystem layers from page reclaim. + */ + page = alloc_page(GFP_NOIO | __GFP_HIGHMEM | __GFP_ZERO); + if (!page) + return NULL; + + if (radix_tree_preload(GFP_NOIO)) { + __free_page(page); + return NULL; + } + + spin_lock(&brd->brd_lock); + idx = sector >> PAGE_SECTORS_SHIFT; + if (radix_tree_insert(&brd->brd_pages, idx, page)) { + __free_page(page); + page = radix_tree_lookup(&brd->brd_pages, idx); + BUG_ON(!page); + BUG_ON(page->index != idx); + } else + page->index = idx; + spin_unlock(&brd->brd_lock); + + radix_tree_preload_end(); + + return page; +} + +/* + * Free all backing store pages and radix tree. This must only be called when + * there are no other users of the device. + */ +#define FREE_BATCH 16 +static void brd_free_pages(struct brd_device *brd) +{ + unsigned long pos = 0; + struct page *pages[FREE_BATCH]; + int nr_pages; + + do { + int i; + + nr_pages = radix_tree_gang_lookup(&brd->brd_pages, + (void **)pages, pos, FREE_BATCH); + + for (i = 0; i < nr_pages; i++) { + void *ret; + + BUG_ON(pages[i]->index < pos); + pos = pages[i]->index; + ret = radix_tree_delete(&brd->brd_pages, pos); + BUG_ON(!ret || ret != pages[i]); + __free_page(pages[i]); + } + + pos++; + + /* + * This assumes radix_tree_gang_lookup always returns as + * many pages as possible. If the radix-tree code changes, + * so will this have to. + */ + } while (nr_pages == FREE_BATCH); +} + +/* + * copy_to_brd_setup must be called before copy_to_brd. It may sleep. + */ +static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n) +{ + unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; + size_t copy; + + copy = min_t(size_t, n, PAGE_SIZE - offset); + if (!brd_insert_page(brd, sector)) + return -ENOMEM; + if (copy < n) { + sector += copy >> SECTOR_SHIFT; + if (!brd_insert_page(brd, sector)) + return -ENOMEM; + } + return 0; +} + +/* + * Copy n bytes from src to the brd starting at sector. Does not sleep. + */ +static void copy_to_brd(struct brd_device *brd, const void *src, + sector_t sector, size_t n) +{ + struct page *page; + void *dst; + unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; + size_t copy; + + copy = min_t(size_t, n, PAGE_SIZE - offset); + page = brd_lookup_page(brd, sector); + BUG_ON(!page); + + dst = kmap_atomic(page, KM_USER1); + memcpy(dst + offset, src, copy); + kunmap_atomic(dst, KM_USER1); + + if (copy < n) { + src += copy; + sector += copy >> SECTOR_SHIFT; + copy = n - copy; + page = brd_lookup_page(brd, sector); + BUG_ON(!page); + + dst = kmap_atomic(page, KM_USER1); + memcpy(dst, src, copy); + kunmap_atomic(dst, KM_USER1); + } +} + +/* + * Copy n bytes to dst from the brd starting at sector. Does not sleep. + */ +static void copy_from_brd(void *dst, struct brd_device *brd, + sector_t sector, size_t n) +{ + struct page *page; + void *src; + unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT; + size_t copy; + + copy = min_t(size_t, n, PAGE_SIZE - offset); + page = brd_lookup_page(brd, sector); + if (page) { + src = kmap_atomic(page, KM_USER1); + memcpy(dst, src + offset, copy); + kunmap_atomic(src, KM_USER1); + } else + memset(dst, 0, copy); + + if (copy < n) { + dst += copy; + sector += copy >> SECTOR_SHIFT; + copy = n - copy; + page = brd_lookup_page(brd, sector); + if (page) { + src = kmap_atomic(page, KM_USER1); + memcpy(dst, src, copy); + kunmap_atomic(src, KM_USER1); + } else + memset(dst, 0, copy); + } +} + +/* + * Process a single bvec of a bio. + */ +static int brd_do_bvec(struct brd_device *brd, struct page *page, + unsigned int len, unsigned int off, int rw, + sector_t sector) +{ + void *mem; + int err = 0; + + if (rw != READ) { + err = copy_to_brd_setup(brd, sector, len); + if (err) + goto out; + } + + mem = kmap_atomic(page, KM_USER0); + if (rw == READ) { + copy_from_brd(mem + off, brd, sector, len); + flush_dcache_page(page); + } else + copy_to_brd(brd, mem + off, sector, len); + kunmap_atomic(mem, KM_USER0); + +out: + return err; +} + +static int brd_make_request(struct request_queue *q, struct bio *bio) +{ + struct block_device *bdev = bio->bi_bdev; + struct brd_device *brd = bdev->bd_disk->private_data; + int rw; + struct bio_vec *bvec; + sector_t sector; + int i; + int err = -EIO; + + sector = bio->bi_sector; + if (sector + (bio->bi_size >> SECTOR_SHIFT) > + get_capacity(bdev->bd_disk)) + goto out; + + rw = bio_rw(bio); + if (rw == READA) + rw = READ; + + bio_for_each_segment(bvec, bio, i) { + unsigned int len = bvec->bv_len; + err = brd_do_bvec(brd, bvec->bv_page, len, + bvec->bv_offset, rw, sector); + if (err) + break; + sector += len >> SECTOR_SHIFT; + } + +out: + bio_endio(bio, err); + + return 0; +} + +static int brd_ioctl(struct inode *inode, struct file *file, + unsigned int cmd, unsigned long arg) +{ + int error; + struct block_device *bdev = inode->i_bdev; + struct brd_device *brd = bdev->bd_disk->private_data; + + if (cmd != BLKFLSBUF) + return -ENOTTY; + + /* + * ram device BLKFLSBUF has special semantics, we want to actually + * release and destroy the ramdisk data. + */ + mutex_lock(&bdev->bd_mutex); + error = -EBUSY; + if (bdev->bd_openers <= 1) { + /* + * Invalidate the cache first, so it isn't written + * back to the device. + * + * Another thread might instantiate more buffercache here, + * but there is not much we can do to close that race. + */ + invalidate_bh_lrus(); + truncate_inode_pages(bdev->bd_inode->i_mapping, 0); + brd_free_pages(brd); + error = 0; + } + mutex_unlock(&bdev->bd_mutex); + + return error; +} + +static struct block_device_operations brd_fops = { + .owner = THIS_MODULE, + .ioctl = brd_ioctl, +}; + +/* + * And now the modules code and kernel interface. + */ +static int rd_nr; +int rd_size = CONFIG_BLK_DEV_RAM_SIZE; +module_param(rd_nr, int, 0); +MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); +module_param(rd_size, int, 0); +MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR); + +#ifndef MODULE +/* Legacy boot options - nonmodular */ +static int __init ramdisk_size(char *str) +{ + rd_size = simple_strtol(str, NULL, 0); + return 1; +} +static int __init ramdisk_size2(char *str) +{ + return ramdisk_size(str); +} +__setup("ramdisk=", ramdisk_size); +__setup("ramdisk_size=", ramdisk_size2); +#endif + +/* + * The device scheme is derived from loop.c. Keep them in synch where possible + * (should share code eventually). + */ +static LIST_HEAD(brd_devices); +static DEFINE_MUTEX(brd_devices_mutex); + +static struct brd_device *brd_alloc(int i) +{ + struct brd_device *brd; + struct gendisk *disk; + + brd = kzalloc(sizeof(*brd), GFP_KERNEL); + if (!brd) + goto out; + brd->brd_number = i; + spin_lock_init(&brd->brd_lock); + INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC); + + brd->brd_queue = blk_alloc_queue(GFP_KERNEL); + if (!brd->brd_queue) + goto out_free_dev; + blk_queue_make_request(brd->brd_queue, brd_make_request); + blk_queue_max_sectors(brd->brd_queue, 1024); + blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY); + + disk = brd->brd_disk = alloc_disk(1); + if (!disk) + goto out_free_queue; + disk->major = RAMDISK_MAJOR; + disk->first_minor = i; + disk->fops = &brd_fops; + disk->private_data = brd; + disk->queue = brd->brd_queue; + sprintf(disk->disk_name, "ram%d", i); + set_capacity(disk, rd_size * 2); + + return brd; + +out_free_queue: + blk_cleanup_queue(brd->brd_queue); +out_free_dev: + kfree(brd); +out: + return NULL; +} + +static void brd_free(struct brd_device *brd) +{ + put_disk(brd->brd_disk); + blk_cleanup_queue(brd->brd_queue); + brd_free_pages(brd); + kfree(brd); +} + +static struct brd_device *brd_init_one(int i) +{ + struct brd_device *brd; + + list_for_each_entry(brd, &brd_devices, brd_list) { + if (brd->brd_number == i) + goto out; + } + + brd = brd_alloc(i); + if (brd) { + add_disk(brd->brd_disk); + list_add_tail(&brd->brd_list, &brd_devices); + } +out: + return brd; +} + +static void brd_del_one(struct brd_device *brd) +{ + list_del(&brd->brd_list); + del_gendisk(brd->brd_disk); + brd_free(brd); +} + +static struct kobject *brd_probe(dev_t dev, int *part, void *data) +{ + struct brd_device *brd; + struct kobject *kobj; + + mutex_lock(&brd_devices_mutex); + brd = brd_init_one(dev & MINORMASK); + kobj = brd ? get_disk(brd->brd_disk) : ERR_PTR(-ENOMEM); + mutex_unlock(&brd_devices_mutex); + + *part = 0; + return kobj; +} + +static int __init brd_init(void) +{ + int i, nr; + unsigned long range; + struct brd_device *brd, *next; + + /* + * brd module now has a feature to instantiate underlying device + * structure on-demand, provided that there is an access dev node. + * However, this will not work well with user space tool that doesn't + * know about such "feature". In order to not break any existing + * tool, we do the following: + * + * (1) if rd_nr is specified, create that many upfront, and this + * also becomes a hard limit. + * (2) if rd_nr is not specified, create 1 rd device on module + * load, user can further extend brd device by create dev node + * themselves and have kernel automatically instantiate actual + * device on-demand. + */ + if (rd_nr > 1UL << MINORBITS) + return -EINVAL; + + if (rd_nr) { + nr = rd_nr; + range = rd_nr; + } else { + nr = CONFIG_BLK_DEV_RAM_COUNT; + range = 1UL << MINORBITS; + } + + if (register_blkdev(RAMDISK_MAJOR, "ramdisk")) + return -EIO; + + for (i = 0; i < nr; i++) { + brd = brd_alloc(i); + if (!brd) + goto out_free; + list_add_tail(&brd->brd_list, &brd_devices); + } + + /* point of no return */ + + list_for_each_entry(brd, &brd_devices, brd_list) + add_disk(brd->brd_disk); + + blk_register_region(MKDEV(RAMDISK_MAJOR, 0), range, + THIS_MODULE, brd_probe, NULL, NULL); + + printk(KERN_INFO "brd: module loaded\n"); + return 0; + +out_free: + list_for_each_entry_safe(brd, next, &brd_devices, brd_list) { + list_del(&brd->brd_list); + brd_free(brd); + } + + unregister_blkdev(RAMDISK_MAJOR, "brd"); + return -ENOMEM; +} + +static void __exit brd_exit(void) +{ + unsigned long range; + struct brd_device *brd, *next; + + range = rd_nr ? rd_nr : 1UL << MINORBITS; + + list_for_each_entry_safe(brd, next, &brd_devices, brd_list) + brd_del_one(brd); + + blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), range); + unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); +} + +module_init(brd_init); +module_exit(brd_exit); + diff --git a/drivers/block/rd.c b/drivers/block/rd.c deleted file mode 100644 index 06e23be..0000000 --- a/drivers/block/rd.c +++ /dev/null @@ -1,537 +0,0 @@ -/* - * 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 <linux/log2.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 || - !is_power_of_2(rd_blocksize)) { - 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"); |
