* 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/bio.h>
#include <linux/buffer_head.h> /* for invalidate_bdev() */
#include <linux/backing-dev.h>
#include <linux/blkpg.h>
-#include <asm/uaccess.h>
+#include <linux/writeback.h>
-/* The RAM disk size is now a parameter */
-#define NUM_RAMDISKS 16 /* This cannot be overridden (yet) */
+#include <asm/uaccess.h>
/* Various static variables go here. Most are used only in the RAM disk code.
*/
-static struct gendisk *rd_disks[NUM_RAMDISKS];
-static struct block_device *rd_bdev[NUM_RAMDISKS];/* Protected device data */
-static struct request_queue *rd_queue[NUM_RAMDISKS];
+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
* behaviour. The default is still BLOCK_SIZE (needed by rd_load_image that
* supposes the filesystem in the image uses a BLOCK_SIZE blocksize).
*/
-int rd_blocksize = BLOCK_SIZE; /* blocksize of the RAM disks */
+static int rd_blocksize = CONFIG_BLK_DEV_RAM_BLOCKSIZE;
/*
* Copyright (C) 2000 Linus Torvalds.
* 2000 Transmeta Corp.
* aops copied from ramfs.
*/
-static int ramdisk_readpage(struct file *file, struct page *page)
-{
- if (!PageUptodate(page)) {
- void *kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr, 0, PAGE_CACHE_SIZE);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- SetPageUptodate(page);
+/*
+ * 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)) {
- void *kaddr = kmap_atomic(page, KM_USER0);
-
- memset(kaddr, 0, PAGE_CACHE_SIZE);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- SetPageUptodate(page);
- }
- SetPageDirty(page);
+ 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 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;
}
-static struct address_space_operations ramdisk_aops = {
- .readpage = ramdisk_readpage,
- .prepare_write = ramdisk_prepare_write,
- .commit_write = ramdisk_commit_write,
+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,
};
static int rd_blkdev_pagecache_IO(int rw, struct bio_vec *vec, sector_t sector,
struct address_space *mapping)
{
- unsigned long index = sector >> (PAGE_CACHE_SHIFT - 9);
+ 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;
do {
int count;
- struct page * page;
- char * src, * dst;
- int unlock = 0;
+ struct page *page;
+ char *src;
+ char *dst;
count = PAGE_CACHE_SIZE - offset;
if (count > size)
count = size;
size -= count;
- page = find_get_page(mapping, index);
+ page = grab_cache_page(mapping, index);
if (!page) {
- page = grab_cache_page(mapping, index);
err = -ENOMEM;
- if (!page)
- goto out;
- err = 0;
-
- if (!PageUptodate(page)) {
- void *kaddr = kmap_atomic(page, KM_USER0);
-
- memset(kaddr, 0, PAGE_CACHE_SIZE);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- SetPageUptodate(page);
- }
-
- unlock = 1;
+ goto out;
}
+ if (!PageUptodate(page))
+ make_page_uptodate(page);
+
index++;
if (rw == READ) {
- src = kmap(page) + offset;
- dst = kmap(vec->bv_page) + vec_offset;
+ src = kmap_atomic(page, KM_USER0) + offset;
+ dst = kmap_atomic(vec->bv_page, KM_USER1) + vec_offset;
} else {
- dst = kmap(page) + offset;
- src = kmap(vec->bv_page) + vec_offset;
+ 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(page);
- kunmap(vec->bv_page);
+ kunmap_atomic(src, KM_USER0);
+ kunmap_atomic(dst, KM_USER1);
- if (rw == READ) {
+ if (rw == READ)
flush_dcache_page(vec->bv_page);
- } else {
- SetPageDirty(page);
- }
- if (unlock)
- unlock_page(page);
- __free_page(page);
+ else
+ set_page_dirty(page);
+ unlock_page(page);
+ put_page(page);
} while (size);
out:
struct block_device *bdev = inode->i_bdev;
if (cmd != BLKFLSBUF)
- return -EINVAL;
+ return -ENOTTY;
/*
* special: we want to release the ramdisk memory, it's not like with
* cache
*/
error = -EBUSY;
- down(&bdev->bd_sem);
+ mutex_lock(&bdev->bd_mutex);
if (bdev->bd_openers <= 2) {
truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
error = 0;
}
- up(&bdev->bd_sem);
+ 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 */
- .memory_backed = 1, /* Does not contribute to dirty memory */
- .unplug_io_fn = default_unplug_io_fn,
+ .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);
- /*
- * Immunize device against invalidate_buffers() and prune_icache().
- */
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++;
- bdev->bd_block_size = rd_blocksize;
- inode->i_size = get_capacity(rd_disks[unit])<<9;
- inode->i_mapping->a_ops = &ramdisk_aops;
- inode->i_mapping->backing_dev_info = &rd_backing_dev_info;
+ 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;
{
int i;
- for (i = 0; i < NUM_RAMDISKS; i++) {
+ for (i = 0; i < CONFIG_BLK_DEV_RAM_COUNT; i++) {
struct block_device *bdev = rd_bdev[i];
rd_bdev[i] = NULL;
if (bdev) {
put_disk(rd_disks[i]);
blk_cleanup_queue(rd_queue[i]);
}
- devfs_remove("rd");
unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
}
rd_blocksize = BLOCK_SIZE;
}
- for (i = 0; i < NUM_RAMDISKS; i++) {
+ 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")) {
goto out;
}
- devfs_mk_dir("rd");
-
- for (i = 0; i < NUM_RAMDISKS; i++) {
+ 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->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",
- NUM_RAMDISKS, rd_size, rd_blocksize);
+ 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]);
#endif
/* options - modular */
-MODULE_PARM (rd_size, "1i");
+module_param(rd_size, int, 0);
MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");
-MODULE_PARM (rd_blocksize, "i");
+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");
git://git.onelab.eu / linux-2.6.git / blobdiff