path: root/fs/btrfs/disk-io.c

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/crypto.h>
#include <linux/scatterlist.h>
#include <linux/swap.h>
#include <linux/radix-tree.h>
#include <linux/writeback.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "btrfs_inode.h"

struct dev_lookup {
	u64 block_start;
	u64 num_blocks;
	u64 device_id;
	struct block_device *bdev;
};

int btrfs_insert_dev_radix(struct btrfs_root *root,
			   struct block_device *bdev,
			   u64 device_id,
			   u64 block_start,
			   u64 num_blocks)
{
	struct dev_lookup *lookup;
	int ret;

	lookup = kmalloc(sizeof(*lookup), GFP_NOFS);
	if (!lookup)
		return -ENOMEM;
	lookup->block_start = block_start;
	lookup->num_blocks = num_blocks;
	lookup->bdev = bdev;
	lookup->device_id = device_id;

	ret = radix_tree_insert(&root->fs_info->dev_radix, block_start +
				num_blocks - 1, lookup);
	return ret;
}

u64 bh_blocknr(struct buffer_head *bh)
{
	int blkbits = bh->b_page->mapping->host->i_blkbits;
	u64 blocknr = bh->b_page->index << (PAGE_CACHE_SHIFT - blkbits);
	unsigned long offset;

	if (PageHighMem(bh->b_page))
		offset = (unsigned long)bh->b_data;
	else
		offset = bh->b_data - (char *)page_address(bh->b_page);
	blocknr += offset >> (PAGE_CACHE_SHIFT - blkbits);
	return blocknr;
}

static int check_tree_block(struct btrfs_root *root, struct buffer_head *buf)
{
	struct btrfs_node *node = btrfs_buffer_node(buf);
	if (bh_blocknr(buf) != btrfs_header_blocknr(&node->header)) {
		printk(KERN_CRIT "bh_blocknr(buf) is %Lu, header is %Lu\n",
		       bh_blocknr(buf), btrfs_header_blocknr(&node->header));
		BUG();
	}
	return 0;
}

struct buffer_head *btrfs_find_tree_block(struct btrfs_root *root, u64 blocknr)
{
	struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
	int blockbits = root->fs_info->sb->s_blocksize_bits;
	unsigned long index = blocknr >> (PAGE_CACHE_SHIFT - blockbits);
	struct page *page;
	struct buffer_head *bh;
	struct buffer_head *head;
	struct buffer_head *ret = NULL;


	page = find_lock_page(mapping, index);
	if (!page)
		return NULL;

	if (!page_has_buffers(page))
		goto out_unlock;

	head = page_buffers(page);
	bh = head;
	do {
		if (buffer_mapped(bh) && bh_blocknr(bh) == blocknr) {
			ret = bh;
			get_bh(bh);
			goto out_unlock;
		}
		bh = bh->b_this_page;
	} while (bh != head);
out_unlock:
	unlock_page(page);
	page_cache_release(page);
	return ret;
}

int btrfs_map_bh_to_logical(struct btrfs_root *root, struct buffer_head *bh,
			     u64 logical)
{
	struct dev_lookup *lookup[2];

	int ret;

	if (logical == 0) {
		bh->b_bdev = NULL;
		bh->b_blocknr = 0;
		set_buffer_mapped(bh);
		return 0;
	}
	root = root->fs_info->dev_root;
	ret = radix_tree_gang_lookup(&root->fs_info->dev_radix,
				     (void **)lookup,
				     (unsigned long)logical,
				     ARRAY_SIZE(lookup));
	if (ret == 0 || lookup[0]->block_start > logical ||
	    lookup[0]->block_start + lookup[0]->num_blocks <= logical) {
		ret = -ENOENT;
		goto out;
	}
	bh->b_bdev = lookup[0]->bdev;
	bh->b_blocknr = logical - lookup[0]->block_start;
	set_buffer_mapped(bh);
	ret = 0;
out:
	return ret;
}

struct buffer_head *btrfs_find_create_tree_block(struct btrfs_root *root,
						 u64 blocknr)
{
	struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
	int blockbits = root->fs_info->sb->s_blocksize_bits;
	unsigned long index = blocknr >> (PAGE_CACHE_SHIFT - blockbits);
	struct page *page;
	struct buffer_head *bh;
	struct buffer_head *head;
	struct buffer_head *ret = NULL;
	int err;
	u64 first_block = index << (PAGE_CACHE_SHIFT - blockbits);

	page = grab_cache_page(mapping, index);
	if (!page)
		return NULL;

	if (!page_has_buffers(page))
		create_empty_buffers(page, root->fs_info->sb->s_blocksize, 0);
	head = page_buffers(page);
	bh = head;
	do {
		if (!buffer_mapped(bh)) {