Esempio n. 1
0
File: balloc.c Progetto: 7799/linux
/*
 * Modify inode page cache in such way:
 * have - blocks with b_blocknr equal to oldb...oldb+count-1
 * get - blocks with b_blocknr equal to newb...newb+count-1
 * also we suppose that oldb...oldb+count-1 blocks
 * situated at the end of file.
 *
 * We can come here from ufs_writepage or ufs_prepare_write,
 * locked_page is argument of these functions, so we already lock it.
 */
static void ufs_change_blocknr(struct inode *inode, sector_t beg,
			       unsigned int count, sector_t oldb,
			       sector_t newb, struct page *locked_page)
{
	const unsigned blks_per_page =
		1 << (PAGE_CACHE_SHIFT - inode->i_blkbits);
	const unsigned mask = blks_per_page - 1;
	struct address_space * const mapping = inode->i_mapping;
	pgoff_t index, cur_index, last_index;
	unsigned pos, j, lblock;
	sector_t end, i;
	struct page *page;
	struct buffer_head *head, *bh;

	UFSD("ENTER, ino %lu, count %u, oldb %llu, newb %llu\n",
	      inode->i_ino, count,
	     (unsigned long long)oldb, (unsigned long long)newb);

	BUG_ON(!locked_page);
	BUG_ON(!PageLocked(locked_page));

	cur_index = locked_page->index;
	end = count + beg;
	last_index = end >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
	for (i = beg; i < end; i = (i | mask) + 1) {
		index = i >> (PAGE_CACHE_SHIFT - inode->i_blkbits);

		if (likely(cur_index != index)) {
			page = ufs_get_locked_page(mapping, index);
			if (!page)/* it was truncated */
				continue;
			if (IS_ERR(page)) {/* or EIO */
				ufs_error(inode->i_sb, __func__,
					  "read of page %llu failed\n",
					  (unsigned long long)index);
				continue;
			}
		} else
			page = locked_page;

		head = page_buffers(page);
		bh = head;
		pos = i & mask;
		for (j = 0; j < pos; ++j)
			bh = bh->b_this_page;


		if (unlikely(index == last_index))
			lblock = end & mask;
		else
			lblock = blks_per_page;

		do {
			if (j >= lblock)
				break;
			pos = (i - beg) + j;

			if (!buffer_mapped(bh))
					map_bh(bh, inode->i_sb, oldb + pos);
			if (!buffer_uptodate(bh)) {
				ll_rw_block(READ, 1, &bh);
				wait_on_buffer(bh);
				if (!buffer_uptodate(bh)) {
					ufs_error(inode->i_sb, __func__,
						  "read of block failed\n");
					break;
				}
			}

			UFSD(" change from %llu to %llu, pos %u\n",
			     (unsigned long long)(pos + oldb),
			     (unsigned long long)(pos + newb), pos);

			bh->b_blocknr = newb + pos;
			unmap_underlying_metadata(bh->b_bdev,
						  bh->b_blocknr);
			mark_buffer_dirty(bh);
			++j;
			bh = bh->b_this_page;
		} while (bh != head);

		if (likely(cur_index != index))
			ufs_put_locked_page(page);
 	}
	UFSD("EXIT\n");
}
Esempio n. 2
0
/*
 * Modify inode page cache in such way:
 * have - blocks with b_blocknr equal to oldb...oldb+count-1
 * get - blocks with b_blocknr equal to newb...newb+count-1
 * also we suppose that oldb...oldb+count-1 blocks
 * situated at the end of file.
 *
 * We can come here from ufs_writepage or ufs_prepare_write,
 * locked_page is argument of these functions, so we already lock it.
 */
static void ufs_change_blocknr(struct inode *inode, unsigned int beg,
			       unsigned int count, unsigned int oldb,
			       unsigned int newb, struct page *locked_page)
{
	const unsigned mask = (1 << (PAGE_CACHE_SHIFT - inode->i_blkbits)) - 1;
	struct address_space * const mapping = inode->i_mapping;
	pgoff_t index, cur_index;
	unsigned end, pos, j;
	struct page *page;
	struct buffer_head *head, *bh;

	UFSD("ENTER, ino %lu, count %u, oldb %u, newb %u\n",
	      inode->i_ino, count, oldb, newb);

	BUG_ON(!locked_page);
	BUG_ON(!PageLocked(locked_page));

	cur_index = locked_page->index;

	for (end = count + beg; beg < end; beg = (beg | mask) + 1) {
		index = beg >> (PAGE_CACHE_SHIFT - inode->i_blkbits);

		if (likely(cur_index != index)) {
			page = ufs_get_locked_page(mapping, index);
			if (!page || IS_ERR(page)) /* it was truncated or EIO */
				continue;
		} else
			page = locked_page;

		head = page_buffers(page);
		bh = head;
		pos = beg & mask;
		for (j = 0; j < pos; ++j)
			bh = bh->b_this_page;
		j = 0;
		do {
			if (buffer_mapped(bh)) {
				pos = bh->b_blocknr - oldb;
				if (pos < count) {
					UFSD(" change from %llu to %llu\n",
					     (unsigned long long)pos + oldb,
					     (unsigned long long)pos + newb);
					bh->b_blocknr = newb + pos;
					unmap_underlying_metadata(bh->b_bdev,
								  bh->b_blocknr);
					mark_buffer_dirty(bh);
					++j;
				}
			}

			bh = bh->b_this_page;
		} while (bh != head);

		if (j)
			set_page_dirty(page);

		if (likely(cur_index != index))
			ufs_put_locked_page(page);
 	}
	UFSD("EXIT\n");
}