Re: [patch 10/19] Use page_cache_xxx in fs/buffer.c

[David Chinner <dgc@sgi.com>]

On Wed, Nov 28, 2007 at 05:11:02PM -0800, Christoph Lameter wrote:
> @@ -914,10 +914,11 @@ struct buffer_head *alloc_page_buffers(s
>  {
>  	struct buffer_head *bh, *head;
>  	long offset;
> +	unsigned int page_size = page_cache_size(page->mapping);
>  
>  try_again:
>  	head = NULL;
> -	offset = PAGE_SIZE;
> +	offset = page_size;
>  	while ((offset -= size) >= 0) {
>  		bh = alloc_buffer_head(GFP_NOFS);
>  		if (!bh)

We don't really need a temporary variable here....

>  	lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
>  	bh = head;
>  	nr = 0;
> @@ -2213,16 +2218,16 @@ int cont_expand_zero(struct file *file, 
>  	unsigned zerofrom, offset, len;
>  	int err = 0;
>  
> -	index = pos >> PAGE_CACHE_SHIFT;
> -	offset = pos & ~PAGE_CACHE_MASK;
> +	index = page_cache_index(mapping, pos);
> +	offset = page_cache_offset(mapping, pos);
>  
> -	while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
> -		zerofrom = curpos & ~PAGE_CACHE_MASK;
> +	while (index > (curidx = page_cache_index(mapping, (curpos = *bytes)))) {
> +		zerofrom = page_cache_offset(mapping, curpos);

That doesn't get any prettier. Perhaps:

	while (index > (curidx = page_cache_index(mapping, *bytes))) {
		curpos = *bytes;
		zerofrom = page_cache_offset(mapping, curpos);

> @@ -2356,20 +2362,22 @@ block_page_mkwrite(struct vm_area_struct
>  	unsigned long end;
>  	loff_t size;
>  	int ret = -EINVAL;
> +	struct address_space *mapping;
>  
>  	lock_page(page);
> +	mapping = page->mapping;
>  	size = i_size_read(inode);
> -	if ((page->mapping != inode->i_mapping) ||
> +	if ((mapping != inode->i_mapping) ||
>  	    (page_offset(page) > size)) {

Should check (page_cache_pos(mapping, page->index, 0) > size)

> @@ -2607,9 +2616,10 @@ EXPORT_SYMBOL(nobh_write_end);
>  int nobh_writepage(struct page *page, get_block_t *get_block,
>  			struct writeback_control *wbc)
>  {
> -	struct inode * const inode = page->mapping->host;
> +	struct address_space *mapping = page->mapping;
> +	struct inode * const inode = mapping->host;
>  	loff_t i_size = i_size_read(inode);
> -	const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
> +	const pgoff_t end_index = page_cache_offset(mapping, i_size);

	const pgoff_t end_index = page_cache_index(mapping, i_size);


Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group