Message-ID: <20070830092038.GD22586@dnb.sw.ru>
Date:	Thu, 30 Aug 2007 13:20:38 +0400
From:	Dmitry Monakhov <dmonakhov@...ru>
To:	clameter@....com
Cc:	torvalds@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, Christoph Hellwig <hch@....de>,
	Mel Gorman <mel@...net.ie>,
	William Lee Irwin III <wli@...omorphy.com>,
	David Chinner <dgc@....com>,
	Jens Axboe <jens.axboe@...cle.com>,
	Badari Pulavarty <pbadari@...il.com>,
	Maxim Levitsky <maximlevitsky@...il.com>,
	Fengguang Wu <fengguang.wu@...il.com>,
	swin wang <wangswin@...il.com>, totty.lu@...il.com,
	"H. Peter Anvin" <hpa@...or.com>, joern@...ybastard.org,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [11/36] Use page_cache_xxx in fs/buffer.c

On 12:06 Tue 28 Aug     , clameter@....com wrote:
> Use page_cache_xxx in fs/buffer.c.
submit_bh wasn't changed this means what bio pages may have huge size
without respect to queue reqsrictions (q->max_hw_segments, and etc)
At least driver/md/raid0 will be broken by you'r patch.
> 
> We have a special situation in set_bh_page() since reiserfs calls that
> function before setting up the mapping. So retrieve the page size
> from the page struct rather than the mapping.
> 
> Signed-off-by: Christoph Lameter <clameter@....com>
> ---
>  fs/buffer.c |  110 +++++++++++++++++++++++++++++++++---------------------------
>  1 file changed, 62 insertions(+), 48 deletions(-)
> 
> Index: linux-2.6/fs/buffer.c
> ===================================================================
> --- linux-2.6.orig/fs/buffer.c	2007-08-28 11:37:13.000000000 -0700
> +++ linux-2.6/fs/buffer.c	2007-08-28 11:37:58.000000000 -0700
> @@ -257,7 +257,7 @@ __find_get_block_slow(struct block_devic
>  	struct page *page;
>  	int all_mapped = 1;
>  
> -	index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
> +	index = block >> (page_cache_shift(bd_mapping) - bd_inode->i_blkbits);
>  	page = find_get_page(bd_mapping, index);
>  	if (!page)
>  		goto out;
> @@ -697,7 +697,7 @@ static int __set_page_dirty(struct page 
>  
>  		if (mapping_cap_account_dirty(mapping)) {
>  			__inc_zone_page_state(page, NR_FILE_DIRTY);
> -			task_io_account_write(PAGE_CACHE_SIZE);
> +			task_io_account_write(page_cache_size(mapping));
>  		}
>  		radix_tree_tag_set(&mapping->page_tree,
>  				page_index(page), PAGECACHE_TAG_DIRTY);
> @@ -891,10 +891,11 @@ 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)
> @@ -1426,7 +1427,7 @@ void set_bh_page(struct buffer_head *bh,
>  		struct page *page, unsigned long offset)
>  {
>  	bh->b_page = page;
> -	BUG_ON(offset >= PAGE_SIZE);
> +	BUG_ON(offset >= compound_size(page));
>  	if (PageHighMem(page))
>  		/*
>  		 * This catches illegal uses and preserves the offset:
> @@ -1605,6 +1606,7 @@ static int __block_write_full_page(struc
>  	struct buffer_head *bh, *head;
>  	const unsigned blocksize = 1 << inode->i_blkbits;
>  	int nr_underway = 0;
> +	struct address_space *mapping = inode->i_mapping;
>  
>  	BUG_ON(!PageLocked(page));
>  
> @@ -1625,7 +1627,8 @@ static int __block_write_full_page(struc
>  	 * handle that here by just cleaning them.
>  	 */
>  
> -	block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
> +	block = (sector_t)page->index <<
> +		(page_cache_shift(mapping) - inode->i_blkbits);
>  	head = page_buffers(page);
>  	bh = head;
>  
> @@ -1742,7 +1745,7 @@ recover:
>  	} while ((bh = bh->b_this_page) != head);
>  	SetPageError(page);
>  	BUG_ON(PageWriteback(page));
> -	mapping_set_error(page->mapping, err);
> +	mapping_set_error(mapping, err);
>  	set_page_writeback(page);
>  	do {
>  		struct buffer_head *next = bh->b_this_page;
> @@ -1767,8 +1770,8 @@ static int __block_prepare_write(struct 
>  	struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
>  
>  	BUG_ON(!PageLocked(page));
> -	BUG_ON(from > PAGE_CACHE_SIZE);
> -	BUG_ON(to > PAGE_CACHE_SIZE);
> +	BUG_ON(from > page_cache_size(inode->i_mapping));
> +	BUG_ON(to > page_cache_size(inode->i_mapping));
>  	BUG_ON(from > to);
>  
>  	blocksize = 1 << inode->i_blkbits;
> @@ -1777,7 +1780,8 @@ static int __block_prepare_write(struct 
>  	head = page_buffers(page);
>  
>  	bbits = inode->i_blkbits;
> -	block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
> +	block = (sector_t)page->index <<
> +		(page_cache_shift(inode->i_mapping) - bbits);
>  
>  	for(bh = head, block_start = 0; bh != head || !block_start;
>  	    block++, block_start=block_end, bh = bh->b_this_page) {
> @@ -1921,7 +1925,8 @@ int block_read_full_page(struct page *pa
>  		create_empty_buffers(page, blocksize, 0);
>  	head = page_buffers(page);
>  
> -	iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
> +	iblock = (sector_t)page->index <<
> +		(page_cache_shift(page->mapping) - inode->i_blkbits);
>  	lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
>  	bh = head;
>  	nr = 0;
> @@ -2045,7 +2050,7 @@ int generic_cont_expand(struct inode *in
>  	pgoff_t index;
>  	unsigned int offset;
>  
> -	offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */
> +	offset = page_cache_offset(inode->i_mapping, size); /* Within page */
>  
>  	/* ugh.  in prepare/commit_write, if from==to==start of block, we
>  	** skip the prepare.  make sure we never send an offset for the start
> @@ -2055,7 +2060,7 @@ int generic_cont_expand(struct inode *in
>  		/* caller must handle this extra byte. */
>  		offset++;
>  	}
> -	index = size >> PAGE_CACHE_SHIFT;
> +	index = page_cache_index(inode->i_mapping, size);
>  
>  	return __generic_cont_expand(inode, size, index, offset);
>  }
> @@ -2063,8 +2068,8 @@ int generic_cont_expand(struct inode *in
>  int generic_cont_expand_simple(struct inode *inode, loff_t size)
>  {
>  	loff_t pos = size - 1;
> -	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
> -	unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
> +	pgoff_t index = page_cache_index(inode->i_mapping, pos);
> +	unsigned int offset = page_cache_offset(inode->i_mapping, pos) + 1;
>  
>  	/* prepare/commit_write can handle even if from==to==start of block. */
>  	return __generic_cont_expand(inode, size, index, offset);
> @@ -2086,28 +2091,28 @@ int cont_prepare_write(struct page *page
>  	unsigned zerofrom;
>  	unsigned blocksize = 1 << inode->i_blkbits;
>  
> -	while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) {
> +	while (page->index > (pgpos = page_cache_index(mapping, *bytes))) {
>  		status = -ENOMEM;
>  		new_page = grab_cache_page(mapping, pgpos);
>  		if (!new_page)
>  			goto out;
>  		/* we might sleep */
> -		if (*bytes>>PAGE_CACHE_SHIFT != pgpos) {
> +		if (page_cache_index(mapping, *bytes) != pgpos) {
>  			unlock_page(new_page);
>  			page_cache_release(new_page);
>  			continue;
>  		}
> -		zerofrom = *bytes & ~PAGE_CACHE_MASK;
> +		zerofrom = page_cache_offset(mapping, *bytes);
>  		if (zerofrom & (blocksize-1)) {
>  			*bytes |= (blocksize-1);
>  			(*bytes)++;
>  		}
>  		status = __block_prepare_write(inode, new_page, zerofrom,
> -						PAGE_CACHE_SIZE, get_block);
> +					page_cache_size(mapping), get_block);
>  		if (status)
>  			goto out_unmap;
> -		zero_user_segment(new_page, zerofrom, PAGE_CACHE_SIZE);
> -		generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
> +		zero_user_segment(new_page, zerofrom, page_cache_size(mapping));
> +		generic_commit_write(NULL, new_page, zerofrom, page_cache_size(mapping));
>  		unlock_page(new_page);
>  		page_cache_release(new_page);
>  	}
> @@ -2117,7 +2122,7 @@ int cont_prepare_write(struct page *page
>  		zerofrom = offset;
>  	} else {
>  		/* page covers the boundary, find the boundary offset */
> -		zerofrom = *bytes & ~PAGE_CACHE_MASK;
> +		zerofrom = page_cache_offset(mapping, *bytes);
>  
>  		/* if we will expand the thing last block will be filled */
>  		if (to > zerofrom && (zerofrom & (blocksize-1))) {
> @@ -2169,8 +2174,9 @@ int block_commit_write(struct page *page
>  int generic_commit_write(struct file *file, struct page *page,
>  		unsigned from, unsigned to)
>  {
> -	struct inode *inode = page->mapping->host;
> -	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
> +	struct address_space *mapping = page->mapping;
> +	struct inode *inode = mapping->host;
> +	loff_t pos = page_cache_pos(mapping, page->index, to);
>  	__block_commit_write(inode,page,from,to);
>  	/*
>  	 * No need to use i_size_read() here, the i_size
> @@ -2206,20 +2212,22 @@ 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)) {
>  		/* page got truncated out from underneath us */
>  		goto out_unlock;
>  	}
>  
>  	/* page is wholly or partially inside EOF */
> -	if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
> -		end = size & ~PAGE_CACHE_MASK;
> +	if (page_cache_pos(mapping, page->index + 1, 0) > size)
> +		end = page_cache_offset(mapping, size);
>  	else
> -		end = PAGE_CACHE_SIZE;
> +		end = page_cache_size(mapping);
>  
>  	ret = block_prepare_write(page, 0, end, get_block);
>  	if (!ret)
> @@ -2258,6 +2266,7 @@ static void end_buffer_read_nobh(struct 
>  int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
>  			get_block_t *get_block)
>  {
> +	struct address_space *mapping = page->mapping;
>  	struct inode *inode = page->mapping->host;
>  	const unsigned blkbits = inode->i_blkbits;
>  	const unsigned blocksize = 1 << blkbits;
> @@ -2265,6 +2274,7 @@ int nobh_prepare_write(struct page *page
>  	struct buffer_head *read_bh[MAX_BUF_PER_PAGE];
>  	unsigned block_in_page;
>  	unsigned block_start;
> +	unsigned page_size = page_cache_size(mapping);
>  	sector_t block_in_file;
>  	int nr_reads = 0;
>  	int i;
> @@ -2274,7 +2284,8 @@ int nobh_prepare_write(struct page *page
>  	if (PageMappedToDisk(page))
>  		return 0;
>  
> -	block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
> +	block_in_file = (sector_t)page->index <<
> +			(page_cache_shift(mapping) - blkbits);
>  	map_bh.b_page = page;
>  
>  	/*
> @@ -2283,7 +2294,7 @@ int nobh_prepare_write(struct page *page
>  	 * page is fully mapped-to-disk.
>  	 */
>  	for (block_start = 0, block_in_page = 0;
> -		  block_start < PAGE_CACHE_SIZE;
> +		  block_start < page_size;
>  		  block_in_page++, block_start += blocksize) {
>  		unsigned block_end = block_start + blocksize;
>  		int create;
> @@ -2372,7 +2383,7 @@ failed:
>  	 * Error recovery is pretty slack.  Clear the page and mark it dirty
>  	 * so we'll later zero out any blocks which _were_ allocated.
>  	 */
> -	zero_user(page, 0, PAGE_CACHE_SIZE);
> +	zero_user(page, 0, page_size);
>  	SetPageUptodate(page);
>  	set_page_dirty(page);
>  	return ret;
> @@ -2386,8 +2397,9 @@ EXPORT_SYMBOL(nobh_prepare_write);
>  int nobh_commit_write(struct file *file, struct page *page,
>  		unsigned from, unsigned to)
>  {
> -	struct inode *inode = page->mapping->host;
> -	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
> +	struct address_space *mapping = page->mapping;
> +	struct inode *inode = mapping->host;
> +	loff_t pos = page_cache_pos(mapping, page->index, to);
>  
>  	SetPageUptodate(page);
>  	set_page_dirty(page);
> @@ -2407,9 +2419,10 @@ EXPORT_SYMBOL(nobh_commit_write);
>  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);
>  	unsigned offset;
>  	int ret;
>  
> @@ -2418,7 +2431,7 @@ int nobh_writepage(struct page *page, ge
>  		goto out;
>  
>  	/* Is the page fully outside i_size? (truncate in progress) */
> -	offset = i_size & (PAGE_CACHE_SIZE-1);
> +	offset = page_cache_offset(mapping, i_size);
>  	if (page->index >= end_index+1 || !offset) {
>  		/*
>  		 * The page may have dirty, unmapped buffers.  For example,
> @@ -2441,7 +2454,7 @@ int nobh_writepage(struct page *page, ge
>  	 * the  page size, the remaining memory is zeroed when mapped, and
>  	 * writes to that region are not written out to the file."
>  	 */
> -	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
> +	zero_user_segment(page, offset, page_cache_size(mapping));
>  out:
>  	ret = mpage_writepage(page, get_block, wbc);
>  	if (ret == -EAGAIN)
> @@ -2457,8 +2470,8 @@ int nobh_truncate_page(struct address_sp
>  {
>  	struct inode *inode = mapping->host;
>  	unsigned blocksize = 1 << inode->i_blkbits;
> -	pgoff_t index = from >> PAGE_CACHE_SHIFT;
> -	unsigned offset = from & (PAGE_CACHE_SIZE-1);
> +	pgoff_t index = page_cache_index(mapping, from);
> +	unsigned offset = page_cache_offset(mapping, from);
>  	unsigned to;
>  	struct page *page;
>  	const struct address_space_operations *a_ops = mapping->a_ops;
> @@ -2475,7 +2488,7 @@ int nobh_truncate_page(struct address_sp
>  	to = (offset + blocksize) & ~(blocksize - 1);
>  	ret = a_ops->prepare_write(NULL, page, offset, to);
>  	if (ret == 0) {
> -		zero_user_segment(page, offset, PAGE_CACHE_SIZE);
> +		zero_user_segment(page, offset, page_cache_size(mapping));
>  		/*
>  		 * It would be more correct to call aops->commit_write()
>  		 * here, but this is more efficient.
> @@ -2493,8 +2506,8 @@ EXPORT_SYMBOL(nobh_truncate_page);
>  int block_truncate_page(struct address_space *mapping,
>  			loff_t from, get_block_t *get_block)
>  {
> -	pgoff_t index = from >> PAGE_CACHE_SHIFT;
> -	unsigned offset = from & (PAGE_CACHE_SIZE-1);
> +	pgoff_t index = page_cache_index(mapping, from);
> +	unsigned offset = page_cache_offset(mapping, from);
>  	unsigned blocksize;
>  	sector_t iblock;
>  	unsigned length, pos;
> @@ -2511,8 +2524,8 @@ int block_truncate_page(struct address_s
>  		return 0;
>  
>  	length = blocksize - length;
> -	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
> -	
> +	iblock = (sector_t)index <<
> +			(page_cache_shift(mapping) - inode->i_blkbits);
>  	page = grab_cache_page(mapping, index);
>  	err = -ENOMEM;
>  	if (!page)
> @@ -2571,9 +2584,10 @@ out:
>  int block_write_full_page(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_index(mapping, i_size);
>  	unsigned offset;
>  
>  	/* Is the page fully inside i_size? */
> @@ -2581,7 +2595,7 @@ int block_write_full_page(struct page *p
>  		return __block_write_full_page(inode, page, get_block, wbc);
>  
>  	/* Is the page fully outside i_size? (truncate in progress) */
> -	offset = i_size & (PAGE_CACHE_SIZE-1);
> +	offset = page_cache_offset(mapping, i_size);
>  	if (page->index >= end_index+1 || !offset) {
>  		/*
>  		 * The page may have dirty, unmapped buffers.  For example,
> @@ -2600,7 +2614,7 @@ int block_write_full_page(struct page *p
>  	 * the  page size, the remaining memory is zeroed when mapped, and
>  	 * writes to that region are not written out to the file."
>  	 */
> -	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
> +	zero_user_segment(page, offset, page_cache_size(mapping));
>  	return __block_write_full_page(inode, page, get_block, wbc);
>  }
>  
> @@ -2854,7 +2868,7 @@ int try_to_free_buffers(struct page *pag
>  	 * dirty bit from being lost.
>  	 */
>  	if (ret)
> -		cancel_dirty_page(page, PAGE_CACHE_SIZE);
> +		cancel_dirty_page(page, page_cache_size(mapping));
>  	spin_unlock(&mapping->private_lock);
>  out:
>  	if (buffers_to_free) {
> 
> -- 
> -
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