Re: [PATCH v2 1/5] fs: Introduce i_blocks_per_page

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Tue, Aug 20, 2019 at 05:30:35PM -0700, Matthew Wilcox wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> 
> This helper is useful for both large pages in the page cache and for
> supporting block size larger than page size.  Convert some example
> users (we have a few different ways of writing this idiom).
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Seems pretty straightforward, modulo whatever's going on with the kbuild
robot complaint (is there something wrong, or is it just that obnoxious
header check thing?)

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/iomap/buffered-io.c  |  4 ++--
>  fs/jfs/jfs_metapage.c   |  2 +-
>  fs/xfs/xfs_aops.c       |  8 ++++----
>  include/linux/pagemap.h | 13 +++++++++++++
>  4 files changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index e25901ae3ff4..0e76a4b6d98a 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -24,7 +24,7 @@ iomap_page_create(struct inode *inode, struct page *page)
>  {
>  	struct iomap_page *iop = to_iomap_page(page);
>  
> -	if (iop || i_blocksize(inode) == PAGE_SIZE)
> +	if (iop || i_blocks_per_page(inode, page) <= 1)
>  		return iop;
>  
>  	iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
> @@ -128,7 +128,7 @@ iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
>  	bool uptodate = true;
>  
>  	if (iop) {
> -		for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
> +		for (i = 0; i < i_blocks_per_page(inode, page); i++) {
>  			if (i >= first && i <= last)
>  				set_bit(i, iop->uptodate);
>  			else if (!test_bit(i, iop->uptodate))
> diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c
> index a2f5338a5ea1..176580f54af9 100644
> --- a/fs/jfs/jfs_metapage.c
> +++ b/fs/jfs/jfs_metapage.c
> @@ -473,7 +473,7 @@ static int metapage_readpage(struct file *fp, struct page *page)
>  	struct inode *inode = page->mapping->host;
>  	struct bio *bio = NULL;
>  	int block_offset;
> -	int blocks_per_page = PAGE_SIZE >> inode->i_blkbits;
> +	int blocks_per_page = i_blocks_per_page(inode, page);
>  	sector_t page_start;	/* address of page in fs blocks */
>  	sector_t pblock;
>  	int xlen;
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index f16d5f196c6b..102cfd8a97d6 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -68,7 +68,7 @@ xfs_finish_page_writeback(
>  		mapping_set_error(inode->i_mapping, -EIO);
>  	}
>  
> -	ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
> +	ASSERT(iop || i_blocks_per_page(inode, bvec->bv_page) <= 1);
>  	ASSERT(!iop || atomic_read(&iop->write_count) > 0);
>  
>  	if (!iop || atomic_dec_and_test(&iop->write_count))
> @@ -839,7 +839,7 @@ xfs_aops_discard_page(
>  			page, ip->i_ino, offset);
>  
>  	error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
> -			PAGE_SIZE / i_blocksize(inode));
> +			i_blocks_per_page(inode, page));
>  	if (error && !XFS_FORCED_SHUTDOWN(mp))
>  		xfs_alert(mp, "page discard unable to remove delalloc mapping.");
>  out_invalidate:
> @@ -877,7 +877,7 @@ xfs_writepage_map(
>  	uint64_t		file_offset;	/* file offset of page */
>  	int			error = 0, count = 0, i;
>  
> -	ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
> +	ASSERT(iop || i_blocks_per_page(inode, page) <= 1);
>  	ASSERT(!iop || atomic_read(&iop->write_count) == 0);
>  
>  	/*
> @@ -886,7 +886,7 @@ xfs_writepage_map(
>  	 * one.
>  	 */
>  	for (i = 0, file_offset = page_offset(page);
> -	     i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
> +	     i < i_blocks_per_page(inode, page) && file_offset < end_offset;
>  	     i++, file_offset += len) {
>  		if (iop && !test_bit(i, iop->uptodate))
>  			continue;
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index cf837d313b96..2728f20fbc49 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -644,4 +644,17 @@ static inline unsigned long dir_pages(struct inode *inode)
>  			       PAGE_SHIFT;
>  }
>  
> +/**
> + * i_blocks_per_page - How many blocks fit in this page.
> + * @inode: The inode which contains the blocks.
> + * @page: The (potentially large) page.
> + *
> + * Context: Any context.
> + * Return: The number of filesystem blocks covered by this page.
> + */
> +static inline
> +unsigned int i_blocks_per_page(struct inode *inode, struct page *page)
> +{
> +	return page_size(page) >> inode->i_blkbits;
> +}
>  #endif /* _LINUX_PAGEMAP_H */
> -- 
> 2.23.0.rc1
>