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Commit 49d0b21b authored by Jens Axboe's avatar Jens Axboe
Browse files

[PATCH] splice: optimize the splice buffer mapping 



We don't really need to lock down the pages, just make sure they
are uptodate.

Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent 16c523dd

fs/splice.c

+30 −10
Original line number Diff line number Diff line
@@ -84,26 +84,43 @@ static void *page_cache_pipe_buf_map(struct file *file, 
				     struct pipe_buffer *buf)

{

	struct page *page = buf->page;

	int err;



	if (!PageUptodate(page)) {

		lock_page(page);



		/*

		 * Page got truncated/unhashed. This will cause a 0-byte

		 * splice, if this is the first page

		 */

		if (!page->mapping) {

			err = -ENODATA;

			goto error;

		}



		/*

		 * uh oh, read-error from disk

		 */

		if (!PageUptodate(page)) {

		unlock_page(page);

		return ERR_PTR(-EIO);

			err = -EIO;

			goto error;

		}



	if (!page->mapping) {

		/*

		 * page is ok afterall, fall through to mapping

		 */

		unlock_page(page);

		return ERR_PTR(-ENODATA);

	}



	return kmap(buf->page);

	return kmap(page);

error:

	unlock_page(page);

	return ERR_PTR(err);

}



static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,

				      struct pipe_buffer *buf)

{

	unlock_page(buf->page);

	kunmap(buf->page);

}
@@ -379,7 +396,7 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, 
	int ret;



	/*

	 * after this, page will be locked and unmapped

	 * make sure the data in this buffer is uptodate

	 */

	src = buf->ops->map(file, info, buf);

	if (IS_ERR(src))
@@ -399,6 +416,9 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, 
		if (buf->ops->steal(info, buf))

			goto find_page;



		/*

		 * this will also set the page locked

		 */

		page = buf->page;

		if (add_to_page_cache(page, mapping, index, gfp_mask))

			goto find_page;