cifs: Transition from ->readpages() to ->readahead()

	for (i = 0; i < rdata->nr_pages; i++) {

		struct page *page = rdata->pages[i];

		lru_cache_add(page);

		if (rdata->result == 0 ||

		    (rdata->result == -EAGAIN && got_bytes)) {

			flush_dcache_page(page);

			 * fill them until the writes are flushed.

			 */

			zero_user(page, 0, PAGE_SIZE);

			lru_cache_add(page);

			flush_dcache_page(page);

			SetPageUptodate(page);

			unlock_page(page);

			continue;

		} else {

			/* no need to hold page hostage */

			lru_cache_add(page);

			unlock_page(page);

			put_page(page);

			rdata->pages[i] = NULL;

	return readpages_fill_pages(server, rdata, iter, iter->count);

}

static int

readpages_get_pages(struct address_space *mapping, struct list_head *page_list,

		    unsigned int rsize, struct list_head *tmplist,

		    unsigned int *nr_pages, loff_t *offset, unsigned int *bytes)

{

	struct page *page, *tpage;

	unsigned int expected_index;

	int rc;

	gfp_t gfp = readahead_gfp_mask(mapping);

	INIT_LIST_HEAD(tmplist);

	page = lru_to_page(page_list);

	/*

	 * Lock the page and put it in the cache. Since no one else

	 * should have access to this page, we're safe to simply set

	 * PG_locked without checking it first.

	 */

	__SetPageLocked(page);

	rc = add_to_page_cache_locked(page, mapping,

				      page->index, gfp);

	/* give up if we can't stick it in the cache */

	if (rc) {

		__ClearPageLocked(page);

		return rc;

	}

	/* move first page to the tmplist */

	*offset = (loff_t)page->index << PAGE_SHIFT;

	*bytes = PAGE_SIZE;

	*nr_pages = 1;

	list_move_tail(&page->lru, tmplist);

	/* now try and add more pages onto the request */

	expected_index = page->index + 1;

	list_for_each_entry_safe_reverse(page, tpage, page_list, lru) {

		/* discontinuity ? */

		if (page->index != expected_index)

			break;

		/* would this page push the read over the rsize? */

		if (*bytes + PAGE_SIZE > rsize)

			break;

		__SetPageLocked(page);

		rc = add_to_page_cache_locked(page, mapping, page->index, gfp);

		if (rc) {

			__ClearPageLocked(page);

			break;

		}

		list_move_tail(&page->lru, tmplist);

		(*bytes) += PAGE_SIZE;

		expected_index++;

		(*nr_pages)++;

	}

	return rc;

}

static int cifs_readpages(struct file *file, struct address_space *mapping,

	struct list_head *page_list, unsigned num_pages)

static void cifs_readahead(struct readahead_control *ractl)

{

	int rc;

	int err = 0;

	struct list_head tmplist;

	struct cifsFileInfo *open_file = file->private_data;

	struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);

	struct cifsFileInfo *open_file = ractl->file->private_data;

	struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(ractl->file);

	struct TCP_Server_Info *server;

	pid_t pid;

	unsigned int xid;

	unsigned int xid, last_batch_size = 0;

	xid = get_xid();

	/*

	 * Reads as many pages as possible from fscache. Returns -ENOBUFS

	 * immediately if the cookie is negative

	 *

	 * After this point, every page in the list might have PG_fscache set,

	 * so we will need to clean that up off of every page we don't use.

	 */

	rc = cifs_readpages_from_fscache(mapping->host, mapping, page_list,

					 &num_pages);

	if (rc == 0) {

		free_xid(xid);

		return rc;

	}

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)

		pid = open_file->pid;

	server = cifs_pick_channel(tlink_tcon(open_file->tlink)->ses);

	cifs_dbg(FYI, "%s: file=%p mapping=%p num_pages=%u\n",

		 __func__, file, mapping, num_pages);

		 __func__, ractl->file, ractl->mapping, readahead_count(ractl));

	/*

	 * Start with the page at end of list and move it to private

	 * list. Do the same with any following pages until we hit

	 * the rsize limit, hit an index discontinuity, or run out of

	 * pages. Issue the async read and then start the loop again

	 * until the list is empty.

	 *

	 * Note that list order is important. The page_list is in

	 * the order of declining indexes. When we put the pages in

	 * the rdata->pages, then we want them in increasing order.

	 * Chop the readahead request up into rsize-sized read requests.

	 */

	while (!list_empty(page_list) && !err) {

		unsigned int i, nr_pages, bytes, rsize;

		loff_t offset;

		struct page *page, *tpage;

	while (readahead_count(ractl) - last_batch_size) {

		unsigned int i, nr_pages, got, rsize;

		struct page *page;

		struct cifs_readdata *rdata;

		struct cifs_credits credits_on_stack;

		struct cifs_credits *credits = &credits_on_stack;

		if (open_file->invalidHandle) {

			rc = cifs_reopen_file(open_file, true);

			if (rc) {

				if (rc == -EAGAIN)

					continue;

			else if (rc)

				break;

			}

		}

		rc = server->ops->wait_mtu_credits(server, cifs_sb->ctx->rsize,

						   &rsize, credits);

		if (rc)

			break;

		nr_pages = min_t(size_t, rsize / PAGE_SIZE, readahead_count(ractl));

		/*

		 * Give up immediately if rsize is too small to read an entire

		 * reach this point however since we set ra_pages to 0 when the

		 * rsize is smaller than a cache page.

		 */

		if (unlikely(rsize < PAGE_SIZE)) {

			add_credits_and_wake_if(server, credits, 0);

			free_xid(xid);

			return 0;

		}

		nr_pages = 0;

		err = readpages_get_pages(mapping, page_list, rsize, &tmplist,

					 &nr_pages, &offset, &bytes);

		if (!nr_pages) {

		if (unlikely(!nr_pages)) {

			add_credits_and_wake_if(server, credits, 0);

			break;

		}

		rdata = cifs_readdata_alloc(nr_pages, cifs_readv_complete);

		if (!rdata) {

			/* best to give up if we're out of mem */

			list_for_each_entry_safe(page, tpage, &tmplist, lru) {

				list_del(&page->lru);

				lru_cache_add(page);

				unlock_page(page);

				put_page(page);

			}

			rc = -ENOMEM;

			add_credits_and_wake_if(server, credits, 0);

			break;

		}

		got = __readahead_batch(ractl, rdata->pages, nr_pages);

		if (got != nr_pages) {

			pr_warn("__readahead_batch() returned %u/%u\n",

				got, nr_pages);

			nr_pages = got;

		}

		rdata->nr_pages = nr_pages;

		rdata->bytes	= readahead_batch_length(ractl);

		rdata->cfile	= cifsFileInfo_get(open_file);

		rdata->server	= server;

		rdata->mapping = mapping;

		rdata->offset = offset;

		rdata->bytes = bytes;

		rdata->mapping	= ractl->mapping;

		rdata->offset	= readahead_pos(ractl);

		rdata->pid	= pid;

		rdata->pagesz	= PAGE_SIZE;

		rdata->tailsz	= PAGE_SIZE;

		rdata->copy_into_pages = cifs_readpages_copy_into_pages;

		rdata->credits	= credits_on_stack;

		list_for_each_entry_safe(page, tpage, &tmplist, lru) {

			list_del(&page->lru);

			rdata->pages[rdata->nr_pages++] = page;

		}

		rc = adjust_credits(server, &rdata->credits, rdata->bytes);

		if (!rc) {

			if (rdata->cfile->invalidHandle)

				rc = -EAGAIN;

			add_credits_and_wake_if(server, &rdata->credits, 0);

			for (i = 0; i < rdata->nr_pages; i++) {

				page = rdata->pages[i];

				lru_cache_add(page);

				unlock_page(page);

				put_page(page);

			}

		}

		kref_put(&rdata->refcount, cifs_readdata_release);

		last_batch_size = nr_pages;

	}

	free_xid(xid);

	return rc;

}

/*

const struct address_space_operations cifs_addr_ops = {

	.readpage = cifs_readpage,

	.readpages = cifs_readpages,

	.readahead = cifs_readahead,

	.writepage = cifs_writepage,

	.writepages = cifs_writepages,

	.write_begin = cifs_write_begin,