libceph: drop last_piece flag from ceph_msg_data_cursor

ceph_msg_data_next is always passed a NULL pointer for this field. Some
of the "next" operations look at it in order to determine the length,
but we can just take the min of the data on the page or cursor->resid.

Signed-off-by: Jeff Layton <[e-mail]>
Reviewed-by: Xiubo Li <[e-mail]>
Reviewed-by: Ilya Dryomov <[e-mail]>
Signed-off-by: Ilya Dryomov <[e-mail]>

include/linux/ceph/messenger.h

···
 
 	struct ceph_msg_data	*data;		/* current data item */
 	size_t			resid;		/* bytes not yet consumed */
-	bool			last_piece;	/* current is last piece */
 	bool			need_crc;	/* crc update needed */
 	union {
 #ifdef CONFIG_BLOCK
···
 void ceph_msg_data_cursor_init(struct ceph_msg_data_cursor *cursor,
 			       struct ceph_msg *msg, size_t length);
 struct page *ceph_msg_data_next(struct ceph_msg_data_cursor *cursor,
-				size_t *page_offset, size_t *length,
-				bool *last_piece);
+				size_t *page_offset, size_t *length);
 void ceph_msg_data_advance(struct ceph_msg_data_cursor *cursor, size_t bytes);
 
 u32 ceph_crc32c_page(u32 crc, struct page *page, unsigned int page_offset,

net/ceph/messenger.c

···
 		it->iter.bi_size = cursor->resid;
 
 	BUG_ON(cursor->resid < bio_iter_len(it->bio, it->iter));
-	cursor->last_piece = cursor->resid == bio_iter_len(it->bio, it->iter);
 }
 
 static struct page *ceph_msg_data_bio_next(struct ceph_msg_data_cursor *cursor,
···
 	cursor->resid -= bytes;
 	bio_advance_iter(it->bio, &it->iter, bytes);
 
-	if (!cursor->resid) {
-		BUG_ON(!cursor->last_piece);
+	if (!cursor->resid)
 		return false;   /* no more data */
-	}
 
 	if (!bytes || (it->iter.bi_size && it->iter.bi_bvec_done &&
 		       page == bio_iter_page(it->bio, it->iter)))
···
 			it->iter.bi_size = cursor->resid;
 	}
 
-	BUG_ON(cursor->last_piece);
 	BUG_ON(cursor->resid < bio_iter_len(it->bio, it->iter));
-	cursor->last_piece = cursor->resid == bio_iter_len(it->bio, it->iter);
 	return true;
 }
 #endif /* CONFIG_BLOCK */
···
 	cursor->bvec_iter.bi_size = cursor->resid;
 
 	BUG_ON(cursor->resid < bvec_iter_len(bvecs, cursor->bvec_iter));
-	cursor->last_piece =
-	    cursor->resid == bvec_iter_len(bvecs, cursor->bvec_iter);
 }
 
 static struct page *ceph_msg_data_bvecs_next(struct ceph_msg_data_cursor *cursor,
···
 	cursor->resid -= bytes;
 	bvec_iter_advance(bvecs, &cursor->bvec_iter, bytes);
 
-	if (!cursor->resid) {
-		BUG_ON(!cursor->last_piece);
+	if (!cursor->resid)
 		return false;   /* no more data */
-	}
 
 	if (!bytes || (cursor->bvec_iter.bi_bvec_done &&
 		       page == bvec_iter_page(bvecs, cursor->bvec_iter)))
 		return false;	/* more bytes to process in this segment */
 
-	BUG_ON(cursor->last_piece);
 	BUG_ON(cursor->resid < bvec_iter_len(bvecs, cursor->bvec_iter));
-	cursor->last_piece =
-	    cursor->resid == bvec_iter_len(bvecs, cursor->bvec_iter);
 	return true;
 }
 
···
 	BUG_ON(page_count > (int)USHRT_MAX);
 	cursor->page_count = (unsigned short)page_count;
 	BUG_ON(length > SIZE_MAX - cursor->page_offset);
-	cursor->last_piece = cursor->page_offset + cursor->resid <= PAGE_SIZE;
 }
 
 static struct page *
···
 	BUG_ON(cursor->page_offset >= PAGE_SIZE);
 
 	*page_offset = cursor->page_offset;
-	if (cursor->last_piece)
-		*length = cursor->resid;
-	else
-		*length = PAGE_SIZE - *page_offset;
-
+	*length = min_t(size_t, cursor->resid, PAGE_SIZE - *page_offset);
 	return data->pages[cursor->page_index];
 }
 
···
 
 	BUG_ON(cursor->page_index >= cursor->page_count);
 	cursor->page_index++;
-	cursor->last_piece = cursor->resid <= PAGE_SIZE;
-
 	return true;
 }
 
···
 	cursor->resid = min(length, pagelist->length);
 	cursor->page = page;
 	cursor->offset = 0;
-	cursor->last_piece = cursor->resid <= PAGE_SIZE;
 }
 
 static struct page *
···
 
 	/* offset of first page in pagelist is always 0 */
 	*page_offset = cursor->offset & ~PAGE_MASK;
-	if (cursor->last_piece)
-		*length = cursor->resid;
-	else
-		*length = PAGE_SIZE - *page_offset;
-
+	*length = min_t(size_t, cursor->resid, PAGE_SIZE - *page_offset);
 	return cursor->page;
 }
 
···
 
 	BUG_ON(list_is_last(&cursor->page->lru, &pagelist->head));
 	cursor->page = list_next_entry(cursor->page, lru);
-	cursor->last_piece = cursor->resid <= PAGE_SIZE;
-
 	return true;
 }
 
···
  * Indicate whether this is the last piece in this data item.
  */
 struct page *ceph_msg_data_next(struct ceph_msg_data_cursor *cursor,
-				size_t *page_offset, size_t *length,
-				bool *last_piece)
+				size_t *page_offset, size_t *length)
 {
 	struct page *page;
 
···
 	BUG_ON(*page_offset + *length > PAGE_SIZE);
 	BUG_ON(!*length);
 	BUG_ON(*length > cursor->resid);
-	if (last_piece)
-		*last_piece = cursor->last_piece;
 
 	return page;
 }
···
 	cursor->total_resid -= bytes;
 
 	if (!cursor->resid && cursor->total_resid) {
-		WARN_ON(!cursor->last_piece);
 		cursor->data++;
 		__ceph_msg_data_cursor_init(cursor);
 		new_piece = true;

net/ceph/messenger_v1.c

···
 			continue;
 		}
 
-		page = ceph_msg_data_next(cursor, &page_offset, &length, NULL);
+		page = ceph_msg_data_next(cursor, &page_offset, &length);
 		if (length == cursor->total_resid)
 			more = MSG_MORE;
 		ret = ceph_tcp_sendpage(con->sock, page, page_offset, length,
···
 			continue;
 		}
 
-		page = ceph_msg_data_next(cursor, &page_offset, &length, NULL);
+		page = ceph_msg_data_next(cursor, &page_offset, &length);
 		ret = ceph_tcp_recvpage(con->sock, page, page_offset, length);
 		if (ret <= 0) {
 			if (do_datacrc)
···
 			continue;
 		}
 
-		page = ceph_msg_data_next(cursor, &off, &len, NULL);
+		page = ceph_msg_data_next(cursor, &off, &len);
 		ret = ceph_tcp_recvpage(con->sock, con->bounce_page, 0, len);
 		if (ret <= 0) {
 			con->in_data_crc = crc;

net/ceph/messenger_v2.c

···
 		ceph_msg_data_advance(cursor, 0);
 
 	/* get a piece of data, cursor isn't advanced */
-	page = ceph_msg_data_next(cursor, &off, &len, NULL);
+	page = ceph_msg_data_next(cursor, &off, &len);
 
 	bv->bv_page = page;
 	bv->bv_offset = off;