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 <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

include/linux/ceph/messenger.h

@@ -207,7 +207,6 @@ struct ceph_msg_data_cursor {
 
 	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
@@ -498,8 +497,7 @@ void ceph_con_discard_requeued(struct ceph_connection *con, u64 reconnect_seq);
 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

@@ -728,7 +728,6 @@ static void ceph_msg_data_bio_cursor_init(struct ceph_msg_data_cursor *cursor,
 		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,
@@ -754,10 +753,8 @@ static bool ceph_msg_data_bio_advance(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)))
@@ -770,9 +767,7 @@ static bool ceph_msg_data_bio_advance(struct ceph_msg_data_cursor *cursor,
 			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 */
@@ -788,8 +783,6 @@ static void ceph_msg_data_bvecs_cursor_init(struct ceph_msg_data_cursor *cursor,
 	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,
@@ -815,19 +808,14 @@ static bool ceph_msg_data_bvecs_advance(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;
 }
 
@@ -853,7 +841,6 @@ static void ceph_msg_data_pages_cursor_init(struct ceph_msg_data_cursor *cursor,
 	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 *
@@ -868,11 +855,7 @@ ceph_msg_data_pages_next(struct ceph_msg_data_cursor *cursor,
 	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];
 }
 
@@ -897,8 +880,6 @@ static bool ceph_msg_data_pages_advance(struct ceph_msg_data_cursor *cursor,
 
 	BUG_ON(cursor->page_index >= cursor->page_count);
 	cursor->page_index++;
-	cursor->last_piece = cursor->resid <= PAGE_SIZE;
-
 	return true;
 }
 
@@ -928,7 +909,6 @@ ceph_msg_data_pagelist_cursor_init(struct ceph_msg_data_cursor *cursor,
 	cursor->resid = min(length, pagelist->length);
 	cursor->page = page;
 	cursor->offset = 0;
-	cursor->last_piece = cursor->resid <= PAGE_SIZE;
 }
 
 static struct page *
@@ -948,11 +928,7 @@ ceph_msg_data_pagelist_next(struct ceph_msg_data_cursor *cursor,
 
 	/* 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;
 }
 
@@ -985,8 +961,6 @@ static bool ceph_msg_data_pagelist_advance(struct ceph_msg_data_cursor *cursor,
 
 	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;
 }
 
@@ -1044,8 +1018,7 @@ void ceph_msg_data_cursor_init(struct ceph_msg_data_cursor *cursor,
  * 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;
 
@@ -1074,8 +1047,6 @@ struct page *ceph_msg_data_next(struct ceph_msg_data_cursor *cursor,
 	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;
 }
@@ -1112,7 +1083,6 @@ void ceph_msg_data_advance(struct ceph_msg_data_cursor *cursor, size_t bytes)
 	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

@@ -495,7 +495,7 @@ static int write_partial_message_data(struct ceph_connection *con)
 			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,
@@ -1008,7 +1008,7 @@ static int read_partial_msg_data(struct ceph_connection *con)
 			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)
@@ -1050,7 +1050,7 @@ static int read_partial_msg_data_bounce(struct ceph_connection *con)
 			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

@@ -862,7 +862,7 @@ static void get_bvec_at(struct ceph_msg_data_cursor *cursor,
 		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;