2 files changed, 99 insertions, 26 deletions

diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index 14862438faff..716c3fdeb257 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -97,8 +97,12 @@ static __inline__ bool ceph_msg_data_type_valid(enum ceph_msg_data_type type)
 
 struct ceph_msg_data_cursor {
         bool            last_piece;     /* now at last piece of data item */
-        struct page     *page;          /* current page in pagelist */
-        size_t          offset;         /* pagelist bytes consumed */
+        union {
+                struct {                                /* pagelist */
+                        struct page     *page;          /* page from list */
+                        size_t          offset;         /* bytes from list */
+                };
+        };
 };
 
 struct ceph_msg_data {
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index b978cf8b27ff..4cc27a136e35 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -742,21 +742,16 @@ static void iter_bio_next(struct bio **bio_iter, unsigned int *seg)
 #endif
 
 /*
- * Message data is handled (sent or received) in pieces, where each
- * piece resides on a single page.  The network layer might not
- * consume an entire piece at once.  A data item's cursor keeps
- * track of which piece is next to process and how much remains to
- * be processed in that piece.  It also tracks whether the current
- * piece is the last one in the data item.
+ * For a pagelist, a piece is whatever remains to be consumed in the
+ * first page in the list, or the front of the next page.
  */
-static void ceph_msg_data_cursor_init(struct ceph_msg_data *data)
+static void ceph_msg_data_pagelist_cursor_init(struct ceph_msg_data *data)
 {
         struct ceph_msg_data_cursor *cursor = &data->cursor;
         struct ceph_pagelist *pagelist;
         struct page *page;
 
-        if (data->type != CEPH_MSG_DATA_PAGELIST)
-                return;
+        BUG_ON(data->type != CEPH_MSG_DATA_PAGELIST);
 
         pagelist = data->pagelist;
         BUG_ON(!pagelist);
@@ -771,15 +766,9 @@ static void ceph_msg_data_cursor_init(struct ceph_msg_data *data)
         cursor->last_piece = pagelist->length <= PAGE_SIZE;
 }
 
-/*
- * Return the page containing the next piece to process for a given
- * data item, and supply the page offset and length of that piece.
- * Indicate whether this is the last piece in this data item.
- */
-static struct page *ceph_msg_data_next(struct ceph_msg_data *data,
+static struct page *ceph_msg_data_pagelist_next(struct ceph_msg_data *data,
                                                 size_t *page_offset,
-                                                size_t *length,
-                                                bool *last_piece)
+                                                size_t *length)
 {
         struct ceph_msg_data_cursor *cursor = &data->cursor;
         struct ceph_pagelist *pagelist;
@@ -793,8 +782,7 @@ static struct page *ceph_msg_data_next(struct ceph_msg_data *data,
         BUG_ON(!cursor->page);
         BUG_ON(cursor->offset >= pagelist->length);
 
-        *last_piece = cursor->last_piece;
-        if (*last_piece) {
+        if (cursor->last_piece) {
                 /* pagelist offset is always 0 */
                 piece_end = pagelist->length & ~PAGE_MASK;
                 if (!piece_end)
@@ -808,11 +796,8 @@ static struct page *ceph_msg_data_next(struct ceph_msg_data *data,
         return data->cursor.page;
 }
 
-/*
- * Returns true if the result moves the cursor on to the next piece
- * (the next page) of the pagelist.
- */
-static bool ceph_msg_data_advance(struct ceph_msg_data *data, size_t bytes)
+static bool ceph_msg_data_pagelist_advance(struct ceph_msg_data *data,
+                                                size_t bytes)
 {
         struct ceph_msg_data_cursor *cursor = &data->cursor;
         struct ceph_pagelist *pagelist;
@@ -844,6 +829,90 @@ static bool ceph_msg_data_advance(struct ceph_msg_data *data, size_t bytes)
         return true;
 }
 
+/*
+ * Message data is handled (sent or received) in pieces, where each
+ * piece resides on a single page.  The network layer might not
+ * consume an entire piece at once.  A data item's cursor keeps
+ * track of which piece is next to process and how much remains to
+ * be processed in that piece.  It also tracks whether the current
+ * piece is the last one in the data item.
+ */
+static void ceph_msg_data_cursor_init(struct ceph_msg_data *data)
+{
+        switch (data->type) {
+        case CEPH_MSG_DATA_PAGELIST:
+                ceph_msg_data_pagelist_cursor_init(data);
+                break;
+        case CEPH_MSG_DATA_NONE:
+        case CEPH_MSG_DATA_PAGES:
+#ifdef CONFIG_BLOCK
+        case CEPH_MSG_DATA_BIO:
+#endif /* CONFIG_BLOCK */
+        default:
+                /* BUG(); */
+                break;
+        }
+}
+
+/*
+ * Return the page containing the next piece to process for a given
+ * data item, and supply the page offset and length of that piece.
+ * Indicate whether this is the last piece in this data item.
+ */
+static struct page *ceph_msg_data_next(struct ceph_msg_data *data,
+                                        size_t *page_offset,
+                                        size_t *length,
+                                        bool *last_piece)
+{
+        struct page *page;
+
+        switch (data->type) {
+        case CEPH_MSG_DATA_PAGELIST:
+                page = ceph_msg_data_pagelist_next(data, page_offset, length);
+                break;
+        case CEPH_MSG_DATA_NONE:
+        case CEPH_MSG_DATA_PAGES:
+#ifdef CONFIG_BLOCK
+        case CEPH_MSG_DATA_BIO:
+#endif /* CONFIG_BLOCK */
+        default:
+                page = NULL;
+                break;
+        }
+        BUG_ON(!page);
+        BUG_ON(*page_offset + *length > PAGE_SIZE);
+        BUG_ON(!*length);
+        if (last_piece)
+                *last_piece = data->cursor.last_piece;
+
+        return page;
+}
+
+/*
+ * Returns true if the result moves the cursor on to the next piece
+ * of the data item.
+ */
+static bool ceph_msg_data_advance(struct ceph_msg_data *data, size_t bytes)
+{
+        bool new_piece;
+
+        switch (data->type) {
+        case CEPH_MSG_DATA_PAGELIST:
+                new_piece = ceph_msg_data_pagelist_advance(data, bytes);
+                break;
+        case CEPH_MSG_DATA_NONE:
+        case CEPH_MSG_DATA_PAGES:
+#ifdef CONFIG_BLOCK
+        case CEPH_MSG_DATA_BIO:
+#endif /* CONFIG_BLOCK */
+        default:
+                BUG();
+                break;
+        }
+
+        return new_piece;
+}
+
 static void prepare_message_data(struct ceph_msg *msg,
                                 struct ceph_msg_pos *msg_pos)
 {