libceph: have cursor point to data

Rather than having a ceph message data item point to the cursor it's
associated with, have the cursor point to a data item.  This will
allow a message cursor to be used for more than one data item.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 55 insertions, 58 deletions

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 4626da34a5c3..3aa0f30c3c5e 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -722,10 +722,10 @@ static void con_out_kvec_add(struct ceph_connection *con,
  * entry in the current bio iovec, or the first entry in the next
  * bio in the list.
  */
-static void ceph_msg_data_bio_cursor_init(struct ceph_msg_data *data,
+static void ceph_msg_data_bio_cursor_init(struct ceph_msg_data_cursor *cursor,
                                         size_t length)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
+        struct ceph_msg_data *data = cursor->data;
         struct bio *bio;
 
         BUG_ON(data->type != CEPH_MSG_DATA_BIO);
@@ -741,11 +741,11 @@ static void ceph_msg_data_bio_cursor_init(struct ceph_msg_data *data,
         cursor->last_piece = length <= bio->bi_io_vec[0].bv_len;
 }
 
-static struct page *ceph_msg_data_bio_next(struct ceph_msg_data *data,
+static struct page *ceph_msg_data_bio_next(struct ceph_msg_data_cursor *cursor,
                                                 size_t *page_offset,
                                                 size_t *length)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
+        struct ceph_msg_data *data = cursor->data;
         struct bio *bio;
         struct bio_vec *bio_vec;
         unsigned int index;
@@ -772,14 +772,14 @@ static struct page *ceph_msg_data_bio_next(struct ceph_msg_data *data,
         return bio_vec->bv_page;
 }
 
-static bool ceph_msg_data_bio_advance(struct ceph_msg_data *data, size_t bytes)
+static bool ceph_msg_data_bio_advance(struct ceph_msg_data_cursor *cursor,
+                                        size_t bytes)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
         struct bio *bio;
         struct bio_vec *bio_vec;
         unsigned int index;
 
-        BUG_ON(data->type != CEPH_MSG_DATA_BIO);
+        BUG_ON(cursor->data->type != CEPH_MSG_DATA_BIO);
 
         bio = cursor->bio;
         BUG_ON(!bio);
@@ -823,10 +823,10 @@ static bool ceph_msg_data_bio_advance(struct ceph_msg_data *data, size_t bytes)
  * For a page array, a piece comes from the first page in the array
  * that has not already been fully consumed.
  */
-static void ceph_msg_data_pages_cursor_init(struct ceph_msg_data *data,
+static void ceph_msg_data_pages_cursor_init(struct ceph_msg_data_cursor *cursor,
                                         size_t length)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
+        struct ceph_msg_data *data = cursor->data;
         int page_count;
 
         BUG_ON(data->type != CEPH_MSG_DATA_PAGES);
@@ -845,11 +845,11 @@ static void ceph_msg_data_pages_cursor_init(struct ceph_msg_data *data,
         cursor->last_piece = (size_t)cursor->page_offset + length <= PAGE_SIZE;
 }
 
-static struct page *ceph_msg_data_pages_next(struct ceph_msg_data *data,
-                                        size_t *page_offset,
-                                        size_t *length)
+static struct page *
+ceph_msg_data_pages_next(struct ceph_msg_data_cursor *cursor,
+                                        size_t *page_offset, size_t *length)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
+        struct ceph_msg_data *data = cursor->data;
 
         BUG_ON(data->type != CEPH_MSG_DATA_PAGES);
 
@@ -865,12 +865,10 @@ static struct page *ceph_msg_data_pages_next(struct ceph_msg_data *data,
         return data->pages[cursor->page_index];
 }
 
-static bool ceph_msg_data_pages_advance(struct ceph_msg_data *data,
+static bool ceph_msg_data_pages_advance(struct ceph_msg_data_cursor *cursor,
                                                 size_t bytes)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
-
-        BUG_ON(data->type != CEPH_MSG_DATA_PAGES);
+        BUG_ON(cursor->data->type != CEPH_MSG_DATA_PAGES);
 
         BUG_ON(cursor->page_offset + bytes > PAGE_SIZE);
 
@@ -894,10 +892,11 @@ static bool ceph_msg_data_pages_advance(struct ceph_msg_data *data,
  * 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_pagelist_cursor_init(struct ceph_msg_data *data,
+static void
+ceph_msg_data_pagelist_cursor_init(struct ceph_msg_data_cursor *cursor,
                                         size_t length)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
+        struct ceph_msg_data *data = cursor->data;
         struct ceph_pagelist *pagelist;
         struct page *page;
 
@@ -919,11 +918,11 @@ static void ceph_msg_data_pagelist_cursor_init(struct ceph_msg_data *data,
         cursor->last_piece = length <= PAGE_SIZE;
 }
 
-static struct page *ceph_msg_data_pagelist_next(struct ceph_msg_data *data,
-                                                size_t *page_offset,
-                                                size_t *length)
+static struct page *
+ceph_msg_data_pagelist_next(struct ceph_msg_data_cursor *cursor,
+                                size_t *page_offset, size_t *length)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
+        struct ceph_msg_data *data = cursor->data;
         struct ceph_pagelist *pagelist;
 
         BUG_ON(data->type != CEPH_MSG_DATA_PAGELIST);
@@ -941,13 +940,13 @@ static struct page *ceph_msg_data_pagelist_next(struct ceph_msg_data *data,
         else
                 *length = PAGE_SIZE - *page_offset;
 
-        return data->cursor->page;
+        return cursor->page;
 }
 
-static bool ceph_msg_data_pagelist_advance(struct ceph_msg_data *data,
+static bool ceph_msg_data_pagelist_advance(struct ceph_msg_data_cursor *cursor,
                                                 size_t bytes)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
+        struct ceph_msg_data *data = cursor->data;
         struct ceph_pagelist *pagelist;
 
         BUG_ON(data->type != CEPH_MSG_DATA_PAGELIST);
@@ -983,19 +982,21 @@ static bool ceph_msg_data_pagelist_advance(struct ceph_msg_data *data,
  * 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,
-                                        size_t length)
+static void ceph_msg_data_cursor_init(struct ceph_msg *msg, size_t length)
 {
-        switch (data->type) {
+        struct ceph_msg_data_cursor *cursor = &msg->cursor;
+
+        cursor->data = msg->data;
+        switch (cursor->data->type) {
         case CEPH_MSG_DATA_PAGELIST:
-                ceph_msg_data_pagelist_cursor_init(data, length);
+                ceph_msg_data_pagelist_cursor_init(cursor, length);
                 break;
         case CEPH_MSG_DATA_PAGES:
-                ceph_msg_data_pages_cursor_init(data, length);
+                ceph_msg_data_pages_cursor_init(cursor, length);
                 break;
 #ifdef CONFIG_BLOCK
         case CEPH_MSG_DATA_BIO:
-                ceph_msg_data_bio_cursor_init(data, length);
+                ceph_msg_data_bio_cursor_init(cursor, length);
                 break;
 #endif /* CONFIG_BLOCK */
         case CEPH_MSG_DATA_NONE:
@@ -1003,7 +1004,7 @@ static void ceph_msg_data_cursor_init(struct ceph_msg_data *data,
                 /* BUG(); */
                 break;
         }
-        data->cursor->need_crc = true;
+        cursor->need_crc = true;
 }
 
 /*
@@ -1011,23 +1012,22 @@ static void ceph_msg_data_cursor_init(struct ceph_msg_data *data,
  * 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,
+static struct page *ceph_msg_data_next(struct ceph_msg_data_cursor *cursor,
+                                        size_t *page_offset, size_t *length,
                                         bool *last_piece)
 {
         struct page *page;
 
-        switch (data->type) {
+        switch (cursor->data->type) {
         case CEPH_MSG_DATA_PAGELIST:
-                page = ceph_msg_data_pagelist_next(data, page_offset, length);
+                page = ceph_msg_data_pagelist_next(cursor, page_offset, length);
                 break;
         case CEPH_MSG_DATA_PAGES:
-                page = ceph_msg_data_pages_next(data, page_offset, length);
+                page = ceph_msg_data_pages_next(cursor, page_offset, length);
                 break;
 #ifdef CONFIG_BLOCK
         case CEPH_MSG_DATA_BIO:
-                page = ceph_msg_data_bio_next(data, page_offset, length);
+                page = ceph_msg_data_bio_next(cursor, page_offset, length);
                 break;
 #endif /* CONFIG_BLOCK */
         case CEPH_MSG_DATA_NONE:
@@ -1039,7 +1039,7 @@ static struct page *ceph_msg_data_next(struct ceph_msg_data *data,
         BUG_ON(*page_offset + *length > PAGE_SIZE);
         BUG_ON(!*length);
         if (last_piece)
-                *last_piece = data->cursor->last_piece;
+                *last_piece = cursor->last_piece;
 
         return page;
 }
@@ -1048,22 +1048,22 @@ static struct page *ceph_msg_data_next(struct ceph_msg_data *data,
  * 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)
+static bool ceph_msg_data_advance(struct ceph_msg_data_cursor *cursor,
+                                size_t bytes)
 {
-        struct ceph_msg_data_cursor *cursor = data->cursor;
         bool new_piece;
 
         BUG_ON(bytes > cursor->resid);
-        switch (data->type) {
+        switch (cursor->data->type) {
         case CEPH_MSG_DATA_PAGELIST:
-                new_piece = ceph_msg_data_pagelist_advance(data, bytes);
+                new_piece = ceph_msg_data_pagelist_advance(cursor, bytes);
                 break;
         case CEPH_MSG_DATA_PAGES:
-                new_piece = ceph_msg_data_pages_advance(data, bytes);
+                new_piece = ceph_msg_data_pages_advance(cursor, bytes);
                 break;
 #ifdef CONFIG_BLOCK
         case CEPH_MSG_DATA_BIO:
-                new_piece = ceph_msg_data_bio_advance(data, bytes);
+                new_piece = ceph_msg_data_bio_advance(cursor, bytes);
                 break;
 #endif /* CONFIG_BLOCK */
         case CEPH_MSG_DATA_NONE:
@@ -1071,7 +1071,7 @@ static bool ceph_msg_data_advance(struct ceph_msg_data *data, size_t bytes)
                 BUG();
                 break;
         }
-        data->cursor->need_crc = new_piece;
+        cursor->need_crc = new_piece;
 
         return new_piece;
 }
@@ -1083,7 +1083,7 @@ static void prepare_message_data(struct ceph_msg *msg, u32 data_len)
 
         /* Initialize data cursor */
 
-        ceph_msg_data_cursor_init(msg->data, (size_t)data_len);
+        ceph_msg_data_cursor_init(msg, (size_t)data_len);
 }
 
 /*
@@ -1404,7 +1404,7 @@ static u32 ceph_crc32c_page(u32 crc, struct page *page,
 static int write_partial_message_data(struct ceph_connection *con)
 {
         struct ceph_msg *msg = con->out_msg;
-        struct ceph_msg_data_cursor *cursor = msg->data->cursor;
+        struct ceph_msg_data_cursor *cursor = &msg->cursor;
         bool do_datacrc = !con->msgr->nocrc;
         u32 crc;
 
@@ -1430,7 +1430,7 @@ static int write_partial_message_data(struct ceph_connection *con)
                 bool need_crc;
                 int ret;
 
-                page = ceph_msg_data_next(msg->data, &page_offset, &length,
+                page = ceph_msg_data_next(&msg->cursor, &page_offset, &length,
                                                         &last_piece);
                 ret = ceph_tcp_sendpage(con->sock, page, page_offset,
                                       length, last_piece);
@@ -1442,7 +1442,7 @@ static int write_partial_message_data(struct ceph_connection *con)
                 }
                 if (do_datacrc && cursor->need_crc)
                         crc = ceph_crc32c_page(crc, page, page_offset, length);
-                need_crc = ceph_msg_data_advance(msg->data, (size_t)ret);
+                need_crc = ceph_msg_data_advance(&msg->cursor, (size_t)ret);
         }
 
         dout("%s %p msg %p done\n", __func__, con, msg);
@@ -2102,7 +2102,7 @@ static int read_partial_message_section(struct ceph_connection *con,
 static int read_partial_msg_data(struct ceph_connection *con)
 {
         struct ceph_msg *msg = con->in_msg;
-        struct ceph_msg_data_cursor *cursor = msg->data->cursor;
+        struct ceph_msg_data_cursor *cursor = &msg->cursor;
         const bool do_datacrc = !con->msgr->nocrc;
         struct page *page;
         size_t page_offset;
@@ -2117,7 +2117,7 @@ static int read_partial_msg_data(struct ceph_connection *con)
         if (do_datacrc)
                 crc = con->in_data_crc;
         while (cursor->resid) {
-                page = ceph_msg_data_next(msg->data, &page_offset, &length,
+                page = ceph_msg_data_next(&msg->cursor, &page_offset, &length,
                                                         NULL);
                 ret = ceph_tcp_recvpage(con->sock, page, page_offset, length);
                 if (ret <= 0) {
@@ -2129,7 +2129,7 @@ static int read_partial_msg_data(struct ceph_connection *con)
 
                 if (do_datacrc)
                         crc = ceph_crc32c_page(crc, page, page_offset, ret);
-                (void) ceph_msg_data_advance(msg->data, (size_t)ret);
+                (void) ceph_msg_data_advance(&msg->cursor, (size_t)ret);
         }
         if (do_datacrc)
                 con->in_data_crc = crc;
@@ -2991,7 +2991,6 @@ void ceph_msg_data_set_pages(struct ceph_msg *msg, struct page **pages,
 
         data = ceph_msg_data_create(CEPH_MSG_DATA_PAGES);
         BUG_ON(!data);
-        data->cursor = &msg->cursor;
         data->pages = pages;
         data->length = length;
         data->alignment = alignment & ~PAGE_MASK;
@@ -3013,7 +3012,6 @@ void ceph_msg_data_set_pagelist(struct ceph_msg *msg,
 
         data = ceph_msg_data_create(CEPH_MSG_DATA_PAGELIST);
         BUG_ON(!data);
-        data->cursor = &msg->cursor;
         data->pagelist = pagelist;
 
         msg->data = data;
@@ -3033,7 +3031,6 @@ void ceph_msg_data_set_bio(struct ceph_msg *msg, struct bio *bio,
 
         data = ceph_msg_data_create(CEPH_MSG_DATA_BIO);
         BUG_ON(!data);
-        data->cursor = &msg->cursor;
         data->bio = bio;
         data->bio_length = length;