libceph: introduce BVECS data type

In preparation for rbd "fancy" striping, introduce ceph_bvec_iter for
working with bio_vec array data buffers.  The wrappers are trivial, but
make it look similar to ceph_bio_iter.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

2 files changed, 114 insertions, 0 deletions

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index b9fa8b869c08..91a57857cf11 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -894,6 +894,58 @@ static bool ceph_msg_data_bio_advance(struct ceph_msg_data_cursor *cursor,
 }
 #endif /* CONFIG_BLOCK */
 
+static void ceph_msg_data_bvecs_cursor_init(struct ceph_msg_data_cursor *cursor,
+                                        size_t length)
+{
+        struct ceph_msg_data *data = cursor->data;
+        struct bio_vec *bvecs = data->bvec_pos.bvecs;
+
+        cursor->resid = min_t(size_t, length, data->bvec_pos.iter.bi_size);
+        cursor->bvec_iter = data->bvec_pos.iter;
+        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,
+                                                size_t *page_offset,
+                                                size_t *length)
+{
+        struct bio_vec bv = bvec_iter_bvec(cursor->data->bvec_pos.bvecs,
+                                           cursor->bvec_iter);
+
+        *page_offset = bv.bv_offset;
+        *length = bv.bv_len;
+        return bv.bv_page;
+}
+
+static bool ceph_msg_data_bvecs_advance(struct ceph_msg_data_cursor *cursor,
+                                        size_t bytes)
+{
+        struct bio_vec *bvecs = cursor->data->bvec_pos.bvecs;
+
+        BUG_ON(bytes > cursor->resid);
+        BUG_ON(bytes > bvec_iter_len(bvecs, cursor->bvec_iter));
+        cursor->resid -= bytes;
+        bvec_iter_advance(bvecs, &cursor->bvec_iter, bytes);
+
+        if (!cursor->resid) {
+                BUG_ON(!cursor->last_piece);
+                return false;   /* no more data */
+        }
+
+        if (!bytes || cursor->bvec_iter.bi_bvec_done)
+                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;
+}
+
 /*
  * For a page array, a piece comes from the first page in the array
  * that has not already been fully consumed.
@@ -1077,6 +1129,9 @@ static void __ceph_msg_data_cursor_init(struct ceph_msg_data_cursor *cursor)
                 ceph_msg_data_bio_cursor_init(cursor, length);
                 break;
 #endif /* CONFIG_BLOCK */
+        case CEPH_MSG_DATA_BVECS:
+                ceph_msg_data_bvecs_cursor_init(cursor, length);
+                break;
         case CEPH_MSG_DATA_NONE:
         default:
                 /* BUG(); */
@@ -1125,6 +1180,9 @@ static struct page *ceph_msg_data_next(struct ceph_msg_data_cursor *cursor,
                 page = ceph_msg_data_bio_next(cursor, page_offset, length);
                 break;
 #endif /* CONFIG_BLOCK */
+        case CEPH_MSG_DATA_BVECS:
+                page = ceph_msg_data_bvecs_next(cursor, page_offset, length);
+                break;
         case CEPH_MSG_DATA_NONE:
         default:
                 page = NULL;
@@ -1163,6 +1221,9 @@ static void ceph_msg_data_advance(struct ceph_msg_data_cursor *cursor,
                 new_piece = ceph_msg_data_bio_advance(cursor, bytes);
                 break;
 #endif /* CONFIG_BLOCK */
+        case CEPH_MSG_DATA_BVECS:
+                new_piece = ceph_msg_data_bvecs_advance(cursor, bytes);
+                break;
         case CEPH_MSG_DATA_NONE:
         default:
                 BUG();
@@ -3247,6 +3308,20 @@ void ceph_msg_data_add_bio(struct ceph_msg *msg, struct ceph_bio_iter *bio_pos,
 EXPORT_SYMBOL(ceph_msg_data_add_bio);
 #endif  /* CONFIG_BLOCK */
 
+void ceph_msg_data_add_bvecs(struct ceph_msg *msg,
+                             struct ceph_bvec_iter *bvec_pos)
+{
+        struct ceph_msg_data *data;
+
+        data = ceph_msg_data_create(CEPH_MSG_DATA_BVECS);
+        BUG_ON(!data);
+        data->bvec_pos = *bvec_pos;
+
+        list_add_tail(&data->links, &msg->data);
+        msg->data_length += bvec_pos->iter.bi_size;
+}
+EXPORT_SYMBOL(ceph_msg_data_add_bvecs);
+
 /*
  * construct a new message with given type, size
  * the new msg has a ref count of 1.
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 339d8773ebe8..407be0533c18 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -155,6 +155,13 @@ static void ceph_osd_data_bio_init(struct ceph_osd_data *osd_data,
 }
 #endif /* CONFIG_BLOCK */
 
+static void ceph_osd_data_bvecs_init(struct ceph_osd_data *osd_data,
+                                     struct ceph_bvec_iter *bvec_pos)
+{
+        osd_data->type = CEPH_OSD_DATA_TYPE_BVECS;
+        osd_data->bvec_pos = *bvec_pos;
+}
+
 #define osd_req_op_data(oreq, whch, typ, fld)                           \
 ({                                                                      \
         struct ceph_osd_request *__oreq = (oreq);                       \
@@ -229,6 +236,17 @@ void osd_req_op_extent_osd_data_bio(struct ceph_osd_request *osd_req,
 EXPORT_SYMBOL(osd_req_op_extent_osd_data_bio);
 #endif /* CONFIG_BLOCK */
 
+void osd_req_op_extent_osd_data_bvec_pos(struct ceph_osd_request *osd_req,
+                                         unsigned int which,
+                                         struct ceph_bvec_iter *bvec_pos)
+{
+        struct ceph_osd_data *osd_data;
+
+        osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
+        ceph_osd_data_bvecs_init(osd_data, bvec_pos);
+}
+EXPORT_SYMBOL(osd_req_op_extent_osd_data_bvec_pos);
+
 static void osd_req_op_cls_request_info_pagelist(
                         struct ceph_osd_request *osd_req,
                         unsigned int which, struct ceph_pagelist *pagelist)
@@ -266,6 +284,23 @@ void osd_req_op_cls_request_data_pages(struct ceph_osd_request *osd_req,
 }
 EXPORT_SYMBOL(osd_req_op_cls_request_data_pages);
 
+void osd_req_op_cls_request_data_bvecs(struct ceph_osd_request *osd_req,
+                                       unsigned int which,
+                                       struct bio_vec *bvecs, u32 bytes)
+{
+        struct ceph_osd_data *osd_data;
+        struct ceph_bvec_iter it = {
+                .bvecs = bvecs,
+                .iter = { .bi_size = bytes },
+        };
+
+        osd_data = osd_req_op_data(osd_req, which, cls, request_data);
+        ceph_osd_data_bvecs_init(osd_data, &it);
+        osd_req->r_ops[which].cls.indata_len += bytes;
+        osd_req->r_ops[which].indata_len += bytes;
+}
+EXPORT_SYMBOL(osd_req_op_cls_request_data_bvecs);
+
 void osd_req_op_cls_response_data_pages(struct ceph_osd_request *osd_req,
                         unsigned int which, struct page **pages, u64 length,
                         u32 alignment, bool pages_from_pool, bool own_pages)
@@ -291,6 +326,8 @@ static u64 ceph_osd_data_length(struct ceph_osd_data *osd_data)
         case CEPH_OSD_DATA_TYPE_BIO:
                 return (u64)osd_data->bio_length;
 #endif /* CONFIG_BLOCK */
+        case CEPH_OSD_DATA_TYPE_BVECS:
+                return osd_data->bvec_pos.iter.bi_size;
         default:
                 WARN(true, "unrecognized data type %d\n", (int)osd_data->type);
                 return 0;
@@ -831,6 +868,8 @@ static void ceph_osdc_msg_data_add(struct ceph_msg *msg,
         } else if (osd_data->type == CEPH_OSD_DATA_TYPE_BIO) {
                 ceph_msg_data_add_bio(msg, &osd_data->bio_pos, length);
 #endif
+        } else if (osd_data->type == CEPH_OSD_DATA_TYPE_BVECS) {
+                ceph_msg_data_add_bvecs(msg, &osd_data->bvec_pos);
         } else {
                 BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_NONE);
         }