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, 50 insertions, 0 deletions

diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index d7b9605fd51d..c7dfcb8a1fb2 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -76,6 +76,7 @@ enum ceph_msg_data_type {
 #ifdef CONFIG_BLOCK
         CEPH_MSG_DATA_BIO,      /* data source/destination is a bio list */
 #endif /* CONFIG_BLOCK */
+        CEPH_MSG_DATA_BVECS,    /* data source/destination is a bio_vec array */
 };
 
 static __inline__ bool ceph_msg_data_type_valid(enum ceph_msg_data_type type)
@@ -87,6 +88,7 @@ static __inline__ bool ceph_msg_data_type_valid(enum ceph_msg_data_type type)
 #ifdef CONFIG_BLOCK
         case CEPH_MSG_DATA_BIO:
 #endif /* CONFIG_BLOCK */
+        case CEPH_MSG_DATA_BVECS:
                 return true;
         default:
                 return false;
@@ -139,6 +141,42 @@ struct ceph_bio_iter {
 
 #endif /* CONFIG_BLOCK */
 
+struct ceph_bvec_iter {
+        struct bio_vec *bvecs;
+        struct bvec_iter iter;
+};
+
+#define __ceph_bvec_iter_advance_step(it, n, STEP) do {                       \
+        BUG_ON((n) > (it)->iter.bi_size);                                     \
+        (void)(STEP);                                                         \
+        bvec_iter_advance((it)->bvecs, &(it)->iter, (n));                     \
+} while (0)
+
+/*
+ * Advance @it by @n bytes.
+ */
+#define ceph_bvec_iter_advance(it, n)                                         \
+        __ceph_bvec_iter_advance_step(it, n, 0)
+
+/*
+ * Advance @it by @n bytes, executing BVEC_STEP for each bio_vec.
+ */
+#define ceph_bvec_iter_advance_step(it, n, BVEC_STEP)                         \
+        __ceph_bvec_iter_advance_step(it, n, ({                               \
+                struct bio_vec bv;                                            \
+                struct bvec_iter __cur_iter;                                  \
+                                                                              \
+                __cur_iter = (it)->iter;                                      \
+                __cur_iter.bi_size = (n);                                     \
+                for_each_bvec(bv, (it)->bvecs, __cur_iter, __cur_iter)        \
+                        (void)(BVEC_STEP);                                    \
+        }))
+
+#define ceph_bvec_iter_shorten(it, n) do {                                    \
+        BUG_ON((n) > (it)->iter.bi_size);                                     \
+        (it)->iter.bi_size = (n);                                             \
+} while (0)
+
 struct ceph_msg_data {
         struct list_head                links;  /* ceph_msg->data */
         enum ceph_msg_data_type         type;
@@ -149,6 +187,7 @@ struct ceph_msg_data {
                         u32                     bio_length;
                 };
 #endif /* CONFIG_BLOCK */
+                struct ceph_bvec_iter   bvec_pos;
                 struct {
                         struct page     **pages;        /* NOT OWNER. */
                         size_t          length;         /* total # bytes */
@@ -170,6 +209,7 @@ struct ceph_msg_data_cursor {
 #ifdef CONFIG_BLOCK
                 struct ceph_bio_iter    bio_iter;
 #endif /* CONFIG_BLOCK */
+                struct bvec_iter        bvec_iter;
                 struct {                                /* pages */
                         unsigned int    page_offset;    /* offset in page */
                         unsigned short  page_index;     /* index in array */
@@ -336,6 +376,8 @@ extern void ceph_msg_data_add_pagelist(struct ceph_msg *msg,
 void ceph_msg_data_add_bio(struct ceph_msg *msg, struct ceph_bio_iter *bio_pos,
                            u32 length);
 #endif /* CONFIG_BLOCK */
+void ceph_msg_data_add_bvecs(struct ceph_msg *msg,
+                             struct ceph_bvec_iter *bvec_pos);
 
 extern struct ceph_msg *ceph_msg_new(int type, int front_len, gfp_t flags,
                                      bool can_fail);
diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index 315691490cb0..528ccc943cee 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -57,6 +57,7 @@ enum ceph_osd_data_type {
 #ifdef CONFIG_BLOCK
         CEPH_OSD_DATA_TYPE_BIO,
 #endif /* CONFIG_BLOCK */
+        CEPH_OSD_DATA_TYPE_BVECS,
 };
 
 struct ceph_osd_data {
@@ -76,6 +77,7 @@ struct ceph_osd_data {
                         u32                     bio_length;
                 };
 #endif /* CONFIG_BLOCK */
+                struct ceph_bvec_iter   bvec_pos;
         };
 };
 
@@ -410,6 +412,9 @@ void osd_req_op_extent_osd_data_bio(struct ceph_osd_request *osd_req,
                                     struct ceph_bio_iter *bio_pos,
                                     u32 bio_length);
 #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);
 
 extern void osd_req_op_cls_request_data_pagelist(struct ceph_osd_request *,
                                         unsigned int which,
@@ -419,6 +424,9 @@ extern void osd_req_op_cls_request_data_pages(struct ceph_osd_request *,
                                         struct page **pages, u64 length,
                                         u32 alignment, bool pages_from_pool,
                                         bool own_pages);
+void osd_req_op_cls_request_data_bvecs(struct ceph_osd_request *osd_req,
+                                       unsigned int which,
+                                       struct bio_vec *bvecs, u32 bytes);
 extern void osd_req_op_cls_response_data_pages(struct ceph_osd_request *,
                                         unsigned int which,
                                         struct page **pages, u64 length,