libceph: define source request op functions

The rbd code has a function that allocates and populates a
ceph_osd_req_op structure (the in-core version of an osd request
operation).  When reviewed, Josh suggested two things: that the
big varargs function might be better split into type-specific
functions; and that this functionality really belongs in the osd
client rather than rbd.

This patch implements both of Josh's suggestions.  It breaks
up the rbd function into separate functions and defines them
in the osd client module as exported interfaces.  Unlike the
rbd version, however, the functions don't allocate an osd_req_op
structure; they are provided the address of one and that is
initialized instead.

The rbd function has been eliminated and calls to it have been
replaced by calls to the new routines.  The rbd code now now use a
stack (struct) variable to hold the op rather than allocating and
freeing it each time.

For now only the capabilities used by rbd are implemented.
Implementing all the other osd op types, and making the rest of the
code use it will be done separately, in the next few patches.

Note that only the extent, cls, and watch portions of the
ceph_osd_req_op structure are currently used.  Delete the others
(xattr, pgls, and snap) from its definition so nobody thinks it's
actually implemented or needed.  We can add it back again later
if needed, when we know it's been tested.

This (and a few follow-on patches) resolves:
    http://tracker.ceph.com/issues/3861

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

1 files changed, 84 insertions, 0 deletions

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 4e5c0438ea35..02ed72820479 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -289,6 +289,90 @@ static bool osd_req_opcode_valid(u16 opcode)
 	}
 }
 
+/*
+ * This is an osd op init function for opcodes that have no data or
+ * other information associated with them.  It also serves as a
+ * common init routine for all the other init functions, below.
+ */
+void osd_req_op_init(struct ceph_osd_req_op *op, u16 opcode)
+{
+	BUG_ON(!osd_req_opcode_valid(opcode));
+
+	memset(op, 0, sizeof (*op));
+
+	op->op = opcode;
+}
+
+void osd_req_op_extent_init(struct ceph_osd_req_op *op, u16 opcode,
+				u64 offset, u64 length,
+				u64 truncate_size, u32 truncate_seq)
+{
+	size_t payload_len = 0;
+
+	BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE);
+
+	osd_req_op_init(op, opcode);
+
+	op->extent.offset = offset;
+	op->extent.length = length;
+	op->extent.truncate_size = truncate_size;
+	op->extent.truncate_seq = truncate_seq;
+	if (opcode == CEPH_OSD_OP_WRITE)
+		payload_len += length;
+
+	op->payload_len = payload_len;
+}
+EXPORT_SYMBOL(osd_req_op_extent_init);
+
+void osd_req_op_cls_init(struct ceph_osd_req_op *op, u16 opcode,
+			const char *class, const char *method,
+			const void *request_data, size_t request_data_size)
+{
+	size_t payload_len = 0;
+	size_t size;
+
+	BUG_ON(opcode != CEPH_OSD_OP_CALL);
+
+	osd_req_op_init(op, opcode);
+
+	op->cls.class_name = class;
+	size = strlen(class);
+	BUG_ON(size > (size_t) U8_MAX);
+	op->cls.class_len = size;
+	payload_len += size;
+
+	op->cls.method_name = method;
+	size = strlen(method);
+	BUG_ON(size > (size_t) U8_MAX);
+	op->cls.method_len = size;
+	payload_len += size;
+
+	op->cls.indata = request_data;
+	BUG_ON(request_data_size > (size_t) U32_MAX);
+	op->cls.indata_len = (u32) request_data_size;
+	payload_len += request_data_size;
+
+	op->cls.argc = 0;	/* currently unused */
+
+	op->payload_len = payload_len;
+}
+EXPORT_SYMBOL(osd_req_op_cls_init);
+
+void osd_req_op_watch_init(struct ceph_osd_req_op *op, u16 opcode,
+				u64 cookie, u64 version, int flag)
+{
+	BUG_ON(opcode != CEPH_OSD_OP_NOTIFY_ACK && opcode != CEPH_OSD_OP_WATCH);
+
+	osd_req_op_init(op, opcode);
+
+	op->watch.cookie = cookie;
+	/* op->watch.ver = version; */	/* XXX 3847 */
+	op->watch.ver = cpu_to_le64(version);
+	if (opcode == CEPH_OSD_OP_WATCH && flag)
+		op->watch.flag = (u8) 1;
+}
+EXPORT_SYMBOL(osd_req_op_watch_init);
+
 static u64 osd_req_encode_op(struct ceph_osd_request *req,
 			      struct ceph_osd_op *dst,
 			      struct ceph_osd_req_op *src)