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The rbd function has been eliminated and calls to it have been
replaced by calls to the new routines.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>

3 files changed, 111 insertions, 116 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 6ed508bd363a..f04d45b6b563 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1134,76 +1134,6 @@ static bool obj_request_type_valid(enum obj_request_type type)
         }
 }
 
-static struct ceph_osd_req_op *rbd_osd_req_op_create(u16 opcode, ...)
-{
-        struct ceph_osd_req_op *op;
-        va_list args;
-        size_t size;
-
-        op = kzalloc(sizeof (*op), GFP_NOIO);
-        if (!op)
-                return NULL;
-        op->op = opcode;
-        va_start(args, opcode);
-        switch (opcode) {
-        case CEPH_OSD_OP_READ:
-        case CEPH_OSD_OP_WRITE:
-                /* rbd_osd_req_op_create(READ, offset, length) */
-                /* rbd_osd_req_op_create(WRITE, offset, length) */
-                op->extent.offset = va_arg(args, u64);
-                op->extent.length = va_arg(args, u64);
-                if (opcode == CEPH_OSD_OP_WRITE)
-                        op->payload_len = op->extent.length;
-                break;
-        case CEPH_OSD_OP_STAT:
-                break;
-        case CEPH_OSD_OP_CALL:
-                /* rbd_osd_req_op_create(CALL, class, method, data, datalen) */
-                op->cls.class_name = va_arg(args, char *);
-                size = strlen(op->cls.class_name);
-                rbd_assert(size <= (size_t) U8_MAX);
-                op->cls.class_len = size;
-                op->payload_len = size;
-
-                op->cls.method_name = va_arg(args, char *);
-                size = strlen(op->cls.method_name);
-                rbd_assert(size <= (size_t) U8_MAX);
-                op->cls.method_len = size;
-                op->payload_len += size;
-
-                op->cls.argc = 0;
-                op->cls.indata = va_arg(args, void *);
-                size = va_arg(args, size_t);
-                rbd_assert(size <= (size_t) U32_MAX);
-                op->cls.indata_len = (u32) size;
-                op->payload_len += size;
-                break;
-        case CEPH_OSD_OP_NOTIFY_ACK:
-        case CEPH_OSD_OP_WATCH:
-                /* rbd_osd_req_op_create(NOTIFY_ACK, cookie, version) */
-                /* rbd_osd_req_op_create(WATCH, cookie, version, flag) */
-                op->watch.cookie = va_arg(args, u64);
-                op->watch.ver = va_arg(args, u64);
-                op->watch.ver = cpu_to_le64(op->watch.ver);
-                if (opcode == CEPH_OSD_OP_WATCH && va_arg(args, int))
-                        op->watch.flag = (u8) 1;
-                break;
-        default:
-                rbd_warn(NULL, "unsupported opcode %hu\n", opcode);
-                kfree(op);
-                op = NULL;
-                break;
-        }
-        va_end(args);
-
-        return op;
-}
-
-static void rbd_osd_req_op_destroy(struct ceph_osd_req_op *op)
-{
-        kfree(op);
-}
-
 static int rbd_obj_request_submit(struct ceph_osd_client *osdc,
                                 struct rbd_obj_request *obj_request)
 {
@@ -1628,7 +1558,7 @@ static int rbd_img_request_fill_bio(struct rbd_img_request *img_request,
         while (resid) {
                 const char *object_name;
                 unsigned int clone_size;
-                struct ceph_osd_req_op *op;
+                struct ceph_osd_req_op op;
                 u64 offset;
                 u64 length;
 
@@ -1657,13 +1587,10 @@ static int rbd_img_request_fill_bio(struct rbd_img_request *img_request,
                  * request.  Note that the contents of the op are
                  * copied by rbd_osd_req_create().
                  */
-                op = rbd_osd_req_op_create(opcode, offset, length);
-                if (!op)
-                        goto out_partial;
+                osd_req_op_extent_init(&op, opcode, offset, length, 0, 0);
                 obj_request->osd_req = rbd_osd_req_create(rbd_dev,
                                                 img_request->write_request,
-                                                obj_request, op);
-                rbd_osd_req_op_destroy(op);
+                                                obj_request, &op);
                 if (!obj_request->osd_req)
                         goto out_partial;
                 /* status and version are initially zero-filled */
@@ -1766,7 +1693,7 @@ static int rbd_obj_notify_ack(struct rbd_device *rbd_dev,
                                    u64 ver, u64 notify_id)
 {
         struct rbd_obj_request *obj_request;
-        struct ceph_osd_req_op *op;
+        struct ceph_osd_req_op op;
         struct ceph_osd_client *osdc;
         int ret;
 
@@ -1776,12 +1703,9 @@ static int rbd_obj_notify_ack(struct rbd_device *rbd_dev,
                 return -ENOMEM;
 
         ret = -ENOMEM;
-        op = rbd_osd_req_op_create(CEPH_OSD_OP_NOTIFY_ACK, notify_id, ver);
-        if (!op)
-                goto out;
+        osd_req_op_watch_init(&op, CEPH_OSD_OP_NOTIFY_ACK, notify_id, ver, 0);
         obj_request->osd_req = rbd_osd_req_create(rbd_dev, false,
-                                                obj_request, op);
-        rbd_osd_req_op_destroy(op);
+                                                obj_request, &op);
         if (!obj_request->osd_req)
                 goto out;
 
@@ -1823,7 +1747,7 @@ static int rbd_dev_header_watch_sync(struct rbd_device *rbd_dev, int start)
 {
         struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
         struct rbd_obj_request *obj_request;
-        struct ceph_osd_req_op *op;
+        struct ceph_osd_req_op op;
         int ret;
 
         rbd_assert(start ^ !!rbd_dev->watch_event);
@@ -1843,14 +1767,11 @@ static int rbd_dev_header_watch_sync(struct rbd_device *rbd_dev, int start)
         if (!obj_request)
                 goto out_cancel;
 
-        op = rbd_osd_req_op_create(CEPH_OSD_OP_WATCH,
+        osd_req_op_watch_init(&op, CEPH_OSD_OP_WATCH,
                                 rbd_dev->watch_event->cookie,
                                 rbd_dev->header.obj_version, start);
-        if (!op)
-                goto out_cancel;
         obj_request->osd_req = rbd_osd_req_create(rbd_dev, true,
-                                                        obj_request, op);
-        rbd_osd_req_op_destroy(op);
+                                                        obj_request, &op);
         if (!obj_request->osd_req)
                 goto out_cancel;
 
@@ -1912,7 +1833,7 @@ static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
 {
         struct rbd_obj_request *obj_request;
         struct ceph_osd_client *osdc;
-        struct ceph_osd_req_op *op;
+        struct ceph_osd_req_op op;
         struct page **pages;
         u32 page_count;
         int ret;
@@ -1939,13 +1860,10 @@ static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
         obj_request->pages = pages;
         obj_request->page_count = page_count;
 
-        op = rbd_osd_req_op_create(CEPH_OSD_OP_CALL, class_name,
-                                        method_name, outbound, outbound_size);
-        if (!op)
-                goto out;
+        osd_req_op_cls_init(&op, CEPH_OSD_OP_CALL, class_name, method_name,
+                                        outbound, outbound_size);
         obj_request->osd_req = rbd_osd_req_create(rbd_dev, false,
-                                                obj_request, op);
-        rbd_osd_req_op_destroy(op);
+                                                obj_request, &op);
         if (!obj_request->osd_req)
                 goto out;
 
@@ -2125,7 +2043,7 @@ static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
                                 char *buf, u64 *version)
 
 {
-        struct ceph_osd_req_op *op;
+        struct ceph_osd_req_op op;
         struct rbd_obj_request *obj_request;
         struct ceph_osd_client *osdc;
         struct page **pages = NULL;
@@ -2147,12 +2065,9 @@ static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
         obj_request->pages = pages;
         obj_request->page_count = page_count;
 
-        op = rbd_osd_req_op_create(CEPH_OSD_OP_READ, offset, length);
-        if (!op)
-                goto out;
+        osd_req_op_extent_init(&op, CEPH_OSD_OP_READ, offset, length, 0, 0);
         obj_request->osd_req = rbd_osd_req_create(rbd_dev, false,
-                                                obj_request, op);
-        rbd_osd_req_op_destroy(op);
+                                                obj_request, &op);
         if (!obj_request->osd_req)
                 goto out;
 
diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index 1dab291b2dc6..5fd2cbfcfd91 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -202,14 +202,6 @@ struct ceph_osd_req_op {
                         u32 truncate_seq;
                 } extent;
                 struct {
-                        const char *name;
-                        const void *val;
-                        u32 name_len;
-                        u32 value_len;
-                        __u8 cmp_op;       /* CEPH_OSD_CMPXATTR_OP_* */
-                        __u8 cmp_mode;     /* CEPH_OSD_CMPXATTR_MODE_* */
-                } xattr;
-                struct {
                         const char *class_name;
                         const char *method_name;
                         const void *indata;
@@ -220,13 +212,6 @@ struct ceph_osd_req_op {
                 } cls;
                 struct {
                         u64 cookie;
-                        u64 count;
-                } pgls;
-                struct {
-                        u64 snapid;
-                } snap;
-                struct {
-                        u64 cookie;
                         u64 ver;
                         u32 prot_ver;
                         u32 timeout;
@@ -244,6 +229,17 @@ extern void ceph_osdc_handle_reply(struct ceph_osd_client *osdc,
 extern void ceph_osdc_handle_map(struct ceph_osd_client *osdc,
                                  struct ceph_msg *msg);
 
+extern void osd_req_op_init(struct ceph_osd_req_op *op, u16 opcode);
+extern void osd_req_op_extent_init(struct ceph_osd_req_op *op, u16 opcode,
+                                        u64 offset, u64 length,
+                                        u64 truncate_size, u32 truncate_seq);
+extern 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);
+extern void osd_req_op_watch_init(struct ceph_osd_req_op *op, u16 opcode,
+                                        u64 cookie, u64 version, int flag);
+
 extern struct ceph_osd_request *ceph_osdc_alloc_request(struct ceph_osd_client *osdc,
                                                struct ceph_snap_context *snapc,
                                                unsigned int num_op,
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)