libceph: redo callbacks and factor out MOSDOpReply decoding

If you specify ACK | ONDISK and set ->r_unsafe_callback, both
->r_callback and ->r_unsafe_callback(true) are called on ack.  This is
very confusing.  Redo this so that only one of them is called:

    ->r_unsafe_callback(true), on ack
    ->r_unsafe_callback(false), on commit

or

    ->r_callback, on ack|commit

Decode everything in decode_MOSDOpReply() to reduce clutter.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/addr.c

@@ -1765,8 +1765,7 @@ static int __ceph_pool_perm_get(struct ceph_inode_info *ci, u32 pool)
 		goto out_unlock;
 	}
 
-	wr_req->r_flags = CEPH_OSD_FLAG_WRITE |
-			  CEPH_OSD_FLAG_ACK | CEPH_OSD_FLAG_ONDISK;
+	wr_req->r_flags = CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ACK;
 	osd_req_op_init(wr_req, 0, CEPH_OSD_OP_CREATE, CEPH_OSD_OP_FLAG_EXCL);
 	ceph_oloc_copy(&wr_req->r_base_oloc, &rd_req->r_base_oloc);
 	ceph_oid_copy(&wr_req->r_base_oid, &rd_req->r_base_oid);

fs/ceph/file.c

@@ -770,6 +770,8 @@ static void ceph_sync_write_unsafe(struct ceph_osd_request *req, bool unsafe)
 		list_add_tail(&req->r_unsafe_item,
 			      &ci->i_unsafe_writes);
 		spin_unlock(&ci->i_unsafe_lock);
+
+		complete_all(&req->r_completion);
 	} else {
 		spin_lock(&ci->i_unsafe_lock);
 		list_del_init(&req->r_unsafe_item);

include/linux/ceph/osd_client.h

@@ -162,13 +162,14 @@ struct ceph_osd_request {
 	unsigned int		r_num_ops;
 
 	int               r_result;
-	int               r_got_reply;
+	bool              r_got_reply;
 	int		  r_linger;
 
 	struct ceph_osd_client *r_osdc;
 	struct kref       r_kref;
 	bool              r_mempool;
-	struct completion r_completion, r_safe_completion;
+	struct completion r_completion;
+	struct completion r_safe_completion;  /* fsync waiter */
 	ceph_osdc_callback_t r_callback;
 	ceph_osdc_unsafe_callback_t r_unsafe_callback;
 	struct list_head  r_unsafe_item;