libceph: add CEPH_OSD_OP_ASSERT_VER support

...and record the user_version in the reply in a new field in
ceph_osd_request, so we can populate the assert_ver appropriately.
Shuffle the fields a bit too so that the new field fits in an
existing hole on x86_64.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-and-tested-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Author: jtlayton

include/linux/ceph/osd_client.h

@@ -198,6 +198,9 @@ struct ceph_osd_req_op {
 			u32 src_fadvise_flags;
 			struct ceph_osd_data osd_data;
 		} copy_from;
+		struct {
+			u64 ver;
+		} assert_ver;
 	};
 };
 
@@ -252,6 +255,7 @@ struct ceph_osd_request {
 	struct ceph_osd_client *r_osdc;
 	struct kref       r_kref;
 	bool              r_mempool;
+	bool		  r_linger;           /* don't resend on failure */
 	struct completion r_completion;       /* private to osd_client.c */
 	ceph_osdc_callback_t r_callback;
 
@@ -264,9 +268,9 @@ struct ceph_osd_request {
 	struct ceph_snap_context *r_snapc;    /* for writes */
 	struct timespec64 r_mtime;            /* ditto */
 	u64 r_data_offset;                    /* ditto */
-	bool r_linger;                        /* don't resend on failure */
 
 	/* internal */
+	u64 r_version;			      /* data version sent in reply */
 	unsigned long r_stamp;                /* jiffies, send or check time */
 	unsigned long r_start_stamp;          /* jiffies */
 	ktime_t r_start_latency;              /* ktime_t */

include/linux/ceph/rados.h

@@ -523,6 +523,10 @@ struct ceph_osd_op {
 		struct {
 			__le64 cookie;
 		} __attribute__ ((packed)) notify;
+		struct {
+			__le64 unused;
+			__le64 ver;
+		} __attribute__ ((packed)) assert_ver;
 		struct {
 			__le64 offset, length;
 			__le64 src_offset;

net/ceph/osd_client.c

@@ -1048,6 +1048,10 @@ static u32 osd_req_encode_op(struct ceph_osd_op *dst,
 		dst->copy_from.src_fadvise_flags =
 			cpu_to_le32(src->copy_from.src_fadvise_flags);
 		break;
+	case CEPH_OSD_OP_ASSERT_VER:
+		dst->assert_ver.unused = cpu_to_le64(0);
+		dst->assert_ver.ver = cpu_to_le64(src->assert_ver.ver);
+		break;
 	default:
 		pr_err("unsupported osd opcode %s\n",
 			ceph_osd_op_name(src->op));
@@ -3859,6 +3863,7 @@ static void handle_reply(struct ceph_osd *osd, struct ceph_msg *msg)
 	 * one (type of) reply back.
 	 */
 	WARN_ON(!(m.flags & CEPH_OSD_FLAG_ONDISK));
+	req->r_version = m.user_version;
 	req->r_result = m.result ?: data_len;
 	finish_request(req);
 	mutex_unlock(&osd->lock);