1 files changed, 337 insertions, 70 deletions

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 11c04e7d928e..6664ea73ccf8 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -171,6 +171,13 @@ static void ceph_osd_data_bvecs_init(struct ceph_osd_data *osd_data,
 	osd_data->num_bvecs = num_bvecs;
 }
 
+static void ceph_osd_iter_init(struct ceph_osd_data *osd_data,
+			       struct iov_iter *iter)
+{
+	osd_data->type = CEPH_OSD_DATA_TYPE_ITER;
+	osd_data->iter = *iter;
+}
+
 static struct ceph_osd_data *
 osd_req_op_raw_data_in(struct ceph_osd_request *osd_req, unsigned int which)
 {
@@ -213,16 +220,6 @@ void osd_req_op_extent_osd_data_pages(struct ceph_osd_request *osd_req,
 }
 EXPORT_SYMBOL(osd_req_op_extent_osd_data_pages);
 
-void osd_req_op_extent_osd_data_pagelist(struct ceph_osd_request *osd_req,
-			unsigned int which, struct ceph_pagelist *pagelist)
-{
-	struct ceph_osd_data *osd_data;
-
-	osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
-	ceph_osd_data_pagelist_init(osd_data, pagelist);
-}
-EXPORT_SYMBOL(osd_req_op_extent_osd_data_pagelist);
-
 #ifdef CONFIG_BLOCK
 void osd_req_op_extent_osd_data_bio(struct ceph_osd_request *osd_req,
 				    unsigned int which,
@@ -264,28 +261,31 @@ void osd_req_op_extent_osd_data_bvec_pos(struct ceph_osd_request *osd_req,
 }
 EXPORT_SYMBOL(osd_req_op_extent_osd_data_bvec_pos);
 
-static void osd_req_op_cls_request_info_pagelist(
-			struct ceph_osd_request *osd_req,
-			unsigned int which, struct ceph_pagelist *pagelist)
+/**
+ * osd_req_op_extent_osd_iter - Set up an operation with an iterator buffer
+ * @osd_req: The request to set up
+ * @which: Index of the operation in which to set the iter
+ * @iter: The buffer iterator
+ */
+void osd_req_op_extent_osd_iter(struct ceph_osd_request *osd_req,
+				unsigned int which, struct iov_iter *iter)
 {
 	struct ceph_osd_data *osd_data;
 
-	osd_data = osd_req_op_data(osd_req, which, cls, request_info);
-	ceph_osd_data_pagelist_init(osd_data, pagelist);
+	osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
+	ceph_osd_iter_init(osd_data, iter);
 }
+EXPORT_SYMBOL(osd_req_op_extent_osd_iter);
 
-void osd_req_op_cls_request_data_pagelist(
+static void osd_req_op_cls_request_info_pagelist(
 			struct ceph_osd_request *osd_req,
 			unsigned int which, struct ceph_pagelist *pagelist)
 {
 	struct ceph_osd_data *osd_data;
 
-	osd_data = osd_req_op_data(osd_req, which, cls, request_data);
+	osd_data = osd_req_op_data(osd_req, which, cls, request_info);
 	ceph_osd_data_pagelist_init(osd_data, pagelist);
-	osd_req->r_ops[which].cls.indata_len += pagelist->length;
-	osd_req->r_ops[which].indata_len += pagelist->length;
 }
-EXPORT_SYMBOL(osd_req_op_cls_request_data_pagelist);
 
 void osd_req_op_cls_request_data_pages(struct ceph_osd_request *osd_req,
 			unsigned int which, struct page **pages, u64 length,
@@ -346,6 +346,8 @@ static u64 ceph_osd_data_length(struct ceph_osd_data *osd_data)
 #endif /* CONFIG_BLOCK */
 	case CEPH_OSD_DATA_TYPE_BVECS:
 		return osd_data->bvec_pos.iter.bi_size;
+	case CEPH_OSD_DATA_TYPE_ITER:
+		return iov_iter_count(&osd_data->iter);
 	default:
 		WARN(true, "unrecognized data type %d\n", (int)osd_data->type);
 		return 0;
@@ -376,8 +378,10 @@ static void osd_req_op_data_release(struct ceph_osd_request *osd_req,
 
 	switch (op->op) {
 	case CEPH_OSD_OP_READ:
+	case CEPH_OSD_OP_SPARSE_READ:
 	case CEPH_OSD_OP_WRITE:
 	case CEPH_OSD_OP_WRITEFULL:
+		kfree(op->extent.sparse_ext);
 		ceph_osd_data_release(&op->extent.osd_data);
 		break;
 	case CEPH_OSD_OP_CALL:
@@ -669,6 +673,7 @@ static void get_num_data_items(struct ceph_osd_request *req,
 		/* reply */
 		case CEPH_OSD_OP_STAT:
 		case CEPH_OSD_OP_READ:
+		case CEPH_OSD_OP_SPARSE_READ:
 		case CEPH_OSD_OP_LIST_WATCHERS:
 			*num_reply_data_items += 1;
 			break;
@@ -738,7 +743,7 @@ void osd_req_op_extent_init(struct ceph_osd_request *osd_req,
 
 	BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
 	       opcode != CEPH_OSD_OP_WRITEFULL && opcode != CEPH_OSD_OP_ZERO &&
-	       opcode != CEPH_OSD_OP_TRUNCATE);
+	       opcode != CEPH_OSD_OP_TRUNCATE && opcode != CEPH_OSD_OP_SPARSE_READ);
 
 	op->extent.offset = offset;
 	op->extent.length = length;
@@ -951,6 +956,8 @@ static void ceph_osdc_msg_data_add(struct ceph_msg *msg,
 #endif
 	} else if (osd_data->type == CEPH_OSD_DATA_TYPE_BVECS) {
 		ceph_msg_data_add_bvecs(msg, &osd_data->bvec_pos);
+	} else if (osd_data->type == CEPH_OSD_DATA_TYPE_ITER) {
+		ceph_msg_data_add_iter(msg, &osd_data->iter);
 	} else {
 		BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_NONE);
 	}
@@ -963,6 +970,7 @@ static u32 osd_req_encode_op(struct ceph_osd_op *dst,
 	case CEPH_OSD_OP_STAT:
 		break;
 	case CEPH_OSD_OP_READ:
+	case CEPH_OSD_OP_SPARSE_READ:
 	case CEPH_OSD_OP_WRITE:
 	case CEPH_OSD_OP_WRITEFULL:
 	case CEPH_OSD_OP_ZERO:
@@ -1017,6 +1025,10 @@ 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));
@@ -1059,7 +1071,8 @@ struct ceph_osd_request *ceph_osdc_new_request(struct ceph_osd_client *osdc,
 
 	BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
 	       opcode != CEPH_OSD_OP_ZERO && opcode != CEPH_OSD_OP_TRUNCATE &&
-	       opcode != CEPH_OSD_OP_CREATE && opcode != CEPH_OSD_OP_DELETE);
+	       opcode != CEPH_OSD_OP_CREATE && opcode != CEPH_OSD_OP_DELETE &&
+	       opcode != CEPH_OSD_OP_SPARSE_READ);
 
 	req = ceph_osdc_alloc_request(osdc, snapc, num_ops, use_mempool,
 					GFP_NOFS);
@@ -1100,15 +1113,30 @@ struct ceph_osd_request *ceph_osdc_new_request(struct ceph_osd_client *osdc,
 	if (flags & CEPH_OSD_FLAG_WRITE)
 		req->r_data_offset = off;
 
-	if (num_ops > 1)
+	if (num_ops > 1) {
+		int num_req_ops, num_rep_ops;
+
 		/*
-		 * This is a special case for ceph_writepages_start(), but it
-		 * also covers ceph_uninline_data().  If more multi-op request
-		 * use cases emerge, we will need a separate helper.
+		 * If this is a multi-op write request, assume that we'll need
+		 * request ops. If it's a multi-op read then assume we'll need
+		 * reply ops. Anything else and call it -EINVAL.
 		 */
-		r = __ceph_osdc_alloc_messages(req, GFP_NOFS, num_ops, 0);
-	else
+		if (flags & CEPH_OSD_FLAG_WRITE) {
+			num_req_ops = num_ops;
+			num_rep_ops = 0;
+		} else if (flags & CEPH_OSD_FLAG_READ) {
+			num_req_ops = 0;
+			num_rep_ops = num_ops;
+		} else {
+			r = -EINVAL;
+			goto fail;
+		}
+
+		r = __ceph_osdc_alloc_messages(req, GFP_NOFS, num_req_ops,
+					       num_rep_ops);
+	} else {
 		r = ceph_osdc_alloc_messages(req, GFP_NOFS);
+	}
 	if (r)
 		goto fail;
 
@@ -1120,6 +1148,20 @@ fail:
 }
 EXPORT_SYMBOL(ceph_osdc_new_request);
 
+int __ceph_alloc_sparse_ext_map(struct ceph_osd_req_op *op, int cnt)
+{
+	WARN_ON(op->op != CEPH_OSD_OP_SPARSE_READ);
+
+	op->extent.sparse_ext_cnt = cnt;
+	op->extent.sparse_ext = kmalloc_array(cnt,
+					      sizeof(*op->extent.sparse_ext),
+					      GFP_NOFS);
+	if (!op->extent.sparse_ext)
+		return -ENOMEM;
+	return 0;
+}
+EXPORT_SYMBOL(__ceph_alloc_sparse_ext_map);
+
 /*
  * We keep osd requests in an rbtree, sorted by ->r_tid.
  */
@@ -1177,6 +1219,7 @@ static void osd_init(struct ceph_osd *osd)
 {
 	refcount_set(&osd->o_ref, 1);
 	RB_CLEAR_NODE(&osd->o_node);
+	spin_lock_init(&osd->o_requests_lock);
 	osd->o_requests = RB_ROOT;
 	osd->o_linger_requests = RB_ROOT;
 	osd->o_backoff_mappings = RB_ROOT;
@@ -1187,6 +1230,13 @@ static void osd_init(struct ceph_osd *osd)
 	mutex_init(&osd->lock);
 }
 
+static void ceph_init_sparse_read(struct ceph_sparse_read *sr)
+{
+	kfree(sr->sr_extent);
+	memset(sr, '\0', sizeof(*sr));
+	sr->sr_state = CEPH_SPARSE_READ_HDR;
+}
+
 static void osd_cleanup(struct ceph_osd *osd)
 {
 	WARN_ON(!RB_EMPTY_NODE(&osd->o_node));
@@ -1197,6 +1247,8 @@ static void osd_cleanup(struct ceph_osd *osd)
 	WARN_ON(!list_empty(&osd->o_osd_lru));
 	WARN_ON(!list_empty(&osd->o_keepalive_item));
 
+	ceph_init_sparse_read(&osd->o_sparse_read);
+
 	if (osd->o_auth.authorizer) {
 		WARN_ON(osd_homeless(osd));
 		ceph_auth_destroy_authorizer(osd->o_auth.authorizer);
@@ -1216,6 +1268,9 @@ static struct ceph_osd *create_osd(struct ceph_osd_client *osdc, int onum)
 	osd_init(osd);
 	osd->o_osdc = osdc;
 	osd->o_osd = onum;
+	osd->o_sparse_op_idx = -1;
+
+	ceph_init_sparse_read(&osd->o_sparse_read);
 
 	ceph_con_init(&osd->o_con, osd, &osd_con_ops, &osdc->client->msgr);
 
@@ -1406,7 +1461,9 @@ static void link_request(struct ceph_osd *osd, struct ceph_osd_request *req)
 		atomic_inc(&osd->o_osdc->num_homeless);
 
 	get_osd(osd);
+	spin_lock(&osd->o_requests_lock);
 	insert_request(&osd->o_requests, req);
+	spin_unlock(&osd->o_requests_lock);
 	req->r_osd = osd;
 }
 
@@ -1418,7 +1475,9 @@ static void unlink_request(struct ceph_osd *osd, struct ceph_osd_request *req)
 	     req, req->r_tid);
 
 	req->r_osd = NULL;
+	spin_lock(&osd->o_requests_lock);
 	erase_request(&osd->o_requests, req);
+	spin_unlock(&osd->o_requests_lock);
 	put_osd(osd);
 
 	if (!osd_homeless(osd))
@@ -2016,6 +2075,7 @@ static void setup_request_data(struct ceph_osd_request *req)
 					       &op->raw_data_in);
 			break;
 		case CEPH_OSD_OP_READ:
+		case CEPH_OSD_OP_SPARSE_READ:
 			ceph_osdc_msg_data_add(reply_msg,
 					       &op->extent.osd_data);
 			break;
@@ -2435,8 +2495,10 @@ static void finish_request(struct ceph_osd_request *req)
 
 	req->r_end_latency = ktime_get();
 
-	if (req->r_osd)
+	if (req->r_osd) {
+		ceph_init_sparse_read(&req->r_osd->o_sparse_read);
 		unlink_request(req->r_osd, req);
+	}
 	atomic_dec(&osdc->num_requests);
 
 	/*
@@ -3334,17 +3396,24 @@ static int linger_reg_commit_wait(struct ceph_osd_linger_request *lreq)
 	int ret;
 
 	dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);
-	ret = wait_for_completion_interruptible(&lreq->reg_commit_wait);
+	ret = wait_for_completion_killable(&lreq->reg_commit_wait);
 	return ret ?: lreq->reg_commit_error;
 }
 
-static int linger_notify_finish_wait(struct ceph_osd_linger_request *lreq)
+static int linger_notify_finish_wait(struct ceph_osd_linger_request *lreq,
+				     unsigned long timeout)
 {
-	int ret;
+	long left;
 
 	dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);
-	ret = wait_for_completion_interruptible(&lreq->notify_finish_wait);
-	return ret ?: lreq->notify_finish_error;
+	left = wait_for_completion_killable_timeout(&lreq->notify_finish_wait,
+						ceph_timeout_jiffies(timeout));
+	if (left <= 0)
+		left = left ?: -ETIMEDOUT;
+	else
+		left = lreq->notify_finish_error; /* completed */
+
+	return left;
 }
 
 /*
@@ -3788,6 +3857,7 @@ 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);
@@ -4896,7 +4966,8 @@ int ceph_osdc_notify(struct ceph_osd_client *osdc,
 	linger_submit(lreq);
 	ret = linger_reg_commit_wait(lreq);
 	if (!ret)
-		ret = linger_notify_finish_wait(lreq);
+		ret = linger_notify_finish_wait(lreq,
+				 msecs_to_jiffies(2 * timeout * MSEC_PER_SEC));
 	else
 		dout("lreq %p failed to initiate notify %d\n", lreq, ret);
 
@@ -4907,40 +4978,6 @@ out_put_lreq:
 }
 EXPORT_SYMBOL(ceph_osdc_notify);
 
-/*
- * Return the number of milliseconds since the watch was last
- * confirmed, or an error.  If there is an error, the watch is no
- * longer valid, and should be destroyed with ceph_osdc_unwatch().
- */
-int ceph_osdc_watch_check(struct ceph_osd_client *osdc,
-			  struct ceph_osd_linger_request *lreq)
-{
-	unsigned long stamp, age;
-	int ret;
-
-	down_read(&osdc->lock);
-	mutex_lock(&lreq->lock);
-	stamp = lreq->watch_valid_thru;
-	if (!list_empty(&lreq->pending_lworks)) {
-		struct linger_work *lwork =
-		    list_first_entry(&lreq->pending_lworks,
-				     struct linger_work,
-				     pending_item);
-
-		if (time_before(lwork->queued_stamp, stamp))
-			stamp = lwork->queued_stamp;
-	}
-	age = jiffies - stamp;
-	dout("%s lreq %p linger_id %llu age %lu last_error %d\n", __func__,
-	     lreq, lreq->linger_id, age, lreq->last_error);
-	/* we are truncating to msecs, so return a safe upper bound */
-	ret = lreq->last_error ?: 1 + jiffies_to_msecs(age);
-
-	mutex_unlock(&lreq->lock);
-	up_read(&osdc->lock);
-	return ret;
-}
-
 static int decode_watcher(void **p, void *end, struct ceph_watch_item *item)
 {
 	u8 struct_v;
@@ -5340,6 +5377,24 @@ static void osd_dispatch(struct ceph_connection *con, struct ceph_msg *msg)
 	ceph_msg_put(msg);
 }
 
+/* How much sparse data was requested? */
+static u64 sparse_data_requested(struct ceph_osd_request *req)
+{
+	u64 len = 0;
+
+	if (req->r_flags & CEPH_OSD_FLAG_READ) {
+		int i;
+
+		for (i = 0; i < req->r_num_ops; ++i) {
+			struct ceph_osd_req_op *op = &req->r_ops[i];
+
+			if (op->op == CEPH_OSD_OP_SPARSE_READ)
+				len += op->extent.length;
+		}
+	}
+	return len;
+}
+
 /*
  * Lookup and return message for incoming reply.  Don't try to do
  * anything about a larger than preallocated data portion of the
@@ -5356,6 +5411,7 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
 	int front_len = le32_to_cpu(hdr->front_len);
 	int data_len = le32_to_cpu(hdr->data_len);
 	u64 tid = le64_to_cpu(hdr->tid);
+	u64 srlen;
 
 	down_read(&osdc->lock);
 	if (!osd_registered(osd)) {
@@ -5388,7 +5444,8 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
 		req->r_reply = m;
 	}
 
-	if (data_len > req->r_reply->data_length) {
+	srlen = sparse_data_requested(req);
+	if (!srlen && data_len > req->r_reply->data_length) {
 		pr_warn("%s osd%d tid %llu data %d > preallocated %zu, skipping\n",
 			__func__, osd->o_osd, req->r_tid, data_len,
 			req->r_reply->data_length);
@@ -5398,6 +5455,8 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
 	}
 
 	m = ceph_msg_get(req->r_reply);
+	m->sparse_read_total = srlen;
+
 	dout("get_reply tid %lld %p\n", tid, m);
 
 out_unlock_session:
@@ -5630,9 +5689,217 @@ static int osd_check_message_signature(struct ceph_msg *msg)
 	return ceph_auth_check_message_signature(auth, msg);
 }
 
+static void advance_cursor(struct ceph_msg_data_cursor *cursor, size_t len,
+			   bool zero)
+{
+	while (len) {
+		struct page *page;
+		size_t poff, plen;
+
+		page = ceph_msg_data_next(cursor, &poff, &plen);
+		if (plen > len)
+			plen = len;
+		if (zero)
+			zero_user_segment(page, poff, poff + plen);
+		len -= plen;
+		ceph_msg_data_advance(cursor, plen);
+	}
+}
+
+static int prep_next_sparse_read(struct ceph_connection *con,
+				 struct ceph_msg_data_cursor *cursor)
+{
+	struct ceph_osd *o = con->private;
+	struct ceph_sparse_read *sr = &o->o_sparse_read;
+	struct ceph_osd_request *req;
+	struct ceph_osd_req_op *op;
+
+	spin_lock(&o->o_requests_lock);
+	req = lookup_request(&o->o_requests, le64_to_cpu(con->in_msg->hdr.tid));
+	if (!req) {
+		spin_unlock(&o->o_requests_lock);
+		return -EBADR;
+	}
+
+	if (o->o_sparse_op_idx < 0) {
+		dout("%s: [%d] starting new sparse read req\n",
+		     __func__, o->o_osd);
+	} else {
+		u64 end;
+
+		op = &req->r_ops[o->o_sparse_op_idx];
+
+		WARN_ON_ONCE(op->extent.sparse_ext);
+
+		/* hand back buffer we took earlier */
+		op->extent.sparse_ext = sr->sr_extent;
+		sr->sr_extent = NULL;
+		op->extent.sparse_ext_cnt = sr->sr_count;
+		sr->sr_ext_len = 0;
+		dout("%s: [%d] completed extent array len %d cursor->resid %zd\n",
+		     __func__, o->o_osd, op->extent.sparse_ext_cnt, cursor->resid);
+		/* Advance to end of data for this operation */
+		end = ceph_sparse_ext_map_end(op);
+		if (end < sr->sr_req_len)
+			advance_cursor(cursor, sr->sr_req_len - end, false);
+	}
+
+	ceph_init_sparse_read(sr);
+
+	/* find next op in this request (if any) */
+	while (++o->o_sparse_op_idx < req->r_num_ops) {
+		op = &req->r_ops[o->o_sparse_op_idx];
+		if (op->op == CEPH_OSD_OP_SPARSE_READ)
+			goto found;
+	}
+
+	/* reset for next sparse read request */
+	spin_unlock(&o->o_requests_lock);
+	o->o_sparse_op_idx = -1;
+	return 0;
+found:
+	sr->sr_req_off = op->extent.offset;
+	sr->sr_req_len = op->extent.length;
+	sr->sr_pos = sr->sr_req_off;
+	dout("%s: [%d] new sparse read op at idx %d 0x%llx~0x%llx\n", __func__,
+	     o->o_osd, o->o_sparse_op_idx, sr->sr_req_off, sr->sr_req_len);
+
+	/* hand off request's sparse extent map buffer */
+	sr->sr_ext_len = op->extent.sparse_ext_cnt;
+	op->extent.sparse_ext_cnt = 0;
+	sr->sr_extent = op->extent.sparse_ext;
+	op->extent.sparse_ext = NULL;
+
+	spin_unlock(&o->o_requests_lock);
+	return 1;
+}
+
+#ifdef __BIG_ENDIAN
+static inline void convert_extent_map(struct ceph_sparse_read *sr)
+{
+	int i;
+
+	for (i = 0; i < sr->sr_count; i++) {
+		struct ceph_sparse_extent *ext = &sr->sr_extent[i];
+
+		ext->off = le64_to_cpu((__force __le64)ext->off);
+		ext->len = le64_to_cpu((__force __le64)ext->len);
+	}
+}
+#else
+static inline void convert_extent_map(struct ceph_sparse_read *sr)
+{
+}
+#endif
+
+static int osd_sparse_read(struct ceph_connection *con,
+			   struct ceph_msg_data_cursor *cursor,
+			   char **pbuf)
+{
+	struct ceph_osd *o = con->private;
+	struct ceph_sparse_read *sr = &o->o_sparse_read;
+	u32 count = sr->sr_count;
+	u64 eoff, elen, len = 0;
+	int i, ret;
+
+	switch (sr->sr_state) {
+	case CEPH_SPARSE_READ_HDR:
+next_op:
+		ret = prep_next_sparse_read(con, cursor);
+		if (ret <= 0)
+			return ret;
+
+		/* number of extents */
+		ret = sizeof(sr->sr_count);
+		*pbuf = (char *)&sr->sr_count;
+		sr->sr_state = CEPH_SPARSE_READ_EXTENTS;
+		break;
+	case CEPH_SPARSE_READ_EXTENTS:
+		/* Convert sr_count to host-endian */
+		count = le32_to_cpu((__force __le32)sr->sr_count);
+		sr->sr_count = count;
+		dout("[%d] got %u extents\n", o->o_osd, count);
+
+		if (count > 0) {
+			if (!sr->sr_extent || count > sr->sr_ext_len) {
+				/* no extent array provided, or too short */
+				kfree(sr->sr_extent);
+				sr->sr_extent = kmalloc_array(count,
+							      sizeof(*sr->sr_extent),
+							      GFP_NOIO);
+				if (!sr->sr_extent) {
+					pr_err("%s: failed to allocate %u extents\n",
+					       __func__, count);
+					return -ENOMEM;
+				}
+				sr->sr_ext_len = count;
+			}
+			ret = count * sizeof(*sr->sr_extent);
+			*pbuf = (char *)sr->sr_extent;
+			sr->sr_state = CEPH_SPARSE_READ_DATA_LEN;
+			break;
+		}
+		/* No extents? Read data len */
+		fallthrough;
+	case CEPH_SPARSE_READ_DATA_LEN:
+		convert_extent_map(sr);
+		ret = sizeof(sr->sr_datalen);
+		*pbuf = (char *)&sr->sr_datalen;
+		sr->sr_state = CEPH_SPARSE_READ_DATA_PRE;
+		break;
+	case CEPH_SPARSE_READ_DATA_PRE:
+		/* Convert sr_datalen to host-endian */
+		sr->sr_datalen = le32_to_cpu((__force __le32)sr->sr_datalen);
+		for (i = 0; i < count; i++)
+			len += sr->sr_extent[i].len;
+		if (sr->sr_datalen != len) {
+			pr_warn_ratelimited("data len %u != extent len %llu\n",
+					    sr->sr_datalen, len);
+			return -EREMOTEIO;
+		}
+		sr->sr_state = CEPH_SPARSE_READ_DATA;
+		fallthrough;
+	case CEPH_SPARSE_READ_DATA:
+		if (sr->sr_index >= count) {
+			sr->sr_state = CEPH_SPARSE_READ_HDR;
+			goto next_op;
+		}
+
+		eoff = sr->sr_extent[sr->sr_index].off;
+		elen = sr->sr_extent[sr->sr_index].len;
+
+		dout("[%d] ext %d off 0x%llx len 0x%llx\n",
+		     o->o_osd, sr->sr_index, eoff, elen);
+
+		if (elen > INT_MAX) {
+			dout("Sparse read extent length too long (0x%llx)\n",
+			     elen);
+			return -EREMOTEIO;
+		}
+
+		/* zero out anything from sr_pos to start of extent */
+		if (sr->sr_pos < eoff)
+			advance_cursor(cursor, eoff - sr->sr_pos, true);
+
+		/* Set position to end of extent */
+		sr->sr_pos = eoff + elen;
+
+		/* send back the new length and nullify the ptr */
+		cursor->sr_resid = elen;
+		ret = elen;
+		*pbuf = NULL;
+
+		/* Bump the array index */
+		++sr->sr_index;
+		break;
+	}
+	return ret;
+}
+
 static const struct ceph_connection_operations osd_con_ops = {
 	.get = osd_get_con,
 	.put = osd_put_con,
+	.sparse_read = osd_sparse_read,
 	.alloc_msg = osd_alloc_msg,
 	.dispatch = osd_dispatch,
 	.fault = osd_fault,