4 files changed, 761 insertions, 38 deletions

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 5eb4898cccd4..10a41cd9c523 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -969,6 +969,62 @@ static bool ceph_msg_data_pagelist_advance(struct ceph_msg_data_cursor *cursor,
 	return true;
 }
 
+static void ceph_msg_data_iter_cursor_init(struct ceph_msg_data_cursor *cursor,
+					   size_t length)
+{
+	struct ceph_msg_data *data = cursor->data;
+
+	cursor->iov_iter = data->iter;
+	cursor->lastlen = 0;
+	iov_iter_truncate(&cursor->iov_iter, length);
+	cursor->resid = iov_iter_count(&cursor->iov_iter);
+}
+
+static struct page *ceph_msg_data_iter_next(struct ceph_msg_data_cursor *cursor,
+					    size_t *page_offset, size_t *length)
+{
+	struct page *page;
+	ssize_t len;
+
+	if (cursor->lastlen)
+		iov_iter_revert(&cursor->iov_iter, cursor->lastlen);
+
+	len = iov_iter_get_pages2(&cursor->iov_iter, &page, PAGE_SIZE,
+				  1, page_offset);
+	BUG_ON(len < 0);
+
+	cursor->lastlen = len;
+
+	/*
+	 * FIXME: The assumption is that the pages represented by the iov_iter
+	 *	  are pinned, with the references held by the upper-level
+	 *	  callers, or by virtue of being under writeback. Eventually,
+	 *	  we'll get an iov_iter_get_pages2 variant that doesn't take
+	 *	  page refs. Until then, just put the page ref.
+	 */
+	VM_BUG_ON_PAGE(!PageWriteback(page) && page_count(page) < 2, page);
+	put_page(page);
+
+	*length = min_t(size_t, len, cursor->resid);
+	return page;
+}
+
+static bool ceph_msg_data_iter_advance(struct ceph_msg_data_cursor *cursor,
+				       size_t bytes)
+{
+	BUG_ON(bytes > cursor->resid);
+	cursor->resid -= bytes;
+
+	if (bytes < cursor->lastlen) {
+		cursor->lastlen -= bytes;
+	} else {
+		iov_iter_advance(&cursor->iov_iter, bytes - cursor->lastlen);
+		cursor->lastlen = 0;
+	}
+
+	return cursor->resid;
+}
+
 /*
  * Message data is handled (sent or received) in pieces, where each
  * piece resides on a single page.  The network layer might not
@@ -996,6 +1052,9 @@ static void __ceph_msg_data_cursor_init(struct ceph_msg_data_cursor *cursor)
 	case CEPH_MSG_DATA_BVECS:
 		ceph_msg_data_bvecs_cursor_init(cursor, length);
 		break;
+	case CEPH_MSG_DATA_ITER:
+		ceph_msg_data_iter_cursor_init(cursor, length);
+		break;
 	case CEPH_MSG_DATA_NONE:
 	default:
 		/* BUG(); */
@@ -1013,6 +1072,7 @@ void ceph_msg_data_cursor_init(struct ceph_msg_data_cursor *cursor,
 
 	cursor->total_resid = length;
 	cursor->data = msg->data;
+	cursor->sr_resid = 0;
 
 	__ceph_msg_data_cursor_init(cursor);
 }
@@ -1042,6 +1102,9 @@ struct page *ceph_msg_data_next(struct ceph_msg_data_cursor *cursor,
 	case CEPH_MSG_DATA_BVECS:
 		page = ceph_msg_data_bvecs_next(cursor, page_offset, length);
 		break;
+	case CEPH_MSG_DATA_ITER:
+		page = ceph_msg_data_iter_next(cursor, page_offset, length);
+		break;
 	case CEPH_MSG_DATA_NONE:
 	default:
 		page = NULL;
@@ -1080,6 +1143,9 @@ void ceph_msg_data_advance(struct ceph_msg_data_cursor *cursor, size_t bytes)
 	case CEPH_MSG_DATA_BVECS:
 		new_piece = ceph_msg_data_bvecs_advance(cursor, bytes);
 		break;
+	case CEPH_MSG_DATA_ITER:
+		new_piece = ceph_msg_data_iter_advance(cursor, bytes);
+		break;
 	case CEPH_MSG_DATA_NONE:
 	default:
 		BUG();
@@ -1879,6 +1945,18 @@ void ceph_msg_data_add_bvecs(struct ceph_msg *msg,
 }
 EXPORT_SYMBOL(ceph_msg_data_add_bvecs);
 
+void ceph_msg_data_add_iter(struct ceph_msg *msg,
+			    struct iov_iter *iter)
+{
+	struct ceph_msg_data *data;
+
+	data = ceph_msg_data_add(msg);
+	data->type = CEPH_MSG_DATA_ITER;
+	data->iter = *iter;
+
+	msg->data_length += iov_iter_count(&data->iter);
+}
+
 /*
  * construct a new message with given type, size
  * the new msg has a ref count of 1.
diff --git a/net/ceph/messenger_v1.c b/net/ceph/messenger_v1.c
index 3d57bb48a2b4..f9a50d7f0d20 100644
--- a/net/ceph/messenger_v1.c
+++ b/net/ceph/messenger_v1.c
@@ -159,9 +159,9 @@ static size_t sizeof_footer(struct ceph_connection *con)
 
 static void prepare_message_data(struct ceph_msg *msg, u32 data_len)
 {
-	/* Initialize data cursor */
-
-	ceph_msg_data_cursor_init(&msg->cursor, msg, data_len);
+	/* Initialize data cursor if it's not a sparse read */
+	if (!msg->sparse_read)
+		ceph_msg_data_cursor_init(&msg->cursor, msg, data_len);
 }
 
 /*
@@ -960,9 +960,9 @@ static void process_ack(struct ceph_connection *con)
 	prepare_read_tag(con);
 }
 
-static int read_partial_message_section(struct ceph_connection *con,
-					struct kvec *section,
-					unsigned int sec_len, u32 *crc)
+static int read_partial_message_chunk(struct ceph_connection *con,
+				      struct kvec *section,
+				      unsigned int sec_len, u32 *crc)
 {
 	int ret, left;
 
@@ -978,11 +978,91 @@ static int read_partial_message_section(struct ceph_connection *con,
 		section->iov_len += ret;
 	}
 	if (section->iov_len == sec_len)
-		*crc = crc32c(0, section->iov_base, section->iov_len);
+		*crc = crc32c(*crc, section->iov_base, section->iov_len);
 
 	return 1;
 }
 
+static inline int read_partial_message_section(struct ceph_connection *con,
+					       struct kvec *section,
+					       unsigned int sec_len, u32 *crc)
+{
+	*crc = 0;
+	return read_partial_message_chunk(con, section, sec_len, crc);
+}
+
+static int read_sparse_msg_extent(struct ceph_connection *con, u32 *crc)
+{
+	struct ceph_msg_data_cursor *cursor = &con->in_msg->cursor;
+	bool do_bounce = ceph_test_opt(from_msgr(con->msgr), RXBOUNCE);
+
+	if (do_bounce && unlikely(!con->bounce_page)) {
+		con->bounce_page = alloc_page(GFP_NOIO);
+		if (!con->bounce_page) {
+			pr_err("failed to allocate bounce page\n");
+			return -ENOMEM;
+		}
+	}
+
+	while (cursor->sr_resid > 0) {
+		struct page *page, *rpage;
+		size_t off, len;
+		int ret;
+
+		page = ceph_msg_data_next(cursor, &off, &len);
+		rpage = do_bounce ? con->bounce_page : page;
+
+		/* clamp to what remains in extent */
+		len = min_t(int, len, cursor->sr_resid);
+		ret = ceph_tcp_recvpage(con->sock, rpage, (int)off, len);
+		if (ret <= 0)
+			return ret;
+		*crc = ceph_crc32c_page(*crc, rpage, off, ret);
+		ceph_msg_data_advance(cursor, (size_t)ret);
+		cursor->sr_resid -= ret;
+		if (do_bounce)
+			memcpy_page(page, off, rpage, off, ret);
+	}
+	return 1;
+}
+
+static int read_sparse_msg_data(struct ceph_connection *con)
+{
+	struct ceph_msg_data_cursor *cursor = &con->in_msg->cursor;
+	bool do_datacrc = !ceph_test_opt(from_msgr(con->msgr), NOCRC);
+	u32 crc = 0;
+	int ret = 1;
+
+	if (do_datacrc)
+		crc = con->in_data_crc;
+
+	do {
+		if (con->v1.in_sr_kvec.iov_base)
+			ret = read_partial_message_chunk(con,
+							 &con->v1.in_sr_kvec,
+							 con->v1.in_sr_len,
+							 &crc);
+		else if (cursor->sr_resid > 0)
+			ret = read_sparse_msg_extent(con, &crc);
+
+		if (ret <= 0) {
+			if (do_datacrc)
+				con->in_data_crc = crc;
+			return ret;
+		}
+
+		memset(&con->v1.in_sr_kvec, 0, sizeof(con->v1.in_sr_kvec));
+		ret = con->ops->sparse_read(con, cursor,
+				(char **)&con->v1.in_sr_kvec.iov_base);
+		con->v1.in_sr_len = ret;
+	} while (ret > 0);
+
+	if (do_datacrc)
+		con->in_data_crc = crc;
+
+	return ret < 0 ? ret : 1;  /* must return > 0 to indicate success */
+}
+
 static int read_partial_msg_data(struct ceph_connection *con)
 {
 	struct ceph_msg_data_cursor *cursor = &con->in_msg->cursor;
@@ -1173,7 +1253,9 @@ static int read_partial_message(struct ceph_connection *con)
 		if (!m->num_data_items)
 			return -EIO;
 
-		if (ceph_test_opt(from_msgr(con->msgr), RXBOUNCE))
+		if (m->sparse_read)
+			ret = read_sparse_msg_data(con);
+		else if (ceph_test_opt(from_msgr(con->msgr), RXBOUNCE))
 			ret = read_partial_msg_data_bounce(con);
 		else
 			ret = read_partial_msg_data(con);
diff --git a/net/ceph/messenger_v2.c b/net/ceph/messenger_v2.c
index 1df1d29dee92..d09a39ff2cf0 100644
--- a/net/ceph/messenger_v2.c
+++ b/net/ceph/messenger_v2.c
@@ -8,9 +8,9 @@
 #include <linux/ceph/ceph_debug.h>
 
 #include <crypto/aead.h>
-#include <crypto/algapi.h>  /* for crypto_memneq() */
 #include <crypto/hash.h>
 #include <crypto/sha2.h>
+#include <crypto/utils.h>
 #include <linux/bvec.h>
 #include <linux/crc32c.h>
 #include <linux/net.h>
@@ -52,14 +52,16 @@
 #define FRAME_LATE_STATUS_COMPLETE	0xe
 #define FRAME_LATE_STATUS_ABORTED_MASK	0xf
 
-#define IN_S_HANDLE_PREAMBLE		1
-#define IN_S_HANDLE_CONTROL		2
-#define IN_S_HANDLE_CONTROL_REMAINDER	3
-#define IN_S_PREPARE_READ_DATA		4
-#define IN_S_PREPARE_READ_DATA_CONT	5
-#define IN_S_PREPARE_READ_ENC_PAGE	6
-#define IN_S_HANDLE_EPILOGUE		7
-#define IN_S_FINISH_SKIP		8
+#define IN_S_HANDLE_PREAMBLE			1
+#define IN_S_HANDLE_CONTROL			2
+#define IN_S_HANDLE_CONTROL_REMAINDER		3
+#define IN_S_PREPARE_READ_DATA			4
+#define IN_S_PREPARE_READ_DATA_CONT		5
+#define IN_S_PREPARE_READ_ENC_PAGE		6
+#define IN_S_PREPARE_SPARSE_DATA		7
+#define IN_S_PREPARE_SPARSE_DATA_CONT		8
+#define IN_S_HANDLE_EPILOGUE			9
+#define IN_S_FINISH_SKIP			10
 
 #define OUT_S_QUEUE_DATA		1
 #define OUT_S_QUEUE_DATA_CONT		2
@@ -967,12 +969,48 @@ static void init_sgs_cursor(struct scatterlist **sg,
 	}
 }
 
+/**
+ * init_sgs_pages: set up scatterlist on an array of page pointers
+ * @sg:		scatterlist to populate
+ * @pages:	pointer to page array
+ * @dpos:	position in the array to start (bytes)
+ * @dlen:	len to add to sg (bytes)
+ * @pad:	pointer to pad destination (if any)
+ *
+ * Populate the scatterlist from the page array, starting at an arbitrary
+ * byte in the array and running for a specified length.
+ */
+static void init_sgs_pages(struct scatterlist **sg, struct page **pages,
+			   int dpos, int dlen, u8 *pad)
+{
+	int idx = dpos >> PAGE_SHIFT;
+	int off = offset_in_page(dpos);
+	int resid = dlen;
+
+	do {
+		int len = min(resid, (int)PAGE_SIZE - off);
+
+		sg_set_page(*sg, pages[idx], len, off);
+		*sg = sg_next(*sg);
+		off = 0;
+		++idx;
+		resid -= len;
+	} while (resid);
+
+	if (need_padding(dlen)) {
+		sg_set_buf(*sg, pad, padding_len(dlen));
+		*sg = sg_next(*sg);
+	}
+}
+
 static int setup_message_sgs(struct sg_table *sgt, struct ceph_msg *msg,
 			     u8 *front_pad, u8 *middle_pad, u8 *data_pad,
-			     void *epilogue, bool add_tag)
+			     void *epilogue, struct page **pages, int dpos,
+			     bool add_tag)
 {
 	struct ceph_msg_data_cursor cursor;
 	struct scatterlist *cur_sg;
+	int dlen = data_len(msg);
 	int sg_cnt;
 	int ret;
 
@@ -986,9 +1024,15 @@ static int setup_message_sgs(struct sg_table *sgt, struct ceph_msg *msg,
 	if (middle_len(msg))
 		sg_cnt += calc_sg_cnt(msg->middle->vec.iov_base,
 				      middle_len(msg));
-	if (data_len(msg)) {
-		ceph_msg_data_cursor_init(&cursor, msg, data_len(msg));
-		sg_cnt += calc_sg_cnt_cursor(&cursor);
+	if (dlen) {
+		if (pages) {
+			sg_cnt += calc_pages_for(dpos, dlen);
+			if (need_padding(dlen))
+				sg_cnt++;
+		} else {
+			ceph_msg_data_cursor_init(&cursor, msg, dlen);
+			sg_cnt += calc_sg_cnt_cursor(&cursor);
+		}
 	}
 
 	ret = sg_alloc_table(sgt, sg_cnt, GFP_NOIO);
@@ -1002,9 +1046,13 @@ static int setup_message_sgs(struct sg_table *sgt, struct ceph_msg *msg,
 	if (middle_len(msg))
 		init_sgs(&cur_sg, msg->middle->vec.iov_base, middle_len(msg),
 			 middle_pad);
-	if (data_len(msg)) {
-		ceph_msg_data_cursor_init(&cursor, msg, data_len(msg));
-		init_sgs_cursor(&cur_sg, &cursor, data_pad);
+	if (dlen) {
+		if (pages) {
+			init_sgs_pages(&cur_sg, pages, dpos, dlen, data_pad);
+		} else {
+			ceph_msg_data_cursor_init(&cursor, msg, dlen);
+			init_sgs_cursor(&cur_sg, &cursor, data_pad);
+		}
 	}
 
 	WARN_ON(!sg_is_last(cur_sg));
@@ -1039,10 +1087,53 @@ static int decrypt_control_remainder(struct ceph_connection *con)
 			 padded_len(rem_len) + CEPH_GCM_TAG_LEN);
 }
 
+/* Process sparse read data that lives in a buffer */
+static int process_v2_sparse_read(struct ceph_connection *con,
+				  struct page **pages, int spos)
+{
+	struct ceph_msg_data_cursor *cursor = &con->v2.in_cursor;
+	int ret;
+
+	for (;;) {
+		char *buf = NULL;
+
+		ret = con->ops->sparse_read(con, cursor, &buf);
+		if (ret <= 0)
+			return ret;
+
+		dout("%s: sparse_read return %x buf %p\n", __func__, ret, buf);
+
+		do {
+			int idx = spos >> PAGE_SHIFT;
+			int soff = offset_in_page(spos);
+			struct page *spage = con->v2.in_enc_pages[idx];
+			int len = min_t(int, ret, PAGE_SIZE - soff);
+
+			if (buf) {
+				memcpy_from_page(buf, spage, soff, len);
+				buf += len;
+			} else {
+				struct bio_vec bv;
+
+				get_bvec_at(cursor, &bv);
+				len = min_t(int, len, bv.bv_len);
+				memcpy_page(bv.bv_page, bv.bv_offset,
+					    spage, soff, len);
+				ceph_msg_data_advance(cursor, len);
+			}
+			spos += len;
+			ret -= len;
+		} while (ret);
+	}
+}
+
 static int decrypt_tail(struct ceph_connection *con)
 {
 	struct sg_table enc_sgt = {};
 	struct sg_table sgt = {};
+	struct page **pages = NULL;
+	bool sparse = con->in_msg->sparse_read;
+	int dpos = 0;
 	int tail_len;
 	int ret;
 
@@ -1053,9 +1144,14 @@ static int decrypt_tail(struct ceph_connection *con)
 	if (ret)
 		goto out;
 
+	if (sparse) {
+		dpos = padded_len(front_len(con->in_msg) + padded_len(middle_len(con->in_msg)));
+		pages = con->v2.in_enc_pages;
+	}
+
 	ret = setup_message_sgs(&sgt, con->in_msg, FRONT_PAD(con->v2.in_buf),
-			MIDDLE_PAD(con->v2.in_buf), DATA_PAD(con->v2.in_buf),
-			con->v2.in_buf, true);
+				MIDDLE_PAD(con->v2.in_buf), DATA_PAD(con->v2.in_buf),
+				con->v2.in_buf, pages, dpos, true);
 	if (ret)
 		goto out;
 
@@ -1065,6 +1161,12 @@ static int decrypt_tail(struct ceph_connection *con)
 	if (ret)
 		goto out;
 
+	if (sparse && data_len(con->in_msg)) {
+		ret = process_v2_sparse_read(con, con->v2.in_enc_pages, dpos);
+		if (ret)
+			goto out;
+	}
+
 	WARN_ON(!con->v2.in_enc_page_cnt);
 	ceph_release_page_vector(con->v2.in_enc_pages,
 				 con->v2.in_enc_page_cnt);
@@ -1588,7 +1690,7 @@ static int prepare_message_secure(struct ceph_connection *con)
 
 	encode_epilogue_secure(con, false);
 	ret = setup_message_sgs(&sgt, con->out_msg, zerop, zerop, zerop,
-				&con->v2.out_epil, false);
+				&con->v2.out_epil, NULL, 0, false);
 	if (ret)
 		goto out;
 
@@ -1825,6 +1927,123 @@ static void prepare_read_data_cont(struct ceph_connection *con)
 	con->v2.in_state = IN_S_HANDLE_EPILOGUE;
 }
 
+static int prepare_sparse_read_cont(struct ceph_connection *con)
+{
+	int ret;
+	struct bio_vec bv;
+	char *buf = NULL;
+	struct ceph_msg_data_cursor *cursor = &con->v2.in_cursor;
+
+	WARN_ON(con->v2.in_state != IN_S_PREPARE_SPARSE_DATA_CONT);
+
+	if (iov_iter_is_bvec(&con->v2.in_iter)) {
+		if (ceph_test_opt(from_msgr(con->msgr), RXBOUNCE)) {
+			con->in_data_crc = crc32c(con->in_data_crc,
+						  page_address(con->bounce_page),
+						  con->v2.in_bvec.bv_len);
+			get_bvec_at(cursor, &bv);
+			memcpy_to_page(bv.bv_page, bv.bv_offset,
+				       page_address(con->bounce_page),
+				       con->v2.in_bvec.bv_len);
+		} else {
+			con->in_data_crc = ceph_crc32c_page(con->in_data_crc,
+							    con->v2.in_bvec.bv_page,
+							    con->v2.in_bvec.bv_offset,
+							    con->v2.in_bvec.bv_len);
+		}
+
+		ceph_msg_data_advance(cursor, con->v2.in_bvec.bv_len);
+		cursor->sr_resid -= con->v2.in_bvec.bv_len;
+		dout("%s: advance by 0x%x sr_resid 0x%x\n", __func__,
+		     con->v2.in_bvec.bv_len, cursor->sr_resid);
+		WARN_ON_ONCE(cursor->sr_resid > cursor->total_resid);
+		if (cursor->sr_resid) {
+			get_bvec_at(cursor, &bv);
+			if (bv.bv_len > cursor->sr_resid)
+				bv.bv_len = cursor->sr_resid;
+			if (ceph_test_opt(from_msgr(con->msgr), RXBOUNCE)) {
+				bv.bv_page = con->bounce_page;
+				bv.bv_offset = 0;
+			}
+			set_in_bvec(con, &bv);
+			con->v2.data_len_remain -= bv.bv_len;
+			return 0;
+		}
+	} else if (iov_iter_is_kvec(&con->v2.in_iter)) {
+		/* On first call, we have no kvec so don't compute crc */
+		if (con->v2.in_kvec_cnt) {
+			WARN_ON_ONCE(con->v2.in_kvec_cnt > 1);
+			con->in_data_crc = crc32c(con->in_data_crc,
+						  con->v2.in_kvecs[0].iov_base,
+						  con->v2.in_kvecs[0].iov_len);
+		}
+	} else {
+		return -EIO;
+	}
+
+	/* get next extent */
+	ret = con->ops->sparse_read(con, cursor, &buf);
+	if (ret <= 0) {
+		if (ret < 0)
+			return ret;
+
+		reset_in_kvecs(con);
+		add_in_kvec(con, con->v2.in_buf, CEPH_EPILOGUE_PLAIN_LEN);
+		con->v2.in_state = IN_S_HANDLE_EPILOGUE;
+		return 0;
+	}
+
+	if (buf) {
+		/* receive into buffer */
+		reset_in_kvecs(con);
+		add_in_kvec(con, buf, ret);
+		con->v2.data_len_remain -= ret;
+		return 0;
+	}
+
+	if (ret > cursor->total_resid) {
+		pr_warn("%s: ret 0x%x total_resid 0x%zx resid 0x%zx\n",
+			__func__, ret, cursor->total_resid, cursor->resid);
+		return -EIO;
+	}
+	get_bvec_at(cursor, &bv);
+	if (bv.bv_len > cursor->sr_resid)
+		bv.bv_len = cursor->sr_resid;
+	if (ceph_test_opt(from_msgr(con->msgr), RXBOUNCE)) {
+		if (unlikely(!con->bounce_page)) {
+			con->bounce_page = alloc_page(GFP_NOIO);
+			if (!con->bounce_page) {
+				pr_err("failed to allocate bounce page\n");
+				return -ENOMEM;
+			}
+		}
+
+		bv.bv_page = con->bounce_page;
+		bv.bv_offset = 0;
+	}
+	set_in_bvec(con, &bv);
+	con->v2.data_len_remain -= ret;
+	return ret;
+}
+
+static int prepare_sparse_read_data(struct ceph_connection *con)
+{
+	struct ceph_msg *msg = con->in_msg;
+
+	dout("%s: starting sparse read\n", __func__);
+
+	if (WARN_ON_ONCE(!con->ops->sparse_read))
+		return -EOPNOTSUPP;
+
+	if (!con_secure(con))
+		con->in_data_crc = -1;
+
+	reset_in_kvecs(con);
+	con->v2.in_state = IN_S_PREPARE_SPARSE_DATA_CONT;
+	con->v2.data_len_remain = data_len(msg);
+	return prepare_sparse_read_cont(con);
+}
+
 static int prepare_read_tail_plain(struct ceph_connection *con)
 {
 	struct ceph_msg *msg = con->in_msg;
@@ -1845,7 +2064,10 @@ static int prepare_read_tail_plain(struct ceph_connection *con)
 	}
 
 	if (data_len(msg)) {
-		con->v2.in_state = IN_S_PREPARE_READ_DATA;
+		if (msg->sparse_read)
+			con->v2.in_state = IN_S_PREPARE_SPARSE_DATA;
+		else
+			con->v2.in_state = IN_S_PREPARE_READ_DATA;
 	} else {
 		add_in_kvec(con, con->v2.in_buf, CEPH_EPILOGUE_PLAIN_LEN);
 		con->v2.in_state = IN_S_HANDLE_EPILOGUE;
@@ -2898,6 +3120,12 @@ static int populate_in_iter(struct ceph_connection *con)
 			prepare_read_enc_page(con);
 			ret = 0;
 			break;
+		case IN_S_PREPARE_SPARSE_DATA:
+			ret = prepare_sparse_read_data(con);
+			break;
+		case IN_S_PREPARE_SPARSE_DATA_CONT:
+			ret = prepare_sparse_read_cont(con);
+			break;
 		case IN_S_HANDLE_EPILOGUE:
 			ret = handle_epilogue(con);
 			break;
@@ -3489,6 +3717,23 @@ static void revoke_at_prepare_read_enc_page(struct ceph_connection *con)
 	con->v2.in_state = IN_S_FINISH_SKIP;
 }
 
+static void revoke_at_prepare_sparse_data(struct ceph_connection *con)
+{
+	int resid;  /* current piece of data */
+	int remaining;
+
+	WARN_ON(con_secure(con));
+	WARN_ON(!data_len(con->in_msg));
+	WARN_ON(!iov_iter_is_bvec(&con->v2.in_iter));
+	resid = iov_iter_count(&con->v2.in_iter);
+	dout("%s con %p resid %d\n", __func__, con, resid);
+
+	remaining = CEPH_EPILOGUE_PLAIN_LEN + con->v2.data_len_remain;
+	con->v2.in_iter.count -= resid;
+	set_in_skip(con, resid + remaining);
+	con->v2.in_state = IN_S_FINISH_SKIP;
+}
+
 static void revoke_at_handle_epilogue(struct ceph_connection *con)
 {
 	int resid;
@@ -3505,6 +3750,7 @@ static void revoke_at_handle_epilogue(struct ceph_connection *con)
 void ceph_con_v2_revoke_incoming(struct ceph_connection *con)
 {
 	switch (con->v2.in_state) {
+	case IN_S_PREPARE_SPARSE_DATA:
 	case IN_S_PREPARE_READ_DATA:
 		revoke_at_prepare_read_data(con);
 		break;
@@ -3514,6 +3760,9 @@ void ceph_con_v2_revoke_incoming(struct ceph_connection *con)
 	case IN_S_PREPARE_READ_ENC_PAGE:
 		revoke_at_prepare_read_enc_page(con);
 		break;
+	case IN_S_PREPARE_SPARSE_DATA_CONT:
+		revoke_at_prepare_sparse_data(con);
+		break;
 	case IN_S_HANDLE_EPILOGUE:
 		revoke_at_handle_epilogue(con);
 		break;
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 658a6f2320cf..d3a759e052c8 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)
 {
@@ -264,6 +271,22 @@ 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);
 
+/**
+ * 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, extent, osd_data);
+	ceph_osd_iter_init(osd_data, iter);
+}
+EXPORT_SYMBOL(osd_req_op_extent_osd_iter);
+
 static void osd_req_op_cls_request_info_pagelist(
 			struct ceph_osd_request *osd_req,
 			unsigned int which, struct ceph_pagelist *pagelist)
@@ -346,6 +369,8 @@ 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 +401,10 @@ 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 +696,7 @@ 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 +766,7 @@ 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 +979,8 @@ 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 +993,7 @@ 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 +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));
@@ -1059,7 +1094,8 @@ 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 +1136,30 @@ 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 +1171,18 @@ fail:
 }
 EXPORT_SYMBOL(ceph_osdc_new_request);
 
+int __ceph_alloc_sparse_ext_map(struct ceph_osd_req_op *op, int cnt)
+{
+	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 +1240,7 @@ 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 +1251,13 @@ 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 +1268,8 @@ 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 +1289,9 @@ 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 +1482,9 @@ 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 +1496,9 @@ 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 +2096,7 @@ 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 +2516,10 @@ 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);
 
 	/*
@@ -3795,6 +3878,7 @@ 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);
@@ -5348,6 +5432,24 @@ 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
@@ -5364,6 +5466,7 @@ 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)) {
@@ -5396,7 +5499,8 @@ 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);
@@ -5406,6 +5510,8 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
 	}
 
 	m = ceph_msg_get(req->r_reply);
+	m->sparse_read = (bool)srlen;
+
 	dout("get_reply tid %lld %p\n", tid, m);
 
 out_unlock_session:
@@ -5638,9 +5744,217 @@ 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) {
+		u64 srlen = sparse_data_requested(req);
+
+		dout("%s: [%d] starting new sparse read req. srlen=0x%llx\n",
+		     __func__, o->o_osd, srlen);
+		ceph_msg_data_cursor_init(cursor, con->in_msg, srlen);
+	} 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
+
+#define MAX_EXTENTS 4096
+
+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;
+	int 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) {
+				/*
+				 * Apply a hard cap to the number of extents.
+				 * If we have more, assume something is wrong.
+				 */
+				if (count > MAX_EXTENTS) {
+					dout("%s: OSD returned 0x%x extents in a single reply!\n",
+					     __func__, count);
+					return -EREMOTEIO;
+				}
+
+				/* 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)
+					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;
+		break;
+	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,