libceph: record byte count not page count

Record the byte count for an osd request rather than the page count.
The number of pages can always be derived from the byte count (and
alignment/offset) but the reverse is not true.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

drivers/block/rbd.c

@@ -1433,7 +1433,7 @@ static struct ceph_osd_request *rbd_osd_req_create(
 	case OBJ_REQUEST_PAGES:
 		osd_data->type = CEPH_OSD_DATA_TYPE_PAGES;
 		osd_data->pages = obj_request->pages;
-		osd_data->num_pages = obj_request->page_count;
+		osd_data->length = obj_request->length;
 		osd_data->alignment = offset & ~PAGE_MASK;
 		osd_data->pages_from_pool = false;
 		osd_data->own_pages = false;

fs/ceph/addr.c

@@ -238,13 +238,16 @@ static void finish_read(struct ceph_osd_request *req, struct ceph_msg *msg)
 	struct inode *inode = req->r_inode;
 	int rc = req->r_result;
 	int bytes = le32_to_cpu(msg->hdr.data_len);
+	int num_pages;
 	int i;
 
 	dout("finish_read %p req %p rc %d bytes %d\n", inode, req, rc, bytes);
 
 	/* unlock all pages, zeroing any data we didn't read */
 	BUG_ON(req->r_data_in.type != CEPH_OSD_DATA_TYPE_PAGES);
-	for (i = 0; i < req->r_data_in.num_pages; i++) {
+	num_pages = calc_pages_for((u64)req->r_data_in.alignment,
+					(u64)req->r_data_in.length);
+	for (i = 0; i < num_pages; i++) {
 		struct page *page = req->r_data_in.pages[i];
 
 		if (bytes < (int)PAGE_CACHE_SIZE) {
@@ -340,7 +343,7 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
 	}
 	req->r_data_in.type = CEPH_OSD_DATA_TYPE_PAGES;
 	req->r_data_in.pages = pages;
-	req->r_data_in.num_pages = nr_pages;
+	req->r_data_in.length = len;
 	req->r_data_in.alignment = 0;
 	req->r_callback = finish_read;
 	req->r_inode = inode;
@@ -555,6 +558,7 @@ static void writepages_finish(struct ceph_osd_request *req,
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	unsigned wrote;
 	struct page *page;
+	int num_pages;
 	int i;
 	struct ceph_snap_context *snapc = req->r_snapc;
 	struct address_space *mapping = inode->i_mapping;
@@ -565,6 +569,8 @@ static void writepages_finish(struct ceph_osd_request *req,
 	unsigned issued = ceph_caps_issued(ci);
 
 	BUG_ON(req->r_data_out.type != CEPH_OSD_DATA_TYPE_PAGES);
+	num_pages = calc_pages_for((u64)req->r_data_out.alignment,
+					(u64)req->r_data_out.length);
 	if (rc >= 0) {
 		/*
 		 * Assume we wrote the pages we originally sent.  The
@@ -572,7 +578,7 @@ static void writepages_finish(struct ceph_osd_request *req,
 		 * raced with a truncation and was adjusted at the osd,
 		 * so don't believe the reply.
 		 */
-		wrote = req->r_data_out.num_pages;
+		wrote = num_pages;
 	} else {
 		wrote = 0;
 		mapping_set_error(mapping, rc);
@@ -581,7 +587,7 @@ static void writepages_finish(struct ceph_osd_request *req,
 	     inode, rc, bytes, wrote);
 
 	/* clean all pages */
-	for (i = 0; i < req->r_data_out.num_pages; i++) {
+	for (i = 0; i < num_pages; i++) {
 		page = req->r_data_out.pages[i];
 		BUG_ON(!page);
 		WARN_ON(!PageUptodate(page));
@@ -611,9 +617,9 @@ static void writepages_finish(struct ceph_osd_request *req,
 		unlock_page(page);
 	}
 	dout("%p wrote+cleaned %d pages\n", inode, wrote);
-	ceph_put_wrbuffer_cap_refs(ci, req->r_data_out.num_pages, snapc);
+	ceph_put_wrbuffer_cap_refs(ci, num_pages, snapc);
 
-	ceph_release_pages(req->r_data_out.pages, req->r_data_out.num_pages);
+	ceph_release_pages(req->r_data_out.pages, num_pages);
 	if (req->r_data_out.pages_from_pool)
 		mempool_free(req->r_data_out.pages,
 			     ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
@@ -624,15 +630,18 @@ static void writepages_finish(struct ceph_osd_request *req,
 
 /*
  * allocate a page vec, either directly, or if necessary, via a the
- * mempool.  we avoid the mempool if we can because req->r_data_out.num_pages
+ * mempool.  we avoid the mempool if we can because req->r_data_out.length
  * may be less than the maximum write size.
  */
 static void alloc_page_vec(struct ceph_fs_client *fsc,
 			   struct ceph_osd_request *req)
 {
 	size_t size;
+	int num_pages;
 
-	size = sizeof (struct page *) * req->r_data_out.num_pages;
+	num_pages = calc_pages_for((u64)req->r_data_out.alignment,
+					(u64)req->r_data_out.length);
+	size = sizeof (struct page *) * num_pages;
 	req->r_data_out.pages = kmalloc(size, GFP_NOFS);
 	if (!req->r_data_out.pages) {
 		req->r_data_out.pages = mempool_alloc(fsc->wb_pagevec_pool,
@@ -838,11 +847,9 @@ get_more_pages:
 				}
 
 				req->r_data_out.type = CEPH_OSD_DATA_TYPE_PAGES;
-				req->r_data_out.num_pages =
-						calc_pages_for(0, len);
+				req->r_data_out.length = len;
 				req->r_data_out.alignment = 0;
-				max_pages = req->r_data_out.num_pages;
-
+				max_pages = calc_pages_for(0, (u64)len);
 				alloc_page_vec(fsc, req);
 				req->r_callback = writepages_finish;
 				req->r_inode = inode;
@@ -900,7 +907,7 @@ get_more_pages:
 		     locked_pages, offset, len);
 
 		/* revise final length, page count */
-		req->r_data_out.num_pages = locked_pages;
+		req->r_data_out.length = len;
 		req->r_request_ops[0].extent.length = cpu_to_le64(len);
 		req->r_request_ops[0].payload_len = cpu_to_le32(len);
 		req->r_request->hdr.data_len = cpu_to_le32(len);

fs/ceph/file.c

@@ -573,7 +573,7 @@ more:
 	}
 	req->r_data_out.type = CEPH_OSD_DATA_TYPE_PAGES;
 	req->r_data_out.pages = pages;
-	req->r_data_out.num_pages = num_pages;
+	req->r_data_out.length = len;
 	req->r_data_out.alignment = page_align;
 	req->r_inode = inode;
 

include/linux/ceph/osd_client.h

@@ -63,7 +63,7 @@ struct ceph_osd_data {
 	union {
 		struct {
 			struct page	**pages;
-			u32		num_pages;
+			u64		length;
 			u32		alignment;
 			bool		pages_from_pool;
 			bool		own_pages;

net/ceph/osd_client.c

@@ -107,6 +107,7 @@ static int calc_layout(struct ceph_file_layout *layout, u64 off, u64 *plen,
  */
 void ceph_osdc_release_request(struct kref *kref)
 {
+	int num_pages;
 	struct ceph_osd_request *req = container_of(kref,
 						    struct ceph_osd_request,
 						    r_kref);
@@ -124,13 +125,17 @@ void ceph_osdc_release_request(struct kref *kref)
 		ceph_msg_put(req->r_reply);
 
 	if (req->r_data_in.type == CEPH_OSD_DATA_TYPE_PAGES &&
-			req->r_data_in.own_pages)
-		ceph_release_page_vector(req->r_data_in.pages,
-					 req->r_data_in.num_pages);
+			req->r_data_in.own_pages) {
+		num_pages = calc_pages_for((u64)req->r_data_in.alignment,
+						(u64)req->r_data_in.length);
+		ceph_release_page_vector(req->r_data_in.pages, num_pages);
+	}
 	if (req->r_data_out.type == CEPH_OSD_DATA_TYPE_PAGES &&
-			req->r_data_out.own_pages)
-		ceph_release_page_vector(req->r_data_out.pages,
-					 req->r_data_out.num_pages);
+			req->r_data_out.own_pages) {
+		num_pages = calc_pages_for((u64)req->r_data_out.alignment,
+						(u64)req->r_data_out.length);
+		ceph_release_page_vector(req->r_data_out.pages, num_pages);
+	}
 
 	ceph_put_snap_context(req->r_snapc);
 	ceph_pagelist_release(&req->r_trail);
@@ -1753,8 +1758,12 @@ int ceph_osdc_start_request(struct ceph_osd_client *osdc,
 
 	osd_data = &req->r_data_out;
 	if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGES) {
+		unsigned int page_count;
+
 		req->r_request->pages = osd_data->pages;
-		req->r_request->page_count = osd_data->num_pages;
+		page_count = calc_pages_for((u64)osd_data->alignment,
+						(u64)osd_data->length);
+		req->r_request->page_count = page_count;
 		req->r_request->page_alignment = osd_data->alignment;
 #ifdef CONFIG_BLOCK
 	} else if (osd_data->type == CEPH_OSD_DATA_TYPE_BIO) {
@@ -1967,11 +1976,11 @@ int ceph_osdc_readpages(struct ceph_osd_client *osdc,
 	osd_data = &req->r_data_in;
 	osd_data->type = CEPH_OSD_DATA_TYPE_PAGES;
 	osd_data->pages = pages;
-	osd_data->num_pages = calc_pages_for(page_align, *plen);
+	osd_data->length = *plen;
 	osd_data->alignment = page_align;
 
-	dout("readpages  final extent is %llu~%llu (%d pages align %d)\n",
-	     off, *plen, osd_data->num_pages, page_align);
+	dout("readpages  final extent is %llu~%llu (%llu bytes align %d)\n",
+	     off, *plen, osd_data->length, page_align);
 
 	rc = ceph_osdc_start_request(osdc, req, false);
 	if (!rc)
@@ -2013,10 +2022,9 @@ int ceph_osdc_writepages(struct ceph_osd_client *osdc, struct ceph_vino vino,
 	osd_data = &req->r_data_out;
 	osd_data->type = CEPH_OSD_DATA_TYPE_PAGES;
 	osd_data->pages = pages;
-	osd_data->num_pages = calc_pages_for(page_align, len);
+	osd_data->length = len;
 	osd_data->alignment = page_align;
-	dout("writepages %llu~%llu (%d pages)\n", off, len,
-		osd_data->num_pages);
+	dout("writepages %llu~%llu (%llu bytes)\n", off, len, osd_data->length);
 
 	rc = ceph_osdc_start_request(osdc, req, true);
 	if (!rc)
@@ -2112,23 +2120,23 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
 		struct ceph_osd_data *osd_data = &req->r_data_in;
 
 		if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGES) {
-			int want;
+			unsigned int page_count;
 
-			want = calc_pages_for(osd_data->alignment, data_len);
 			if (osd_data->pages &&
-				unlikely(osd_data->num_pages < want)) {
+				unlikely(osd_data->length < data_len)) {
 
-				pr_warning("tid %lld reply has %d bytes %d "
-					"pages, we had only %d pages ready\n",
-					tid, data_len, want,
-					osd_data->num_pages);
+				pr_warning("tid %lld reply has %d bytes "
+					"we had only %llu bytes ready\n",
+					tid, data_len, osd_data->length);
 				*skip = 1;
 				ceph_msg_put(m);
 				m = NULL;
 				goto out;
 			}
+			page_count = calc_pages_for((u64)osd_data->alignment,
+							(u64)osd_data->length);
 			m->pages = osd_data->pages;
-			m->page_count = osd_data->num_pages;
+			m->page_count = page_count;
 			m->page_alignment = osd_data->alignment;
 #ifdef CONFIG_BLOCK
 		} else if (osd_data->type == CEPH_OSD_DATA_TYPE_BIO) {