rbd: support page array image requests

This patch adds the ability to build an image request whose data
will be written from or read into memory described by a page array.
(Previously only bio lists were supported.)

Originally this was going to define a new function for this purpose
but it was largely identical to the rbd_img_request_fill_bio().  So
instead, rbd_img_request_fill_bio() has been generalized to handle
both types of image request.

For the moment we still only fill image requests with bio data.

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

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 06bbd55c0ea163162663a634eb7f68a5a3fd8cfd..8a7216d784d7ed6cfb80d3d059b11a302f1f70df 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1780,6 +1780,13 @@ static bool rbd_img_obj_end_request(struct rbd_obj_request *obj_request)
                        img_request->result = result;
        }
 
+       /* Image object requests don't own their page array */
+
+       if (obj_request->type == OBJ_REQUEST_PAGES) {
+               obj_request->pages = NULL;
+               obj_request->page_count = 0;
+       }
+
        if (img_request_child_test(img_request)) {
                rbd_assert(img_request->obj_request != NULL);
                more = obj_request->which < img_request->obj_request_count - 1;
@@ -1830,30 +1837,48 @@ out:
                rbd_img_request_complete(img_request);
 }
 
-static int rbd_img_request_fill_bio(struct rbd_img_request *img_request,
-                                       struct bio *bio_list)
+/*
+ * Split up an image request into one or more object requests, each
+ * to a different object.  The "type" parameter indicates whether
+ * "data_desc" is the pointer to the head of a list of bio
+ * structures, or the base of a page array.  In either case this
+ * function assumes data_desc describes memory sufficient to hold
+ * all data described by the image request.
+ */
+static int rbd_img_request_fill(struct rbd_img_request *img_request,
+                                       enum obj_request_type type,
+                                       void *data_desc)
 {
        struct rbd_device *rbd_dev = img_request->rbd_dev;
        struct rbd_obj_request *obj_request = NULL;
        struct rbd_obj_request *next_obj_request;
        bool write_request = img_request_write_test(img_request);
-       unsigned int bio_offset;
+       struct bio *bio_list;
+       unsigned int bio_offset = 0;
+       struct page **pages;
        u64 img_offset;
        u64 resid;
        u16 opcode;
 
-       dout("%s: img %p bio %p\n", __func__, img_request, bio_list);
+       dout("%s: img %p type %d data_desc %p\n", __func__, img_request,
+               (int)type, data_desc);
 
        opcode = write_request ? CEPH_OSD_OP_WRITE : CEPH_OSD_OP_READ;
-       bio_offset = 0;
        img_offset = img_request->offset;
-       rbd_assert(img_offset == bio_list->bi_sector << SECTOR_SHIFT);
        resid = img_request->length;
        rbd_assert(resid > 0);
+
+       if (type == OBJ_REQUEST_BIO) {
+               bio_list = data_desc;
+               rbd_assert(img_offset == bio_list->bi_sector << SECTOR_SHIFT);
+       } else {
+               rbd_assert(type == OBJ_REQUEST_PAGES);
+               pages = data_desc;
+       }
+
        while (resid) {
                struct ceph_osd_request *osd_req;
                const char *object_name;
-               unsigned int clone_size;
                u64 offset;
                u64 length;
 
@@ -1863,19 +1888,33 @@ static int rbd_img_request_fill_bio(struct rbd_img_request *img_request,
                offset = rbd_segment_offset(rbd_dev, img_offset);
                length = rbd_segment_length(rbd_dev, img_offset, resid);
                obj_request = rbd_obj_request_create(object_name,
-                                               offset, length,
-                                               OBJ_REQUEST_BIO);
+                                               offset, length, type);
                kfree(object_name);     /* object request has its own copy */
                if (!obj_request)
                        goto out_unwind;
 
-               rbd_assert(length <= (u64) UINT_MAX);
-               clone_size = (unsigned int) length;
-               obj_request->bio_list = bio_chain_clone_range(&bio_list,
-                                               &bio_offset, clone_size,
-                                               GFP_ATOMIC);
-               if (!obj_request->bio_list)
-                       goto out_partial;
+               if (type == OBJ_REQUEST_BIO) {
+                       unsigned int clone_size;
+
+                       rbd_assert(length <= (u64)UINT_MAX);
+                       clone_size = (unsigned int)length;
+                       obj_request->bio_list =
+                                       bio_chain_clone_range(&bio_list,
+                                                               &bio_offset,
+                                                               clone_size,
+                                                               GFP_ATOMIC);
+                       if (!obj_request->bio_list)
+                               goto out_partial;
+               } else {
+                       unsigned int page_count;
+
+                       obj_request->pages = pages;
+                       page_count = (u32)calc_pages_for(offset, length);
+                       obj_request->page_count = page_count;
+                       if ((offset + length) & ~PAGE_MASK)
+                               page_count--;   /* more on last page */
+                       pages += page_count;
+               }
 
                osd_req = rbd_osd_req_create(rbd_dev, write_request,
                                                obj_request);
@@ -1886,8 +1925,13 @@ static int rbd_img_request_fill_bio(struct rbd_img_request *img_request,
 
                osd_req_op_extent_init(osd_req, 0, opcode, offset, length,
                                                0, 0);
-               osd_req_op_extent_osd_data_bio(osd_req, 0,
-                               obj_request->bio_list, obj_request->length);
+               if (type == OBJ_REQUEST_BIO)
+                       osd_req_op_extent_osd_data_bio(osd_req, 0,
+                                       obj_request->bio_list, length);
+               else
+                       osd_req_op_extent_osd_data_pages(osd_req, 0,
+                                       obj_request->pages, length,
+                                       offset & ~PAGE_MASK, false, false);
 
                if (write_request)
                        rbd_osd_req_format_write(obj_request);
@@ -2120,7 +2164,8 @@ static void rbd_img_parent_read(struct rbd_obj_request *obj_request)
        rbd_obj_request_get(obj_request);
        img_request->obj_request = obj_request;
 
-       result = rbd_img_request_fill_bio(img_request, obj_request->bio_list);
+       result = rbd_img_request_fill(img_request, OBJ_REQUEST_BIO,
+                                       obj_request->bio_list);
        if (result)
                goto out_err;
 
@@ -2425,7 +2470,8 @@ static void rbd_request_fn(struct request_queue *q)
 
                img_request->rq = rq;
 
-               result = rbd_img_request_fill_bio(img_request, rq->bio);
+               result = rbd_img_request_fill(img_request, OBJ_REQUEST_BIO,
+                                               rq->bio);
                if (!result)
                        result = rbd_img_request_submit(img_request);
                if (result)