[Xen-devel] [PATCH 1/2] pvops/blkif: Move read/write/barrier specific fields into a union

[<owen.smith@xxxxxxxxxx>]

From: Owen Smith <owen.smith@xxxxxxxxxx>

Patches xen.git, on branch xen/next-2.6.32

Modifies the blkif ring interface by placing the request specific
fields into a union in order to support additional operation types.

Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
---
 drivers/block/xen-blkfront.c     |    8 ++++----
 drivers/xen/blkback/blkback.c    |   16 ++++++++--------
 include/xen/blkif.h              |    8 ++++----
 include/xen/interface/io/blkif.h |   16 +++++++++++-----
 4 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 9679ffa..9ac31d2 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -286,7 +286,7 @@ static int blkif_queue_request(struct request *req)
        info->shadow[id].request = (unsigned long)req;
 
        ring_req->id = id;
-       ring_req->sector_number = (blkif_sector_t)blk_rq_pos(req);
+       ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
        ring_req->handle = info->handle;
 
        ring_req->operation = rq_data_dir(req) ?
@@ -312,7 +312,7 @@ static int blkif_queue_request(struct request *req)
                                rq_data_dir(req) );
 
                info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
-               ring_req->seg[i] =
+               ring_req->u.rw.seg[i] =
                                (struct blkif_request_segment) {
                                        .gref       = ref,
                                        .first_sect = fsect,
@@ -692,7 +692,7 @@ static void blkif_completion(struct blk_shadow *s)
 {
        int i;
        for (i = 0; i < s->req.nr_segments; i++)
-               gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL);
+               gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
 }
 
 static void
@@ -1010,7 +1010,7 @@ static int blkif_recover(struct blkfront_info *info)
                /* Rewrite any grant references invalidated by susp/resume. */
                for (j = 0; j < req->nr_segments; j++)
                        gnttab_grant_foreign_access_ref(
-                               req->seg[j].gref,
+                               req->u.rw.seg[j].gref,
                                info->xbdev->otherend_id,
                                pfn_to_mfn(info->shadow[req->id].frame[j]),
                                rq_data_dir(
diff --git a/drivers/xen/blkback/blkback.c b/drivers/xen/blkback/blkback.c
index 0bef445..b45b21f 100644
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -424,7 +424,7 @@ static void dispatch_rw_block_io(blkif_t *blkif,
        }
 
        preq.dev           = req->handle;
-       preq.sector_number = req->sector_number;
+       preq.sector_number = req->u.rw.sector_number;
        preq.nr_sects      = 0;
 
        pending_req->blkif     = blkif;
@@ -436,11 +436,11 @@ static void dispatch_rw_block_io(blkif_t *blkif,
        for (i = 0; i < nseg; i++) {
                uint32_t flags;
 
-               seg[i].nsec = req->seg[i].last_sect -
-                       req->seg[i].first_sect + 1;
+               seg[i].nsec = req->u.rw.seg[i].last_sect -
+                       req->u.rw.seg[i].first_sect + 1;
 
-               if ((req->seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
-                   (req->seg[i].last_sect < req->seg[i].first_sect))
+               if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
+                   (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect))
                        goto fail_response;
                preq.nr_sects += seg[i].nsec;
 
@@ -448,7 +448,7 @@ static void dispatch_rw_block_io(blkif_t *blkif,
                if (operation != READ)
                        flags |= GNTMAP_readonly;
                gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags,
-                                 req->seg[i].gref, blkif->domid);
+                                 req->u.rw.seg[i].gref, blkif->domid);
        }
 
        ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg);
@@ -466,11 +466,11 @@ static void dispatch_rw_block_io(blkif_t *blkif,
                        page_to_pfn(pending_page(pending_req, i)),
                        FOREIGN_FRAME(map[i].dev_bus_addr >> PAGE_SHIFT));
                seg[i].buf  = map[i].dev_bus_addr |
-                       (req->seg[i].first_sect << 9);
+                       (req->u.rw.seg[i].first_sect << 9);
                blkback_pagemap_set(vaddr_pagenr(pending_req, i),
                                    pending_page(pending_req, i),
                                    blkif->domid, req->handle,
-                                   req->seg[i].gref);
+                                   req->u.rw.seg[i].gref);
                pending_handle(pending_req, i) = map[i].handle;
        }
 
diff --git a/include/xen/blkif.h b/include/xen/blkif.h
index 7172081..71018e9 100644
--- a/include/xen/blkif.h
+++ b/include/xen/blkif.h
@@ -97,12 +97,12 @@ static void inline blkif_get_x86_32_req(struct 
blkif_request *dst, struct blkif_
        dst->nr_segments = src->nr_segments;
        dst->handle = src->handle;
        dst->id = src->id;
-       dst->sector_number = src->sector_number;
+       dst->u.rw.sector_number = src->sector_number;
        barrier();
        if (n > dst->nr_segments)
                n = dst->nr_segments;
        for (i = 0; i < n; i++)
-               dst->seg[i] = src->seg[i];
+               dst->u.rw.seg[i] = src->seg[i];
 }
 
 static void inline blkif_get_x86_64_req(struct blkif_request *dst, struct 
blkif_x86_64_request *src)
@@ -112,12 +112,12 @@ static void inline blkif_get_x86_64_req(struct 
blkif_request *dst, struct blkif_
        dst->nr_segments = src->nr_segments;
        dst->handle = src->handle;
        dst->id = src->id;
-       dst->sector_number = src->sector_number;
+       dst->u.rw.sector_number = src->sector_number;
        barrier();
        if (n > dst->nr_segments)
                n = dst->nr_segments;
        for (i = 0; i < n; i++)
-               dst->seg[i] = src->seg[i];
+               dst->u.rw.seg[i] = src->seg[i];
 }
 
 #endif /* __XEN_BLKIF_H__ */
diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
index 68dd2b4..61e523a 100644
--- a/include/xen/interface/io/blkif.h
+++ b/include/xen/interface/io/blkif.h
@@ -51,11 +51,7 @@ typedef uint64_t blkif_sector_t;
  */
 #define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
 
-struct blkif_request {
-       uint8_t        operation;    /* BLKIF_OP_???                         */
-       uint8_t        nr_segments;  /* number of segments                   */
-       blkif_vdev_t   handle;       /* only for read/write requests         */
-       uint64_t       id;           /* private guest value, echoed in resp  */
+struct blkif_request_rw {
        blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
        struct blkif_request_segment {
                grant_ref_t gref;        /* reference to I/O buffer frame       
 */
@@ -65,6 +61,16 @@ struct blkif_request {
        } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 };
 
+struct blkif_request {
+       uint8_t        operation;    /* BLKIF_OP_???                         */
+       uint8_t        nr_segments;  /* number of segments                   */
+       blkif_vdev_t   handle;       /* only for read/write requests         */
+       uint64_t       id;           /* private guest value, echoed in resp  */
+       union {
+               struct blkif_request_rw rw;
+       } u;
+};
+
 struct blkif_response {
        uint64_t        id;              /* copied from request */
        uint8_t         operation;       /* copied from request */
-- 
1.5.6.5


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