xen/blk[front|back]: Squash blkif_request_rw and blkif_request_discard together
In a union type structure to deal with the overlapping
attributes in a easier manner.
Suggested-by: Ian Campbell <Ian.Campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index dfb1b3a..dbfe7b3 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -60,58 +60,66 @@
char dummy;
};
-/* i386 protocol version */
-#pragma pack(push, 4)
-
struct blkif_x86_32_request_rw {
- blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
- struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
-};
-
-struct blkif_x86_32_request_discard {
- blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
- uint64_t nr_sectors;
-};
-
-struct blkif_x86_32_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 */
+ blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
+ struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+} __attribute__((__packed__));
+
+struct blkif_x86_32_request_discard {
+ uint8_t nr_segments; /* number of segments */
+ blkif_vdev_t _pad1; /* was "handle" for read/write requests */
+ uint64_t id; /* private guest value, echoed in resp */
+ blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
+ uint64_t nr_sectors;
+} __attribute__((__packed__));
+
+struct blkif_x86_32_request {
+ uint8_t operation; /* BLKIF_OP_??? */
union {
struct blkif_x86_32_request_rw rw;
struct blkif_x86_32_request_discard discard;
} u;
-};
+} __attribute__((__packed__));
+
+/* i386 protocol version */
+#pragma pack(push, 4)
struct blkif_x86_32_response {
uint64_t id; /* copied from request */
uint8_t operation; /* copied from request */
int16_t status; /* BLKIF_RSP_??? */
};
#pragma pack(pop)
-
/* x86_64 protocol version */
struct blkif_x86_64_request_rw {
+ uint8_t nr_segments; /* number of segments */
+ blkif_vdev_t handle; /* only for read/write requests */
+ uint32_t _pad1; /* offsetof(blkif_reqest..,u.rw.id)==8 */
+ uint64_t id;
blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
-};
+} __attribute__((__packed__));
struct blkif_x86_64_request_discard {
+ uint8_t nr_segments; /* number of segments */
+ blkif_vdev_t _pad1; /* was "handle" for read/write requests */
+ uint32_t _pad2; /* offsetof(blkif_..,u.discard.id)==8 */
+ uint64_t id;
blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
- uint64_t nr_sectors;
-};
+ uint64_t nr_sectors;
+} __attribute__((__packed__));
struct blkif_x86_64_request {
uint8_t operation; /* BLKIF_OP_??? */
- uint8_t nr_segments; /* number of segments */
- blkif_vdev_t handle; /* only for read/write requests */
- uint64_t __attribute__((__aligned__(8))) id;
union {
struct blkif_x86_64_request_rw rw;
struct blkif_x86_64_request_discard discard;
} u;
-};
+} __attribute__((__packed__));
+
struct blkif_x86_64_response {
uint64_t __attribute__((__aligned__(8))) id;
uint8_t operation; /* copied from request */
@@ -237,18 +245,18 @@
{
int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
dst->operation = src->operation;
- dst->nr_segments = src->nr_segments;
- dst->handle = src->handle;
- dst->id = src->id;
switch (src->operation) {
case BLKIF_OP_READ:
case BLKIF_OP_WRITE:
case BLKIF_OP_WRITE_BARRIER:
case BLKIF_OP_FLUSH_DISKCACHE:
+ dst->u.rw.nr_segments = src->u.rw.nr_segments;
+ dst->u.rw.handle = src->u.rw.handle;
+ dst->u.rw.id = src->u.rw.id;
dst->u.rw.sector_number = src->u.rw.sector_number;
barrier();
- if (n > dst->nr_segments)
- n = dst->nr_segments;
+ if (n > dst->u.rw.nr_segments)
+ n = dst->u.rw.nr_segments;
for (i = 0; i < n; i++)
dst->u.rw.seg[i] = src->u.rw.seg[i];
break;
@@ -266,18 +274,18 @@
{
int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
dst->operation = src->operation;
- dst->nr_segments = src->nr_segments;
- dst->handle = src->handle;
- dst->id = src->id;
switch (src->operation) {
case BLKIF_OP_READ:
case BLKIF_OP_WRITE:
case BLKIF_OP_WRITE_BARRIER:
case BLKIF_OP_FLUSH_DISKCACHE:
+ dst->u.rw.nr_segments = src->u.rw.nr_segments;
+ dst->u.rw.handle = src->u.rw.handle;
+ dst->u.rw.id = src->u.rw.id;
dst->u.rw.sector_number = src->u.rw.sector_number;
barrier();
- if (n > dst->nr_segments)
- n = dst->nr_segments;
+ if (n > dst->u.rw.nr_segments)
+ n = dst->u.rw.nr_segments;
for (i = 0; i < n; i++)
dst->u.rw.seg[i] = src->u.rw.seg[i];
break;