xen/blk[front|back]: Squash blkif_request_rw and blkif_request_discard together
Konrad Rzeszutek Wilk [Wed, 12 Oct 2011 16:12:36 +0000 (12:12 -0400)]
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>

drivers/block/xen-blkback/blkback.c
drivers/block/xen-blkback/common.h
drivers/block/xen-blkfront.c
include/xen/interface/io/blkif.h

index 15ec4db..d7104ab 100644 (file)
@@ -362,7 +362,7 @@ static int xen_blkbk_map(struct blkif_request *req,
 {
        struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
        int i;
-       int nseg = req->nr_segments;
+       int nseg = req->u.rw.nr_segments;
        int ret = 0;
 
        /*
@@ -449,7 +449,7 @@ static void xen_blk_discard(struct xen_blkif *blkif, struct blkif_request *req)
        } else if (err)
                status = BLKIF_RSP_ERROR;
 
-       make_response(blkif, req->id, req->operation, status);
+       make_response(blkif, req->u.discard.id, req->operation, status);
 }
 
 static void xen_blk_drain_io(struct xen_blkif *blkif)
@@ -644,7 +644,8 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
        }
 
        /* Check that the number of segments is sane. */
-       nseg = req->nr_segments;
+       nseg = req->u.rw.nr_segments;
+
        if (unlikely(nseg == 0 && operation != WRITE_FLUSH &&
                                operation != REQ_DISCARD) ||
            unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
@@ -654,12 +655,12 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
                goto fail_response;
        }
 
-       preq.dev           = req->handle;
+       preq.dev           = req->u.rw.handle;
        preq.sector_number = req->u.rw.sector_number;
        preq.nr_sects      = 0;
 
        pending_req->blkif     = blkif;
-       pending_req->id        = req->id;
+       pending_req->id        = req->u.rw.id;
        pending_req->operation = req->operation;
        pending_req->status    = BLKIF_RSP_OKAY;
        pending_req->nr_pages  = nseg;
@@ -784,7 +785,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
        xen_blkbk_unmap(pending_req);
  fail_response:
        /* Haven't submitted any bio's yet. */
-       make_response(blkif, req->id, req->operation, BLKIF_RSP_ERROR);
+       make_response(blkif, req->u.rw.id, req->operation, BLKIF_RSP_ERROR);
        free_req(pending_req);
        msleep(1); /* back off a bit */
        return -EIO;
index dfb1b3a..dbfe7b3 100644 (file)
@@ -60,58 +60,66 @@ struct blkif_common_response {
        char dummy;
 };
 
-/* i386 protocol version */
-#pragma pack(push, 4)
-
 struct blkif_x86_32_request_rw {
+       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;
-};
+       uint64_t       nr_sectors;
+} __attribute__((__packed__));
 
 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  */
        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 @@ static inline void blkif_get_x86_32_req(struct blkif_request *dst,
 {
        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 @@ static inline void blkif_get_x86_64_req(struct blkif_request *dst,
 {
        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;
index 7b2ec59..2c2c4be 100644 (file)
@@ -135,15 +135,15 @@ static int get_id_from_freelist(struct blkfront_info *info)
 {
        unsigned long free = info->shadow_free;
        BUG_ON(free >= BLK_RING_SIZE);
-       info->shadow_free = info->shadow[free].req.id;
-       info->shadow[free].req.id = 0x0fffffee; /* debug */
+       info->shadow_free = info->shadow[free].req.u.rw.id;
+       info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
        return free;
 }
 
 static void add_id_to_freelist(struct blkfront_info *info,
                               unsigned long id)
 {
-       info->shadow[id].req.id  = info->shadow_free;
+       info->shadow[id].req.u.rw.id  = info->shadow_free;
        info->shadow[id].request = NULL;
        info->shadow_free = id;
 }
@@ -287,9 +287,9 @@ static int blkif_queue_request(struct request *req)
        id = get_id_from_freelist(info);
        info->shadow[id].request = req;
 
-       ring_req->id = id;
+       ring_req->u.rw.id = id;
        ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
-       ring_req->handle = info->handle;
+       ring_req->u.rw.handle = info->handle;
 
        ring_req->operation = rq_data_dir(req) ?
                BLKIF_OP_WRITE : BLKIF_OP_READ;
@@ -308,13 +308,15 @@ static int blkif_queue_request(struct request *req)
        if (unlikely(req->cmd_flags & REQ_DISCARD)) {
                /* id, sector_number and handle are set above. */
                ring_req->operation = BLKIF_OP_DISCARD;
-               ring_req->nr_segments = 0;
+               ring_req->u.discard.nr_segments = 0;
                ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
        } else {
-               ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
-               BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
+               ring_req->u.rw.nr_segments = blk_rq_map_sg(req->q, req,
+                                                          info->sg);
+               BUG_ON(ring_req->u.rw.nr_segments >
+                      BLKIF_MAX_SEGMENTS_PER_REQUEST);
 
-               for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
+               for_each_sg(info->sg, sg, ring_req->u.rw.nr_segments, i) {
                        buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
                        fsect = sg->offset >> 9;
                        lsect = fsect + (sg->length >> 9) - 1;
@@ -705,7 +707,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 static void blkif_completion(struct blk_shadow *s)
 {
        int i;
-       for (i = 0; i < s->req.nr_segments; i++)
+       for (i = 0; i < s->req.u.rw.nr_segments; i++)
                gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
 }
 
@@ -763,7 +765,7 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
                                error = -EOPNOTSUPP;
                        }
                        if (unlikely(bret->status == BLKIF_RSP_ERROR &&
-                                    info->shadow[id].req.nr_segments == 0)) {
+                                    info->shadow[id].req.u.rw.nr_segments == 0)) {
                                printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n",
                                       info->flush_op == BLKIF_OP_WRITE_BARRIER ?
                                       "barrier" :  "flush disk cache",
@@ -984,8 +986,8 @@ static int blkfront_probe(struct xenbus_device *dev,
        INIT_WORK(&info->work, blkif_restart_queue);
 
        for (i = 0; i < BLK_RING_SIZE; i++)
-               info->shadow[i].req.id = i+1;
-       info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
+               info->shadow[i].req.u.rw.id = i+1;
+       info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
 
        /* Front end dir is a number, which is used as the id. */
        info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
@@ -1019,9 +1021,9 @@ static int blkif_recover(struct blkfront_info *info)
        /* Stage 2: Set up free list. */
        memset(&info->shadow, 0, sizeof(info->shadow));
        for (i = 0; i < BLK_RING_SIZE; i++)
-               info->shadow[i].req.id = i+1;
+               info->shadow[i].req.u.rw.id = i+1;
        info->shadow_free = info->ring.req_prod_pvt;
-       info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
+       info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
 
        /* Stage 3: Find pending requests and requeue them. */
        for (i = 0; i < BLK_RING_SIZE; i++) {
@@ -1034,17 +1036,17 @@ static int blkif_recover(struct blkfront_info *info)
                *req = copy[i].req;
 
                /* We get a new request id, and must reset the shadow state. */
-               req->id = get_id_from_freelist(info);
-               memcpy(&info->shadow[req->id], &copy[i], sizeof(copy[i]));
+               req->u.rw.id = get_id_from_freelist(info);
+               memcpy(&info->shadow[req->u.rw.id], &copy[i], sizeof(copy[i]));
 
                /* Rewrite any grant references invalidated by susp/resume. */
-               for (j = 0; j < req->nr_segments; j++)
+               for (j = 0; j < req->u.rw.nr_segments; j++)
                        gnttab_grant_foreign_access_ref(
                                req->u.rw.seg[j].gref,
                                info->xbdev->otherend_id,
-                               pfn_to_mfn(info->shadow[req->id].frame[j]),
-                               rq_data_dir(info->shadow[req->id].request));
-               info->shadow[req->id].req = *req;
+                               pfn_to_mfn(info->shadow[req->u.rw.id].frame[j]),
+                               rq_data_dir(info->shadow[req->u.rw.id].request));
+               info->shadow[req->u.rw.id].req = *req;
 
                info->ring.req_prod_pvt++;
        }
index 9324488..f88e28b 100644 (file)
@@ -95,6 +95,12 @@ typedef uint64_t blkif_sector_t;
 #define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
 
 struct blkif_request_rw {
+       uint8_t        nr_segments;  /* number of segments                   */
+       blkif_vdev_t   handle;       /* only for read/write requests         */
+#ifdef CONFIG_X86_64
+       uint32_t       _pad1;        /* offsetof(blkif_request,u.rw.id) == 8 */
+#endif
+       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 {
                grant_ref_t gref;        /* reference to I/O buffer frame        */
@@ -102,23 +108,27 @@ struct blkif_request_rw {
                /* @last_sect: last sector in frame to transfer (inclusive).     */
                uint8_t     first_sect, last_sect;
        } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
-};
+} __attribute__((__packed__));
 
 struct blkif_request_discard {
+       uint8_t        nr_segments;  /* number of segments                   */
+       blkif_vdev_t   _pad1;        /* only for read/write requests         */
+#ifdef CONFIG_X86_64
+       uint32_t       _pad2;        /* offsetof(blkif_req..,u.discard.id)==8*/
+#endif
+       uint64_t       id;           /* private guest value, echoed in resp  */
        blkif_sector_t sector_number;
-       uint64_t nr_sectors;
-};
+       uint64_t       nr_sectors;
+       uint8_t        _pad3;
+} __attribute__((__packed__));
 
 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;
                struct blkif_request_discard discard;
        } u;
-};
+} __attribute__((__packed__));
 
 struct blkif_response {
        uint64_t        id;              /* copied from request */