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[Xen-devel] [PATCH v3 4/9] xen/blkfront: pseudo support for multi hardware queues/rings



Prepare patch for multi hardware queues/rings, the ring number was set to 1 by
force.

* Use 'nr_rings' in per dev_info to identify how many hw queues/rings are
  supported, and a pointer *rinfo for all its rings.
* Rename 'nr_ring_pages' => 'pages_per_ring' to distinguish from 'nr_rings'
  better.

Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
 drivers/block/xen-blkfront.c |  513 +++++++++++++++++++++++++-----------------
 1 file changed, 308 insertions(+), 205 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index bf416d5..bf45c99 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -107,7 +107,7 @@ static unsigned int xen_blkif_max_ring_order;
 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 
S_IRUGO);
 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for 
the shared ring");
 
-#define BLK_RING_SIZE(dinfo) __CONST_RING_SIZE(blkif, PAGE_SIZE * 
(dinfo)->nr_ring_pages)
+#define BLK_RING_SIZE(dinfo) __CONST_RING_SIZE(blkif, PAGE_SIZE * 
(dinfo)->pages_per_ring)
 #define BLK_MAX_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE * 
XENBUS_MAX_RING_PAGES)
 /*
  * ring-ref%i i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
@@ -157,9 +157,10 @@ struct blkfront_dev_info {
        unsigned int feature_persistent:1;
        unsigned int max_indirect_segments;
        int is_ready;
-       unsigned int nr_ring_pages;
+       unsigned int pages_per_ring;
        struct blk_mq_tag_set tag_set;
-       struct blkfront_ring_info rinfo;
+       struct blkfront_ring_info *rinfo;
+       unsigned int nr_rings;
 };
 
 static unsigned int nr_minors;
@@ -191,7 +192,7 @@ static DEFINE_SPINLOCK(minor_lock);
        ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
 
 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
-static int blkfront_gather_backend_features(struct blkfront_dev_info *dinfo);
+static void __blkfront_gather_backend_features(struct blkfront_dev_info 
*dinfo);
 
 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 {
@@ -668,7 +669,7 @@ static int blk_mq_init_hctx(struct blk_mq_hw_ctx *hctx, 
void *data,
 {
        struct blkfront_dev_info *dinfo = (struct blkfront_dev_info *)data;
 
-       hctx->driver_data = &dinfo->rinfo;
+       hctx->driver_data = &dinfo->rinfo[index];
        return 0;
 }
 
@@ -927,8 +928,8 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 
 static void xlvbd_release_gendisk(struct blkfront_dev_info *dinfo)
 {
-       unsigned int minor, nr_minors;
-       struct blkfront_ring_info *rinfo = &dinfo->rinfo;
+       unsigned int minor, nr_minors, i;
+       struct blkfront_ring_info *rinfo;
 
        if (dinfo->rq == NULL)
                return;
@@ -936,11 +937,15 @@ static void xlvbd_release_gendisk(struct 
blkfront_dev_info *dinfo)
        /* No more blkif_request(). */
        blk_mq_stop_hw_queues(dinfo->rq);
 
-       /* No more gnttab callback work. */
-       gnttab_cancel_free_callback(&rinfo->callback);
+       for (i = 0; i < dinfo->nr_rings; i++) {
+               rinfo = &dinfo->rinfo[i];
 
-       /* Flush gnttab callback work. Must be done with no locks held. */
-       flush_work(&rinfo->work);
+               /* No more gnttab callback work. */
+               gnttab_cancel_free_callback(&rinfo->callback);
+
+               /* Flush gnttab callback work. Must be done with no locks held. 
*/
+               flush_work(&rinfo->work);
+       }
 
        del_gendisk(dinfo->gd);
 
@@ -977,8 +982,8 @@ static void blkif_free(struct blkfront_dev_info *dinfo, int 
suspend)
 {
        struct grant *persistent_gnt;
        struct grant *n;
-       int i, j, segs;
-       struct blkfront_ring_info *rinfo = &dinfo->rinfo;
+       int i, j, segs, r_index;
+       struct blkfront_ring_info *rinfo;
 
        /* Prevent new requests being issued until we fix things up. */
        spin_lock_irq(&dinfo->io_lock);
@@ -988,100 +993,103 @@ static void blkif_free(struct blkfront_dev_info *dinfo, 
int suspend)
        if (dinfo->rq)
                blk_mq_stop_hw_queues(dinfo->rq);
 
-       /* Remove all persistent grants */
-       if (!list_empty(&rinfo->grants)) {
-               list_for_each_entry_safe(persistent_gnt, n,
-                                        &rinfo->grants, node) {
-                       list_del(&persistent_gnt->node);
-                       if (persistent_gnt->gref != GRANT_INVALID_REF) {
-                               gnttab_end_foreign_access(persistent_gnt->gref,
-                                                         0, 0UL);
-                               rinfo->persistent_gnts_c--;
+       for (r_index = 0; r_index < dinfo->nr_rings; r_index++) {
+               rinfo = &dinfo->rinfo[r_index];
+
+               /* Remove all persistent grants */
+               if (!list_empty(&rinfo->grants)) {
+                       list_for_each_entry_safe(persistent_gnt, n,
+                                                &rinfo->grants, node) {
+                               list_del(&persistent_gnt->node);
+                               if (persistent_gnt->gref != GRANT_INVALID_REF) {
+                                       
gnttab_end_foreign_access(persistent_gnt->gref,
+                                                                 0, 0UL);
+                                       rinfo->persistent_gnts_c--;
+                               }
+                               if (dinfo->feature_persistent)
+                                       
__free_page(pfn_to_page(persistent_gnt->pfn));
+                               kfree(persistent_gnt);
                        }
-                       if (dinfo->feature_persistent)
-                               __free_page(pfn_to_page(persistent_gnt->pfn));
-                       kfree(persistent_gnt);
                }
-       }
-       BUG_ON(rinfo->persistent_gnts_c != 0);
+               BUG_ON(rinfo->persistent_gnts_c != 0);
 
-       /*
-        * Remove indirect pages, this only happens when using indirect
-        * descriptors but not persistent grants
-        */
-       if (!list_empty(&rinfo->indirect_pages)) {
-               struct page *indirect_page, *n;
-
-               BUG_ON(dinfo->feature_persistent);
-               list_for_each_entry_safe(indirect_page, n, 
&rinfo->indirect_pages, lru) {
-                       list_del(&indirect_page->lru);
-                       __free_page(indirect_page);
-               }
-       }
-
-       for (i = 0; i < BLK_RING_SIZE(dinfo); i++) {
                /*
-                * Clear persistent grants present in requests already
-                * on the shared ring
+                * Remove indirect pages, this only happens when using indirect
+                * descriptors but not persistent grants
                 */
-               if (!rinfo->shadow[i].request)
-                       goto free_shadow;
-
-               segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
-                      rinfo->shadow[i].req.u.indirect.nr_segments :
-                      rinfo->shadow[i].req.u.rw.nr_segments;
-               for (j = 0; j < segs; j++) {
-                       persistent_gnt = rinfo->shadow[i].grants_used[j];
-                       gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
-                       if (dinfo->feature_persistent)
-                               __free_page(pfn_to_page(persistent_gnt->pfn));
-                       kfree(persistent_gnt);
+               if (!list_empty(&rinfo->indirect_pages)) {
+                       struct page *indirect_page, *n;
+
+                       BUG_ON(dinfo->feature_persistent);
+                       list_for_each_entry_safe(indirect_page, n, 
&rinfo->indirect_pages, lru) {
+                               list_del(&indirect_page->lru);
+                               __free_page(indirect_page);
+                       }
                }
 
-               if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
+               for (i = 0; i < BLK_RING_SIZE(dinfo); i++) {
                        /*
-                        * If this is not an indirect operation don't try to
-                        * free indirect segments
+                        * Clear persistent grants present in requests already
+                        * on the shared ring
                         */
-                       goto free_shadow;
+                       if (!rinfo->shadow[i].request)
+                               goto free_shadow;
+
+                       segs = rinfo->shadow[i].req.operation == 
BLKIF_OP_INDIRECT ?
+                              rinfo->shadow[i].req.u.indirect.nr_segments :
+                              rinfo->shadow[i].req.u.rw.nr_segments;
+                       for (j = 0; j < segs; j++) {
+                               persistent_gnt = 
rinfo->shadow[i].grants_used[j];
+                               gnttab_end_foreign_access(persistent_gnt->gref, 
0, 0UL);
+                               if (dinfo->feature_persistent)
+                                       
__free_page(pfn_to_page(persistent_gnt->pfn));
+                               kfree(persistent_gnt);
+                       }
 
-               for (j = 0; j < INDIRECT_GREFS(segs); j++) {
-                       persistent_gnt = rinfo->shadow[i].indirect_grants[j];
-                       gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
-                       __free_page(pfn_to_page(persistent_gnt->pfn));
-                       kfree(persistent_gnt);
-               }
+                       if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
+                               /*
+                                * If this is not an indirect operation don't 
try to
+                                * free indirect segments
+                                */
+                               goto free_shadow;
+
+                       for (j = 0; j < INDIRECT_GREFS(segs); j++) {
+                               persistent_gnt = 
rinfo->shadow[i].indirect_grants[j];
+                               gnttab_end_foreign_access(persistent_gnt->gref, 
0, 0UL);
+                               __free_page(pfn_to_page(persistent_gnt->pfn));
+                               kfree(persistent_gnt);
+                       }
 
 free_shadow:
-               kfree(rinfo->shadow[i].grants_used);
-               rinfo->shadow[i].grants_used = NULL;
-               kfree(rinfo->shadow[i].indirect_grants);
-               rinfo->shadow[i].indirect_grants = NULL;
-               kfree(rinfo->shadow[i].sg);
-               rinfo->shadow[i].sg = NULL;
-       }
+                       kfree(rinfo->shadow[i].grants_used);
+                       rinfo->shadow[i].grants_used = NULL;
+                       kfree(rinfo->shadow[i].indirect_grants);
+                       rinfo->shadow[i].indirect_grants = NULL;
+                       kfree(rinfo->shadow[i].sg);
+                       rinfo->shadow[i].sg = NULL;
+               }
 
-       /* No more gnttab callback work. */
-       gnttab_cancel_free_callback(&rinfo->callback);
-       spin_unlock_irq(&dinfo->io_lock);
+               /* No more gnttab callback work. */
+               gnttab_cancel_free_callback(&rinfo->callback);
+               spin_unlock_irq(&dinfo->io_lock);
 
-       /* Flush gnttab callback work. Must be done with no locks held. */
-       flush_work(&rinfo->work);
+               /* Flush gnttab callback work. Must be done with no locks held. 
*/
+               flush_work(&rinfo->work);
 
-       /* Free resources associated with old device channel. */
-       for (i = 0; i < dinfo->nr_ring_pages; i++) {
-               if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
-                       gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
-                       rinfo->ring_ref[i] = GRANT_INVALID_REF;
+               /* Free resources associated with old device channel. */
+               for (i = 0; i < dinfo->pages_per_ring; i++) {
+                       if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
+                               gnttab_end_foreign_access(rinfo->ring_ref[i], 
0, 0);
+                               rinfo->ring_ref[i] = GRANT_INVALID_REF;
+                       }
                }
-       }
-       free_pages((unsigned long)rinfo->ring.sring, 
get_order(dinfo->nr_ring_pages * PAGE_SIZE));
-       rinfo->ring.sring = NULL;
-
-       if (rinfo->irq)
-               unbind_from_irqhandler(rinfo->irq, rinfo);
-       rinfo->evtchn = rinfo->irq = 0;
+               free_pages((unsigned long)rinfo->ring.sring, 
get_order(dinfo->pages_per_ring * PAGE_SIZE));
+               rinfo->ring.sring = NULL;
 
+               if (rinfo->irq)
+                       unbind_from_irqhandler(rinfo->irq, rinfo);
+               rinfo->evtchn = rinfo->irq = 0;
+       }
 }
 
 static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info 
*rinfo,
@@ -1276,6 +1284,26 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
        return IRQ_HANDLED;
 }
 
+static void destroy_blkring(struct xenbus_device *dev,
+                           struct blkfront_ring_info *rinfo)
+{
+       int i;
+
+       if (rinfo->irq)
+               unbind_from_irqhandler(rinfo->irq, rinfo);
+       if (rinfo->evtchn)
+               xenbus_free_evtchn(dev, rinfo->evtchn);
+
+       for (i = 0; i < rinfo->dinfo->pages_per_ring; i++) {
+               if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
+                       gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
+                       rinfo->ring_ref[i] = GRANT_INVALID_REF;
+               }
+       }
+       free_pages((unsigned long)rinfo->ring.sring,
+                  get_order(rinfo->dinfo->pages_per_ring * PAGE_SIZE));
+       rinfo->ring.sring = NULL;
+}
 
 static int setup_blkring(struct xenbus_device *dev,
                         struct blkfront_ring_info *rinfo)
@@ -1283,10 +1311,10 @@ static int setup_blkring(struct xenbus_device *dev,
        struct blkif_sring *sring;
        int err, i;
        struct blkfront_dev_info *dinfo = rinfo->dinfo;
-       unsigned long ring_size = dinfo->nr_ring_pages * PAGE_SIZE;
+       unsigned long ring_size = dinfo->pages_per_ring * PAGE_SIZE;
        grant_ref_t gref[XENBUS_MAX_RING_PAGES];
 
-       for (i = 0; i < dinfo->nr_ring_pages; i++)
+       for (i = 0; i < dinfo->pages_per_ring; i++)
                rinfo->ring_ref[i] = GRANT_INVALID_REF;
 
        sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
@@ -1298,13 +1326,13 @@ static int setup_blkring(struct xenbus_device *dev,
        SHARED_RING_INIT(sring);
        FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
 
-       err = xenbus_grant_ring(dev, rinfo->ring.sring, dinfo->nr_ring_pages, 
gref);
+       err = xenbus_grant_ring(dev, rinfo->ring.sring, dinfo->pages_per_ring, 
gref);
        if (err < 0) {
                free_pages((unsigned long)sring, get_order(ring_size));
                rinfo->ring.sring = NULL;
                goto fail;
        }
-       for (i = 0; i < dinfo->nr_ring_pages; i++)
+       for (i = 0; i < dinfo->pages_per_ring; i++)
                rinfo->ring_ref[i] = gref[i];
 
        err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
@@ -1322,7 +1350,7 @@ static int setup_blkring(struct xenbus_device *dev,
 
        return 0;
 fail:
-       blkif_free(dinfo, 0);
+       destroy_blkring(dev, rinfo);
        return err;
 }
 
@@ -1333,65 +1361,76 @@ static int talk_to_blkback(struct xenbus_device *dev,
 {
        const char *message = NULL;
        struct xenbus_transaction xbt;
-       int err, i;
+       int err, i, r_index;
        unsigned int max_page_order = 0;
        unsigned int ring_page_order = 0;
-       struct blkfront_ring_info *rinfo = &dinfo->rinfo;
+       struct blkfront_ring_info *rinfo;
 
        err = xenbus_scanf(XBT_NIL, dinfo->xbdev->otherend,
                           "max-ring-page-order", "%u", &max_page_order);
        if (err != 1)
-               dinfo->nr_ring_pages = 1;
+               dinfo->pages_per_ring = 1;
        else {
                ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
-               dinfo->nr_ring_pages = 1 << ring_page_order;
+               dinfo->pages_per_ring = 1 << ring_page_order;
        }
 
-       /* Create shared ring, alloc event channel. */
-       err = setup_blkring(dev, rinfo);
-       if (err)
-               goto out;
+       for (r_index = 0; r_index < dinfo->nr_rings; r_index++) {
+               rinfo = &dinfo->rinfo[r_index];
+               /* Create shared ring, alloc event channel. */
+               err = setup_blkring(dev, rinfo);
+               if (err)
+                       goto out;
+       }
 
 again:
        err = xenbus_transaction_start(&xbt);
        if (err) {
                xenbus_dev_fatal(dev, err, "starting transaction");
-               goto destroy_blkring;
+               goto out;
        }
 
-       if (dinfo->nr_ring_pages == 1) {
-               err = xenbus_printf(xbt, dev->nodename,
-                                   "ring-ref", "%u", rinfo->ring_ref[0]);
-               if (err) {
-                       message = "writing ring-ref";
-                       goto abort_transaction;
-               }
-       } else {
-               err = xenbus_printf(xbt, dev->nodename,
-                                   "ring-page-order", "%u", ring_page_order);
-               if (err) {
-                       message = "writing ring-page-order";
-                       goto abort_transaction;
-               }
-
-               for (i = 0; i < dinfo->nr_ring_pages; i++) {
-                       char ring_ref_name[RINGREF_NAME_LEN];
+       if (dinfo->nr_rings == 1) {
+               rinfo = &dinfo->rinfo[0];
 
-                       snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", 
i);
-                       err = xenbus_printf(xbt, dev->nodename, ring_ref_name,
-                                           "%u", rinfo->ring_ref[i]);
+               if (dinfo->pages_per_ring == 1) {
+                       err = xenbus_printf(xbt, dev->nodename,
+                                           "ring-ref", "%u", 
rinfo->ring_ref[0]);
                        if (err) {
                                message = "writing ring-ref";
                                goto abort_transaction;
                        }
+               } else {
+                       err = xenbus_printf(xbt, dev->nodename,
+                                           "ring-page-order", "%u", 
ring_page_order);
+                       if (err) {
+                               message = "writing ring-page-order";
+                               goto abort_transaction;
+                       }
+
+                       for (i = 0; i < dinfo->pages_per_ring; i++) {
+                               char ring_ref_name[RINGREF_NAME_LEN];
+
+                               snprintf(ring_ref_name, RINGREF_NAME_LEN, 
"ring-ref%u", i);
+                               err = xenbus_printf(xbt, dev->nodename, 
ring_ref_name,
+                                                   "%u", rinfo->ring_ref[i]);
+                               if (err) {
+                                       message = "writing ring-ref";
+                                       goto abort_transaction;
+                               }
+                       }
                }
-       }
-       err = xenbus_printf(xbt, dev->nodename,
-                           "event-channel", "%u", rinfo->evtchn);
-       if (err) {
-               message = "writing event-channel";
+               err = xenbus_printf(xbt, dev->nodename,
+                                   "event-channel", "%u", rinfo->evtchn);
+               if (err) {
+                       message = "writing event-channel";
+                       goto abort_transaction;
+               }
+       } else {
+               /* Not supported at this stage */
                goto abort_transaction;
        }
+
        err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
                            XEN_IO_PROTO_ABI_NATIVE);
        if (err) {
@@ -1409,12 +1448,16 @@ again:
                if (err == -EAGAIN)
                        goto again;
                xenbus_dev_fatal(dev, err, "completing transaction");
-               goto destroy_blkring;
+               goto out;
        }
 
-       for (i = 0; i < BLK_RING_SIZE(dinfo); i++)
-               rinfo->shadow[i].req.u.rw.id = i+1;
-       rinfo->shadow[BLK_RING_SIZE(dinfo)-1].req.u.rw.id = 0x0fffffff;
+       for (r_index = 0; r_index < dinfo->nr_rings; r_index++) {
+               rinfo = &dinfo->rinfo[r_index];
+
+               for (i = 0; i < BLK_RING_SIZE(dinfo); i++)
+                       rinfo->shadow[i].req.u.rw.id = i+1;
+               rinfo->shadow[BLK_RING_SIZE(dinfo)-1].req.u.rw.id = 0x0fffffff;
+       }
        xenbus_switch_state(dev, XenbusStateInitialised);
 
        return 0;
@@ -1423,9 +1466,9 @@ again:
        xenbus_transaction_end(xbt, 1);
        if (message)
                xenbus_dev_fatal(dev, err, "%s", message);
- destroy_blkring:
-       blkif_free(dinfo, 0);
  out:
+       while (--r_index >= 0)
+               destroy_blkring(dev, &dinfo->rinfo[r_index]);
        return err;
 }
 
@@ -1438,7 +1481,7 @@ again:
 static int blkfront_probe(struct xenbus_device *dev,
                          const struct xenbus_device_id *id)
 {
-       int err, vdevice;
+       int err, vdevice, r_index;
        struct blkfront_dev_info *dinfo;
        struct blkfront_ring_info *rinfo;
 
@@ -1490,17 +1533,29 @@ static int blkfront_probe(struct xenbus_device *dev,
                return -ENOMEM;
        }
 
-       rinfo = &dinfo->rinfo;
        mutex_init(&dinfo->mutex);
        spin_lock_init(&dinfo->io_lock);
        dinfo->xbdev = dev;
        dinfo->vdevice = vdevice;
-       INIT_LIST_HEAD(&rinfo->grants);
-       INIT_LIST_HEAD(&rinfo->indirect_pages);
-       rinfo->persistent_gnts_c = 0;
        dinfo->connected = BLKIF_STATE_DISCONNECTED;
-       rinfo->dinfo = dinfo;
-       INIT_WORK(&rinfo->work, blkif_restart_queue);
+
+       dinfo->nr_rings = 1;
+       dinfo->rinfo = kzalloc(sizeof(*rinfo) * dinfo->nr_rings, GFP_KERNEL);
+       if (!dinfo->rinfo) {
+               xenbus_dev_fatal(dev, -ENOMEM, "allocating ring_info 
structure");
+               kfree(dinfo);
+               return -ENOMEM;
+       }
+
+       for (r_index = 0; r_index < dinfo->nr_rings; r_index++) {
+               rinfo = &dinfo->rinfo[r_index];
+
+               INIT_LIST_HEAD(&rinfo->grants);
+               INIT_LIST_HEAD(&rinfo->indirect_pages);
+               rinfo->persistent_gnts_c = 0;
+               rinfo->dinfo = dinfo;
+               INIT_WORK(&rinfo->work, blkif_restart_queue);
+       }
 
        /* Front end dir is a number, which is used as the id. */
        dinfo->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
@@ -1526,7 +1581,7 @@ static void split_bio_end(struct bio *bio, int error)
 
 static int blkif_recover(struct blkfront_dev_info *dinfo)
 {
-       int i;
+       int i, r_index;
        struct request *req, *n;
        struct blk_shadow *copy;
        int rc;
@@ -1536,56 +1591,62 @@ static int blkif_recover(struct blkfront_dev_info 
*dinfo)
        int pending, size;
        struct split_bio *split_bio;
        struct list_head requests;
-       struct blkfront_ring_info *rinfo = &dinfo->rinfo;
-
-       /* Stage 1: Make a safe copy of the shadow state. */
-       copy = kmemdup(rinfo->shadow, sizeof(rinfo->shadow),
-                      GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
-       if (!copy)
-               return -ENOMEM;
-
-       /* Stage 2: Set up free list. */
-       memset(&rinfo->shadow, 0, sizeof(rinfo->shadow));
-       for (i = 0; i < BLK_RING_SIZE(dinfo); i++)
-               rinfo->shadow[i].req.u.rw.id = i+1;
-       rinfo->shadow_free = rinfo->ring.req_prod_pvt;
-       rinfo->shadow[BLK_RING_SIZE(dinfo)-1].req.u.rw.id = 0x0fffffff;
-
-       rc = blkfront_gather_backend_features(dinfo);
-       if (rc) {
-               kfree(copy);
-               return rc;
-       }
+       struct blkfront_ring_info *rinfo;
 
+       __blkfront_gather_backend_features(dinfo);
        segs = dinfo->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
        blk_queue_max_segments(dinfo->rq, segs);
        bio_list_init(&bio_list);
        INIT_LIST_HEAD(&requests);
-       for (i = 0; i < BLK_RING_SIZE(dinfo); i++) {
-               /* Not in use? */
-               if (!copy[i].request)
-                       continue;
 
-               /*
-                * Get the bios in the request so we can re-queue them.
-                */
-               if (copy[i].request->cmd_flags &
-                   (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
+       for (r_index = 0; r_index < dinfo->nr_rings; r_index++) {
+               rinfo = &dinfo->rinfo[r_index];
+
+               /* Stage 1: Make a safe copy of the shadow state. */
+               copy = kmemdup(rinfo->shadow, sizeof(rinfo->shadow),
+                              GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
+               if (!copy)
+                       return -ENOMEM;
+
+               /* Stage 2: Set up free list. */
+               memset(&rinfo->shadow, 0, sizeof(rinfo->shadow));
+               for (i = 0; i < BLK_RING_SIZE(dinfo); i++)
+                       rinfo->shadow[i].req.u.rw.id = i+1;
+               rinfo->shadow_free = rinfo->ring.req_prod_pvt;
+               rinfo->shadow[BLK_RING_SIZE(dinfo)-1].req.u.rw.id = 0x0fffffff;
+
+               rc = blkfront_setup_indirect(rinfo);
+               if (rc) {
+                       kfree(copy);
+                       return rc;
+               }
+
+               for (i = 0; i < BLK_RING_SIZE(dinfo); i++) {
+                       /* Not in use? */
+                       if (!copy[i].request)
+                               continue;
+
                        /*
-                        * Flush operations don't contain bios, so
-                        * we need to requeue the whole request
+                        * Get the bios in the request so we can re-queue them.
                         */
-                       list_add(&copy[i].request->queuelist, &requests);
-                       continue;
+                       if (copy[i].request->cmd_flags &
+                           (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
+                               /*
+                                * Flush operations don't contain bios, so
+                                * we need to requeue the whole request
+                                */
+                               list_add(&copy[i].request->queuelist, 
&requests);
+                               continue;
+                       }
+                       merge_bio.head = copy[i].request->bio;
+                       merge_bio.tail = copy[i].request->biotail;
+                       bio_list_merge(&bio_list, &merge_bio);
+                       copy[i].request->bio = NULL;
+                       blk_end_request_all(copy[i].request, 0);
                }
-               merge_bio.head = copy[i].request->bio;
-               merge_bio.tail = copy[i].request->biotail;
-               bio_list_merge(&bio_list, &merge_bio);
-               copy[i].request->bio = NULL;
-               blk_end_request_all(copy[i].request, 0);
-       }
 
-       kfree(copy);
+               kfree(copy);
+       }
 
        xenbus_switch_state(dinfo->xbdev, XenbusStateConnected);
 
@@ -1594,8 +1655,12 @@ static int blkif_recover(struct blkfront_dev_info *dinfo)
        /* Now safe for us to use the shared ring */
        dinfo->connected = BLKIF_STATE_CONNECTED;
 
-       /* Kick any other new requests queued since we resumed */
-       kick_pending_request_queues(rinfo);
+       for (r_index = 0; r_index < dinfo->nr_rings; r_index++) {
+               rinfo = &dinfo->rinfo[r_index];
+
+               /* Kick any other new requests queued since we resumed */
+               kick_pending_request_queues(rinfo);
+       }
 
        list_for_each_entry_safe(req, n, &requests, queuelist) {
                /* Requeue pending requests (flush or discard) */
@@ -1729,6 +1794,38 @@ static void blkfront_setup_discard(struct 
blkfront_dev_info *dinfo)
                dinfo->feature_secdiscard = !!discard_secure;
 }
 
+static void blkfront_clean_ring(struct blkfront_ring_info *rinfo)
+{
+       int i;
+
+       for (i = 0; i < BLK_RING_SIZE(rinfo->dinfo); i++) {
+               kfree(rinfo->shadow[i].grants_used);
+               rinfo->shadow[i].grants_used = NULL;
+               kfree(rinfo->shadow[i].sg);
+               rinfo->shadow[i].sg = NULL;
+               kfree(rinfo->shadow[i].indirect_grants);
+               rinfo->shadow[i].indirect_grants = NULL;
+       }
+       if (!list_empty(&rinfo->indirect_pages)) {
+               struct page *indirect_page, *n;
+               list_for_each_entry_safe(indirect_page, n, 
&rinfo->indirect_pages, lru) {
+                       list_del(&indirect_page->lru);
+                       __free_page(indirect_page);
+               }
+       }
+
+       if (!list_empty(&rinfo->grants)) {
+               struct grant *gnt_list_entry, *n;
+               list_for_each_entry_safe(gnt_list_entry, n,
+                               &rinfo->grants, node) {
+                       list_del(&gnt_list_entry->node);
+                       if (rinfo->dinfo->feature_persistent)
+                               __free_page(pfn_to_page(gnt_list_entry->pfn));
+                       kfree(gnt_list_entry);
+               }
+       }
+}
+
 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
 {
        unsigned int segs;
@@ -1783,28 +1880,14 @@ static int blkfront_setup_indirect(struct 
blkfront_ring_info *rinfo)
        return 0;
 
 out_of_memory:
-       for (i = 0; i < BLK_RING_SIZE(dinfo); i++) {
-               kfree(rinfo->shadow[i].grants_used);
-               rinfo->shadow[i].grants_used = NULL;
-               kfree(rinfo->shadow[i].sg);
-               rinfo->shadow[i].sg = NULL;
-               kfree(rinfo->shadow[i].indirect_grants);
-               rinfo->shadow[i].indirect_grants = NULL;
-       }
-       if (!list_empty(&rinfo->indirect_pages)) {
-               struct page *indirect_page, *n;
-               list_for_each_entry_safe(indirect_page, n, 
&rinfo->indirect_pages, lru) {
-                       list_del(&indirect_page->lru);
-                       __free_page(indirect_page);
-               }
-       }
+       blkfront_clean_ring(rinfo);
        return -ENOMEM;
 }
 
 /*
  * Gather all backend feature-*
  */
-static int blkfront_gather_backend_features(struct blkfront_dev_info *dinfo)
+static void __blkfront_gather_backend_features(struct blkfront_dev_info *dinfo)
 {
        int err;
        int barrier, flush, discard, persistent;
@@ -1859,8 +1942,25 @@ static int blkfront_gather_backend_features(struct 
blkfront_dev_info *dinfo)
        else
                dinfo->max_indirect_segments = min(indirect_segments,
                                                  xen_blkif_max_segments);
+}
+
+static int blkfront_gather_backend_features(struct blkfront_dev_info *dinfo)
+{
+       int err, i;
+
+       __blkfront_gather_backend_features(dinfo);
 
-       return blkfront_setup_indirect(&dinfo->rinfo);
+       for (i = 0; i < dinfo->nr_rings; i++) {
+               err = blkfront_setup_indirect(&dinfo->rinfo[i]);
+               if (err)
+                       goto out;
+       }
+       return 0;
+
+out:
+       while (--i >= 0)
+               blkfront_clean_ring(&dinfo->rinfo[i]);
+       return err;
 }
 
 /*
@@ -1873,8 +1973,8 @@ static void blkfront_connect(struct blkfront_dev_info 
*dinfo)
        unsigned long sector_size;
        unsigned int physical_sector_size;
        unsigned int binfo;
-       int err;
-       struct blkfront_ring_info *rinfo = &dinfo->rinfo;
+       int err, i;
+       struct blkfront_ring_info *rinfo;
 
        switch (dinfo->connected) {
        case BLKIF_STATE_CONNECTED:
@@ -1951,7 +2051,10 @@ static void blkfront_connect(struct blkfront_dev_info 
*dinfo)
        /* Kick pending requests. */
        spin_lock_irq(&dinfo->io_lock);
        dinfo->connected = BLKIF_STATE_CONNECTED;
-       kick_pending_request_queues(rinfo);
+       for (i = 0; i < dinfo->nr_rings; i++) {
+               rinfo = &dinfo->rinfo[i];
+               kick_pending_request_queues(rinfo);
+       }
        spin_unlock_irq(&dinfo->io_lock);
 
        add_disk(dinfo->gd);
-- 
1.7.10.4


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