xen/blkback: pseudo support for multi hardware queues/rings
Preparatory patch for multiple hardware queues (rings). The number of
rings is unconditionally set to 1, larger number will be enabled in
"xen/blkback: get the number of hardware queues/rings from blkfront".
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v2: Align variables in the structures.
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index dbdf416..310eff3 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -340,7 +340,8 @@
struct work_struct free_work;
unsigned int nr_ring_pages;
/* All rings for this device. */
- struct xen_blkif_ring ring;
+ struct xen_blkif_ring *rings;
+ unsigned int nr_rings;
};
struct seg_buf {
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index e4bfc92..f5bfedd 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -86,9 +86,11 @@
{
int err;
char name[BLKBACK_NAME_LEN];
+ struct xen_blkif_ring *ring;
+ int i;
/* Not ready to connect? */
- if (!blkif->ring.irq || !blkif->vbd.bdev)
+ if (!blkif->rings || !blkif->rings[0].irq || !blkif->vbd.bdev)
return;
/* Already connected? */
@@ -113,19 +115,55 @@
}
invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
- blkif->ring.xenblkd = kthread_run(xen_blkif_schedule, &blkif->ring, "%s", name);
- if (IS_ERR(blkif->ring.xenblkd)) {
- err = PTR_ERR(blkif->ring.xenblkd);
- blkif->ring.xenblkd = NULL;
- xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
- return;
+ for (i = 0; i < blkif->nr_rings; i++) {
+ ring = &blkif->rings[i];
+ ring->xenblkd = kthread_run(xen_blkif_schedule, ring, "%s-%d", name, i);
+ if (IS_ERR(ring->xenblkd)) {
+ err = PTR_ERR(ring->xenblkd);
+ ring->xenblkd = NULL;
+ xenbus_dev_fatal(blkif->be->dev, err,
+ "start %s-%d xenblkd", name, i);
+ goto out;
+ }
}
+ return;
+
+out:
+ while (--i >= 0) {
+ ring = &blkif->rings[i];
+ kthread_stop(ring->xenblkd);
+ }
+ return;
+}
+
+static int xen_blkif_alloc_rings(struct xen_blkif *blkif)
+{
+ unsigned int r;
+
+ blkif->rings = kzalloc(blkif->nr_rings * sizeof(struct xen_blkif_ring), GFP_KERNEL);
+ if (!blkif->rings)
+ return -ENOMEM;
+
+ for (r = 0; r < blkif->nr_rings; r++) {
+ struct xen_blkif_ring *ring = &blkif->rings[r];
+
+ spin_lock_init(&ring->blk_ring_lock);
+ init_waitqueue_head(&ring->wq);
+ INIT_LIST_HEAD(&ring->pending_free);
+
+ spin_lock_init(&ring->pending_free_lock);
+ init_waitqueue_head(&ring->pending_free_wq);
+ init_waitqueue_head(&ring->shutdown_wq);
+ ring->blkif = blkif;
+ xen_blkif_get(blkif);
+ }
+
+ return 0;
}
static struct xen_blkif *xen_blkif_alloc(domid_t domid)
{
struct xen_blkif *blkif;
- struct xen_blkif_ring *ring;
BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
@@ -143,15 +181,11 @@
blkif->st_print = jiffies;
INIT_WORK(&blkif->persistent_purge_work, xen_blkbk_unmap_purged_grants);
- ring = &blkif->ring;
- ring->blkif = blkif;
- spin_lock_init(&ring->blk_ring_lock);
- init_waitqueue_head(&ring->wq);
-
- INIT_LIST_HEAD(&ring->pending_free);
- spin_lock_init(&ring->pending_free_lock);
- init_waitqueue_head(&ring->pending_free_wq);
- init_waitqueue_head(&ring->shutdown_wq);
+ blkif->nr_rings = 1;
+ if (xen_blkif_alloc_rings(blkif)) {
+ kmem_cache_free(xen_blkif_cachep, blkif);
+ return ERR_PTR(-ENOMEM);
+ }
return blkif;
}
@@ -216,50 +250,54 @@
static int xen_blkif_disconnect(struct xen_blkif *blkif)
{
struct pending_req *req, *n;
- int i = 0, j;
- struct xen_blkif_ring *ring = &blkif->ring;
+ unsigned int j, r;
- if (ring->xenblkd) {
- kthread_stop(ring->xenblkd);
- wake_up(&ring->shutdown_wq);
- ring->xenblkd = NULL;
+ for (r = 0; r < blkif->nr_rings; r++) {
+ struct xen_blkif_ring *ring = &blkif->rings[r];
+ unsigned int i = 0;
+
+ if (ring->xenblkd) {
+ kthread_stop(ring->xenblkd);
+ wake_up(&ring->shutdown_wq);
+ ring->xenblkd = NULL;
+ }
+
+ /* The above kthread_stop() guarantees that at this point we
+ * don't have any discard_io or other_io requests. So, checking
+ * for inflight IO is enough.
+ */
+ if (atomic_read(&ring->inflight) > 0)
+ return -EBUSY;
+
+ if (ring->irq) {
+ unbind_from_irqhandler(ring->irq, ring);
+ ring->irq = 0;
+ }
+
+ if (ring->blk_rings.common.sring) {
+ xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
+ ring->blk_rings.common.sring = NULL;
+ }
+
+ /* Remove all persistent grants and the cache of ballooned pages. */
+ xen_blkbk_free_caches(ring);
+
+ /* Check that there is no request in use */
+ list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
+ list_del(&req->free_list);
+
+ for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
+ kfree(req->segments[j]);
+
+ for (j = 0; j < MAX_INDIRECT_PAGES; j++)
+ kfree(req->indirect_pages[j]);
+
+ kfree(req);
+ i++;
+ }
+
+ WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
}
-
- /* The above kthread_stop() guarantees that at this point we
- * don't have any discard_io or other_io requests. So, checking
- * for inflight IO is enough.
- */
- if (atomic_read(&ring->inflight) > 0)
- return -EBUSY;
-
- if (ring->irq) {
- unbind_from_irqhandler(ring->irq, ring);
- ring->irq = 0;
- }
-
- if (ring->blk_rings.common.sring) {
- xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
- ring->blk_rings.common.sring = NULL;
- }
-
- /* Remove all persistent grants and the cache of ballooned pages. */
- xen_blkbk_free_caches(ring);
-
- /* Check that there is no request in use */
- list_for_each_entry_safe(req, n, &ring->pending_free, free_list) {
- list_del(&req->free_list);
-
- for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
- kfree(req->segments[j]);
-
- for (j = 0; j < MAX_INDIRECT_PAGES; j++)
- kfree(req->indirect_pages[j]);
-
- kfree(req);
- i++;
- }
-
- WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
blkif->nr_ring_pages = 0;
return 0;
@@ -279,6 +317,7 @@
BUG_ON(!list_empty(&blkif->free_pages));
BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
+ kfree(blkif->rings);
kmem_cache_free(xen_blkif_cachep, blkif);
}
@@ -427,6 +466,7 @@
static int xen_blkbk_remove(struct xenbus_device *dev)
{
struct backend_info *be = dev_get_drvdata(&dev->dev);
+ unsigned int i;
pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
@@ -443,7 +483,8 @@
if (be->blkif) {
xen_blkif_disconnect(be->blkif);
- xen_blkif_put(be->blkif);
+ for (i = 0; i < be->blkif->nr_rings; i++)
+ xen_blkif_put(be->blkif);
}
kfree(be->mode);
@@ -826,51 +867,43 @@
xenbus_transaction_end(xbt, 1);
}
-
-static int connect_ring(struct backend_info *be)
+/*
+ * Each ring may have multi pages, depends on "ring-page-order".
+ */
+static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
{
- struct xenbus_device *dev = be->dev;
unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
- unsigned int evtchn, nr_grefs, ring_page_order;
- unsigned int pers_grants;
- char protocol[64] = "";
struct pending_req *req, *n;
int err, i, j;
- struct xen_blkif_ring *ring = &be->blkif->ring;
+ struct xen_blkif *blkif = ring->blkif;
+ struct xenbus_device *dev = blkif->be->dev;
+ unsigned int ring_page_order, nr_grefs, evtchn;
- pr_debug("%s %s\n", __func__, dev->otherend);
-
- err = xenbus_scanf(XBT_NIL, dev->otherend, "event-channel", "%u",
+ err = xenbus_scanf(XBT_NIL, dir, "event-channel", "%u",
&evtchn);
if (err != 1) {
err = -EINVAL;
- xenbus_dev_fatal(dev, err, "reading %s/event-channel",
- dev->otherend);
+ xenbus_dev_fatal(dev, err, "reading %s/event-channel", dir);
return err;
}
- pr_info("event-channel %u\n", evtchn);
err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u",
&ring_page_order);
if (err != 1) {
- err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref",
- "%u", &ring_ref[0]);
+ err = xenbus_scanf(XBT_NIL, dir, "ring-ref", "%u", &ring_ref[0]);
if (err != 1) {
err = -EINVAL;
- xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
- dev->otherend);
+ xenbus_dev_fatal(dev, err, "reading %s/ring-ref", dir);
return err;
}
nr_grefs = 1;
- pr_info("%s:using single page: ring-ref %d\n", dev->otherend,
- ring_ref[0]);
} else {
unsigned int i;
if (ring_page_order > xen_blkif_max_ring_order) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d",
- dev->otherend, ring_page_order,
+ dir, ring_page_order,
xen_blkif_max_ring_order);
return err;
}
@@ -880,46 +913,17 @@
char ring_ref_name[RINGREF_NAME_LEN];
snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
- err = xenbus_scanf(XBT_NIL, dev->otherend, ring_ref_name,
+ err = xenbus_scanf(XBT_NIL, dir, ring_ref_name,
"%u", &ring_ref[i]);
if (err != 1) {
err = -EINVAL;
xenbus_dev_fatal(dev, err, "reading %s/%s",
- dev->otherend, ring_ref_name);
+ dir, ring_ref_name);
return err;
}
- pr_info("ring-ref%u: %u\n", i, ring_ref[i]);
}
}
-
- be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
- err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
- "%63s", protocol, NULL);
- if (err)
- strcpy(protocol, "unspecified, assuming default");
- else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
- be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
- else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
- be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
- else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
- be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
- else {
- xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
- return -1;
- }
- err = xenbus_gather(XBT_NIL, dev->otherend,
- "feature-persistent", "%u",
- &pers_grants, NULL);
- if (err)
- pers_grants = 0;
-
- be->blkif->vbd.feature_gnt_persistent = pers_grants;
- be->blkif->vbd.overflow_max_grants = 0;
- be->blkif->nr_ring_pages = nr_grefs;
-
- pr_info("ring-pages:%d, event-channel %d, protocol %d (%s) %s\n",
- nr_grefs, evtchn, be->blkif->blk_protocol, protocol,
- pers_grants ? "persistent grants" : "");
+ blkif->nr_ring_pages = nr_grefs;
for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
req = kzalloc(sizeof(*req), GFP_KERNEL);
@@ -964,6 +968,71 @@
kfree(req);
}
return -ENOMEM;
+
+}
+
+static int connect_ring(struct backend_info *be)
+{
+ struct xenbus_device *dev = be->dev;
+ unsigned int pers_grants;
+ char protocol[64] = "";
+ int err, i;
+ char *xspath;
+ size_t xspathsize;
+ const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
+
+ pr_debug("%s %s\n", __func__, dev->otherend);
+
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
+ err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
+ "%63s", protocol, NULL);
+ if (err)
+ strcpy(protocol, "unspecified, assuming default");
+ else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
+ else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
+ else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
+ be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
+ else {
+ xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
+ return -1;
+ }
+ err = xenbus_gather(XBT_NIL, dev->otherend,
+ "feature-persistent", "%u",
+ &pers_grants, NULL);
+ if (err)
+ pers_grants = 0;
+
+ be->blkif->vbd.feature_gnt_persistent = pers_grants;
+ be->blkif->vbd.overflow_max_grants = 0;
+
+ pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename,
+ be->blkif->nr_rings, be->blkif->blk_protocol, protocol,
+ pers_grants ? "persistent grants" : "");
+
+ if (be->blkif->nr_rings == 1)
+ return read_per_ring_refs(&be->blkif->rings[0], dev->otherend);
+ else {
+ xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
+ xspath = kmalloc(xspathsize, GFP_KERNEL);
+ if (!xspath) {
+ xenbus_dev_fatal(dev, -ENOMEM, "reading ring references");
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < be->blkif->nr_rings; i++) {
+ memset(xspath, 0, xspathsize);
+ snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend, i);
+ err = read_per_ring_refs(&be->blkif->rings[i], xspath);
+ if (err) {
+ kfree(xspath);
+ return err;
+ }
+ }
+ kfree(xspath);
+ }
+ return 0;
}
static const struct xenbus_device_id xen_blkbk_ids[] = {