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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2/2] Add multi-page ring support to xen-blkfront
Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
drivers/block/xen-blkfront.c | 137 ++++++++++++++++++++++++++++++++----------
1 files changed, 105 insertions(+), 32 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 837b992..1aaa5a4 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -67,7 +67,25 @@ struct blk_shadow {
static struct block_device_operations xlvbd_block_fops;
-#define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE)
+#define BLK_RING_SIZE(_order) \
+ __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE<<(_order))
+
+#define BLKIF_MAX_RING_PAGE_ORDER 2
+#define MAX_BLK_RING_SIZE BLK_RING_SIZE(BLKIF_MAX_RING_PAGE_ORDER)
+
+#define BLKIF_MAX_RING_PAGES (1<<BLKIF_MAX_RING_PAGE_ORDER)
+
+/*
+ * Allow multi page shared ring to be used if the capability is advertised by
+ * the back end.
+ */
+static int allow_multi_page_ring = 1;
+module_param_named(allow_multi_page_ring,
+ allow_multi_page_ring,
+ int,
+ 0);
+MODULE_PARM_DESC(allow_multi_page_ring,
+ "Allow multi page shared ring to be used");
/*
* We have one of these per vbd, whether ide, scsi or 'other'. They
@@ -81,14 +99,15 @@ struct blkfront_info
int vdevice;
blkif_vdev_t handle;
enum blkif_state connected;
- int ring_ref;
+ int ring_ref[BLKIF_MAX_RING_PAGES];
+ int ring_order;
struct blkif_front_ring ring;
struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
unsigned int evtchn, irq;
struct request_queue *rq;
struct work_struct work;
struct gnttab_free_callback callback;
- struct blk_shadow shadow[BLK_RING_SIZE];
+ struct blk_shadow shadow[MAX_BLK_RING_SIZE];
unsigned long shadow_free;
int feature_barrier;
int is_ready;
@@ -102,8 +121,6 @@ struct blkfront_info
static DEFINE_SPINLOCK(blkif_io_lock);
-#define MAXIMUM_OUTSTANDING_BLOCK_REQS \
- (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
#define GRANT_INVALID_REF 0
#define PARTS_PER_DISK 16
@@ -122,7 +139,7 @@ static DEFINE_SPINLOCK(blkif_io_lock);
static int get_id_from_freelist(struct blkfront_info *info)
{
unsigned long free = info->shadow_free;
- BUG_ON(free >= BLK_RING_SIZE);
+ BUG_ON(free >= MAX_BLK_RING_SIZE);
info->shadow_free = info->shadow[free].req.id;
info->shadow[free].req.id = 0x0fffffee; /* debug */
return free;
@@ -495,6 +512,9 @@ static void blkif_restart_queue(struct work_struct *work)
static void blkif_free(struct blkfront_info *info, int suspend)
{
+ int i;
+ unsigned long sring = (unsigned long)info->ring.sring;
+
/* Prevent new requests being issued until we fix things up. */
spin_lock_irq(&blkif_io_lock);
info->connected = suspend ?
@@ -510,12 +530,14 @@ static void blkif_free(struct blkfront_info *info, int
suspend)
flush_scheduled_work();
/* Free resources associated with old device channel. */
- if (info->ring_ref != GRANT_INVALID_REF) {
- gnttab_end_foreign_access(info->ring_ref, 0,
- (unsigned long)info->ring.sring);
- info->ring_ref = GRANT_INVALID_REF;
- info->ring.sring = NULL;
+ for (i = 0; i < (1<<info->ring_order); i++) {
+ if (info->ring_ref[i] != GRANT_INVALID_REF) {
+ gnttab_end_foreign_access(info->ring_ref[i], 0,
+ sring + (i<<PAGE_SHIFT));
+ info->ring_ref[i] = GRANT_INVALID_REF;
+ }
}
+ info->ring.sring = NULL;
if (info->irq)
unbind_from_irqhandler(info->irq, info);
info->evtchn = info->irq = 0;
@@ -605,28 +627,35 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
static int setup_blkring(struct xenbus_device *dev,
struct blkfront_info *info)
{
- struct blkif_sring *sring;
+ int i;
+ unsigned long sring;
int err;
- info->ring_ref = GRANT_INVALID_REF;
+ for (i = 0; i < (1<<info->ring_order); i++)
+ info->ring_ref[i] = GRANT_INVALID_REF;
- sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
+ sring = __get_free_pages(GFP_NOIO | __GFP_HIGH, info->ring_order);
if (!sring) {
xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
return -ENOMEM;
}
- SHARED_RING_INIT(sring);
- FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
+ SHARED_RING_INIT((struct blkif_sring *)sring);
+ FRONT_RING_INIT(&info->ring, (struct blkif_sring *)sring,
+ PAGE_SIZE<<info->ring_order);
sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
- err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
- if (err < 0) {
- free_page((unsigned long)sring);
- info->ring.sring = NULL;
- goto fail;
+ for (i = 0; i < (1<<info->ring_order); i++) {
+ unsigned long addr = sring + (i<<PAGE_SHIFT);
+
+ err = xenbus_grant_ring(dev, virt_to_mfn(addr));
+ if (err < 0) {
+ free_pages(sring, info->ring_order);
+ info->ring.sring = NULL;
+ goto fail;
+ }
+ info->ring_ref[i] = err;
}
- info->ring_ref = err;
err = xenbus_alloc_evtchn(dev, &info->evtchn);
if (err)
@@ -648,6 +677,9 @@ fail:
return err;
}
+#ifndef MIN
+#define MIN(a, b) (((a) < (b)) ? (a) : (b))
+#endif
/* Common code used when first setting up, and when resuming. */
static int talk_to_blkback(struct xenbus_device *dev,
@@ -655,8 +687,24 @@ static int talk_to_blkback(struct xenbus_device *dev,
{
const char *message = NULL;
struct xenbus_transaction xbt;
+ int ring_order;
+ int single_page;
int err;
+ err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+ "max-ring-page-order", "%u", &ring_order,
+ NULL);
+ if (err || !allow_multi_page_ring) {
+ single_page = 1;
+ info->ring_order = 0;
+ dev_dbg(&dev->dev, "using single-page handshake\n");
+ } else {
+ single_page = 0;
+ info->ring_order = MIN(ring_order, BLKIF_MAX_RING_PAGE_ORDER);
+ dev_dbg(&dev->dev, "using multi-page handshake (%d pages)\n",
+ (1<<info->ring_order));
+ }
+
/* Create shared ring, alloc event channel. */
err = setup_blkring(dev, info);
if (err)
@@ -669,18 +717,43 @@ again:
goto destroy_blkring;
}
- err = xenbus_printf(xbt, dev->nodename,
- "ring-ref", "%u", info->ring_ref);
- if (err) {
- message = "writing ring-ref";
- goto abort_transaction;
+ if (single_page) {
+ err = xenbus_printf(xbt, dev->nodename,
+ "ring-ref", "%u", info->ring_ref[0]);
+ if (err) {
+ message = "writing ring-ref";
+ goto abort_transaction;
+ }
+ } else {
+ int i;
+
+ err = xenbus_printf(xbt, dev->nodename,
+ "ring-page-order", "%u", info->ring_order);
+ if (err) {
+ message = "writing ring-page-order";
+ goto abort_transaction;
+ }
+
+ for (i = 0; i < (1<<info->ring_order); i++) {
+ char node[10];
+
+ snprintf(node, sizeof(node), "ring-ref%u", i);
+ err = xenbus_printf(xbt, dev->nodename, node, "%u",
+ info->ring_ref[i]);
+ if (err) {
+ message = "writing ring-ref";
+ goto abort_transaction;
+ }
+ }
}
+
err = xenbus_printf(xbt, dev->nodename,
"event-channel", "%u", info->evtchn);
if (err) {
message = "writing event-channel";
goto abort_transaction;
}
+
err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
XEN_IO_PROTO_ABI_NATIVE);
if (err) {
@@ -747,9 +820,9 @@ static int blkfront_probe(struct xenbus_device *dev,
info->connected = BLKIF_STATE_DISCONNECTED;
INIT_WORK(&info->work, blkif_restart_queue);
- for (i = 0; i < BLK_RING_SIZE; i++)
+ for (i = 0; i < MAX_BLK_RING_SIZE; i++)
info->shadow[i].req.id = i+1;
- info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
+ info->shadow[MAX_BLK_RING_SIZE-1].req.id = 0x0fffffff;
/* Front end dir is a number, which is used as the id. */
info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
@@ -782,13 +855,13 @@ 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++)
+ for (i = 0; i < MAX_BLK_RING_SIZE; i++)
info->shadow[i].req.id = i+1;
info->shadow_free = info->ring.req_prod_pvt;
- info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
+ info->shadow[MAX_BLK_RING_SIZE-1].req.id = 0x0fffffff;
/* Stage 3: Find pending requests and requeue them. */
- for (i = 0; i < BLK_RING_SIZE; i++) {
+ for (i = 0; i < MAX_BLK_RING_SIZE; i++) {
/* Not in use? */
if (copy[i].request == 0)
continue;
--
1.5.6.5
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