RE: [PATCH 3/3] xen/block: add multi-page ring support
From: Paul Durrant
Date: Tue Jun 09 2015 - 04:53:09 EST
> -----Original Message-----
> From: Bob Liu [mailto:bob.liu@xxxxxxxxxx]
> Sent: 09 June 2015 09:50
> To: Bob Liu
> Cc: xen-devel@xxxxxxxxxxxxx; David Vrabel; justing@xxxxxxxxxxxxxxxx;
> konrad.wilk@xxxxxxxxxx; Roger Pau Monne; Paul Durrant; Julien Grall; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH 3/3] xen/block: add multi-page ring support
>
>
> On 06/03/2015 01:40 PM, Bob Liu wrote:
> > Extend xen/block to support multi-page ring, so that more requests can be
> > issued by using more than one pages as the request ring between blkfront
> > and backend.
> > As a result, the performance can get improved significantly.
> >
> > We got some impressive improvements on our highend iscsi storage cluster
> > backend. If using 64 pages as the ring, the IOPS increased about 15 times
> > for the throughput testing and above doubled for the latency testing.
> >
> > The reason was the limit on outstanding requests is 32 if use only one-page
> > ring, but in our case the iscsi lun was spread across about 100 physical
> > drives, 32 was really not enough to keep them busy.
> >
> > Changes in v2:
> > - Rebased to 4.0-rc6.
> > - Document on how multi-page ring feature working to linux io/blkif.h.
> >
> > Changes in v3:
> > - Remove changes to linux io/blkif.h and follow the protocol defined
> > in io/blkif.h of XEN tree.
> > - Rebased to 4.1-rc3
> >
> > Changes in v4:
> > - Turn to use 'ring-page-order' and 'max-ring-page-order'.
> > - A few comments from Roger.
> >
> > Changes in v5:
> > - Clarify with 4k granularity to comment
> > - Address more comments from Roger
> >
> > Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
>
> Also tested the windows PV driver which also works fine when multi-page
> ring feature
> was enabled in Linux backend.
> http://www.xenproject.org/downloads/windows-pv-drivers.html
>
Great! Thanks for verifying that :-)
Paul
> Regards,
> -Bob
>
> > ---
> > drivers/block/xen-blkback/blkback.c | 13 ++++
> > drivers/block/xen-blkback/common.h | 2 +
> > drivers/block/xen-blkback/xenbus.c | 89 +++++++++++++++++------
> > drivers/block/xen-blkfront.c | 135 +++++++++++++++++++++++++----
> ------
> > 4 files changed, 180 insertions(+), 59 deletions(-)
> >
> > diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-
> blkback/blkback.c
> > index 713fc9f..2126842 100644
> > --- a/drivers/block/xen-blkback/blkback.c
> > +++ b/drivers/block/xen-blkback/blkback.c
> > @@ -84,6 +84,13 @@ MODULE_PARM_DESC(max_persistent_grants,
> > "Maximum number of grants to map persistently");
> >
> > /*
> > + * Maximum order of pages to be used for the shared ring between front
> and
> > + * backend, 4KB page granularity is used.
> > + */
> > +unsigned int xen_blkif_max_ring_order =
> XENBUS_MAX_RING_PAGE_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");
> > +/*
> > * The LRU mechanism to clean the lists of persistent grants needs to
> > * be executed periodically. The time interval between consecutive
> executions
> > * of the purge mechanism is set in ms.
> > @@ -1438,6 +1445,12 @@ static int __init xen_blkif_init(void)
> > if (!xen_domain())
> > return -ENODEV;
> >
> > + if (xen_blkif_max_ring_order > XENBUS_MAX_RING_PAGE_ORDER)
> {
> > + pr_info("Invalid max_ring_order (%d), will use default max:
> %d.\n",
> > + xen_blkif_max_ring_order,
> XENBUS_MAX_RING_PAGE_ORDER);
> > + xen_blkif_max_ring_order =
> XENBUS_MAX_RING_PAGE_ORDER;
> > + }
> > +
> > rc = xen_blkif_interface_init();
> > if (rc)
> > goto failed_init;
> > diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-
> blkback/common.h
> > index 043f13b..8ccc49d 100644
> > --- a/drivers/block/xen-blkback/common.h
> > +++ b/drivers/block/xen-blkback/common.h
> > @@ -44,6 +44,7 @@
> > #include <xen/interface/io/blkif.h>
> > #include <xen/interface/io/protocols.h>
> >
> > +extern unsigned int xen_blkif_max_ring_order;
> > /*
> > * This is the maximum number of segments that would be allowed in
> indirect
> > * requests. This value will also be passed to the frontend.
> > @@ -320,6 +321,7 @@ struct xen_blkif {
> > struct work_struct free_work;
> > /* Thread shutdown wait queue. */
> > wait_queue_head_t shutdown_wq;
> > + unsigned int nr_ring_pages;
> > };
> >
> > struct seg_buf {
> > diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-
> blkback/xenbus.c
> > index c212d41..deb3f00 100644
> > --- a/drivers/block/xen-blkback/xenbus.c
> > +++ b/drivers/block/xen-blkback/xenbus.c
> > @@ -25,6 +25,7 @@
> >
> > /* Enlarge the array size in order to fully show blkback name. */
> > #define BLKBACK_NAME_LEN (20)
> > +#define RINGREF_NAME_LEN (20)
> >
> > struct backend_info {
> > struct xenbus_device *dev;
> > @@ -156,8 +157,8 @@ static struct xen_blkif *xen_blkif_alloc(domid_t
> domid)
> > return blkif;
> > }
> >
> > -static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t gref,
> > - unsigned int evtchn)
> > +static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref,
> > + unsigned int nr_grefs, unsigned int evtchn)
> > {
> > int err;
> >
> > @@ -165,7 +166,7 @@ static int xen_blkif_map(struct xen_blkif *blkif,
> grant_ref_t gref,
> > if (blkif->irq)
> > return 0;
> >
> > - err = xenbus_map_ring_valloc(blkif->be->dev, &gref, 1,
> > + err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs,
> > &blkif->blk_ring);
> > if (err < 0)
> > return err;
> > @@ -175,21 +176,21 @@ static int xen_blkif_map(struct xen_blkif *blkif,
> grant_ref_t gref,
> > {
> > struct blkif_sring *sring;
> > sring = (struct blkif_sring *)blkif->blk_ring;
> > - BACK_RING_INIT(&blkif->blk_rings.native, sring,
> PAGE_SIZE);
> > + BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE
> * nr_grefs);
> > break;
> > }
> > case BLKIF_PROTOCOL_X86_32:
> > {
> > struct blkif_x86_32_sring *sring_x86_32;
> > sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring;
> > - BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32,
> PAGE_SIZE);
> > + BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32,
> PAGE_SIZE * nr_grefs);
> > break;
> > }
> > case BLKIF_PROTOCOL_X86_64:
> > {
> > struct blkif_x86_64_sring *sring_x86_64;
> > sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring;
> > - BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64,
> PAGE_SIZE);
> > + BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64,
> PAGE_SIZE * nr_grefs);
> > break;
> > }
> > default:
> > @@ -270,7 +271,7 @@ static void xen_blkif_free(struct xen_blkif *blkif)
> > i++;
> > }
> >
> > - WARN_ON(i != XEN_BLKIF_REQS_PER_PAGE);
> > + WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif-
> >nr_ring_pages));
> >
> > kmem_cache_free(xen_blkif_cachep, blkif);
> > }
> > @@ -555,6 +556,11 @@ static int xen_blkbk_probe(struct xenbus_device
> *dev,
> > if (err)
> > goto fail;
> >
> > + err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-
> order", "%u",
> > + xen_blkif_max_ring_order);
> > + if (err)
> > + pr_warn("%s write out 'max-ring-page-order' failed\n",
> __func__);
> > +
> > err = xenbus_switch_state(dev, XenbusStateInitWait);
> > if (err)
> > goto fail;
> > @@ -818,8 +824,8 @@ again:
> > static int connect_ring(struct backend_info *be)
> > {
> > struct xenbus_device *dev = be->dev;
> > - unsigned long ring_ref;
> > - unsigned int evtchn;
> > + unsigned int ring_ref[XENBUS_MAX_RING_PAGES];
> > + unsigned int evtchn, nr_grefs, ring_page_order;
> > unsigned int pers_grants;
> > char protocol[64] = "";
> > struct pending_req *req, *n;
> > @@ -827,14 +833,57 @@ static int connect_ring(struct backend_info *be)
> >
> > pr_debug("%s %s\n", __func__, dev->otherend);
> >
> > - err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu",
> > - &ring_ref, "event-channel", "%u", &evtchn, NULL);
> > - if (err) {
> > - xenbus_dev_fatal(dev, err,
> > - "reading %s/ring-ref and event-channel",
> > + err = xenbus_scanf(XBT_NIL, dev->otherend, "event-channel",
> "%u",
> > + &evtchn);
> > + if (err != 1) {
> > + err = -EINVAL;
> > + xenbus_dev_fatal(dev, err, "reading %s/event-channel",
> > dev->otherend);
> > 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]);
> > + if (err != 1) {
> > + err = -EINVAL;
> > + xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
> > + dev->otherend);
> > + 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,
> > + xen_blkif_max_ring_order);
> > + return err;
> > + }
> > +
> > + nr_grefs = 1 << ring_page_order;
> > + for (i = 0; i < nr_grefs; i++) {
> > + 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,
> > + "%u", &ring_ref[i]);
> > + if (err != 1) {
> > + err = -EINVAL;
> > + xenbus_dev_fatal(dev, err, "reading %s/%s",
> > + dev->otherend,
> 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",
> > @@ -859,12 +908,13 @@ static int connect_ring(struct backend_info *be)
> >
> > 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-ref %ld, event-channel %d, protocol %d (%s) %s\n",
> > - ring_ref, evtchn, be->blkif->blk_protocol, protocol,
> > + 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" : "");
> >
> > - for (i = 0; i < XEN_BLKIF_REQS_PER_PAGE; i++) {
> > + for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
> > req = kzalloc(sizeof(*req), GFP_KERNEL);
> > if (!req)
> > goto fail;
> > @@ -883,10 +933,9 @@ static int connect_ring(struct backend_info *be)
> > }
> >
> > /* Map the shared frame, irq etc. */
> > - err = xen_blkif_map(be->blkif, ring_ref, evtchn);
> > + err = xen_blkif_map(be->blkif, ring_ref, nr_grefs, evtchn);
> > if (err) {
> > - xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u",
> > - ring_ref, evtchn);
> > + xenbus_dev_fatal(dev, err, "mapping ring-ref port %u",
> evtchn);
> > return err;
> > }
> >
> > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> > index 88e23fd..d3c1a95 100644
> > --- a/drivers/block/xen-blkfront.c
> > +++ b/drivers/block/xen-blkfront.c
> > @@ -98,7 +98,21 @@ static unsigned int xen_blkif_max_segments = 32;
> > module_param_named(max, xen_blkif_max_segments, int, S_IRUGO);
> > MODULE_PARM_DESC(max, "Maximum amount of segments in indirect
> requests (default is 32)");
> >
> > -#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
> > +/*
> > + * Maximum order of pages to be used for the shared ring between front
> and
> > + * backend, 4KB page granularity is used.
> > + */
> > +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(info) __CONST_RING_SIZE(blkif, PAGE_SIZE *
> (info)->nr_ring_pages)
> > +#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
> > + * characters are enough. Define to 20 to keep consist with backend.
> > + */
> > +#define RINGREF_NAME_LEN (20)
> >
> > /*
> > * We have one of these per vbd, whether ide, scsi or 'other'. They
> > @@ -114,13 +128,14 @@ struct blkfront_info
> > int vdevice;
> > blkif_vdev_t handle;
> > enum blkif_state connected;
> > - int ring_ref;
> > + int ring_ref[XENBUS_MAX_RING_PAGES];
> > + unsigned int nr_ring_pages;
> > struct blkif_front_ring ring;
> > 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[BLK_MAX_RING_SIZE];
> > struct list_head grants;
> > struct list_head indirect_pages;
> > unsigned int persistent_gnts_c;
> > @@ -139,8 +154,6 @@ static unsigned int nr_minors;
> > static unsigned long *minors;
> > static DEFINE_SPINLOCK(minor_lock);
> >
> > -#define MAXIMUM_OUTSTANDING_BLOCK_REQS \
> > - (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
> > #define GRANT_INVALID_REF 0
> >
> > #define PARTS_PER_DISK 16
> > @@ -170,7 +183,7 @@ static int blkfront_setup_indirect(struct
> blkfront_info *info);
> > 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 >= BLK_RING_SIZE(info));
> > info->shadow_free = info->shadow[free].req.u.rw.id;
> > info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
> > return free;
> > @@ -983,7 +996,7 @@ static void blkif_free(struct blkfront_info *info, int
> suspend)
> > }
> > }
> >
> > - for (i = 0; i < BLK_RING_SIZE; i++) {
> > + for (i = 0; i < BLK_RING_SIZE(info); i++) {
> > /*
> > * Clear persistent grants present in requests already
> > * on the shared ring
> > @@ -1033,12 +1046,15 @@ free_shadow:
> > flush_work(&info->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 < info->nr_ring_pages; i++) {
> > + if (info->ring_ref[i] != GRANT_INVALID_REF) {
> > + gnttab_end_foreign_access(info->ring_ref[i], 0, 0);
> > + info->ring_ref[i] = GRANT_INVALID_REF;
> > + }
> > }
> > + free_pages((unsigned long)info->ring.sring, get_order(info-
> >nr_ring_pages * PAGE_SIZE));
> > + info->ring.sring = NULL;
> > +
> > if (info->irq)
> > unbind_from_irqhandler(info->irq, info);
> > info->evtchn = info->irq = 0;
> > @@ -1157,7 +1173,7 @@ static irqreturn_t blkif_interrupt(int irq, void
> *dev_id)
> > * never have given to it (we stamp it up to BLK_RING_SIZE -
> > * look in get_id_from_freelist.
> > */
> > - if (id >= BLK_RING_SIZE) {
> > + if (id >= BLK_RING_SIZE(info)) {
> > WARN(1, "%s: response to %s has incorrect id
> (%ld)\n",
> > info->gd->disk_name, op_name(bret->operation),
> id);
> > /* We can't safely get the 'struct request' as
> > @@ -1245,26 +1261,30 @@ static int setup_blkring(struct xenbus_device
> *dev,
> > struct blkfront_info *info)
> > {
> > struct blkif_sring *sring;
> > - grant_ref_t gref;
> > - int err;
> > + int err, i;
> > + unsigned long ring_size = info->nr_ring_pages * PAGE_SIZE;
> > + grant_ref_t gref[XENBUS_MAX_RING_PAGES];
> >
> > - info->ring_ref = GRANT_INVALID_REF;
> > + for (i = 0; i < info->nr_ring_pages; i++)
> > + info->ring_ref[i] = GRANT_INVALID_REF;
> >
> > - sring = (struct blkif_sring *)__get_free_page(GFP_NOIO |
> __GFP_HIGH);
> > + sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO |
> __GFP_HIGH,
> > + get_order(ring_size));
> > if (!sring) {
> > xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
> > return -ENOMEM;
> > }
> > SHARED_RING_INIT(sring);
> > - FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
> > + FRONT_RING_INIT(&info->ring, sring, ring_size);
> >
> > - err = xenbus_grant_ring(dev, info->ring.sring, 1, &gref);
> > + err = xenbus_grant_ring(dev, info->ring.sring, info->nr_ring_pages,
> gref);
> > if (err < 0) {
> > - free_page((unsigned long)sring);
> > + free_pages((unsigned long)sring, get_order(ring_size));
> > info->ring.sring = NULL;
> > goto fail;
> > }
> > - info->ring_ref = gref;
> > + for (i = 0; i < info->nr_ring_pages; i++)
> > + info->ring_ref[i] = gref[i];
> >
> > err = xenbus_alloc_evtchn(dev, &info->evtchn);
> > if (err)
> > @@ -1292,7 +1312,18 @@ static int talk_to_blkback(struct xenbus_device
> *dev,
> > {
> > const char *message = NULL;
> > struct xenbus_transaction xbt;
> > - int err;
> > + int err, i;
> > + unsigned int max_page_order = 0;
> > + unsigned int ring_page_order = 0;
> > +
> > + err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> > + "max-ring-page-order", "%u", &max_page_order);
> > + if (err != 1)
> > + info->nr_ring_pages = 1;
> > + else {
> > + ring_page_order = min(xen_blkif_max_ring_order,
> max_page_order);
> > + info->nr_ring_pages = 1 << ring_page_order;
> > + }
> >
> > /* Create shared ring, alloc event channel. */
> > err = setup_blkring(dev, info);
> > @@ -1306,11 +1337,32 @@ 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 (info->nr_ring_pages == 1) {
> > + err = xenbus_printf(xbt, dev->nodename,
> > + "ring-ref", "%u", info->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 < info->nr_ring_pages; 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", info->ring_ref[i]);
> > + if (err) {
> > + message = "writing ring-ref";
> > + goto abort_transaction;
> > + }
> > + }
> > }
> > err = xenbus_printf(xbt, dev->nodename,
> > "event-channel", "%u", info->evtchn);
> > @@ -1338,6 +1390,9 @@ again:
> > goto destroy_blkring;
> > }
> >
> > + for (i = 0; i < BLK_RING_SIZE(info); i++)
> > + info->shadow[i].req.u.rw.id = i+1;
> > + info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
> > xenbus_switch_state(dev, XenbusStateInitialised);
> >
> > return 0;
> > @@ -1361,7 +1416,7 @@ again:
> > static int blkfront_probe(struct xenbus_device *dev,
> > const struct xenbus_device_id *id)
> > {
> > - int err, vdevice, i;
> > + int err, vdevice;
> > struct blkfront_info *info;
> >
> > /* FIXME: Use dynamic device id if this is not set. */
> > @@ -1422,10 +1477,6 @@ 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++)
> > - 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);
> > dev_set_drvdata(&dev->dev, info);
> > @@ -1469,10 +1520,10 @@ 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 < BLK_RING_SIZE(info); i++)
> > info->shadow[i].req.u.rw.id = i+1;
> > info->shadow_free = info->ring.req_prod_pvt;
> > - info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
> > + info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
> >
> > rc = blkfront_setup_indirect(info);
> > if (rc) {
> > @@ -1484,7 +1535,7 @@ static int blkif_recover(struct blkfront_info *info)
> > blk_queue_max_segments(info->rq, segs);
> > bio_list_init(&bio_list);
> > INIT_LIST_HEAD(&requests);
> > - for (i = 0; i < BLK_RING_SIZE; i++) {
> > + for (i = 0; i < BLK_RING_SIZE(info); i++) {
> > /* Not in use? */
> > if (!copy[i].request)
> > continue;
> > @@ -1690,7 +1741,7 @@ static int blkfront_setup_indirect(struct
> blkfront_info *info)
> > segs = info->max_indirect_segments;
> > }
> >
> > - err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) *
> BLK_RING_SIZE);
> > + err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) *
> BLK_RING_SIZE(info));
> > if (err)
> > goto out_of_memory;
> >
> > @@ -1700,7 +1751,7 @@ static int blkfront_setup_indirect(struct
> blkfront_info *info)
> > * grants, we need to allocate a set of pages that can be
> > * used for mapping indirect grefs
> > */
> > - int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE;
> > + int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE(info);
> >
> > BUG_ON(!list_empty(&info->indirect_pages));
> > for (i = 0; i < num; i++) {
> > @@ -1711,7 +1762,7 @@ static int blkfront_setup_indirect(struct
> blkfront_info *info)
> > }
> > }
> >
> > - for (i = 0; i < BLK_RING_SIZE; i++) {
> > + for (i = 0; i < BLK_RING_SIZE(info); i++) {
> > info->shadow[i].grants_used = kzalloc(
> > sizeof(info->shadow[i].grants_used[0]) * segs,
> > GFP_NOIO);
> > @@ -1733,7 +1784,7 @@ static int blkfront_setup_indirect(struct
> blkfront_info *info)
> > return 0;
> >
> > out_of_memory:
> > - for (i = 0; i < BLK_RING_SIZE; i++) {
> > + for (i = 0; i < BLK_RING_SIZE(info); i++) {
> > kfree(info->shadow[i].grants_used);
> > info->shadow[i].grants_used = NULL;
> > kfree(info->shadow[i].sg);
> > @@ -2089,6 +2140,12 @@ static int __init xlblk_init(void)
> > if (!xen_domain())
> > return -ENODEV;
> >
> > + if (xen_blkif_max_ring_order > XENBUS_MAX_RING_PAGE_ORDER)
> {
> > + pr_info("Invalid max_ring_order (%d), will use default max:
> %d.\n",
> > + xen_blkif_max_ring_order,
> XENBUS_MAX_RING_PAGE_ORDER);
> > + xen_blkif_max_ring_order = 0;
> > + }
> > +
> > if (!xen_has_pv_disk_devices())
> > return -ENODEV;
> >
> >
--
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