[PATCH 06/10] xen/blkfront: pseudo support for multi hardware queues

From: Bob Liu
Date: Sun Feb 15 2015 - 03:20:27 EST


Prepare patch for multi hardware queues, the ring number was mandatory set to 1.

Signed-off-by: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>
Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
drivers/block/xen-blkfront.c | 408 +++++++++++++++++++++++++------------------
1 file changed, 234 insertions(+), 174 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index aaa4a0e..d551be0 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -143,7 +143,8 @@ struct blkfront_info {
unsigned int max_indirect_segments;
int is_ready;
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;
@@ -176,7 +177,8 @@ static DEFINE_SPINLOCK(minor_lock);
#define INDIRECT_GREFS(_segs) \
((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)

-static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
+static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo, unsigned int segs);
+static int blkfront_gather_indirect(struct blkfront_info *info);

static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
{
@@ -656,7 +658,7 @@ static int blk_mq_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
{
struct blkfront_info *info = (struct blkfront_info *)data;

- hctx->driver_data = &info->rinfo;
+ hctx->driver_data = &info->rinfo[index];
return 0;
}

@@ -915,8 +917,8 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,

static void xlvbd_release_gendisk(struct blkfront_info *info)
{
- unsigned int minor, nr_minors;
- struct blkfront_ring_info *rinfo = &info->rinfo;
+ unsigned int minor, nr_minors, i;
+ struct blkfront_ring_info *rinfo;

if (info->rq == NULL)
return;
@@ -924,11 +926,14 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
/* No more blkif_request(). */
blk_mq_stop_hw_queues(info->rq);

- /* No more gnttab callback work. */
- gnttab_cancel_free_callback(&rinfo->callback);
+ for (i = 0; i < info->nr_rings; i++) {
+ rinfo = &info->rinfo[i];
+ /* 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);
+ /* Flush gnttab callback work. Must be done with no locks held. */
+ flush_work(&rinfo->work);
+ }

del_gendisk(info->gd);

@@ -969,8 +974,8 @@ static void blkif_free(struct blkfront_info *info, int suspend)
{
struct grant *persistent_gnt;
struct grant *n;
- int i, j, segs;
- struct blkfront_ring_info *rinfo = &info->rinfo;
+ int i, j, segs, rindex;
+ struct blkfront_ring_info *rinfo;

/* Prevent new requests being issued until we fix things up. */
info->connected = suspend ?
@@ -979,97 +984,100 @@ static void blkif_free(struct blkfront_info *info, int suspend)
if (info->rq)
blk_mq_stop_hw_queues(info->rq);

- spin_lock_irq(&rinfo->io_lock);
- /* 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 (rindex = 0; rindex < info->nr_rings; rindex++) {
+ rinfo = &info->rinfo[rindex];
+ spin_lock_irq(&rinfo->io_lock);
+ /* 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 (info->feature_persistent)
+ __free_page(pfn_to_page(persistent_gnt->pfn));
+ kfree(persistent_gnt);
}
- if (info->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(info->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; 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 (info->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(info->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; 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 (info->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(&rinfo->io_lock);
+ /* No more gnttab callback work. */
+ gnttab_cancel_free_callback(&rinfo->callback);
+ spin_unlock_irq(&rinfo->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. */
- if (rinfo->ring_ref != GRANT_INVALID_REF) {
- gnttab_end_foreign_access(rinfo->ring_ref, 0,
- (unsigned long)rinfo->ring.sring);
- rinfo->ring_ref = GRANT_INVALID_REF;
- rinfo->ring.sring = NULL;
+ /* Free resources associated with old device channel. */
+ if (rinfo->ring_ref != GRANT_INVALID_REF) {
+ gnttab_end_foreign_access(rinfo->ring_ref, 0,
+ (unsigned long)rinfo->ring.sring);
+ rinfo->ring_ref = GRANT_INVALID_REF;
+ rinfo->ring.sring = NULL;
+ }
+ if (rinfo->irq)
+ unbind_from_irqhandler(rinfo->irq, rinfo);
+ rinfo->evtchn = rinfo->irq = 0;
}
- if (rinfo->irq)
- unbind_from_irqhandler(rinfo->irq, rinfo);
- rinfo->evtchn = rinfo->irq = 0;

}

@@ -1265,6 +1273,18 @@ 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)
+{
+ if (rinfo->irq)
+ unbind_from_irqhandler(rinfo->irq, rinfo);
+ if (rinfo->evtchn)
+ xenbus_free_evtchn(dev, rinfo->evtchn);
+ if (rinfo->ring_ref != GRANT_INVALID_REF)
+ gnttab_end_foreign_access(rinfo->ring_ref, 0, (unsigned long)rinfo->ring.sring);
+ if (rinfo->ring.sring)
+ free_page((unsigned long)rinfo->ring.sring);
+}

static int setup_blkring(struct xenbus_device *dev,
struct blkfront_ring_info *rinfo)
@@ -1305,7 +1325,7 @@ static int setup_blkring(struct xenbus_device *dev,

return 0;
fail:
- blkif_free(rinfo->info, 0);
+ destroy_blkring(dev, rinfo);
return err;
}

@@ -1316,31 +1336,40 @@ static int talk_to_blkback(struct xenbus_device *dev,
{
const char *message = NULL;
struct xenbus_transaction xbt;
- int err;
- struct blkfront_ring_info *rinfo = &info->rinfo;
+ int err, i;
+ struct blkfront_ring_info *rinfo;

- /* Create shared ring, alloc event channel. */
- err = setup_blkring(dev, rinfo);
- if (err)
- goto out;
+ for (i = 0; i < info->nr_rings; i++) {
+ rinfo = &info->rinfo[i];
+ /* 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;
}

- err = xenbus_printf(xbt, dev->nodename,
- "ring-ref", "%u", rinfo->ring_ref);
- 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";
+ if (info->nr_rings == 1) {
+ rinfo = &info->rinfo[0];
+ err = xenbus_printf(xbt, dev->nodename,
+ "ring-ref", "%u", rinfo->ring_ref);
+ 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";
+ goto abort_transaction;
+ }
+ } else {
+ /* Not supported at this stage */
goto abort_transaction;
}
err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
@@ -1360,7 +1389,7 @@ again:
if (err == -EAGAIN)
goto again;
xenbus_dev_fatal(dev, err, "completing transaction");
- goto destroy_blkring;
+ goto out;
}

xenbus_switch_state(dev, XenbusStateInitialised);
@@ -1371,9 +1400,11 @@ again:
xenbus_transaction_end(xbt, 1);
if (message)
xenbus_dev_fatal(dev, err, "%s", message);
- destroy_blkring:
- blkif_free(info, 0);
out:
+ while (--i >= 0) {
+ rinfo = &info->rinfo[i];
+ destroy_blkring(dev, rinfo);
+ }
return err;
}

@@ -1386,7 +1417,7 @@ again:
static int blkfront_probe(struct xenbus_device *dev,
const struct xenbus_device_id *id)
{
- int err, vdevice, i;
+ int err, vdevice, i, rindex;
struct blkfront_info *info;
struct blkfront_ring_info *rinfo;

@@ -1437,22 +1468,32 @@ static int blkfront_probe(struct xenbus_device *dev,
xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
return -ENOMEM;
}
-
- rinfo = &info->rinfo;
mutex_init(&info->mutex);
- spin_lock_init(&rinfo->io_lock);
info->xbdev = dev;
info->vdevice = vdevice;
- INIT_LIST_HEAD(&rinfo->grants);
- INIT_LIST_HEAD(&rinfo->indirect_pages);
- rinfo->persistent_gnts_c = 0;
info->connected = BLKIF_STATE_DISCONNECTED;
- rinfo->info = info;
- INIT_WORK(&rinfo->work, blkif_restart_queue);

- for (i = 0; i < BLK_RING_SIZE; i++)
- rinfo->shadow[i].req.u.rw.id = i+1;
- rinfo->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
+ info->nr_rings = 1;
+ info->rinfo = kzalloc(sizeof(*rinfo) * info->nr_rings, GFP_KERNEL);
+ if (!info->rinfo) {
+ xenbus_dev_fatal(dev, -ENOMEM, "allocating ring_info structure");
+ kfree(info);
+ return -ENOMEM;
+ }
+
+ for (rindex = 0; rindex < info->nr_rings; rindex++) {
+ rinfo = &info->rinfo[rindex];
+ spin_lock_init(&rinfo->io_lock);
+ INIT_LIST_HEAD(&rinfo->grants);
+ INIT_LIST_HEAD(&rinfo->indirect_pages);
+ rinfo->persistent_gnts_c = 0;
+ rinfo->info = info;
+ INIT_WORK(&rinfo->work, blkif_restart_queue);
+
+ for (i = 0; i < BLK_RING_SIZE; i++)
+ rinfo->shadow[i].req.u.rw.id = i+1;
+ rinfo->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);
@@ -1485,7 +1526,7 @@ static void split_bio_end(struct bio *bio, int error)

static int blkif_recover(struct blkfront_info *info)
{
- int i;
+ int i, rindex;
struct request *req, *n;
struct blk_shadow *copy;
int rc;
@@ -1495,64 +1536,70 @@ static int blkif_recover(struct blkfront_info *info)
int pending, size;
struct split_bio *split_bio;
struct list_head requests;
- struct blkfront_ring_info *rinfo = &info->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; i++)
- rinfo->shadow[i].req.u.rw.id = i+1;
- rinfo->shadow_free = rinfo->ring.req_prod_pvt;
- rinfo->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
-
- rc = blkfront_setup_indirect(rinfo);
- if (rc) {
- kfree(copy);
- return rc;
- }
+ struct blkfront_ring_info *rinfo;

- segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
+ segs = blkfront_gather_indirect(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++) {
- /* Not in use? */
- if (!copy[i].request)
- continue;
+ for (rindex = 0; rindex < info->nr_rings; rindex++) {
+ rinfo = &info->rinfo[rindex];
+ /* 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; i++)
+ rinfo->shadow[i].req.u.rw.id = i+1;
+ rinfo->shadow_free = rinfo->ring.req_prod_pvt;
+ rinfo->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
+
+ rc = blkfront_setup_indirect(rinfo, segs);
+ if (rc) {
+ kfree(copy);
+ return rc;
+ }
+
+ for (i = 0; i < BLK_RING_SIZE; 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)) {
/*
- * 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_put_request(copy[i].request);
}
- 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_put_request(copy[i].request);
- }

- kfree(copy);
+ kfree(copy);
+ }

xenbus_switch_state(info->xbdev, XenbusStateConnected);

/* Now safe for us to use the shared ring */
info->connected = BLKIF_STATE_CONNECTED;

- /* Kick any other new requests queued since we resumed */
- kick_pending_request_queues(rinfo);
+ for (rindex = 0; rindex < info->nr_rings; rindex++) {
+ rinfo = &info->rinfo[rindex];
+ /* 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) */
@@ -1685,11 +1732,10 @@ static void blkfront_setup_discard(struct blkfront_info *info)
info->feature_secdiscard = !!discard_secure;
}

-static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
+static int blkfront_gather_indirect(struct blkfront_info *info)
{
unsigned int indirect_segments, segs;
- int err, i;
- struct blkfront_info *info = rinfo->info;
+ int err;

err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
"feature-max-indirect-segments", "%u", &indirect_segments,
@@ -1702,6 +1748,13 @@ static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
xen_blkif_max_segments);
segs = info->max_indirect_segments;
}
+ return segs;
+}
+
+static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo, unsigned int segs)
+{
+ int err, i;
+ struct blkfront_info *info = rinfo->info;

err = fill_grant_buffer(rinfo, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE);
if (err)
@@ -1774,9 +1827,9 @@ static void blkfront_connect(struct blkfront_info *info)
unsigned long sector_size;
unsigned int physical_sector_size;
unsigned int binfo;
- int err;
+ int err, i;
int barrier, flush, discard, persistent;
- struct blkfront_ring_info *rinfo = &info->rinfo;
+ struct blkfront_ring_info *rinfo;

switch (info->connected) {
case BLKIF_STATE_CONNECTED:
@@ -1874,11 +1927,15 @@ static void blkfront_connect(struct blkfront_info *info)
else
info->feature_persistent = persistent;

- err = blkfront_setup_indirect(rinfo);
- if (err) {
- xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
- info->xbdev->otherend);
- return;
+ for (i = 0; i < info->nr_rings; i++) {
+ rinfo = &info->rinfo[i];
+ err = blkfront_setup_indirect(rinfo, blkfront_gather_indirect(info));
+ if (err) {
+ xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
+ info->xbdev->otherend);
+ blkif_free(info, 0);
+ return;
+ }
}

err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
@@ -1893,7 +1950,10 @@ static void blkfront_connect(struct blkfront_info *info)

/* Kick pending requests. */
info->connected = BLKIF_STATE_CONNECTED;
- kick_pending_request_queues(rinfo);
+ for (i = 0; i < info->nr_rings; i++) {
+ rinfo = &info->rinfo[i];
+ kick_pending_request_queues(rinfo);
+ }

add_disk(info->gd);

--
1.8.3.1

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