xen/blkfront: split per device io_lock
After patch "xen/blkfront: separate per ring information out of device
info", per-ring data is protected by a per-device lock ('io_lock').
This is not a good way and will effect the scalability, so introduce a
per-ring lock ('ring_lock').
The old 'io_lock' is renamed to 'dev_lock' which protects the ->grants list and
->persistent_gnts_c which are shared by all rings.
Note that in 'blkfront_probe' the 'blkfront_info' is setup via kzalloc
so setting ->persistent_gnts_c to zero is not needed.
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Bob Liu
Konrad Rzeszutek Wilk
parent
3df0e50599
commit
11659569f7
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@ -125,6 +125,8 @@ MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the
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* depending on how many hardware queues/rings to be used.
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*/
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struct blkfront_ring_info {
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/* Lock to protect data in every ring buffer. */
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spinlock_t ring_lock;
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struct blkif_front_ring ring;
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unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
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unsigned int evtchn, irq;
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@ -143,7 +145,6 @@ struct blkfront_ring_info {
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*/
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struct blkfront_info
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{
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spinlock_t io_lock;
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struct mutex mutex;
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struct xenbus_device *xbdev;
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struct gendisk *gd;
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@ -153,6 +154,11 @@ struct blkfront_info
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/* Number of pages per ring buffer. */
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unsigned int nr_ring_pages;
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struct request_queue *rq;
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/*
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* Lock to protect info->grants list and persistent_gnts_c shared by all
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* rings.
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*/
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spinlock_t dev_lock;
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struct list_head grants;
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unsigned int persistent_gnts_c;
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unsigned int feature_flush;
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@ -258,7 +264,9 @@ static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
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}
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gnt_list_entry->gref = GRANT_INVALID_REF;
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spin_lock_irq(&info->dev_lock);
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list_add(&gnt_list_entry->node, &info->grants);
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spin_unlock_irq(&info->dev_lock);
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i++;
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}
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@ -267,7 +275,9 @@ static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
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out_of_memory:
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list_for_each_entry_safe(gnt_list_entry, n,
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&info->grants, node) {
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spin_lock_irq(&info->dev_lock);
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list_del(&gnt_list_entry->node);
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spin_unlock_irq(&info->dev_lock);
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if (info->feature_persistent)
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__free_page(gnt_list_entry->page);
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kfree(gnt_list_entry);
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@ -280,7 +290,9 @@ out_of_memory:
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static struct grant *get_free_grant(struct blkfront_info *info)
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{
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struct grant *gnt_list_entry;
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unsigned long flags;
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spin_lock_irqsave(&info->dev_lock, flags);
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BUG_ON(list_empty(&info->grants));
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gnt_list_entry = list_first_entry(&info->grants, struct grant,
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node);
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@ -288,6 +300,7 @@ static struct grant *get_free_grant(struct blkfront_info *info)
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if (gnt_list_entry->gref != GRANT_INVALID_REF)
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info->persistent_gnts_c--;
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spin_unlock_irqrestore(&info->dev_lock, flags);
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return gnt_list_entry;
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}
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@ -757,11 +770,11 @@ static inline bool blkif_request_flush_invalid(struct request *req,
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static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
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const struct blk_mq_queue_data *qd)
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{
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unsigned long flags;
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struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)hctx->driver_data;
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struct blkfront_info *info = rinfo->dev_info;
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blk_mq_start_request(qd->rq);
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spin_lock_irq(&info->io_lock);
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spin_lock_irqsave(&rinfo->ring_lock, flags);
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if (RING_FULL(&rinfo->ring))
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goto out_busy;
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@ -772,15 +785,15 @@ static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
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goto out_busy;
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flush_requests(rinfo);
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spin_unlock_irq(&info->io_lock);
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spin_unlock_irqrestore(&rinfo->ring_lock, flags);
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return BLK_MQ_RQ_QUEUE_OK;
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out_err:
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spin_unlock_irq(&info->io_lock);
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spin_unlock_irqrestore(&rinfo->ring_lock, flags);
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return BLK_MQ_RQ_QUEUE_ERROR;
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out_busy:
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spin_unlock_irq(&info->io_lock);
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spin_unlock_irqrestore(&rinfo->ring_lock, flags);
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blk_mq_stop_hw_queue(hctx);
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return BLK_MQ_RQ_QUEUE_BUSY;
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}
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@ -1082,21 +1095,28 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
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info->gd = NULL;
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}
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/* Must be called with io_lock holded */
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static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
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/* Already hold rinfo->ring_lock. */
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static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
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{
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if (!RING_FULL(&rinfo->ring))
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blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
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}
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static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
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{
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unsigned long flags;
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spin_lock_irqsave(&rinfo->ring_lock, flags);
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kick_pending_request_queues_locked(rinfo);
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spin_unlock_irqrestore(&rinfo->ring_lock, flags);
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}
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static void blkif_restart_queue(struct work_struct *work)
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{
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struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
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spin_lock_irq(&rinfo->dev_info->io_lock);
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if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
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kick_pending_request_queues(rinfo);
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spin_unlock_irq(&rinfo->dev_info->io_lock);
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}
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static void blkif_free_ring(struct blkfront_ring_info *rinfo)
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@ -1188,7 +1208,6 @@ static void blkif_free(struct blkfront_info *info, int suspend)
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unsigned int i;
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/* Prevent new requests being issued until we fix things up. */
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spin_lock_irq(&info->io_lock);
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info->connected = suspend ?
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BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
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/* No more blkif_request(). */
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@ -1196,6 +1215,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
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blk_mq_stop_hw_queues(info->rq);
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/* Remove all persistent grants */
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spin_lock_irq(&info->dev_lock);
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if (!list_empty(&info->grants)) {
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list_for_each_entry_safe(persistent_gnt, n,
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&info->grants, node) {
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@ -1211,6 +1231,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
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}
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}
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BUG_ON(info->persistent_gnts_c != 0);
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spin_unlock_irq(&info->dev_lock);
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for (i = 0; i < info->nr_rings; i++)
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blkif_free_ring(&info->rinfo[i]);
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@ -1218,7 +1239,6 @@ static void blkif_free(struct blkfront_info *info, int suspend)
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kfree(info->rinfo);
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info->rinfo = NULL;
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info->nr_rings = 0;
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spin_unlock_irq(&info->io_lock);
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}
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struct copy_from_grant {
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@ -1253,6 +1273,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
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int i = 0;
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struct scatterlist *sg;
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int num_sg, num_grant;
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unsigned long flags;
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struct blkfront_info *info = rinfo->dev_info;
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struct copy_from_grant data = {
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.s = s,
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@ -1291,8 +1312,10 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
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if (!info->feature_persistent)
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pr_alert_ratelimited("backed has not unmapped grant: %u\n",
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s->grants_used[i]->gref);
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spin_lock_irqsave(&info->dev_lock, flags);
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list_add(&s->grants_used[i]->node, &info->grants);
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info->persistent_gnts_c++;
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spin_unlock_irqrestore(&info->dev_lock, flags);
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} else {
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/*
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* If the grant is not mapped by the backend we end the
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@ -1302,7 +1325,9 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
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*/
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gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
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s->grants_used[i]->gref = GRANT_INVALID_REF;
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spin_lock_irqsave(&info->dev_lock, flags);
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list_add_tail(&s->grants_used[i]->node, &info->grants);
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spin_unlock_irqrestore(&info->dev_lock, flags);
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}
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}
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if (s->req.operation == BLKIF_OP_INDIRECT) {
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@ -1311,8 +1336,10 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
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if (!info->feature_persistent)
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pr_alert_ratelimited("backed has not unmapped grant: %u\n",
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s->indirect_grants[i]->gref);
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spin_lock_irqsave(&info->dev_lock, flags);
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list_add(&s->indirect_grants[i]->node, &info->grants);
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info->persistent_gnts_c++;
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spin_unlock_irqrestore(&info->dev_lock, flags);
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} else {
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struct page *indirect_page;
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@ -1326,7 +1353,9 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
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list_add(&indirect_page->lru, &rinfo->indirect_pages);
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}
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s->indirect_grants[i]->gref = GRANT_INVALID_REF;
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spin_lock_irqsave(&info->dev_lock, flags);
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list_add_tail(&s->indirect_grants[i]->node, &info->grants);
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spin_unlock_irqrestore(&info->dev_lock, flags);
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}
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}
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}
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@ -1342,13 +1371,10 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
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struct blkfront_info *info = rinfo->dev_info;
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int error;
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spin_lock_irqsave(&info->io_lock, flags);
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if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
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spin_unlock_irqrestore(&info->io_lock, flags);
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if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
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return IRQ_HANDLED;
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}
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spin_lock_irqsave(&rinfo->ring_lock, flags);
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again:
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rp = rinfo->ring.sring->rsp_prod;
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rmb(); /* Ensure we see queued responses up to 'rp'. */
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@ -1439,9 +1465,9 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
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} else
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rinfo->ring.sring->rsp_event = i + 1;
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kick_pending_request_queues(rinfo);
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kick_pending_request_queues_locked(rinfo);
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spin_unlock_irqrestore(&info->io_lock, flags);
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spin_unlock_irqrestore(&rinfo->ring_lock, flags);
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return IRQ_HANDLED;
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}
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@ -1690,14 +1716,14 @@ static int blkfront_probe(struct xenbus_device *dev,
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INIT_LIST_HEAD(&rinfo->indirect_pages);
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rinfo->dev_info = info;
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INIT_WORK(&rinfo->work, blkif_restart_queue);
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spin_lock_init(&rinfo->ring_lock);
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}
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mutex_init(&info->mutex);
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spin_lock_init(&info->io_lock);
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spin_lock_init(&info->dev_lock);
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info->xbdev = dev;
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info->vdevice = vdevice;
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INIT_LIST_HEAD(&info->grants);
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info->persistent_gnts_c = 0;
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info->connected = BLKIF_STATE_DISCONNECTED;
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/* Front end dir is a number, which is used as the id. */
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@ -1790,8 +1816,6 @@ static int blkif_recover(struct blkfront_info *info)
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}
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xenbus_switch_state(info->xbdev, XenbusStateConnected);
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spin_lock_irq(&info->io_lock);
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/* Now safe for us to use the shared ring */
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info->connected = BLKIF_STATE_CONNECTED;
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@ -1809,7 +1833,6 @@ static int blkif_recover(struct blkfront_info *info)
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BUG_ON(req->nr_phys_segments > segs);
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blk_mq_requeue_request(req);
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}
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spin_unlock_irq(&info->io_lock);
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blk_mq_kick_requeue_list(info->rq);
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while ((bio = bio_list_pop(&bio_list)) != NULL) {
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@ -2158,11 +2181,9 @@ static void blkfront_connect(struct blkfront_info *info)
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xenbus_switch_state(info->xbdev, XenbusStateConnected);
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/* Kick pending requests. */
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spin_lock_irq(&info->io_lock);
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info->connected = BLKIF_STATE_CONNECTED;
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for (i = 0; i < info->nr_rings; i++)
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kick_pending_request_queues(&info->rinfo[i]);
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spin_unlock_irq(&info->io_lock);
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add_disk(info->gd);
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