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authorLinus Torvalds <torvalds@linux-foundation.org>2017-06-21 22:15:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-06-21 22:15:00 -0700
commit8d829b9bb878904f3419af8003176a12910b94e8 (patch)
treea038a1914059c4caf7849caeb967ddb4df818e4a
parent48b6bbef9a1789f0365c1a385879a1fea4460016 (diff)
parent8e8320c9315c47a6a090188720ccff32a6a6ba18 (diff)
downloadlinux-sh-8d829b9bb878904f3419af8003176a12910b94e8.tar.gz
Merge branch 'for-linus' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe: "This contains a set of fixes for xen-blkback by way of Konrad, and a performance regression fix for blk-mq for shared tags. The latter could account for as much as a 50x reduction in performance, with the test case from the user with 500 name spaces. A more realistic setup on my end with 32 drives showed a 3.5x drop. The fix has been thoroughly tested before being committed" * 'for-linus' of git://git.kernel.dk/linux-block: blk-mq: fix performance regression with shared tags xen-blkback: don't leak stack data via response ring xen/blkback: don't use xen_blkif_get() in xen-blkback kthread xen/blkback: don't free be structure too early xen/blkback: fix disconnect while I/Os in flight
-rw-r--r--block/blk-mq-sched.c58
-rw-r--r--block/blk-mq-sched.h9
-rw-r--r--block/blk-mq.c16
-rw-r--r--drivers/block/xen-blkback/blkback.c26
-rw-r--r--drivers/block/xen-blkback/common.h26
-rw-r--r--drivers/block/xen-blkback/xenbus.c15
-rw-r--r--include/linux/blkdev.h2
7 files changed, 87 insertions, 65 deletions
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 1f5b692526ae..0ded5e846335 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -68,6 +68,45 @@ static void blk_mq_sched_assign_ioc(struct request_queue *q,
__blk_mq_sched_assign_ioc(q, rq, bio, ioc);
}
+/*
+ * Mark a hardware queue as needing a restart. For shared queues, maintain
+ * a count of how many hardware queues are marked for restart.
+ */
+static void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx)
+{
+ if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
+ return;
+
+ if (hctx->flags & BLK_MQ_F_TAG_SHARED) {
+ struct request_queue *q = hctx->queue;
+
+ if (!test_and_set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
+ atomic_inc(&q->shared_hctx_restart);
+ } else
+ set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
+}
+
+static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
+{
+ if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
+ return false;
+
+ if (hctx->flags & BLK_MQ_F_TAG_SHARED) {
+ struct request_queue *q = hctx->queue;
+
+ if (test_and_clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
+ atomic_dec(&q->shared_hctx_restart);
+ } else
+ clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
+
+ if (blk_mq_hctx_has_pending(hctx)) {
+ blk_mq_run_hw_queue(hctx, true);
+ return true;
+ }
+
+ return false;
+}
+
struct request *blk_mq_sched_get_request(struct request_queue *q,
struct bio *bio,
unsigned int op,
@@ -266,18 +305,6 @@ static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
return true;
}
-static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
-{
- if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
- clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
- if (blk_mq_hctx_has_pending(hctx)) {
- blk_mq_run_hw_queue(hctx, true);
- return true;
- }
- }
- return false;
-}
-
/**
* list_for_each_entry_rcu_rr - iterate in a round-robin fashion over rcu list
* @pos: loop cursor.
@@ -309,6 +336,13 @@ void blk_mq_sched_restart(struct blk_mq_hw_ctx *const hctx)
unsigned int i, j;
if (set->flags & BLK_MQ_F_TAG_SHARED) {
+ /*
+ * If this is 0, then we know that no hardware queues
+ * have RESTART marked. We're done.
+ */
+ if (!atomic_read(&queue->shared_hctx_restart))
+ return;
+
rcu_read_lock();
list_for_each_entry_rcu_rr(q, queue, &set->tag_list,
tag_set_list) {
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index edafb5383b7b..5007edece51a 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -115,15 +115,6 @@ static inline bool blk_mq_sched_has_work(struct blk_mq_hw_ctx *hctx)
return false;
}
-/*
- * Mark a hardware queue as needing a restart.
- */
-static inline void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx)
-{
- if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
- set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
-}
-
static inline bool blk_mq_sched_needs_restart(struct blk_mq_hw_ctx *hctx)
{
return test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index bb66c96850b1..958cedaff8b8 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2103,20 +2103,30 @@ static void blk_mq_map_swqueue(struct request_queue *q,
}
}
+/*
+ * Caller needs to ensure that we're either frozen/quiesced, or that
+ * the queue isn't live yet.
+ */
static void queue_set_hctx_shared(struct request_queue *q, bool shared)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i) {
- if (shared)
+ if (shared) {
+ if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
+ atomic_inc(&q->shared_hctx_restart);
hctx->flags |= BLK_MQ_F_TAG_SHARED;
- else
+ } else {
+ if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
+ atomic_dec(&q->shared_hctx_restart);
hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
+ }
}
}
-static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
+static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set,
+ bool shared)
{
struct request_queue *q;
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 726c32e35db9..0e824091a12f 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -609,8 +609,6 @@ int xen_blkif_schedule(void *arg)
unsigned long timeout;
int ret;
- xen_blkif_get(blkif);
-
set_freezable();
while (!kthread_should_stop()) {
if (try_to_freeze())
@@ -665,7 +663,6 @@ purge_gnt_list:
print_stats(ring);
ring->xenblkd = NULL;
- xen_blkif_put(blkif);
return 0;
}
@@ -1436,34 +1433,35 @@ static int dispatch_rw_block_io(struct xen_blkif_ring *ring,
static void make_response(struct xen_blkif_ring *ring, u64 id,
unsigned short op, int st)
{
- struct blkif_response resp;
+ struct blkif_response *resp;
unsigned long flags;
union blkif_back_rings *blk_rings;
int notify;
- resp.id = id;
- resp.operation = op;
- resp.status = st;
-
spin_lock_irqsave(&ring->blk_ring_lock, flags);
blk_rings = &ring->blk_rings;
/* Place on the response ring for the relevant domain. */
switch (ring->blkif->blk_protocol) {
case BLKIF_PROTOCOL_NATIVE:
- memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt),
- &resp, sizeof(resp));
+ resp = RING_GET_RESPONSE(&blk_rings->native,
+ blk_rings->native.rsp_prod_pvt);
break;
case BLKIF_PROTOCOL_X86_32:
- memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt),
- &resp, sizeof(resp));
+ resp = RING_GET_RESPONSE(&blk_rings->x86_32,
+ blk_rings->x86_32.rsp_prod_pvt);
break;
case BLKIF_PROTOCOL_X86_64:
- memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt),
- &resp, sizeof(resp));
+ resp = RING_GET_RESPONSE(&blk_rings->x86_64,
+ blk_rings->x86_64.rsp_prod_pvt);
break;
default:
BUG();
}
+
+ resp->id = id;
+ resp->operation = op;
+ resp->status = st;
+
blk_rings->common.rsp_prod_pvt++;
RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
spin_unlock_irqrestore(&ring->blk_ring_lock, flags);
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index dea61f6ab8cb..ecb35fe8ca8d 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -75,9 +75,8 @@ extern unsigned int xenblk_max_queues;
struct blkif_common_request {
char dummy;
};
-struct blkif_common_response {
- char dummy;
-};
+
+/* i386 protocol version */
struct blkif_x86_32_request_rw {
uint8_t nr_segments; /* number of segments */
@@ -129,14 +128,6 @@ struct blkif_x86_32_request {
} u;
} __attribute__((__packed__));
-/* i386 protocol version */
-#pragma pack(push, 4)
-struct blkif_x86_32_response {
- uint64_t id; /* copied from request */
- uint8_t operation; /* copied from request */
- int16_t status; /* BLKIF_RSP_??? */
-};
-#pragma pack(pop)
/* x86_64 protocol version */
struct blkif_x86_64_request_rw {
@@ -193,18 +184,12 @@ struct blkif_x86_64_request {
} u;
} __attribute__((__packed__));
-struct blkif_x86_64_response {
- uint64_t __attribute__((__aligned__(8))) id;
- uint8_t operation; /* copied from request */
- int16_t status; /* BLKIF_RSP_??? */
-};
-
DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
- struct blkif_common_response);
+ struct blkif_response);
DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
- struct blkif_x86_32_response);
+ struct blkif_response __packed);
DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
- struct blkif_x86_64_response);
+ struct blkif_response);
union blkif_back_rings {
struct blkif_back_ring native;
@@ -281,6 +266,7 @@ struct xen_blkif_ring {
wait_queue_head_t wq;
atomic_t inflight;
+ bool active;
/* One thread per blkif ring. */
struct task_struct *xenblkd;
unsigned int waiting_reqs;
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 1f3dfaa54d87..792da683e70d 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -159,7 +159,7 @@ static int xen_blkif_alloc_rings(struct xen_blkif *blkif)
init_waitqueue_head(&ring->shutdown_wq);
ring->blkif = blkif;
ring->st_print = jiffies;
- xen_blkif_get(blkif);
+ ring->active = true;
}
return 0;
@@ -249,10 +249,12 @@ static int xen_blkif_disconnect(struct xen_blkif *blkif)
struct xen_blkif_ring *ring = &blkif->rings[r];
unsigned int i = 0;
+ if (!ring->active)
+ continue;
+
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
@@ -296,7 +298,7 @@ static int xen_blkif_disconnect(struct xen_blkif *blkif)
BUG_ON(ring->free_pages_num != 0);
BUG_ON(ring->persistent_gnt_c != 0);
WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
- xen_blkif_put(blkif);
+ ring->active = false;
}
blkif->nr_ring_pages = 0;
/*
@@ -312,9 +314,10 @@ static int xen_blkif_disconnect(struct xen_blkif *blkif)
static void xen_blkif_free(struct xen_blkif *blkif)
{
-
- xen_blkif_disconnect(blkif);
+ WARN_ON(xen_blkif_disconnect(blkif));
xen_vbd_free(&blkif->vbd);
+ kfree(blkif->be->mode);
+ kfree(blkif->be);
/* Make sure everything is drained before shutting down */
kmem_cache_free(xen_blkif_cachep, blkif);
@@ -511,8 +514,6 @@ static int xen_blkbk_remove(struct xenbus_device *dev)
xen_blkif_put(be->blkif);
}
- kfree(be->mode);
- kfree(be);
return 0;
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b74a3edcb3da..1ddd36bd2173 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -391,6 +391,8 @@ struct request_queue {
int nr_rqs[2]; /* # allocated [a]sync rqs */
int nr_rqs_elvpriv; /* # allocated rqs w/ elvpriv */
+ atomic_t shared_hctx_restart;
+
struct blk_queue_stats *stats;
struct rq_wb *rq_wb;