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authorTejun Heo <tj@kernel.org>2014-09-24 13:00:21 -0400
committerTejun Heo <tj@kernel.org>2014-09-24 13:00:21 -0400
commitd06efebf0c37d438fcf07057be00dd40fcfce08d (patch)
tree31a0786d132aadf4cbb9725f3f444ef6e1052128 /block/blk-mq.c
parentbb2e226b3bef596dd56be97df655d857b4603923 (diff)
parent0a30288da1aec914e158c2d7a3482a85f632750f (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block into for-3.18
This is to receive 0a30288da1ae ("blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe") which implements __percpu_ref_kill_expedited() to work around SCSI blk-mq stall. The commit reverted and patches to implement proper fix will be added. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'block/blk-mq.c')
-rw-r--r--block/blk-mq.c162
1 files changed, 119 insertions, 43 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 702df07b980d..255d79c14dc1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -112,18 +112,31 @@ static void blk_mq_usage_counter_release(struct percpu_ref *ref)
*/
void blk_mq_freeze_queue(struct request_queue *q)
{
+ bool freeze;
+
spin_lock_irq(q->queue_lock);
- q->mq_freeze_depth++;
+ freeze = !q->mq_freeze_depth++;
spin_unlock_irq(q->queue_lock);
- percpu_ref_kill(&q->mq_usage_counter);
- blk_mq_run_queues(q, false);
+ if (freeze) {
+ /*
+ * XXX: Temporary kludge to work around SCSI blk-mq stall.
+ * SCSI synchronously creates and destroys many queues
+ * back-to-back during probe leading to lengthy stalls.
+ * This will be fixed by keeping ->mq_usage_counter in
+ * atomic mode until genhd registration, but, for now,
+ * let's work around using expedited synchronization.
+ */
+ __percpu_ref_kill_expedited(&q->mq_usage_counter);
+
+ blk_mq_run_queues(q, false);
+ }
wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter));
}
static void blk_mq_unfreeze_queue(struct request_queue *q)
{
- bool wake = false;
+ bool wake;
spin_lock_irq(q->queue_lock);
wake = !--q->mq_freeze_depth;
@@ -172,6 +185,8 @@ static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
/* tag was already set */
rq->errors = 0;
+ rq->cmd = rq->__cmd;
+
rq->extra_len = 0;
rq->sense_len = 0;
rq->resid_len = 0;
@@ -197,7 +212,6 @@ __blk_mq_alloc_request(struct blk_mq_alloc_data *data, int rw)
if (tag != BLK_MQ_TAG_FAIL) {
rq = data->hctx->tags->rqs[tag];
- rq->cmd_flags = 0;
if (blk_mq_tag_busy(data->hctx)) {
rq->cmd_flags = REQ_MQ_INFLIGHT;
atomic_inc(&data->hctx->nr_active);
@@ -252,6 +266,7 @@ static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
if (rq->cmd_flags & REQ_MQ_INFLIGHT)
atomic_dec(&hctx->nr_active);
+ rq->cmd_flags = 0;
clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
blk_mq_put_tag(hctx, tag, &ctx->last_tag);
@@ -387,6 +402,12 @@ static void blk_mq_start_request(struct request *rq, bool last)
blk_add_timer(rq);
/*
+ * Ensure that ->deadline is visible before set the started
+ * flag and clear the completed flag.
+ */
+ smp_mb__before_atomic();
+
+ /*
* Mark us as started and clear complete. Complete might have been
* set if requeue raced with timeout, which then marked it as
* complete. So be sure to clear complete again when we start
@@ -467,7 +488,11 @@ static void blk_mq_requeue_work(struct work_struct *work)
blk_mq_insert_request(rq, false, false, false);
}
- blk_mq_run_queues(q, false);
+ /*
+ * Use the start variant of queue running here, so that running
+ * the requeue work will kick stopped queues.
+ */
+ blk_mq_start_hw_queues(q);
}
void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
@@ -951,14 +976,9 @@ void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
hctx = q->mq_ops->map_queue(q, ctx->cpu);
- if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA) &&
- !(rq->cmd_flags & (REQ_FLUSH_SEQ))) {
- blk_insert_flush(rq);
- } else {
- spin_lock(&ctx->lock);
- __blk_mq_insert_request(hctx, rq, at_head);
- spin_unlock(&ctx->lock);
- }
+ spin_lock(&ctx->lock);
+ __blk_mq_insert_request(hctx, rq, at_head);
+ spin_unlock(&ctx->lock);
if (run_queue)
blk_mq_run_hw_queue(hctx, async);
@@ -1068,13 +1088,17 @@ static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
blk_account_io_start(rq, 1);
}
+static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
+{
+ return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
+ !blk_queue_nomerges(hctx->queue);
+}
+
static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx,
struct request *rq, struct bio *bio)
{
- struct request_queue *q = hctx->queue;
-
- if (!(hctx->flags & BLK_MQ_F_SHOULD_MERGE)) {
+ if (!hctx_allow_merges(hctx)) {
blk_mq_bio_to_request(rq, bio);
spin_lock(&ctx->lock);
insert_rq:
@@ -1082,6 +1106,8 @@ insert_rq:
spin_unlock(&ctx->lock);
return false;
} else {
+ struct request_queue *q = hctx->queue;
+
spin_lock(&ctx->lock);
if (!blk_mq_attempt_merge(q, ctx, bio)) {
blk_mq_bio_to_request(rq, bio);
@@ -1309,6 +1335,7 @@ static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
continue;
set->ops->exit_request(set->driver_data, tags->rqs[i],
hctx_idx, i);
+ tags->rqs[i] = NULL;
}
}
@@ -1342,8 +1369,9 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
INIT_LIST_HEAD(&tags->page_list);
- tags->rqs = kmalloc_node(set->queue_depth * sizeof(struct request *),
- GFP_KERNEL, set->numa_node);
+ tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
+ GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
+ set->numa_node);
if (!tags->rqs) {
blk_mq_free_tags(tags);
return NULL;
@@ -1367,8 +1395,9 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
this_order--;
do {
- page = alloc_pages_node(set->numa_node, GFP_KERNEL,
- this_order);
+ page = alloc_pages_node(set->numa_node,
+ GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
+ this_order);
if (page)
break;
if (!this_order--)
@@ -1389,11 +1418,15 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
left -= to_do * rq_size;
for (j = 0; j < to_do; j++) {
tags->rqs[i] = p;
+ tags->rqs[i]->atomic_flags = 0;
+ tags->rqs[i]->cmd_flags = 0;
if (set->ops->init_request) {
if (set->ops->init_request(set->driver_data,
tags->rqs[i], hctx_idx, i,
- set->numa_node))
+ set->numa_node)) {
+ tags->rqs[i] = NULL;
goto fail;
+ }
}
p += rq_size;
@@ -1404,7 +1437,6 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
return tags;
fail:
- pr_warn("%s: failed to allocate requests\n", __func__);
blk_mq_free_rq_map(set, tags, hctx_idx);
return NULL;
}
@@ -1574,7 +1606,7 @@ static int blk_mq_init_hw_queues(struct request_queue *q,
hctx->tags = set->tags[i];
/*
- * Allocate space for all possible cpus to avoid allocation in
+ * Allocate space for all possible cpus to avoid allocation at
* runtime
*/
hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
@@ -1662,8 +1694,8 @@ static void blk_mq_map_swqueue(struct request_queue *q)
queue_for_each_hw_ctx(q, hctx, i) {
/*
- * If not software queues are mapped to this hardware queue,
- * disable it and free the request entries
+ * If no software queues are mapped to this hardware queue,
+ * disable it and free the request entries.
*/
if (!hctx->nr_ctx) {
struct blk_mq_tag_set *set = q->tag_set;
@@ -1713,14 +1745,10 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q)
{
struct blk_mq_tag_set *set = q->tag_set;
- blk_mq_freeze_queue(q);
-
mutex_lock(&set->tag_list_lock);
list_del_init(&q->tag_set_list);
blk_mq_update_tag_set_depth(set);
mutex_unlock(&set->tag_list_lock);
-
- blk_mq_unfreeze_queue(q);
}
static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
@@ -1929,6 +1957,60 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
return NOTIFY_OK;
}
+static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
+{
+ int i;
+
+ for (i = 0; i < set->nr_hw_queues; i++) {
+ set->tags[i] = blk_mq_init_rq_map(set, i);
+ if (!set->tags[i])
+ goto out_unwind;
+ }
+
+ return 0;
+
+out_unwind:
+ while (--i >= 0)
+ blk_mq_free_rq_map(set, set->tags[i], i);
+
+ return -ENOMEM;
+}
+
+/*
+ * Allocate the request maps associated with this tag_set. Note that this
+ * may reduce the depth asked for, if memory is tight. set->queue_depth
+ * will be updated to reflect the allocated depth.
+ */
+static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
+{
+ unsigned int depth;
+ int err;
+
+ depth = set->queue_depth;
+ do {
+ err = __blk_mq_alloc_rq_maps(set);
+ if (!err)
+ break;
+
+ set->queue_depth >>= 1;
+ if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
+ err = -ENOMEM;
+ break;
+ }
+ } while (set->queue_depth);
+
+ if (!set->queue_depth || err) {
+ pr_err("blk-mq: failed to allocate request map\n");
+ return -ENOMEM;
+ }
+
+ if (depth != set->queue_depth)
+ pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
+ depth, set->queue_depth);
+
+ return 0;
+}
+
/*
* Alloc a tag set to be associated with one or more request queues.
* May fail with EINVAL for various error conditions. May adjust the
@@ -1937,8 +2019,6 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
*/
int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
{
- int i;
-
if (!set->nr_hw_queues)
return -EINVAL;
if (!set->queue_depth)
@@ -1959,23 +2039,18 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
sizeof(struct blk_mq_tags *),
GFP_KERNEL, set->numa_node);
if (!set->tags)
- goto out;
+ return -ENOMEM;
- for (i = 0; i < set->nr_hw_queues; i++) {
- set->tags[i] = blk_mq_init_rq_map(set, i);
- if (!set->tags[i])
- goto out_unwind;
- }
+ if (blk_mq_alloc_rq_maps(set))
+ goto enomem;
mutex_init(&set->tag_list_lock);
INIT_LIST_HEAD(&set->tag_list);
return 0;
-
-out_unwind:
- while (--i >= 0)
- blk_mq_free_rq_map(set, set->tags[i], i);
-out:
+enomem:
+ kfree(set->tags);
+ set->tags = NULL;
return -ENOMEM;
}
EXPORT_SYMBOL(blk_mq_alloc_tag_set);
@@ -1990,6 +2065,7 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
}
kfree(set->tags);
+ set->tags = NULL;
}
EXPORT_SYMBOL(blk_mq_free_tag_set);