summaryrefslogtreecommitdiffstats
path: root/block
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2014-06-20 05:56:43 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-20 05:56:43 +0200
commitf1d702487b3bc16466ad9b4e5c76277b6829d34c (patch)
tree30398d00626a15477645cef81507808330f9439a /block
parentMerge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/... (diff)
parentblk-mq: bitmap tag: fix races in bt_get() function (diff)
downloadlinux-f1d702487b3bc16466ad9b4e5c76277b6829d34c.tar.xz
linux-f1d702487b3bc16466ad9b4e5c76277b6829d34c.zip
Merge branch 'for-linus' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe: "A smaller collection of fixes for the block core that would be nice to have in -rc2. This pull request contains: - Fixes for races in the wait/wakeup logic used in blk-mq from Alexander. No issues have been observed, but it is definitely a bit flakey currently. Alternatively, we may drop the cyclic wakeups going forward, but that needs more testing. - Some cleanups from Christoph. - Fix for an oops in null_blk if queue_mode=1 and softirq completions are used. From me. - A fix for a regression caused by the chunk size setting. It inadvertently used max_hw_sectors instead of max_sectors, which is incorrect, and causes hangs on btrfs multi-disk setups (where hw sectors apparently isn't set). From me. - Removal of WQ_POWER_EFFICIENT in the kblockd creation. This was a recent addition as well, but it actually breaks blk-mq which relies on strict scheduling. If the workqueue power_efficient mode is turned on, this breaks blk-mq. From Matias. - null_blk module parameter description fix from Mike" * 'for-linus' of git://git.kernel.dk/linux-block: blk-mq: bitmap tag: fix races in bt_get() function blk-mq: bitmap tag: fix race on blk_mq_bitmap_tags::wake_cnt blk-mq: bitmap tag: fix races on shared ::wake_index fields block: blk_max_size_offset() should check ->max_sectors null_blk: fix softirq completions for queue_mode == 1 blk-mq: merge blk_mq_drain_queue and __blk_mq_drain_queue blk-mq: properly drain stopped queues block: remove WQ_POWER_EFFICIENT from kblockd null_blk: fix name and description of 'queue_mode' module parameter block: remove elv_abort_queue and blk_abort_flushes
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c3
-rw-r--r--block/blk-flush.c38
-rw-r--r--block/blk-mq-tag.c59
-rw-r--r--block/blk-mq-tag.h2
-rw-r--r--block/blk-mq.c11
-rw-r--r--block/blk.h1
-rw-r--r--block/elevator.c20
7 files changed, 43 insertions, 91 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index f6f6b9af3e3f..6f8dba161bfe 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -3312,8 +3312,7 @@ int __init blk_dev_init(void)
/* used for unplugging and affects IO latency/throughput - HIGHPRI */
kblockd_workqueue = alloc_workqueue("kblockd",
- WQ_MEM_RECLAIM | WQ_HIGHPRI |
- WQ_POWER_EFFICIENT, 0);
+ WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
if (!kblockd_workqueue)
panic("Failed to create kblockd\n");
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 8ffee4b5f93d..3cb5e9e7108a 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -422,44 +422,6 @@ void blk_insert_flush(struct request *rq)
}
/**
- * blk_abort_flushes - @q is being aborted, abort flush requests
- * @q: request_queue being aborted
- *
- * To be called from elv_abort_queue(). @q is being aborted. Prepare all
- * FLUSH/FUA requests for abortion.
- *
- * CONTEXT:
- * spin_lock_irq(q->queue_lock)
- */
-void blk_abort_flushes(struct request_queue *q)
-{
- struct request *rq, *n;
- int i;
-
- /*
- * Requests in flight for data are already owned by the dispatch
- * queue or the device driver. Just restore for normal completion.
- */
- list_for_each_entry_safe(rq, n, &q->flush_data_in_flight, flush.list) {
- list_del_init(&rq->flush.list);
- blk_flush_restore_request(rq);
- }
-
- /*
- * We need to give away requests on flush queues. Restore for
- * normal completion and put them on the dispatch queue.
- */
- for (i = 0; i < ARRAY_SIZE(q->flush_queue); i++) {
- list_for_each_entry_safe(rq, n, &q->flush_queue[i],
- flush.list) {
- list_del_init(&rq->flush.list);
- blk_flush_restore_request(rq);
- list_add_tail(&rq->queuelist, &q->queue_head);
- }
- }
-}
-
-/**
* blkdev_issue_flush - queue a flush
* @bdev: blockdev to issue flush for
* @gfp_mask: memory allocation flags (for bio_alloc)
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 1aab39f71d95..c1b92426c95e 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -43,9 +43,16 @@ bool blk_mq_has_free_tags(struct blk_mq_tags *tags)
return bt_has_free_tags(&tags->bitmap_tags);
}
-static inline void bt_index_inc(unsigned int *index)
+static inline int bt_index_inc(int index)
{
- *index = (*index + 1) & (BT_WAIT_QUEUES - 1);
+ return (index + 1) & (BT_WAIT_QUEUES - 1);
+}
+
+static inline void bt_index_atomic_inc(atomic_t *index)
+{
+ int old = atomic_read(index);
+ int new = bt_index_inc(old);
+ atomic_cmpxchg(index, old, new);
}
/*
@@ -69,14 +76,14 @@ static void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags)
int i, wake_index;
bt = &tags->bitmap_tags;
- wake_index = bt->wake_index;
+ wake_index = atomic_read(&bt->wake_index);
for (i = 0; i < BT_WAIT_QUEUES; i++) {
struct bt_wait_state *bs = &bt->bs[wake_index];
if (waitqueue_active(&bs->wait))
wake_up(&bs->wait);
- bt_index_inc(&wake_index);
+ wake_index = bt_index_inc(wake_index);
}
}
@@ -212,12 +219,14 @@ static struct bt_wait_state *bt_wait_ptr(struct blk_mq_bitmap_tags *bt,
struct blk_mq_hw_ctx *hctx)
{
struct bt_wait_state *bs;
+ int wait_index;
if (!hctx)
return &bt->bs[0];
- bs = &bt->bs[hctx->wait_index];
- bt_index_inc(&hctx->wait_index);
+ wait_index = atomic_read(&hctx->wait_index);
+ bs = &bt->bs[wait_index];
+ bt_index_atomic_inc(&hctx->wait_index);
return bs;
}
@@ -239,18 +248,12 @@ static int bt_get(struct blk_mq_alloc_data *data,
bs = bt_wait_ptr(bt, hctx);
do {
- bool was_empty;
-
- was_empty = list_empty(&wait.task_list);
prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE);
tag = __bt_get(hctx, bt, last_tag);
if (tag != -1)
break;
- if (was_empty)
- atomic_set(&bs->wait_cnt, bt->wake_cnt);
-
blk_mq_put_ctx(data->ctx);
io_schedule();
@@ -313,18 +316,19 @@ static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt)
{
int i, wake_index;
- wake_index = bt->wake_index;
+ wake_index = atomic_read(&bt->wake_index);
for (i = 0; i < BT_WAIT_QUEUES; i++) {
struct bt_wait_state *bs = &bt->bs[wake_index];
if (waitqueue_active(&bs->wait)) {
- if (wake_index != bt->wake_index)
- bt->wake_index = wake_index;
+ int o = atomic_read(&bt->wake_index);
+ if (wake_index != o)
+ atomic_cmpxchg(&bt->wake_index, o, wake_index);
return bs;
}
- bt_index_inc(&wake_index);
+ wake_index = bt_index_inc(wake_index);
}
return NULL;
@@ -334,6 +338,7 @@ static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag)
{
const int index = TAG_TO_INDEX(bt, tag);
struct bt_wait_state *bs;
+ int wait_cnt;
/*
* The unlock memory barrier need to order access to req in free
@@ -342,10 +347,19 @@ static void bt_clear_tag(struct blk_mq_bitmap_tags *bt, unsigned int tag)
clear_bit_unlock(TAG_TO_BIT(bt, tag), &bt->map[index].word);
bs = bt_wake_ptr(bt);
- if (bs && atomic_dec_and_test(&bs->wait_cnt)) {
- atomic_set(&bs->wait_cnt, bt->wake_cnt);
- bt_index_inc(&bt->wake_index);
+ if (!bs)
+ return;
+
+ wait_cnt = atomic_dec_return(&bs->wait_cnt);
+ if (wait_cnt == 0) {
+wake:
+ atomic_add(bt->wake_cnt, &bs->wait_cnt);
+ bt_index_atomic_inc(&bt->wake_index);
wake_up(&bs->wait);
+ } else if (wait_cnt < 0) {
+ wait_cnt = atomic_inc_return(&bs->wait_cnt);
+ if (!wait_cnt)
+ goto wake;
}
}
@@ -499,10 +513,13 @@ static int bt_alloc(struct blk_mq_bitmap_tags *bt, unsigned int depth,
return -ENOMEM;
}
- for (i = 0; i < BT_WAIT_QUEUES; i++)
+ bt_update_count(bt, depth);
+
+ for (i = 0; i < BT_WAIT_QUEUES; i++) {
init_waitqueue_head(&bt->bs[i].wait);
+ atomic_set(&bt->bs[i].wait_cnt, bt->wake_cnt);
+ }
- bt_update_count(bt, depth);
return 0;
}
diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h
index 98696a65d4d4..6206ed17ef76 100644
--- a/block/blk-mq-tag.h
+++ b/block/blk-mq-tag.h
@@ -24,7 +24,7 @@ struct blk_mq_bitmap_tags {
unsigned int map_nr;
struct blk_align_bitmap *map;
- unsigned int wake_index;
+ atomic_t wake_index;
struct bt_wait_state *bs;
};
diff --git a/block/blk-mq.c b/block/blk-mq.c
index e11f5f8e0313..0ef2dc7f01bf 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -109,7 +109,7 @@ static void blk_mq_queue_exit(struct request_queue *q)
__percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
}
-static void __blk_mq_drain_queue(struct request_queue *q)
+void blk_mq_drain_queue(struct request_queue *q)
{
while (true) {
s64 count;
@@ -120,7 +120,7 @@ static void __blk_mq_drain_queue(struct request_queue *q)
if (count == 0)
break;
- blk_mq_run_queues(q, false);
+ blk_mq_start_hw_queues(q);
msleep(10);
}
}
@@ -139,12 +139,7 @@ static void blk_mq_freeze_queue(struct request_queue *q)
spin_unlock_irq(q->queue_lock);
if (drain)
- __blk_mq_drain_queue(q);
-}
-
-void blk_mq_drain_queue(struct request_queue *q)
-{
- __blk_mq_drain_queue(q);
+ blk_mq_drain_queue(q);
}
static void blk_mq_unfreeze_queue(struct request_queue *q)
diff --git a/block/blk.h b/block/blk.h
index 45385e9abf6f..6748c4f8d7a1 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -84,7 +84,6 @@ static inline void blk_clear_rq_complete(struct request *rq)
#define ELV_ON_HASH(rq) ((rq)->cmd_flags & REQ_HASHED)
void blk_insert_flush(struct request *rq);
-void blk_abort_flushes(struct request_queue *q);
static inline struct request *__elv_next_request(struct request_queue *q)
{
diff --git a/block/elevator.c b/block/elevator.c
index f35edddfe9b5..34bded18910e 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -729,26 +729,6 @@ int elv_may_queue(struct request_queue *q, int rw)
return ELV_MQUEUE_MAY;
}
-void elv_abort_queue(struct request_queue *q)
-{
- struct request *rq;
-
- blk_abort_flushes(q);
-
- while (!list_empty(&q->queue_head)) {
- rq = list_entry_rq(q->queue_head.next);
- rq->cmd_flags |= REQ_QUIET;
- trace_block_rq_abort(q, rq);
- /*
- * Mark this request as started so we don't trigger
- * any debug logic in the end I/O path.
- */
- blk_start_request(rq);
- __blk_end_request_all(rq, -EIO);
- }
-}
-EXPORT_SYMBOL(elv_abort_queue);
-
void elv_completed_request(struct request_queue *q, struct request *rq)
{
struct elevator_queue *e = q->elevator;