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-rw-r--r--block/blk-core.c281
1 files changed, 188 insertions, 93 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 1f61b74867e4..3c923a7aeb56 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -29,11 +29,13 @@
#include <linux/fault-inject.h>
#include <linux/list_sort.h>
#include <linux/delay.h>
+#include <linux/ratelimit.h>
#define CREATE_TRACE_POINTS
#include <trace/events/block.h>
#include "blk.h"
+#include "blk-cgroup.h"
EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
@@ -280,7 +282,7 @@ EXPORT_SYMBOL(blk_stop_queue);
*
* This function does not cancel any asynchronous activity arising
* out of elevator or throttling code. That would require elevaotor_exit()
- * and blk_throtl_exit() to be called with queue lock initialized.
+ * and blkcg_exit_queue() to be called with queue lock initialized.
*
*/
void blk_sync_queue(struct request_queue *q)
@@ -365,17 +367,23 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
spin_lock_irq(q->queue_lock);
- elv_drain_elevator(q);
- if (drain_all)
- blk_throtl_drain(q);
+ /*
+ * The caller might be trying to drain @q before its
+ * elevator is initialized.
+ */
+ if (q->elevator)
+ elv_drain_elevator(q);
+
+ blkcg_drain_queue(q);
/*
* This function might be called on a queue which failed
- * driver init after queue creation. Some drivers
- * (e.g. fd) get unhappy in such cases. Kick queue iff
- * dispatch queue has something on it.
+ * driver init after queue creation or is not yet fully
+ * active yet. Some drivers (e.g. fd and loop) get unhappy
+ * in such cases. Kick queue iff dispatch queue has
+ * something on it and @q has request_fn set.
*/
- if (!list_empty(&q->queue_head))
+ if (!list_empty(&q->queue_head) && q->request_fn)
__blk_run_queue(q);
drain |= q->rq.elvpriv;
@@ -403,6 +411,49 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
}
/**
+ * blk_queue_bypass_start - enter queue bypass mode
+ * @q: queue of interest
+ *
+ * In bypass mode, only the dispatch FIFO queue of @q is used. This
+ * function makes @q enter bypass mode and drains all requests which were
+ * throttled or issued before. On return, it's guaranteed that no request
+ * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
+ * inside queue or RCU read lock.
+ */
+void blk_queue_bypass_start(struct request_queue *q)
+{
+ bool drain;
+
+ spin_lock_irq(q->queue_lock);
+ drain = !q->bypass_depth++;
+ queue_flag_set(QUEUE_FLAG_BYPASS, q);
+ spin_unlock_irq(q->queue_lock);
+
+ if (drain) {
+ blk_drain_queue(q, false);
+ /* ensure blk_queue_bypass() is %true inside RCU read lock */
+ synchronize_rcu();
+ }
+}
+EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
+
+/**
+ * blk_queue_bypass_end - leave queue bypass mode
+ * @q: queue of interest
+ *
+ * Leave bypass mode and restore the normal queueing behavior.
+ */
+void blk_queue_bypass_end(struct request_queue *q)
+{
+ spin_lock_irq(q->queue_lock);
+ if (!--q->bypass_depth)
+ queue_flag_clear(QUEUE_FLAG_BYPASS, q);
+ WARN_ON_ONCE(q->bypass_depth < 0);
+ spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
+
+/**
* blk_cleanup_queue - shutdown a request queue
* @q: request queue to shutdown
*
@@ -418,6 +469,19 @@ void blk_cleanup_queue(struct request_queue *q)
queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
spin_lock_irq(lock);
+
+ /*
+ * Dead queue is permanently in bypass mode till released. Note
+ * that, unlike blk_queue_bypass_start(), we aren't performing
+ * synchronize_rcu() after entering bypass mode to avoid the delay
+ * as some drivers create and destroy a lot of queues while
+ * probing. This is still safe because blk_release_queue() will be
+ * called only after the queue refcnt drops to zero and nothing,
+ * RCU or not, would be traversing the queue by then.
+ */
+ q->bypass_depth++;
+ queue_flag_set(QUEUE_FLAG_BYPASS, q);
+
queue_flag_set(QUEUE_FLAG_NOMERGES, q);
queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
queue_flag_set(QUEUE_FLAG_DEAD, q);
@@ -428,13 +492,8 @@ void blk_cleanup_queue(struct request_queue *q)
spin_unlock_irq(lock);
mutex_unlock(&q->sysfs_lock);
- /*
- * Drain all requests queued before DEAD marking. The caller might
- * be trying to tear down @q before its elevator is initialized, in
- * which case we don't want to call into draining.
- */
- if (q->elevator)
- blk_drain_queue(q, true);
+ /* drain all requests queued before DEAD marking */
+ blk_drain_queue(q, true);
/* @q won't process any more request, flush async actions */
del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
@@ -498,14 +557,15 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
if (err)
goto fail_id;
- if (blk_throtl_init(q))
- goto fail_id;
-
setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
laptop_mode_timer_fn, (unsigned long) q);
setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
+ INIT_LIST_HEAD(&q->queue_head);
INIT_LIST_HEAD(&q->timeout_list);
INIT_LIST_HEAD(&q->icq_list);
+#ifdef CONFIG_BLK_CGROUP
+ INIT_LIST_HEAD(&q->blkg_list);
+#endif
INIT_LIST_HEAD(&q->flush_queue[0]);
INIT_LIST_HEAD(&q->flush_queue[1]);
INIT_LIST_HEAD(&q->flush_data_in_flight);
@@ -522,6 +582,18 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
*/
q->queue_lock = &q->__queue_lock;
+ /*
+ * A queue starts its life with bypass turned on to avoid
+ * unnecessary bypass on/off overhead and nasty surprises during
+ * init. The initial bypass will be finished at the end of
+ * blk_init_allocated_queue().
+ */
+ q->bypass_depth = 1;
+ __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
+
+ if (blkcg_init_queue(q))
+ goto fail_id;
+
return q;
fail_id:
@@ -614,15 +686,15 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
q->sg_reserved_size = INT_MAX;
- /*
- * all done
- */
- if (!elevator_init(q, NULL)) {
- blk_queue_congestion_threshold(q);
- return q;
- }
+ /* init elevator */
+ if (elevator_init(q, NULL))
+ return NULL;
- return NULL;
+ blk_queue_congestion_threshold(q);
+
+ /* all done, end the initial bypass */
+ blk_queue_bypass_end(q);
+ return q;
}
EXPORT_SYMBOL(blk_init_allocated_queue);
@@ -648,33 +720,6 @@ static inline void blk_free_request(struct request_queue *q, struct request *rq)
mempool_free(rq, q->rq.rq_pool);
}
-static struct request *
-blk_alloc_request(struct request_queue *q, struct io_cq *icq,
- unsigned int flags, gfp_t gfp_mask)
-{
- struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
-
- if (!rq)
- return NULL;
-
- blk_rq_init(q, rq);
-
- rq->cmd_flags = flags | REQ_ALLOCED;
-
- if (flags & REQ_ELVPRIV) {
- rq->elv.icq = icq;
- if (unlikely(elv_set_request(q, rq, gfp_mask))) {
- mempool_free(rq, q->rq.rq_pool);
- return NULL;
- }
- /* @rq->elv.icq holds on to io_context until @rq is freed */
- if (icq)
- get_io_context(icq->ioc);
- }
-
- return rq;
-}
-
/*
* ioc_batching returns true if the ioc is a valid batching request and
* should be given priority access to a request.
@@ -763,6 +808,22 @@ static bool blk_rq_should_init_elevator(struct bio *bio)
}
/**
+ * rq_ioc - determine io_context for request allocation
+ * @bio: request being allocated is for this bio (can be %NULL)
+ *
+ * Determine io_context to use for request allocation for @bio. May return
+ * %NULL if %current->io_context doesn't exist.
+ */
+static struct io_context *rq_ioc(struct bio *bio)
+{
+#ifdef CONFIG_BLK_CGROUP
+ if (bio && bio->bi_ioc)
+ return bio->bi_ioc;
+#endif
+ return current->io_context;
+}
+
+/**
* get_request - get a free request
* @q: request_queue to allocate request from
* @rw_flags: RW and SYNC flags
@@ -779,7 +840,7 @@ static bool blk_rq_should_init_elevator(struct bio *bio)
static struct request *get_request(struct request_queue *q, int rw_flags,
struct bio *bio, gfp_t gfp_mask)
{
- struct request *rq = NULL;
+ struct request *rq;
struct request_list *rl = &q->rq;
struct elevator_type *et;
struct io_context *ioc;
@@ -789,7 +850,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
int may_queue;
retry:
et = q->elevator->type;
- ioc = current->io_context;
+ ioc = rq_ioc(bio);
if (unlikely(blk_queue_dead(q)))
return NULL;
@@ -808,7 +869,7 @@ retry:
*/
if (!ioc && !retried) {
spin_unlock_irq(q->queue_lock);
- create_io_context(current, gfp_mask, q->node);
+ create_io_context(gfp_mask, q->node);
spin_lock_irq(q->queue_lock);
retried = true;
goto retry;
@@ -831,7 +892,7 @@ retry:
* process is not a "batcher", and not
* exempted by the IO scheduler
*/
- goto out;
+ return NULL;
}
}
}
@@ -844,7 +905,7 @@ retry:
* allocated with any setting of ->nr_requests
*/
if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
- goto out;
+ return NULL;
rl->count[is_sync]++;
rl->starved[is_sync] = 0;
@@ -859,8 +920,7 @@ retry:
* Also, lookup icq while holding queue_lock. If it doesn't exist,
* it will be created after releasing queue_lock.
*/
- if (blk_rq_should_init_elevator(bio) &&
- !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags)) {
+ if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
rw_flags |= REQ_ELVPRIV;
rl->elvpriv++;
if (et->icq_cache && ioc)
@@ -871,41 +931,36 @@ retry:
rw_flags |= REQ_IO_STAT;
spin_unlock_irq(q->queue_lock);
- /* create icq if missing */
- if ((rw_flags & REQ_ELVPRIV) && unlikely(et->icq_cache && !icq)) {
- icq = ioc_create_icq(q, gfp_mask);
- if (!icq)
- goto fail_icq;
- }
-
- rq = blk_alloc_request(q, icq, rw_flags, gfp_mask);
+ /* allocate and init request */
+ rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
+ if (!rq)
+ goto fail_alloc;
-fail_icq:
- if (unlikely(!rq)) {
- /*
- * Allocation failed presumably due to memory. Undo anything
- * we might have messed up.
- *
- * Allocating task should really be put onto the front of the
- * wait queue, but this is pretty rare.
- */
- spin_lock_irq(q->queue_lock);
- freed_request(q, rw_flags);
+ blk_rq_init(q, rq);
+ rq->cmd_flags = rw_flags | REQ_ALLOCED;
+
+ /* init elvpriv */
+ if (rw_flags & REQ_ELVPRIV) {
+ if (unlikely(et->icq_cache && !icq)) {
+ create_io_context(gfp_mask, q->node);
+ ioc = rq_ioc(bio);
+ if (!ioc)
+ goto fail_elvpriv;
+
+ icq = ioc_create_icq(ioc, q, gfp_mask);
+ if (!icq)
+ goto fail_elvpriv;
+ }
- /*
- * in the very unlikely event that allocation failed and no
- * requests for this direction was pending, mark us starved
- * so that freeing of a request in the other direction will
- * notice us. another possible fix would be to split the
- * rq mempool into READ and WRITE
- */
-rq_starved:
- if (unlikely(rl->count[is_sync] == 0))
- rl->starved[is_sync] = 1;
+ rq->elv.icq = icq;
+ if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
+ goto fail_elvpriv;
- goto out;
+ /* @rq->elv.icq holds io_context until @rq is freed */
+ if (icq)
+ get_io_context(icq->ioc);
}
-
+out:
/*
* ioc may be NULL here, and ioc_batching will be false. That's
* OK, if the queue is under the request limit then requests need
@@ -916,8 +971,48 @@ rq_starved:
ioc->nr_batch_requests--;
trace_block_getrq(q, bio, rw_flags & 1);
-out:
return rq;
+
+fail_elvpriv:
+ /*
+ * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
+ * and may fail indefinitely under memory pressure and thus
+ * shouldn't stall IO. Treat this request as !elvpriv. This will
+ * disturb iosched and blkcg but weird is bettern than dead.
+ */
+ printk_ratelimited(KERN_WARNING "%s: request aux data allocation failed, iosched may be disturbed\n",
+ dev_name(q->backing_dev_info.dev));
+
+ rq->cmd_flags &= ~REQ_ELVPRIV;
+ rq->elv.icq = NULL;
+
+ spin_lock_irq(q->queue_lock);
+ rl->elvpriv--;
+ spin_unlock_irq(q->queue_lock);
+ goto out;
+
+fail_alloc:
+ /*
+ * Allocation failed presumably due to memory. Undo anything we
+ * might have messed up.
+ *
+ * Allocating task should really be put onto the front of the wait
+ * queue, but this is pretty rare.
+ */
+ spin_lock_irq(q->queue_lock);
+ freed_request(q, rw_flags);
+
+ /*
+ * in the very unlikely event that allocation failed and no
+ * requests for this direction was pending, mark us starved so that
+ * freeing of a request in the other direction will notice
+ * us. another possible fix would be to split the rq mempool into
+ * READ and WRITE
+ */
+rq_starved:
+ if (unlikely(rl->count[is_sync] == 0))
+ rl->starved[is_sync] = 1;
+ return NULL;
}
/**
@@ -961,7 +1056,7 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
* up to a big batch of them for a small period time.
* See ioc_batching, ioc_set_batching
*/
- create_io_context(current, GFP_NOIO, q->node);
+ create_io_context(GFP_NOIO, q->node);
ioc_set_batching(q, current->io_context);
spin_lock_irq(q->queue_lock);