block: introduce blk_flush_queue to drive flush machinery

This patch introduces 'struct blk_flush_queue' and puts all
flush machinery related fields into this structure, so that

	- flush implementation details aren't exposed to driver
	- it is easy to convert to per dispatch-queue flush machinery

This patch is basically a mechanical replacement.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-core.c b/block/blk-core.c
index 222fe84..cfaca8c 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -390,11 +390,13 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all)
                 * be drained.  Check all the queues and counters.
                 */
                if (drain_all) {
+                       struct blk_flush_queue *fq = blk_get_flush_queue(q);
                        drain |= !list_empty(&q->queue_head);
                        for (i = 0; i < 2; i++) {
                                drain |= q->nr_rqs[i];
                                drain |= q->in_flight[i];
-                               drain |= !list_empty(&q->flush_queue[i]);
+                               if (fq)
+                                   drain |= !list_empty(&fq->flush_queue[i]);
                        }
                }
 

diff --git a/block/blk-flush.c b/block/blk-flush.c
index caf4475..b01a86d 100644 (file)
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -28,7 +28,7 @@
  *
  * The actual execution of flush is double buffered.  Whenever a request
  * needs to execute PRE or POSTFLUSH, it queues at
- * q->flush_queue[q->flush_pending_idx].  Once certain criteria are met, a
+ * fq->flush_queue[fq->flush_pending_idx].  Once certain criteria are met, a
  * flush is issued and the pending_idx is toggled.  When the flush
  * completes, all the requests which were pending are proceeded to the next
  * step.  This allows arbitrary merging of different types of FLUSH/FUA
@@ -155,7 +155,7 @@ static bool blk_flush_queue_rq(struct request *rq, bool add_front)
  * completion and trigger the next step.
  *
  * CONTEXT:
- * spin_lock_irq(q->queue_lock or q->mq_flush_lock)
+ * spin_lock_irq(q->queue_lock or fq->mq_flush_lock)
  *
  * RETURNS:
  * %true if requests were added to the dispatch queue, %false otherwise.
@@ -164,7 +164,8 @@ static bool blk_flush_complete_seq(struct request *rq, unsigned int seq,
                                   int error)
 {
        struct request_queue *q = rq->q;
-       struct list_head *pending = &q->flush_queue[q->flush_pending_idx];
+       struct blk_flush_queue *fq = blk_get_flush_queue(q);
+       struct list_head *pending = &fq->flush_queue[fq->flush_pending_idx];
        bool queued = false, kicked;
 
        BUG_ON(rq->flush.seq & seq);
@@ -180,12 +181,12 @@ static bool blk_flush_complete_seq(struct request *rq, unsigned int seq,
        case REQ_FSEQ_POSTFLUSH:
                /* queue for flush */
                if (list_empty(pending))
-                       q->flush_pending_since = jiffies;
+                       fq->flush_pending_since = jiffies;
                list_move_tail(&rq->flush.list, pending);
                break;
 
        case REQ_FSEQ_DATA:
-               list_move_tail(&rq->flush.list, &q->flush_data_in_flight);
+               list_move_tail(&rq->flush.list, &fq->flush_data_in_flight);
                queued = blk_flush_queue_rq(rq, true);
                break;
 
@@ -220,17 +221,18 @@ static void flush_end_io(struct request *flush_rq, int error)
        bool queued = false;
        struct request *rq, *n;
        unsigned long flags = 0;
+       struct blk_flush_queue *fq = blk_get_flush_queue(q);
 
        if (q->mq_ops) {
-               spin_lock_irqsave(&q->mq_flush_lock, flags);
+               spin_lock_irqsave(&fq->mq_flush_lock, flags);
                flush_rq->tag = -1;
        }
 
-       running = &q->flush_queue[q->flush_running_idx];
-       BUG_ON(q->flush_pending_idx == q->flush_running_idx);
+       running = &fq->flush_queue[fq->flush_running_idx];
+       BUG_ON(fq->flush_pending_idx == fq->flush_running_idx);
 
        /* account completion of the flush request */
-       q->flush_running_idx ^= 1;
+       fq->flush_running_idx ^= 1;
 
        if (!q->mq_ops)
                elv_completed_request(q, flush_rq);
@@ -254,13 +256,13 @@ static void flush_end_io(struct request *flush_rq, int error)
         * directly into request_fn may confuse the driver.  Always use
         * kblockd.
         */
-       if (queued || q->flush_queue_delayed) {
+       if (queued || fq->flush_queue_delayed) {
                WARN_ON(q->mq_ops);
                blk_run_queue_async(q);
        }
-       q->flush_queue_delayed = 0;
+       fq->flush_queue_delayed = 0;
        if (q->mq_ops)
-               spin_unlock_irqrestore(&q->mq_flush_lock, flags);
+               spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
 }
 
 /**
@@ -271,33 +273,34 @@ static void flush_end_io(struct request *flush_rq, int error)
  * Please read the comment at the top of this file for more info.
  *
  * CONTEXT:
- * spin_lock_irq(q->queue_lock or q->mq_flush_lock)
+ * spin_lock_irq(q->queue_lock or fq->mq_flush_lock)
  *
  * RETURNS:
  * %true if flush was issued, %false otherwise.
  */
 static bool blk_kick_flush(struct request_queue *q)
 {
-       struct list_head *pending = &q->flush_queue[q->flush_pending_idx];
+       struct blk_flush_queue *fq = blk_get_flush_queue(q);
+       struct list_head *pending = &fq->flush_queue[fq->flush_pending_idx];
        struct request *first_rq =
                list_first_entry(pending, struct request, flush.list);
-       struct request *flush_rq = q->flush_rq;
+       struct request *flush_rq = fq->flush_rq;
 
        /* C1 described at the top of this file */
-       if (q->flush_pending_idx != q->flush_running_idx || list_empty(pending))
+       if (fq->flush_pending_idx != fq->flush_running_idx || list_empty(pending))
                return false;
 
        /* C2 and C3 */
-       if (!list_empty(&q->flush_data_in_flight) &&
+       if (!list_empty(&fq->flush_data_in_flight) &&
            time_before(jiffies,
-                       q->flush_pending_since + FLUSH_PENDING_TIMEOUT))
+                       fq->flush_pending_since + FLUSH_PENDING_TIMEOUT))
                return false;
 
        /*
         * Issue flush and toggle pending_idx.  This makes pending_idx
         * different from running_idx, which means flush is in flight.
         */
-       q->flush_pending_idx ^= 1;
+       fq->flush_pending_idx ^= 1;
 
        blk_rq_init(q, flush_rq);
        if (q->mq_ops)
@@ -329,6 +332,7 @@ static void mq_flush_data_end_io(struct request *rq, int error)
        struct blk_mq_hw_ctx *hctx;
        struct blk_mq_ctx *ctx;
        unsigned long flags;
+       struct blk_flush_queue *fq = blk_get_flush_queue(q);
 
        ctx = rq->mq_ctx;
        hctx = q->mq_ops->map_queue(q, ctx->cpu);
@@ -337,10 +341,10 @@ static void mq_flush_data_end_io(struct request *rq, int error)
         * After populating an empty queue, kick it to avoid stall.  Read
         * the comment in flush_end_io().
         */
-       spin_lock_irqsave(&q->mq_flush_lock, flags);
+       spin_lock_irqsave(&fq->mq_flush_lock, flags);
        if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error))
                blk_mq_run_hw_queue(hctx, true);
-       spin_unlock_irqrestore(&q->mq_flush_lock, flags);
+       spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
 }
 
 /**
@@ -408,11 +412,13 @@ void blk_insert_flush(struct request *rq)
        rq->cmd_flags |= REQ_FLUSH_SEQ;
        rq->flush.saved_end_io = rq->end_io; /* Usually NULL */
        if (q->mq_ops) {
+               struct blk_flush_queue *fq = blk_get_flush_queue(q);
+
                rq->end_io = mq_flush_data_end_io;
 
-               spin_lock_irq(&q->mq_flush_lock);
+               spin_lock_irq(&fq->mq_flush_lock);
                blk_flush_complete_seq(rq, REQ_FSEQ_ACTIONS & ~policy, 0);
-               spin_unlock_irq(&q->mq_flush_lock);
+               spin_unlock_irq(&fq->mq_flush_lock);
                return;
        }
        rq->end_io = flush_data_end_io;
@@ -473,31 +479,52 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 }
 EXPORT_SYMBOL(blkdev_issue_flush);
 
-static int blk_mq_init_flush(struct request_queue *q)
+static struct blk_flush_queue *blk_alloc_flush_queue(
+               struct request_queue *q)
 {
-       struct blk_mq_tag_set *set = q->tag_set;
+       struct blk_flush_queue *fq;
+       int rq_sz = sizeof(struct request);
 
-       spin_lock_init(&q->mq_flush_lock);
+       fq = kzalloc(sizeof(*fq), GFP_KERNEL);
+       if (!fq)
+               goto fail;
 
-       q->flush_rq = kzalloc(round_up(sizeof(struct request) +
-                               set->cmd_size, cache_line_size()),
-                               GFP_KERNEL);
-       if (!q->flush_rq)
-               return -ENOMEM;
-       return 0;
+       if (q->mq_ops) {
+               spin_lock_init(&fq->mq_flush_lock);
+               rq_sz = round_up(rq_sz + q->tag_set->cmd_size,
+                               cache_line_size());
+       }
+
+       fq->flush_rq = kzalloc(rq_sz, GFP_KERNEL);
+       if (!fq->flush_rq)
+               goto fail_rq;
+
+       INIT_LIST_HEAD(&fq->flush_queue[0]);
+       INIT_LIST_HEAD(&fq->flush_queue[1]);
+       INIT_LIST_HEAD(&fq->flush_data_in_flight);
+
+       return fq;
+
+ fail_rq:
+       kfree(fq);
+ fail:
+       return NULL;
 }
 
-int blk_init_flush(struct request_queue *q)
+static void blk_free_flush_queue(struct blk_flush_queue *fq)
 {
-       INIT_LIST_HEAD(&q->flush_queue[0]);
-       INIT_LIST_HEAD(&q->flush_queue[1]);
-       INIT_LIST_HEAD(&q->flush_data_in_flight);
+       /* bio based request queue hasn't flush queue */
+       if (!fq)
+               return;
 
-       if (q->mq_ops)
-               return blk_mq_init_flush(q);
+       kfree(fq->flush_rq);
+       kfree(fq);
+}
 
-       q->flush_rq = kzalloc(sizeof(struct request), GFP_KERNEL);
-       if (!q->flush_rq)
+int blk_init_flush(struct request_queue *q)
+{
+       q->fq = blk_alloc_flush_queue(q);
+       if (!q->fq)
                return -ENOMEM;
 
        return 0;
@@ -505,5 +532,5 @@ int blk_init_flush(struct request_queue *q)
 
 void blk_exit_flush(struct request_queue *q)
 {
-       kfree(q->flush_rq);
+       blk_free_flush_queue(q->fq);
 }

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 2758cdf..d39e8a5 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -508,20 +508,22 @@ void blk_mq_kick_requeue_list(struct request_queue *q)
 }
 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
 
-static inline bool is_flush_request(struct request *rq, unsigned int tag)
+static inline bool is_flush_request(struct request *rq,
+               struct blk_flush_queue *fq, unsigned int tag)
 {
        return ((rq->cmd_flags & REQ_FLUSH_SEQ) &&
-                       rq->q->flush_rq->tag == tag);
+                       fq->flush_rq->tag == tag);
 }
 
 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
 {
        struct request *rq = tags->rqs[tag];
+       struct blk_flush_queue *fq = blk_get_flush_queue(rq->q);
 
-       if (!is_flush_request(rq, tag))
+       if (!is_flush_request(rq, fq, tag))
                return rq;
 
-       return rq->q->flush_rq;
+       return fq->flush_rq;
 }
 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 

diff --git a/block/blk.h b/block/blk.h
index c6fa3d4..833c4ac 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -12,11 +12,28 @@
 /* Max future timer expiry for timeouts */
 #define BLK_MAX_TIMEOUT                (5 * HZ)
 
+struct blk_flush_queue {
+       unsigned int            flush_queue_delayed:1;
+       unsigned int            flush_pending_idx:1;
+       unsigned int            flush_running_idx:1;
+       unsigned long           flush_pending_since;
+       struct list_head        flush_queue[2];
+       struct list_head        flush_data_in_flight;
+       struct request          *flush_rq;
+       spinlock_t              mq_flush_lock;
+};
+
 extern struct kmem_cache *blk_requestq_cachep;
 extern struct kmem_cache *request_cachep;
 extern struct kobj_type blk_queue_ktype;
 extern struct ida blk_queue_ida;
 
+static inline struct blk_flush_queue *blk_get_flush_queue(
+               struct request_queue *q)
+{
+       return q->fq;
+}
+
 static inline void __blk_get_queue(struct request_queue *q)
 {
        kobject_get(&q->kobj);
@@ -89,6 +106,7 @@ void blk_insert_flush(struct request *rq);
 static inline struct request *__elv_next_request(struct request_queue *q)
 {
        struct request *rq;
+       struct blk_flush_queue *fq = blk_get_flush_queue(q);
 
        while (1) {
                if (!list_empty(&q->queue_head)) {
@@ -111,9 +129,9 @@ static inline struct request *__elv_next_request(struct request_queue *q)
                 * should be restarted later. Please see flush_end_io() for
                 * details.
                 */
-               if (q->flush_pending_idx != q->flush_running_idx &&
+               if (fq->flush_pending_idx != fq->flush_running_idx &&
                                !queue_flush_queueable(q)) {
-                       q->flush_queue_delayed = 1;
+                       fq->flush_queue_delayed = 1;
                        return NULL;
                }
                if (unlikely(blk_queue_bypass(q)) ||

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e267bf0..49f3461 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -36,6 +36,7 @@ struct request;
 struct sg_io_hdr;
 struct bsg_job;
 struct blkcg_gq;
+struct blk_flush_queue;
 
 #define BLKDEV_MIN_RQ  4
 #define BLKDEV_MAX_RQ  128     /* Default maximum */
@@ -455,14 +456,7 @@ struct request_queue {
         */
        unsigned int            flush_flags;
        unsigned int            flush_not_queueable:1;
-       unsigned int            flush_queue_delayed:1;
-       unsigned int            flush_pending_idx:1;
-       unsigned int            flush_running_idx:1;
-       unsigned long           flush_pending_since;
-       struct list_head        flush_queue[2];
-       struct list_head        flush_data_in_flight;
-       struct request          *flush_rq;
-       spinlock_t              mq_flush_lock;
+       struct blk_flush_queue  *fq;
 
        struct list_head        requeue_list;
        spinlock_t              requeue_lock;