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Message-ID: <20170113083051.GD637@infradead.org>
Date: Fri, 13 Jan 2017 00:30:51 -0800
From: Christoph Hellwig <hch@...radead.org>
To: Jens Axboe <axboe@...com>
Cc: linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
osandov@...ndov.com, bart.vanassche@...disk.com
Subject: Re: [PATCH 06/10] blk-mq-tag: cleanup the normal/reserved tag
allocation
On Wed, Jan 11, 2017 at 02:39:59PM -0700, Jens Axboe wrote:
> This is in preparation for having another tag set available. Cleanup
> the parameters, and allow passing in of tags fo blk_mq_put_tag().
I've been playing around with this are a bit but never submitted
anything. Below is an untested merge of my previous bits with your
patch, let me know what you think about it:
---
>From c9ea92bfb468e9116149db95d246e48ace2b87f1 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@...com>
Date: Wed, 11 Jan 2017 11:04:53 -0700
Subject: blk-mq-tag: cleanup the normal/reserved tag allocation
This is in preparation for having another tag set available. Cleanup
the parameters, and allow passing in of tags for blk_mq_put_tag().
Signed-off-by: Jens Axboe <axboe@...com>
[hch: even more cleanups]
Signed-off-by: Christoph Hellwig <hch@....de>
---
block/blk-mq-tag.c | 94 +++++++++++++++++++++---------------------------------
block/blk-mq-tag.h | 4 +--
block/blk-mq.c | 2 +-
block/blk-mq.h | 5 +++
4 files changed, 44 insertions(+), 61 deletions(-)
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index dcf5ce3..ced7527 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -90,32 +90,46 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
return atomic_read(&hctx->nr_active) < depth;
}
-static int __bt_get(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt)
+static int __blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt)
{
if (!hctx_may_queue(hctx, bt))
return -1;
return __sbitmap_queue_get(bt);
}
-static int bt_get(struct blk_mq_alloc_data *data, struct sbitmap_queue *bt,
- struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags)
+unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
{
+ struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
+ struct sbitmap_queue *bt;
struct sbq_wait_state *ws;
DEFINE_WAIT(wait);
+ unsigned int tag_offset;
int tag;
- tag = __bt_get(hctx, bt);
+ if (data->flags & BLK_MQ_REQ_RESERVED) {
+ if (unlikely(!tags->nr_reserved_tags)) {
+ WARN_ON_ONCE(1);
+ return BLK_MQ_TAG_FAIL;
+ }
+ bt = &tags->breserved_tags;
+ tag_offset = 0;
+ } else {
+ bt = &tags->bitmap_tags;
+ tag_offset = tags->nr_reserved_tags;
+ }
+
+ tag = __blk_mq_get_tag(data->hctx, bt);
if (tag != -1)
- return tag;
+ goto found_tag;
if (data->flags & BLK_MQ_REQ_NOWAIT)
- return -1;
+ return BLK_MQ_TAG_FAIL;
- ws = bt_wait_ptr(bt, hctx);
+ ws = bt_wait_ptr(bt, data->hctx);
do {
prepare_to_wait(&ws->wait, &wait, TASK_UNINTERRUPTIBLE);
- tag = __bt_get(hctx, bt);
+ tag = __blk_mq_get_tag(data->hctx, bt);
if (tag != -1)
break;
@@ -125,14 +139,14 @@ static int bt_get(struct blk_mq_alloc_data *data, struct sbitmap_queue *bt,
* some to complete. Note that hctx can be NULL here for
* reserved tag allocation.
*/
- if (hctx)
- blk_mq_run_hw_queue(hctx, false);
+ if (data->hctx)
+ blk_mq_run_hw_queue(data->hctx, false);
/*
* Retry tag allocation after running the hardware queue,
* as running the queue may also have found completions.
*/
- tag = __bt_get(hctx, bt);
+ tag = __blk_mq_get_tag(data->hctx, bt);
if (tag != -1)
break;
@@ -142,61 +156,25 @@ static int bt_get(struct blk_mq_alloc_data *data, struct sbitmap_queue *bt,
data->ctx = blk_mq_get_ctx(data->q);
data->hctx = blk_mq_map_queue(data->q, data->ctx->cpu);
- if (data->flags & BLK_MQ_REQ_RESERVED) {
- bt = &data->hctx->tags->breserved_tags;
- } else {
- hctx = data->hctx;
- bt = &hctx->tags->bitmap_tags;
- }
+ tags = blk_mq_tags_from_data(data);
+ if (data->flags & BLK_MQ_REQ_RESERVED)
+ bt = &tags->breserved_tags;
+ else
+ bt = &tags->bitmap_tags;
+
finish_wait(&ws->wait, &wait);
- ws = bt_wait_ptr(bt, hctx);
+ ws = bt_wait_ptr(bt, data->hctx);
} while (1);
finish_wait(&ws->wait, &wait);
- return tag;
-}
-
-static unsigned int __blk_mq_get_tag(struct blk_mq_alloc_data *data)
-{
- int tag;
-
- tag = bt_get(data, &data->hctx->tags->bitmap_tags, data->hctx,
- data->hctx->tags);
- if (tag >= 0)
- return tag + data->hctx->tags->nr_reserved_tags;
-
- return BLK_MQ_TAG_FAIL;
-}
-
-static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_alloc_data *data)
-{
- int tag;
- if (unlikely(!data->hctx->tags->nr_reserved_tags)) {
- WARN_ON_ONCE(1);
- return BLK_MQ_TAG_FAIL;
- }
-
- tag = bt_get(data, &data->hctx->tags->breserved_tags, NULL,
- data->hctx->tags);
- if (tag < 0)
- return BLK_MQ_TAG_FAIL;
-
- return tag;
+found_tag:
+ return tag + tag_offset;
}
-unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
+void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags,
+ struct blk_mq_ctx *ctx, unsigned int tag)
{
- if (data->flags & BLK_MQ_REQ_RESERVED)
- return __blk_mq_get_reserved_tag(data);
- return __blk_mq_get_tag(data);
-}
-
-void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
- unsigned int tag)
-{
- struct blk_mq_tags *tags = hctx->tags;
-
if (tag >= tags->nr_reserved_tags) {
const int real_tag = tag - tags->nr_reserved_tags;
diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h
index d166273..923602d 100644
--- a/block/blk-mq-tag.h
+++ b/block/blk-mq-tag.h
@@ -24,8 +24,8 @@ extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, unsigned int r
extern void blk_mq_free_tags(struct blk_mq_tags *tags);
extern unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data);
-extern void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
- unsigned int tag);
+extern void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags,
+ struct blk_mq_ctx *ctx, unsigned int tag);
extern bool blk_mq_has_free_tags(struct blk_mq_tags *tags);
extern ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page);
extern int blk_mq_tag_update_depth(struct blk_mq_tags *tags, unsigned int depth);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 9fc5217..6fab8e9 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -335,7 +335,7 @@ void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
- blk_mq_put_tag(hctx, ctx, tag);
+ blk_mq_put_tag(hctx, hctx->tags, ctx, tag);
blk_queue_exit(q);
}
diff --git a/block/blk-mq.h b/block/blk-mq.h
index e59f5ca..48b7771 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -118,6 +118,11 @@ static inline void blk_mq_set_alloc_data(struct blk_mq_alloc_data *data,
data->hctx = hctx;
}
+static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data *data)
+{
+ return data->hctx->tags;
+}
+
/*
* Internal helpers for request allocation/init/free
*/
--
2.1.4
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