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Date: Mon, 4 Jun 2012 10:41:50 -0400
From: Tao Guo <glorioustao@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Tao Guo <glorioustao@...il.com>, Tao Guo <Tao.Guo@....com>,
Neil Brown <neilb@...e.de>, Jens Axboe <axboe@...nel.dk>,
<stable@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 1/2] block: Move general unplug callback function from md/raid to blk-core
Other components may also require an unplug callback, so move this
function from md/raid to block generic layer.
Signed-off-by: Tao Guo <Tao.Guo@....com>
Cc: Neil Brown <neilb@...e.de>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: <stable@...r.kernel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: <stable@...r.kernel.org>
---
block/blk-core.c | 36 ++++++++++++++++++++++++++++++++-
block/blk-settings.c | 1 +
block/blk.h | 1 -
drivers/md/md.c | 51 ++++-------------------------------------------
drivers/md/md.h | 3 --
drivers/md/raid1.c | 2 +-
drivers/md/raid5.c | 4 +-
include/linux/blkdev.h | 8 ++++++-
8 files changed, 51 insertions(+), 55 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 3c923a7..5639a3d 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2840,6 +2840,39 @@ void blk_start_plug(struct blk_plug *plug)
}
EXPORT_SYMBOL(blk_start_plug);
+/* Check that an unplug wakeup will come shortly.
+ */
+bool blk_check_plugged(struct request_queue *q, plug_cb_fn cb_fn)
+{
+ struct blk_plug *plug = current->plug;
+ struct blk_plug_cb *cb;
+
+ if (!plug)
+ return false;
+
+ list_for_each_entry(cb, &plug->cb_list, list) {
+ if (cb->cb_fn == cb_fn && cb->q == q) {
+ /* Already on the list, move to top */
+ if (cb != list_first_entry(&plug->cb_list,
+ struct blk_plug_cb,
+ list))
+ list_move(&cb->list, &plug->cb_list);
+ return true;
+ }
+ }
+ /* Not currently on the callback list */
+ cb = kmalloc(sizeof(*cb), GFP_ATOMIC);
+ if (!cb)
+ return false;
+
+ cb->q = q;
+ cb->cb_fn = cb_fn;
+ atomic_inc(&q->plug_cnt);
+ list_add(&cb->list, &plug->cb_list);
+ return true;
+}
+EXPORT_SYMBOL(blk_check_plugged);
+
static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
{
struct request *rqa = container_of(a, struct request, queuelist);
@@ -2897,7 +2930,8 @@ static void flush_plug_callbacks(struct blk_plug *plug)
struct blk_plug_cb,
list);
list_del(&cb->list);
- cb->callback(cb);
+ cb->cb_fn(cb);
+ kfree(cb);
}
}
diff --git a/block/blk-settings.c b/block/blk-settings.c
index d3234fc..c54d603 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -181,6 +181,7 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
blk_queue_dma_alignment(q, 511);
blk_queue_congestion_threshold(q);
q->nr_batching = BLK_BATCH_REQ;
+ atomic_set(&q->plug_cnt, 0);
blk_set_default_limits(&q->limits);
diff --git a/block/blk.h b/block/blk.h
index 85f6ae4..a62195b 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -33,7 +33,6 @@ bool __blk_end_bidi_request(struct request *rq, int error,
void blk_rq_timed_out_timer(unsigned long data);
void blk_delete_timer(struct request *);
void blk_add_timer(struct request *);
-void __generic_unplug_device(struct request_queue *);
/*
* Internal atomic flags for request handling
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1c2f904..08b64ef 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -498,25 +498,11 @@ void md_flush_request(struct mddev *mddev, struct bio *bio)
}
EXPORT_SYMBOL(md_flush_request);
-/* Support for plugging.
- * This mirrors the plugging support in request_queue, but does not
- * require having a whole queue or request structures.
- * We allocate an md_plug_cb for each md device and each thread it gets
- * plugged on. This links tot the private plug_handle structure in the
- * personality data where we keep a count of the number of outstanding
- * plugs so other code can see if a plug is active.
- */
-struct md_plug_cb {
- struct blk_plug_cb cb;
- struct mddev *mddev;
-};
-
-static void plugger_unplug(struct blk_plug_cb *cb)
+static void mddev_unplug(struct blk_plug_cb *cb)
{
- struct md_plug_cb *mdcb = container_of(cb, struct md_plug_cb, cb);
- if (atomic_dec_and_test(&mdcb->mddev->plug_cnt))
- md_wakeup_thread(mdcb->mddev->thread);
- kfree(mdcb);
+ struct mddev *mddev = cb->q->queuedata;
+ if (atomic_dec_and_test(&cb->q->plug_cnt))
+ md_wakeup_thread(mddev->thread);
}
/* Check that an unplug wakeup will come shortly.
@@ -524,33 +510,7 @@ static void plugger_unplug(struct blk_plug_cb *cb)
*/
int mddev_check_plugged(struct mddev *mddev)
{
- struct blk_plug *plug = current->plug;
- struct md_plug_cb *mdcb;
-
- if (!plug)
- return 0;
-
- list_for_each_entry(mdcb, &plug->cb_list, cb.list) {
- if (mdcb->cb.callback == plugger_unplug &&
- mdcb->mddev == mddev) {
- /* Already on the list, move to top */
- if (mdcb != list_first_entry(&plug->cb_list,
- struct md_plug_cb,
- cb.list))
- list_move(&mdcb->cb.list, &plug->cb_list);
- return 1;
- }
- }
- /* Not currently on the callback list */
- mdcb = kmalloc(sizeof(*mdcb), GFP_ATOMIC);
- if (!mdcb)
- return 0;
-
- mdcb->mddev = mddev;
- mdcb->cb.callback = plugger_unplug;
- atomic_inc(&mddev->plug_cnt);
- list_add(&mdcb->cb.list, &plug->cb_list);
- return 1;
+ return blk_check_plugged(mddev->queue, mddev_unplug);
}
EXPORT_SYMBOL_GPL(mddev_check_plugged);
@@ -602,7 +562,6 @@ void mddev_init(struct mddev *mddev)
atomic_set(&mddev->active, 1);
atomic_set(&mddev->openers, 0);
atomic_set(&mddev->active_io, 0);
- atomic_set(&mddev->plug_cnt, 0);
spin_lock_init(&mddev->write_lock);
atomic_set(&mddev->flush_pending, 0);
init_waitqueue_head(&mddev->sb_wait);
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 7b4a3c3..91786c4 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -266,9 +266,6 @@ struct mddev {
int new_chunk_sectors;
int reshape_backwards;
- atomic_t plug_cnt; /* If device is expecting
- * more bios soon.
- */
struct md_thread *thread; /* management thread */
struct md_thread *sync_thread; /* doing resync or reconstruct */
sector_t curr_resync; /* last block scheduled */
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 835de71..6e6d65f 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2170,7 +2170,7 @@ static void raid1d(struct mddev *mddev)
blk_start_plug(&plug);
for (;;) {
- if (atomic_read(&mddev->plug_cnt) == 0)
+ if (atomic_read(&mddev->queue->plug_cnt) == 0)
flush_pending_writes(conf);
spin_lock_irqsave(&conf->device_lock, flags);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index d267672..e98bf00 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4521,7 +4521,7 @@ static void raid5d(struct mddev *mddev)
while (1) {
struct bio *bio;
- if (atomic_read(&mddev->plug_cnt) == 0 &&
+ if (atomic_read(&mddev->queue->plug_cnt) == 0 &&
!list_empty(&conf->bitmap_list)) {
/* Now is a good time to flush some bitmap updates */
conf->seq_flush++;
@@ -4531,7 +4531,7 @@ static void raid5d(struct mddev *mddev)
conf->seq_write = conf->seq_flush;
activate_bit_delay(conf);
}
- if (atomic_read(&mddev->plug_cnt) == 0)
+ if (atomic_read(&mddev->queue->plug_cnt) == 0)
raid5_activate_delayed(conf);
while ((bio = remove_bio_from_retry(conf))) {
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ba43f40..69945e4 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -316,6 +316,9 @@ struct request_queue {
* ll_rw_blk doesn't touch it.
*/
void *queuedata;
+ atomic_t plug_cnt; /* If device is expecting
+ * more bios soon.
+ */
/*
* various queue flags, see QUEUE_* below
@@ -914,12 +917,15 @@ struct blk_plug {
struct blk_plug_cb {
struct list_head list;
- void (*callback)(struct blk_plug_cb *);
+ struct request_queue *q;
+ void (*cb_fn)(struct blk_plug_cb *);
};
+typedef void (plug_cb_fn) (struct blk_plug_cb *cb);
extern void blk_start_plug(struct blk_plug *);
extern void blk_finish_plug(struct blk_plug *);
extern void blk_flush_plug_list(struct blk_plug *, bool);
+extern bool blk_check_plugged(struct request_queue *q, plug_cb_fn cb_fn);
static inline void blk_flush_plug(struct task_struct *tsk)
{
--
1.7.7.6
--
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