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Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  block: only force kblockd unplugging from the schedule() path
  block: cleanup the block plug helper functions
  block, blk-sysfs: Use the variable directly instead of a function call
  block: move queue run on unplug to kblockd
  block: kill queue_sync_plugs()
  block: readd plug trace event
  block: add callback function for unplug notification
  block: add comment on why we save and disable interrupts in flush_plug_list()
  block: fixup block IO unplug trace call
  block: remove block_unplug_timer() trace point
  block: splice plug list to local context
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@torvalds
torvalds committed Apr 15, 2011
2 parents a970f5d + f660378 commit 5853b4f
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Showing 6 changed files with 78 additions and 84 deletions.
86 changes: 46 additions & 40 deletions block/blk-core.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -198,19 +198,6 @@ void blk_dump_rq_flags(struct request *rq, char *msg)
}
EXPORT_SYMBOL(blk_dump_rq_flags);

/*
* Make sure that plugs that were pending when this function was entered,
* are now complete and requests pushed to the queue.
*/
static inline void queue_sync_plugs(struct request_queue *q)
{
/*
* If the current process is plugged and has barriers submitted,
* we will livelock if we don't unplug first.
*/
blk_flush_plug(current);
}

static void blk_delay_work(struct work_struct *work)
{
struct request_queue *q;
Expand Down Expand Up @@ -298,7 +285,6 @@ void blk_sync_queue(struct request_queue *q)
{
del_timer_sync(&q->timeout);
cancel_delayed_work_sync(&q->delay_work);
queue_sync_plugs(q);
}
EXPORT_SYMBOL(blk_sync_queue);

Expand Down Expand Up @@ -1311,7 +1297,15 @@ static int __make_request(struct request_queue *q, struct bio *bio)

plug = current->plug;
if (plug) {
if (!plug->should_sort && !list_empty(&plug->list)) {
/*
* If this is the first request added after a plug, fire
* of a plug trace. If others have been added before, check
* if we have multiple devices in this plug. If so, make a
* note to sort the list before dispatch.
*/
if (list_empty(&plug->list))
trace_block_plug(q);
else if (!plug->should_sort) {
struct request *__rq;

__rq = list_entry_rq(plug->list.prev);
Expand Down Expand Up @@ -2668,33 +2662,56 @@ static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
return !(rqa->q <= rqb->q);
}

static void flush_plug_list(struct blk_plug *plug)
static void queue_unplugged(struct request_queue *q, unsigned int depth,
bool force_kblockd)
{
trace_block_unplug_io(q, depth);
__blk_run_queue(q, force_kblockd);

if (q->unplugged_fn)
q->unplugged_fn(q);
}

void blk_flush_plug_list(struct blk_plug *plug, bool force_kblockd)
{
struct request_queue *q;
unsigned long flags;
struct request *rq;
LIST_HEAD(list);
unsigned int depth;

BUG_ON(plug->magic != PLUG_MAGIC);

if (list_empty(&plug->list))
return;

if (plug->should_sort)
list_sort(NULL, &plug->list, plug_rq_cmp);
list_splice_init(&plug->list, &list);

if (plug->should_sort) {
list_sort(NULL, &list, plug_rq_cmp);
plug->should_sort = 0;
}

q = NULL;
depth = 0;

/*
* Save and disable interrupts here, to avoid doing it for every
* queue lock we have to take.
*/
local_irq_save(flags);
while (!list_empty(&plug->list)) {
rq = list_entry_rq(plug->list.next);
while (!list_empty(&list)) {
rq = list_entry_rq(list.next);
list_del_init(&rq->queuelist);
BUG_ON(!(rq->cmd_flags & REQ_ON_PLUG));
BUG_ON(!rq->q);
if (rq->q != q) {
if (q) {
__blk_run_queue(q, false);
queue_unplugged(q, depth, force_kblockd);
spin_unlock(q->queue_lock);
}
q = rq->q;
depth = 0;
spin_lock(q->queue_lock);
}
rq->cmd_flags &= ~REQ_ON_PLUG;
Expand All @@ -2706,38 +2723,27 @@ static void flush_plug_list(struct blk_plug *plug)
__elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
else
__elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);

depth++;
}

if (q) {
__blk_run_queue(q, false);
queue_unplugged(q, depth, force_kblockd);
spin_unlock(q->queue_lock);
}

BUG_ON(!list_empty(&plug->list));
local_irq_restore(flags);
}

static void __blk_finish_plug(struct task_struct *tsk, struct blk_plug *plug)
{
flush_plug_list(plug);

if (plug == tsk->plug)
tsk->plug = NULL;
}
EXPORT_SYMBOL(blk_flush_plug_list);

void blk_finish_plug(struct blk_plug *plug)
{
if (plug)
__blk_finish_plug(current, plug);
}
EXPORT_SYMBOL(blk_finish_plug);
blk_flush_plug_list(plug, false);

void __blk_flush_plug(struct task_struct *tsk, struct blk_plug *plug)
{
__blk_finish_plug(tsk, plug);
tsk->plug = plug;
if (plug == current->plug)
current->plug = NULL;
}
EXPORT_SYMBOL(__blk_flush_plug);
EXPORT_SYMBOL(blk_finish_plug);

int __init blk_dev_init(void)
{
Expand Down
16 changes: 16 additions & 0 deletions block/blk-settings.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -790,6 +790,22 @@ void blk_queue_flush(struct request_queue *q, unsigned int flush)
}
EXPORT_SYMBOL_GPL(blk_queue_flush);

/**
* blk_queue_unplugged - register a callback for an unplug event
* @q: the request queue for the device
* @fn: the function to call
*
* Some stacked drivers may need to know when IO is dispatched on an
* unplug event. By registrering a callback here, they will be notified
* when someone flushes their on-stack queue plug. The function will be
* called with the queue lock held.
*/
void blk_queue_unplugged(struct request_queue *q, unplugged_fn *fn)
{
q->unplugged_fn = fn;
}
EXPORT_SYMBOL(blk_queue_unplugged);

static int __init blk_settings_init(void)
{
blk_max_low_pfn = max_low_pfn - 1;
Expand Down
3 changes: 1 addition & 2 deletions block/blk-sysfs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -498,7 +498,6 @@ int blk_register_queue(struct gendisk *disk)
{
int ret;
struct device *dev = disk_to_dev(disk);

struct request_queue *q = disk->queue;

if (WARN_ON(!q))
Expand All @@ -521,7 +520,7 @@ int blk_register_queue(struct gendisk *disk)
if (ret) {
kobject_uevent(&q->kobj, KOBJ_REMOVE);
kobject_del(&q->kobj);
blk_trace_remove_sysfs(disk_to_dev(disk));
blk_trace_remove_sysfs(dev);
kobject_put(&dev->kobj);
return ret;
}
Expand Down
9 changes: 6 additions & 3 deletions include/linux/blkdev.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -196,6 +196,7 @@ typedef void (request_fn_proc) (struct request_queue *q);
typedef int (make_request_fn) (struct request_queue *q, struct bio *bio);
typedef int (prep_rq_fn) (struct request_queue *, struct request *);
typedef void (unprep_rq_fn) (struct request_queue *, struct request *);
typedef void (unplugged_fn) (struct request_queue *);

struct bio_vec;
struct bvec_merge_data {
Expand Down Expand Up @@ -283,6 +284,7 @@ struct request_queue
rq_timed_out_fn *rq_timed_out_fn;
dma_drain_needed_fn *dma_drain_needed;
lld_busy_fn *lld_busy_fn;
unplugged_fn *unplugged_fn;

/*
* Dispatch queue sorting
Expand Down Expand Up @@ -841,6 +843,7 @@ extern void blk_queue_dma_alignment(struct request_queue *, int);
extern void blk_queue_update_dma_alignment(struct request_queue *, int);
extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
extern void blk_queue_rq_timed_out(struct request_queue *, rq_timed_out_fn *);
extern void blk_queue_unplugged(struct request_queue *, unplugged_fn *);
extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
extern void blk_queue_flush(struct request_queue *q, unsigned int flush);
extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
Expand All @@ -862,14 +865,14 @@ struct blk_plug {

extern void blk_start_plug(struct blk_plug *);
extern void blk_finish_plug(struct blk_plug *);
extern void __blk_flush_plug(struct task_struct *, struct blk_plug *);
extern void blk_flush_plug_list(struct blk_plug *, bool);

static inline void blk_flush_plug(struct task_struct *tsk)
{
struct blk_plug *plug = tsk->plug;

if (unlikely(plug))
__blk_flush_plug(tsk, plug);
if (plug)
blk_flush_plug_list(plug, true);
}

static inline bool blk_needs_flush_plug(struct task_struct *tsk)
Expand Down
25 changes: 6 additions & 19 deletions include/trace/events/block.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -401,49 +401,36 @@ TRACE_EVENT(block_plug,

DECLARE_EVENT_CLASS(block_unplug,

TP_PROTO(struct request_queue *q),
TP_PROTO(struct request_queue *q, unsigned int depth),

TP_ARGS(q),
TP_ARGS(q, depth),

TP_STRUCT__entry(
__field( int, nr_rq )
__array( char, comm, TASK_COMM_LEN )
),

TP_fast_assign(
__entry->nr_rq = q->rq.count[READ] + q->rq.count[WRITE];
__entry->nr_rq = depth;
memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
),

TP_printk("[%s] %d", __entry->comm, __entry->nr_rq)
);

/**
* block_unplug_timer - timed release of operations requests in queue to device driver
* @q: request queue to unplug
*
* Unplug the request queue @q because a timer expired and allow block
* operation requests to be sent to the device driver.
*/
DEFINE_EVENT(block_unplug, block_unplug_timer,

TP_PROTO(struct request_queue *q),

TP_ARGS(q)
);

/**
* block_unplug_io - release of operations requests in request queue
* @q: request queue to unplug
* @depth: number of requests just added to the queue
*
* Unplug request queue @q because device driver is scheduled to work
* on elements in the request queue.
*/
DEFINE_EVENT(block_unplug, block_unplug_io,

TP_PROTO(struct request_queue *q),
TP_PROTO(struct request_queue *q, unsigned int depth),

TP_ARGS(q)
TP_ARGS(q, depth)
);

/**
Expand Down
23 changes: 3 additions & 20 deletions kernel/trace/blktrace.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -850,32 +850,19 @@ static void blk_add_trace_plug(void *ignore, struct request_queue *q)
__blk_add_trace(bt, 0, 0, 0, BLK_TA_PLUG, 0, 0, NULL);
}

static void blk_add_trace_unplug_io(void *ignore, struct request_queue *q)
static void blk_add_trace_unplug_io(void *ignore, struct request_queue *q,
unsigned int depth)
{
struct blk_trace *bt = q->blk_trace;

if (bt) {
unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
__be64 rpdu = cpu_to_be64(pdu);
__be64 rpdu = cpu_to_be64(depth);

__blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_IO, 0,
sizeof(rpdu), &rpdu);
}
}

static void blk_add_trace_unplug_timer(void *ignore, struct request_queue *q)
{
struct blk_trace *bt = q->blk_trace;

if (bt) {
unsigned int pdu = q->rq.count[READ] + q->rq.count[WRITE];
__be64 rpdu = cpu_to_be64(pdu);

__blk_add_trace(bt, 0, 0, 0, BLK_TA_UNPLUG_TIMER, 0,
sizeof(rpdu), &rpdu);
}
}

static void blk_add_trace_split(void *ignore,
struct request_queue *q, struct bio *bio,
unsigned int pdu)
Expand Down Expand Up @@ -1015,8 +1002,6 @@ static void blk_register_tracepoints(void)
WARN_ON(ret);
ret = register_trace_block_plug(blk_add_trace_plug, NULL);
WARN_ON(ret);
ret = register_trace_block_unplug_timer(blk_add_trace_unplug_timer, NULL);
WARN_ON(ret);
ret = register_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
WARN_ON(ret);
ret = register_trace_block_split(blk_add_trace_split, NULL);
Expand All @@ -1033,7 +1018,6 @@ static void blk_unregister_tracepoints(void)
unregister_trace_block_bio_remap(blk_add_trace_bio_remap, NULL);
unregister_trace_block_split(blk_add_trace_split, NULL);
unregister_trace_block_unplug_io(blk_add_trace_unplug_io, NULL);
unregister_trace_block_unplug_timer(blk_add_trace_unplug_timer, NULL);
unregister_trace_block_plug(blk_add_trace_plug, NULL);
unregister_trace_block_sleeprq(blk_add_trace_sleeprq, NULL);
unregister_trace_block_getrq(blk_add_trace_getrq, NULL);
Expand Down Expand Up @@ -1348,7 +1332,6 @@ static const struct {
[__BLK_TA_COMPLETE] = {{ "C", "complete" }, blk_log_with_error },
[__BLK_TA_PLUG] = {{ "P", "plug" }, blk_log_plug },
[__BLK_TA_UNPLUG_IO] = {{ "U", "unplug_io" }, blk_log_unplug },
[__BLK_TA_UNPLUG_TIMER] = {{ "UT", "unplug_timer" }, blk_log_unplug },
[__BLK_TA_INSERT] = {{ "I", "insert" }, blk_log_generic },
[__BLK_TA_SPLIT] = {{ "X", "split" }, blk_log_split },
[__BLK_TA_BOUNCE] = {{ "B", "bounce" }, blk_log_generic },
Expand Down

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