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block: cleanup the block plug helper functions
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It's a bit of a mess currently. task->plug is being cleared
and reset in __blk_finish_plug(), and blk_finish_plug() is
testing for a NULL plug which cannot happen even from schedule()
anymore since it uses blk_needs_flush_plug() to determine
whether to call into this function at all.

So get rid of some of the cruft.

Signed-off-by: Jens Axboe <[email protected]>
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Christoph Hellwig authored and Jens Axboe committed Apr 15, 2011
1 parent 80656b6 commit 88b996c
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Showing 2 changed files with 9 additions and 21 deletions.
24 changes: 6 additions & 18 deletions block/blk-core.c
Original file line number Diff line number Diff line change
Expand Up @@ -2671,7 +2671,7 @@ static void queue_unplugged(struct request_queue *q, unsigned int depth)
q->unplugged_fn(q);
}

static void flush_plug_list(struct blk_plug *plug)
void blk_flush_plug_list(struct blk_plug *plug)
{
struct request_queue *q;
unsigned long flags;
Expand Down Expand Up @@ -2733,28 +2733,16 @@ static void flush_plug_list(struct blk_plug *plug)

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);

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)
{
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6 changes: 3 additions & 3 deletions include/linux/blkdev.h
Original file line number Diff line number Diff line change
Expand Up @@ -865,14 +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 *);

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);
}

static inline bool blk_needs_flush_plug(struct task_struct *tsk)
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