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Commit ec8a6f26 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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writeback: make congestion functions per bdi_writeback 



Currently, all congestion functions take bdi (backing_dev_info) and
always operate on the root wb (bdi->wb) and the congestion state from
the block layer is propagated only for the root blkcg.  This patch
introduces {set|clear}_wb_congested() and wb_congested() which take a
bdi_writeback_congested and bdi_writeback respectively.  The bdi
counteparts are now wrappers invoking the wb based functions on
@bdi->wb.

While converting clear_bdi_congested() to clear_wb_congested(), the
local variable declaration order between @wqh and @bit is swapped for
cosmetic reason.

This patch just adds the new wb based functions.  The following
patches will apply them.

v2: Updated for bdi_writeback_congested.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent dfb8ae56

include/linux/backing-dev-defs.h

+12 −2
Original line number Diff line number Diff line
@@ -163,7 +163,17 @@ enum { 
	BLK_RW_SYNC	= 1,

};



void clear_bdi_congested(struct backing_dev_info *bdi, int sync);

void set_bdi_congested(struct backing_dev_info *bdi, int sync);

void clear_wb_congested(struct bdi_writeback_congested *congested, int sync);

void set_wb_congested(struct bdi_writeback_congested *congested, int sync);



static inline void clear_bdi_congested(struct backing_dev_info *bdi, int sync)

{

	clear_wb_congested(bdi->wb.congested, sync);

}



static inline void set_bdi_congested(struct backing_dev_info *bdi, int sync)

{

	set_wb_congested(bdi->wb.congested, sync);

}



#endif	/* __LINUX_BACKING_DEV_DEFS_H */

include/linux/backing-dev.h

+26 −19
Original line number Diff line number Diff line
@@ -167,27 +167,13 @@ static inline struct backing_dev_info *inode_to_bdi(struct inode *inode) 
	return sb->s_bdi;

}



static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)

static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)

{

	if (bdi->congested_fn)

		return bdi->congested_fn(bdi->congested_data, bdi_bits);

	return (bdi->wb.congested->state & bdi_bits);

}



static inline int bdi_read_congested(struct backing_dev_info *bdi)

{

	return bdi_congested(bdi, 1 << WB_sync_congested);

}



static inline int bdi_write_congested(struct backing_dev_info *bdi)

{

	return bdi_congested(bdi, 1 << WB_async_congested);

}

	struct backing_dev_info *bdi = wb->bdi;



static inline int bdi_rw_congested(struct backing_dev_info *bdi)

{

	return bdi_congested(bdi, (1 << WB_sync_congested) |

				  (1 << WB_async_congested));

	if (bdi->congested_fn)

		return bdi->congested_fn(bdi->congested_data, cong_bits);

	return wb->congested->state & cong_bits;

}



long congestion_wait(int sync, long timeout);
@@ -454,4 +440,25 @@ static inline void wb_blkcg_offline(struct blkcg *blkcg) 


#endif	/* CONFIG_CGROUP_WRITEBACK */



static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)

{

	return wb_congested(&bdi->wb, cong_bits);

}



static inline int bdi_read_congested(struct backing_dev_info *bdi)

{

	return bdi_congested(bdi, 1 << WB_sync_congested);

}



static inline int bdi_write_congested(struct backing_dev_info *bdi)

{

	return bdi_congested(bdi, 1 << WB_async_congested);

}



static inline int bdi_rw_congested(struct backing_dev_info *bdi)

{

	return bdi_congested(bdi, (1 << WB_sync_congested) |

				  (1 << WB_async_congested));

}



#endif	/* _LINUX_BACKING_DEV_H */

mm/backing-dev.c

+11 −11
Original line number Diff line number Diff line
@@ -896,31 +896,31 @@ static wait_queue_head_t congestion_wqh[2] = { 
		__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),

		__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])

	};

static atomic_t nr_bdi_congested[2];

static atomic_t nr_wb_congested[2];



void clear_bdi_congested(struct backing_dev_info *bdi, int sync)

void clear_wb_congested(struct bdi_writeback_congested *congested, int sync)

{

	enum wb_state bit;

	wait_queue_head_t *wqh = &congestion_wqh[sync];

	enum wb_state bit;



	bit = sync ? WB_sync_congested : WB_async_congested;

	if (test_and_clear_bit(bit, &bdi->wb.congested->state))

		atomic_dec(&nr_bdi_congested[sync]);

	if (test_and_clear_bit(bit, &congested->state))

		atomic_dec(&nr_wb_congested[sync]);

	smp_mb__after_atomic();

	if (waitqueue_active(wqh))

		wake_up(wqh);

}

EXPORT_SYMBOL(clear_bdi_congested);

EXPORT_SYMBOL(clear_wb_congested);



void set_bdi_congested(struct backing_dev_info *bdi, int sync)

void set_wb_congested(struct bdi_writeback_congested *congested, int sync)

{

	enum wb_state bit;



	bit = sync ? WB_sync_congested : WB_async_congested;

	if (!test_and_set_bit(bit, &bdi->wb.congested->state))

		atomic_inc(&nr_bdi_congested[sync]);

	if (!test_and_set_bit(bit, &congested->state))

		atomic_inc(&nr_wb_congested[sync]);

}

EXPORT_SYMBOL(set_bdi_congested);

EXPORT_SYMBOL(set_wb_congested);



/**

 * congestion_wait - wait for a backing_dev to become uncongested
@@ -979,7 +979,7 @@ long wait_iff_congested(struct zone *zone, int sync, long timeout) 
	 * encountered in the current zone, yield if necessary instead

	 * of sleeping on the congestion queue

	 */

	if (atomic_read(&nr_bdi_congested[sync]) == 0 ||

	if (atomic_read(&nr_wb_congested[sync]) == 0 ||

	    !test_bit(ZONE_CONGESTED, &zone->flags)) {

		cond_resched();