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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: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2015-05-22 17:13:41 -04:00 committed by Jens Axboe
parent dfb8ae5678
commit ec8a6f2643
3 changed files with 49 additions and 32 deletions
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14
include/linux/backing-dev-defs.h
View File

@ -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 */

45
include/linux/backing-dev.h
View File

@ -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)
{
struct backing_dev_info *bdi = wb->bdi;
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);
}
static inline int bdi_rw_congested(struct backing_dev_info *bdi)
{
return bdi_congested(bdi, (1 << WB_sync_congested) |
(1 << WB_async_congested));
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 */

22
mm/backing-dev.c
View File

@ -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();