On 10/29/18 1:10 AM, Hannes Reinecke wrote:
> On 10/25/18 11:10 PM, Jens Axboe wrote:
>> Nobody sets the helper, so we always return 0. Kill it.
>>
>> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
>> ---
>> block/blk-core.c | 28 ----------------------------
>> block/blk-settings.c | 6 ------
>> drivers/md/dm-mpath.c | 4 +---
>> include/linux/blkdev.h | 4 ----
>> 4 files changed, 1 insertion(+), 41 deletions(-)
>>
>> diff --git a/block/blk-core.c b/block/blk-core.c
>> index 4c39c7865f9c..dd1328f4dc31 100644
>> --- a/block/blk-core.c
>> +++ b/block/blk-core.c
>> @@ -1795,34 +1795,6 @@ void rq_flush_dcache_pages(struct request *rq)
>> EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
>> #endif
>>
>> -/**
>> - * blk_lld_busy - Check if underlying low-level drivers of a device are busy
>> - * @q : the queue of the device being checked
>> - *
>> - * Description:
>> - * Check if underlying low-level drivers of a device are busy.
>> - * If the drivers want to export their busy state, they must set own
>> - * exporting function using blk_queue_lld_busy() first.
>> - *
>> - * Basically, this function is used only by request stacking drivers
>> - * to stop dispatching requests to underlying devices when underlying
>> - * devices are busy. This behavior helps more I/O merging on the queue
>> - * of the request stacking driver and prevents I/O throughput regression
>> - * on burst I/O load.
>> - *
>> - * Return:
>> - * 0 - Not busy (The request stacking driver should dispatch request)
>> - * 1 - Busy (The request stacking driver should stop dispatching request)
>> - */
>> -int blk_lld_busy(struct request_queue *q)
>> -{
>> - if (q->lld_busy_fn)
>> - return q->lld_busy_fn(q);
>> -
>> - return 0;
>> -}
>> -EXPORT_SYMBOL_GPL(blk_lld_busy);
>> -
>> /**
>> * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
>> * @rq: the clone request to be cleaned up
>> diff --git a/block/blk-settings.c b/block/blk-settings.c
>> index 3c5da75c2def..1895f499bbe5 100644
>> --- a/block/blk-settings.c
>> +++ b/block/blk-settings.c
>> @@ -32,12 +32,6 @@ void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout)
>> }
>> EXPORT_SYMBOL_GPL(blk_queue_rq_timeout);
>>
>> -void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn)
>> -{
>> - q->lld_busy_fn = fn;
>> -}
>> -EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
>> -
>> /**
>> * blk_set_default_limits - reset limits to default values
>> * @lim: the queue_limits structure to reset
>> diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
>> index a24ed3973e7c..4d736e0fd67f 100644
>> --- a/drivers/md/dm-mpath.c
>> +++ b/drivers/md/dm-mpath.c
>> @@ -1936,9 +1936,7 @@ static int multipath_iterate_devices(struct dm_target *ti,
>>
>> static int pgpath_busy(struct pgpath *pgpath)
>> {
>> - struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
>> -
>> - return blk_lld_busy(q);
>> + return 0;
>> }
>>
>> /*
> Actually, I'm not quite sure this is correct; dm-mpath needs to return a
> busy status (via the '->busy' callback) to allow for back-pressure on
> the upper layers.
> Just disabling the callback will disable this.
> Shouldn't we check if the tagmap is busy here?
Mike? We can pretty easily make it just check for busy tags.
--
Jens Axboe
