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blk-mq: make blk_abort_request() trigger timeout path

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With issue/complete and timeout paths now using the generation number
and state based synchronization, blk_abort_request() is the only one
which depends on REQ_ATOM_COMPLETE for arbitrating completion.

There's no reason for blk_abort_request() to be a completely separate
path.  This patch makes blk_abort_request() piggyback on the timeout
path instead of trying to terminate the request directly.

This removes the last dependency on REQ_ATOM_COMPLETE in blk-mq.

Note that this makes blk_abort_request() asynchronous - it initiates
abortion but the actual termination will happen after a short while,
even when the caller owns the request.  AFAICS, SCSI and ATA should be
fine with that and I think mtip32xx and dasd should be safe but not
completely sure.  It'd be great if people who know the drivers take a
look.

v2: - Add comment explaining the lack of synchronization around
      ->deadline update as requested by Bart.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Asai Thambi SP <asamymuthupa@micron.com>
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Jan Hoeppner <hoeppner@linux.vnet.ibm.com>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2018-01-09 08:29:50 -08:00 committed by Jens Axboe
parent 67818d2573
commit 358f70da49
3 changed files with 10 additions and 7 deletions
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2
block/blk-mq.c
View File

@ -820,7 +820,7 @@ struct blk_mq_timeout_data {
unsigned int nr_expired;
};
void blk_mq_rq_timed_out(struct request *req, bool reserved)
static void blk_mq_rq_timed_out(struct request *req, bool reserved)
{
const struct blk_mq_ops *ops = req->q->mq_ops;
enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;

2
block/blk-mq.h
View File

@ -94,8 +94,6 @@ extern int blk_mq_sysfs_register(struct request_queue *q);
extern void blk_mq_sysfs_unregister(struct request_queue *q);
extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);
extern void blk_mq_rq_timed_out(struct request *req, bool reserved);
void blk_mq_release(struct request_queue *q);
/**

13
block/blk-timeout.c
View File

@ -156,12 +156,17 @@ void blk_timeout_work(struct work_struct *work)
*/
void blk_abort_request(struct request *req)
{
if (blk_mark_rq_complete(req))
return;
if (req->q->mq_ops) {
blk_mq_rq_timed_out(req, false);
/*
* All we need to ensure is that timeout scan takes place
* immediately and that scan sees the new timeout value.
* No need for fancy synchronizations.
*/
req->deadline = jiffies;
mod_timer(&req->q->timeout, 0);
} else {
if (blk_mark_rq_complete(req))
return;
blk_delete_timer(req);
blk_rq_timed_out(req);
}