Re: [PATCH 4/7] block: pass explicit gfp_t to get_request

[Hannes Reinecke]

On Mon,  9 Apr 2018 17:39:13 +0200
Christoph Hellwig  wrote:

> blk_old_get_request already has it at hand, and in blk_queue_bio,
> which is the fast path, it is constant.
> 
> Signed-off-by: Christoph Hellwig 
> ---
>  block/blk-core.c  | 14 +++---
>  drivers/scsi/scsi_error.c |  4 
>  2 files changed, 7 insertions(+), 11 deletions(-)
> 
Reviewed-by: Hannes Reinecke 

Cheers,

Hannes

[PATCH 4/7] block: pass explicit gfp_t to get_request

[Christoph Hellwig]

blk_old_get_request already has it at hand, and in blk_queue_bio, which
is the fast path, it is constant.

Signed-off-by: Christoph Hellwig 
---
 block/blk-core.c  | 14 +++---
 drivers/scsi/scsi_error.c |  4 
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 9002b4b34930..16ff472233ba 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1333,6 +1333,7 @@ int blk_update_nr_requests(struct request_queue *q, 
unsigned int nr)
  * @op: operation and flags
  * @bio: bio to allocate request for (can be %NULL)
  * @flags: BLQ_MQ_REQ_* flags
+ * @gfp_mask: allocator flags
  *
  * Get a free request from @q.  This function may fail under memory
  * pressure or if @q is dead.
@@ -1342,7 +1343,7 @@ int blk_update_nr_requests(struct request_queue *q, 
unsigned int nr)
  * Returns request pointer on success, with @q->queue_lock *not held*.
  */
 static struct request *__get_request(struct request_list *rl, unsigned int op,
-struct bio *bio, blk_mq_req_flags_t flags)
+   struct bio *bio, blk_mq_req_flags_t flags, gfp_t gfp_mask)
 {
struct request_queue *q = rl->q;
struct request *rq;
@@ -1351,8 +1352,6 @@ static struct request *__get_request(struct request_list 
*rl, unsigned int op,
struct io_cq *icq = NULL;
const bool is_sync = op_is_sync(op);
int may_queue;
-   gfp_t gfp_mask = flags & BLK_MQ_REQ_NOWAIT ? GFP_ATOMIC :
-__GFP_DIRECT_RECLAIM;
req_flags_t rq_flags = RQF_ALLOCED;
 
lockdep_assert_held(q->queue_lock);
@@ -1516,6 +1515,7 @@ static struct request *__get_request(struct request_list 
*rl, unsigned int op,
  * @op: operation and flags
  * @bio: bio to allocate request for (can be %NULL)
  * @flags: BLK_MQ_REQ_* flags.
+ * @gfp: allocator flags
  *
  * Get a free request from @q.  If %BLK_MQ_REQ_NOWAIT is set in @flags,
  * this function keeps retrying under memory pressure and fails iff @q is dead.
@@ -1525,7 +1525,7 @@ static struct request *__get_request(struct request_list 
*rl, unsigned int op,
  * Returns request pointer on success, with @q->queue_lock *not held*.
  */
 static struct request *get_request(struct request_queue *q, unsigned int op,
-  struct bio *bio, blk_mq_req_flags_t flags)
+   struct bio *bio, blk_mq_req_flags_t flags, gfp_t gfp)
 {
const bool is_sync = op_is_sync(op);
DEFINE_WAIT(wait);
@@ -1537,7 +1537,7 @@ static struct request *get_request(struct request_queue 
*q, unsigned int op,
 
rl = blk_get_rl(q, bio);/* transferred to @rq on success */
 retry:
-   rq = __get_request(rl, op, bio, flags);
+   rq = __get_request(rl, op, bio, flags, gfp);
if (!IS_ERR(rq))
return rq;
 
@@ -1591,7 +1591,7 @@ static struct request *blk_old_get_request(struct 
request_queue *q,
if (ret)
return ERR_PTR(ret);
spin_lock_irq(q->queue_lock);
-   rq = get_request(q, op, NULL, flags);
+   rq = get_request(q, op, NULL, flags, gfp_mask);
if (IS_ERR(rq)) {
spin_unlock_irq(q->queue_lock);
blk_queue_exit(q);
@@ -2057,7 +2057,7 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, 
struct bio *bio)
 * Returns with the queue unlocked.
 */
blk_queue_enter_live(q);
-   req = get_request(q, bio->bi_opf, bio, 0);
+   req = get_request(q, bio->bi_opf, bio, 0, __GFP_DIRECT_RECLAIM);
if (IS_ERR(req)) {
blk_queue_exit(q);
__wbt_done(q->rq_wb, wb_acct);
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 61d280f560df..b36e73090018 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1933,10 +1933,6 @@ static void scsi_eh_lock_door(struct scsi_device *sdev)
struct request *req;
struct scsi_request *rq;
 
-   /*
-* blk_get_request with GFP_KERNEL (__GFP_RECLAIM) sleeps until a
-* request becomes available
-*/
req = blk_get_request(sdev->request_queue, REQ_OP_SCSI_IN, 0);
if (IS_ERR(req))
return;
-- 
2.16.3