@@ -956,11 +956,19 @@ static blk_qc_t __submit_bio(struct bio *bio)
* bio_list_on_stack[0] contains bios submitted by the current ->submit_bio.
* bio_list_on_stack[1] contains bios that were submitted before the current
* ->submit_bio_bio, but that haven't been processed yet.
+ *
+ * Return:
+ * - BLK_QC_T_NONE, no need for IO polling.
+ * - BLK_QC_T_BIO_POLL_ALL, @bio gets split and enqueued into multi hw queues.
+ * - Otherwise, @bio is not split, returning the pointer to the corresponding
+ * hw queue that the bio enqueued into as the returned cookie.
*/
static blk_qc_t __submit_bio_noacct(struct bio *bio)
{
struct bio_list bio_list_on_stack[2];
blk_qc_t ret = BLK_QC_T_NONE;
+ struct request_queue *top_q = bio->bi_disk->queue;
+ bool poll_on = test_bit(QUEUE_FLAG_POLL, &top_q->queue_flags);
BUG_ON(bio->bi_next);
@@ -968,6 +976,7 @@ static blk_qc_t __submit_bio_noacct(struct bio *bio)
current->bio_list = bio_list_on_stack;
do {
+ blk_qc_t cookie;
struct request_queue *q = bio->bi_disk->queue;
struct bio_list lower, same;
@@ -980,7 +989,23 @@ static blk_qc_t __submit_bio_noacct(struct bio *bio)
bio_list_on_stack[1] = bio_list_on_stack[0];
bio_list_init(&bio_list_on_stack[0]);
- ret = __submit_bio(bio);
+ cookie = __submit_bio(bio);
+
+ if (poll_on && blk_qc_t_valid(cookie)) {
+ unsigned int queue_num = blk_qc_t_to_queue_num(cookie);
+ struct blk_mq_hw_ctx *hctx = q->queue_hw_ctx[queue_num];
+
+ cookie = (blk_qc_t)hctx;
+
+ if (!blk_qc_t_valid(ret)) {
+ /* set initial value */
+ ret = cookie;
+ } else if (ret != cookie) {
+ /* bio gets split and enqueued to multi hctxs */
+ ret = BLK_QC_T_BIO_POLL_ALL;
+ poll_on = false;
+ }
+ }
/*
* Sort new bios into those for a lower level and those for the
@@ -1003,6 +1028,7 @@ static blk_qc_t __submit_bio_noacct(struct bio *bio)
} while ((bio = bio_list_pop(&bio_list_on_stack[0])));
current->bio_list = NULL;
+
return ret;
}
@@ -1142,7 +1168,15 @@ static int blk_bio_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
do {
int ret;
- ret = disk->fops->poll(q, cookie);
+ if (unlikely(blk_qc_t_is_poll_multi(cookie)))
+ ret = disk->fops->poll(q, cookie);
+ else {
+ struct blk_mq_hw_ctx *hctx = (struct blk_mq_hw_ctx *)cookie;
+ struct request_queue *target_q = hctx->queue;
+
+ ret = blk_mq_poll_hctx(target_q, hctx);
+ }
+
if (ret > 0) {
__set_current_state(TASK_RUNNING);
return ret;
@@ -557,6 +557,14 @@ static inline bool blk_qc_t_is_internal(blk_qc_t cookie)
return (cookie & BLK_QC_T_INTERNAL) != 0;
}
+/* Macros for blk_qc_t used for bio-based polling */
+#define BLK_QC_T_BIO_POLL_ALL 1U
+
+static inline bool blk_qc_t_is_poll_multi(blk_qc_t cookie)
+{
+ return cookie & BLK_QC_T_BIO_POLL_ALL;
+}
+
struct blk_rq_stat {
u64 mean;
u64 min;
@@ -126,7 +126,7 @@ typedef u64 sector_t;
typedef u64 blkcnt_t;
/* cookie used for IO polling */
-typedef unsigned int blk_qc_t;
+typedef uintptr_t blk_qc_t;
/*
* The type of an index into the pagecache.
Offer one fastpath for bio-based polling when bio submitted to dm device is not split. In this case, there will be only one bio submitted to only one polling hw queue of one underlying mq device, and thus we don't need to track all split bios or iterate through all polling hw queues. The pointer to the polling hw queue the bio submitted to is returned here as the returned cookie. In this case, the polling routine will call mq_ops->poll() directly with the hw queue converted from the input cookie. If the original bio submitted to dm device is split to multiple bios and thus submitted to multiple polling hw queues, the polling routine will fall back to iterating all hw queues (in polling mode) of all underlying mq devices. Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com> --- block/blk-core.c | 38 ++++++++++++++++++++++++++++++++++++-- include/linux/blk_types.h | 8 ++++++++ include/linux/types.h | 2 +- 3 files changed, 45 insertions(+), 3 deletions(-)