[PATCH 05/12] block: Introduce PCI P2P flags for request and request queue

Logan Gunthorpe
2018-01-04T19:01:30Z

QUEUE_FLAG_PCI_P2P is introduced meaning a driver's request queue
supports targeting P2P memory.

REQ_PCI_P2P is introduced to indicate a particular bio request is
directed to/from PCI P2P memory. A request with this flag is not
accepted unless the corresponding queues have the QUEUE_FLAG_PCI_P2P
flag set.

Signed-off-by: Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
---
block/blk-core.c | 3 +++
include/linux/blk_types.h | 18 +++++++++++++++++-
include/linux/blkdev.h | 2 ++
3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index b8881750a3ac..f347c25731ff 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2141,6 +2141,9 @@ generic_make_request_checks(struct bio *bio)
if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q))
goto not_supported;

+ if ((bio->bi_opf & REQ_PCI_P2P) && !blk_queue_pci_p2p(q))
+ goto not_supported;
+
if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size))
goto end_io;

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 9e7d8bd776d2..8e1b4d643478 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -228,6 +228,10 @@ enum req_flag_bits {
__REQ_BACKGROUND, /* background IO */
__REQ_NOWAIT, /* Don't wait if request will block */

+#ifdef CONFIG_PCI_P2P
+ __REQ_PCI_P2P, /* request is to/from P2P memory */
+#endif
+
/* command specific flags for REQ_OP_WRITE_ZEROES: */
__REQ_NOUNMAP, /* do not free blocks when zeroing */

@@ -252,6 +256,18 @@ enum req_flag_bits {
#define REQ_BACKGROUND (1ULL << __REQ_BACKGROUND)
#define REQ_NOWAIT (1ULL << __REQ_NOWAIT)

+#ifdef CONFIG_PCI_P2P
+/*
+ * Currently SGLs do not support mixed P2P and regular memory so
+ * requests with P2P memory must not be merged.
+ */
+#define REQ_PCI_P2P (1ULL << __REQ_PCI_P2P)
+#define REQ_IS_PCI_P2P(req) ((req)->cmd_flags & REQ_PCI_P2P)
+#else
+#define REQ_PCI_P2P 0
+#define REQ_IS_PCI_P2P(req) 0
+#endif /* CONFIG_PCI_P2P */
+
#define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP)

#define REQ_DRV (1ULL << __REQ_DRV)
@@ -260,7 +276,7 @@ enum req_flag_bits {
(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)

#define REQ_NOMERGE_FLAGS \
- (REQ_NOMERGE | REQ_PREFLUSH | REQ_FUA)
+ (REQ_NOMERGE | REQ_PREFLUSH | REQ_FUA | REQ_PCI_P2P)

#define bio_op(bio) \
((bio)->bi_opf & REQ_OP_MASK)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0ce8a372d506..877b71dd1122 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -651,6 +651,7 @@ struct request_queue {
#define QUEUE_FLAG_SCSI_PASSTHROUGH 27 /* queue supports SCSI commands */
#define QUEUE_FLAG_QUIESCED 28 /* queue has been quiesced */
#define QUEUE_FLAG_PREEMPT_ONLY 29 /* only process REQ_PREEMPT requests */
+#define QUEUE_FLAG_PCI_P2P 30 /* device supports pci p2p requests */

#define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_SAME_COMP) | \
@@ -746,6 +747,7 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
#define blk_queue_dax(q) test_bit(QUEUE_FLAG_DAX, &(q)->queue_flags)
#define blk_queue_scsi_passthrough(q) \
test_bit(QUEUE_FLAG_SCSI_PASSTHROUGH, &(q)->queue_flags)
+#define blk_queue_pci_p2p(q) test_bit(QUEUE_FLAG_PCI_P2P, &(q)->queue_flags)

#define blk_noretry_request(rq) \
((rq)->cmd_flags & (REQ_FAILFAST_DEV|REQ_FAILFAST_TRANSPORT| \
--
2.11.0