linux-kernel - [PATCH 1/5] block: remove RQF_COPY

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Message-Id: <20200414074225.332324-2-hch@lst.de>
Date:   Tue, 14 Apr 2020 09:42:21 +0200
From:   Christoph Hellwig <hch@....de>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-ide@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: [PATCH 1/5] block: remove RQF_COPY_USER

The RQF_COPY_USER is set for bio where the passthrough request mapping
helpers decided that bounce buffering is required.  It is then used to
pad scatterlist for drivers that required it.  But given that
non-passthrough requests are per definition aligned, and directly mapped
pass-through request must be aligned it is not actually required at all.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 block/blk-map.c        | 9 +--------
 block/blk-merge.c      | 3 +--
 block/blk-mq-debugfs.c | 1 -
 include/linux/blkdev.h | 2 --
 4 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/block/blk-map.c b/block/blk-map.c
index b72c361911a4..b6fa343fea9f 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -654,8 +654,6 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 			bio = rq->bio;
 	} while (iov_iter_count(&i));
 
-	if (!bio_flagged(bio, BIO_USER_MAPPED))
-		rq->rq_flags |= RQF_COPY_USER;
 	return 0;
 
 unmap_rq:
@@ -731,7 +729,6 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 {
 	int reading = rq_data_dir(rq) == READ;
 	unsigned long addr = (unsigned long) kbuf;
-	int do_copy = 0;
 	struct bio *bio, *orig_bio;
 	int ret;
 
@@ -740,8 +737,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 	if (!len || !kbuf)
 		return -EINVAL;
 
-	do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf);
-	if (do_copy)
+	if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf))
 		bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
 	else
 		bio = bio_map_kern(q, kbuf, len, gfp_mask);
@@ -752,9 +748,6 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 	bio->bi_opf &= ~REQ_OP_MASK;
 	bio->bi_opf |= req_op(rq);
 
-	if (do_copy)
-		rq->rq_flags |= RQF_COPY_USER;
-
 	orig_bio = bio;
 	ret = blk_rq_append_bio(rq, &bio);
 	if (unlikely(ret)) {
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 1534ed736363..99c9759f3a8a 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -532,8 +532,7 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
 	else if (rq->bio)
 		nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg);
 
-	if (unlikely(rq->rq_flags & RQF_COPY_USER) &&
-	    (blk_rq_bytes(rq) & q->dma_pad_mask)) {
+	if (blk_rq_bytes(rq) && (blk_rq_bytes(rq) & q->dma_pad_mask)) {
 		unsigned int pad_len =
 			(q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1;
 
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index b3f2ba483992..96b7a35c898a 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -292,7 +292,6 @@ static const char *const rqf_name[] = {
 	RQF_NAME(MQ_INFLIGHT),
 	RQF_NAME(DONTPREP),
 	RQF_NAME(PREEMPT),
-	RQF_NAME(COPY_USER),
 	RQF_NAME(FAILED),
 	RQF_NAME(QUIET),
 	RQF_NAME(ELVPRIV),
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 32868fbedc9e..76da162b6ae9 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -82,8 +82,6 @@ typedef __u32 __bitwise req_flags_t;
 /* set for "ide_preempt" requests and also for requests for which the SCSI
    "quiesce" state must be ignored. */
 #define RQF_PREEMPT		((__force req_flags_t)(1 << 8))
-/* contains copies of user pages */
-#define RQF_COPY_USER		((__force req_flags_t)(1 << 9))
 /* vaguely specified driver internal error.  Ignored by the block layer */
 #define RQF_FAILED		((__force req_flags_t)(1 << 10))
 /* don't warn about errors */
-- 
2.25.1