rd_hint is a bitmap for stacked layer support(see patch 4/9),
set a bit to 1 means already read from the corresponding mirror device.
rd_hint will be set properly recording read i/o went to which real device
during end_bio().
If the upper layer want to retry other mirrors, just preserve the returned
bi_rd_hint and resubmit bio.
The upper layer e.g fs can set bitmap_zero(rd_hint) if don't care about alt
mirror device retry feature which is also the default setting.
Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
Documentation/block/biodoc.txt | 3 +++
block/bio.c | 1 +
block/blk-core.c | 1 +
block/blk-merge.c | 6 ++++++
block/bounce.c | 1 +
drivers/md/raid1.c | 1 +
include/linux/blk_types.h | 1 +
include/linux/blkdev.h | 1 +
8 files changed, 15 insertions(+)
diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index ac18b488cb5e..c6b5dfc9314b 100644
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -430,6 +430,7 @@ struct bio {
struct bio *bi_next; /* request queue link */
struct block_device *bi_bdev; /* target device */
unsigned long bi_flags; /* status, command, etc */
+ DECLARE_BITMAP(bi_rd_hint, BLKDEV_MAX_MIRRORS); /* bio read hint */
unsigned long bi_opf; /* low bits: r/w, high: priority */
unsigned int bi_vcnt; /* how may bio_vec's */
@@ -464,6 +465,8 @@ With this multipage bio design:
(e.g a 1MB bio_vec needs to be handled in max 128kB chunks for IDE)
[TBD: Should preferably also have a bi_voffset and bi_vlen to avoid modifying
bi_offset an len fields]
+- bi_rd_hint is an in/out bitmap parameter, set a bit to 1 means already read
+ from the corresponding mirror device.
(*) unrelated merges -- a request ends up containing two or more bios that
didn't originate from the same place.
diff --git a/block/bio.c b/block/bio.c
index 4db1008309ed..0e97d75edbd4 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -606,6 +606,7 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
bio->bi_opf = bio_src->bi_opf;
bio->bi_ioprio = bio_src->bi_ioprio;
bio->bi_write_hint = bio_src->bi_write_hint;
+ bitmap_copy(bio->bi_rd_hint, bio_src->bi_rd_hint, BLKDEV_MAX_MIRRORS);
bio->bi_iter = bio_src->bi_iter;
bio->bi_io_vec = bio_src->bi_io_vec;
diff --git a/block/blk-core.c b/block/blk-core.c
index b838c6dc5357..c93162b7140c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -742,6 +742,7 @@ void blk_init_request_from_bio(struct request *req, struct bio *bio)
req->__sector = bio->bi_iter.bi_sector;
req->ioprio = bio_prio(bio);
req->write_hint = bio->bi_write_hint;
+ bitmap_copy(req->rd_hint, bio->bi_rd_hint, BLKDEV_MAX_MIRRORS);
blk_rq_bio_prep(req->q, req, bio);
}
EXPORT_SYMBOL_GPL(blk_init_request_from_bio);
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 71e9ac03f621..58982a80eca8 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -745,6 +745,9 @@ static struct request *attempt_merge(struct request_queue *q,
if (req->write_hint != next->write_hint)
return NULL;
+ if (!bitmap_equal(req->rd_hint, next->rd_hint, BLKDEV_MAX_MIRRORS))
+ return NULL;
+
if (req->ioprio != next->ioprio)
return NULL;
@@ -877,6 +880,9 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
if (rq->write_hint != bio->bi_write_hint)
return false;
+ if (!bitmap_equal(rq->rd_hint, bio->bi_rd_hint, BLKDEV_MAX_MIRRORS))
+ return false;
+
if (rq->ioprio != bio_prio(bio))
return false;
diff --git a/block/bounce.c b/block/bounce.c
index ffb9e9ecfa7e..fba66e06b735 100644
--- a/block/bounce.c
+++ b/block/bounce.c
@@ -250,6 +250,7 @@ static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
bio->bi_opf = bio_src->bi_opf;
bio->bi_ioprio = bio_src->bi_ioprio;
bio->bi_write_hint = bio_src->bi_write_hint;
+ bitmap_copy(bio->bi_rd_hint, bio_src->bi_rd_hint, BLKDEV_MAX_MIRRORS);
bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 1d54109071cc..1e5a51f22332 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1103,6 +1103,7 @@ static void alloc_behind_master_bio(struct r1bio *r1_bio,
}
behind_bio->bi_write_hint = bio->bi_write_hint;
+ bitmap_copy(behind_bio->bi_rd_hint, bio->bi_rd_hint, BLKDEV_MAX_MIRRORS);
while (i < vcnt && size) {
struct page *page;
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index d66bf5f32610..49bdd96e2623 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -151,6 +151,7 @@ struct bio {
unsigned short bi_flags; /* status, etc and bvec pool number */
unsigned short bi_ioprio;
unsigned short bi_write_hint;
+ DECLARE_BITMAP(bi_rd_hint, BLKDEV_MAX_MIRRORS);
blk_status_t bi_status;
u8 bi_partno;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0191dc4d3f2d..0a1e93b282c4 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -214,6 +214,7 @@ struct request {
#endif
unsigned short write_hint;
+ DECLARE_BITMAP(rd_hint, BLKDEV_MAX_MIRRORS);
unsigned short ioprio;
void *special; /* opaque pointer available for LLD use */
--
2.17.1
