From: Robin Dong <sanbai@xxxxxxxxxx>
When trying to modify flashcache to request based (current it's bio based), we need
to make request from bios by ourselves, but dm_io() will submit these bios directly,
so we propose to modify the dm_io() to return bios instead of submiting it.
This could also improve the flexibility of dm_io().
Signed-off-by: Robin Dong <sanbai@xxxxxxxxxx>
---
drivers/md/dm.c | 11 +++++++++++
include/linux/device-mapper.h | 3 +++
2 files changed, 14 insertions(+), 0 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 4e09b6f..bf6e3bb 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1459,11 +1459,22 @@ static int dm_request_based(struct mapped_device *md)
static void dm_request(struct request_queue *q, struct bio *bio)
{
struct mapped_device *md = q->queuedata;
+ struct dm_table *map = dm_get_live_table(md);
+ struct dm_target *ti = dm_table_find_target(map, bio->bi_sector);
+
+ if (ti->type->mk_rq) {
+ ti->type->mk_rq(ti, q, bio);
+ goto out;
+ }
if (dm_request_based(md))
blk_queue_bio(q, bio);
else
_dm_request(q, bio);
+
+out:
+ dm_table_put(map);
+ return;
}
void dm_dispatch_request(struct request *rq)
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 38d27a1..2386389 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -50,6 +50,8 @@ typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
union map_info *map_context);
typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
union map_info *map_context);
+typedef int (*dm_make_request_fn) (struct dm_target *ti,
+ struct request_queue *q, struct bio *bio);
/*
* Returns:
@@ -136,6 +138,7 @@ struct target_type {
dm_dtr_fn dtr;
dm_map_fn map;
dm_map_request_fn map_rq;
+ dm_make_request_fn mk_rq;
dm_endio_fn end_io;
dm_request_endio_fn rq_end_io;
dm_presuspend_fn presuspend;
--
1.7.1
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