[dm-devel] [PATCH 6/8] dm: don't grab target io reference in dm_zone_map_bio

[Ming Lei]

dm_zone_map_bio() is only called from __map_bio in which the io's
reference is grabbed already, and the reference won't be released
until the bio is submitted, so no necessary to do it dm_zone_map_bio
any more.

Reviewed-by: Damien Le Moal <damien.lemoal at opensource.wdc.com>
Tested-by: Damien Le Moal <damien.lemoal at opensource.wdc.com>
Signed-off-by: Ming Lei <ming.lei at redhat.com>
---
 drivers/md/dm-core.h |  7 -------
 drivers/md/dm-zone.c | 10 ----------
 drivers/md/dm.c      |  7 ++++++-
 3 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index aefb080c230d..811c0ccbc63d 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -283,13 +283,6 @@ static inline void dm_io_set_flag(struct dm_io *io, unsigned int bit)
 	io->flags |= (1U << bit);
 }
 
-static inline void dm_io_inc_pending(struct dm_io *io)
-{
-	atomic_inc(&io->io_count);
-}
-
-void dm_io_dec_pending(struct dm_io *io, blk_status_t error);
-
 static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
 {
 	return &container_of(kobj, struct dm_kobject_holder, kobj)->completion;
diff --git a/drivers/md/dm-zone.c b/drivers/md/dm-zone.c
index c1ca9be4b79e..85d3c158719f 100644
--- a/drivers/md/dm-zone.c
+++ b/drivers/md/dm-zone.c
@@ -545,13 +545,6 @@ int dm_zone_map_bio(struct dm_target_io *tio)
 		return DM_MAPIO_KILL;
 	}
 
-	/*
-	 * The target map function may issue and complete the IO quickly.
-	 * Take an extra reference on the IO to make sure it does disappear
-	 * until we run dm_zone_map_bio_end().
-	 */
-	dm_io_inc_pending(io);
-
 	/* Let the target do its work */
 	r = ti->type->map(ti, clone);
 	switch (r) {
@@ -580,9 +573,6 @@ int dm_zone_map_bio(struct dm_target_io *tio)
 		break;
 	}
 
-	/* Drop the extra reference on the IO */
-	dm_io_dec_pending(io, sts);
-
 	if (sts != BLK_STS_OK)
 		return DM_MAPIO_KILL;
 
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index df1d013fb793..3c3ba6b4e19b 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -937,11 +937,16 @@ static inline bool dm_tio_is_normal(struct dm_target_io *tio)
 		!dm_tio_flagged(tio, DM_TIO_IS_DUPLICATE_BIO));
 }
 
+static void dm_io_inc_pending(struct dm_io *io)
+{
+	atomic_inc(&io->io_count);
+}
+
 /*
  * Decrements the number of outstanding ios that a bio has been
  * cloned into, completing the original io if necc.
  */
-void dm_io_dec_pending(struct dm_io *io, blk_status_t error)
+static void dm_io_dec_pending(struct dm_io *io, blk_status_t error)
 {
 	/* Push-back supersedes any I/O errors */
 	if (unlikely(error)) {
-- 
2.31.1