This function can be used if the target needs to receive another duplicate
of the current bio.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
drivers/md/dm.c | 24 +++++++++++++++++++-----
include/linux/device-mapper.h | 2 ++
2 files changed, 21 insertions(+), 5 deletions(-)
Index: linux-3.14-rc6/drivers/md/dm.c
===================================================================
--- linux-3.14-rc6.orig/drivers/md/dm.c 2014-03-14 23:25:27.000000000 +0100
+++ linux-3.14-rc6/drivers/md/dm.c 2014-03-14 23:33:09.000000000 +0100
@@ -1129,9 +1129,9 @@ EXPORT_SYMBOL_GPL(dm_set_target_max_io_l
* to make it empty)
* The target requires that region 3 is to be sent in the next bio.
*
- * If the target wants to receive multiple copies of the bio with num_write_bios
- * or num_write_same_bios, the partially processed part (the sum of regions 1+2)
- * must be the same for all copies of the bio.
+ * If the target wants to receive multiple copies of the bio with num_*_bios or
+ * dm_ask_for_duplicate_bio, the partially processed part (the sum of regions
+ * 1+2) must be the same for all copies of the bio.
*/
void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors)
{
@@ -1144,6 +1144,17 @@ void dm_accept_partial_bio(struct bio *b
}
EXPORT_SYMBOL_GPL(dm_accept_partial_bio);
+/*
+ * The target driver can call this function only from the map routine. The
+ * target driver requests that the dm sends more duplicates of the current bio.
+ */
+void dm_ask_for_duplicate_bios(struct bio *bio, unsigned n_duplicates)
+{
+ struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
+ (*tio->num_bios) += n_duplicates;
+}
+EXPORT_SYMBOL_GPL(dm_ask_for_duplicate_bios);
+
static void __map_bio(struct dm_target_io *tio)
{
int r;
@@ -1234,12 +1245,14 @@ static struct dm_target_io *alloc_tio(st
static void __clone_and_map_simple_bio(struct clone_info *ci,
struct dm_target *ti,
- unsigned target_bio_nr, unsigned *len)
+ unsigned target_bio_nr, unsigned *len,
+ unsigned *num_bios)
{
struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs, target_bio_nr);
struct bio *clone = &tio->clone;
tio->len_ptr = len;
+ tio->num_bios = num_bios;
/*
* Discard requests require the bio's inline iovecs be initialized.
@@ -1259,7 +1272,7 @@ static void __send_duplicate_bios(struct
unsigned target_bio_nr;
for (target_bio_nr = 0; target_bio_nr < num_bios; target_bio_nr++)
- __clone_and_map_simple_bio(ci, ti, target_bio_nr, len);
+ __clone_and_map_simple_bio(ci, ti, target_bio_nr, len, &num_bios);
}
static int __send_empty_flush(struct clone_info *ci)
@@ -1285,6 +1298,7 @@ static void __clone_and_map_data_bio(str
for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
tio = alloc_tio(ci, ti, 0, target_bio_nr);
tio->len_ptr = len;
+ tio->num_bios = &num_target_bios;
clone_bio(tio, bio, sector, *len);
__map_bio(tio);
}
Index: linux-3.14-rc6/include/linux/device-mapper.h
===================================================================
--- linux-3.14-rc6.orig/include/linux/device-mapper.h 2014-03-14 23:25:27.000000000 +0100
+++ linux-3.14-rc6/include/linux/device-mapper.h 2014-03-14 23:25:27.000000000 +0100
@@ -277,6 +277,7 @@ struct dm_target_io {
struct dm_target *ti;
unsigned target_bio_nr;
unsigned *len_ptr;
+ unsigned *num_bios;
struct bio clone;
};
@@ -388,6 +389,7 @@ struct gendisk *dm_disk(struct mapped_de
int dm_suspended(struct dm_target *ti);
int dm_noflush_suspending(struct dm_target *ti);
void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
+void dm_ask_for_duplicate_bios(struct bio *bio, unsigned n_duplicates);
union map_info *dm_get_rq_mapinfo(struct request *rq);
struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
--
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