| Message ID | alpine.LRH.2.02.1403141843520.31047@file01.intranet.prod.int.rdu2.redhat.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
On Fri, Mar 14 2014 at 6:44pm -0400, Mikulas Patocka <mpatocka@redhat.com> wrote: > This function can be used if the target needs to receive another duplicate > of the current bio. > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > --- > 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; Hey Mikulas, I'm not immediately seeing how increasing tio->num_bios from within a target's map method, using dm_ask_for_duplicate_bios, will cause DM core to send duplicates. Nothing in DM core actually consumes tio->num_bios -- please advise. Thanks, Mike -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On Fri, 25 Apr 2014, Mike Snitzer wrote: > On Fri, Mar 14 2014 at 6:44pm -0400, > Mikulas Patocka <mpatocka@redhat.com> wrote: > > > This function can be used if the target needs to receive another duplicate > > of the current bio. > > > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > > > --- > > 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; > > Hey Mikulas, > > I'm not immediately seeing how increasing tio->num_bios from within a > target's map method, using dm_ask_for_duplicate_bios, will cause DM core > to send duplicates. > > Nothing in DM core actually consumes tio->num_bios -- please advise. > > Thanks, > Mike tio->num_bios is a pointer. You don't increase tio->num_bios, you increase the value it points to. It points to the local variable that is the limit of the for loop. Mikulas -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On Mon, Apr 28 2014 at 11:09am -0400, Mikulas Patocka <mpatocka@redhat.com> wrote: > > > On Fri, 25 Apr 2014, Mike Snitzer wrote: > > > > Hey Mikulas, > > > > I'm not immediately seeing how increasing tio->num_bios from within a > > target's map method, using dm_ask_for_duplicate_bios, will cause DM core > > to send duplicates. > > > > Nothing in DM core actually consumes tio->num_bios -- please advise. > > > > Thanks, > > Mike > > tio->num_bios is a pointer. You don't increase tio->num_bios, you increase > the value it points to. It points to the local variable that is the limit > of the for loop. I see, thanks for clarifying. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
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);
This function can be used if the target needs to receive another duplicate of the current bio. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> --- drivers/md/dm.c | 24 +++++++++++++++++++----- include/linux/device-mapper.h | 2 ++ 2 files changed, 21 insertions(+), 5 deletions(-) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel