From: Junichi Nomura <j-nomura@xxxxxxxxxxxxx>
alloc_tio() uses bio_alloc_bioset() to allocate a clone-bio for a bio.
alloc_tio() takes the number of bvecs to allocate for the clone-bio.
However, with v3.14's immutable biovec changes DM now uses
__bio_clone_fast() and no longer needs to allocate bvecs.
In practice, the 'nr_iovecs' passed to alloc_tio() is always effectively
0. __clone_and_map_simple_bio() looked like it was passing non-zero
nr_iovecs, but its value was always within the range of inline bvecs and
no allocation actually happened. If allocation happened, the BUG_ON() in
__bio_clone_fast() would've triggered.
Remove the nr_iovecs parameter from alloc_tio() to prevent possible
future bio_alloc_bioset() mis-use of a new bioset interface that will no
longer allow bvecs to be allocated.
Also fix extra whitespace before the __bio_clone_fast() call in
__clone_and_map_simple_bio().
Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/md/dm.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index e1db62c..aaeed99 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1372,13 +1372,13 @@ static void clone_bio(struct dm_target_io *tio, struct bio *bio,
}
static struct dm_target_io *alloc_tio(struct clone_info *ci,
- struct dm_target *ti, int nr_iovecs,
+ struct dm_target *ti,
unsigned target_bio_nr)
{
struct dm_target_io *tio;
struct bio *clone;
- clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, ci->md->bs);
+ clone = bio_alloc_bioset(GFP_NOIO, 0, ci->md->bs);
tio = container_of(clone, struct dm_target_io, clone);
tio->io = ci->io;
@@ -1392,17 +1392,12 @@ static void __clone_and_map_simple_bio(struct clone_info *ci,
struct dm_target *ti,
unsigned target_bio_nr, unsigned *len)
{
- struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs, target_bio_nr);
+ struct dm_target_io *tio = alloc_tio(ci, ti, target_bio_nr);
struct bio *clone = &tio->clone;
tio->len_ptr = len;
- /*
- * Discard requests require the bio's inline iovecs be initialized.
- * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush
- * and discard, so no need for concern about wasted bvec allocations.
- */
- __bio_clone_fast(clone, ci->bio);
+ __bio_clone_fast(clone, ci->bio);
if (len)
bio_setup_sector(clone, ci->sector, *len);
@@ -1445,7 +1440,7 @@ static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti
num_target_bios = ti->num_write_bios(ti, bio);
for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
- tio = alloc_tio(ci, ti, 0, target_bio_nr);
+ tio = alloc_tio(ci, ti, target_bio_nr);
tio->len_ptr = len;
clone_bio(tio, bio, sector, *len);
__map_bio(tio);
--
1.9.3
--
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