[PATCH 17/17] md: raid10: avoid direct access to bvec table in handle_reshape_read_error

Ming Lei
2017-02-16T11:47:32Z

The cost is 128bytes(8*16) stack space in kernel thread context, and
just use the bio helper to retrieve pages from bio.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
drivers/md/raid10.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 5016ce8163c3..d9d7c79a3bd4 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -4689,7 +4689,15 @@ static int handle_reshape_read_error(struct mddev *mddev,
struct r10bio *r10b = &on_stack.r10_bio;
int slot = 0;
int idx = 0;
- struct bio_vec *bvec = r10_bio->master_bio->bi_io_vec;
+ struct bio_vec *bvl;
+ struct page *pages[RESYNC_PAGES];
+
+ /*
+ * This bio is allocated in reshape_request(), and size
+ * is still RESYNC_PAGES
+ */
+ bio_for_each_segment_all(bvl, r10_bio->master_bio, idx)
+ pages[idx] = bvl->bv_page;

r10b->sector = r10_bio->sector;
__raid10_find_phys(&conf->prev, r10b);
@@ -4718,7 +4726,7 @@ static int handle_reshape_read_error(struct mddev *mddev,
success = sync_page_io(rdev,
addr,
s << 9,
- bvec[idx].bv_page,
+ pages[idx],
REQ_OP_READ, 0, false);
rdev_dec_pending(rdev, mddev);
rcu_read_lock();
--
2.7.4