[Devel] [PATCH RH9] dm-ploop: Fix usage of bio_vec on stack

[Kirill Tkhai]

Previously, writing BAT page was synchronous, so
we could use on-stack bio_vec for that.
But after it became asynchronous, we can't do that.
Strange, this has not fired earlier.

https://jira.sw.ru/browse/PSBM-135137
Fixes: bfc5eaaba897 "ploop: Async md writeback"
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 drivers/md/dm-ploop-map.c |   12 ++++++------
 drivers/md/dm-ploop.h     |    1 +
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 4cadf6e45b4d..a558445a1bec 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -1595,17 +1595,17 @@ void ploop_index_wb_submit(struct ploop *ploop, struct ploop_index_wb *piwb)
 {
 	loff_t pos = (loff_t)piwb->page_id << PAGE_SHIFT;
 	struct pio *pio = piwb->pio;
-	struct bio_vec bvec = {
-		.bv_page = piwb->bat_page,
-		.bv_len = PAGE_SIZE,
-		.bv_offset = 0,
-	};
+	struct bio_vec *bvec = &piwb->aux_bvec;
+
+	bvec->bv_page = piwb->bat_page;
+	bvec->bv_len = PAGE_SIZE;
+	bvec->bv_offset = 0;
 
 	pio->bi_iter.bi_sector = to_sector(pos);
 	pio->bi_iter.bi_size = PAGE_SIZE;
 	pio->bi_iter.bi_idx = 0;
 	pio->bi_iter.bi_bvec_done = 0;
-	pio->bi_io_vec = &bvec;
+	pio->bi_io_vec = bvec;
 	pio->level = top_level(ploop);
 	pio->endio_cb = md_write_endio;
 	pio->endio_cb_data = piwb;
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index a7ca942c4670..0a4c6b78e20e 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -106,6 +106,7 @@ struct ploop_index_wb {
 	bool completed;
 	blk_status_t bi_status;
 	u32 page_id;
+	struct bio_vec aux_bvec;
 };
 
 /* Metadata page */