From: Yu Kuai <yukuai3@xxxxxxxxxx>
Currently brd_do_discard() will just skip unaligned sectors, and in this
case user will still get old data after discard. Fix this by writing
zero data to unaligned sectors.
Fixes: 9ead7efc6f3f ("brd: implement discard support")
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
drivers/block/brd.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index bf1e1b2a0d28..b5908703fb4b 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -224,6 +224,21 @@ static int brd_do_bvec(struct brd_device *brd, struct page *page,
return err;
}
+static void brd_zero_range(struct brd_device *brd, sector_t sector, u32 size)
+{
+ unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
+ struct page *page;
+ void *dst;
+
+ page = brd_lookup_page(brd, sector);
+ if (!page)
+ return;
+
+ dst = kmap_local_page(page);
+ memset(dst + offset, 0, size);
+ kunmap_local(dst);
+}
+
static void brd_free_one_page(struct rcu_head *head)
{
struct page *page = container_of(head, struct page, rcu_head);
@@ -234,10 +249,17 @@ static void brd_free_one_page(struct rcu_head *head)
static void brd_do_discard(struct brd_device *brd, sector_t sector, u32 size)
{
sector_t aligned_sector = round_up(sector, PAGE_SECTORS);
- sector_t aligned_end = round_down(sector + (size >> SECTOR_SHIFT),
- PAGE_SECTORS);
+ sector_t sector_end = sector + (size >> SECTOR_SHIFT);
+ sector_t aligned_end = round_down(sector_end, PAGE_SECTORS);
struct page *page;
+ if (aligned_sector > sector)
+ brd_zero_range(brd, sector,
+ (aligned_sector - sector) << SECTOR_SHIFT);
+ if (aligned_end < sector_end)
+ brd_zero_range(brd, aligned_end,
+ (sector_end - aligned_end) << SECTOR_SHIFT);
+
if (aligned_end <= aligned_sector)
return;
--
2.39.2
