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Subjectdm: shrink data blocks using bitmap for hash reading
Date
From: xianrong_zhou <xianrong_zhou@163.com>

If check_at_most_once enabled, just like verity work,
the prefetching work should check for data block bitmap
firstly before reading hash block as well.This can reduce
99.28% data blocks which need not to read hash blocks.

The reduced data blocks would be enlarged again by cluster
reading later.

Signed-off-by: xianrong_zhou <xianrong_zhou@163.com>
Signed-off-by: yuanjiong.gao <yuanjiong.gao@transsion.com>
Signed-off-by: ruxian.feng <ruxian.feng@transsion.com>
---
drivers/md/dm-verity-target.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index 4fb33e7562c5..fe4c15a0723c 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -581,6 +581,23 @@ static void verity_prefetch_io(struct work_struct *work)
struct dm_verity *v = pw->v;
int i;

+ if (v->validated_blocks) {
+ while (pw->n_blocks) {
+ if (unlikely(!test_bit(pw->block, v->validated_blocks)))
+ break;
+ pw->block++;
+ pw->n_blocks--;
+ }
+ while (pw->n_blocks) {
+ if (unlikely(!test_bit(pw->block + pw->n_blocks - 1,
+ v->validated_blocks)))
+ break;
+ pw->n_blocks--;
+ }
+ if (!pw->n_blocks)
+ return;
+ }
+
for (i = v->levels - 2; i >= 0; i--) {
sector_t hash_block_start;
sector_t hash_block_end;
--
2.17.2

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