rq->bio can be NULL sometimes, such as flush request, so don't
read bio->bi_seg_front_size until this 'bio' is checked as valid.
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Reported-by: Bart Van Assche <bvanassche@xxxxxxx>
Fixes: dcebd755926b0f39dd1e ("block: use bio_for_each_bvec() to compute multi-page bvec count")
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/blk-merge.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index bed065904677..066b66430523 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -363,13 +363,15 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
struct bio_vec bv, bvprv = { NULL };
int prev = 0;
unsigned int seg_size, nr_phys_segs;
- unsigned front_seg_size = bio->bi_seg_front_size;
+ unsigned front_seg_size;
struct bio *fbio, *bbio;
struct bvec_iter iter;
if (!bio)
return 0;
+ front_seg_size = bio->bi_seg_front_size;
+
switch (bio_op(bio)) {
case REQ_OP_DISCARD:
case REQ_OP_SECURE_ERASE:
--
2.9.5
