block: add support for REQ_OP_WRITE_ZEROES
This adds a new block layer operation to zero out a range of
LBAs. This allows to implement zeroing for devices that don't use
either discard with a predictable zero pattern or WRITE SAME of zeroes.
The prominent example of that is NVMe with the Write Zeroes command,
but in the future, this should also help with improving the way
zeroing discards work. For this operation, suitable entry is exported in
sysfs which indicate the number of maximum bytes allowed in one
write zeroes operation by the device.
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@hgst.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 70a7244..b153239 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -76,7 +76,8 @@ static inline bool bio_has_data(struct bio *bio)
if (bio &&
bio->bi_iter.bi_size &&
bio_op(bio) != REQ_OP_DISCARD &&
- bio_op(bio) != REQ_OP_SECURE_ERASE)
+ bio_op(bio) != REQ_OP_SECURE_ERASE &&
+ bio_op(bio) != REQ_OP_WRITE_ZEROES)
return true;
return false;
@@ -86,7 +87,8 @@ static inline bool bio_no_advance_iter(struct bio *bio)
{
return bio_op(bio) == REQ_OP_DISCARD ||
bio_op(bio) == REQ_OP_SECURE_ERASE ||
- bio_op(bio) == REQ_OP_WRITE_SAME;
+ bio_op(bio) == REQ_OP_WRITE_SAME ||
+ bio_op(bio) == REQ_OP_WRITE_ZEROES;
}
static inline bool bio_mergeable(struct bio *bio)
@@ -188,18 +190,19 @@ static inline unsigned bio_segments(struct bio *bio)
struct bvec_iter iter;
/*
- * We special case discard/write same, because they interpret bi_size
- * differently:
+ * We special case discard/write same/write zeroes, because they
+ * interpret bi_size differently:
*/
- if (bio_op(bio) == REQ_OP_DISCARD)
+ switch (bio_op(bio)) {
+ case REQ_OP_DISCARD:
+ case REQ_OP_SECURE_ERASE:
+ case REQ_OP_WRITE_SAME:
+ case REQ_OP_WRITE_ZEROES:
return 1;
-
- if (bio_op(bio) == REQ_OP_SECURE_ERASE)
- return 1;
-
- if (bio_op(bio) == REQ_OP_WRITE_SAME)
- return 1;
+ default:
+ break;
+ }
bio_for_each_segment(bv, bio, iter)
segs++;