[PATCH 2/3] block/loop: use FALLOC_FL_ZERO_RANGE for REQ_OP_WRITE_ZEROES

[Shaohua Li]

REQ_OP_WRITE_ZEROES really means zero the data. And the in
blkdev_fallocate, FALLOC_FL_ZERO_RANGE will retry but
FALLOC_FL_PUNCH_HOLE not, even loop request doesn't have
BLKDEV_ZERO_NOFALLBACK set.

Signed-off-by: Shaohua Li <s...@fb.com>
---
 drivers/block/loop.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 054dccc..a30aa45 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -430,6 +430,9 @@ static int lo_discard(struct loop_device *lo, struct 
request *rq, loff_t pos)
        int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
        int ret;
 
+       if (req_op(rq) == REQ_OP_WRITE_ZEROES)
+               mode = FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE;
+
        if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) {
                ret = -EOPNOTSUPP;
                goto out;
-- 
2.9.5