[PATCH V4 16/17] block: ublk_drv: don't check buffer in case of zero copy

Ming Lei
2023-03-24T14:01:05Z

In case of zero copy, ublk server needn't to pre-allocate IO buffer
and provide it to driver more.

Meantime not set the buffer in case of zero copy any more, and the
userspace can use pread()/pwrite() to read from/write to the io request
buffer, which is easier & simpler from userspace viewpoint.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
drivers/block/ublk_drv.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index e6b528750b3c..979444647831 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1405,25 +1405,30 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)
goto out;
/* FETCH_RQ has to provide IO buffer if NEED GET DATA is not enabled */
- if (!ub_cmd->addr && !ublk_need_get_data(ubq))
- goto out;
+ if (!ublk_support_zc(ubq)) {
+ if (!ub_cmd->addr && !ublk_need_get_data(ubq))
+ goto out;
+ io->addr = ub_cmd->addr;
+ }
io->cmd = cmd;
io->flags |= UBLK_IO_FLAG_ACTIVE;
- io->addr = ub_cmd->addr;
-
ublk_mark_io_ready(ub, ubq);
break;
case UBLK_IO_COMMIT_AND_FETCH_REQ:
req = blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag);
+
+ if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
+ goto out;
/*
* COMMIT_AND_FETCH_REQ has to provide IO buffer if NEED GET DATA is
* not enabled or it is Read IO.
*/
- if (!ub_cmd->addr && (!ublk_need_get_data(ubq) || req_op(req) == REQ_OP_READ))
- goto out;
- if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
- goto out;
- io->addr = ub_cmd->addr;
+ if (!ublk_support_zc(ubq)) {
+ if (!ub_cmd->addr && (!ublk_need_get_data(ubq) ||
+ req_op(req) == REQ_OP_READ))
+ goto out;
+ io->addr = ub_cmd->addr;
+ }
io->flags |= UBLK_IO_FLAG_ACTIVE;
io->cmd = cmd;
ublk_commit_completion(ub, ub_cmd);
--
2.39.2