[PATCH 1/4] ublk: factor out ublk_commit_and_fetch

Uday Shankar
2025-04-21T23:46:42Z

Move the logic for the UBLK_IO_COMMIT_AND_FETCH_REQ opcode into its own
function. This also allows us to mark ublk_queue pointers as const for
that operation, which can help prevent data races since we may allow
concurrent operation on one ublk_queue in the future. Also open code
ublk_commit_completion in ublk_commit_and_fetch to reduce the number of
parameters/avoid a redundant lookup.

Suggested-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
---
drivers/block/ublk_drv.c | 91 +++++++++++++++++++++++-------------------------
1 file changed, 43 insertions(+), 48 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 03653bd7a1dfd69f5545a580dbc74de9d850c0ae..57b8625ae64232a750d4f94e76aaf119c28f9450 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1589,30 +1589,6 @@ static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
}

-static void ublk_commit_completion(struct ublk_device *ub,
- const struct ublksrv_io_cmd *ub_cmd)
-{
- u32 qid = ub_cmd->q_id, tag = ub_cmd->tag;
- struct ublk_queue *ubq = ublk_get_queue(ub, qid);
- struct ublk_io *io = &ubq->ios[tag];
- struct request *req;
-
- /* now this cmd slot is owned by nbd driver */
- io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
- io->res = ub_cmd->result;
-
- /* find the io request and complete */
- req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
- if (WARN_ON_ONCE(unlikely(!req)))
- return;
-
- if (req_op(req) == REQ_OP_ZONE_APPEND)
- req->__sector = ub_cmd->zone_append_lba;
-
- if (likely(!blk_should_fake_timeout(req->q)))
- ublk_put_req_ref(ubq, req);
-}
-
static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
struct request *req)
{
@@ -2015,6 +1991,47 @@ static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq,
return ret;
}

+static int ublk_commit_and_fetch(const struct ublk_queue *ubq,
+ struct ublk_io *io, struct io_uring_cmd *cmd,
+ const struct ublksrv_io_cmd *ub_cmd)
+{
+ struct blk_mq_tags *tags = ubq->dev->tag_set.tags[ub_cmd->q_id];
+ struct request *req = blk_mq_tag_to_rq(tags, ub_cmd->tag);
+
+ if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
+ return -EINVAL;
+
+ if (ublk_need_map_io(ubq)) {
+ /*
+ * 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))
+ return -EINVAL;
+ } else if (req_op(req) != REQ_OP_ZONE_APPEND && ub_cmd->addr) {
+ /*
+ * User copy requires addr to be unset when command is
+ * not zone append
+ */
+ return -EINVAL;
+ }
+
+ ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
+
+ /* now this cmd slot is owned by ublk driver */
+ io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
+ io->res = ub_cmd->result;
+
+ if (req_op(req) == REQ_OP_ZONE_APPEND)
+ req->__sector = ub_cmd->zone_append_lba;
+
+ if (likely(!blk_should_fake_timeout(req->q)))
+ ublk_put_req_ref(ubq, req);
+
+ return 0;
+}
+
static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
unsigned int issue_flags,
const struct ublksrv_io_cmd *ub_cmd)
@@ -2025,7 +2042,6 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
u32 cmd_op = cmd->cmd_op;
unsigned tag = ub_cmd->tag;
int ret = -EINVAL;
- struct request *req;

pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n",
__func__, cmd->cmd_op, ub_cmd->q_id, tag,
@@ -2076,30 +2092,9 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
goto out;
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;
-
- if (ublk_need_map_io(ubq)) {
- /*
- * 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;
- } else if (req_op(req) != REQ_OP_ZONE_APPEND && ub_cmd->addr) {
- /*
- * User copy requires addr to be unset when command is
- * not zone append
- */
- ret = -EINVAL;
+ ret = ublk_commit_and_fetch(ubq, io, cmd, ub_cmd);
+ if (ret)
goto out;
- }
-
- ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
- ublk_commit_completion(ub, ub_cmd);
break;
case UBLK_IO_NEED_GET_DATA:
if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))

--
2.34.1