block: ublk: check IO buffer based on flag need_get_data

Currently, uring_cmd with UBLK_IO_FETCH_REQ or
UBLK_IO_COMMIT_AND_FETCH_REQ is always checked whether
userspace server has provided IO buffer even flag
UBLK_F_NEED_GET_DATA is configured.

This is a excessive check. If UBLK_F_NEED_GET_DATA is
configured, FETCH_RQ doesn't need to provide IO buffer;
COMMIT_AND_FETCH_REQ also doesn't need to do that if
the IO type is not READ.

Check ub_cmd->addr together with ublk_need_get_data()
and IO type in ublk_ch_uring_cmd().

With this fix, userspace server doesn't need to preserve
buffers for every ublk_io when flag UBLK_F_NEED_GET_DATA
is configured, in order to save memory.

Signed-off-by: Liu Xiaodong <xiaodong.liu@intel.com>
Fixes: c86019ff75c1 ("ublk_drv: add support for UBLK_IO_NEED_GET_DATA")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230210141356.112321-1-xiaodong.liu@intel.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index e6eceee..f48d213 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1265,6 +1265,7 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
        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,
@@ -1315,8 +1316,8 @@ 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 (!ub_cmd->addr)
+               /* 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;
                io->cmd = cmd;
                io->flags |= UBLK_IO_FLAG_ACTIVE;
@@ -1325,8 +1326,12 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
                ublk_mark_io_ready(ub, ubq);
                break;
        case UBLK_IO_COMMIT_AND_FETCH_REQ:
-               /* FETCH_RQ has to provide IO buffer */
-               if (!ub_cmd->addr)
+               req = blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag);
+               /*
+                * 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;