On 5/4/23 13:18, Breno Leitao wrote:
Currently uring CMD operation relies on having large SQEs, but future
operations might want to use normal SQE.
The io_uring_cmd currently only saves the payload (cmd) part of the SQE,
but, for commands that use normal SQE size, it might be necessary to
access the initial SQE fields outside of the payload/cmd block. So,
saves the whole SQE other than just the pdu.
This changes slightly how the io_uring_cmd works, since the cmd
structures and callbacks are not opaque to io_uring anymore. I.e, the
callbacks can look at the SQE entries, not only, in the cmd structure.
The main advantage is that we don't need to create custom structures for
simple commands.
Creates io_uring_sqe_cmd() that returns the cmd private data as a null
pointer and avoids casting in the callee side.
Also, make most of ublk_drv's sqe->cmd priv structure into const, and use
io_uring_sqe_cmd() to get the private structure, removing the unwanted
cast. (There is one case where the cast is still needed since the
header->{len,addr} is updated in the private structure)
Suggested-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
Reviewed-by: Keith Busch <kbusch@xxxxxxxxxx>
---
drivers/block/ublk_drv.c | 26 +++++++++++++-------------
drivers/nvme/host/ioctl.c | 2 +-
include/linux/io_uring.h | 7 ++++++-
io_uring/opdef.c | 2 +-
io_uring/uring_cmd.c | 9 +++------
5 files changed, 24 insertions(+), 22 deletions(-)
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index c73cc57ec547..42f4d7ca962e 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
[...]
@@ -2025,7 +2025,7 @@ static int ublk_ctrl_start_recovery(struct ublk_device *ub,
static int ublk_ctrl_end_recovery(struct ublk_device *ub,
struct io_uring_cmd *cmd)
{
- struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
+ const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
int ublksrv_pid = (int)header->data[0];
int ret = -EINVAL;
@@ -2092,7 +2092,7 @@ static int ublk_char_dev_permission(struct ublk_device *ub,
static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub,
struct io_uring_cmd *cmd)
{
- struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
+ struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)io_uring_sqe_cmd(cmd->sqe);
Seems it's here to cast out const. Not an issue as apparently ctrl
goes to io-wq and so copies sqes, and it's definitely not a problem
of this patch, but seems fragile.
bool unprivileged = ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV;
void __user *argp = (void __user *)(unsigned long)header->addr;
char *dev_path = NULL;
@@ -2171,7 +2171,7 @@ static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub,
static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
unsigned int issue_flags)
{
- struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
+ const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
struct ublk_device *ub = NULL;
int ret = -EINVAL;
[...]
--
Pavel Begunkov
