adam.manzanares@xxxxxxx writes:
> From: Adam Manzanares <adam.manzanares@xxxxxxx>
>
> This is the per-I/O equivalent of the ioprio_set system call.
>
> When IOCB_FLAG_IOPRIO is set on the iocb aio_flags field, then we set the
> newly added kiocb ki_ioprio field to the value in the iocb aio_reqprio field.
>
> We set the blkdev bio iopriority unconditionally, so we need to guarantee the
> kiocb is initialized properly. Added changes to the loopback driver and
> init_sync_kiocb to achieve this.
>
> This patch depends on block: add ioprio_check_cap function.
>
> Signed-off-by: Adam Manzanares <adam.manzanares@xxxxxxx>
Reviewed-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
> ---
> drivers/block/loop.c | 3 +++
> fs/aio.c | 16 ++++++++++++++++
> include/linux/fs.h | 3 +++
> include/uapi/linux/aio_abi.h | 1 +
> 4 files changed, 23 insertions(+)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 5d4e31655d96..dd98dfd97f5e 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -76,6 +76,8 @@
> #include <linux/miscdevice.h>
> #include <linux/falloc.h>
> #include <linux/uio.h>
> +#include <linux/ioprio.h>
> +
> #include "loop.h"
>
> #include <linux/uaccess.h>
> @@ -559,6 +561,7 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
> cmd->iocb.ki_filp = file;
> cmd->iocb.ki_complete = lo_rw_aio_complete;
> cmd->iocb.ki_flags = IOCB_DIRECT;
> + cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
> if (cmd->css)
> kthread_associate_blkcg(cmd->css);
>
> diff --git a/fs/aio.c b/fs/aio.c
> index f3eae5d5771b..44b4572be524 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1451,6 +1451,22 @@ static int aio_prep_rw(struct kiocb *req, struct iocb *iocb)
> if (iocb->aio_flags & IOCB_FLAG_RESFD)
> req->ki_flags |= IOCB_EVENTFD;
> req->ki_hint = file_write_hint(req->ki_filp);
> + if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
> + /*
> + * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
> + * aio_reqprio is interpreted as an I/O scheduling
> + * class and priority.
> + */
> + ret = ioprio_check_cap(iocb->aio_reqprio);
> + if (ret) {
> + pr_debug("aio ioprio check cap error\n");
> + return -EINVAL;
> + }
> +
> + req->ki_ioprio = iocb->aio_reqprio;
> + } else
> + req->ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
> +
> ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
> if (unlikely(ret))
> fput(req->ki_filp);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 50de40dbbb85..73b749ed3ea1 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -36,6 +36,7 @@
> #include <linux/delayed_call.h>
> #include <linux/uuid.h>
> #include <linux/errseq.h>
> +#include <linux/ioprio.h>
>
> #include <asm/byteorder.h>
> #include <uapi/linux/fs.h>
> @@ -302,6 +303,7 @@ struct kiocb {
> void *private;
> int ki_flags;
> u16 ki_hint;
> + u16 ki_ioprio; /* See linux/ioprio.h */
> } __randomize_layout;
>
> static inline bool is_sync_kiocb(struct kiocb *kiocb)
> @@ -1942,6 +1944,7 @@ static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
> .ki_filp = filp,
> .ki_flags = iocb_flags(filp),
> .ki_hint = ki_hint_validate(file_write_hint(filp)),
> + .ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0),
> };
> }
>
> diff --git a/include/uapi/linux/aio_abi.h b/include/uapi/linux/aio_abi.h
> index 2c0a3415beee..d4e768d55d14 100644
> --- a/include/uapi/linux/aio_abi.h
> +++ b/include/uapi/linux/aio_abi.h
> @@ -55,6 +55,7 @@ enum {
> * is valid.
> */
> #define IOCB_FLAG_RESFD (1 << 0)
> +#define IOCB_FLAG_IOPRIO (1 << 1)
>
> /* read() from /dev/aio returns these structures. */
> struct io_event {
