diff mbox series

[v3] : ublk: Add UBLK_U_CMD_UPDATE_SIZE

Message ID 36ba7ff3-ff0e-4db1-acb1-8e7a60a427cc@nvidia.com (mailing list archive)
State New
Headers show
Series [v3] : ublk: Add UBLK_U_CMD_UPDATE_SIZE | expand

Commit Message

Jared Holzman April 14, 2025, 11:44 a.m. UTC 
Currently ublk only allows the size of the ublkb block device to be
set via UBLK_CMD_SET_PARAMS before UBLK_CMD_START_DEV is triggered.

This does not provide support for extendable user-space block devices
without having to stop and restart the underlying ublkb block device
causing IO interruption.

This patch adds a new ublk command UBLK_U_CMD_UPDATE_SIZE to allow the
ublk block device to be resized on-the-fly.

Feature flag UBLK_F_UPDATE_SIZE is also added to indicate support for 
this command.

Signed-off-by: Omri Mann <omri@nvidia.com>
---
  drivers/block/ublk_drv.c      | 19 ++++++++++++++++++-
  include/uapi/linux/ublk_cmd.h |  7 +++++++
  2 files changed, 25 insertions(+), 1 deletion(-)

Comments

Caleb Sander Mateos April 14, 2025, 3:54 p.m. UTC | #1 
On Mon, Apr 14, 2025 at 4:45 AM Jared Holzman <jholzman@nvidia.com> wrote:
>
> Currently ublk only allows the size of the ublkb block device to be
> set via UBLK_CMD_SET_PARAMS before UBLK_CMD_START_DEV is triggered.
>
> This does not provide support for extendable user-space block devices
> without having to stop and restart the underlying ublkb block device
> causing IO interruption.
>
> This patch adds a new ublk command UBLK_U_CMD_UPDATE_SIZE to allow the
> ublk block device to be resized on-the-fly.
>
> Feature flag UBLK_F_UPDATE_SIZE is also added to indicate support for
> this command.
>
> Signed-off-by: Omri Mann <omri@nvidia.com>
> ---
>   drivers/block/ublk_drv.c      | 19 ++++++++++++++++++-
>   include/uapi/linux/ublk_cmd.h |  7 +++++++
>   2 files changed, 25 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 2fd05c1bd30b..2a8d8b864ef9 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -64,7 +64,8 @@
>                  | UBLK_F_CMD_IOCTL_ENCODE \
>                  | UBLK_F_USER_COPY \
>                  | UBLK_F_ZONED \
> -               | UBLK_F_USER_RECOVERY_FAIL_IO)
> +               | UBLK_F_USER_RECOVERY_FAIL_IO \
> +               | UBLK_F_UPDATE_SIZE)
>
>   #define UBLK_F_ALL_RECOVERY_FLAGS (UBLK_F_USER_RECOVERY \
>                  | UBLK_F_USER_RECOVERY_REISSUE \
> @@ -3052,6 +3053,17 @@ static int ublk_ctrl_get_features(struct
> io_uring_cmd *cmd)
>          return 0;
>   }
>
> +static void ublk_ctrl_set_size(struct ublk_device *ub, struct
> io_uring_cmd *cmd)
> +{
> +       const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);

Can you pass header instead of cmd to this function? See my recent
commit changing most of the other ublk_ctrl handlers:
https://git.kernel.dk/cgit/linux/commit/?h=block-6.15&id=843c6cec1af85f05971b7baf3704801895e77d76

> +       struct ublk_param_basic *p = &ub->params.basic;
> +       size_t new_size = (int)header->data[0];

Why cast from u64 to int and back to size_t?

> +
> +       mutex_lock(&ub->mutex);
> +       p->dev_sectors = new_size;
> +       set_capacity_and_notify(ub->ub_disk, p->dev_sectors);
> +       mutex_unlock(&ub->mutex);
> +}
>   /*
>    * All control commands are sent via /dev/ublk-control, so we have to
> check
>    * the destination device's permission
> @@ -3137,6 +3149,7 @@ static int ublk_ctrl_uring_cmd_permission(struct
> ublk_device *ub,
>          case UBLK_CMD_SET_PARAMS:
>          case UBLK_CMD_START_USER_RECOVERY:
>          case UBLK_CMD_END_USER_RECOVERY:
> +       case _IOC_NR(UBLK_U_CMD_UPDATE_SIZE):
>                  mask = MAY_READ | MAY_WRITE;
>                  break;
>          default:
> @@ -3228,6 +3241,10 @@ static int ublk_ctrl_uring_cmd(struct
> io_uring_cmd *cmd,
>          case UBLK_CMD_END_USER_RECOVERY:
>                  ret = ublk_ctrl_end_recovery(ub, cmd);
>                  break;
> +       case _IOC_NR(UBLK_U_CMD_UPDATE_SIZE):
> +               ublk_ctrl_set_size(ub, cmd);
> +               ret = 0;
> +               break;
>          default:
>                  ret = -EOPNOTSUPP;
>                  break;
> diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
> index 583b86681c93..0e40e497c28f 100644
> --- a/include/uapi/linux/ublk_cmd.h
> +++ b/include/uapi/linux/ublk_cmd.h
> @@ -51,6 +51,8 @@
>          _IOR('u', 0x13, struct ublksrv_ctrl_cmd)
>   #define UBLK_U_CMD_DEL_DEV_ASYNC       \
>          _IOR('u', 0x14, struct ublksrv_ctrl_cmd)
> +#define UBLK_U_CMD_UPDATE_SIZE         \
> +       _IOWR('u', 0x15, struct ublksrv_ctrl_cmd)
>
>   /*
>    * 64bits are enough now, and it should be easy to extend in case of
> @@ -211,6 +213,11 @@
>    */
>   #define UBLK_F_USER_RECOVERY_FAIL_IO (1ULL << 9)
>
> +/*
> + * Resisizing a block device is possible with UBLK_U_CMD_UPDATE_SIZE

"Resisizing" -> "Resizing"?

Best,
Caleb

> + */
> +#define UBLK_F_UPDATE_SIZE              (1ULL << 10)
> +
>   /* device state */
>   #define UBLK_S_DEV_DEAD        0
>   #define UBLK_S_DEV_LIVE        1
> --
> 2.43.0
>
>
diff mbox series

Patch

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 2fd05c1bd30b..2a8d8b864ef9 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -64,7 +64,8 @@ 
                 | UBLK_F_CMD_IOCTL_ENCODE \
                 | UBLK_F_USER_COPY \
                 | UBLK_F_ZONED \
-               | UBLK_F_USER_RECOVERY_FAIL_IO)
+               | UBLK_F_USER_RECOVERY_FAIL_IO \
+               | UBLK_F_UPDATE_SIZE)

  #define UBLK_F_ALL_RECOVERY_FLAGS (UBLK_F_USER_RECOVERY \
                 | UBLK_F_USER_RECOVERY_REISSUE \
@@ -3052,6 +3053,17 @@  static int ublk_ctrl_get_features(struct 
io_uring_cmd *cmd)
         return 0;
  }

+static void ublk_ctrl_set_size(struct ublk_device *ub, struct 
io_uring_cmd *cmd)
+{
+       const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
+       struct ublk_param_basic *p = &ub->params.basic;
+       size_t new_size = (int)header->data[0];
+
+       mutex_lock(&ub->mutex);
+       p->dev_sectors = new_size;
+       set_capacity_and_notify(ub->ub_disk, p->dev_sectors);
+       mutex_unlock(&ub->mutex);
+}
  /*
   * All control commands are sent via /dev/ublk-control, so we have to 
check
   * the destination device's permission
@@ -3137,6 +3149,7 @@  static int ublk_ctrl_uring_cmd_permission(struct 
ublk_device *ub,
         case UBLK_CMD_SET_PARAMS:
         case UBLK_CMD_START_USER_RECOVERY:
         case UBLK_CMD_END_USER_RECOVERY:
+       case _IOC_NR(UBLK_U_CMD_UPDATE_SIZE):
                 mask = MAY_READ | MAY_WRITE;
                 break;
         default:
@@ -3228,6 +3241,10 @@  static int ublk_ctrl_uring_cmd(struct 
io_uring_cmd *cmd,
         case UBLK_CMD_END_USER_RECOVERY:
                 ret = ublk_ctrl_end_recovery(ub, cmd);
                 break;
+       case _IOC_NR(UBLK_U_CMD_UPDATE_SIZE):
+               ublk_ctrl_set_size(ub, cmd);
+               ret = 0;
+               break;
         default:
                 ret = -EOPNOTSUPP;
                 break;
diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
index 583b86681c93..0e40e497c28f 100644
--- a/include/uapi/linux/ublk_cmd.h
+++ b/include/uapi/linux/ublk_cmd.h
@@ -51,6 +51,8 @@ 
         _IOR('u', 0x13, struct ublksrv_ctrl_cmd)
  #define UBLK_U_CMD_DEL_DEV_ASYNC       \
         _IOR('u', 0x14, struct ublksrv_ctrl_cmd)
+#define UBLK_U_CMD_UPDATE_SIZE         \
+       _IOWR('u', 0x15, struct ublksrv_ctrl_cmd)

  /*
   * 64bits are enough now, and it should be easy to extend in case of
@@ -211,6 +213,11 @@ 
   */
  #define UBLK_F_USER_RECOVERY_FAIL_IO (1ULL << 9)

+/*
+ * Resisizing a block device is possible with UBLK_U_CMD_UPDATE_SIZE
+ */
+#define UBLK_F_UPDATE_SIZE              (1ULL << 10)
+
  /* device state */
  #define UBLK_S_DEV_DEAD        0
  #define UBLK_S_DEV_LIVE        1