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ublk: Add UBLK_U_CMD_UPDATE_SIZE 

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.

Signed-off-by: Omri Mann <omri@nvidia.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/2a370ab1-d85b-409d-b762-f9f3f6bdf705@nvidia.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Omri Mann 2025-04-21 13:59:50 +03:00 committed by Jens Axboe
parent 033b667a82
commit 98b995660b
2 changed files with 26 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
drivers/block/ublk_drv.c
View File

@ -50,6 +50,7 @@
/* private ioctl command mirror */
#define UBLK_CMD_DEL_DEV_ASYNC _IOC_NR(UBLK_U_CMD_DEL_DEV_ASYNC)
#define UBLK_CMD_UPDATE_SIZE _IOC_NR(UBLK_U_CMD_UPDATE_SIZE)
#define UBLK_IO_REGISTER_IO_BUF _IOC_NR(UBLK_U_IO_REGISTER_IO_BUF)
#define UBLK_IO_UNREGISTER_IO_BUF _IOC_NR(UBLK_U_IO_UNREGISTER_IO_BUF)
@ -64,7 +65,8 @@
| 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 \
@ -3075,6 +3077,16 @@ static int ublk_ctrl_get_features(const struct ublksrv_ctrl_cmd *header)
return 0;
}
static void ublk_ctrl_set_size(struct ublk_device *ub, const struct ublksrv_ctrl_cmd *header)
{
struct ublk_param_basic *p = &ub->params.basic;
u64 new_size = 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
@ -3160,6 +3172,7 @@ 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 UBLK_CMD_UPDATE_SIZE:
mask = MAY_READ | MAY_WRITE;
break;
default:
@ -3251,6 +3264,10 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
case UBLK_CMD_END_USER_RECOVERY:
ret = ublk_ctrl_end_recovery(ub, header);
break;
case UBLK_CMD_UPDATE_SIZE:
ublk_ctrl_set_size(ub, header);
ret = 0;
break;
default:
ret = -EOPNOTSUPP;
break;

8
include/uapi/linux/ublk_cmd.h
View File

@ -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 +213,12 @@
*/
#define UBLK_F_USER_RECOVERY_FAIL_IO (1ULL << 9)
/*
* Resizing a block device is possible with UBLK_U_CMD_UPDATE_SIZE
* New size is passed in cmd->data[0] and is in units of sectors
*/
#define UBLK_F_UPDATE_SIZE (1ULL << 10)
/* device state */
#define UBLK_S_DEV_DEAD 0
#define UBLK_S_DEV_LIVE 1