Hello Jared, On Thu, Apr 03, 2025 at 12:37:11PM +0000, Jared Holzman wrote: > Apologies if this is a dup, but I am not seeing the original mail on the mailing list archive. I guess it is because the patch is sent as html, instead of plain test, please follow the patch submission guide: https://www.kernel.org/doc/Documentation/process/submitting-patches.rst > > ________________________________ > From: Jared Holzman <jholzman@xxxxxxxxxx> > Sent: Monday, 31 March 2025 4:54 PM > To: linux-block@xxxxxxxxxxxxxxx <linux-block@xxxxxxxxxxxxxxx> > Cc: ming.lei@xxxxxxxxxx <ming.lei@xxxxxxxxxx>; Omri Mann <omri@xxxxxxxxxx>; Ofer Oshri <ofer@xxxxxxxxxx>; Omri Levi <omril@xxxxxxxxxx>; Jared Holzman <jholzman@xxxxxxxxxx> > Subject: [PATCH] ublk: Add UBLK_U_CMD_SET_SIZE > > From: Omri Mann <omri@xxxxxxxxxx> > > 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. The requirement is reasonable. > > This patch adds a new ublk command UBLK_U_CMD_SET_SIZE to allow the > ublk block device to be resized on-the-fly. Looks CMD_SET_SIZE is not generic enough, maybe UBLK_CMD_UPDATE_PARAMS can be added for support any parameter update by allowing to do it when device is in LIVE state. > > Signed-off-by: Omri Mann <omri@xxxxxxxxxx> > --- > Documentation/block/ublk.rst | 5 +++++ > drivers/block/ublk_drv.c | 26 +++++++++++++++++++++++++- > include/uapi/linux/ublk_cmd.h | 7 +++++++ > 3 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/Documentation/block/ublk.rst b/Documentation/block/ublk.rst > index 1e0e7358e14a..7eca87a66b9c 100644 > --- a/Documentation/block/ublk.rst > +++ b/Documentation/block/ublk.rst > @@ -139,6 +139,11 @@ managing and controlling ublk devices with help of several control commands: > set up the per-queue context efficiently, such as bind affine CPUs with IO > pthread and try to allocate buffers in IO thread context. > > +- ``UBLK_F_SET_SIZE`` > + > + Allows changing the size of the block device after it has started. Useful for > + userspace implementations that allow extending the underlying block device. > + > - ``UBLK_CMD_GET_DEV_INFO`` > > For retrieving device info via ``ublksrv_ctrl_dev_info``. It is the server's > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c > index c060da409ed8..ab6364475b9c 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_SET_SIZE) > > #define UBLK_F_ALL_RECOVERY_FLAGS (UBLK_F_USER_RECOVERY \ > | UBLK_F_USER_RECOVERY_REISSUE \ > @@ -2917,6 +2918,25 @@ static int ublk_ctrl_get_features(struct io_uring_cmd *cmd) > return 0; > } > > +static int 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]; > + int ret = 0; > + unsigned int memflags; > + > + p->dev_sectors = new_size; > + > + memflags = blk_mq_freeze_queue(ub->ub_disk->queue); > + mutex_lock(&ub->mutex); > + set_capacity_and_notify(ub->ub_disk, p->dev_sectors); > + mutex_unlock(&ub->mutex); > + blk_mq_unfreeze_queue(ub->ub_disk->queue, memflags); Actually if it is just for updating device size, queue freeze isn't needed, because bio_check_eod() is called without grabbing ->q_usage_counter, but for updating other parameters, freezing queue is often needed. Thanks, Ming
