Re: [PATCH v4 2/3] block: consolidate blocksize properties consistency checks

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Roman,

On 5/20/20 10:06 AM, Roman Kagan wrote:
> Several block device properties related to blocksize configuration must
> be in certain relationship WRT each other: physical block must be no
> smaller than logical block; min_io_size, opt_io_size, and
> discard_granularity must be a multiple of a logical block.
> 
> To ensure these requirements are met, add corresponding consistency
> checks to blkconf_blocksizes, adjusting its signature to communicate
> possible error to the caller.  Also remove the now redundant consistency
> checks from the specific devices.
> 
> Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>
> ---
> v4: new patch
> 
>   include/hw/block/block.h   |  2 +-
>   hw/block/block.c           | 29 ++++++++++++++++++++++++++++-
>   hw/block/fdc.c             |  5 ++++-
>   hw/block/nvme.c            |  5 ++++-
>   hw/block/virtio-blk.c      |  7 +------
>   hw/ide/qdev.c              |  5 ++++-
>   hw/scsi/scsi-disk.c        | 10 +++-------
>   hw/usb/dev-storage.c       |  5 ++++-
>   tests/qemu-iotests/172.out |  2 +-
>   9 files changed, 50 insertions(+), 20 deletions(-)
> 
> diff --git a/include/hw/block/block.h b/include/hw/block/block.h
> index d7246f3862..784953a237 100644
> --- a/include/hw/block/block.h
> +++ b/include/hw/block/block.h
> @@ -87,7 +87,7 @@ bool blk_check_size_and_read_all(BlockBackend *blk, void *buf, hwaddr size,
>   bool blkconf_geometry(BlockConf *conf, int *trans,
>                         unsigned cyls_max, unsigned heads_max, unsigned secs_max,
>                         Error **errp);
> -void blkconf_blocksizes(BlockConf *conf);
> +bool blkconf_blocksizes(BlockConf *conf, Error **errp);
>   bool blkconf_apply_backend_options(BlockConf *conf, bool readonly,
>                                      bool resizable, Error **errp);
>   
> diff --git a/hw/block/block.c b/hw/block/block.c
> index bf56c7612b..5f8ebff59c 100644
> --- a/hw/block/block.c
> +++ b/hw/block/block.c
> @@ -61,7 +61,7 @@ bool blk_check_size_and_read_all(BlockBackend *blk, void *buf, hwaddr size,
>       return true;
>   }
>   
> -void blkconf_blocksizes(BlockConf *conf)
> +bool blkconf_blocksizes(BlockConf *conf, Error **errp)
>   {
>       BlockBackend *blk = conf->blk;
>       BlockSizes blocksizes;
> @@ -83,6 +83,33 @@ void blkconf_blocksizes(BlockConf *conf)
>               conf->logical_block_size = BDRV_SECTOR_SIZE;
>           }
>       }
> +
> +    if (conf->logical_block_size > conf->physical_block_size) {
> +        error_setg(errp,
> +                   "logical_block_size > physical_block_size not supported");

"not supported" or "invalid"?

> +        return false;
> +    }
> +
> +    if (conf->min_io_size % conf->logical_block_size) {

It seems the block code usually do:

        if (!QEMU_IS_ALIGNED(conf->min_io_size, conf->logical_block_size)) {

> +        error_setg(errp,
> +                   "min_io_size must be a multple of logical_block_size");

Typo "multple" -> "multiple".

> +        return false;
> +    }
> +
> +    if (conf->opt_io_size % conf->logical_block_size) {
> +        error_setg(errp,
> +                   "opt_io_size must be a multple of logical_block_size");

Ditto.

> +        return false;
> +    }
> +
> +    if (conf->discard_granularity != -1 &&
> +        conf->discard_granularity % conf->logical_block_size) {
> +        error_setg(errp, "discard_granularity must be "
> +                   "a multple of logical_block_size");

Again.

> +        return false;
> +    }
> +
> +    return true;

Usually we return true for error, isn't it?

>   }
>   
>   bool blkconf_apply_backend_options(BlockConf *conf, bool readonly,
> diff --git a/hw/block/fdc.c b/hw/block/fdc.c
> index c5fb9d6ece..8eda572ef4 100644
> --- a/hw/block/fdc.c
> +++ b/hw/block/fdc.c
> @@ -554,7 +554,10 @@ static void floppy_drive_realize(DeviceState *qdev, Error **errp)
>           read_only = !blk_bs(dev->conf.blk) || blk_is_read_only(dev->conf.blk);
>       }
>   
> -    blkconf_blocksizes(&dev->conf);
> +    if (!blkconf_blocksizes(&dev->conf, errp)) {
> +        return;
> +    }
> +
>       if (dev->conf.logical_block_size != 512 ||
>           dev->conf.physical_block_size != 512)
>       {
> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> index 2f3100e56c..672650e162 100644
> --- a/hw/block/nvme.c
> +++ b/hw/block/nvme.c
> @@ -1390,7 +1390,10 @@ static void nvme_realize(PCIDevice *pci_dev, Error **errp)
>           host_memory_backend_set_mapped(n->pmrdev, true);
>       }
>   
> -    blkconf_blocksizes(&n->conf);
> +    if (!blkconf_blocksizes(&n->conf, errp)) {
> +        return;
> +    }
> +
>       if (!blkconf_apply_backend_options(&n->conf, blk_is_read_only(n->conf.blk),
>                                          false, errp)) {
>           return;
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 413083e62f..4ffdb130be 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -1162,12 +1162,7 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
>           return;
>       }
>   
> -    blkconf_blocksizes(&conf->conf);
> -
> -    if (conf->conf.logical_block_size >
> -        conf->conf.physical_block_size) {
> -        error_setg(errp,
> -                   "logical_block_size > physical_block_size not supported");

Ah, "not supported" comes from here, OK.

> +    if (!blkconf_blocksizes(&conf->conf, errp)) {
>           return;
>       }
>   
> diff --git a/hw/ide/qdev.c b/hw/ide/qdev.c
> index 06b11583f5..b4821b2403 100644
> --- a/hw/ide/qdev.c
> +++ b/hw/ide/qdev.c
> @@ -187,7 +187,10 @@ static void ide_dev_initfn(IDEDevice *dev, IDEDriveKind kind, Error **errp)
>           return;
>       }
>   
> -    blkconf_blocksizes(&dev->conf);
> +    if (!blkconf_blocksizes(&dev->conf, errp)) {
> +        return;
> +    }
> +
>       if (dev->conf.logical_block_size != 512) {
>           error_setg(errp, "logical_block_size must be 512 for IDE");
>           return;
> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
> index 387503e11b..06c8f1ba92 100644
> --- a/hw/scsi/scsi-disk.c
> +++ b/hw/scsi/scsi-disk.c
> @@ -2346,12 +2346,7 @@ static void scsi_realize(SCSIDevice *dev, Error **errp)
>           return;
>       }
>   
> -    blkconf_blocksizes(&s->qdev.conf);
> -
> -    if (s->qdev.conf.logical_block_size >
> -        s->qdev.conf.physical_block_size) {
> -        error_setg(errp,
> -                   "logical_block_size > physical_block_size not supported");
> +    if (!blkconf_blocksizes(&s->qdev.conf, errp)) {
>           return;
>       }
>   
> @@ -2436,7 +2431,8 @@ static void scsi_hd_realize(SCSIDevice *dev, Error **errp)
>       if (s->qdev.conf.blk) {
>           ctx = blk_get_aio_context(s->qdev.conf.blk);
>           aio_context_acquire(ctx);
> -        blkconf_blocksizes(&s->qdev.conf);
> +        /* ignore errors, blocksizes will be revalidated in scsi_realize */
> +        blkconf_blocksizes(&s->qdev.conf, NULL);

Hmm, why not bail out ASAP on error?

Good cleanup otherwise.

>       }
>       s->qdev.blocksize = s->qdev.conf.logical_block_size;
>       s->qdev.type = TYPE_DISK;
> diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
> index 4eba47538d..de461f37bd 100644
> --- a/hw/usb/dev-storage.c
> +++ b/hw/usb/dev-storage.c
> @@ -599,7 +599,10 @@ static void usb_msd_storage_realize(USBDevice *dev, Error **errp)
>           return;
>       }
>   
> -    blkconf_blocksizes(&s->conf);
> +    if (!blkconf_blocksizes(&s->conf, errp)) {
> +        return;
> +    }
> +
>       if (!blkconf_apply_backend_options(&s->conf, blk_is_read_only(blk), true,
>                                          errp)) {
>           return;
> diff --git a/tests/qemu-iotests/172.out b/tests/qemu-iotests/172.out
> index 7abbe82427..59cc70aebb 100644
> --- a/tests/qemu-iotests/172.out
> +++ b/tests/qemu-iotests/172.out
> @@ -1204,7 +1204,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,physica
>                   drive-type = "144"
>   
>   Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,logical_block_size=4096
> -QEMU_PROG: -device floppy,drive=none0,logical_block_size=4096: Physical and logical block size must be 512 for floppy
> +QEMU_PROG: -device floppy,drive=none0,logical_block_size=4096: logical_block_size > physical_block_size not supported
>   
>   Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,physical_block_size=1024
>   QEMU_PROG: -device floppy,drive=none0,physical_block_size=1024: Physical and logical block size must be 512 for floppy
>