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

[Roman Kagan <rvkagan@yandex-team.ru>]

On Wed, May 20, 2020 at 10:57:00AM +0200, Philippe Mathieu-Daudé wrote:
> 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?

I just followed the convention of all other functions with error
handling in this file.

> >   }
> >   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.

Indeed :)

> 
> > +    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?

You're probably right, it'll be cleaner this way.

Thanks,
Roman.

> 
> 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
> > 
>