Re: [RFC 07/22] dm: blk: add UCLASS_PARTITION

Simon Glass
2021-10-11T14:55:45Z

Hi Takahiro,

On Sun, 10 Oct 2021 at 20:29, AKASHI Takahiro
<takahiro.akashi@linaro.org> wrote:
>
> Heinrich,
>
> On Fri, Oct 08, 2021 at 10:23:52AM +0200, Heinrich Schuchardt wrote:
> >
> >
> > On 10/8/21 02:51, AKASHI Takahiro wrote:
> > > On Mon, Oct 04, 2021 at 12:27:59PM +0900, AKASHI Takahiro wrote:
> > > > On Fri, Oct 01, 2021 at 11:30:37AM +0200, Heinrich Schuchardt wrote:
> > > > >
> > > > >
> > > > > On 10/1/21 07:01, AKASHI Takahiro wrote:
> > > > > > UCLASS_PARTITION device will be created as a child node of
> > > > > > UCLASS_BLK device.
> > > > > >
> > > > > > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > > > > > ---
> > > > > > drivers/block/blk-uclass.c | 111 +++++++++++++++++++++++++++++++++++++
> > > > > > include/blk.h | 9 +++
> > > > > > include/dm/uclass-id.h | 1 +
> > > > > > 3 files changed, 121 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/block/blk-uclass.c b/drivers/block/blk-uclass.c
> > > > > > index 83682dcc181a..dd7f3c0fe31e 100644
> > > > > > --- a/drivers/block/blk-uclass.c
> > > > > > +++ b/drivers/block/blk-uclass.c
> > > > > > @@ -12,6 +12,7 @@
> > > > > > #include <log.h>
> > > > > > #include <malloc.h>
> > > > > > #include <part.h>
> > > > > > +#include <string.h>
> > > > > > #include <dm/device-internal.h>
> > > > > > #include <dm/lists.h>
> > > > > > #include <dm/uclass-internal.h>
> > > > > > @@ -695,6 +696,44 @@ int blk_unbind_all(int if_type)
> > > > > > return 0;
> > > > > > }
> > > > > >
> > > > > > +int blk_create_partitions(struct udevice *parent)
> > > > > > +{
> > > > > > + int part, count;
> > > > > > + struct blk_desc *desc = dev_get_uclass_plat(parent);
> > > > > > + struct disk_partition info;
> > > > > > + struct disk_part *part_data;
> > > > > > + char devname[32];
> > > > > > + struct udevice *dev;
> > > > > > + int ret;
> > > > > > +
> > > > > > + if (!CONFIG_IS_ENABLED(PARTITIONS) ||
> > > > > > + !CONFIG_IS_ENABLED(HAVE_BLOCK_DEVICE))
> > > > > > + return 0;
> > > > > > +
> > > > > > + /* Add devices for each partition */
> > > > > > + for (count = 0, part = 1; part <= MAX_SEARCH_PARTITIONS; part++) {
> > > > > > + if (part_get_info(desc, part, &info))
> > > > > > + continue;
> > > > > > + snprintf(devname, sizeof(devname), "%s:%d", parent->name,
> > > > > > + part);
> > > > > > +
> > > > > > + ret = device_bind_driver(parent, "blk_partition",
> > > > > > + strdup(devname), &dev);
> > > > > > + if (ret)
> > > > > > + return ret;
> > > > > > +
> > > > > > + part_data = dev_get_uclass_plat(dev);
> > > > > > + part_data->partnum = part;
> > > > > > + part_data->gpt_part_info = info;
> > > > > > + count++;
> > > > > > +
> > > > > > + device_probe(dev);
> > > > > > + }
> > > > > > + debug("%s: %d partitions found in %s\n", __func__, count, parent->name);
> > > > > > +
> > > > > > + return 0;
> > > > > > +}
> > > > > > +
> > > > > > static int blk_post_probe(struct udevice *dev)
> > > > > > {
> > > > > > if (IS_ENABLED(CONFIG_PARTITIONS) &&
> > > > > > @@ -713,3 +752,75 @@ UCLASS_DRIVER(blk) = {
> > > > > > .post_probe = blk_post_probe,
> > > > > > .per_device_plat_auto = sizeof(struct blk_desc),
> > > > > > };
> > > > > > +
> > > > > > +static ulong blk_part_read(struct udevice *dev, lbaint_t start,
> > > > > > + lbaint_t blkcnt, void *buffer)
> > > > > > +{
> > > > > > + struct udevice *parent;
> > > > > > + struct disk_part *part;
> > > > > > + const struct blk_ops *ops;
> > > > > > +
> > > > > > + parent = dev_get_parent(dev);
> > > > >
> > > > > What device type will the parent have if it is a eMMC hardware partition?
> > > > >
> > > > > > + ops = blk_get_ops(parent);
> > > > > > + if (!ops->read)
> > > > > > + return -ENOSYS;
> > > > > > +
> > > > > > + part = dev_get_uclass_plat(dev);
> > > > >
> > > > > You should check that we do not access the block device past the
> > > > > partition end:
> > > >
> > > > Yes, I will fix all of checks.
> > > >
> > > > > struct blk_desc *desc = dev_get_uclass_plat(parent);
> > > > > if ((start + blkcnt) * desc->blksz < part->gpt_part_info.blksz)
> > > > > return -EFAULT.
> > > > >
> > > > > > + start += part->gpt_part_info.start;
> > >
> > > A better solution is:
> > > if (start >= part->gpt_part_info.size)
> > > return 0;
> > >
> > > if ((start + blkcnt) > part->gpt_part_info.size)
> > > blkcnt = part->gpt_part_info.size - start;
> > > start += part->gpt_part_info.start;
> > > instead of returning -EFAULT.
> > > (note that start and blkcnt are in "block".)
> >
> > What is your motivation to support an illegal access?
> >
> > We will implement the EFI_BLOCK_IO_PROTOCOL based on this function. The
> > ReadBlocks() and WriteBlocks() services must return
> > EFI_INVALID_PARAMETER if the read request contains LBAs that are not
> > valid.
>
> I interpreted that 'LBA' was the third parameter to ReadBlocks API,
> and that if the starting block is out of partition region, we should
> return an error (and if not, we still want to trim IO request to fit
> into partition size as other OS's API like linux does).
> Do you think it's incorrect?

[..]

Related to this patch I think that the partition type should be really
be a child of the media device:

- MMC
|- BLK
|- PARTITION
|- BLK
|- PARTITION
|- BLK
|- PARTITION
|- BLK

It seems more natural to me that putting the partitions under the
top-level BLK device, so that BLK remains a 'terminal' device.

The partition uclass is different from BLK, of course. It could
contain information about the partition such as its partition number
and UUID.

Regards,
Simon