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

Simon Glass
2021-10-11T16:14:22Z

Hi Heinrich,

On Mon, 11 Oct 2021 at 09:02, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
>
>
>
> On 10/11/21 16:54, Simon Glass wrote:
> > 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.
>
> Do you mean hardware partition here? Otherwise I would not know what BLK
> should model.

I mean that (I think) we should not use BLK to model partitions. A BLK
should just be a block device.

I don't see any difference between a partition and a hardware
partition. We presumably end up with a hierarchy though. Do we need a
HWPARTITION uclass so we can handle the hardware partitions
differently?

Regards,
Simon