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

Heinrich Schuchardt
2021-10-11T15:03:07Z

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.

Best regards

Heinrich