On Mon, Oct 17, 2016 at 03:29:23PM +0200, Michael Grzeschik wrote:
> With this patch it is possible to write an mbr partition table to the
> mci block device. By setting the device property "dos_partitions" of the
> mmc device node, it is possible to write back the new partition layout
> in the common cmdlinepart notation. The property can also be read back.
>
> Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
> ---
> drivers/mci/mci-core.c | 122 +++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 122 insertions(+)
>
> diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
> index 4e176f7..c0013a1 100644
> --- a/drivers/mci/mci-core.c
> +++ b/drivers/mci/mci-core.c
> @@ -33,9 +33,11 @@
> #include <asm-generic/div64.h>
> #include <asm/byteorder.h>
> #include <block.h>
> +#include <fcntl.h>
> #include <disks.h>
> #include <of.h>
> #include <linux/err.h>
> +#include <cmdlinepart.h>
>
> #define MAX_BUFFER_NUMBER 0xffffffff
>
> @@ -1527,6 +1529,122 @@ static void mci_info(struct device_d *dev)
> extract_mtd_year(mci));
> }
>
> +static char *print_size(uint64_t s)
> +{
> + if (!(s & ((1 << 20) - 1)))
> + return basprintf("%lldM", s >> 20);
> + if (!(s & ((1 << 10) - 1)))
> + return basprintf("%lldk", s >> 10);
> + return basprintf("0x%lld", s);
s/lld/llx/
> +}
> +
> +static int print_part(char *buf, int bufsize, struct cdev *cdev, int is_last)
> +{
> + char *size = print_size(cdev->size);
> + int ret;
> +
> + if (!size) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + ret = snprintf(buf, bufsize, "%s(%s)%s", size,
> + cdev->partname,
> + is_last ? "" : ",");
> +out:
> + free(size);
> +
> + return ret;
> +}
> +
> +static int print_parts(char *buf, int bufsize, struct mci *mci)
> +{
> + struct cdev *cdev, *ct;
> + int ret = 0;
> +
> + list_for_each_entry_safe(cdev, ct, &mci->dev.cdevs, devices_list) {
safe_?
> + if ((cdev->flags & DEVFS_IS_PARTITION) &&
> + (cdev->flags & DEVFS_PARTITION_IN_PT)) {
> + int now;
> + int is_last = 0;
> + struct list_head *nh = (cdev)->devices_list.next;
> + struct cdev *next = container_of(nh, typeof(*(cdev)), devices_list);
> +
> + if (list_is_last(&cdev->devices_list, &mci->dev.cdevs) ||
> + !(next->flags & DEVFS_PARTITION_IN_PT))
> + is_last = 1;
Is this test safe? What if the next partition does not have the
DEVFS_PARTITION_IN_PT flag set, but the one after that has? Maybe you
have to count the number of partitions in a first pass.
> +
> + now = print_part(buf, bufsize, cdev, is_last);
> + if (now < 0)
> + return now;
> +
> + if (buf && bufsize) {
> + buf += now;
> + bufsize -= now;
> + }
> + ret += now;
> + }
> + }
> +
> + return ret;
> +}
> +
> +static const char *mci_partition_get(struct device_d *dev, struct param_d *p)
> +{
> + struct mci *mci = container_of(dev, struct mci, dev);
> + int len = 0;
> +
> + free(p->value);
> +
> + len = print_parts(NULL, 0, mci);
> + p->value = xzalloc(len + 1);
> + print_parts(p->value, len + 1, mci);
> +
> + return p->value;
> +}
> +
> +#ifdef CONFIG_BLOCK_WRITE
> +static int mci_partition_set(struct device_d *dev, struct param_d *p, const char *val)
> +{
> + struct mci *mci = container_of(dev, struct mci, dev);
> + struct cdev *cdev, *ct;
> + int ret;
> +
> + if (!val)
> + return -EINVAL;
> +
> + /* remove all partition cdevs with DEVFS_IS_PARTITION set */
> + list_for_each_entry_safe(cdev, ct, &mci->dev.cdevs, devices_list) {
> + if ((cdev->flags & DEVFS_IS_PARTITION) &&
> + (cdev->flags & DEVFS_PARTITION_IN_PT))
> + ret = devfs_del_partition(cdev->name);
> + if (ret)
> + return ret;
> + }
> +
> + /* read back the prepared partition layot from dos_partitions param */
s/layot/layout/
> + ret = cmdlinepart_do_parse(mci->cdevname, val, mci->capacity,
> + CMDLINEPART_ADD_DEVNAME | CMDLINEPART_ADD_TO_PT);
> + if (ret)
> + return ret;
> +
> + /* write the MBR partition layout based on cdevs with DEVFS_IS_PARTITION set */
> + for (int i = 0; i < mci->nr_parts; i++) {
> + struct mci_part *part = &mci->part[i];
> + if (part->area_type == MMC_BLK_DATA_AREA_MAIN) {
> + ret = write_dos_partition_table(&part->blk,
> + &mci->dev.cdevs);
> + if (ret != 0) {
> + dev_warn(&mci->dev, "Could not write partition table\n");
> + return ret;
> + }
> + }
> + }
> +
> + return ret;
> +}
> +#endif
> +
> /**
> * Check if the MCI card is already probed
> * @param mci MCI device instance
> @@ -1786,6 +1904,10 @@ int mci_register(struct mci_host *host)
> mci->param_probe = dev_add_param_bool(&mci->dev, "probe",
> mci_set_probe, NULL, &mci->probe, mci);
>
> +#ifdef CONFIG_BLOCK_WRITE
> + dev_add_param(&mci->dev, "dos_partitions", mci_partition_set, mci_partition_get, 0);
> +#endif
Use IS_ENABLED()
Other than that this code should be attached to parse_partition_table()
rather than making this mci specific.
We probably can safely write a dos partition table to an unpartitioned
device, but should refuse to create/manipulate a dos partition table
when a EFI partition table exists.
Sascha
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