Messages in this thread | | | Date | Sun, 25 Sep 2005 17:05:17 -0700 | From | Shaun Savage <> | Subject | get partition size of block device from another block device. |
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HI All
I am writing a block device driver that uses another block device for its "base storage".
First the block device sturctures questions. there is one 'struct gendisk' per disk. with partitions under this ->part[N]. there is one 'struct block_device' is the file system device, one per disk or one part partition? Is ther one kobject for each disk or partition?
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one of the module parameters passed in is the base device. eather /dev/hda1 or 0x0301, which format is the best? module_parm_array(str_dev, charp, &dev_cnt,0); or module_parm_array(dev_dev, ushort, &dev_cnt,0);
from string to gendisk bdev = lookup_bdev(str_dev); then finds the block_device gd = get_gendisk(bdev->bd_dev,MINOR(bdev->bd_dev))
OR
gd= get_gendisk(dev_dev,MINOR(dev_dev)) bdev = bdget_disk(gd, MINOR(dev_dev)) This confuses me, if there is one gendisk per disk why does get_gendisk need a partition number?
OR
something with kobject?
---------------------------------------------------------- Now to get ther size. numberOfSectors =gd->part[MINOR(dev)]->nr_sects
Now I need to 'open' the device for r/w bd_claim() or open_bdev_excl()
Now read and write data to the sub block device
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