Block I/O sizes

[Block Device <blockdevice@gmail.com>]

Hi,

   I've added a jprobe to generic_make_request and am print(k)ing the
bio->bi_sector and
   bio_sectors(bio) for every bio.

   I expected that for every bio thus printed the bi_sector would be
in terms of sector size.
   But this is apparently not the case.

    When any fs i/o is done, the bi_sector value is in terms of fs
block size and not sector size (for the block device). When i perform
raw i/o to the device ( dd for eg ), bi_sector is in terms of sectors
and not fs blocks.

    In both the cases though, bio_sectors(bio) returns the amount of
data written in sectors.

To me this is rather strange. Should it not be in terms of sector size always ?
 Can someone please explain ?

Thanks
-BD