24.07.2016 07:32, Tomasz Melcer пишет: > On 24.07.2016 04:16, Chris Murphy wrote: >> On Sat, Jul 23, 2016 at 8:03 PM, Tomasz Melcer <li...@exroot.org> wrote: >>> How can I ask btrfs to recompute the checksum of a data block as it is >>> stored on the drive? >> >> Since btrfs-progs 3.17 'btrfs check --init-csum-tree' will create a >> whole new csum tree. > > I can't make this command recalculate only checksum of that single file? > >
Rewriting single block in question should do it. As you can read from raw device and have both physical and logical block address something like dd if=/dev/sdd1 skip=222940168 count=8 | dd of=/path/to/dysk/dysk.bin seek=189669768 conv=notrunc count=8 If you have possibility to verify file content(s), this technique can be used to read over unreadable parts of file by combining multiple dd's from file and device. It probably makes sense to create (read-only) snapshot to make sure you have old content available. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
