Mapping of Filename to allocated blocks

[arshad hussain]

On Thu, Apr 28, 2016 at 7:28 AM, Manoj Rao <linux at manojrajarao.com> wrote:
> Hi All,
>
> I'm looking for a way to get a filename associated with a given physical
> block (ideally what I'd like is a mapping of filename <=> all the allocated
> blocks for this file).

If you have not done already, this could be a good starting point.
Look at FIBMAP IOCTL.

Here is one usage of FIEMAP, demonstrated via hdparam.
# hdparm --fibmap <your file name>

>
> Is there a recommended way to do this already in kernel? if not, then where
> should I start looking to add changes?

Not sure about what would be the Recommended method. But this could be done
in user-space vs doing it in kernel space. For example, consider cases like
single file restore - there will be a requirement to figure out the
logical - physical block allocation for a file which could be achieved
through...
Read superblock
Read dentry - Home into the required inode (file)
Read inode - to figure out the location of block.

Note: This is not generic - and would require changes as layout is different
for filesystems.

Thanks
Arshad