Getting a block from a block device?

[rohan.puri15@gmail.com (rohan puri)]

On Tue, Nov 8, 2011 at 5:26 PM, Dan Luedtke <maildanrl@googlemail.com>wrote:

> Hallo,
>
> On Tue, Nov 8, 2011 at 12:27 PM, Stephen Gream <poisonthemon@gmail.com>
> wrote:
> > Once you have the device registered (on /sys or /dev), register a read
> > callback on the file and use copy_to_user to output the data
>
> I read that article you referred to, but I don't think it addresses my
> problem, as I may have been more clear on what I want to achieve
> before. Sorry for that!
> I want to eventually implement a file system, and therefore I am
> studying the kernel sources to get an idea about all that.
>
> Here is my general understanding on how thinks may work :)
>
> virtual file system (VFS) <-[1]-> my file system implementation
> <-[2]-> a block device
>
> As I understood, all these subsystems are running in kernel mode.
>
> For [1] I read vfs.txt and learned about the VFS-API
> For [2] I have no idea where I can find the API documentation, however
> there were some hints on the book "Linux Driver Development" from
> O'Reilly in chapter "block devices". Nothing really helpful, as they
> were talking about registering new block devices. I want to use
> already present devices where I expect my filesystem to be present on.
> To check that, I have to read the first 512 bytes.
>
> The userspace implementation I was talking about previously is
> something like a mkfs.myfilesystem, that's why i referred to fopen()
> there.
>
> Thank you!
>
> Greetings,
>
> Dan
> --
> Dan Luedtke
> http://www.danrl.de
>
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>
Dan,

You need to look at other block-based file systems in the kernel sources in
fs dir for examples and understand how they do it.

Regards,
Rohan Puri
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