Re: File System Address Space Operations

["Martin Jambor" <jambormartin@gmail.com>]

On 7/29/06, UZAIR LAKHANI <uzairr_bs1b@yahoo.com> wrote:
> Hello All,
>
> I want to find out the details of the address space
> operations. Where can I get the detailed information
> about the address space operations.

Have a look at

a) Documentation/filesystems/vfs.txt
b) Documentation/filesystems/Locking and
c) some simple fs that uses it (minix?)

> In  addition  I  want  to  find  out  whether  these  address  space
> operations  are   for  performance  reasons  or   are  mandatory  to
> implement.

No,  I guess  you  could access  the  underlying device  (or a  remote
server) each  time a  filesystem object is  read or written  to.  This
approach would be simple but

a) it  could be very  slow (at least  a block device  based filesystem
   like that would),
b) you basically  wouldn't be able to implement  mmap unless you wrote
   an equivalent of the page cache and
c) when  you use the generic  functions to handle  the file operations
   and only  code the  address space operations,  it is not  that much
   more difficult.

> In addition do distributed file systems on the client
> and server side require to implement address space
> operations e.g. nfs (client side) implements these
> address space operations.

I'm not an expert on  network filesystems but it would probably depend
on whether and what kind of client caching you want.

HTH

Martin