Re: file system question

[kapil a <kapilann@gmail.com>]

---------- Forwarded message ----------
From: kapil a <kapilann@gmail.com>
Date: Feb 8, 2006 7:11 PM
Subject: Re: file system question
To: Avishay Traeger <atraeger@cs.sunysb.edu>


thanks for the reply and sorry for the unclear question.

What i meant was when i do an "ls" in a directory that is part of the
ext2 filesystem, i can see a  "write" call in the strace output at the
end and it writes the directory contents to stdout. However when i
issue "ls" in the mount point of my file system, i dont have the
"write" call. The strace ends with the getdents64 call.

When i did some debugging i found that filldir which is suppose to
fill the dirent with the directory entries does its job. My filesystem
currently has only one inode with one block of data where i have a
".", ".." and "test" written into it.

The problem is it does not go further to do some of the other calls as
in a mountpoint in ext2 file system.

Hope i am clear now.

kaps


On 2/8/06, Avishay Traeger <atraeger@cs.sunysb.edu> wrote:
> On Wed, 2006-02-08 at 18:39 -0500, kapil a wrote:
> > I am trying to write a file system for 2.6.  I have written the
> > required things to mount my file system and now i am trying to get
> > some f_op's and d_op's. I was trying to make the 'ls' command work. So
> > i wrote a myfs_readdir() and linked it to the f_op field. My routine
> > gets called and also filldir gets called and stores the data in the
> > dirent but i dont get the output in stdout.
> >
> >   On using strace i find that "ls" does not perform all the calls that
> > a "ls" in a directory mountedf in ext2 performs. To be specific, the
> > strace ouput ends after the getdents64 system call. In the normal "ls"
> > strace, i find there are a couple of more system calls namely a fstat
> > followed by a write to stdout and some more mmap calls.
>
> Correct.  The getdents system call will call your readdir function.
>
> >   I dont understand the reason behind why the write is not called. My
> > guess is i have not over-ridden some function that i have to write as
> > part of my file system instead of using the default method.
>
> Why would your write function get called when 'ls' writes to stdout?
> Please explain your question more clearly.
>
>
> Avishay Traeger
> http://www.fsl.cs.sunysb.edu/~avishay/
>
>