On Thu, Apr 15, 2010 at 8:32 AM, Abhijit Pawar <abhijitcpa...@gmail.com>wrote:
> Hi List,
> I am trying to learn the filesystem development and doing some study.
> I have been working on a sample filesystem module and built a normal
> super_operations struct. It was working on older kernel of 2.6 series till
> 2.6.25 and above. I realized that there were changes made in this structure
> and following fields were removed.
> 1. read_inode
> 2. put_inode
>
> I read on google but there wasnt anything specific mentioned what we need
> to use instead. They also removed iget and suggested to use iget_lock.
>
> Can anyone please let me know what I need to do in order to compile module?
>
> Here is my current structure and errors.
>
> Structure:
>
> static const struct super_operations myfs_sops = {
> .alloc_inode = myfs_alloc_inode,
> .destroy_inode = myfs_destroy_inode,
> .read_inode = myfs_read_inode,
> .put_inode = myfs_put_inode,
> .write_inode = myfs_write_inode,
> .delete_inode = myfs_delete_inode,
> .put_super = myfs_put_super,
> .write_super = myfs_write_super,
> .statfs = myfs_statfs,
> .clear_inode = myfs_clear_inode,
> };
>
>
> errors:
> error: unknown field ‘read_inode’ specified in initializer
> error: unknown field ‘put_inode’ specified in initializer
> error: implicit declaration of function ‘iget’
>
>
> Your help would be highly appreciated. Also can you please let me know how
> should I approach the filesystem development. I am currently reading Steve
> D. Pate's filesystem book, but I am not very sure if it fits for current
> kernel. However the book is clearing lots of concept.
> Please let me know how to develop a sample filesystem.
>
iget and read_inode calls are deprecated now. The idea of was to merge
iget() code into read_inode() to avoid duplication in filesystem code,
among other benefits.
You have to change myfs_read_inode decleration & definition to:
Decleration :
struct inode *myfs_iget(struct super_block *, unsigned long );
Definition :
struct inode *myfs_iget(struct super_block *sb, unsigned long ino)
{
struct inode *inode;
inode = iget_locked(sb, ino);
if(!inode)
return ERR_PTR(-ENOMEM);
if(!(inode->i_state & I_NEW))
return inode;
// Your implementation specific code like initializeing atime,
ctime, mtime, address_space mapping etc. ( depends on what you wanna do with
a new inode )
unlock_new_inode(inode);
return inode;
}
Then,
Change ".read_inode = myfs_read_inode" into ".read_inode = myfs_iget"
Then,
Wherever you call iget in your kernel module, replace that with myfs_iget.
And make sure that you check for error values after calling myfs_iget
because myfs_iget can "potentially" fail.
Regards,
Venkatram Tummala
