Hi Rohit,
Take a look into how get_empty_filp() is implemented (fs/file_table.c).
get_empty_file()
{
It calls kmem_cache_zalloc() to allocate memory for the struct file *. This function sets the allocated memory to 0.
Then it sets few of the fields of struct file like
f_count = 1
f_uid = current_task->fsuid
f_gid = current_task->fsgid
and then returns the struct file *.
}
It does not set any other fields that's the reason you get f_vfsmnt as NULL.
get_empty_file() just creates a new and empty struct file, it does not accept any file system to associate with. There could be number of file systems on the machine. So, it won't associate by himself to any filesystem.
Thanks and Regards,
Prasad
Take a look into how get_empty_filp() is implemented (fs/file_table.c).
get_empty_file()
{
It calls kmem_cache_zalloc() to allocate memory for the struct file *. This function sets the allocated memory to 0.
Then it sets few of the fields of struct file like
f_count = 1
f_uid = current_task->fsuid
f_gid = current_task->fsgid
and then returns the struct file *.
}
It does not set any other fields that's the reason you get f_vfsmnt as NULL.
get_empty_file() just creates a new and empty struct file, it does not accept any file system to associate with. There could be number of file systems on the machine. So, it won't associate by himself to any filesystem.
Thanks and Regards,
Prasad
On Mon, Sep 22, 2008 at 10:27 PM, Rohit Sharma <imreckless@xxxxxxxxx> wrote:
I am interested in getting the vfsmount structure of the mounted file
system from my module.
I used filp = get_empty_filp() (filp is file pointer)
function to create an empty file object (as this contains pointer to
vfsmount structure)
file object has a field f_vfsmnt which points to the vfsmount structure
i am storing this in my own my_vfsmnt structure of type vfsmount.
my_vfsmnt = filp->f_vfsmnt
but i am getting my_vfsmnt as NULL ??
is there any other way of getting the vfsmount structure ??
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