How to get the inode - no path_lookup

[Rishi Agrawal]

On Thu, Aug 9, 2012 at 12:39 PM, Rohan Puri <rohan.puri15 at gmail.com> wrote:

>
>
> On Thu, Aug 9, 2012 at 8:45 AM, Rishi Agrawal <rishi.b.agrawal at gmail.com>wrote:
>
>>
>>
>> On Wed, Aug 8, 2012 at 12:46 PM, Rohan Puri <rohan.puri15 at gmail.com>wrote:
>>
>>>
>>>
>>> On Tue, Aug 7, 2012 at 8:11 PM, Rishi Agrawal <rishi.b.agrawal at gmail.com
>>> > wrote:
>>>
>>>> Hi All,
>>>>
>>>>
>>>> I had a module which used the path_lookup function to print the details
>>>> of any file's inode. I now want to rewrite that module in order to show
>>>> some juniors how to write some code in kernel.
>>>>
>>>> I am using 3.4.6 kernel, I tried finding out path_lookup but google
>>>> showed that it has been removed.
>>>>
>>>> I tried the following code then which did not work
>>>>
>>>> .
>>>> .
>>>> .
>>>> dentry = kern_path_create(AT_FDCWD, filename, &path, 1);
>>>>
>>>> if (IS_ERR(dentry)) {
>>>>               printk("Failed to obtain the dentry");
>>>>                return;
>>>>        }
>>>>
>>>> its not returning dentry
>>>>
>>>> I again tried after seeing the implementation of vfs_stat function
>>>>
>>>> user_path_at(AT_FDCWD, filename, lookup_flags, &path);
>>>>
>>>> but this also fails.
>>>>
>>>>
>>>> I am using a proc interface to pass the filename, and copying the
>>>> filename into a kernel buffer.
>>>>
>>>> How can I get a copy of vfs inode for a file name.
>>>>
>>>>
>>>> Need to use vfs_path_lookup for this, present in fs/namei.c file, which
>>> would give you filled nameidata nd that contais inodes pointer.
>>>
>>>> --
>>>> Regards,
>>>> Rishi Agrawal
>>>>
>>>>
>>>> _______________________________________________
>>>> Kernelnewbies mailing list
>>>> Kernelnewbies at kernelnewbies.org
>>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>>>>
>>>>
>>> - Rohan
>>>
>>
>> vfs_path_lookup needs a dentry/mountpoint for the current path.
>>
>> How will I get those.
>>
>>
>> /**
>>  * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
>>  * @dentry:  pointer to dentry of the base directory
>>  * @mnt: pointer to vfs mount of the base directory
>>  * @name: pointer to file name
>>  * @flags: lookup flags
>>  * @path: pointer to struct path to fill
>>  */
>>
>>
>> --
>> Regards,
>> Rishi Agrawal
>>
>> If you dont have vfsmount's ptr, then you can make use of kern_path api
> with the LOOKUP_FOLLOW as second parameter. This will return the struct
> path ptr which contains vfsmount and the dentry's ptr. Now the dentry's ptr
> will contain the inode that you require.
>
> - Rohan
>

Thanks, used that and its working now

-- 
Regards,
Rishi Agrawal
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