On Thu, Aug 9, 2012 at 8:45 AM, Rishi Agrawal <[email protected]>wrote:
> > > On Wed, Aug 8, 2012 at 12:46 PM, Rohan Puri <[email protected]>wrote: > >> >> >> On Tue, Aug 7, 2012 at 8:11 PM, Rishi Agrawal >> <[email protected]>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 >>> [email protected] >>> 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
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