Messages in this thread | | | Date | Mon, 29 Oct 2012 15:54:21 -0700 | From | Greg KH <> | Subject | Re: [RFC v4+ hot_track 13/19] debugfs: introduce one function |
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On Tue, Oct 30, 2012 at 06:45:19AM +0800, Zhi Yong Wu wrote: > On Tue, Oct 30, 2012 at 6:34 AM, Greg KH <gregkh@linuxfoundation.org> wrote: > > On Tue, Oct 30, 2012 at 06:25:50AM +0800, Zhi Yong Wu wrote: > >> On Tue, Oct 30, 2012 at 2:11 AM, Greg KH <gregkh@linuxfoundation.org> wrote: > >> > On Mon, Oct 29, 2012 at 12:30:55PM +0800, zwu.kernel@gmail.com wrote: > >> >> From: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com> > >> >> > >> >> The debugfs function is used to get expected dentry. > >> > > >> > Huh? Why do you need this? Why haven't you added documentation for the > >> It is used to determine if one sysfs directory has been created. OK, i > >> will add some doc, thanks for your suggestion. > > > > You didn't answer the "why" part here. How come you think you need > ah, Let me say its scenario at first. If we do two mount ops as below: > 1.) mount -o loop,hot_track image1 /data1 > 2.) mount -o loop,hot_track image2 /data2 > > The mount -o hot_track operation will automatically create one sysfs > directory /sys/kernel/debug/hot_track. To prevent this dir being > created again when 2.) is done, we need to know if it has existed at > first. In my patch, i at first get its dentry by this new function, > then determine if its d_inode field is NULL, if no, it means that this > sysfs dir has existed. > This is the reason that i want to add one new function.
Why not do like the rest of the kernel does and just have a: static dentry *hot_track_root; and use that as your root debugfs directory dentry:
if (!hot_track_root) { /* Create root directory */ hot_track_root = debugfs_create(...); }
No need to look anything up :)
thanks,
greg k-h
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