Re: About function __create_file in debugfs

[gregkh <gregkh@linuxfoundation.org>]

On Sat, Sep 08, 2012 at 05:41:05PM +0800, Jianpeng Ma wrote:
> Hi:
> 	At present,i used blktrace to trace block io.But i always met error, the message like:
> >BLKTRACESETUP(2) /dev/sdc failed: 2/No such file or directory
> >Thread 0 failed open /sys/kernel/debug/block/(null)/trace0: 2/No such file or directory
> >Thread 2 failed open /sys/kernel/debug/block/(null)/trace2: 2/No such file or directory
> >Thread 3 failed open /sys/kernel/debug/block/(null)/trace3: 2/No such file or directory
> 
> >Thread 1 failed open /sys/kernel/debug/block/(null)/trace1: 2/No such file or directory
> >FAILED to start thread on CPU 0: 1/Operation not permitted
> >FAILED to start thread on CPU 1: 1/Operation not permitted
> >FAILED to start thread on CPU 2: 1/Operation not permitted
> >FAILED to start thread on CPU 3: 1/Operation not permitted
> 
> But those isn't important. I add some message in kernel and found the reason is inode already existed.
> But the function __create_file dosen't return correctly errno.So blktrace tool can't print correctly message.
> I think func __create_file should return correctly message(ERR_PTR(error)) not NULL.

Patches are always welcome :)

greg k-h