small bug in unlink(2) manpage

small bug in unlink(2) manpage

[Hendrik Jan Thomassen]

This is a report about a small bug in the manpage for the
unlink(2) system call. I found the bug in my Ubuntu 10.10
distribution; its Colophon says: "This  page  is  part  of
release  3.23  of the Linux man-pages project".

The bug is also present in the on-line manpages at
    http://www.kernel.org/doc/man-pages/online_pages.html

The current version of the page says (under ERRORS):

> EBUSY (not on Linux)
>  The  file pathname cannot be unlinked because it is being
>  used by the system or another process and the
>  implementation considers this an error.

But if you look in the kernel source file   fs/namei.c
at routine  may_delete()  you'll see two occasions where
an EBUSY is generated. So the above "not on Linux" is wrong.

I suggest that this '(not on Linux)' be removed. It may
also improve the page if the commentary is reworded to give a
better description of the two situations. Something along
the lines of:
> The file pathname cannot be unlinked because it is being used
> by the system, e.g. if some (relative) rootdir is mounted upon it,
> or because the NFS client software created it to represent an
> active but otherwise nameless inode ("NFS silly renamed").

Just FYI: the NFS silly rename (you'll find this term mentioned
in the kernel source code) is described at:
	http://nfs.sourceforge.net/#section_d
under section D2. The reason I found this manpage bug is because
I stumbled upon one of these silly renamed files, and an strace
of the rm-command revealed the EBUSY return errno.

I am not a native English speaker, so my text can certainly
be improved upon.

Regards,
-- 
Hendrik-Jan Thomassen     <hjt-Hf+EfML1qzhUecB6AVeNQA@public.gmane.org>
AT Computing
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Re: small bug in unlink(2) manpage

[Michael Kerrisk]

Hello Hendrik,

On Thu, Aug 11, 2011 at 10:17 AM, Hendrik Jan Thomassen
<hjt-I2/4/b2VdYhUecB6AVeNQA@public.gmane.org> wrote:
>
> This is a report about a small bug in the manpage for the
> unlink(2) system call. I found the bug in my Ubuntu 10.10
> distribution; its Colophon says: "This  page  is  part  of
> release  3.23  of the Linux man-pages project".
>
> The bug is also present in the on-line manpages at
>    http://www.kernel.org/doc/man-pages/online_pages.html
>
> The current version of the page says (under ERRORS):
>
>> EBUSY (not on Linux)
>>  The  file pathname cannot be unlinked because it is being
>>  used by the system or another process and the
>>  implementation considers this an error.
>
> But if you look in the kernel source file   fs/namei.c
> at routine  may_delete()  you'll see two occasions where
> an EBUSY is generated. So the above "not on Linux" is wrong.
>
> I suggest that this '(not on Linux)' be removed. It may
> also improve the page if the commentary is reworded to give a
> better description of the two situations. Something along
> the lines of:
>> The file pathname cannot be unlinked because it is being used
>> by the system, e.g. if some (relative) rootdir is mounted upon it,
>> or because the NFS client software created it to represent an
>> active but otherwise nameless inode ("NFS silly renamed").
>
> Just FYI: the NFS silly rename (you'll find this term mentioned
> in the kernel source code) is described at:
>        http://nfs.sourceforge.net/#section_d
> under section D2. The reason I found this manpage bug is because
> I stumbled upon one of these silly renamed files, and an strace
> of the rm-command revealed the EBUSY return errno.
>
> I am not a native English speaker, so my text can certainly
> be improved upon.

Thanks very much for this report. For man-pages-3.33, I applied the
change below.

Cheers,

Michael

--- a/man2/unlink.2
+++ b/man2/unlink.2
@@ -69,11 +69,14 @@ did not allow search permission.
 (See also
 .BR path_resolution (7).)
 .TP
-.BR EBUSY " (not on Linux)"
+.BR EBUSY
 The file
 .I pathname
 cannot be unlinked because it is being used by the system
-or another process and the implementation considers this an error.
+or another process;
+for example, it is a mount point
+or the NFS client software created it to represent an
+active but otherwise nameless inode ("NFS silly renamed").
 .TP
 .B EFAULT
 .I pathname

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface"; http://man7.org/tlpi/
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