misc/123019: mkdir(2) can return EMLINK, but EMLINK is not listed as possible error code in mkdir(2) manpage

[Oleg Koreshkov]

>Number:         123019
>Category:       misc
>Synopsis:       mkdir(2) can return EMLINK, but EMLINK is not listed as possible error code in mkdir(2) manpage
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          doc-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Apr 23 16:00:02 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Oleg Koreshkov
>Release:        6.3-RELEASE
>Organization:
a lot of
>Environment:
FreeBSD 6.3-RELEASE-p2 i386
>Description:
Create directory that contains 32766(7?) subdirectories.
try to create another one subdirectory and you would get:
mkdir: Too many links

However man 2 mkdir doesn't list EMLINK in ERRORS section.

It looks like it happen due to overflow of st_nlink in inode,
but nlink_t is defined as __uint16_t in /usr/include/sys/_types.h:
typedef       __uint16_t      __nlink_t;      /* link count */

So there should be possible to create 65534 subdirectories?
>How-To-Repeat:
Create directory that contains 32766(7?) subdirectories.
try to create another one subdirectory and you would get:

# ls -al | wc -l
   32768
# mkdir 9999999999999
mkdir: 9999999999999: Too many links
>Fix:
For example you can update mkdir(2) manpage with following patch:

--- mkdir.2     2008-04-23 19:42:06.000000000 +0400
+++ mkdir.2     2008-04-23 19:45:13.000000000 +0400
@@ -104,6 +104,8 @@
 .Fa path
 argument
 points outside the process's allocated address space.
+.It Bq Er EMLINK
+The directory contains too many subdirectories.
 .El
 .Sh SEE ALSO
 .Xr chmod 2 ,

>Release-Note:
>Audit-Trail:
>Unformatted: