Red Hat Bugzilla – Bug 76618
ypserv file handle caching code causes map files to remain locked even when not in use
Last modified: 2015-01-07 19:01:20 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0 Description of problem: With the new ypserv file handle caching code in "yp_db.c" since version 2.x, which comes with Redhat 7.3 and above the maps are not closed till ypserv is stopped. This results in the map files remaining locked once a ypcat or a similar command is issued. Event though the ypcat command completes the map files remain locked. Due to this other programs (such as ours) which try to open the map files fail as they are unable to acquire the file lock while calling "gdbm_open". Though it may not be possible for performance reasons to dump the file handle caching code, there definitely must be a way to disable file handle caching. Though the "ypserv.conf" file has a "files: <num>" setting by which one would assume that if we set the <num> value to 0, no file handles would be cached, this does not seem to work. Looking at the code it seems that the value read from the "ypserv.conf" file is read into a variable "cached_filehandles" but is then just discarded. Instead a hardcoded value of 30 is used via a macro for MAX_FOPEN. There should be atleast be a way to disable file handle caching if the locks cant be released. This issue does not exist with Redhat 7.2 which uses ypserv 1.3.x. Version-Release number of selected component (if applicable): How reproducible: Always Steps to Reproduce: 1.Configure NIS and start ypserv and start ypbind to bind to this ypserv run the ypserv in debug mode. 2.run ypcat passwd.byname ( with the maps already populated ) 3. cat /proc/locks shows the FLOCK (READ lock) being retained by ypserv even though ypcat has completed. Actual Results: The cat command above shows FLOCK (READ lock) being retained by ypserv even though the debug log shows "ypdb_close() called". ( This actually doesnt call the actual "gdbm_close()" due to file handle caching) Expected Results: The FLOCK should have been cleared upon the ypdb_close() or the file handle caching should be configurable via the "ypserv.conf" files: setting Additional info:
Yeah. Disabling it should work. I dunno if it is safe to drop the lock in ypdb_close() though. I will look into it.
We have our product that is on the verge of shipping. Our product works fine with Redhat versions 7.2 or lower as of now. It would be very helpful if you could just give an update of the ypserv package for Redhat 7.3 and 8.0 which would have a mechanism of disabling file handle caching. That would be enough for our purposes. It would be very helpful if you could provide this patch as soon as possible.
It's unfortunately worse than that. There has been a recent security-related memory leak in ypserv, and the errata for 7.x include updating to a recent ypserv. See: http://rhn.redhat.com/errata/RHSA-2002-223.html This means you'll have problems on updated 7.2 (etc) machines too. I'll try to take a look at this as soon as I can. We don't normally do bugfix erratas for old releases (except for really major bugs). But at I can produce a patch that you could use and fix it for later RH releases.
We will eagering wait for your fix. Thanx for your prompt responses.
Read "eagering" as "eagerly" !!
I've spoken with the ypserv maintainer. Expect a patch that disables caching if files == 0.
Sorry for the delay. I've been on a meeting the whole last week. I'll take a look at it this week.
It is fixed in ypserv 2.6, availible at: ftp://ftp.kernel.org/pub/linux/utils/net/NIS/ I will build a package in rawhide tomorrow. You can extract a patch from the release if you need it.
I have now built ypserv 2.6 in our system, and it will reach rawhide in a day or so. It should fix your problems (i.e. files=0 will disable caching), and the rawhide package should work on a 8.0 system. If you want to build packages for 7.x the errata ypserv 2.5 package should be a good basis, since 2.5 and 2.6 have few differences.
I will try this out.
Could you let me know the URL where i can find the rawhide packages ? I looked at the ftp.redhat.com site under the .../rawhide/... directory and could not find a ypserv RPM
ftp://ftp.redhat.com/pub/redhat/linux/rawhide/i386/RedHat/RPMS/ypserv-2.6-1.i386.rpm
I am unable to access the RPM with the URL you have given. Could you please check whether the URL is accessable ?
It seems broken in some way. It may be on a mirror somewhere, but anyway i put a copy at: http://people.redhat.com/alexl/RPMS/
I have verified this fix. It is working fine. If you could just get the URL for download fixed we can consider this issue closed. Thanks for your help !!
Hmm. The ypserv package seems to have disappeared from rawhide completely now... notting: Do you have any idea what happened to it?
It's getting pulled into trees, probably a transient push script error.
Nah. It was once there. But got removed somehow.
So when is link going to be up !! We need to provide this link since it doesn't seem to be appropriate asking people to download from "people.redhat.com" !!
There was some sort of problem pushing the latest rawhide packages to the ftp site. The upload died after having removed the old files. I think this has been fixed now though, at least the file is there now. Note that Rawhide itself is a transient entity. It always contains only the latest packages in development. If I do e.g. a bugfix that is scheduled to be in the next release it's gonna end up in rawhide as e.g. ypserv-2.6-2, and the old one (ypserv-2.6-1) will disappear.
I verified that the links are working now. We will provide appropriate instructions for downloading latest versions of ypserv. This issue is closed from our side. Thanks !!