Bug#324900: nscd: umount /var fails (unclean shutdowns)
On Fri, Aug 26, 2005 at 09:47:51AM +0900, GOTO Masanori wrote:
> At Thu, 25 Aug 2005 17:57:00 -0400,
> Daniel Jacobowitz wrote:
> > On Thu, Aug 25, 2005 at 05:53:05PM +0200, Zlatko Calusic wrote:
> > > GOTO Masanori <firstname.lastname@example.org> writes:
> > >
> > > > At Thu, 25 Aug 2005 12:56:04 +0200,
> > > > Zlatko Calusic wrote:
> > > >> rc 1119 root mem REG 8,9 217016 228931 /var/db/nscd/passwd
> > Note, this is a long-running bash. Not many people use file-rc (that's
> > what this is, right?)
> It explains why most people don't see this issue. Why does file-rc
> cause problems?
> > Does glibc open the nscd cache files directly rather than communicating
> > with it via a socket? Or does it communicate via shared memory?
> Quick look at the source, mmap is used to share database file with
> mmap MAP_SHARED, so the main communication should be done via a
Well, if glibc (rather than NSCD) is opening the file with a shared
mapping, that might explain the problem unmounting /var. Really, the
problem is caused by having file-rc keep a long-running bash open, and
bash needing to talk to nscd.
> > > rc 827 root mem REG 8,9 217016 228931 /var/db/nscd/passwd
> > [Is /var/db even FHS?]
> FHS states as follows.
> 5.5.2 /var/lib/misc : Miscellaneous variable data
> This directory contains variable data not placed in a subdirectory in
> /var/lib. An attempt should be made to use relatively unique names in
> this directory to avoid namespace conflicts.
> Note that this hierarchy should contain files stored in /var/db in
> current BSD releases. These include locate.database and mountdtab, and
> the kernel symbol database(s).
> LDAP or DB data sometimes puts their db files on /var/lib/misc (I
> think "misc" is vague term, though). Actually
> debian/patches/fhs-linux-paths.dpatch contains the following changes:
> --- glibc-2.1.1/sysdeps/unix/sysv/linux/paths.h~ Thu May 27 13:16:33 1999
> +++ glibc-2.1.1/sysdeps/unix/sysv/linux/paths.h Thu May 27 13:17:55 1999
> @@ -71,7 +71,7 @@
> /* Provide trailing slash, since mostly used for building pathnames. */
> #define _PATH_DEV "/dev/"
> #define _PATH_TMP "/tmp/"
> -#define _PATH_VARDB "/var/db/"
> +#define _PATH_VARDB "/var/lib/misc/"
> Another chioce is to use /var/cache - it's for application specific
> caching data. But currently I use /var/db instead of /var/lib/misc -
> I have wondered this change is widely accepted. I would like to hear
> from all you guys about this placement.
This makes me think we ought to be using /var/lib/misc, then, rather
than /var/db - or else just /var/lib. I've never really understood the
difference between lib and cache in var.