On Tue, 15 Jul 2008, Jonathan Loran wrote: > Ian Kent wrote: > > On Tue, 2008-07-15 at 13:48 -0700, Chris Walker wrote: > > > > > > When statfs() is called on an automounted directory, it returns before > > > the automount occurs. This results in output like this initially:
> > That may be because there are a group of system calls that don't trigger > > a mount because we have to avoid mount storms for map entries that use > > the browse option. In particular stat(2) and calls that use the same > > kernel path lookup flags, such as statfs(2). > > I need to say that this basically has to be declared a bug. I see this two ways. First, for the folks who have giant NAS boxes with a thousand exported filesysems, if ghost mounts (visibility on the client of non-mounted filesystems) are turned on and someone does "ls -F /net/nasbox" the resulting mount storm, when it stats every exported directory, is a serious pain in the butt, and when ghost mounts (browsing) were introduced there was a lot of howling until the mount storms were tamed. On the other hand, the issue is Not Autofs' Problem, and if stat() or statfs() is directed at a nonlocal directory, information about its referent should be returned, not about the soon-to-be-underlying mount point. "ls", Nautilus, etc. are supposed to use mental telepathy to avoid causing mount storms; it is not autofs' place to interpret why the information is wanted and whether major resources should be expended to make it available. Actually, only the sysop knows which is more important: doing the mount storm to respond to stat() or statfs(), or avoiding the storm. Could we have two kinds of browsing, with or without mount storms, i.e. with or without a response to stat() or statfs()? This would be configurable the same way browsing is, individually per map row. The default should be to do the mount, because most sites export a reasonable number of filesystems from each server and so the mount storm is not a big deal, but a sysop who exports lots of directories from one NAS box and also turns on browsing in the client is advised to pick the non-mounting browse variant. James F. Carter Voice 310 825 2897 FAX 310 206 6673 UCLA-Mathnet; 6115 MSA; 520 Portola Plaza; Los Angeles, CA, USA 90095-1555 Email: [EMAIL PROTECTED] http://www.math.ucla.edu/~jimc (q.v. for PGP key) _______________________________________________ autofs mailing list autofs@linux.kernel.org http://linux.kernel.org/mailman/listinfo/autofs
