Re: [Ext2-devel] Re: Htree ate my hard drive, was: post-halloween 0.2

On Thu, Oct 31, 2002 at 01:19:23PM +0200, Petr Vandrovec wrote:
> On 31 Oct 02 at 9:20, Duncan Sands wrote:
> > > I wonder if there is still a bug in the e2fsck code for re-hashing
> > > directories?  It shouldn't be possible to have e2fsck complete and
> > > there still be an error in the filesystem (ok, sometimes it happens,
> > > but in those cases it spews a lot of warnings about the filesystem
> > > not being fixed yet and to run manually).
> > 
> > It is possible that the filesystem was fine when fsck completed, but
> > was damaged afterwards, i.e. in the time between fsck completing
> > and the reboot.
> 
> Just stupid idea. Two or three months ago I complained that if
> my box crashes shortly after boot, following things happen:
> 
> (1) system for some reason reads /var/run directory to page cache
> (2) fsck finds that /var/run/* entries points to invalid nodes, and
>     removes them (through block device access)
> (4) / is remounted read-write    
> (5) because of page cache for block device and directory is not
>     coherent (or what...), system still sees /var/run/* populated
> (6) rm /var/run/* is run. FS is remounted read-only due to
>     freeing inode already freeed...
> (7) Reboot, run fsck again, reboot, fine...
>     
> Nobody answered it at that time, and it happened at least 5 times
> again to me - until I modified initscripts to do unconditional
> reboot if "fsck /" did ANY modifications to filesystem.
> 
> Maybe kernel still uses old directory indexes structure after
> fsck created new one?

File system needs to unmount and remount after e2fsck packed
directory index. Kernel need to trash all the dentry cache of
that file system. If you pack the "/". It'd better reboot.

Chris