[reiserfs-list] RE: [OpenAFS-devel] weird issue with reiserfs on 2.4.3 and openaf s

[Derek Atkins]

IMHO, this is a bad idea.  I'd rather see reiser-fs fixed to actually
support the exported inode interface.

-derek

"Neulinger, Nathan" <nneul@umr.edu> writes:

> Just for the hell of it, I tried doing the following:
> 
> 	afsd - stat the cache file before telling kernel to open it with
> iget
> 	afs_dcache.c - in kernel code - tell afs_InitCacheFile to
> intentionally leak open files - i.e. when initting the cache files,
> intentionally do not call UFSClose() on the file after the cache file has
> been initialized.
> 
> I'm leery of this as a 'fix', but I am unable to trigger the failure after
> doing this.
> 
> Perhaps it would be reasonable to have the kernel itself keep the files open
> like this, but in a way that it could keep track of them so they can be
> closed later when afs is unmounted.
> 
> I'm not sure how this sort of thing would interact with "max number of open
> files" and things like that though. How do those limit behave inside the
> kernel?
> 
> -- Nathan
> 
> > -----Original Message-----
> > From: Neulinger, Nathan [mailto:nneul@umr.edu]
> > Sent: Wednesday, April 11, 2001 10:36 AM
> > Cc: 'reiserfs-list@namesys.com'; 'openafs-devel@openafs.org'
> > Subject: RE: [reiserfs-list] RE: [OpenAFS-devel] weird issue with
> > reiserfs on 2.4.3 and openaf s
> > 
> > 
> > Ya know, keeping the files open wouldn't be a half bad idea. 
> > Although it
> > does mean that in some cases, the system would have 50,000 
> > (for a 500 MB
> > cache w/ standard options for chunk size) open files sitting 
> > around doing
> > nothing. Seems a bit excessive.
> > 
> > As it stands now with the patch, it just stats the cache 
> > node, then does the
> > kernel msg that triggers the iget/open. The cache node isn't kept open
> > though.
> > 
> > True on your point about it being slow - except that it isn't 
> > actually slow
> > when people put the afscache on it's own filesystem. That's 
> > what we found
> > out with the 2.2.x reiserfs code. 
> > 
> > -- Nathan
> > 
> > > -----Original Message-----
> > > From: Chris Mason [mailto:mason@suse.com]
> > > Sent: Wednesday, April 11, 2001 10:31 AM
> > > To: Neulinger, Nathan
> > > Cc: 'reiserfs-list@namesys.com'; 'openafs-devel@openafs.org'
> > > Subject: RE: [reiserfs-list] RE: [OpenAFS-devel] weird issue with
> > > reiserfs on 2.4.3 and openaf s
> > > 
> > > 
> > > 
> > > 
> > > On Wednesday, April 11, 2001 10:08:41 AM -0500 "Neulinger, Nathan"
> > > <nneul@umr.edu> wrote:
> > > 
> > > > Unfortunately, I can only prime this at afsd startup time. 
> > > Within the
> > > > kernel module, the igets are issued later on when files in afs are
> > > > actually accessed, and at that time, the kernel module 
> > does not know
> > > > anything about the cache filenames, only the inodes. 
> > > > 
> > > 
> > > Hmmm, is a userspace daemon doing the opens on the cache 
> > > files when you
> > > prime the cache?  You might be better off just keeping the 
> > > cache files open
> > > the whole time.  This is easier if they are done by 
> > > userspace, since the
> > > closes will happen if the program dies somehow.
> > > 
> > > > I know y'all don't like that fallback code, and it's 
> > > obviously a worst
> > > > case scenario, but I'd really like to see you add it back 
> > in for the
> > > > simple reason that 'horribly slow' (and in this case, it 
> > > won't be, since
> > > > it's on it's own partition) is better than 'doesn't work at all'.
> > > > 
> > > > I'm not totally averse to adding it back in on my local 
> > > kernel only if we
> > > > can't come up with a better alternative.
> > > > 
> > > 
> > > It is easy to patch in, but it doesn't get the real problem 
> > > solved.  The
> > > problem with keeping the search_by_objectid code is that 
> > > instead of getting
> > > proper interaction with things like AFS, people end up just thinking
> > > reiserfs is slow.
> > > 
> > > -chris
> > > 
> > > 
> > 
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-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord@MIT.EDU                        PGP key available