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Re: Max Mount Count



Hi,

On Fri, Jun 08, 2001 at 10:20:52AM -0700, Jay Weber wrote:

> I'm using the same generic lockfs/unlockfs() wrapper code as supplied with
> 2.4 LVM patches for doing those bits.  I believe Andrea Arcangeli has
> included them in his 2.2 tree also for use with reiserfs.
> 
> Cut&Paste below (pretty small):
[deleted]

Looks sane.

> Yeah, I'm using the following which AFAIK seems to cover the occurances
> that LVM surfaced.  I can run multiple pvscans, etc for hours without
> generating the refile buffers at least.

I'll apply to 2.2.  For 2.4, we need to take appropriate locking
before we can make such a test.  

Andrew, what do you think?  I'm tempted to solve this by taking the
lru_list_lock and bumping b_count when adding the journal_head to an
existing buffer_head.  That would certainly protect against buffer
invalidation and try_to_free_buffers, without requiring us to
hard-code the protection of journaled buffers into the rest of the VM.

However, I'm still nervous: journaling can keep buffers around for
quite a while for various reasons.  WHY does LVM want to invalidate
buffers?  I'm scared that by "fixing" this we actually mask a deeper
problem.  By causing journaled buffers to remain in the system after
an invalidate, are we going to violate some assumption that LVM is
making about its ability to flush things from the kernel?

Cheers,
 Stephen





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