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Re: [Cluster-devel] [PATCH 0 of 5]Bz #248176: GFS2: invalid metadata block, gfs2_meta_indirect_buffer



Hi,

None of these patches apply due to whitespace breakage.

On Tue, 2007-07-24 at 00:07 -0500, Bob Peterson wrote:
> Here is a set of five patches designed to fix the "invalid metadata
> block" and hang problems encountered when running the revolver test.
> 
> In order, the five patches are:
> 
> 1. There were still some critical variables being manipulated outside
>    the log_lock spinlock.  That usually resulted in more hangs.
The BUG_ON(!buffer_mapped()) line in this patch can be removed as its
only debugging.

> 2. The list_move code previously concocted in log.c for bug #238162
>    (see https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=238162#c23)
>    seems to be causing a problem.  That section was reverted.  HOWEVER,
>    I need to rerun the test cases listed in that bug to make sure
>    removing it doesn't cause anything to break.  I haven't had time yet.
Moving the assignment head = &sdp->sd_ail1_list; doesn't give us
anything since head is a pointer and will be constant whether we have
the lock or not.

> 3. The try_rgrp_unlink code in rgrp.c had an infinite loop.  This was
>    caused because the bitmap function rgblk_search can return a block
>    less than the "goal" block, in which case it was looping.  The fix is
>    to make it always march forward as needed.
Ok.

> 4. There was metadata corruption caused because the clone bitmaps weren't
>    being kept in synch with the regular bitmaps in some cases.
>    Code was added to keep them in synch.
I need to look at this in more detail. You might be right, but its worth
being rather careful in this part of the code.

> 5. Metadata corruption was occurring because page references weren't
>    being removed in all cases.  I previously added a function called
>    detach_bufdata, but I discovered there already WAS a function out
>    there to do the job.  It's called gfs2_meta_cache_flush.  So I added
>    a call to that to remove the page references.
>    Recently I had been thinking that this was entirely unnecessary, but
>    when I removed the code, the metadata corruption problem returned
>    immediately.  It might be that there is a timing window where the
>    pages can be referenced before gfs2_meta_cache_flush is called and
>    my patch cleans them up sooner.
Yes, this looks good,

Steve.



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