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Date: Thu, 24 Sep 1998 14:37:15 -0400 (EDT)
From: Luoqi Chen <luoqi@watermarkgroup.com>
Message-Id: <199809241837.OAA26496@lor.watermarkgroup.com>
To: committers@FreeBSD.ORG, dillon@backplane.com
Subject: Re: Having some serious file write / mmap inconsistancy problems
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>     I've done some more tracing, but it's almost black magic.  Can someone
>     explain this?
> 
> 	* bdwrite() sets B_DELWRI in the bp, but then it goes off and calls
> 	  vfs_clean_pages() on the underlying pages.
> 
> 	* There are a number of situations where the pages can be disassociated
> 	  from the bp.  vm_hold_free_pages() will disassociate the pages,
> 	  allocbuf() may disassociate pages, and vfs_vmio_release() will 
> 	  disassociate the pages.  All of these can occur in situations where
> 	  B_DELWRI is completely ignored.
> 
It is very serious if these could ever happen. Could you add some printf
statements at the beginning of these functions to check if the B_DELWRI
flag is set for the buffer?

-lq