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From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: File Truncation Philosophy
Message-ID: <1993Apr8.050452.7600@fcom.cc.utah.edu>
Sender: news@fcom.cc.utah.edu
Organization: Weber State University (Ogden, UT)
References: <1993Apr2.140809.16589@cm.cf.ac.uk>> <BLYMN.93Apr3213001@siren.awadi.com.au> <C4z32z.ExC@veda.is>
Date: Thu, 8 Apr 93 05:04:52 GMT
Lines: 35
In article <C4z32z.ExC@veda.is> adam@veda.is (Adam David) writes:
[ ... method of avoiding the problem by juggling inodes ... ]
>Have I missed anything important, or could this really work?
How about: it's not portable internally and would have to be rewritten for
each and every file system type that was (A) writable and (B) contained
executables *AND* it fixes a problem with the way the VM system handles
swapping by hacking the file system.
Seriously, the canonical method is returning an EBUSY or ETXTBSY, checking
for it in vncalls.c, and then making calls to the VM system to have swap
back the file instead of the program image in the file doing it, and then
retrying the operation (again, in vncalls.c).
This would give the advantage of quick-start without the disadvantage of
paging from the file, since the from-file store would be fixed *above* the
UFS/PCFS/XYZZYFS layer.
The intermediate soloution of returning EBUSY/ETXTBSY has a long and ignoble
history, and should be allowable; the main issue is allowing an unlink/rm
of a file while it's running, something I don't think the VTEXT soloution
allows.
Terry Lambert
terry@icarus.weber.edu
terry_lambert@novell.com
---
Any opinions in this posting are my own and not those of my present
or previous employers.
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