Re: Status of buffered write path (deadlock fixes)

From: Nick Piggin
Date: Mon Dec 11 2006 - 09:22:09 EST


Nick Piggin wrote:
Mark Fasheh wrote:

If we make the change I described above (looking for BH_New buffers outside
the range passed), then zero length or partial shouldn't matter, but zero
length instead of partial would be nicer imho just for the sake of reducing
the total number of cases down to the entire range or zero length.


We don't want to do zero length, because we might make the theoretical
livelock much easier to hit (eg. in the case of many small iovecs). But
yes we can restrict ourselves to zero-length or full-length.

On second thoughts, I think I'm wrong about that.

Consider the last page of a file, which is uptodate. A full length
commit, which extends the file, will expose transient zeroes if the
usercopy fails.

--
SUSE Labs, Novell Inc.
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