Date: Tue, 12 Feb 2002 23:53:23 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Bruce Evans <bde@zeta.org.au> Cc: Matteo <drummino@yahoo.com>, <freebsd-stable@FreeBSD.ORG>, <freebsd-bugs@FreeBSD.ORG>, <aiuto@gufi.org> Subject: Re: Crash System with MSDOS file-system driver! Message-ID: <200202130753.g1D7rNw97615@apollo.backplane.com> References: <20020213180814.R6948-100000@gamplex.bde.org>
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:> (and, in anycase, also non-VMIO).
:>
:> The buffer cache API supports short reads. It is not a bug or a mistake.
:
:I disagree. Critical callers like ffs_balloc() never checked for short
:reads, so it must be bread()'s responsibility not to return them.
:
:Bruce
Nonsense. Critical callers like ffs_balloc() do not have to check
for short reads because they never call block functions using out of
bounds offsets. This does not in any way imply that we should remove
the feature from our general purpose buffer cache. UFS and MSDOSFS
are not the only modules that use the buffer cache.
The only real bug here is that a number of modules, including UFS,
MSDOSFS, and NFS, incorrectly assume that b_resid is a persistent
field rather then transitory field valid only at completion of an I/O.
-Matt
Matthew Dillon
<dillon@backplane.com>
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