Date: Wed, 6 Mar 2002 11:53:08 -0800 (PST) From: Matt Dillon <dillon@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/ufs/ufs ufs_readwrite.c Message-ID: <200203061953.g26Jr8w94263@freefall.freebsd.org>
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dillon 2002/03/06 11:53:08 PST
Modified files: (Branch: RELENG_4)
sys/ufs/ufs ufs_readwrite.c
Log:
MFC b_resid KASSERT from 1.85. This is a safety check to make sure
that b_resid is the expected 0 value in preparation for a future commit
that will remove the b_resid calculation entirely. It turns out that
b_resid WILL always be 0 except for the case where a write fails. But
in the write failure case the buffer is still valid for reading and
we still want to treat it as such (as if b_resid were 0, even though it
isn't). The filesystem code should not use b_resid in any calculations
except those involving short-read situations, and even then b_resid
will not be persistent for a VMIO backed buffer since the buffer may be
destroyed and later reconstituted, resetting b_resid to 0. short-reads
are not used by most filesystems. They are used by NFS only when reading
softlinks (using a non VMIO buffer). Joy.
Revision Changes Path
1.65.2.10 +6 -0 src/sys/ufs/ufs/ufs_readwrite.c
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