During investigation of an NFSv4 client crash reported by glebius@, jhb@ spotted that nfscl_getstateid() might modify credentials when called from nfsrpc_read() for the case where p != NULL, whereas nfsrpc_read() only did a crdup() to get new credentials for p == NULL. This bug was introduced by r195510, since pre-r195510 nfscl_getstateid() only modified credentials for the p == NULL case. This patch modifies nfsrpc_read()/nfsrpc_write() so that they do crdup() for the p != NULL case. It is conceivable that this bug caused the crash reported by glebius@, but that will not be determined for some time, since the crash occurred after about 1month of operation.
During investigation of an NFSv4 client crash reported by glebius@,
jhb@ spotted that nfscl_getstateid() might modify credentials when
called from nfsrpc_read() for the case where p != NULL, whereas
nfsrpc_read() only did a crdup() to get new credentials for p == NULL.
This bug was introduced by r195510, since pre-r195510 nfscl_getstateid()
only modified credentials for the p == NULL case. This patch modifies
nfsrpc_read()/nfsrpc_write() so that they do crdup() for the p != NULL case.
It is conceivable that this bug caused the crash reported by glebius@, but
that will not be determined for some time, since the crash occurred after
about 1month of operation.

Tested by:	glebius
Reviewed by:	jhb
MFC after:	2 weeks

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