K 10 svn:author V 3 pfg K 8 svn:date V 27 2013-07-09T01:31:04.084798Z K 7 svn:log V 347 Enhancement when writing an entire block of a file. Merge from UFS r231313: This change first attempts the uiomove() to the newly allocated (and dirty) buffer and only zeros it if the uiomove() fails. The effect is to eliminate the gratuitous zeroing of the buffer in the usual case where the uiomove() successfully fills it. MFC after: 3 days END