83 	struct buf *b_back;		/*  "  */  member
139 	struct buf *b_forw, *b_back;	/* queue of unit queues */  member
213 	ASSERT((bp)->b_back != NULL); \
214 	(bp)->b_back->b_forw = (bp)->b_forw; \
215 	(bp)->b_forw->b_back = (bp)->b_back; \
216 	(bp)->b_forw = (bp)->b_back = NULL; \
220 	ASSERT((bp)->b_back == NULL); \
222 	ASSERT((dp)->b_back != NULL); \
224 	(bp)->b_back = (dp); \
225 	(dp)->b_forw->b_back = (bp); \
254 	struct	buf	*b_back;	/* hash list back pointer */  member
271 	struct	buf	*b_back;	/* not used */  member