struct buf { int b_flags; struct buf *b_forw; struct buf *b_back; struct buf *av_forw; struct buf *av_back; int b_dev; int b_wcount; char *b_addr; char *b_blkno; } buf[NBUF]; /* * forw and back are shared with "buf" struct. */ struct devtab { char d_active; char d_errcnt; struct buf *b_forw; struct buf *b_back; struct buf *d_actf; struct buf *d_actl; } devtab[NMAJ]; struct buf bfreelist; #define B_READ 01 #define B_DONE 02 #define B_ERROR 04 #define B_BUSY 010 #define B_XMEM 060 #define B_WANTED 0100 #define B_RELOC 0200 #define B_ASYNC 0400 #define B_DELWRI 01000