+ if (sizealloc < tp->b_bufsize) {
+ ep = bfreelist[BQ_EMPTY].av_forw;
+ if (ep == &bfreelist[BQ_EMPTY])
+ goto out;
+ notavail(ep);
+ pagemove(tp->b_un.b_addr + sizealloc, ep->b_un.b_addr,
+ (int)tp->b_bufsize - sizealloc);
+ ep->b_bufsize = tp->b_bufsize - sizealloc;
+ tp->b_bufsize = sizealloc;
+ ep->b_flags |= B_INVAL;
+ ep->b_bcount = 0;
+ brelse(ep);
+ goto out;
+ }
+ /*
+ * More buffer space is needed. Get it out of buffers on
+ * the "most free" list, placing the empty headers on the
+ * BQ_EMPTY buffer header list.
+ */
+ while (tp->b_bufsize < sizealloc) {
+ take = sizealloc - tp->b_bufsize;
+ bp = getnewbuf();
+ if (take >= bp->b_bufsize)
+ take = bp->b_bufsize;
+ pagemove(&bp->b_un.b_addr[bp->b_bufsize - take],
+ &tp->b_un.b_addr[tp->b_bufsize], take);
+ tp->b_bufsize += take;
+ bp->b_bufsize = bp->b_bufsize - take;
+ if (bp->b_bcount > bp->b_bufsize)
+ bp->b_bcount = bp->b_bufsize;
+ if (bp->b_bufsize <= 0) {
+ bremhash(bp);
+ binshash(bp, &bfreelist[BQ_EMPTY]);
+ bp->b_dev = (dev_t)NODEV;
+ bp->b_error = 0;
+ bp->b_flags |= B_INVAL;
+ }
+ brelse(bp);
+ }
+#else
+ /*
+ * Buffer size is shrinking
+ * Just put the tail end back in the map
+ */
+ if (sizealloc < tp->b_bufsize) {
+ rmfree(buffermap, (long)(tp->b_bufsize - sizealloc),
+ (long)(tp->b_un.b_addr + sizealloc));
+ tp->b_bufsize = sizealloc;
+ goto out;
+ }
+ /*
+ * Buffer is being expanded or created
+ * If being expanded, attempt to get contiguous
+ * section, otherwise get a new chunk and copy.
+ * If no space, free up a buffer on the AGE list
+ * and try again.
+ */
+ do {
+ if ((osize = tp->b_bufsize)) {
+ a = (char *)rmget(buffermap, (long)(sizealloc-osize),
+ (long)(tp->b_un.b_addr + osize));
+ if (a == 0) {
+ a = (char *)rmalloc(buffermap, (long)sizealloc);
+ if (a != 0) {
+ bcopy(tp->b_un.b_addr, a, osize);
+ rmfree(buffermap, (long)osize,
+ (long)tp->b_un.b_addr);
+ tp->b_un.b_addr = a;
+ }
+ }
+ } else {
+ a = (char *)rmalloc(buffermap, (long)sizealloc);
+ if (a != 0)
+ tp->b_un.b_addr = a;
+ }
+ } while (a == 0 && bfreemem());
+ if (a == 0) {
+ brelse(tp);
+ return (0);
+ }
+ tp->b_bufsize = sizealloc;
+#endif
+out:
+ tp->b_bcount = size;
+ return (1);