Function bufkva_alloc

freebsd/kern/vfs_bio.c:2026–2060

* bufkva_alloc: * * Allocate the buffer KVA and set b_kvasize and b_kvabase. */

 *	Allocate the buffer KVA and set b_kvasize and b_kvabase.
 */
static int
bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
{
	vm_offset_t addr;
	int error;

	KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
	    ("Invalid gbflags 0x%x in %s", gbflags, __func__));
	MPASS((bp->b_flags & B_MAXPHYS) == 0);
	KASSERT(maxsize <= maxbcachebuf,
	    ("bufkva_alloc kva too large %d %u", maxsize, maxbcachebuf));

	bufkva_free(bp);

	addr = 0;
	error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
	if (error != 0) {
		/*
		 * Buffer map is too fragmented.  Request the caller
		 * to defragment the map.
		 */
		return (error);
	}
	bp->b_kvabase = (caddr_t)addr;
	bp->b_kvasize = maxsize;
	counter_u64_add(bufkvaspace, bp->b_kvasize);
	if ((gbflags & GB_UNMAPPED) != 0) {
		bp->b_data = unmapped_buf;
		BUF_CHECK_UNMAPPED(bp);
	} else {
		bp->b_data = bp->b_kvabase;
		BUF_CHECK_MAPPED(bp);
	}
	return (0);
}

/*
 *	bufkva_reclaim: