Use is_vmalloc_addr() in vdev_disk.c

The initial port of ZFS to Linux required a way to identify virtual
memory to make IO to virtual memory backed slabs work, so kmem_virt()
was created. Linux 2.6.25 introduced is_vmalloc_addr(), which is
logically equivalent to kmem_virt(). Support for kernels before 2.6.26
was later dropped and more recently, support for kernels before Linux
2.6.32 has been dropped. We retire kmem_virt() in favor of
is_vmalloc_addr() to cleanup the code.

Signed-off-by: Brian Behlendorf <[email protected]>

module/zfs/vdev_disk.c

@@ -479,7 +479,7 @@ bio_map(struct bio *bio, void *bio_ptr, unsigned int bio_size)
 		if (size > bio_size)
 			size = bio_size;
 
-		if (kmem_virt(bio_ptr))
+		if (is_vmalloc_addr(bio_ptr))
 			page = vmalloc_to_page(bio_ptr);
 		else
 			page = virt_to_page(bio_ptr);