Linux 6.5 compat: Use copy_splice_read instead of filemap_splice_read

Using the filemap_splice_read function for the splice_read handler was
leading to occasional data corruption under certain circumstances. Favor
using copy_splice_read instead, which does not demonstrate the same
erroneous behavior under the tested failure cases.

Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes #15164

module/os/linux/zfs/zpl_file.c

@@ -1142,8 +1142,8 @@ const struct file_operations zpl_file_operations = {
 	.read_iter	= zpl_iter_read,
 	.write_iter	= zpl_iter_write,
 #ifdef HAVE_VFS_IOV_ITER
-#ifdef HAVE_FILEMAP_SPLICE_READ
-	.splice_read	= filemap_splice_read,
+#ifdef HAVE_COPY_SPLICE_READ
+	.splice_read	= copy_splice_read,
 #else
 	.splice_read	= generic_file_splice_read,
 #endif