Rename header_offset and header_interval options

Header doesn't really express that this has to do with io verification.
So rename the options to verify_offset and verify_interval.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/HOWTO b/HOWTO
index 8cb849c..2fbbc1d 100644
--- a/HOWTO
+++ b/HOWTO
@@ -603,11 +603,11 @@
 		fast IO where the red-black tree sorting CPU time becomes
 		significant.
 
-header_offset=siint	Swap the verification header with data somewhere else
+verify_offset=siint	Swap the verification header with data somewhere else
 			in the block before writing. Its swapped back before
 			verifying.
 
-header_interval=siint	Write the verification header at a finer granularity
+verify_interval=siint	Write the verification header at a finer granularity
 			than the blocksize. It will be written for chunks the
 			size of header_interval. blocksize should divide this
 			evenly.
diff --git a/fio.h b/fio.h
index e97caf1..eb36d1c 100644
--- a/fio.h
+++ b/fio.h
@@ -395,8 +395,8 @@
 	unsigned int sync_io;
 	unsigned int verify;
 	unsigned int verifysort;
-	unsigned int header_interval;
-	unsigned int header_offset;
+	unsigned int verify_interval;
+	unsigned int verify_offset;
 	unsigned int use_thread;
 	unsigned int unlink;
 	unsigned int do_disk_util;
diff --git a/options.c b/options.c
index 01d2386..5a63f63 100644
--- a/options.c
+++ b/options.c
@@ -203,14 +203,16 @@
 	return add_dir_files(td, td->o.opendir);
 }
 
-static int str_header_offset_cb(void *data, unsigned int *off)
+static int str_verify_offset_cb(void *data, unsigned int *off)
 {
 	struct thread_data *td = data;
+
 	if (*off && *off < sizeof(struct verify_header)) {
-		log_err("fio: header_offset too small\n");
+		log_err("fio: verify_offset too small\n");
 		return 1;
 	}
-	td->o.header_offset = *off;
+
+	td->o.verify_offset = *off;
 	return 0;
 }
 
@@ -615,18 +617,18 @@
 		.def	= "1",
 	},
 	{
-		.name   = "header_interval",
+		.name   = "verify_interval",
 		.type   = FIO_OPT_STR_VAL_INT,
-		.off1   = td_var_offset(header_interval),
+		.off1   = td_var_offset(verify_interval),
 		.minval	= 2 * sizeof(struct verify_header),
-		.help   = "Store buffer header every N bytes",
+		.help   = "Store verify buffer header every N bytes",
 	},
 	{
-		.name	= "header_offset",
+		.name	= "verify_offset",
 		.type	= FIO_OPT_STR_VAL_INT,
-		.help	= "Offset header location by N bytes",
+		.help	= "Offset verify header location by N bytes",
 		.def	= "0",
-		.cb	= str_header_offset_cb,	
+		.cb	= str_verify_offset_cb,	
 	},
 	{
 		.name	= "write_iolog",
diff --git a/verify.c b/verify.c
index 6972fe3..d98dfcf 100644
--- a/verify.c
+++ b/verify.c
@@ -171,12 +171,12 @@
 		return 0;
 
 	hdr_inc = io_u->buflen;
-	if (td->o.header_interval)
-		hdr_inc = td->o.header_interval;
+	if (td->o.verify_interval)
+		hdr_inc = td->o.verify_interval;
 
 	for (p = io_u->buf; p < io_u->buf + io_u->buflen; p += hdr_inc) {
-		if (td->o.header_offset)
-			memswp(p, p + td->o.header_offset, sizeof(*hdr));
+		if (td->o.verify_offset)
+			memswp(p, p + td->o.verify_offset, sizeof(*hdr));
 
 		hdr = p;
 
@@ -257,8 +257,8 @@
 	fill_random_bytes(td, p, io_u->buflen);
 
 	hdr_inc = io_u->buflen;
-	if (td->o.header_interval)
-		hdr_inc = td->o.header_interval;
+	if (td->o.verify_interval)
+		hdr_inc = td->o.verify_interval;
 	data_len = hdr_inc - sizeof(*hdr);
 
 	for (;p < io_u->buf + io_u->buflen; p += hdr_inc) {
@@ -289,8 +289,8 @@
 			log_err("fio: bad verify type: %d\n", td->o.verify);
 			assert(0);
 		}
-		if (td->o.header_offset)
-			memswp(p, p + td->o.header_offset, sizeof(*hdr));
+		if (td->o.verify_offset)
+			memswp(p, p + td->o.verify_offset, sizeof(*hdr));
 	}
 }