From: Karel Zak <kzak@redhat.com>
Date: Fri, 19 Mar 2010 14:56:27 +0000 (+0100)
Subject: fdisk: fix -b <sectorsize>
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eb406c0e66cdeffa239c23b09d73ac73d5d643de;p=util-linux

fdisk: fix -b <sectorsize>

The old fdisk (<2.17) does not differentiate between logical and
physical sector size, it uses the <sectorsize> for everything.

Now, we have logical and physical sectors size, but the -b option
changes the logical size only. The second bug is that "fdisk -b <sz>"
does not read topology information (it means that all I/O limits and
physical sector size are 512 (default).

The backwardly compatible bug fix is to override both sizes, logical
and physical if "-b" is used.

In future we can add a special option for physical size only.

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/fdisk/fdisk.8 b/fdisk/fdisk.8
index 367837d9..30dc9678 100644
--- a/fdisk/fdisk.8
+++ b/fdisk/fdisk.8
@@ -182,7 +182,9 @@ program and Linux partitions with the Linux fdisk or Linux cfdisk program.
 .BI "\-b " sectorsize
 Specify the sector size of the disk. Valid values are 512, 1024, 2048 or 4096.
 (Recent kernels know the sector size. Use this only on old kernels or
-to override the kernel's ideas.)
+to override the kernel's ideas.) Since util-linux-ng 2.17 fdisk differentiates
+between logical and physical sector size. This option changes both sector sizes to
+.IB sectorsize .
 .TP
 .BI \-h
 Print help and then exit.
diff --git a/fdisk/fdisk.c b/fdisk/fdisk.c
index 09efd1cc..1d7196e3 100644
--- a/fdisk/fdisk.c
+++ b/fdisk/fdisk.c
@@ -965,8 +965,6 @@ get_topology(int fd) {
 #ifdef HAVE_LIBBLKID_INTERNAL
 	blkid_probe pr;
 
-	if (user_set_sector_size)
-		return;
 	pr = blkid_new_probe();
 	if (pr && blkid_probe_set_device(pr, fd, 0, 0) == 0) {
 		blkid_topology tp = blkid_probe_get_topology(pr);
@@ -995,12 +993,20 @@ get_topology(int fd) {
 #endif
 
 	if (user_set_sector_size)
-		;
-	else if (blkdev_get_sector_size(fd, &arg) == 0)
+		/* fdisk since 2.17 differentiate between logical and physical
+		 * sectors size. For backward compatibility the
+		 *    fdisk -b <sectorsize>
+		 * changes both, logical and physical sector size.
+		 */
+		phy_sector_size = sector_size;
+
+	else if (blkdev_get_sector_size(fd, &arg) == 0) {
 		sector_size = arg;
 
-	if (!phy_sector_size)
-		phy_sector_size = sector_size;
+		if (!phy_sector_size)
+			phy_sector_size = sector_size;
+	}
+
 	if (!min_io_size)
 		min_io_size = phy_sector_size;
 	if (!io_size)