default to 1MiB alignment when possible

Change the linux_get_optimum_alignment() function to prefer
aligning partitions to PED_DEFAULT_ALIGNMENT (1MiB), if possible.
This helps tools like anaconda better support 4k sector drives.

* include/parted/parted.h (PED_DEFAULT_ALIGNMENT): Define.
* libparted/arch/linux.c (linux_get_optimum_alignment): Adjust.
See comments for details.
* libparted/device.c (ped_device_get_optimum_alignment): Use
PED_DEFAULT_ALIGNMENT rather than hard-coded 1048576.
* tests/t9020-alignment.sh: Adjust expectations to match new behavior.
See http://bugzilla.redhat.com/618255 for details.

diff --git a/include/parted/parted.h b/include/parted/parted.h
index b2bd2e0..a56d6a5 100644 (file)
--- a/include/parted/parted.h
+++ b/include/parted/parted.h
@@ -20,6 +20,8 @@
 #ifndef PARTED_H_INCLUDED
 #define PARTED_H_INCLUDED
 
+#define PED_DEFAULT_ALIGNMENT (1024 * 1024)
+
 #ifdef __cplusplus
 extern "C" {
 #endif

diff --git a/libparted/arch/linux.c b/libparted/arch/linux.c
index 4e61bfe..0288a15 100644 (file)
--- a/libparted/arch/linux.c
+++ b/libparted/arch/linux.c
@@ -2865,13 +2865,29 @@ linux_get_optimum_alignment(const PedDevice *dev)
         if (!tp)
                 return NULL;
 
-        /* If optimal_io_size is 0 _and_ alignment_offset is 0 _and_
-           minimum_io_size is a power of 2 then go with the device.c default */
-        unsigned long minimum_io_size = blkid_topology_get_minimum_io_size(tp);
-        if (blkid_topology_get_optimal_io_size(tp) == 0 &&
-            blkid_topology_get_alignment_offset(tp) == 0 &&
-            (minimum_io_size & (minimum_io_size - 1)) == 0)
-                return NULL;
+        /* When PED_DEFAULT_ALIGNMENT is divisible by the *_io_size or
+          there are no *_io_size values, use the PED_DEFAULT_ALIGNMENT
+           If one or the other will not divide evenly, fall through to
+           previous logic. */
+        unsigned long optimal_io = blkid_topology_get_optimal_io_size(tp);
+        unsigned long minimum_io = blkid_topology_get_minimum_io_size(tp);
+        if (
+            (!optimal_io && !minimum_io)
+           || (optimal_io && PED_DEFAULT_ALIGNMENT % optimal_io == 0
+               && minimum_io && PED_DEFAULT_ALIGNMENT % minimum_io == 0)
+           || (!minimum_io && optimal_io
+               && PED_DEFAULT_ALIGNMENT % optimal_io == 0)
+           || (!optimal_io && minimum_io
+               && PED_DEFAULT_ALIGNMENT % minimum_io == 0)
+           ) {
+            /* DASD needs to use minimum alignment */
+            if (dev->type == PED_DEVICE_DASD)
+                return linux_get_minimum_alignment(dev);
+
+            return ped_alignment_new(
+                    blkid_topology_get_alignment_offset(tp) / dev->sector_size,
+                    PED_DEFAULT_ALIGNMENT / dev->sector_size);
+        }
 
         /* If optimal_io_size is 0 and we don't meet the other criteria
            for using the device.c default, return the minimum alignment. */

diff --git a/libparted/device.c b/libparted/device.c
index 4c43e09..6cbfaaf 100644 (file)
--- a/libparted/device.c
+++ b/libparted/device.c
@@ -1,6 +1,6 @@
 /*
     libparted - a library for manipulating disk partitions
-    Copyright (C) 1999 - 2001, 2005, 2007-2009 Free Software Foundation, Inc.
+    Copyright (C) 1999 - 2001, 2005, 2007-2010 Free Software Foundation, Inc.
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -554,7 +554,8 @@ ped_device_get_optimum_alignment(const PedDevice *dev)
                 default:
                         /* Align to a grain of 1MiB (like vista / win7) */
                         align = ped_alignment_new(0,
-                                                  1048576 / dev->sector_size);
+                                                  (PED_DEFAULT_ALIGNMENT
+                                                  / dev->sector_size));
                 }
         }
 

diff --git a/tests/t9020-alignment.sh b/tests/t9020-alignment.sh
index 0d9a6c4..a16d052 100755 (executable)
--- a/tests/t9020-alignment.sh
+++ b/tests/t9020-alignment.sh
@@ -26,7 +26,7 @@ grep '^#define USE_BLKID 1' "$CONFIG_HEADER" > /dev/null ||
 
 cat <<EOF > exp || framework_failure
 minimum: 7 8
-optimal: 7 64
+optimal: 7 2048
 partition alignment: 0 1
 EOF