File parted-improve-loop-support.patch of Package parted
Index: parted-2.4/NEWS
===================================================================
--- parted-2.4.orig/NEWS
+++ parted-2.4/NEWS
@@ -2,6 +2,10 @@ GNU parted NEWS
* Noteworthy changes in release 2.4 (2011-05-18) [stable]
+** New features
+
+ parted has improved support for partitionable loopback devices
+
** Bug fixes
parted no longer allows the modification of certain in-use partitions.
Index: parted-2.4/include/parted/device.h
===================================================================
--- parted-2.4.orig/include/parted/device.h
+++ parted-2.4/include/parted/device.h
@@ -48,7 +48,8 @@ typedef enum {
PED_DEVICE_SDMMC = 14,
PED_DEVICE_VIRTBLK = 15,
PED_DEVICE_AOE = 16,
- PED_DEVICE_MD = 17
+ PED_DEVICE_MD = 17,
+ PED_DEVICE_LOOP = 18
} PedDeviceType;
typedef struct _PedDevice PedDevice;
Index: parted-2.4/libparted/arch/linux.c
===================================================================
--- parted-2.4.orig/libparted/arch/linux.c
+++ parted-2.4/libparted/arch/linux.c
@@ -586,7 +586,7 @@ _device_probe_type (PedDevice* dev)
} else if (_is_virtblk_major(dev_major)) {
dev->type = PED_DEVICE_VIRTBLK;
} else if (dev_major == LOOP_MAJOR) {
- dev->type = PED_DEVICE_FILE;
+ dev->type = PED_DEVICE_LOOP;
} else if (dev_major == MD_MAJOR) {
dev->type = PED_DEVICE_MD;
} else {
@@ -1376,6 +1376,11 @@ linux_new (const char* path)
goto error_free_arch_specific;
break;
+ case PED_DEVICE_LOOP:
+ if (!init_generic (dev, _("Loopback device")))
+ goto error_free_arch_specific;
+ break;
+
case PED_DEVICE_DM:
{
char* type;
@@ -2411,6 +2416,61 @@ _blkpg_remove_partition (PedDisk* disk,
BLKPG_DEL_PARTITION);
}
+/* Read the integer from /sys/block/DEV_BASE/ENTRY and set *VAL
+ to that value, where DEV_BASE is the last component of DEV->path.
+ Upon success, return true. Otherwise, return false. */
+static bool
+_sysfs_int_entry_from_dev(PedDevice const* dev, const char *entry, int *val)
+{
+ char path[128];
+ int r = snprintf(path, sizeof(path), "/sys/block/%s/%s",
+ last_component(dev->path), entry);
+ if (r < 0 || r >= sizeof(path))
+ return false;
+
+ FILE *fp = fopen(path, "r");
+ if (!fp)
+ return false;
+
+ bool ok = fscanf(fp, "%d", val) == 1;
+ fclose(fp);
+
+ return ok;
+}
+
+/* Return the maximum number of partitions that the loopback device can hold.
+ First, check the loop-module-exported max_part parameter (since linux-3.0).
+ If that is not available, fall back to checking ext_range, which seems to
+ have (for some reason) different semantics compared to other devices;
+ specifically, ext_range <= 1 means that the loopback device does
+ not support partitions. */
+static unsigned int
+_loop_get_partition_range(PedDevice const* dev)
+{
+ int max_part;
+ bool ok = false;
+
+ /* max_part module param is exported since kernel 3.0 */
+ FILE *fp = fopen("/sys/module/loop/parameters/max_part", "r");
+ if (fp) {
+ ok = fscanf(fp, "%d", &max_part) == 1;
+ fclose(fp);
+ }
+
+ if (ok)
+ return max_part > 0 ? max_part : 0;
+
+ /*
+ * max_part is not exported - check ext_range;
+ * device supports partitions if ext_range > 1
+ */
+ int range;
+ ok = _sysfs_int_entry_from_dev(dev, "range", &range);
+
+ return ok && range > 1 ? range : 0;
+}
+
+
/*
* The number of partitions that a device can have depends on the kernel.
* If we don't find this value in /sys/block/DEV/ext_range, we will use our own
@@ -2419,22 +2479,12 @@ _blkpg_remove_partition (PedDisk* disk,
static unsigned int
_device_get_partition_range(PedDevice* dev)
{
- int range, r;
- char path[128];
- FILE* fp;
- bool ok;
-
- r = snprintf(path, sizeof(path), "/sys/block/%s/ext_range",
- last_component(dev->path));
- if (r < 0 || r >= sizeof(path))
- return MAX_NUM_PARTS;
+ /* loop handling is special */
+ if (dev->type == PED_DEVICE_LOOP)
+ return _loop_get_partition_range(dev);
- fp = fopen(path, "r");
- if (!fp)
- return MAX_NUM_PARTS;
-
- ok = fscanf(fp, "%d", &range) == 1;
- fclose(fp);
+ int range;
+ bool ok = _sysfs_int_entry_from_dev(dev, "ext_range", &range);
/* (range <= 0) is none sense.*/
return ok && range > 0 ? range : MAX_NUM_PARTS;
Index: parted-2.4/parted/parted.c
===================================================================
--- parted-2.4.orig/parted/parted.c
+++ parted-2.4/parted/parted.c
@@ -1464,7 +1464,7 @@ _print_disk_info (const PedDevice *dev,
"cpqarray", "file", "ataraid", "i2o",
"ubd", "dasd", "viodasd", "sx8", "dm",
"xvd", "sd/mmc", "virtblk", "aoe",
- "md"};
+ "md", "loopback"};
char* start = ped_unit_format (dev, 0);
PedUnit default_unit = ped_unit_get_default ();
