For some setups (multipath or dmraid) the in-kernel partition scan
is pointless as the (block) partitions won't be used anywhere.
Worse, it might trigger I/O errors as the partition table might not
be accessible (eg for the passive path of a multipath device) or
even invalid (eg for RAID0 dmraid).
This patch allows to switch off the in-kernel partition scan by adding
'no_partition_scan' to the kernel commandline. Partitions scan can be
allowed for individual disk by echoing a positive number into
/sys/block/XXX/range and rescan the disk.
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
---
Documentation/kernel-parameters.txt | 5 ++++
block/genhd.c | 41 ++++++++++++++++++++++++++++++++--
2 files changed, 43 insertions(+), 3 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index d08759a..47bed29 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1424,6 +1424,11 @@ and is between 256 and 4096 characters. It is defined in the file
mtdparts= [MTD]
See drivers/mtd/cmdlinepart.c.
+ no_partition_scan [KNL] Inhibit in-kernel partition scan
+ for all block devices. Partition scan can be
+ re-enabled for individual devices by writing
+ a non-zero value in /sys/block/XX/range.
+
onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
diff --git a/block/genhd.c b/block/genhd.c
index f4c64c2..d120ec8 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -504,6 +504,18 @@ static int exact_lock(dev_t devt, void *data)
return 0;
}
+static int __read_mostly no_partition_scan;
+
+static int __init no_partition_scan_setup(char *str)
+{
+ no_partition_scan = 1;
+ printk(KERN_INFO "genhd: omit partition scan.\n");
+
+ return 1;
+}
+
+__setup("no_partition_scan", no_partition_scan_setup);
+
/**
* add_disk - add partitioning information to kernel list
* @disk: per-device partitioning information
@@ -527,6 +539,8 @@ void add_disk(struct gendisk *disk)
WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
disk->flags |= GENHD_FL_UP;
+ if (no_partition_scan)
+ disk->flags |= GENHD_FL_USERSPACE_PARTITIONS;
retval = blk_alloc_devt(&disk->part0, &devt);
if (retval) {
@@ -816,7 +830,27 @@ static ssize_t disk_range_show(struct device *dev,
{
struct gendisk *disk = dev_to_disk(dev);
- return sprintf(buf, "%d\n", disk->minors);
+ return sprintf(buf, "%d\n",
+ (disk_userspace_partitions(disk) ? 0 : disk->minors));
+}
+
+static ssize_t disk_range_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ int i;
+
+ if (count > 0 && sscanf(buf, "%d", &i) > 0) {
+ if (i == 0)
+ disk->flags |= GENHD_FL_USERSPACE_PARTITIONS;
+ else if (i <= disk->minors)
+ disk->flags &= ~GENHD_FL_USERSPACE_PARTITIONS;
+ else
+ count = -EINVAL;
+ }
+
+ return count;
}
static ssize_t disk_ext_range_show(struct device *dev,
@@ -824,7 +858,8 @@ static ssize_t disk_ext_range_show(struct device *dev,
{
struct gendisk *disk = dev_to_disk(dev);
- return sprintf(buf, "%d\n", disk_max_parts(disk));
+ return sprintf(buf, "%d\n",
+ disk_userspace_partitions(disk) ? 0: disk_max_parts(disk));
}
static ssize_t disk_removable_show(struct device *dev,
@@ -861,7 +896,7 @@ static ssize_t disk_alignment_offset_show(struct device *dev,
return sprintf(buf, "%d\n", queue_alignment_offset(disk->queue));
}
-static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
+static DEVICE_ATTR(range, S_IRUGO, disk_range_show, disk_range_store);
static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
--
1.5.3.2
--
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