Alasdair G Kergon wrote:
> On Wed, Jul 08, 2009 at 02:14:50PM +0530, Nikanth Karthikesan wrote:
>
>> From: Hannes Reinecke <hare@xxxxxxx>
>> Subject: Emulate BLKRRPART on device-mapper
>>
>> Partitions on device-mapper devices are managed by kpartx (if at
>> all). So if we were just to send out a 'change' event if someone
>> called BLKRRPART on these devices, kpartx will be triggered via udev
>> and can manage the partitions accordingly.
>>
>>
> Please could I have a 'Tested-by' for this one?
>
I am afraid that this patch cannot work, BLRRPART never reach this code.
I tried another idea - or is there better way how to achieve that?
Milan
---
From: Milan Broz <mbroz@xxxxxxxxxx>
Add genhd flag requesting notification of partition changes only.
This patch provides notification mechanism which allows handle partition
code in userspace.
If the BLKRRPART ioctl arrives and GENHD_FL_PARTITION_CHANGE_NOTIFY
is set, just send uevent and ignore in-kernel partitioning code.
This is useful e.g. for device-mapper devices, which can use kpartx
or similar tool in udev rules.
Signed-off-by: Milan Broz <mbroz@xxxxxxxxxx>
---
block/ioctl.c | 3 ++-
drivers/md/dm.c | 1 +
fs/partitions/check.c | 6 ++++++
include/linux/genhd.h | 8 ++++++++
4 files changed, 17 insertions(+), 1 deletions(-)
diff --git a/block/ioctl.c b/block/ioctl.c
index 500e4c7..bce793f 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -101,7 +101,8 @@ static int blkdev_reread_part(struct block_device *bdev)
struct gendisk *disk = bdev->bd_disk;
int res;
- if (!disk_partitionable(disk) || bdev != bdev->bd_contains)
+ if (!disk_userspace_partitions(disk) &&
+ (!disk_partitionable(disk) || bdev != bdev->bd_contains))
return -EINVAL;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 9acd54a..1186ce1 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1791,6 +1791,7 @@ static struct mapped_device *alloc_dev(int minor)
md->disk->queue = md->queue;
md->disk->private_data = md;
sprintf(md->disk->disk_name, "dm-%d", minor);
+ md->disk->flags |= GENHD_FL_PARTITION_CHANGE_NOTIFY;
add_disk(md->disk);
format_dev_t(md->name, MKDEV(_major, minor));
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index ea4e6cb..bb42c44 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -521,6 +521,12 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
struct parsed_partitions *state;
int p, highest, res;
+ /* partitions handled in userspace, just send change event */
+ if (disk_userspace_partitions(disk)) {
+ kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
+ return 0;
+ }
+
if (bdev->bd_part_count)
return -EBUSY;
res = invalidate_partition(disk, 0);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 45fc320..a241bd6 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -116,6 +116,9 @@ struct hd_struct {
#define GENHD_FL_EXT_DEVT 64 /* allow extended devt */
#define GENHD_FL_NATIVE_CAPACITY 128
+/* notify udev instead of use in-kernel partitioning */
+#define GENHD_FL_PARTITION_CHANGE_NOTIFY 256
+
#define BLK_SCSI_MAX_CMDS (256)
#define BLK_SCSI_CMD_PER_LONG (BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))
@@ -180,6 +183,11 @@ static inline struct gendisk *part_to_disk(struct hd_struct *part)
return NULL;
}
+static inline bool disk_userspace_partitions(struct gendisk *disk)
+{
+ return (disk->flags & GENHD_FL_PARTITION_CHANGE_NOTIFY) ? 1 : 0;
+}
+
static inline int disk_max_parts(struct gendisk *disk)
{
if (disk->flags & GENHD_FL_EXT_DEVT)
--
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