[PATCH 2/2] Add BLKPG_GET_PARTITION operation

From: Phillip Susi
Date: Sat Dec 24 2011 - 17:21:49 EST


Add a new operation to the BLKPG ioctl to read the partition.
This allows user space to find the current start and length
of a partition without having to open the partition and use
the long depreciated HDIO_GETGEO ioctl.

Signed-off-by: Phillip Susi <psusi@xxxxxxxxxx>
---
block/ioctl.c | 15 +++++++++++++++
include/linux/blkpg.h | 1 +
2 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/block/ioctl.c b/block/ioctl.c
index 08b2bd6..fad9064 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -141,6 +141,21 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
bdput(bdevp);
disk_put_part(part);
return 0;
+ case BLKPG_GET_PARTITION:
+ mutex_lock(&bdev->bd_mutex);
+ part = disk_get_part(disk, partno);
+ if (!part)
+ {
+ mutex_unlock(&bdev->bd_mutex);
+ return -ENXIO;
+ }
+ p.start = part->start_sect << 9;
+ p.length = part->nr_sects << 9;
+ disk_put_part(part);
+ mutex_unlock(&bdev->bd_mutex);
+ if (copy_to_user(a.data, &p, sizeof(struct blkpg_partition)))
+ return -EFAULT;
+ return 0;
default:
return -EINVAL;
}
diff --git a/include/linux/blkpg.h b/include/linux/blkpg.h
index a851944..72bf5e2 100644
--- a/include/linux/blkpg.h
+++ b/include/linux/blkpg.h
@@ -41,6 +41,7 @@ struct blkpg_ioctl_arg {
#define BLKPG_ADD_PARTITION 1
#define BLKPG_DEL_PARTITION 2
#define BLKPG_RESIZE_PARTITION 3
+#define BLKPG_GET_PARTITION 4

/* Sizes of name fields. Unused at present. */
#define BLKPG_DEVNAMELTH 64
--
1.7.5.4

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