[PATCH] dm store geometry

Allow drive geometry to be stored with a new DM_DEV_SET_GEOMETRY ioctl.
Device-mapper will now respond to HDIO_GETGEO.  If the geometry information is
not available, zero will be returned for all of the parameters.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b99df48cffed..973e63d530ae 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -17,6 +17,7 @@
 #include <linux/mempool.h>
 #include <linux/slab.h>
 #include <linux/idr.h>
+#include <linux/hdreg.h>
 #include <linux/blktrace_api.h>
 
 static const char *_name = DM_NAME;
@@ -102,6 +103,9 @@ struct mapped_device {
          */
         struct super_block *frozen_sb;
         struct block_device *suspended_bdev;
+
+        /* forced geometry settings */
+        struct hd_geometry geometry;
 };
 
 #define MIN_IOS 256
@@ -227,6 +231,13 @@ static int dm_blk_close(struct inode *inode, struct file *file)
         return 0;
 }
 
+static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
+{
+        struct mapped_device *md = bdev->bd_disk->private_data;
+
+        return dm_get_geometry(md, geo);
+}
+
 static inline struct dm_io *alloc_io(struct mapped_device *md)
 {
         return mempool_alloc(md->io_pool, GFP_NOIO);
@@ -313,6 +324,33 @@ struct dm_table *dm_get_table(struct mapped_device *md)
         return t;
 }
 
+/*
+ * Get the geometry associated with a dm device
+ */
+int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo)
+{
+        *geo = md->geometry;
+
+        return 0;
+}
+
+/*
+ * Set the geometry of a device.
+ */
+int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo)
+{
+        sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors;
+
+        if (geo->start > sz) {
+                DMWARN("Start sector is beyond the geometry limits.");
+                return -EINVAL;
+        }
+
+        md->geometry = *geo;
+
+        return 0;
+}
+
 /*-----------------------------------------------------------------
  * CRUD START:
  *   A more elegant soln is in the works that uses the queue
@@ -906,6 +944,13 @@ static int __bind(struct mapped_device *md, struct dm_table *t)
         sector_t size;
 
         size = dm_table_get_size(t);
+
+        /*
+         * Wipe any geometry if the size of the table changed.
+         */
+        if (size != get_capacity(md->disk))
+                memset(&md->geometry, 0, sizeof(md->geometry));
+
         __set_size(md, size);
         if (size == 0)
                 return 0;
@@ -1261,6 +1306,7 @@ int dm_suspended(struct mapped_device *md)
 static struct block_device_operations dm_blk_dops = {
         .open = dm_blk_open,
         .release = dm_blk_close,
+        .getgeo = dm_blk_getgeo,
         .owner = THIS_MODULE
 };