partitions: add ->set_capacity block device method

* Add ->set_capacity block device method and use it in rescan_partitions()
  to attempt enabling native capacity of the device upon detecting the
  partition which exceeds device capacity.

* Add GENHD_FL_NATIVE_CAPACITY flag to try limit attempts of enabling
  native capacity during partition scan.

Together with the consecutive patch implementing ->set_capacity method in
ide-gd device driver this allows automatic disabling of Host Protected Area
(HPA) if any partitions overlapping HPA are detected.

Cc: Robert Hancock <hancockrwd@gmail.com>
Cc: Frans Pop <elendil@planet.nl>
Cc: "Andries E. Brouwer" <Andries.Brouwer@cwi.nl>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Emphatically-Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

3 files changed, 35 insertions, 11 deletions

diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 137a708bb215..4bc2c43fa083 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -546,28 +546,49 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
 
         /* add partitions */
         for (p = 1; p < state->limit; p++) {
-                sector_t size = state->parts[p].size;
-                sector_t from = state->parts[p].from;
+                sector_t size, from;
+try_scan:
+                size = state->parts[p].size;
                 if (!size)
                         continue;
+
+                from = state->parts[p].from;
                 if (from >= get_capacity(disk)) {
                         printk(KERN_WARNING
                                "%s: p%d ignored, start %llu is behind the end of the disk\n",
                                disk->disk_name, p, (unsigned long long) from);
                         continue;
                 }
+
                 if (from + size > get_capacity(disk)) {
-                        /*
-                         * we can not ignore partitions of broken tables
-                         * created by for example camera firmware, but we
-                         * limit them to the end of the disk to avoid
-                         * creating invalid block devices
-                         */
+                        struct block_device_operations *bdops = disk->fops;
+                        unsigned long long capacity;
+
                         printk(KERN_WARNING
-                               "%s: p%d size %llu exceeds device capacity, "
-                               "limited to end of disk\n",
+                               "%s: p%d size %llu exceeds device capacity, ",
                                disk->disk_name, p, (unsigned long long) size);
-                        size = get_capacity(disk) - from;
+
+                        if (bdops->set_capacity &&
+                            (disk->flags & GENHD_FL_NATIVE_CAPACITY) == 0) {
+                                printk(KERN_CONT "enabling native capacity\n");
+                                capacity = bdops->set_capacity(disk, ~0ULL);
+                                disk->flags |= GENHD_FL_NATIVE_CAPACITY;
+                                if (capacity > get_capacity(disk)) {
+                                        set_capacity(disk, capacity);
+                                        check_disk_size_change(disk, bdev);
+                                        bdev->bd_invalidated = 0;
+                                }
+                                goto try_scan;
+                        } else {
+                                /*
+                                 * we can not ignore partitions of broken tables
+                                 * created by for example camera firmware, but
+                                 * we limit them to the end of the disk to avoid
+                                 * creating invalid block devices
+                                 */
+                                printk(KERN_CONT "limited to end of disk\n");
+                                size = get_capacity(disk) - from;
+                        }
                 }
                 part = add_partition(disk, p, from, size,
                                      state->parts[p].flags);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6f841fb1be30..a2d7298be351 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1106,6 +1106,8 @@ struct block_device_operations {
         int (*direct_access) (struct block_device *, sector_t,
                                                 void **, unsigned long *);
         int (*media_changed) (struct gendisk *);
+        unsigned long long (*set_capacity) (struct gendisk *,
+                                                unsigned long long);
         int (*revalidate_disk) (struct gendisk *);
         int (*getgeo)(struct block_device *, struct hd_geometry *);
         struct module *owner;
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 634c53028fb8..239e24b081a9 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -113,6 +113,7 @@ struct hd_struct {
 #define GENHD_FL_UP                             16
 #define GENHD_FL_SUPPRESS_PARTITION_INFO        32
 #define GENHD_FL_EXT_DEVT                       64 /* allow extended devt */
+#define GENHD_FL_NATIVE_CAPACITY                128
 
 #define BLK_SCSI_MAX_CMDS       (256)
 #define BLK_SCSI_CMD_PER_LONG   (BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))