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-rw-r--r--drivers/block/loop.c30
-rw-r--r--include/linux/loop.h1
2 files changed, 31 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 2621ed2ce6d2..40b17d3b55a1 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1192,6 +1192,30 @@ loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
return err;
}
+static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
+{
+ int err;
+ sector_t sec;
+ loff_t sz;
+
+ err = -ENXIO;
+ if (unlikely(lo->lo_state != Lo_bound))
+ goto out;
+ err = figure_loop_size(lo);
+ if (unlikely(err))
+ goto out;
+ sec = get_capacity(lo->lo_disk);
+ /* the width of sector_t may be narrow for bit-shift */
+ sz = sec;
+ sz <<= 9;
+ mutex_lock(&bdev->bd_mutex);
+ bd_set_size(bdev, sz);
+ mutex_unlock(&bdev->bd_mutex);
+
+ out:
+ return err;
+}
+
static int lo_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
@@ -1224,6 +1248,11 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
case LOOP_GET_STATUS64:
err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
break;
+ case LOOP_SET_CAPACITY:
+ err = -EPERM;
+ if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
+ err = loop_set_capacity(lo, bdev);
+ break;
default:
err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
}
@@ -1371,6 +1400,7 @@ static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
lo, (struct compat_loop_info __user *) arg);
mutex_unlock(&lo->lo_ctl_mutex);
break;
+ case LOOP_SET_CAPACITY:
case LOOP_CLR_FD:
case LOOP_GET_STATUS64:
case LOOP_SET_STATUS64:
diff --git a/include/linux/loop.h b/include/linux/loop.h
index 6ffd6db5bb0d..40725447f5e0 100644
--- a/include/linux/loop.h
+++ b/include/linux/loop.h
@@ -160,5 +160,6 @@ int loop_unregister_transfer(int number);
#define LOOP_SET_STATUS64 0x4C04
#define LOOP_GET_STATUS64 0x4C05
#define LOOP_CHANGE_FD 0x4C06
+#define LOOP_SET_CAPACITY 0x4C07
#endif