Loop device driver sometimes fails to impose the size limit on the
device. Keep issuing following two commands:
losetup --offset 7517244416 --sizelimit 3224971264 /dev/loop0 backed_file
blockdev --getsize64 /dev/loop0
blockdev reports file size instead of sizelimit several out of 100 times.
The problems are:
- losetup set up the device in two ioctl:
LOOP_SET_FD and LOOP_SET_STATUS64.
- LOOP_SET_STATUS64 only update size of gendisk.
Block device size will be updated lazily when device comes to use. If udev
rushes in between the two ioctl, it will bring in a block device whose
size is backing file size. If the device is not released after
LOOP_SET_STATUS64 ioctl, blockdev will not see the updated size.
Update block size in LOOP_SET_STATUS64 ioctl.
Reported-by: M. Hindess <hinde...@uk.ibm.com>
Signed-off-by: Guo Chao <y...@linux.vnet.ibm.com>
---
drivers/block/loop.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 7f80653..ed85036 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1092,8 +1092,13 @@ loop_set_status(struct loop_device *lo, const struct
loop_info64 *info)
if (lo->lo_offset != info->lo_offset ||
lo->lo_sizelimit != info->lo_sizelimit) {
+ struct block_device *bdev = lo->lo_device;
+
if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
return -EFBIG;
+
+ bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
+ kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
}
loop_config_discard(lo);
--
1.7.9.5
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