[PATCH] block: loop: remove & invalidate partitions when detaching

[Ming Lei <ming.lei@redhat.com>]

When detaching loop disk, neither we remove loop partitions, nor
invalidate them. This way may cause data loss, and often confuse
people.

This patch fixes the above issue by removing & invalidating loop
partitions in loop_clr_fd(),

Reported-by: reddot.rocks@gmail.com
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/genhd.c         | 15 +++++++++++----
 drivers/block/loop.c  |  4 ++--
 include/linux/genhd.h |  1 +
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 96a66f671720..24c66e940c0c 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -695,14 +695,11 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
 }
 EXPORT_SYMBOL(device_add_disk);
 
-void del_gendisk(struct gendisk *disk)
+void del_gendisk_partitions(struct gendisk *disk)
 {
 	struct disk_part_iter piter;
 	struct hd_struct *part;
 
-	blk_integrity_del(disk);
-	disk_del_events(disk);
-
 	/* invalidate stuff */
 	disk_part_iter_init(&piter, disk,
 			     DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
@@ -714,7 +711,17 @@ void del_gendisk(struct gendisk *disk)
 	disk_part_iter_exit(&piter);
 
 	invalidate_partition(disk, 0);
+}
+EXPORT_SYMBOL(del_gendisk_partitions);
+
+void del_gendisk(struct gendisk *disk)
+{
+	blk_integrity_del(disk);
+	disk_del_events(disk);
+
+	del_gendisk_partitions(disk);
 	bdev_unhash_inode(disk_devt(disk));
+
 	set_capacity(disk, 0);
 	disk->flags &= ~GENHD_FL_UP;
 
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index bc8e61506968..a84c7befcc94 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1021,6 +1021,8 @@ static int loop_clr_fd(struct loop_device *lo)
 	if (filp == NULL)
 		return -EINVAL;
 
+	del_gendisk_partitions(lo->lo_disk);
+
 	/* freeze request queue during the transition */
 	blk_mq_freeze_queue(lo->lo_queue);
 
@@ -1060,8 +1062,6 @@ static int loop_clr_fd(struct loop_device *lo)
 	module_put(THIS_MODULE);
 	blk_mq_unfreeze_queue(lo->lo_queue);
 
-	if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
-		loop_reread_partitions(lo, bdev);
 	lo->lo_flags = 0;
 	if (!part_shift)
 		lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 5144ebe046c9..ae41535e705c 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -397,6 +397,7 @@ static inline void add_disk(struct gendisk *disk)
 }
 
 extern void del_gendisk(struct gendisk *gp);
+extern void del_gendisk_partitions(struct gendisk *gp);
 extern struct gendisk *get_gendisk(dev_t dev, int *partno);
 extern struct block_device *bdget_disk(struct gendisk *disk, int partno);
 
-- 
2.9.5