block: delete partitions later in del_gendisk

Delay dropping the block_devices for partitions in del_gendisk until
after the call to blk_mark_disk_dead, so that we can implementat
notification of removed devices in blk_mark_disk_dead.

This requires splitting a lower-level drop_partition helper out of
delete_partition and using that from del_gendisk, while having a
common loop for the whole device and partitions that calls
remove_inode_hash, fsync_bdev and __invalidate_device before the
call to blk_mark_disk_dead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 19 insertions, 5 deletions

diff --git a/block/genhd.c b/block/genhd.c
index 6fa926a02d85..a668d2f02087 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -615,6 +615,8 @@ EXPORT_SYMBOL_GPL(blk_mark_disk_dead);
 void del_gendisk(struct gendisk *disk)
 {
 	struct request_queue *q = disk->queue;
+	struct block_device *part;
+	unsigned long idx;
 
 	might_sleep();
 
@@ -623,16 +625,28 @@ void del_gendisk(struct gendisk *disk)
 
 	disk_del_events(disk);
 
+	/*
+	 * Prevent new openers by unlinked the bdev inode, and write out
+	 * dirty data before marking the disk dead and stopping all I/O.
+	 */
 	mutex_lock(&disk->open_mutex);
-	remove_inode_hash(disk->part0->bd_inode);
-	blk_drop_partitions(disk);
+	xa_for_each(&disk->part_tbl, idx, part) {
+		remove_inode_hash(part->bd_inode);
+		fsync_bdev(part);
+		__invalidate_device(part, true);
+	}
 	mutex_unlock(&disk->open_mutex);
 
-	fsync_bdev(disk->part0);
-	__invalidate_device(disk->part0, true);
-
 	blk_mark_disk_dead(disk);
 
+	/*
+	 * Drop all partitions now that the disk is marked dead.
+	 */
+	mutex_lock(&disk->open_mutex);
+	xa_for_each_start(&disk->part_tbl, idx, part, 1)
+		drop_partition(part);
+	mutex_unlock(&disk->open_mutex);
+
 	if (!(disk->flags & GENHD_FL_HIDDEN)) {
 		sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");