From 165a5e22fafb127ecb5914e12e8c32a1f0d3f820 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 8 Feb 2017 08:05:56 +0100 Subject: [PATCH] block: Move bdi_unregister() to del_gendisk() Commit 6cd18e711dd8 "block: destroy bdi before blockdev is unregistered." moved bdi unregistration (at that time through bdi_destroy()) from blk_release_queue() to blk_cleanup_queue() because it needs to happen before blk_unregister_region() call in del_gendisk() for MD. SCSI though will free up the device number from sd_remove() called through a maze of callbacks from device_del() in __scsi_remove_device() before blk_cleanup_queue() and thus similar races as described in 6cd18e711dd8 can happen for SCSI as well as reported by Omar [1]. Moving bdi_unregister() to del_gendisk() works for MD and fixes the problem for SCSI since del_gendisk() gets called from sd_remove() before freeing the device number. This also makes device_add_disk() (calling bdi_register_owner()) more symmetric with del_gendisk(). [1] http://marc.info/?l=linux-block&m=148554717109098&w=2 Tested-by: Lekshmi Pillai Acked-by: Tejun Heo Signed-off-by: Jan Kara Tested-by: Omar Sandoval Signed-off-by: Jens Axboe --- block/blk-core.c | 1 - block/genhd.c | 5 +++++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/block/blk-core.c b/block/blk-core.c index b9e857f4afe8..1086dac8724c 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -578,7 +578,6 @@ void blk_cleanup_queue(struct request_queue *q) q->queue_lock = &q->__queue_lock; spin_unlock_irq(lock); - bdi_unregister(q->backing_dev_info); put_disk_devt(q->disk_devt); /* @q is and will stay empty, shutdown and put */ diff --git a/block/genhd.c b/block/genhd.c index 2f444b87a5f2..b26a5ea115d0 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -681,6 +681,11 @@ void del_gendisk(struct gendisk *disk) disk->flags &= ~GENHD_FL_UP; sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi"); + /* + * Unregister bdi before releasing device numbers (as they can get + * reused and we'd get clashes in sysfs). + */ + bdi_unregister(disk->queue->backing_dev_info); blk_unregister_queue(disk); blk_unregister_region(disk_devt(disk), disk->minors);