linux/block
Jan Kara 56c0908c85 genhd: Fix BUG in blkdev_open()
When two blkdev_open() calls for a partition race with device removal
and recreation, we can hit BUG_ON(!bd_may_claim(bdev, whole, holder)) in
blkdev_open(). The race can happen as follows:

CPU0				CPU1			CPU2
							del_gendisk()
							  bdev_unhash_inode(part1);

blkdev_open(part1, O_EXCL)	blkdev_open(part1, O_EXCL)
  bdev = bd_acquire()		  bdev = bd_acquire()
  blkdev_get(bdev)
    bd_start_claiming(bdev)
      - finds old inode 'whole'
      bd_prepare_to_claim() -> 0
							  bdev_unhash_inode(whole);
							<device removed>
							<new device under same
							 number created>
				  blkdev_get(bdev);
				    bd_start_claiming(bdev)
				      - finds new inode 'whole'
				      bd_prepare_to_claim()
					- this also succeeds as we have
					  different 'whole' here...
					- bad things happen now as we
					  have two exclusive openers of
					  the same bdev

The problem here is that block device opens can see various intermediate
states while gendisk is shutting down and then being recreated.

We fix the problem by introducing new lookup_sem in gendisk that
synchronizes gendisk deletion with get_gendisk() and furthermore by
making sure that get_gendisk() does not return gendisk that is being (or
has been) deleted. This makes sure that once we ever manage to look up
newly created bdev inode, we are also guaranteed that following
get_gendisk() will either return failure (and we fail open) or it
returns gendisk for the new device and following bdget_disk() will
return new bdev inode (i.e., blkdev_open() follows the path as if it is
completely run after new device is created).

Reported-and-analyzed-by: Hou Tao <houtao1@huawei.com>
Tested-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-02-26 09:48:42 -07:00
..
partitions partitions/msdos: Unable to mount UFS 44bsd partitions 2018-01-10 09:12:16 -07:00
badblocks.c badblocks: fix wrong return value in badblocks_set if badblocks are disabled 2017-11-03 11:29:50 -07:00
bfq-cgroup.c block, bfq: put async queues for root bfq groups too 2018-01-09 08:45:25 -07:00
bfq-iosched.c block, bfq: add requeue-request hook 2018-02-07 15:17:46 -07:00
bfq-iosched.h block, bfq: limit sectors served with interactive weight raising 2018-01-18 08:21:37 -07:00
bfq-wf2q.c block, bfq: limit sectors served with interactive weight raising 2018-01-18 08:21:37 -07:00
bio-integrity.c block: Fix __bio_integrity_endio() documentation 2018-01-17 09:59:33 -07:00
bio.c Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
blk-cgroup.c genhd: Add helper put_disk_and_module() 2018-02-26 09:48:42 -07:00
blk-core.c block: Add should_fail_bio() for bpf error injection 2018-02-06 15:09:51 -07:00
blk-exec.c blk-mq-sched: remove unused 'can_block' arg from blk_mq_sched_insert_request 2018-01-17 09:49:21 -07:00
blk-flush.c blk-mq: don't allocate driver tag upfront for flush rq 2017-11-04 12:40:13 -06:00
blk-integrity.c block: switch bios to blk_status_t 2017-06-09 09:27:32 -06:00
blk-ioc.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-lib.c block: add bdev_read_only() checks to common helpers 2018-01-18 12:57:19 -07:00
blk-map.c Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
blk-merge.c blk-mq: fix discard merge with scheduler attached 2018-02-01 14:01:02 -07:00
blk-mq-cpumap.c blk-mq: map queues to all present CPUs 2017-07-24 10:01:31 -06:00
blk-mq-debugfs.c blk-mq-debugfs: don't allow write on attributes with seq_operations set 2018-01-24 09:46:09 -07:00
blk-mq-debugfs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-mq-pci.c blk-mq-pci: add a fallback when pci_irq_get_affinity returns NULL 2017-08-18 08:08:14 -06:00
blk-mq-rdma.c block: Add rdma affinity based queue mapping helper 2017-08-08 14:58:03 -04:00
blk-mq-sched.c blk-mq-sched: Enable merging discard bio into request 2018-02-01 14:45:11 -07:00
blk-mq-sched.h blk-mq-sched: remove unused 'can_block' arg from blk_mq_sched_insert_request 2018-01-17 09:49:21 -07:00
blk-mq-sysfs.c block: properly protect the 'queue' kobj in blk_unregister_queue 2018-01-15 08:41:38 -07:00
blk-mq-tag.c blk-mq: improve heavily contended tag case 2017-12-22 11:09:37 -07:00
blk-mq-tag.h Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
blk-mq-virtio.c
blk-mq.c blk-mq: don't call io sched's .requeue_request when requeueing rq to ->dispatch 2018-02-24 15:55:54 -07:00
blk-mq.h blk-mq: Rename blk_mq_request_direct_issue() into blk_mq_request_issue_directly() 2018-01-19 12:51:59 -07:00
blk-settings.c block: remove __bio_kmap_atomic 2017-11-10 19:53:25 -07:00
blk-softirq.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-stat.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
blk-stat.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-sysfs.c block: Protect less code with sysfs_lock in blk_{un,}register_queue() 2018-01-18 12:54:44 -07:00
blk-tag.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-throttle.c Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
blk-timeout.c block: add accessors for setting/querying request deadline 2018-01-10 11:47:47 -07:00
blk-wbt.c blk-wbt: account flush requests correctly 2018-02-06 14:14:03 -07:00
blk-wbt.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blk-zoned.c block: introduce zoned block devices zone write locking 2018-01-05 09:22:17 -07:00
blk.h Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
bounce.c Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
bsg-lib.c block: Fix kernel-doc warnings reported when building with W=1 2018-01-09 11:15:17 -07:00
bsg.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
cfq-iosched.c block/cfq: cache rightmost rb_node 2017-09-08 18:26:49 -07:00
cmdline-parser.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compat_ioctl.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
deadline-iosched.c deadline-iosched: Introduce zone locking support 2018-01-05 09:22:17 -07:00
elevator.c block: Document scheduler modification locking requirements 2018-01-18 12:54:42 -07:00
genhd.c genhd: Fix BUG in blkdev_open() 2018-02-26 09:48:42 -07:00
ioctl.c block: pass inclusive 'lend' parameter to truncate_inode_pages_range 2018-02-23 15:20:19 -07:00
ioprio.c block: Add fallthrough markers to switch statements 2017-06-21 11:46:07 -06:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig.iosched License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kyber-iosched.c block: kyber: fix domain token leak during requeue 2018-02-24 15:55:54 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mq-deadline.c mq-deadline: make it clear that __dd_dispatch_request() works on all hw queues 2018-01-06 09:23:11 -07:00
noop-iosched.c
opal_proto.h block: sed-opal: Set MBRDone on S3 resume path if TPER is MBREnabled 2017-09-11 09:45:52 -06:00
partition-generic.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
scsi_ioctl.c block: silently forbid sending any ioctl to a partition 2018-01-10 12:30:37 -07:00
sed-opal.c block: sed-opal: Set MBRDone on S3 resume path if TPER is MBREnabled 2017-09-11 09:45:52 -06:00
t10-pi.c t10-pi: Move opencoded contants to common header 2017-07-03 16:56:25 -06:00