Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 01ea5063 authored by Signed-off-by: Jan Kara's avatar Signed-off-by: Jan Kara Committed by Jens Axboe
Browse files

block: Fix race during disk initialization 

When a new disk is being discovered, add_disk() first ties the bdev to gendisk
(via register_disk()->blkdev_get()) and only after that calls
bdi_register_bdev(). Because register_disk() also creates disk's kobject, it
can happen that userspace manages to open and modify the device's data (or
inode) before its BDI is properly initialized leading to a warning in
__mark_inode_dirty().

Fix the problem by registering BDI early enough.

This patch addresses https://bugzilla.kernel.org/show_bug.cgi?id=16312



Cc: stable@kernel.org
Reported-by: default avatarLarry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 2786c4e5

block/genhd.c

+4 −2
Original line number Diff line number Diff line
@@ -541,13 +541,15 @@ void add_disk(struct gendisk *disk) 
	disk->major = MAJOR(devt);

	disk->first_minor = MINOR(devt);



	/* Register BDI before referencing it from bdev */ 

	bdi = &disk->queue->backing_dev_info;

	bdi_register_dev(bdi, disk_devt(disk));



	blk_register_region(disk_devt(disk), disk->minors, NULL,

			    exact_match, exact_lock, disk);

	register_disk(disk);

	blk_register_queue(disk);



	bdi = &disk->queue->backing_dev_info;

	bdi_register_dev(bdi, disk_devt(disk));

	retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,

				   "bdi");

	WARN_ON(retval);