So far we initialized bd_bdi only in bdget(). That is fine for normal
bdev inodes however for the special case of the root inode of
blockdev_superblock that function is never called and thus bd_bdi is
left uninitialized. As a result bdev_evict_inode() may oops doing
bdi_put(root->bd_bdi) on that inode as can be seen when doing:
mount -t bdev none /mnt
Fix the problem by initializing bd_bdi when first allocating the inode
and then reinitializing bd_bdi in bdev_evict_inode().
Thanks to syzkaller team for finding the problem.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Fixes:
b1d2dc5659b4 ("block: Make blk_get_backing_dev_info() safe without open bdev")
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Change-Id: I9c34ca321ab311936946187ed21e25d67caf5ba5
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
Git-commit:
7ee143f46cb1f58ee07194076b9a3e6ea3f27ad3
[riteshh@codeaurora.org: resolved merge conflicts]
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
#ifdef CONFIG_SYSFS
INIT_LIST_HEAD(&bdev->bd_holder_disks);
#endif
+ bdev->bd_bdi = &noop_backing_dev_info;
inode_init_once(&ei->vfs_inode);
/* Initialize mutex for freeze. */
mutex_init(&bdev->bd_fsfreeze_mutex);
}
list_del_init(&bdev->bd_list);
spin_unlock(&bdev_lock);
- if (bdev->bd_bdi != &noop_backing_dev_info)
+ if (bdev->bd_bdi != &noop_backing_dev_info) {
bdi_put(bdev->bd_bdi);
+ bdev->bd_bdi = &noop_backing_dev_info;
+ }
}
static const struct super_operations bdev_sops = {
bdev->bd_contains = NULL;
bdev->bd_super = NULL;
bdev->bd_inode = inode;
- bdev->bd_bdi = &noop_backing_dev_info;
bdev->bd_block_size = (1 << inode->i_blkbits);
bdev->bd_part_count = 0;
bdev->bd_invalidated = 0;