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| author | Jan Kara <jack@suse.cz> | 2017-03-02 16:50:13 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-03-02 08:56:59 -0700 |
| commit | a5a79d00017c9eee68a9bcb40d5dfd6f45f17461 (patch) | |
| tree | dc1803bee107865dbea5c4434bad158a15a66ced /fs/block_dev.c | |
| parent | e02898b423802b1f3a3aaa7f16e896da069ba8f7 (diff) | |
| download | lwn-a5a79d00017c9eee68a9bcb40d5dfd6f45f17461.tar.gz lwn-a5a79d00017c9eee68a9bcb40d5dfd6f45f17461.zip | |
block: Initialize bd_bdi on inode initialization
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>
Diffstat (limited to 'fs/block_dev.c')
| -rw-r--r-- | fs/block_dev.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index 77c30f15a02c..2eca00ec4370 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -870,6 +870,7 @@ static void init_once(void *foo) #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); @@ -884,8 +885,10 @@ static void bdev_evict_inode(struct inode *inode) spin_lock(&bdev_lock); 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 = { @@ -988,7 +991,6 @@ struct block_device *bdget(dev_t dev) bdev->bd_contains = NULL; bdev->bd_super = NULL; bdev->bd_inode = inode; - bdev->bd_bdi = &noop_backing_dev_info; bdev->bd_block_size = i_blocksize(inode); bdev->bd_part_count = 0; bdev->bd_invalidated = 0; |