From: Ilya Dryomov Date: Mon, 12 Aug 2013 11:33:04 +0000 (+0300) Subject: Btrfs: rollback btrfs_device fields on umount X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=a1e8780a89ec13217fa1c8f86faf5546110e1402;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git Btrfs: rollback btrfs_device fields on umount It turns out we don't properly rollback in-core btrfs_device state on umount. We zero out ->bdev, ->in_fs_metadata and that's about it. In particular, we don't zero out ->generation, and this can lead to us refusing a mount -- a non-NULL fs_devices->latest_bdev is essential, but btrfs_close_extra_devices will happily assign NULL to ->latest_bdev if the first device on the dev_list happens to be missing and consequently has no bdev attached. This happens because since commit a6b0d5c8 btrfs_close_extra_devices adjusts ->latest_bdev, and in doing that, relies on the ->generation. Fix this, and possibly other problems, by zeroing out everything except for what device_list_add sets, so that a mount right after insmod and 'btrfs dev scan' is no different from any later mount in this respect. Signed-off-by: Ilya Dryomov Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index d38065eca7c9..ed685991b2c1 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -674,22 +674,19 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices) if (device->can_discard) fs_devices->num_can_discard--; - new_device = kmalloc(sizeof(*new_device), GFP_NOFS); - BUG_ON(!new_device); /* -ENOMEM */ - memcpy(new_device, device, sizeof(*new_device)); + new_device = btrfs_alloc_device(NULL, &device->devid, + device->uuid); + BUG_ON(IS_ERR(new_device)); /* -ENOMEM */ /* Safe because we are under uuid_mutex */ if (device->name) { name = rcu_string_strdup(device->name->str, GFP_NOFS); - BUG_ON(device->name && !name); /* -ENOMEM */ + BUG_ON(!name); /* -ENOMEM */ rcu_assign_pointer(new_device->name, name); } - new_device->bdev = NULL; - new_device->writeable = 0; - new_device->in_fs_metadata = 0; - new_device->can_discard = 0; - spin_lock_init(&new_device->io_lock); + list_replace_rcu(&device->dev_list, &new_device->dev_list); + new_device->fs_devices = device->fs_devices; call_rcu(&device->rcu, free_device); }