On 10/05/2017 10:22 AM, Nikolay Borisov wrote:
> Currently when a read-only snapshot is received and subsequently its ro
> property
> is set to false i.e. switched to rw-mode the received_uuid of that subvol
> remains
> intact. However, once the received volume is switched to RW mode we cannot
> guaranteee that it contains the same data, so it makes sense to remove the
> received uuid. The presence of the received_uuid can also cause problems when
> the volume is being send.
>
> Signed-off-by: Nikolay Borisov <nbori...@suse.com>
> Suggested-by: David Sterba <dste...@suse.cz>
> ---
>
> v4:
> * Put the uuid tree removal code after the lightweight 'send in progress'
> check and don't move btrfs_start_transaction as suggested by David
>
> v3:
> * Rework the patch considering latest feedback from David Sterba i.e.
> explicitly use btrfs_end_transaction
>
> fs/btrfs/ioctl.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index ee4ee7cbba72..9328c091854b 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -1775,6 +1775,7 @@ static noinline int btrfs_ioctl_subvol_setflags(struct
> file *file,
> struct btrfs_trans_handle *trans;
> u64 root_flags;
> u64 flags;
> + bool clear_received_uuid = false;
> int ret = 0;
>
> if (!inode_owner_or_capable(inode))
> @@ -1824,6 +1825,7 @@ static noinline int btrfs_ioctl_subvol_setflags(struct
> file *file,
> btrfs_set_root_flags(&root->root_item,
> root_flags & ~BTRFS_ROOT_SUBVOL_RDONLY);
> spin_unlock(&root->root_item_lock);
> + clear_received_uuid = true;
> } else {
> spin_unlock(&root->root_item_lock);
> btrfs_warn(fs_info,
> @@ -1840,6 +1842,24 @@ static noinline int btrfs_ioctl_subvol_setflags(struct
> file *file,
> goto out_reset;
> }
>
> + if (clear_received_uuid) {
> + if (!btrfs_is_empty_uuid(root->root_item.received_uuid)) {
> + ret = btrfs_uuid_tree_rem(trans, fs_info,
> + root->root_item.received_uuid,
> + BTRFS_UUID_KEY_RECEIVED_SUBVOL,
> + root->root_key.objectid);
> +
> + if (ret && ret != -ENOENT) {
> + btrfs_abort_transaction(trans, ret);
> + btrfs_end_transaction(trans);
> + goto out_reset;
> + }
> +
> + memset(root->root_item.received_uuid, 0,
> + BTRFS_UUID_SIZE);
Shouldn't we also wipe the other related fields here, like stime, rtime,
stransid, rtransid?
> + }
> + }
> +
> ret = btrfs_update_root(trans, fs_info->tree_root,
> &root->root_key, &root->root_item);
> if (ret < 0) {
>
--
Hans van Kranenburg
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