On 2018/03/27 21:39, Nikolay Borisov wrote:
>
>
> On 26.03.2018 11:30, Misono Tomohiro wrote:
>> This patch changes the behavior of rmdir(2) to allow it to delete
>> an empty subvolume by default, unless it is not a default subvolume
>> and send is not in progress.
>>
>> New function btrfs_delete_subvolume() is almost equal to the second half
>> of btrfs_ioctl_snap_destroy(). This function requires inode_lock for both
>> @dir and inode of @dentry. For rmdir(2) it is already acquired in vfs
>> layer before calling btrfs_rmdir().
>>
>> Note that while a non-privileged user cannot delete a read-only subvolume
>> by "btrfs subvolume delete" when user_subvol_rm_allowd mount option is
>> enabled, rmdir(2) can delete an empty read-only subvolume.
>> (However, rm -r cannot use for read-only subvolume containing files.)
>>
>> Signed-off-by: Tomohiro Misono <misono.tomohiro@xxxxxxxxxxxxxx>
>> ---
>> fs/btrfs/inode.c | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 142 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
>> index db66fa4fede6..b778776eee8e 100644
>> --- a/fs/btrfs/inode.c
>> +++ b/fs/btrfs/inode.c
>> @@ -4387,6 +4387,147 @@ noinline int may_destroy_subvol(struct btrfs_root *root)
>> return ret;
>> }
>>
>> +static int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry)
>> +{
>> + struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
>> + struct btrfs_root *root = BTRFS_I(dir)->root;
>> + struct inode *inode = d_inode(dentry);
>> + struct btrfs_root *dest = BTRFS_I(inode)->root;
>> + struct btrfs_trans_handle *trans;
>> + struct btrfs_block_rsv block_rsv;
>> + u64 root_flags;
>> + u64 qgroup_reserved;
>> + int ret;
>> + int err;
>> +
>> + /*
>> + * Don't allow to delete a subvolume with send in progress. This is
>> + * inside the i_mutex so the error handling that has to drop the bit
>> + * again is not run concurrently.
>> + */
>> + spin_lock(&dest->root_item_lock);
>> + root_flags = btrfs_root_flags(&dest->root_item);
>> + if (dest->send_in_progress == 0) {
>> + btrfs_set_root_flags(&dest->root_item,
>> + root_flags | BTRFS_ROOT_SUBVOL_DEAD);
>> + spin_unlock(&dest->root_item_lock);
>> + } else {
>> + spin_unlock(&dest->root_item_lock);
>> + btrfs_warn(fs_info,
>> + "Attempt to delete subvolume %llu during send",
>> + dest->root_key.objectid);
>> + err = -EPERM;
>> + return err;
>> + }
>> +
>> + down_write(&fs_info->subvol_sem);
>> +
>> + err = may_destroy_subvol(dest);
>> + if (err)
>> + goto out_up_write;
>> +
>> + btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
>> + /*
>> + * One for dir inode, two for dir entries, two for root
>> + * ref/backref.
>> + */
>> + err = btrfs_subvolume_reserve_metadata(root, &block_rsv,
>> + 5, &qgroup_reserved, true);
>> + if (err)
>> + goto out_up_write;
>> +
>> + trans = btrfs_start_transaction(root, 0);
>> + if (IS_ERR(trans)) {
>> + err = PTR_ERR(trans);
>> + goto out_release;
>> + }
>> + trans->block_rsv = &block_rsv;
>> + trans->bytes_reserved = block_rsv.size;
>> +
>> + btrfs_record_snapshot_destroy(trans, BTRFS_I(dir));
>> +
>> + ret = btrfs_unlink_subvol(trans, root, dir,
>> + dest->root_key.objectid,
>> + dentry->d_name.name,
>> + dentry->d_name.len);
>> + if (ret) {
>> + err = ret;
>> + btrfs_abort_transaction(trans, ret);
>> + goto out_end_trans;
>> + }
>> +
>> + btrfs_record_root_in_trans(trans, dest);
>> +
>> + memset(&dest->root_item.drop_progress, 0,
>> + sizeof(dest->root_item.drop_progress));
>> + dest->root_item.drop_level = 0;
>> + btrfs_set_root_refs(&dest->root_item, 0);
>> +
>> + if (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) {
>> + ret = btrfs_insert_orphan_item(trans,
>> + fs_info->tree_root,
>> + dest->root_key.objectid);
>> + if (ret) {
>> + btrfs_abort_transaction(trans, ret);
>> + err = ret;
>> + goto out_end_trans;
>> + }
>> + }
>> +
>> + ret = btrfs_uuid_tree_rem(trans, fs_info, dest->root_item.uuid,
>> + BTRFS_UUID_KEY_SUBVOL,
>> + dest->root_key.objectid);
>> + if (ret && ret != -ENOENT) {
>> + btrfs_abort_transaction(trans, ret);
>> + err = ret;
>> + goto out_end_trans;
>> + }
>> + if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
>> + ret = btrfs_uuid_tree_rem(trans, fs_info,
>> + dest->root_item.received_uuid,
>> + BTRFS_UUID_KEY_RECEIVED_SUBVOL,
>> + dest->root_key.objectid);
>> + if (ret && ret != -ENOENT) {
>> + btrfs_abort_transaction(trans, ret);
>> + err = ret;
>> + goto out_end_trans;
>> + }
>> + }
>> +
>> +out_end_trans:
>> + trans->block_rsv = NULL;
>> + trans->bytes_reserved = 0;
>> + ret = btrfs_end_transaction(trans);
>> + if (ret && !err)
>> + err = ret;
>> + inode->i_flags |= S_DEAD;
>> +out_release:
>> + btrfs_subvolume_release_metadata(fs_info, &block_rsv);
>> +out_up_write:
>> + up_write(&fs_info->subvol_sem);
>> + if (err) {
>> + spin_lock(&dest->root_item_lock);
>> + root_flags = btrfs_root_flags(&dest->root_item);
>> + btrfs_set_root_flags(&dest->root_item,
>> + root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
>> + spin_unlock(&dest->root_item_lock);
>> + }
>> +
>> + if (!err) {
>
> nit: Why 2 if branches and not a single if {} else {} construct?
Thanks, I will update in v2.
>
>> + d_invalidate(dentry);
>> + btrfs_invalidate_inodes(dest);
>> + ASSERT(dest->send_in_progress == 0);
>> +
>> + /* the last ref */
>> + if (dest->ino_cache_inode) {
>> + iput(dest->ino_cache_inode);
>> + dest->ino_cache_inode = NULL;
>> + }
>> + }
>> +
>> + return err;
>> +}
>> +
>> static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
>> {
>> struct inode *inode = d_inode(dentry);
>> @@ -4398,7 +4539,7 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
>> if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
>> return -ENOTEMPTY;
>> if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID)
>> - return -EPERM;
>> + return btrfs_delete_subvolume(dir, dentry);
>>
>> trans = __unlink_start_trans(dir);
>> if (IS_ERR(trans))
>>
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