[CRIU] [PATCH v4 5/6] files-reg: Recreate deleted parent directories during restore of ghost file

[Pavel Emelyanov]

>>> +	int err, count = 0;
>>> +	struct stat st;
>>> +
>>> +	sprintf_parent_dir(pdir, path);
>>> +
>>> +	if (fstatat(mntns_root, pdir, &st, AT_EMPTY_PATH) == 0)
>>
>> Is this fstatat() required? The below mkdir() would return EEXISTS anyway.
> 
> fstatat() checks parent path, and it's a likely case when the whole hierarhy exists.
> 
> mkdir() creates directories from grand..grand parent to parent:
> 
> /dir
> /dir/subdir
> /dir/subdir/childsubdir
> ...
> 
> I don't think it's good to use mkdir for the whole hierarhy for every file.

Ah! OK, this makes sense. Plz, write this as code comment to the fstatat() call.

> Maybe you mean something else?
> 
>>> +		return 0;
>>> +	if (errno != ENOENT) {
>>> +		pr_perror("Can't stat %s", pdir);
>>> +		return -1;
>>> +	}
>>> +
>>> +	p = pdir;
>>> +	do {
>>> +		p = strchr(p, '/');
>>> +		if (p)
>>> +			*p = '\0';
>>> +
>>> +		err = mkdirat(mntns_root, pdir, 0777);
>>> +		if (err && errno != EEXIST) {
>>> +			pr_perror("Can't create dir: %s AT %d", pdir, mntns_root);
>>> +			goto cleanup;
>>> +		} else if (!err) {
>>> +			pr_debug("Created parent dir: %s AT %d\n", pdir, mntns_root);
>>> +			count++;
>>> +		}
>>> +
>>> +		if (p)
>>> +			*p++ = '/';
>>> +	} while (p);
>>> +
>>> +	return count;
>>> +cleanup:
>>> +	rm_parent_dirs(mntns_root, pdir, count);
>>> +	return -1;
>>> +}
>>> +
>>>  /*
>>>   * This routine properly resolves d's path handling ghost/link-remaps.
>>>   * The open_cb is a routine that does actual open, it differs for
>>>   * files, directories, fifos, etc.
>>>   */
>>>  
>>> -static int rfi_remap(struct reg_file_info *rfi)
>>> +static int rfi_remap(struct reg_file_info *rfi, int *level)
>>>  {
>>>  	struct mount_info *mi, *rmi, *tmi;
>>>  	char _path[PATH_MAX], *path = _path;
>>> @@ -1269,14 +1346,23 @@ static int rfi_remap(struct reg_file_info *rfi)
>>>  	mntns_root = mntns_get_root_fd(tmi->nsid);
>>>  
>>>  out_root:
>>> -	return linkat_hard(mntns_root, rpath, mntns_root, path, rfi->remap->owner);
>>> +	*level = make_parent_dirs_if_need(mntns_root, path);
>>> +	if (*level < 0)
>>> +		return -1;
>>> +
>>> +	if (linkat_hard(mntns_root, rpath, mntns_root, path, rfi->remap->owner) < 0) {
>>> +		rm_parent_dirs(mntns_root, path, *level);
>>> +		return -1;
>>> +	}
>>> +
>>> +	return 0;
>>>  }
>>>  
>>>  int open_path(struct file_desc *d,
>>>  		int(*open_cb)(int mntns_root, struct reg_file_info *, void *), void *arg)
>>>  {
>>> +	int tmp, mntns_root, level;
>>>  	struct reg_file_info *rfi;
>>> -	int tmp, mntns_root;
>>>  	char *orig_path = NULL;
>>>  
>>>  	if (inherited_fd(d, &tmp))
>>> @@ -1292,7 +1378,7 @@ int open_path(struct file_desc *d,
>>>  			 */
>>>  			orig_path = rfi->path;
>>>  			rfi->path = rfi->remap->rpath;
>>> -		} else if (rfi_remap(rfi) < 0) {
>>> +		} else if (rfi_remap(rfi, &level) < 0) {
>>>  			static char tmp_path[PATH_MAX];
>>>  
>>>  			if (errno != EEXIST) {
>>> @@ -1316,7 +1402,7 @@ int open_path(struct file_desc *d,
>>>  			snprintf(tmp_path, sizeof(tmp_path), "%s.cr_link", orig_path);
>>>  			pr_debug("Fake %s -> %s link\n", rfi->path, rfi->remap->rpath);
>>>  
>>> -			if (rfi_remap(rfi) < 0) {
>>> +			if (rfi_remap(rfi, &level) < 0) {
>>>  				pr_perror("Can't create even fake link!");
>>>  				return -1;
>>>  			}
>>> @@ -1356,6 +1442,7 @@ int open_path(struct file_desc *d,
>>>  	if (rfi->remap) {
>>>  		if (!rfi->remap->is_dir) {
>>>  			unlinkat(mntns_root, rfi->path, 0);
>>> +			rm_parent_dirs(mntns_root, rfi->path, level);
>>>  		}
>>>  
>>>  		BUG_ON(!rfi->remap->users);
>>>
>>> .
>>>
>>
> .
>