[CRIU] [PATCH] files-reg: discover file system type only if file is going to be dumped

[Stanislav Kinsburskiy]

04.08.2016 19:28, Andrew Vagin пишет:
> On Tue, Aug 02, 2016 at 07:05:18PM +0300, Stanislav Kinsburskiy wrote:
>> Instead of calling it in fill_fd_params_special (which is called for any found
>> path).
>> This reduces amount of system calls on dump.
>>
>> Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
>> ---
>>   criu/cr-dump.c |   47 +++++++++++++++++++++++++++--------------------
>>   1 file changed, 27 insertions(+), 20 deletions(-)
>>
>> diff --git a/criu/cr-dump.c b/criu/cr-dump.c
>> index 2288908..e51e258 100644
>> --- a/criu/cr-dump.c
>> +++ b/criu/cr-dump.c
>> @@ -215,8 +215,6 @@ static int collect_fds(pid_t pid, struct parasite_drain_fd **dfds)
>>   
>>   static int fill_fd_params_special(int fd, struct fd_parms *p)
>>   {
>> -	struct statfs fst;
>> -
>>   	*p = FD_PARMS_INIT;
>>   
>>   	if (fstat(fd, &p->stat) < 0) {
>> @@ -227,13 +225,28 @@ static int fill_fd_params_special(int fd, struct fd_parms *p)
>>   	if (get_fd_mntid(fd, &p->mnt_id))
>>   		return -1;
>>   
>> -	if (fstatfs(fd, &fst)) {
>> -		pr_perror("Unable to statfs fd %d", fd);
>> +	return 0;
>> +}
>> +
>> +static int get_fs_type(int lfd)
>> +{
>> +	struct statfs fst;
>> +
>> +	if (fstatfs(lfd, &fst)) {
>> +		pr_perror("Unable to statfs fd %d", lfd);
>>   		return -1;
>>   	}
>> +	return fst.f_type;
>> +}
>>   
>> -	p->fs_type = fst.f_type;
>> -
>> +static int dump_one_reg_file_cond(int lfd, u32 *id, struct fd_parms *parms)
>> +{
>> +	if (fd_id_generate_special(parms, id)) {
>> +		parms->fs_type = get_fs_type(lfd);
>> +		if (parms->fs_type < 0)
>> +			return -1;
> Why do we get fs_type here. Can we move it in dump_one_reg_file?

Because dump_one_reg_file accepts const pointer.
And it looks reasonable to keep it const, since dump_one_reg_file has to 
dump, but not to investigate.

>> +		return dump_one_reg_file(lfd, *id, parms);
>> +	}
>>   	return 0;
>>   }
>>   
>> @@ -249,8 +262,7 @@ static int dump_task_exe_link(pid_t pid, MmEntry *mm)
>>   	if (fill_fd_params_special(fd, &params))
>>   		return -1;
>>   
>> -	if (fd_id_generate_special(&params, &mm->exe_file_id))
>> -		ret = dump_one_reg_file(fd, mm->exe_file_id, &params);
>> +	ret = dump_one_reg_file_cond(fd, &mm->exe_file_id, &params);
>>   
>>   	close(fd);
>>   	return ret;
>> @@ -272,11 +284,9 @@ static int dump_task_fs(pid_t pid, struct parasite_dump_misc *misc, struct cr_im
>>   	if (fill_fd_params_special(fd, &p))
>>   		return -1;
>>   
>> -	if (fd_id_generate_special(&p, &fe.cwd_id)) {
>> -		ret = dump_one_reg_file(fd, fe.cwd_id, &p);
>> -		if (ret < 0)
>> -			return ret;
>> -	}
>> +	ret = dump_one_reg_file_cond(fd, &fe.cwd_id, &p);
>> +	if (ret < 0)
>> +		return ret;
>>   
>>   	close(fd);
>>   
>> @@ -287,11 +297,9 @@ static int dump_task_fs(pid_t pid, struct parasite_dump_misc *misc, struct cr_im
>>   	if (fill_fd_params_special(fd, &p))
>>   		return -1;
>>   
>> -	if (fd_id_generate_special(&p, &fe.root_id)) {
>> -		ret = dump_one_reg_file(fd, fe.root_id, &p);
>> -		if (ret < 0)
>> -			return ret;
>> -	}
>> +	ret = dump_one_reg_file_cond(fd, &fe.root_id, &p);
>> +	if (ret < 0)
>> +		return ret;
>>   
>>   	close(fd);
>>   
>> @@ -398,8 +406,7 @@ static int dump_filemap(struct vma_area *vma_area, int fd)
>>   
>>   	/* Flags will be set during restore in open_filmap() */
>>   
>> -	if (fd_id_generate_special(&p, &id))
>> -		ret = dump_one_reg_file(fd, id, &p);
>> +	ret = dump_one_reg_file_cond(fd, &id, &p);
>>   
>>   	vma->shmid = id;
>>   	return ret;
>>