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

[Andrew Vagin]

On Thu, Aug 04, 2016 at 07:49:35PM +0200, Stanislav Kinsburskiy wrote:
> 
> 
> 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.

Ok

Acked-by: Andrei Vagin <avagin at virtuozzo.com>
> 
> > > +		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;
> > > 
>