Re: [PATCH] xfsprogs: io/copy_range: cover corner case (fd_in == fd_out)

[Zorro Lang <zlang@redhat.com>]

On Tue, Sep 03, 2019 at 07:59:43PM +0800, Zorro Lang wrote:
> On Tue, Sep 03, 2019 at 06:56:32PM +0800, Jianhong.Yin wrote:
> > Related bug:
> >   copy_file_range return "Invalid argument" when copy in the same file
> >   https://bugzilla.kernel.org/show_bug.cgi?id=202935
> > 
> > if argument of option -f is "-", use current file->fd as fd_in
> > 
> > Usage:
> >   xfs_io -c 'copy_range -f -' some_file
> > 
> > Signed-off-by: Jianhong Yin <yin-jianhong@163.com>
> > ---
> 
> Hi,
> 
> Actually, I'm thinking about if you need same 'fd' or same file path?
> If you just need same file path, I think
> 
>   # xfs_io -c "copy_range testfile" testfile
> 
> already can help that. The only one problem stop you doing that is
> "copy_dst_truncate()".
> 
> If all above I suppose is right, we can turn to talk about if that
> copy_dst_truncate() is necessary, or how can we skip it.

I just checked, the copy_dst_truncate() is only called when:

  if (src == 0 && dst == 0 && len == 0) {

So if you can give your reproducer a "length"(or offset), likes:

  # xfs_io -c "copy_range -l 64k testfile" testfile

You can avoid the copy_dst_truncate() too.

Is that helpful?

Thanks,
Zorro

> 
> Thanks,
> Zorro
> 
> >  io/copy_file_range.c | 27 ++++++++++++++++++---------
> >  1 file changed, 18 insertions(+), 9 deletions(-)
> > 
> > diff --git a/io/copy_file_range.c b/io/copy_file_range.c
> > index b7b9fd88..2dde8a31 100644
> > --- a/io/copy_file_range.c
> > +++ b/io/copy_file_range.c
> > @@ -28,6 +28,7 @@ copy_range_help(void)
> >                            at position 0\n\
> >   'copy_range -f 2' - copies all bytes from open file 2 into the current open file\n\
> >                            at position 0\n\
> > + 'copy_range -f -' - copies all bytes from current open file append the current open file\n\
> >  "));
> >  }
> >  
> > @@ -114,11 +115,15 @@ copy_range_f(int argc, char **argv)
> >  			}
> >  			break;
> >  		case 'f':
> > -			src_file_nr = atoi(argv[1]);
> > -			if (src_file_nr < 0 || src_file_nr >= filecount) {
> > -				printf(_("file value %d is out of range (0-%d)\n"),
> > -					src_file_nr, filecount - 1);
> > -				return 0;
> > +			if (strcmp(argv[1], "-"))
> > +				src_file_nr = (file - &filetable[0]) / sizeof(fileio_t);
> > +			else {
> > +				src_file_nr = atoi(argv[1]);
> > +				if (src_file_nr < 0 || src_file_nr >= filecount) {
> > +					printf(_("file value %d is out of range (0-%d)\n"),
> > +						src_file_nr, filecount - 1);
> > +					return 0;
> > +				}
> >  			}
> >  			/* Expect no src_path arg */
> >  			src_path_arg = 0;
> > @@ -147,10 +152,14 @@ copy_range_f(int argc, char **argv)
> >  		}
> >  		len = sz;
> >  
> > -		ret = copy_dst_truncate();
> > -		if (ret < 0) {
> > -			ret = 1;
> > -			goto out;
> > +		if (fd != file->fd) {
> > +			ret = copy_dst_truncate();
> > +			if (ret < 0) {
> > +				ret = 1;
> > +				goto out;
> > +			}
> > +		} else {
> > +			dst = sz;
> >  		}
> >  	}
> >  
> > -- 
> > 2.17.2
> >