I've send new patch do same work
----- 原始邮件 -----
> 发件人: "Zorro Lang" <zlang@xxxxxxxxxx>
> 收件人: "Jianhong.Yin" <yin-jianhong@xxxxxxx>
> 抄送: linux-xfs@xxxxxxxxxxxxxxx, jiyin@xxxxxxxxxx
> 发送时间: 星期四, 2019年 9 月 05日 下午 1:02:35
> 主题: Re: [PATCH] xfsprogs: copy_range don't truncate dstfile if same with srcfile
>
> On Wed, Sep 04, 2019 at 02:32:22PM +0800, Jianhong.Yin wrote:
> > now if we do copy_range in same file without any extra option
> > will truncate the file, and not any document indicate this default
> > action. that's risky to users.
> >
> > '''
> > $ LANG=C ll testfile
> > -rw-rw-r--. 1 yjh yjh 4054 Sep 4 14:22 testfile
> > $ ./xfs_io -c 'copy_range testfile' testfile
> > $ LANG=C ll testfile
> > -rw-rw-r--. 1 yjh yjh 4054 Sep 4 14:23 testfile
> > '''
> >
> > Signed-off-by: Jianhong Yin <yin-jianhong@xxxxxxx>
> > ---
> > io/copy_file_range.c | 23 +++++++++++++++++++----
> > 1 file changed, 19 insertions(+), 4 deletions(-)
> >
> > diff --git a/io/copy_file_range.c b/io/copy_file_range.c
> > index b7b9fd88..487041c0 100644
> > --- a/io/copy_file_range.c
> > +++ b/io/copy_file_range.c
> > @@ -75,6 +75,19 @@ copy_dst_truncate(void)
> > return ret;
> > }
> >
> > +int is_same_file(int fd1, int fd2) {
> > + struct stat stat1, stat2;
> > + if (fstat(fd1, &stat1) < 0) {
> > + perror("fstat");
> > + return -1;
> > + }
> > + if (fstat(fd2, &stat2) < 0) {
> > + perror("fstat");
> > + return -1;
> > + }
> > + return (stat1.st_dev == stat2.st_dev) && (stat1.st_ino == stat2.st_ino);
> > +}
> > +
> > static int
> > copy_range_f(int argc, char **argv)
> > {
> > @@ -147,10 +160,12 @@ copy_range_f(int argc, char **argv)
> > }
> > len = sz;
> >
> > - ret = copy_dst_truncate();
> > - if (ret < 0) {
> > - ret = 1;
> > - goto out;
> > + if (!is_same_file(fd, file->fd)) {
> > + ret = copy_dst_truncate();
> > + if (ret < 0) {
> > + ret = 1;
> > + goto out;
> > + }
>
> Finally we turn to talk about this part now:) The patch itself looks fine to
> me.
>
> I just have one question to other xfsprogs developers, why the copy_range
> would
> like to truncate(0) the target file by default (len=0 by default)? I think
> this's
> not a same or not same files problem, this's why we truncate the target file?
>
> Why not set the 'len' to the size of srcfile(copy_src_filesize) by default if
> there's not a '-l N' specified? And never truncate the target file (if
> someone need
> to truncate target file, do it by -c 'truncate N' or '-t').
>
> Anyway, talk is cheap, show my demo code to explain what I mean:
>
> diff --git a/io/copy_file_range.c b/io/copy_file_range.c
> index b7b9fd88..51c3dc55 100644
> --- a/io/copy_file_range.c
> +++ b/io/copy_file_range.c
> @@ -66,15 +66,6 @@ copy_src_filesize(int fd)
> return st.st_size;
> }
>
> -static int
> -copy_dst_truncate(void)
> -{
> - int ret = ftruncate(file->fd, 0);
> - if (ret < 0)
> - perror("ftruncate");
> - return ret;
> -}
> -
> static int
> copy_range_f(int argc, char **argv)
> {
> @@ -87,6 +78,7 @@ copy_range_f(int argc, char **argv)
> int src_path_arg = 1;
> int src_file_nr = 0;
> size_t fsblocksize, fssectsize;
> + int lflag=0;
>
> init_cvtnum(&fsblocksize, &fssectsize);
>
> @@ -112,6 +104,7 @@ copy_range_f(int argc, char **argv)
> printf(_("invalid length -- %s\n"), optarg);
> return 0;
> }
> + lflag = 1;
> break;
> case 'f':
> src_file_nr = atoi(argv[1]);
> @@ -137,23 +130,15 @@ copy_range_f(int argc, char **argv)
> fd = filetable[src_file_nr].fd;
> }
>
> - if (src == 0 && dst == 0 && len == 0) {
> + if (!lflag) {
> off64_t sz;
> -
> sz = copy_src_filesize(fd);
> - if (sz < 0 || (unsigned long long)sz > SIZE_MAX) {
> - ret = 1;
> - goto out;
> - }
> - len = sz;
> -
> - ret = copy_dst_truncate();
> - if (ret < 0) {
> + if (sz < 0 || (unsigned long long)sz > SIZE_MAX || sz < src)
> {
> ret = 1;
> goto out;
> }
> + len = sz - src;
> }
> -
> ret = copy_file_range_cmd(fd, &src, &dst, len);
> out:
> close(fd);
>
> Thanks,
> Zorro
>
> > }
> > }
> >
> > --
> > 2.17.2
> >
>
