On Wed, May 29, 2019 at 5:46 PM Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote:
>
> On Wed, May 29, 2019 at 01:13:30PM +0300, Amir Goldstein wrote:
> > Commit 1a05efba ("io: open pipes in non-blocking mode")
> > addressed a specific copy_range issue with pipes by always opening
> > pipes in non-blocking mode.
> >
> > This change takes a different approach and allows passing any
> > open file as the source file to copy_range. Besides providing
> > more flexibility to the copy_range command, this allows xfstests
> > to check if xfs_io supports passing an open file to copy_range.
> >
> > The intended usage is:
> > $ mkfifo fifo
> > $ xfs_io -f -n -r -c "open -f dst" -C "copy_range -f 0" fifo
> >
> > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> > ---
> >
> > Darrick,
> >
> > Folowing our discussion on the copy_range bounds test [1],
> > what do you think about using copy_range -f in the copy_range
> > fifo test with a fifo that was explicitly opened non-blocking,
> > instead of trying to figure out if copy_range is going to hang
> > or not?
> >
> > This option is already available with sendfile command and
> > we can make it available for reflink and dedupe commands if
> > we want to. Too bad that these 4 commands have 3 different
> > usage patterns to begin with...
>
> I wonder if there's any sane way to overload the src_file argument such
> that we can pass filetable[] offsets without having to burn more getopt
> flags...?
>
> (Oh wait, I bet you're using the '-f' flag to figure out if xfs_io is
> new enough not to block on fifos, right? :))
Yes, but this time it is not a hack its a feature..
>
> But otherwise this seems like a reasonable approach.
>
> > Thanks,
> > Amir.
> >
> > [1] https://marc.info/?l=fstests&m=155910786017989&w=2
> >
> > io/copy_file_range.c | 30 ++++++++++++++++++++++++------
> > man/man8/xfs_io.8 | 10 +++++++---
> > 2 files changed, 31 insertions(+), 9 deletions(-)
> >
> > diff --git a/io/copy_file_range.c b/io/copy_file_range.c
> > index d069e5bb..1f0d2713 100644
> > --- a/io/copy_file_range.c
> > +++ b/io/copy_file_range.c
> > @@ -26,6 +26,8 @@ copy_range_help(void)
> > file at offset 200\n\
> > 'copy_range some_file' - copies all bytes from some_file into the open file\n\
> > 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\
> > "));
> > }
> >
> > @@ -82,11 +84,12 @@ copy_range_f(int argc, char **argv)
> > int opt;
> > int ret;
> > int fd;
> > + int src_file_arg = 1;
> > size_t fsblocksize, fssectsize;
> >
> > init_cvtnum(&fsblocksize, &fssectsize);
> >
> > - while ((opt = getopt(argc, argv, "s:d:l:")) != -1) {
> > + while ((opt = getopt(argc, argv, "s:d:l:f:")) != -1) {
> > switch (opt) {
> > case 's':
> > src = cvtnum(fsblocksize, fssectsize, optarg);
> > @@ -109,15 +112,30 @@ copy_range_f(int argc, char **argv)
> > return 0;
> > }
> > break;
> > + case 'f':
> > + fd = atoi(argv[1]);
> > + if (fd < 0 || fd >= filecount) {
> > + printf(_("value %d is out of range (0-%d)\n"),
> > + fd, filecount-1);
> > + return 0;
> > + }
> > + fd = filetable[fd].fd;
> > + /* Expect no src_file arg */
> > + src_file_arg = 0;
> > + break;
> > }
> > }
> >
> > - if (optind != argc - 1)
> > + if (optind != argc - src_file_arg) {
> > + fprintf(stderr, "optind=%d, argc=%d, src_file_arg=%d\n", optind, argc, src_file_arg);
> > return command_usage(©_range_cmd);
> > + }
> >
> > - fd = openfile(argv[optind], NULL, IO_READONLY, 0, NULL);
> > - if (fd < 0)
> > - return 0;
> > + if (src_file_arg) {
>
> I wonder if it would be easier to declare "int fd = -1" and the only do
> the openfile here if fd < 0?
>
I started out with if (fd == -1), but I changed to src_file_arg to
unify the condition for (optind != argc - src_file_arg)
and avoid another condition (i.e. argc - (fd == -1 ? 1 : 0))
Thanks,
Amir.
