This seems like a bug.  My guess is that either status2() shouldn't
return O_TRUNC, or it shouldn't be saved in the fd to begin with.
O_TRUNC is a transitory flag, only useful at the time of the open itself.

Fixing the common status2() is simplest; otherwise we need to fix all
the FSALs.

Daniel

On 10/12/2018 08:12 PM, Pradeep wrote:
> Hello,
>
> I'm seeing an issue with a specific application flow and with ganesha
> server (2.6.5). Here is what the application does:
>
> - fd1 = open (file1, O_WRONLY|O_CREAT|O_TRUNC)
>    Ganesha creates a state and stores the flags in fd->openflags (see
> vfs_open2())
> - write (fd1, ....)
> - fd2 = open(file1, O_RDONLY)
>    Ganesha finds the state for the first open, finds the flags and calls
> fsal_reopen2() with old and new flags OR'd together. This causes the
> file to be truncated because the original open was done with O_TRUNC.
>
> I don't see this behavior with kernel NFS or a local filesystem. Any
> suggestions on fixing this? Here is a quick and dirty program to
> reproduce it - you can see that the second stat prints zero as size with
> a mount from Ganesha server.
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <sys/stat.h>
> #include <unistd.h>
>
> int main(int argc, char **argv)
> {
>    char *fn = argv[1];
>    int fd;
>    char buf[1024];
>    struct stat stbuf;
>    int rc;
>
>
>    fd = open(fn, O_WRONLY|O_CREAT|O_TRUNC, 0666);
>    printf("open(%s) = %d\n", fn, fd);
>
>    ssize_t ret;
>    ret = write(fd, buf, sizeof(buf));
>    printf("write returned %ld\n", ret);
>
>    rc = stat(fn, &stbuf);
>    printf("size: %ld\n", stbuf.st_size);
>
>    int fd1;
>    fd1 = open(fn, O_RDONLY);
>    printf("open(%s) = %d\n", fn, fd1);
>
>    rc = stat(fn, &stbuf);
>    printf("size: %ld\n", stbuf.st_size);
> }
>
> Thanks,
> Pradeep
>
>
>
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