> Hmm, while I see why adding this flag is convenient, it still should be possible > to have an ioctl to open the file and to set the flag? If a wrong panfs-inode > flag is set, failing either the normal- or the ioctl-open would also work. > Cheers, > Bernd Yes, an ioctl open is possible but not ideal. The interface would require an additional open to perform the ioctl against. The open system call is really a great place to pass control information to the filesystem and any other solution seems less elegant. There is also the issue of backward compatibility with existing MPI applications that have been built using the existing O_CONCURRENT_WRITE flag. A user wanting to ensure compatibility would have to consider four pieces of software: the kernel, the filesystem version, the MPI package and finally the application. Having a single flag bit can make a big difference in this regard. Regards, Rodney
