> No. If you want new flags bits, make a public proposal. Maybe some other > filesystem would also benefit from them. Ah, I see what you mean now, thanks. I would like to propose O_CONCURRENT_WRITE as a new open flag. It is currently used in the Panasas filesystem (panfs) and defined with value: #define O_CONCURRENT_WRITE 020000000000 This flag has been provided by panfs to HPC users via the mpich package for well over a decade. See: https://github.com/pmodels/mpich/blob/master/src/mpi/romio/adio/ad_panfs/ad_panfs_open6.c#L344 O_CONCURRENT_WRITE indicates to the filesystem that the application doing the open is participating in a coordinated distributed manner with other such applications, possibly running on different hosts. This allows the panfs filesystem to delegate some of the cache coherency responsibilities to the application, improving performance. The reason this flag is used on open as opposed to having a post-open ioctl or fcntl SETFL is to allow panfs to catch and reject opens by applications that attempt to access files that have already been opened by applications that have set O_CONCURRENT_WRITE. Recent changes to reject non-VALID_OPEN_FLAGS now prevent this facility from working, so getting our flag bit back would help tremendously. Thank you! Regards, Rodney Fu
