On Thu, 24 Jun 2010, Nick Piggin wrote: > This has come up a few times in the past, and I'd like to try to get > an agreement on it. statvfs(2) importantly contains f_flag (mount > flags), and is encouraged to use rather than statfs(2). The kernel > provides a statfs syscall only. > > This means glibc has to provide f_flag support by parsing /proc/mounts > and stat(2)ing mount points. This is really slow, and /proc/mounts is > hard for the kernel to provide. It's actually the last scalability > bottleneck in the core vfs for dbench (samba) after my patches. > > Not only that, but it's racy. > > Other than types, other differences are: > - statvfs(2) has is f_frsize, which seems fairly useless. statfs(2) also has f_frsize since 2.6.0, only it hasn't been documented (should be fixed now). > - statvfs(2) has f_favail. > - statfs(2) f_bsize is optimal transfer block, statvfs(2) f_bsize is fs > block size. The latter could be useful for disk space algorithms. > Both can be ill defned. They are the same, only the documentation is different. > - statvfs(2) lacks f_type. > > Is there anything more we should add here? Samba wants a capabilities > field, with things like sparse files, quotas, compression, encryption, > case preserving/sensitive. > > Any thoughts? "struct statfs" and "struct statfs64" have spare fields. We could put the f_flag in there including a magic "this is a valid f_flag" flag, that distinguishes from the default zero value. Thanks, Miklos -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
