Giuseppe Scrivano wrote: > Hello, > > the BTRFS file system, avaiable on Linux since its 2.6.29 version, > supports file cloning. This simple patch adds the support for this > feature to the cp utility.
Thanks! I like it. A few comments: Doesn't that constant, 1074041865, have a symbolic name? Maybe BTRFS_IOC_CLONE? > Is there an easy and quick way to determine which file system is used by > a file? Probably it would be safer to add a guard around the ioctl > call. Before thinking about that, I'd like to know the approximate cost of the failing ioctl, e.g., on a kernel with btrfs support and on one without, in case that makes a difference. I.e., what impact would it have if left unprotected? Does it make a measurable difference when copying 20K empty files on a tmpfs file system? If necessary, we can avoid almost all of the per-file ioctl calls via a map that associates each distinct device number encountered with a boolean "is btrfs file system". gnulib's fts does something similar, but its goal is to determine whether a different FS-specific performance optimization is likely to help. _______________________________________________ Bug-coreutils mailing list [email protected] http://lists.gnu.org/mailman/listinfo/bug-coreutils
