cp --reflink with Btrfs

Quoted 5 lines · Li Dongyang

Have a look at line 998, ioctl.c, inside btrfs_ioctl_clone(),
the src->i_size(the size of the testfile created by touch) is just 0, and this will cause btrfs_ioctl_clone just return -EINVAL.
I'm not sure if it makes sense to clone a file which actually doesn't have any data extents.

Probably not, but it seems more consistent to return success instead than -EINVAL. Requiring the caller to check and special case empty files isn't very friendly...

Quoted 11 lines · * Sage Weil ([email protected]) [091216 17:55]:

Quoted 5 lines · Li Dongyang

Have a look at line 998, ioctl.c, inside btrfs_ioctl_clone(),
the src->i_size(the size of the testfile created by touch) is just 0, and this will cause btrfs_ioctl_clone just return -EINVAL.
I'm not sure if it makes sense to clone a file which actually doesn't have any data extents.

Probably not, but it seems more consistent to return success instead than -EINVAL. Requiring the caller to check and special case empty files isn't very friendly...

Actually it makes lots of sense if trying to e.g. cow-copy an chroot on an buildd, and there are some empty files inside of the linux installation (which normally just are).

Can I hope on getting the patch (or another patch) incorporated into the kernel?