STINNER Victor <vstin...@redhat.com> added the comment:
> This initial patch provides a callback=None parameter in case the CoW > operation fails because not supported by the underlying filesystems but this > is debatable because we can get different errors depending on the platform > (which is not good). As such a more generic ReflinkNotSupportedError > exception is probably a better choice. (Oh, my laptop only uses btrfs. Hum, I created a loop device to test an ext4 partition :-)) On an ext4 partition, cp --reflink simply fails with an error: it doesn't fallback on a regular copy. vstinner@apu$ dd if=/dev/urandom of=urandom bs=1k count=1k 1024+0 records in 1024+0 records out 1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.0123142 s, 85.2 MB/s vstinner@apu$ cp --reflink urandom urandom2 'urandom' -> 'urandom2' cp: failed to clone 'urandom2' from 'urandom': Operation not supported vstinner@apu$ file urandom2 urandom2: empty vstinner@apu$ stat urandom2 File: urandom2 Size: 0 Blocks: 2 IO Block: 1024 regular empty file Device: 700h/1792d Inode: 13 Links: 1 Access: (0664/-rw-rw-r--) Uid: ( 1000/vstinner) Gid: ( 1000/vstinner) Context: unconfined_u:object_r:unlabeled_t:s0 Access: 2019-06-05 12:08:23.000000000 +0200 Modify: 2019-06-05 12:08:23.000000000 +0200 Change: 2019-06-05 12:08:23.000000000 +0200 Birth: - Not only it fails, but it leaves an empty file. I suggest to mimick the Linux cp command: don't automatically fallback (there are too many error conditions, too many risks of raising a new error while handling the previous error) and don't try to remove the created empty file if reflink() fails. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue37157> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
