Am Dienstag, 13. Oktober 2015, 12:39:12 CET schrieben Sie: > Hi! > > With BTRFS to XFS/Ext4 the inode number of the target file stays the same in > with both cp and mv case (/mnt/zeit is a freshly created XFS in this example): > > merkaba:~> ls -li foo /mnt/zeit/moo > 6609270 foo > 99 /mnt/zeit/moo > merkaba:~> cp foo /mnt/zeit/moo > merkaba:~> ls -li foo /mnt/zeit/moo > 6609270 8 foo > 99 /mnt/zeit/moo > merkaba:~> cp -p foo /mnt/zeit/moo > merkaba:~> ls -li foo /mnt/zeit/moo > 6609270 foo > 99 /mnt/zeit/moo > merkaba:~> mv foo /mnt/zeit/moo > merkaba:~> ls -lid /mnt/zeit/moo > 99 -rw-r--r-- 1 root root 6 Okt 13 12:28 /mnt/zeit/moo > > > With BTRFS as target filesystem however in the mv case I get a new inode: > > merkaba:~> ls -li foo /home/moo > 6609289 -rw-r--r-- 1 root root 6 Okt 13 12:34 foo > 16476276 -rw-r--r-- 1 root root 6 Okt 13 12:34 /home/moo > merkaba:~> cp foo /home/moo > merkaba:~> ls -li foo /home/moo > 6609289 -rw-r--r-- 1 root root 6 Okt 13 12:34 foo > 16476276 -rw-r--r-- 1 root root 6 Okt 13 12:34 /home/moo > merkaba:~> cp -p foo /home/moo > merkaba:~> ls -li foo /home/moo > 6609289 -rw-r--r-- 1 root root 6 Okt 13 12:34 foo > 16476276 -rw-r--r-- 1 root root 6 Okt 13 12:34 /home/moo > merkaba:~> mv foo /home/moo > merkaba:~> ls -li /home/moo > 16476280 -rw-r--r-- 1 root root 6 Okt 13 12:34 /home/moo > > > Is this intentional and/or somehow related to the copy on write specifics of > the filesystem? > > I think even with COW it can just overwrite the existing file instead of > removing the old one and creating a new one – but it wouldn´t give much of a > benefit unless the target file is nocow. > > (Also I thought only certain other utilities had supercow powers, but well > BTRFS seems to have them as well :)
Anyone any idea? Thanks, -- Martin -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
