With my rewrite of fscache and cachefiles: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-iter when a file gets invalidated by the server - and, under some circumstances, modified locally - I have the cache create a temporary file with vfs_tmpfile() that I'd like to just link into place over the old one - but I can't because vfs_link() doesn't allow you to do that. Instead I have to either unlink the old one and then link the new one in or create it elsewhere and rename across. Would it be possible to make linkat() take a flag, say AT_LINK_REPLACE, that causes the target to be replaced and not give EEXIST? Or make it so that rename() can take a tmpfile as the source and replace the target with that. I presume that, either way, this would require journal changes on ext4, xfs and btrfs. Thanks, David
