Re: [PATCH v5 8/9] vfs: Add vfs_copy_file_range() support for pagecache copies

On 2015-10-16 01:38, Christoph Hellwig wrote:

On Thu, Oct 15, 2015 at 08:24:51AM -0400, Austin S Hemmelgarn wrote:

quoted

My only point with saying we shouldn't reflink by default is that there are
many (unintelligent) people who will assume that since the syscall has copy
in it's name, that's what it will do; and, while I don't think we should
cater to such individuals, it does make sense to have a syscall that says in
it's name that it copies data actually do so by default.

As far as the user is concerned a reflink is a copy.  A very efficient
copy.

I should have been specific, what I meant was that some people will 
assume that it actually creates a physical, on-disk byte-for-byte copy 
of the data.  There are many people out there (and sadly I have to deal 
with some at work) who are absolutely terrified of the concept of data 
deduplication, and will likely refuse to use this syscall for _anything_ 
if it reflinks by default on filesystems that support it.