On 2015-06-30 17:45, Dave Chinner wrote:
> On Tue, Jun 30, 2015 at 09:32:20AM -0700, Omar Sandoval wrote:
>> In some cases, we may not want to enable automatic defragmentation for
>> the whole filesystem with the "autodefrag" mount option but we still
>> want to defragment specific files or directories. Add an inode flag
>> which allows us to do specify that.
>>
>> Signed-off-by: Omar Sandoval <osandov@fb.com>
>> ---
>> Resending this because I didn't send it to fsdevel or linux-api last
>> time and I'm adding a new user-facing inode flag.
>
> XFS has a "no defrag" inode flag to tell the defragmenter not to
> defrag the file. (XFS_XFLAG_NODEFRAG, see xfsctl(3)). With the ext4
> project quota work, this flag and interface is being pulled up to
> the VFS, so perhaps it would be a good idea to turn this around the
> other way?  i.e. autodefrag is the default behaviour, and the inode
> contains an inheritable  "no defrag" flag to prevent defrag so that
> we have the same flag, API and behaviour across filesystems?
>
+! on this suggestion, I find that there are only a few files that I 
don't want autodefrag enabled for, and I do want it on pretty much 
everything else.  Furthermore, userspace API consistency is a Good Thing.