On Fri, Nov 22, 2024 at 04:40:31PM +0000, Matthew Wilcox wrote: > On Fri, Nov 22, 2024 at 05:15:47PM +0100, Christoph Hellwig wrote: > > On Fri, Nov 22, 2024 at 01:53:42PM +0100, Jan Kara wrote: > > > Here I'm not so sure. Firstly, since you are an owner this doesn't add any > > > additional practical restriction. Secondly, you are not changing anything > > > on disk, just IO hints in memory... Thirdly, we generally don't require > > > writeable fd even to do file attribute changes (like with fchmod, fchown, > > > etc.). So although the check makes some sense, it seems to be mostly > > > inconsistent with how we treat similar stuff. > > > > As I said I'm not quite convince either, so just doing the first one > > is probably fine. > > We do require FMODE_WRITE to do a dedupe, which isn't exactly the same > but is similar in concept (we're not changing the content of the file; > we're changing how it's laid out on storage). So I think it's reasonable > to require FMODE_WRITE to set the write hints. I tend to agree with Jan. I think the dedupe case is different because you actually use the file to perform a write(-like) operation whereas toggling write hints is just setting an option.
