On Thu, Jul 12, 2018 at 2:57 PM cgxu519 <cgxu519@xxxxxxx> wrote: > > On 07/12/2018 05:37 PM, John Spray wrote: > > On Thu, Jul 12, 2018 at 7:38 AM Chengguang Xu <cgxu519@xxxxxxx> wrote: > >> Hi guys, > >> > >> Currently, we can arbitrarily change max file size in cephfs if the size is just larger than 65536. > >> Could we change it to only allowing increment? It seems there is no good reason to decrease the size. > >> What do you think? > > If we made increases irreversible, then it would be a bit "scary" for > > people to modify the setting at all -- it feels more user friendly to > > let people change it both ways so that they can correct their mistake > > if they set it too high. > > > > While it's a bit annoying that someone can set a max_file_size that is > > really smaller than their largest file, I think it's still useful to > > be able to limit the size of new files. We just need to make sure > > it's clear to users that this is the maximum size for new files rather > > than the actual largest file that exists. > > One thing that I concern is when max_file_size is smaller than some existing > files then we probably cannot operate(read/write) exceeded data range. > Because sanity check will adjust real read/write size or even return > error directly > when offset larger than max_file_size. So it looks like a kind of > truncation and > maybe in some cases applications think the file is incomplete. I haven't looked in detail, but hopefully we could fix that so that the max_filesize() check is only enforced when exceeding the current size of the file. I agree that blocking overwrites in an existing big file is a weird behaviour. John > > It would be better to record largest file size and do not allow setting > max_file_size > smaller than that but I'm not so sure if it is worth the complexity. > > Thanks, > Chengguang > > > > > > > > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
