On Mon, 2020-02-24 at 10:41 +0800, Xiubo Li wrote: > On 2020/2/23 22:56, Jeff Layton wrote: > > On Sat, 2020-02-22 at 21:14 -0500, xiubli@xxxxxxxxxx wrote: > > > From: Xiubo Li <xiubli@xxxxxxxxxx> > > > > > > The 'fs' here will be cleaner when specifying the ceph fs name, > > > and we can easily get the corresponding name from the `ceph fs > > > dump`: > > > > > > [...] > > > Filesystem 'a' (1) > > > fs_name a > > > epoch 12 > > > flags 12 > > > [...] > > > > > > The 'fs' here just an alias name for 'mds_namespace' mount options, > > > and we will keep 'mds_namespace' for backwards compatibility. > > > > > > URL: https://tracker.ceph.com/issues/44214 > > > Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx> > > It looks like mds_namespace feature went into the kernel in 2016 (in > > v4.7). We're at v5.5 today, so that's a large swath of kernels in the > > field that only support the old option. > > > > While I agree that 'fs=' would have been cleaner and more user-friendly, > > I've found that it's just not worth it to add mount option aliases like > > this unless you have a really good reason. It all ends up being a huge > > amount of churn for little benefit. > > > > The problem with changing it after the fact like this is that you still > > have to support both options forever. Removing support isn't worth the > > pain as you can break working environments. When working environments > > upgrade they won't change to use the new option (why bother?) > > > > Maybe it would be good to start this change by doing a "fs=" to > > "mds_namespace=" translation in the mount helper? That would make the > > new option work across older kernel releases too, and make it simpler to > > document what options are supported. > > This sounds a pretty good idea for me. > > > > > @@ -561,8 +562,8 @@ static int ceph_show_options(struct seq_file *m, struct dentry *root) > > > if ((fsopt->flags & CEPH_MOUNT_OPT_NOCOPYFROM) == 0) > > > seq_puts(m, ",copyfrom"); > > > > > > - if (fsopt->mds_namespace) > > > - seq_show_option(m, "mds_namespace", fsopt->mds_namespace); > > > + if (fsopt->fs_name) > > > + seq_show_option(m, "fs", fsopt->fs_name); > > Someone will mount with mds_namespace= but then that will be converted > > to fs= when displaying options here. It's not necessarily a problem but > > it may be noticed by some users. > > Yeah, but if we convert 'fs=' to 'mds_namespace=' in userland and here > it will always showing with 'mds_namespace=', won't it be the same issue? > > Or should we covert it to "fs/mds_namespace=" here ? Will it make sense ? > Now that I think about it more, it's probably not a problem either way, but we should probably convert it to read 'fs=' here since that's what we're planning to encourage people to use long-term. -- Jeff Layton <jlayton@xxxxxxxxxx>
