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. > --- > fs/ceph/mds_client.c | 8 ++++---- > fs/ceph/super.c | 21 +++++++++++---------- > fs/ceph/super.h | 2 +- > 3 files changed, 16 insertions(+), 15 deletions(-) > > diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c > index 3e792eca6af7..82f63ef2694c 100644 > --- a/fs/ceph/mds_client.c > +++ b/fs/ceph/mds_client.c > @@ -4590,7 +4590,7 @@ void ceph_mdsc_destroy(struct ceph_fs_client *fsc) > void ceph_mdsc_handle_fsmap(struct ceph_mds_client *mdsc, struct ceph_msg *msg) > { > struct ceph_fs_client *fsc = mdsc->fsc; > - const char *mds_namespace = fsc->mount_options->mds_namespace; > + const char *fs_name = fsc->mount_options->fs_name; > void *p = msg->front.iov_base; > void *end = p + msg->front.iov_len; > u32 epoch; > @@ -4634,9 +4634,9 @@ void ceph_mdsc_handle_fsmap(struct ceph_mds_client *mdsc, struct ceph_msg *msg) > namelen = ceph_decode_32(&info_p); > ceph_decode_need(&info_p, info_end, namelen, bad); > > - if (mds_namespace && > - strlen(mds_namespace) == namelen && > - !strncmp(mds_namespace, (char *)info_p, namelen)) { > + if (fs_name && > + strlen(fs_name) == namelen && > + !strncmp(fs_name, (char *)info_p, namelen)) { > mount_fscid = fscid; > break; > } > diff --git a/fs/ceph/super.c b/fs/ceph/super.c > index c7f150686a53..31acb4fe1f2c 100644 > --- a/fs/ceph/super.c > +++ b/fs/ceph/super.c > @@ -140,7 +140,7 @@ enum { > Opt_congestion_kb, > /* int args above */ > Opt_snapdirname, > - Opt_mds_namespace, > + Opt_fs, > Opt_recover_session, > Opt_source, > /* string args above */ > @@ -181,7 +181,8 @@ static const struct fs_parameter_spec ceph_mount_parameters[] = { > fsparam_flag_no ("fsc", Opt_fscache), // fsc|nofsc > fsparam_string ("fsc", Opt_fscache), // fsc=... > fsparam_flag_no ("ino32", Opt_ino32), > - fsparam_string ("mds_namespace", Opt_mds_namespace), > + fsparam_string ("mds_namespace", Opt_fs), // backwards compatibility > + fsparam_string ("fs", Opt_fs), // new alias for mds_namespace > fsparam_flag_no ("poolperm", Opt_poolperm), > fsparam_flag_no ("quotadf", Opt_quotadf), > fsparam_u32 ("rasize", Opt_rasize), > @@ -300,9 +301,9 @@ static int ceph_parse_mount_param(struct fs_context *fc, > fsopt->snapdir_name = param->string; > param->string = NULL; > break; > - case Opt_mds_namespace: > - kfree(fsopt->mds_namespace); > - fsopt->mds_namespace = param->string; > + case Opt_fs: > + kfree(fsopt->fs_name); > + fsopt->fs_name = param->string; > param->string = NULL; > break; > case Opt_recover_session: > @@ -460,7 +461,7 @@ static void destroy_mount_options(struct ceph_mount_options *args) > return; > > kfree(args->snapdir_name); > - kfree(args->mds_namespace); > + kfree(args->fs_name); > kfree(args->server_path); > kfree(args->fscache_uniq); > kfree(args); > @@ -494,7 +495,7 @@ static int compare_mount_options(struct ceph_mount_options *new_fsopt, > if (ret) > return ret; > > - ret = strcmp_null(fsopt1->mds_namespace, fsopt2->mds_namespace); > + ret = strcmp_null(fsopt1->fs_name, fsopt2->fs_name); > if (ret) > return ret; > > @@ -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. > > if (fsopt->flags & CEPH_MOUNT_OPT_CLEANRECOVER) > seq_show_option(m, "recover_session", "clean"); > @@ -643,7 +644,7 @@ static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt, > fsc->client->extra_mon_dispatch = extra_mon_dispatch; > ceph_set_opt(fsc->client, ABORT_ON_FULL); > > - if (!fsopt->mds_namespace) { > + if (!fsopt->fs_name) { > ceph_monc_want_map(&fsc->client->monc, CEPH_SUB_MDSMAP, > 0, true); > } else { > diff --git a/fs/ceph/super.h b/fs/ceph/super.h > index 4b269dc845bb..fc4c125b42fb 100644 > --- a/fs/ceph/super.h > +++ b/fs/ceph/super.h > @@ -90,7 +90,7 @@ struct ceph_mount_options { > */ > > char *snapdir_name; /* default ".snap" */ > - char *mds_namespace; /* default NULL */ > + char *fs_name; /* default NULL */ > char *server_path; /* default NULL (means "/") */ > char *fscache_uniq; /* default NULL */ > }; -- Jeff Layton <jlayton@xxxxxxxxxx>
