On Fri, 2021-07-02 at 16:35 +0530, Venky Shankar wrote:
> On Fri, Jul 2, 2021 at 4:08 PM Luis Henriques <lhenriques@xxxxxxx> wrote:
> >
> > On Fri, Jul 02, 2021 at 12:18:18PM +0530, Venky Shankar wrote:
> > > Old mount device syntax (source) has the following problems:
> > >
> > > - mounts to the same cluster but with different fsnames
> > > and/or creds have identical device string which can
> > > confuse xfstests.
> > >
> > > - Userspace mount helper tool resolves monitor addresses
> > > and fill in mon addrs automatically, but that means the
> > > device shown in /proc/mounts is different than what was
> > > used for mounting.
> > >
> > > New device syntax is as follows:
> > >
> > > cephuser@fsid.mycephfs2=/path
> > >
> > > Note, there is no "monitor address" in the device string.
> > > That gets passed in as mount option. This keeps the device
> > > string same when monitor addresses change (on remounts).
> > >
> > > Also note that the userspace mount helper tool is backward
> > > compatible. I.e., the mount helper will fallback to using
> > > old syntax after trying to mount with the new syntax.
> > >
> > > Signed-off-by: Venky Shankar <vshankar@xxxxxxxxxx>
> > > ---
> > > fs/ceph/super.c | 122 ++++++++++++++++++++++++++++++++++++++++++++----
> > > fs/ceph/super.h | 3 ++
> > > 2 files changed, 115 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> > > index 9b1b7f4cfdd4..0b324e43c9f4 100644
> > > --- a/fs/ceph/super.c
> > > +++ b/fs/ceph/super.c
> > > @@ -145,6 +145,7 @@ enum {
> > > Opt_mds_namespace,
> > > Opt_recover_session,
> > > Opt_source,
> > > + Opt_mon_addr,
> > > /* string args above */
> > > Opt_dirstat,
> > > Opt_rbytes,
> > > @@ -196,6 +197,7 @@ static const struct fs_parameter_spec ceph_mount_parameters[] = {
> > > fsparam_u32 ("rsize", Opt_rsize),
> > > fsparam_string ("snapdirname", Opt_snapdirname),
> > > fsparam_string ("source", Opt_source),
> > > + fsparam_string ("mon_addr", Opt_mon_addr),
> > > fsparam_u32 ("wsize", Opt_wsize),
> > > fsparam_flag_no ("wsync", Opt_wsync),
> > > {}
> > > @@ -226,10 +228,70 @@ static void canonicalize_path(char *path)
> > > path[j] = '\0';
> > > }
> > >
> > > +static int ceph_parse_old_source(const char *dev_name, const char *dev_name_end,
> > > + struct fs_context *fc)
> > > +{
> > > + int r;
> > > + struct ceph_parse_opts_ctx *pctx = fc->fs_private;
> > > + struct ceph_mount_options *fsopt = pctx->opts;
> > > +
> > > + if (*dev_name_end != ':')
> > > + return invalfc(fc, "separator ':' missing in source");
> > > +
> > > + r = ceph_parse_mon_ips(dev_name, dev_name_end - dev_name,
> > > + pctx->copts, fc->log.log);
> > > + if (r)
> > > + return r;
> > > +
> > > + fsopt->new_dev_syntax = false;
> > > + return 0;
> > > +}
> > > +
> > > +static int ceph_parse_new_source(const char *dev_name, const char *dev_name_end,
> > > + struct fs_context *fc)
> > > +{
> > > + struct ceph_parse_opts_ctx *pctx = fc->fs_private;
> > > + struct ceph_mount_options *fsopt = pctx->opts;
> > > + char *fsid_start, *fs_name_start;
> > > +
> > > + if (*dev_name_end != '=') {
> > > + dout("separator '=' missing in source");
> > > + return -EINVAL;
> > > + }
> > > +
> > > + fsid_start = strchr(dev_name, '@');
> > > + if (!fsid_start)
> > > + return invalfc(fc, "missing cluster fsid");
> > > + ++fsid_start; /* start of cluster fsid */
> > > +
> > > + fs_name_start = strchr(fsid_start, '.');
> > > + if (!fs_name_start)
> > > + return invalfc(fc, "missing file system name");
> > > +
> > > + ++fs_name_start; /* start of file system name */
> > > + fsopt->mds_namespace = kstrndup(fs_name_start,
> > > + dev_name_end - fs_name_start, GFP_KERNEL);
> > > + if (!fsopt->mds_namespace)
> > > + return -ENOMEM;
> > > + dout("file system (mds namespace) '%s'\n", fsopt->mds_namespace);
> > > +
> > > + fsopt->new_dev_syntax = true;
> > > + return 0;
> > > +}
> > > +
> > > /*
> > > - * Parse the source parameter. Distinguish the server list from the path.
> > > + * Parse the source parameter for new device format. Distinguish the device
> > > + * spec from the path. Try parsing new device format and fallback to old
> > > + * format if needed.
> > > *
> > > - * The source will look like:
> > > + * New device syntax will looks like:
> > > + * <device_spec>=/<path>
> > > + * where
> > > + * <device_spec> is name@fsid.fsname
> > > + * <path> is optional, but if present must begin with '/'
> > > + * (monitor addresses are passed via mount option)
> > > + *
> > > + * Old device syntax is:
> > > * <server_spec>[,<server_spec>...]:[<path>]
> > > * where
> > > * <server_spec> is <ip>[:<port>]
> > > @@ -262,22 +324,48 @@ static int ceph_parse_source(struct fs_parameter *param, struct fs_context *fc)
> > > dev_name_end = dev_name + strlen(dev_name);
> > > }
> > >
> > > - dev_name_end--; /* back up to ':' separator */
> > > - if (dev_name_end < dev_name || *dev_name_end != ':')
> > > - return invalfc(fc, "No path or : separator in source");
> > > + dev_name_end--; /* back up to separator */
> > > + if (dev_name_end < dev_name)
> > > + return invalfc(fc, "path missing in source");
> > >
> > > dout("device name '%.*s'\n", (int)(dev_name_end - dev_name), dev_name);
> > > if (fsopt->server_path)
> > > dout("server path '%s'\n", fsopt->server_path);
> > >
> > > - ret = ceph_parse_mon_ips(param->string, dev_name_end - dev_name,
> > > - pctx->copts, fc->log.log);
> > > + dout("trying new device syntax");
> > > + ret = ceph_parse_new_source(dev_name, dev_name_end, fc);
> > > + if (ret == 0)
> > > + goto done;
> > > +
> > > + dout("trying old device syntax");
> > > + ret = ceph_parse_old_source(dev_name, dev_name_end, fc);
> > > if (ret)
> > > - return ret;
> > > + goto out;
> >
> > Do we really need this goto? My (personal) preference would be to drop
> > this one and simply return. And maybe it's even possible to drop the
> > previous 'goto done' too.
>
> Sure. Just a preference I had.
>
> >
> > > + done:
> > > fc->source = param->string;
> > > param->string = NULL;
> > > - return 0;
> > > + out:
> > > + return ret;
> > > +}
> > > +
> > > +static int ceph_parse_mon_addr(struct fs_parameter *param,
> > > + struct fs_context *fc)
> > > +{
> > > + int r;
> > > + struct ceph_parse_opts_ctx *pctx = fc->fs_private;
> > > + struct ceph_mount_options *fsopt = pctx->opts;
> > > +
> > > + kfree(fsopt->mon_addr);
> > > + fsopt->mon_addr = param->string;
> > > + param->string = NULL;
> > > +
> > > + strreplace(fsopt->mon_addr, '/', ',');
> > > + r = ceph_parse_mon_ips(fsopt->mon_addr, strlen(fsopt->mon_addr),
> > > + pctx->copts, fc->log.log);
> > > + // since its used in ceph_show_options()
> >
> > (nit: use c-style comments...? yeah, again personal preference :-)
> >
> > > + strreplace(fsopt->mon_addr, ',', '/');
> >
> > This is ugly. Have you considered modifying ceph_parse_mon_ips() (and
> > ceph_parse_ips()) to receive a delimiter as a parameter?''
>
> I did. However, for most cases (all possibly), "," is the addr
> delimiter. So, I didn't take the approach to make these helpers really
> generic for parsing addrs.
>
Yeah, I'm not a fan of this either. Why not just add an extra char
argument to to ceph_parse_mon_ips and use that to pass in a delimiter
char? Looks like you'll have to plumb it through a couple of functions
but that seems doable.
> >
> > > + return r;
> > > }
> > >
> > > static int ceph_parse_mount_param(struct fs_context *fc,
> > > @@ -322,6 +410,8 @@ static int ceph_parse_mount_param(struct fs_context *fc,
> > > if (fc->source)
> > > return invalfc(fc, "Multiple sources specified");
> > > return ceph_parse_source(param, fc);
> > > + case Opt_mon_addr:
> > > + return ceph_parse_mon_addr(param, fc);
> > > case Opt_wsize:
> > > if (result.uint_32 < PAGE_SIZE ||
> > > result.uint_32 > CEPH_MAX_WRITE_SIZE)
> > > @@ -473,6 +563,7 @@ static void destroy_mount_options(struct ceph_mount_options *args)
> > > kfree(args->mds_namespace);
> > > kfree(args->server_path);
> > > kfree(args->fscache_uniq);
> > > + kfree(args->mon_addr);
> > > kfree(args);
> > > }
> > >
> > > @@ -516,6 +607,10 @@ static int compare_mount_options(struct ceph_mount_options *new_fsopt,
> > > if (ret)
> > > return ret;
> > >
> > > + ret = strcmp_null(fsopt1->mon_addr, fsopt2->mon_addr);
> > > + if (ret)
> > > + return ret;
> > > +
> > > return ceph_compare_options(new_opt, fsc->client);
> > > }
> > >
> > > @@ -571,9 +666,13 @@ 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)
> > > + /* dump mds_namespace when old device syntax is in use */
> > > + if (fsopt->mds_namespace && !fsopt->new_dev_syntax)
> > > seq_show_option(m, "mds_namespace", fsopt->mds_namespace);
> >
> > I haven't really tested it, but... what happens if we set mds_namespace
> > *and* we're using the new syntax? Or, in another words, what should
> > happen?
Probably best to just throw an error at mount time if they don't match.
>
> Depends on the order of token parsing in ceph_parse_mount_param()
> which mds_namespace gets used.
>
> (however, that means ceph_parse_new_source() should additionally
> kfree(fsopt->mds_namespace)).
>
>
> > Cheers,
> > --
> > Luís
> >
> > >
> > > + if (fsopt->mon_addr)
> > > + seq_printf(m, ",mon_addr=%s", fsopt->mon_addr);
> > > +
> > > if (fsopt->flags & CEPH_MOUNT_OPT_CLEANRECOVER)
> > > seq_show_option(m, "recover_session", "clean");
> > >
> > > @@ -1048,6 +1147,7 @@ static int ceph_setup_bdi(struct super_block *sb, struct ceph_fs_client *fsc)
> > > static int ceph_get_tree(struct fs_context *fc)
> > > {
> > > struct ceph_parse_opts_ctx *pctx = fc->fs_private;
> > > + struct ceph_mount_options *fsopt = pctx->opts;
> > > struct super_block *sb;
> > > struct ceph_fs_client *fsc;
> > > struct dentry *res;
> > > @@ -1059,6 +1159,8 @@ static int ceph_get_tree(struct fs_context *fc)
> > >
> > > if (!fc->source)
> > > return invalfc(fc, "No source");
> > > + if (fsopt->new_dev_syntax && !fsopt->mon_addr)
> > > + return invalfc(fc, "No monitor address");
> > >
> > > /* create client (which we may/may not use) */
> > > fsc = create_fs_client(pctx->opts, pctx->copts);
> > > diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> > > index c48bb30c8d70..8f71184b7c85 100644
> > > --- a/fs/ceph/super.h
> > > +++ b/fs/ceph/super.h
> > > @@ -87,6 +87,8 @@ struct ceph_mount_options {
> > > unsigned int max_readdir; /* max readdir result (entries) */
> > > unsigned int max_readdir_bytes; /* max readdir result (bytes) */
> > >
> > > + bool new_dev_syntax;
> > > +
> > > /*
> > > * everything above this point can be memcmp'd; everything below
> > > * is handled in compare_mount_options()
> > > @@ -96,6 +98,7 @@ struct ceph_mount_options {
> > > char *mds_namespace; /* default NULL */
> > > char *server_path; /* default NULL (means "/") */
> > > char *fscache_uniq; /* default NULL */
> > > + char *mon_addr;
> > > };
> > >
> > > struct ceph_fs_client {
> > > --
> > > 2.27.0
> > >
> >
>
>
--
Jeff Layton <jlayton@xxxxxxxxxx>
