On Tue, Jun 29, 2021 at 5:02 PM Luis Henriques <lhenriques@xxxxxxx> wrote:
>
> [ As I said, I didn't fully reviewed this patch. Just sending out a few
> comments. ]
>
> On Mon, Jun 28, 2021 at 01:25:42PM +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 | 117 +++++++++++++++++++++++++++++++++++++++++++-----
> > fs/ceph/super.h | 3 ++
> > 2 files changed, 110 insertions(+), 10 deletions(-)
> >
> > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> > index 9b1b7f4cfdd4..950a28ad9c59 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 +228,68 @@ 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 != '=')
> > + return invalfc(fc, "separator '=' missing in source");
>
> An annoying thing is that we'll always see this error message when falling
> back to the old_source method.
>
> (Also, is there a good reason for using '=' instead of ':'? I probably
> missed this discussion somewhere else already...)
>
> > +
> > + 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 +322,48 @@ 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;
> >
> > + 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 = kstrdup(param->string, GFP_KERNEL);
> > + if (!fsopt->mon_addr)
> > + return -ENOMEM;
> > +
> > + strreplace(param->string, '/', ',');
> > + r = ceph_parse_mon_ips(param->string, strlen(param->string),
> > + pctx->copts, fc->log.log);
> > + param->string = NULL;
>
> I think this will result in a memory leak. Why don't we simply set
> fsopt->mon_addr to param->string instead of kstrdup'ing it?
Sure. As discussed over irc, will do away with the alloc.
>
> Cheers,
> --
> Luís
>
> > + return r;
> > }
> >
> > static int ceph_parse_mount_param(struct fs_context *fc,
> > @@ -322,6 +408,8 @@ 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 +561,7 @@ 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 +605,10 @@ 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 +664,13 @@ 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);
> >
> > + 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");
> >
> > diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> > index 839e6b0239ee..557348ff3203 100644
> > --- a/fs/ceph/super.h
> > +++ b/fs/ceph/super.h
> > @@ -88,6 +88,8 @@ 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()
> > @@ -97,6 +99,7 @@ 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
> >
>
--
Cheers,
Venky
