is changed. This is only applicable if all lower/upper/work directories are on
the same filesystem, otherwise it will fallback to normal behaviour.
+
+UUID and fsid
+-------------
+
+The UUID of overlayfs instance itself and the fsid reported by statfs(2) are
+controlled by the "uuid" mount option, which supports these values:
+
+- "null": (default)
+ UUID of overlayfs is null. fsid is taken from upper most filesystem.
+- "off":
+ UUID of overlayfs is null. fsid is taken from upper most filesystem.
+ UUID of underlying layers is ignored.
+- "on":
+ UUID of overlayfs is generated and used to report a unique fsid.
+
+
Volatile mount
--------------
* layer where file handle will be decoded.
* In case of uuid=off option just make sure that stored uuid is null.
*/
- if (ofs->config.uuid ? !uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid) :
- !uuid_is_null(&fh->fb.uuid))
+ if (ovl_origin_uuid(ofs) ?
+ !uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid) :
+ !uuid_is_null(&fh->fb.uuid))
return NULL;
bytes = (fh->fb.len - offsetof(struct ovl_fb, fid));
{}
};
+static const struct constant_table ovl_parameter_uuid[] = {
+ { "off", OVL_UUID_OFF },
+ { "null", OVL_UUID_NULL },
+ { "on", OVL_UUID_ON },
+ {}
+};
+
+static const char *ovl_uuid_mode(struct ovl_config *config)
+{
+ return ovl_parameter_uuid[config->uuid].name;
+}
+
+static int ovl_uuid_def(void)
+{
+ return OVL_UUID_NULL;
+}
+
static const struct constant_table ovl_parameter_xino[] = {
{ "off", OVL_XINO_OFF },
{ "auto", OVL_XINO_AUTO },
fsparam_flag("default_permissions", Opt_default_permissions),
fsparam_enum("redirect_dir", Opt_redirect_dir, ovl_parameter_redirect_dir),
fsparam_enum("index", Opt_index, ovl_parameter_bool),
- fsparam_enum("uuid", Opt_uuid, ovl_parameter_bool),
+ fsparam_enum("uuid", Opt_uuid, ovl_parameter_uuid),
fsparam_enum("nfs_export", Opt_nfs_export, ovl_parameter_bool),
fsparam_flag("userxattr", Opt_userxattr),
fsparam_enum("xino", Opt_xino, ovl_parameter_xino),
ofs->config.redirect_mode = ovl_redirect_mode_def();
ofs->config.index = ovl_index_def;
- ofs->config.uuid = true;
+ ofs->config.uuid = ovl_uuid_def();
ofs->config.nfs_export = ovl_nfs_export_def;
ofs->config.xino = ovl_xino_def();
ofs->config.metacopy = ovl_metacopy_def;
ovl_redirect_mode(&ofs->config));
if (ofs->config.index != ovl_index_def)
seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
- if (!ofs->config.uuid)
- seq_puts(m, ",uuid=off");
+ if (ofs->config.uuid != ovl_uuid_def())
+ seq_printf(m, ",uuid=%s", ovl_uuid_mode(&ofs->config));
if (ofs->config.nfs_export != ovl_nfs_export_def)
seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
"on" : "off");
*/
static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
{
- struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
- struct dentry *root_dentry = dentry->d_sb->s_root;
+ struct super_block *sb = dentry->d_sb;
+ struct ovl_fs *ofs = OVL_FS(sb);
+ struct dentry *root_dentry = sb->s_root;
struct path path;
int err;
if (!err) {
buf->f_namelen = ofs->namelen;
buf->f_type = OVERLAYFS_SUPER_MAGIC;
+ if (ovl_has_fsid(ofs))
+ buf->f_fsid = uuid_to_fsid(sb->s_uuid.b);
}
return err;
if (!ovl_upper_mnt(ofs))
sb->s_flags |= SB_RDONLY;
- if (!ofs->config.uuid && ofs->numfs > 1) {
- pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=on.\n");
- ofs->config.uuid = true;
+ if (!ovl_origin_uuid(ofs) && ofs->numfs > 1) {
+ pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=null.\n");
+ ofs->config.uuid = OVL_UUID_NULL;
+ } else if (ovl_has_fsid(ofs)) {
+ /* Use per instance uuid/fsid */
+ uuid_gen(&sb->s_uuid);
}
if (!ovl_force_readonly(ofs) && ofs->config.index) {