tmpfs: Initialize sysfs during tmpfs init

Instead of using fs_initcall(), initialize sysfs with the rest of the
filesystem. This is the right way to do it because otherwise any error
during tmpfs_sysfs_init() would get silently ignored. It's also useful
if tmpfs' sysfs ever need to display runtime information.

Signed-off-by: André Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/r/20241101164251.327884-4-andrealmeid@igalia.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 00ff7ef16dc6e3ea71f66fee30a500fb45dcb537..1389a29a18bf8a8ef023336e62eb61d12b10fa07 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5126,6 +5126,66 @@ static struct file_system_type shmem_fs_type = {
        .fs_flags       = FS_USERNS_MOUNT | FS_ALLOW_IDMAP,
 };
 
+#if defined(CONFIG_SYSFS) && defined(CONFIG_TMPFS)
+
+#define __INIT_KOBJ_ATTR(_name, _mode, _show, _store)                  \
+{                                                                      \
+       .attr   = { .name = __stringify(_name), .mode = _mode },        \
+       .show   = _show,                                                \
+       .store  = _store,                                               \
+}
+
+#define TMPFS_ATTR_W(_name, _store)                            \
+       static struct kobj_attribute tmpfs_attr_##_name =       \
+                       __INIT_KOBJ_ATTR(_name, 0200, NULL, _store)
+
+#define TMPFS_ATTR_RW(_name, _show, _store)                    \
+       static struct kobj_attribute tmpfs_attr_##_name =       \
+                       __INIT_KOBJ_ATTR(_name, 0644, _show, _store)
+
+#define TMPFS_ATTR_RO(_name, _show)                            \
+       static struct kobj_attribute tmpfs_attr_##_name =       \
+                       __INIT_KOBJ_ATTR(_name, 0444, _show, NULL)
+
+#if IS_ENABLED(CONFIG_UNICODE)
+static ssize_t casefold_show(struct kobject *kobj, struct kobj_attribute *a,
+                       char *buf)
+{
+               return sysfs_emit(buf, "supported\n");
+}
+TMPFS_ATTR_RO(casefold, casefold_show);
+#endif
+
+static struct attribute *tmpfs_attributes[] = {
+#if IS_ENABLED(CONFIG_UNICODE)
+       &tmpfs_attr_casefold.attr,
+#endif
+       NULL
+};
+
+static const struct attribute_group tmpfs_attribute_group = {
+       .attrs = tmpfs_attributes,
+       .name = "features"
+};
+
+static struct kobject *tmpfs_kobj;
+
+static int __init tmpfs_sysfs_init(void)
+{
+       int ret;
+
+       tmpfs_kobj = kobject_create_and_add("tmpfs", fs_kobj);
+       if (!tmpfs_kobj)
+               return -ENOMEM;
+
+       ret = sysfs_create_group(tmpfs_kobj, &tmpfs_attribute_group);
+       if (ret)
+               kobject_put(tmpfs_kobj);
+
+       return ret;
+}
+#endif /* CONFIG_SYSFS && CONFIG_TMPFS */
+
 void __init shmem_init(void)
 {
        int error;
@@ -5149,6 +5209,14 @@ void __init shmem_init(void)
                goto out1;
        }
 
+#if defined(CONFIG_SYSFS) && defined(CONFIG_TMPFS)
+       error = tmpfs_sysfs_init();
+       if (error) {
+               pr_err("Could not init tmpfs sysfs\n");
+               goto out1;
+       }
+#endif
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
        if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
                SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
@@ -5546,65 +5614,3 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
        return page;
 }
 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);
-
-#if defined(CONFIG_SYSFS) && defined(CONFIG_TMPFS)
-
-#define __INIT_KOBJ_ATTR(_name, _mode, _show, _store)                  \
-{                                                                      \
-       .attr   = { .name = __stringify(_name), .mode = _mode },        \
-       .show   = _show,                                                \
-       .store  = _store,                                               \
-}
-
-#define TMPFS_ATTR_W(_name, _store)                            \
-       static struct kobj_attribute tmpfs_attr_##_name =       \
-                       __INIT_KOBJ_ATTR(_name, 0200, NULL, _store)
-
-#define TMPFS_ATTR_RW(_name, _show, _store)                    \
-       static struct kobj_attribute tmpfs_attr_##_name =       \
-                       __INIT_KOBJ_ATTR(_name, 0644, _show, _store)
-
-#define TMPFS_ATTR_RO(_name, _show)                            \
-       static struct kobj_attribute tmpfs_attr_##_name =       \
-                       __INIT_KOBJ_ATTR(_name, 0444, _show, NULL)
-
-#if IS_ENABLED(CONFIG_UNICODE)
-static ssize_t casefold_show(struct kobject *kobj, struct kobj_attribute *a,
-                       char *buf)
-{
-               return sysfs_emit(buf, "supported\n");
-}
-TMPFS_ATTR_RO(casefold, casefold_show);
-#endif
-
-static struct attribute *tmpfs_attributes[] = {
-#if IS_ENABLED(CONFIG_UNICODE)
-       &tmpfs_attr_casefold.attr,
-#endif
-       NULL
-};
-
-static const struct attribute_group tmpfs_attribute_group = {
-       .attrs = tmpfs_attributes,
-       .name = "features"
-};
-
-static struct kobject *tmpfs_kobj;
-
-static int __init tmpfs_sysfs_init(void)
-{
-       int ret;
-
-       tmpfs_kobj = kobject_create_and_add("tmpfs", fs_kobj);
-       if (!tmpfs_kobj)
-               return -ENOMEM;
-
-       ret = sysfs_create_group(tmpfs_kobj, &tmpfs_attribute_group);
-       if (ret)
-               kobject_put(tmpfs_kobj);
-
-       return ret;
-}
-
-fs_initcall(tmpfs_sysfs_init);
-#endif /* CONFIG_SYSFS && CONFIG_TMPFS */