tmpfs: Expose filesystem features via sysfs
Expose filesystem features through sysfs, so userspace can query if
tmpfs support casefold.
This follows the same setup as defined by ext4 and f2fs to expose
casefold support to userspace.
Signed-off-by: André Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/r/20241021-tonyk-tmpfs-v8-8-f443d5814194@igalia.com
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
diff --git a/mm/shmem.c b/mm/shmem.c
index ea01628..0739143 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5546,3 +5546,40 @@
return page;
}
EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);
+
+#if defined(CONFIG_SYSFS) && defined(CONFIG_TMPFS)
+#if IS_ENABLED(CONFIG_UNICODE)
+static DEVICE_STRING_ATTR_RO(casefold, 0444, "supported");
+#endif
+
+static struct attribute *tmpfs_attributes[] = {
+#if IS_ENABLED(CONFIG_UNICODE)
+ &dev_attr_casefold.attr.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 */
