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[v7,8/9] tmpfs: Expose filesystem features via sysfs

Message ID 20241017-tonyk-tmpfs-v7-8-a9c056f8391f@igalia.com
State New
Headers show
Series tmpfs: Add case-insensitive support for tmpfs | expand

Commit Message

André Almeida Oct. 17, 2024, 9:14 p.m. UTC 
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>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
 mm/shmem.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
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Patch

diff --git a/mm/shmem.c b/mm/shmem.c
index 8d206e492e7d51dad4bfe1b36426e0064b612dad..7bd7ca5777af70c5a226daa20970781c638e34ef 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5543,3 +5543,40 @@  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)
+#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 */