cmsfs: export extra file attributes via xattr

Signed-off-by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>

diff --git a/fs/cmsfs/xattr.c b/fs/cmsfs/xattr.c
new file mode 100644
index 0000000..df48aed
--- /dev/null
+++ b/fs/cmsfs/xattr.c
@@ -0,0 +1,74 @@
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+
+#include <linux/errno.h>
+
+#include "cmsfs.h"
+
+ssize_t cmsfs_getxattr(struct dentry *dentry, const char *name, void *value,
+		       size_t size)
+{
+	char tmp[16];
+	char *out = NULL;
+
+	if (!strcmp("system.recfm", name)) {
+		switch (CMSFS_I(dentry->d_inode)->recfm) {
+			case RECFM_FIXED:
+				out = "fixed";
+				break;
+			case RECFM_VAR:
+				out = "variable";
+				break;
+			default:
+				out = "???";
+				break;
+		}
+	} else if (!strcmp("system.lrecl", name)) {
+		snprintf(tmp, 16, "%d", CMSFS_I(dentry->d_inode)->lrecl);
+		out = tmp;
+	} else if (!strcmp("system.items", name)) {
+		snprintf(tmp, 16, "%d", CMSFS_I(dentry->d_inode)->items);
+		out = tmp;
+	}
+
+	if (!out)
+		return -ENODATA;
+
+	if (!value && !size)
+		return strlen(out);
+
+	if (size < strlen(out))
+		return -ERANGE;
+
+	strcpy(value, out);
+
+	return strlen(out);
+}
+
+#define ATTRLIST "system.recfm\0system.lrecl\0system.items\0"
+
+ssize_t cmsfs_listxattr(struct dentry *dentry, char *list, size_t size)
+{
+	if (!list || !size)
+		return sizeof(ATTRLIST);
+
+	if (size < sizeof(ATTRLIST))
+		return -ERANGE;
+
+	memcpy(list, ATTRLIST, sizeof(ATTRLIST));
+
+	return sizeof(ATTRLIST);
+}
+
+int cmsfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		   size_t size, int flags)
+{
+	return -EOPNOTSUPP;
+}
+
+int cmsfs_removexattr(struct dentry *dentry, const char *name)
+{
+	return -EOPNOTSUPP;
+}