udf: reduce stack usage of udf_get_filename

Allocate strings with kmalloc.

Checkstack output:
Before: udf_get_filename:          600
After:  udf_get_filename:          136

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index 9fdf8c9..a3bbdbd 100644 (file)
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -324,34 +324,43 @@ try_again:
 int udf_get_filename(struct super_block *sb, uint8_t *sname, uint8_t *dname,
                     int flen)
 {
-       struct ustr filename, unifilename;
-       int len;
+       struct ustr *filename, *unifilename;
+       int len = 0;
 
-       if (udf_build_ustr_exact(&unifilename, sname, flen))
+       filename = kmalloc(sizeof(struct ustr), GFP_NOFS);
+       if (!filename)
                return 0;
 
+       unifilename = kmalloc(sizeof(struct ustr), GFP_NOFS);
+       if (!unifilename)
+               goto out1;
+
+       if (udf_build_ustr_exact(unifilename, sname, flen))
+               goto out2;
+
        if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
-               if (!udf_CS0toUTF8(&filename, &unifilename)) {
+               if (!udf_CS0toUTF8(filename, unifilename)) {
                        udf_debug("Failed in udf_get_filename: sname = %s\n",
                                  sname);
-                       return 0;
+                       goto out2;
                }
        } else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {
-               if (!udf_CS0toNLS(UDF_SB(sb)->s_nls_map, &filename,
-                                 &unifilename)) {
+               if (!udf_CS0toNLS(UDF_SB(sb)->s_nls_map, filename,
+                                 unifilename)) {
                        udf_debug("Failed in udf_get_filename: sname = %s\n",
                                  sname);
-                       return 0;
+                       goto out2;
                }
        } else
-               return 0;
-
-       len = udf_translate_to_linux(dname, filename.u_name, filename.u_len,
-                                    unifilename.u_name, unifilename.u_len);
-       if (len)
-               return len;
-
-       return 0;
+               goto out2;
+
+       len = udf_translate_to_linux(dname, filename->u_name, filename->u_len,
+                                    unifilename->u_name, unifilename->u_len);
+out2:
+       kfree(unifilename);
+out1:
+       kfree(filename);
+       return len;
 }
 
 int udf_put_filename(struct super_block *sb, const uint8_t *sname,