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>

1 files changed, 25 insertions, 16 deletions

diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index 9fdf8c93c58e..a3bbdbde9f4b 100644
--- 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,