cifs: convert case-insensitive dentry ops to use new case conversion routines

Have the case-insensitive d_compare and d_hash routines convert each
character in the filenames to wchar_t's and then use the new
cifs_toupper routine to convert those into uppercase.

With this scheme we should more closely emulate the case conversion that
the servers will do.

Reported-and-Tested-by: Jan-Marek Glogowski <[e-mail]>
Signed-off-by: Jeff Layton <[e-mail]>
Signed-off-by: Steve French <[e-mail]>

fs/cifs/dir.c

···
 #include "cifsproto.h"
 #include "cifs_debug.h"
 #include "cifs_fs_sb.h"
+#include "cifs_unicode.h"
 
 static void
 renew_parental_timestamps(struct dentry *direntry)
···
 {
 	struct nls_table *codepage = CIFS_SB(dentry->d_sb)->local_nls;
 	unsigned long hash;
-	int i;
+	wchar_t c;
+	int i, charlen;
 
 	hash = init_name_hash();
-	for (i = 0; i < q->len; i++)
-		hash = partial_name_hash(nls_tolower(codepage, q->name[i]),
-					 hash);
+	for (i = 0; i < q->len; i += charlen) {
+		charlen = codepage->char2uni(&q->name[i], q->len - i, &c);
+		/* error out if we can't convert the character */
+		if (unlikely(charlen < 0))
+			return charlen;
+		hash = partial_name_hash(cifs_toupper(c), hash);
+	}
 	q->hash = end_name_hash(hash);
 
 	return 0;
···
 		unsigned int len, const char *str, const struct qstr *name)
 {
 	struct nls_table *codepage = CIFS_SB(parent->d_sb)->local_nls;
+	wchar_t c1, c2;
+	int i, l1, l2;
 
-	if ((name->len == len) &&
-	    (nls_strnicmp(codepage, name->name, str, len) == 0))
-		return 0;
-	return 1;
+	/*
+	 * We make the assumption here that uppercase characters in the local
+	 * codepage are always the same length as their lowercase counterparts.
+	 *
+	 * If that's ever not the case, then this will fail to match it.
+	 */
+	if (name->len != len)
+		return 1;
+
+	for (i = 0; i < len; i += l1) {
+		/* Convert characters in both strings to UTF-16. */
+		l1 = codepage->char2uni(&str[i], len - i, &c1);
+		l2 = codepage->char2uni(&name->name[i], name->len - i, &c2);
+
+		/*
+		 * If we can't convert either character, just declare it to
+		 * be 1 byte long and compare the original byte.
+		 */
+		if (unlikely(l1 < 0 && l2 < 0)) {
+			if (str[i] != name->name[i])
+				return 1;
+			l1 = 1;
+			continue;
+		}
+
+		/*
+		 * Here, we again ass|u|me that upper/lowercase versions of
+		 * a character are the same length in the local NLS.
+		 */
+		if (l1 != l2)
+			return 1;
+
+		/* Now compare uppercase versions of these characters */
+		if (cifs_toupper(c1) != cifs_toupper(c2))
+			return 1;
+	}
+
+	return 0;
 }
 
 const struct dentry_operations cifs_ci_dentry_ops = {