[XFS] fix unaligned access in readdir

This patch should fix the issue seen on Alpha with unaligned accesses in
the new readdir code. By aligning each dirent to sizeof(u64) we'll avoid
unaligned accesses. To make doubly sure we're not hitting problems also
rearrange struct hack_dirent to avoid holes.

SGI-PV: 975411
SGI-Modid: xfs-linux-melb:xfs-kern:30302a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

fs/xfs/linux-2.6/xfs_file.c

@@ -261,9 +261,9 @@ xfs_file_readdir(
 #else
 
 struct hack_dirent {
-	int		namlen;
-	loff_t		offset;
 	u64		ino;
+	loff_t		offset;
+	int		namlen;
 	unsigned int	d_type;
 	char		name[];
 };
@@ -285,8 +285,10 @@ xfs_hack_filldir(
 {
 	struct hack_callback *buf = __buf;
 	struct hack_dirent *de = (struct hack_dirent *)(buf->dirent + buf->used);
+	unsigned int reclen;
 
-	if (buf->used + sizeof(struct hack_dirent) + namlen > buf->len)
+	reclen = ALIGN(sizeof(struct hack_dirent) + namlen, sizeof(u64));
+	if (buf->used + reclen > buf->len)
 		return -EINVAL;
 
 	de->namlen = namlen;
@@ -294,7 +296,7 @@ xfs_hack_filldir(
 	de->ino = ino;
 	de->d_type = d_type;
 	memcpy(de->name, name, namlen);
-	buf->used += sizeof(struct hack_dirent) + namlen;
+	buf->used += reclen;
 	return 0;
 }
 
@@ -334,7 +336,8 @@ xfs_file_readdir(
 		offset = filp->f_pos;
 
 	while (!eof) {
-		int reclen;
+		unsigned int reclen;
+
 		start_offset = offset;
 
 		buf.used = 0;
@@ -355,7 +358,8 @@ xfs_file_readdir(
 				goto done;
 			}
 
-			reclen = sizeof(struct hack_dirent) + de->namlen;
+			reclen = ALIGN(sizeof(struct hack_dirent) + de->namlen,
+				       sizeof(u64));
 			size -= reclen;
 			de = (struct hack_dirent *)((char *)de + reclen);
 			curr_offset = de->offset /* & 0x7fffffff */;