[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>

1 files changed, 10 insertions, 6 deletions

diff --git a/fs/xfs/linux-2.6/xfs_file.c b/fs/xfs/linux-2.6/xfs_file.c
index 4847eb83fc18..21a1c2b1c5fc 100644
--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/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 */;