Btrfs: unaligned access fixes

Btrfs set/get macros lose type information needed to avoid
unaligned accesses on sparc64.
ere is a patch for the kernel bits which fixes most of the
unaligned accesses on sparc64.

btrfs_name_hash is modified to return the hash value instead
of getting a return location via a (potentially unaligned)
pointer.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 11 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 52144b04f1af..086cb0525cd1 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -495,22 +495,17 @@ void btrfs_set_##name(struct extent_buffer *eb, type *s, u##bits val);
 #define BTRFS_SETGET_HEADER_FUNCS(name, type, member, bits)             \
 static inline u##bits btrfs_##name(struct extent_buffer *eb)            \
 {                                                                       \
-        char *kaddr = kmap_atomic(eb->first_page, KM_USER0);            \
-        unsigned long offset = offsetof(type, member);                  \
-        u##bits res;                                                    \
-        __le##bits *tmp = (__le##bits *)(kaddr + offset);               \
-        res = le##bits##_to_cpu(*tmp);                                  \
-        kunmap_atomic(kaddr, KM_USER0);                                 \
+        type *p = kmap_atomic(eb->first_page, KM_USER0);                \
+        u##bits res = le##bits##_to_cpu(p->member);                     \
+        kunmap_atomic(p, KM_USER0);                                     \
         return res;                                                     \
 }                                                                       \
 static inline void btrfs_set_##name(struct extent_buffer *eb,           \
                                     u##bits val)                        \
 {                                                                       \
-        char *kaddr = kmap_atomic(eb->first_page, KM_USER0);            \
-        unsigned long offset = offsetof(type, member);                  \
-        __le##bits *tmp = (__le##bits *)(kaddr + offset);               \
-        *tmp = cpu_to_le##bits(val);                                    \
-        kunmap_atomic(kaddr, KM_USER0);                                 \
+        type *p = kmap_atomic(eb->first_page, KM_USER0);                \
+        p->member = cpu_to_le##bits(val);                               \
+        kunmap_atomic(p, KM_USER0);                                     \
 }
 
 #define BTRFS_SETGET_STACK_FUNCS(name, type, member, bits)              \