bcachefs: use swab40 for bch_backpointer.bucket_offset bitfield

The bucket_offset field of bch_backpointer is a 40-bit bitfield, but the
bch2_backpointer_swab() helper uses swab32. This leads to inconsistency
when an on-disk fs is accessed from an opposite endian machine.

As it turns out, we already have an internal swab40() helper that is
used from the bch_alloc_v4 swab callback. Lift it into the backpointers
header file and use it consistently in both places.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index ad256a8..1fec0e6 100644 (file)
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -297,15 +297,6 @@ fsck_err:
        return ret;
 }
 
-static inline u64 swab40(u64 x)
-{
-       return (((x & 0x00000000ffULL) << 32)|
-               ((x & 0x000000ff00ULL) << 16)|
-               ((x & 0x0000ff0000ULL) >>  0)|
-               ((x & 0x00ff000000ULL) >> 16)|
-               ((x & 0xff00000000ULL) >> 32));
-}
-
 void bch2_alloc_v4_swab(struct bkey_s k)
 {
        struct bch_alloc_v4 *a = bkey_s_to_alloc_v4(k).v;

diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c
index 3b79bde..5ed96dd 100644 (file)
--- a/fs/bcachefs/backpointers.c
+++ b/fs/bcachefs/backpointers.c
@@ -77,7 +77,7 @@ void bch2_backpointer_swab(struct bkey_s k)
 {
        struct bkey_s_backpointer bp = bkey_s_to_backpointer(k);
 
-       bp.v->bucket_offset     = swab32(bp.v->bucket_offset);
+       bp.v->bucket_offset     = swab40(bp.v->bucket_offset);
        bp.v->bucket_len        = swab32(bp.v->bucket_len);
        bch2_bpos_swab(&bp.v->pos);
 }

diff --git a/fs/bcachefs/backpointers.h b/fs/bcachefs/backpointers.h
index 4ab9f35..ab866fe 100644 (file)
--- a/fs/bcachefs/backpointers.h
+++ b/fs/bcachefs/backpointers.h
@@ -7,6 +7,15 @@
 #include "buckets.h"
 #include "super.h"
 
+static inline u64 swab40(u64 x)
+{
+       return (((x & 0x00000000ffULL) << 32)|
+               ((x & 0x000000ff00ULL) << 16)|
+               ((x & 0x0000ff0000ULL) >>  0)|
+               ((x & 0x00ff000000ULL) >> 16)|
+               ((x & 0xff00000000ULL) >> 32));
+}
+
 int bch2_backpointer_invalid(struct bch_fs *, struct bkey_s_c k,
                             enum bkey_invalid_flags, struct printbuf *);
 void bch2_backpointer_to_text(struct printbuf *, const struct bch_backpointer *);