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 <[email protected]> --- Here's another one I just tacked on that seems to address the backpointer related problems when switching CPU byte order... Brian fs/bcachefs/alloc_background.c | 9 --------- fs/bcachefs/backpointers.c | 2 +- fs/bcachefs/backpointers.h | 9 +++++++++ 3 files changed, 10 insertions(+), 10 deletions(-) diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c index 26b19ccad89b..6380de7cd90f 100644 --- a/fs/bcachefs/alloc_background.c +++ b/fs/bcachefs/alloc_background.c @@ -302,15 +302,6 @@ int bch2_alloc_v4_invalid(const struct bch_fs *c, struct bkey_s_c k, return 0; } -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 cc856150a948..b9955f937657 100644 --- a/fs/bcachefs/backpointers.c +++ b/fs/bcachefs/backpointers.c @@ -76,7 +76,7 @@ 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 547e0617602a..b0006e656f3a 100644 --- 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(const 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 *); -- 2.41.0
