diff options
Diffstat (limited to 'fs/bcachefs/bcachefs_format.h')
| -rw-r--r-- | fs/bcachefs/bcachefs_format.h | 37 |
1 files changed, 35 insertions, 2 deletions
diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h index 1bb24aa73528..bff8750ac0d7 100644 --- a/fs/bcachefs/bcachefs_format.h +++ b/fs/bcachefs/bcachefs_format.h @@ -189,7 +189,11 @@ struct bversion { __u32 hi; __u64 lo; #endif -} __packed __aligned(4); +} __packed +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ +__aligned(4) +#endif +; struct bkey { /* Size of combined key and value, in u64s */ @@ -222,7 +226,36 @@ struct bkey { __u8 pad[1]; #endif -} __packed __aligned(8); +} __packed +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ +/* + * The big-endian version of bkey can't be compiled by rustc with the "aligned" + * attr since it doesn't allow types to have both "packed" and "aligned" attrs. + * So for Rust compatibility, don't include this. It can be included in the LE + * version because the "packed" attr is redundant in that case. + * + * History: (quoting Kent) + * + * Specifically, when i was designing bkey, I wanted the header to be no + * bigger than necessary so that bkey_packed could use the rest. That means that + * decently offten extent keys will fit into only 8 bytes, instead of spilling over + * to 16. + * + * But packed_bkey treats the part after the header - the packed section - + * as a single multi word, variable length integer. And bkey, the unpacked + * version, is just a special case version of a bkey_packed; all the packed + * bkey code will work on keys in any packed format, the in-memory + * representation of an unpacked key also is just one type of packed key... + * + * So that constrains the key part of a bkig endian bkey to start right + * after the header. + * + * If we ever do a bkey_v2 and need to expand the hedaer by another byte for + * some reason - that will clean up this wart. + */ +__aligned(8) +#endif +; struct bkey_packed { __u64 _data[0]; |