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bcachefs: use swab40 for bch_backpointer.bucket_offset bitfield

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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>
This commit is contained in:
Brian Foster 2023-11-03 09:09:38 -04:00 committed by Kent Overstreet
parent 0996c72a0f
commit 7cb2a7895d
3 changed files with 10 additions and 10 deletions
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9
fs/bcachefs/alloc_background.c
View File

@ -297,15 +297,6 @@ int bch2_alloc_v4_invalid(struct bch_fs *c, struct bkey_s_c k,
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;

2
fs/bcachefs/backpointers.c
View File

@ -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);
}

9
fs/bcachefs/backpointers.h
View File

@ -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 *);