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bcachefs: Cached pointers should not be erasure coded

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There's no reason to erasure code cached pointers: we'll always have
another copy, and it'll be cheaper to read the other copy than do a
reconstruct read. And erasure coded cached pointers would add
complications that we'd rather not have to deal with, so let's make sure
to disallow them.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-02-21 19:22:44 -05:00
parent e094beccc1
commit c9163bb03b
3 changed files with 37 additions and 3 deletions
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6
fs/bcachefs/data_update.c
View file

@ -97,8 +97,10 @@ static void bch2_bkey_mark_dev_cached(struct bkey_s k, unsigned dev)
struct bch_extent_ptr *ptr;
bkey_for_each_ptr(ptrs, ptr)
if (ptr->dev == dev)
ptr->cached = true;
if (ptr->dev == dev) {
bch2_extent_ptr_set_cached(k, ptr);
return;
}
}
static int __bch2_data_update_index_update(struct btree_trans *trans,

32
fs/bcachefs/extents.c
View file

@ -950,6 +950,29 @@ bool bch2_extent_has_ptr(struct bkey_s_c k1, struct extent_ptr_decoded p1,
return false;
}
void bch2_extent_ptr_set_cached(struct bkey_s k, struct bch_extent_ptr *ptr)
{
struct bkey_ptrs ptrs = bch2_bkey_ptrs(k);
union bch_extent_entry *entry;
union bch_extent_entry *ec = NULL;
bkey_extent_entry_for_each(ptrs, entry) {
if (&entry->ptr == ptr) {
ptr->cached = true;
if (ec)
extent_entry_drop(k, ec);
return;
}
if (extent_entry_is_stripe_ptr(entry))
ec = entry;
else if (extent_entry_is_ptr(entry))
ec = NULL;
}
BUG();
}
/*
* bch_extent_normalize - clean up an extent, dropping stale pointers etc.
*
@ -1093,7 +1116,7 @@ int bch2_bkey_ptrs_invalid(const struct bch_fs *c, struct bkey_s_c k,
unsigned size_ondisk = k.k->size;
unsigned nonce = UINT_MAX;
unsigned nr_ptrs = 0;
bool unwritten = false;
bool unwritten = false, have_ec = false;
int ret;
if (bkey_is_btree_ptr(k.k))
@ -1129,7 +1152,13 @@ int bch2_bkey_ptrs_invalid(const struct bch_fs *c, struct bkey_s_c k,
return -BCH_ERR_invalid_bkey;
}
if (entry->ptr.cached && have_ec) {
prt_printf(err, "cached, erasure coded ptr");
return -BCH_ERR_invalid_bkey;
}
unwritten = entry->ptr.unwritten;
have_ec = false;
nr_ptrs++;
break;
case BCH_EXTENT_ENTRY_crc32:
@ -1165,6 +1194,7 @@ int bch2_bkey_ptrs_invalid(const struct bch_fs *c, struct bkey_s_c k,
}
break;
case BCH_EXTENT_ENTRY_stripe_ptr:
have_ec = true;
break;
}
}

2
fs/bcachefs/extents.h
View file

@ -655,6 +655,8 @@ bool bch2_bkey_matches_ptr(struct bch_fs *, struct bkey_s_c,
bool bch2_extents_match(struct bkey_s_c, struct bkey_s_c);
bool bch2_extent_has_ptr(struct bkey_s_c, struct extent_ptr_decoded, struct bkey_s_c);
void bch2_extent_ptr_set_cached(struct bkey_s, struct bch_extent_ptr *);
bool bch2_extent_normalize(struct bch_fs *, struct bkey_s);
void bch2_bkey_ptrs_to_text(struct printbuf *, struct bch_fs *,
struct bkey_s_c);