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bcachefs: Don't modify existing key in place in sort_repack_merge()

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This fixes a nasty memory corruption with other threads that are still
reading the btree node being compacted.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2020-01-16 16:14:56 -05:00 committed by Kent Overstreet
parent a965ef4986
commit 952070908f
1 changed files with 15 additions and 5 deletions
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20
fs/bcachefs/bkey_sort.c
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@ -210,28 +210,38 @@ bch2_sort_repack_merge(struct bch_fs *c,
bool filter_whiteouts)
{
struct bkey_packed *prev = NULL, *k_packed;
struct bkey_s k;
struct bkey_on_stack k;
struct btree_nr_keys nr;
struct bkey unpacked;
memset(&nr, 0, sizeof(nr));
bkey_on_stack_init(&k);
while ((k_packed = bch2_btree_node_iter_next_all(iter, src))) {
if (filter_whiteouts && bkey_whiteout(k_packed))
continue;
k = __bkey_disassemble(src, k_packed, &unpacked);
/*
* NOTE:
* bch2_bkey_normalize may modify the key we pass it (dropping
* stale pointers) and we don't have a write lock on the src
* node; we have to make a copy of the entire key before calling
* normalize
*/
bkey_on_stack_realloc(&k, c, k_packed->u64s + BKEY_U64s);
bch2_bkey_unpack(src, k.k, k_packed);
if (filter_whiteouts &&
bch2_bkey_normalize(c, k))
bch2_bkey_normalize(c, bkey_i_to_s(k.k)))
continue;
extent_sort_append(c, out_f, &nr, vstruct_last(dst), &prev, k);
extent_sort_append(c, out_f, &nr, vstruct_last(dst),
&prev, bkey_i_to_s(k.k));
}
extent_sort_advance_prev(out_f, &nr, vstruct_last(dst), &prev);
dst->u64s = cpu_to_le16((u64 *) prev - dst->_data);
bkey_on_stack_exit(&k, c);
return nr;
}