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bcachefs: Kill bch2_verify_bucket_evacuated()

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With backpointers, it's now impossible for bch2_evacuate_bucket() to be
completely reliable: it can race with an extent being partially
overwritten or split, which needs a new write buffer flush for the
backpointer to be seen.

This shouldn't be a real issue in practice; the previous patch added a
new tracepoint so we'll be able to see more easily if it is.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-04-21 03:42:41 -04:00
parent 5a21764db1
commit 1af5227c1d
3 changed files with 0 additions and 88 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
fs/bcachefs/move.c
View File

@ -654,85 +654,6 @@ int bch2_move_data(struct bch_fs *c,
return ret;
}
void bch2_verify_bucket_evacuated(struct btree_trans *trans, struct bpos bucket, int gen)
{
struct bch_fs *c = trans->c;
struct btree_iter iter;
struct bkey_s_c k;
struct printbuf buf = PRINTBUF;
struct bch_backpointer bp;
struct bpos bp_pos = POS_MIN;
unsigned nr_bps = 0;
int ret;
bch2_trans_begin(trans);
bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
bucket, BTREE_ITER_CACHED);
again:
ret = lockrestart_do(trans,
bkey_err(k = bch2_btree_iter_peek_slot(&iter)));
if (!ret && k.k->type == KEY_TYPE_alloc_v4) {
struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(k);
if (a.v->gen == gen &&
a.v->dirty_sectors) {
if (a.v->data_type == BCH_DATA_btree) {
bch2_trans_unlock(trans);
if (bch2_btree_interior_updates_flush(c))
goto again;
goto failed_to_evacuate;
}
}
}
set_btree_iter_dontneed(&iter);
bch2_trans_iter_exit(trans, &iter);
return;
failed_to_evacuate:
bch2_trans_iter_exit(trans, &iter);
if (test_bit(BCH_FS_EMERGENCY_RO, &c->flags))
return;
prt_printf(&buf, bch2_log_msg(c, "failed to evacuate bucket "));
bch2_bkey_val_to_text(&buf, c, k);
while (1) {
bch2_trans_begin(trans);
ret = bch2_get_next_backpointer(trans, bucket, gen,
&bp_pos, &bp,
BTREE_ITER_CACHED);
if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
continue;
if (ret)
break;
if (bkey_eq(bp_pos, POS_MAX))
break;
k = bch2_backpointer_get_key(trans, &iter, bp_pos, bp, 0);
ret = bkey_err(k);
if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
continue;
if (ret)
break;
if (!k.k)
continue;
prt_newline(&buf);
bch2_bkey_val_to_text(&buf, c, k);
bch2_trans_iter_exit(trans, &iter);
if (++nr_bps > 10)
break;
bp_pos = bpos_nosnap_successor(bp_pos);
}
bch2_print_string_as_lines(KERN_ERR, buf.buf);
printbuf_exit(&buf);
}
int __bch2_evacuate_bucket(struct btree_trans *trans,
struct moving_context *ctxt,
struct move_bucket_in_flight *bucket_in_flight,

2
fs/bcachefs/move.h
View File

@ -36,8 +36,6 @@ struct moving_context {
wait_queue_head_t wait;
};
void bch2_verify_bucket_evacuated(struct btree_trans *, struct bpos, int);
#define move_ctxt_wait_event(_ctxt, _trans, _cond) \
do { \
bool cond_finished = false; \

7
fs/bcachefs/movinggc.c
View File

@ -134,13 +134,6 @@ static void move_buckets_wait(struct btree_trans *trans,
if (atomic_read(&i->count))
break;
/*
* moving_ctxt_exit calls bch2_write as it flushes pending
* reads, which inits another btree_trans; this one must be
* unlocked:
*/
bch2_verify_bucket_evacuated(trans, i->bucket.k.bucket, i->bucket.k.gen);
list->first = i->next;
if (!list->first)
list->last = NULL;