Commit ca43f73c authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: bch2_btree_write_buffer_flush_going_ro() 



The write buffer needs to be specifically flushed when going RO: keys in
the journal that haven't yet been moved to the write buffer don't have a
journal pin yet.

This fixes numerous syzbot bugs, all with symptoms of still doing writes
after we've got RO.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 8440da93

fs/bcachefs/btree_write_buffer.c

+27 −3
Original line number Diff line number Diff line
@@ -277,6 +277,10 @@ static int bch2_btree_write_buffer_flush_locked(struct btree_trans *trans) 
	bool accounting_replay_done = test_bit(BCH_FS_accounting_replay_done, &c->flags);

	int ret = 0;



	ret = bch2_journal_error(&c->journal);

	if (ret)

		return ret;



	bch2_trans_unlock(trans);

	bch2_trans_begin(trans);
@@ -491,7 +495,8 @@ static int fetch_wb_keys_from_journal(struct bch_fs *c, u64 seq) 
	return ret;

}



static int btree_write_buffer_flush_seq(struct btree_trans *trans, u64 seq)

static int btree_write_buffer_flush_seq(struct btree_trans *trans, u64 seq,

					bool *did_work)

{

	struct bch_fs *c = trans->c;

	struct btree_write_buffer *wb = &c->btree_write_buffer;
@@ -502,6 +507,8 @@ static int btree_write_buffer_flush_seq(struct btree_trans *trans, u64 seq) 


		fetch_from_journal_err = fetch_wb_keys_from_journal(c, seq);



		*did_work |= wb->inc.keys.nr || wb->flushing.keys.nr;



		/*

		 * On memory allocation failure, bch2_btree_write_buffer_flush_locked()

		 * is not guaranteed to empty wb->inc:
@@ -521,17 +528,34 @@ static int bch2_btree_write_buffer_journal_flush(struct journal *j, 
				struct journal_entry_pin *_pin, u64 seq)

{

	struct bch_fs *c = container_of(j, struct bch_fs, journal);

	bool did_work = false;



	return bch2_trans_run(c, btree_write_buffer_flush_seq(trans, seq));

	return bch2_trans_run(c, btree_write_buffer_flush_seq(trans, seq, &did_work));

}



int bch2_btree_write_buffer_flush_sync(struct btree_trans *trans)

{

	struct bch_fs *c = trans->c;

	bool did_work = false;



	trace_and_count(c, write_buffer_flush_sync, trans, _RET_IP_);



	return btree_write_buffer_flush_seq(trans, journal_cur_seq(&c->journal));

	return btree_write_buffer_flush_seq(trans, journal_cur_seq(&c->journal), &did_work);

}



/*

 * The write buffer requires flushing when going RO: keys in the journal for the

 * write buffer don't have a journal pin yet

 */

bool bch2_btree_write_buffer_flush_going_ro(struct bch_fs *c)

{

	if (bch2_journal_error(&c->journal))

		return false;



	bool did_work = false;

	bch2_trans_run(c, btree_write_buffer_flush_seq(trans,

				journal_cur_seq(&c->journal), &did_work));

	return did_work;

}



int bch2_btree_write_buffer_flush_nocheck_rw(struct btree_trans *trans)

fs/bcachefs/btree_write_buffer.h

+1 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ static inline bool bch2_btree_write_buffer_must_wait(struct bch_fs *c) 


struct btree_trans;

int bch2_btree_write_buffer_flush_sync(struct btree_trans *);

bool bch2_btree_write_buffer_flush_going_ro(struct bch_fs *);

int bch2_btree_write_buffer_flush_nocheck_rw(struct btree_trans *);

int bch2_btree_write_buffer_tryflush(struct btree_trans *);

fs/bcachefs/super.c

+1 −0
Original line number Diff line number Diff line
@@ -272,6 +272,7 @@ static void __bch2_fs_read_only(struct bch_fs *c) 
		clean_passes++;



		if (bch2_btree_interior_updates_flush(c) ||

		    bch2_btree_write_buffer_flush_going_ro(c) ||

		    bch2_journal_flush_all_pins(&c->journal) ||

		    bch2_btree_flush_all_writes(c) ||

		    seq != atomic64_read(&c->journal.seq)) {