Commit dfd41fb9 authored by Kent Overstreet's avatar Kent Overstreet Committed by Kent Overstreet
Browse files

bcachefs: Fix race between btree updates & journal replay 



Add a flag to indicate whether a journal replay key has been
overwritten, and set/test it with appropriate btree locks held.

This fixes a race between the allocator - invalidating buckets, and
doing btree updates - and journal replay, which before this patch could
clobber the allocator thread's update with an older version of the key
from the journal.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@gmail.com>
parent 528b18e6

fs/bcachefs/bcachefs.h

+1 −0
Original line number Diff line number Diff line
@@ -561,6 +561,7 @@ struct journal_keys { 
		enum btree_id	btree_id:8;

		unsigned	level:8;

		bool		allocated;

		bool		overwritten;

		struct bkey_i	*k;

		u32		journal_seq;

		u32		journal_offset;

fs/bcachefs/btree_update_leaf.c

+12 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include "journal.h"

#include "journal_reclaim.h"

#include "keylist.h"

#include "recovery.h"

#include "subvolume.h"

#include "replicas.h"

#include "trace.h"
@@ -625,6 +626,14 @@ static inline int trans_lock_write(struct btree_trans *trans) 
	return btree_trans_restart(trans);

}



static noinline void bch2_drop_overwrites_from_journal(struct btree_trans *trans)

{

	struct btree_insert_entry *i;



	trans_for_each_update(trans, i)

		bch2_journal_key_overwritten(trans->c, i->btree_id, i->level, i->k->k.p);

}



/*

 * Get journal reservation, take write locks, and attempt to do btree update(s):

 */
@@ -702,6 +711,9 @@ static inline int do_bch2_trans_commit(struct btree_trans *trans, 


	ret = bch2_trans_commit_write_locked(trans, stopped_at, trace_ip);



	if (!ret && unlikely(!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags)))

		bch2_drop_overwrites_from_journal(trans);



	trans_for_each_update(trans, i)

		if (!same_leaf_as_prev(trans, i))

			bch2_btree_node_unlock_write_inlined(trans, i->path,

fs/bcachefs/recovery.c

+23 −2
Original line number Diff line number Diff line
@@ -185,6 +185,19 @@ int bch2_journal_key_delete(struct bch_fs *c, enum btree_id id, 
	return bch2_journal_key_insert(c, id, level, &whiteout);

}



void bch2_journal_key_overwritten(struct bch_fs *c, enum btree_id btree,

				  unsigned level, struct bpos pos)

{

	struct journal_keys *keys = &c->journal_keys;

	size_t idx = journal_key_search(keys, btree, level, pos);



	if (idx < keys->nr &&

	    keys->d[idx].btree_id	== btree &&

	    keys->d[idx].level		== level &&

	    !bpos_cmp(keys->d[idx].k->k.p, pos))

		keys->d[idx].overwritten = true;

}



static struct bkey_i *bch2_journal_iter_peek(struct journal_iter *iter)

{

	struct journal_key *k = iter->idx - iter->keys->nr
@@ -539,8 +552,16 @@ static int __bch2_journal_replay_key(struct btree_trans *trans, 
	bch2_trans_node_iter_init(trans, &iter, k->btree_id, k->k->k.p,

				  BTREE_MAX_DEPTH, k->level,

				  iter_flags);

	ret   = bch2_btree_iter_traverse(&iter) ?:

		bch2_trans_update(trans, &iter, k->k, BTREE_TRIGGER_NORUN);

	ret = bch2_btree_iter_traverse(&iter);

	if (ret)

		goto out;



	/* Must be checked with btree locked: */

	if (k->overwritten)

		goto out;



	ret = bch2_trans_update(trans, &iter, k->k, BTREE_TRIGGER_NORUN);

out:

	bch2_trans_iter_exit(trans, &iter);

	return ret;

}

fs/bcachefs/recovery.h

+2 −0
Original line number Diff line number Diff line
@@ -37,6 +37,8 @@ int bch2_journal_key_insert(struct bch_fs *, enum btree_id, 
			    unsigned, struct bkey_i *);

int bch2_journal_key_delete(struct bch_fs *, enum btree_id,

			    unsigned, struct bpos);

void bch2_journal_key_overwritten(struct bch_fs *, enum btree_id,

				  unsigned, struct bpos);



void bch2_btree_and_journal_iter_advance(struct btree_and_journal_iter *);

struct bkey_s_c bch2_btree_and_journal_iter_peek(struct btree_and_journal_iter *);