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bcachefs: Add a counter for btree_trans restarts

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This will help us improve nested transactions - we need to add
assertions that whenever an inner transaction handles a restart, it
still returns -EINTR to the outer transaction.

This also adds nested_lockrestart_do() and nested_commit_do() which use
the new counters to correctly return -EINTR when the transaction was
restarted.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2022-07-17 19:35:38 -04:00 committed by Kent Overstreet
parent 445d184af2
commit e941ae7d3a
4 changed files with 63 additions and 15 deletions
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13
fs/bcachefs/btree_iter.c
View File

@ -3188,7 +3188,7 @@ void *bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
* node may return EINTR when the trylock fails. When this occurs
* bch2_trans_begin() should be called and the transaction retried.
*/
void bch2_trans_begin(struct btree_trans *trans)
u32 bch2_trans_begin(struct btree_trans *trans)
{
struct btree_path *path;
@ -3234,11 +3234,20 @@ void bch2_trans_begin(struct btree_trans *trans)
bch2_trans_relock(trans);
}
trans->last_restarted_ip = _RET_IP_;
if (trans->restarted)
bch2_btree_path_traverse_all(trans);
trans->restarted = false;
trans->last_begin_time = ktime_get_ns();
return trans->restart_count;
}
void bch2_trans_verify_not_restarted(struct btree_trans *trans, u32 restart_count)
{
bch2_trans_inconsistent_on(trans_was_restarted(trans, restart_count), trans,
"trans->restart_count %u, should be %u, last restarted by %ps\n",
trans->restart_count, restart_count,
(void *) trans->last_restarted_ip);
}
static void bch2_trans_alloc_paths(struct btree_trans *trans, struct bch_fs *c)

46
fs/bcachefs/btree_iter.h
View File

@ -203,10 +203,18 @@ void bch2_path_put(struct btree_trans *, struct btree_path *, bool);
bool bch2_trans_relock(struct btree_trans *);
void bch2_trans_unlock(struct btree_trans *);
static inline int trans_was_restarted(struct btree_trans *trans, u32 restart_count)
{
return restart_count != trans->restart_count ? -EINTR : 0;
}
void bch2_trans_verify_not_restarted(struct btree_trans *, u32);
__always_inline
static inline int btree_trans_restart(struct btree_trans *trans)
{
trans->restarted = true;
trans->restart_count++;
bch2_trans_unlock(trans);
return -EINTR;
}
@ -321,7 +329,7 @@ static inline void set_btree_iter_dontneed(struct btree_iter *iter)
}
void *bch2_trans_kmalloc(struct btree_trans *, size_t);
void bch2_trans_begin(struct btree_trans *);
u32 bch2_trans_begin(struct btree_trans *);
static inline struct btree *
__btree_iter_peek_node_and_restart(struct btree_trans *trans, struct btree_iter *iter)
@ -394,6 +402,42 @@ __bch2_btree_iter_peek_and_restart(struct btree_trans *trans,
return k;
}
#define lockrestart_do(_trans, _do) \
({ \
int _ret; \
\
do { \
bch2_trans_begin(_trans); \
_ret = (_do); \
} while (_ret == -EINTR); \
\
_ret; \
})
/*
* nested_lockrestart_do(), nested_commit_do():
*
* These are like lockrestart_do() and commit_do(), with two differences:
*
* - We don't call bch2_trans_begin() unless we had a transaction restart
* - We return -EINTR if we succeeded after a transaction restart
*/
#define nested_lockrestart_do(_trans, _do) \
({ \
u32 _restart_count, _orig_restart_count; \
int _ret; \
\
_restart_count = _orig_restart_count = (_trans)->restart_count; \
\
while ((_ret = (_do)) == -EINTR) \
_restart_count = bch2_trans_begin(_trans); \
\
if (!_ret) \
bch2_trans_verify_not_restarted(_trans, _restart_count);\
\
_ret ?: trans_was_restarted(_trans, _orig_restart_count); \
})
#define for_each_btree_key2(_trans, _iter, _btree_id, \
_start, _flags, _k, _do) \
({ \

3
fs/bcachefs/btree_types.h
View File

@ -410,6 +410,9 @@ struct btree_trans {
bool memory_allocation_failure:1;
bool journal_transaction_names:1;
bool journal_replay_not_finished:1;
u32 restart_count;
unsigned long last_restarted_ip;
/*
* For when bch2_trans_update notices we'll be splitting a compressed
* extent:

16
fs/bcachefs/btree_update.h
View File

@ -106,22 +106,14 @@ static inline int bch2_trans_commit(struct btree_trans *trans,
return __bch2_trans_commit(trans);
}
#define lockrestart_do(_trans, _do) \
({ \
int _ret; \
\
do { \
bch2_trans_begin(_trans); \
_ret = (_do); \
} while (_ret == -EINTR); \
\
_ret; \
})
#define commit_do(_trans, _disk_res, _journal_seq, _flags, _do) \
lockrestart_do(_trans, _do ?: bch2_trans_commit(_trans, (_disk_res),\
(_journal_seq), (_flags)))
#define nested_commit_do(_trans, _disk_res, _journal_seq, _flags, _do) \
nested_lockrestart_do(_trans, _do ?: bch2_trans_commit(_trans, (_disk_res),\
(_journal_seq), (_flags)))
#define bch2_trans_do(_c, _disk_res, _journal_seq, _flags, _do) \
({ \
struct btree_trans trans; \