mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-10-01 14:44:12 +00:00
Code Issues Releases Wiki Activity

bcachefs: trans_for_each_path_safe()

Browse source 
bch2_btree_trans_to_text() is used on btree_trans objects that are owned
by different threads - when printing out deadlock cycles - so we need a
safe version of trans_for_each_path(), else we race with seeing a
btree_path that was just allocated and not fully initialized:

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-05-27 19:55:54 -04:00
parent e7ffda565a
commit f154c3eb42
3 changed files with 39 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
fs/bcachefs/btree_iter.c
View file

@ -2914,6 +2914,10 @@ static void bch2_trans_alloc_paths(struct btree_trans *trans, struct bch_fs *c)
#endif
if (!p)
p = mempool_alloc(&trans->c->btree_paths_pool, GFP_NOFS);
/*
* paths need to be zeroed, bch2_check_for_deadlock looks at paths in
* other threads
*/
trans->paths = p; p += paths_bytes;
trans->updates = p; p += updates_bytes;
@ -3111,7 +3115,7 @@ void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
struct btree_path *path;
struct btree_bkey_cached_common *b;
static char lock_types[] = { 'r', 'i', 'w' };
unsigned l;
unsigned l, idx;
if (!out->nr_tabstops) {
printbuf_tabstop_push(out, 16);
@ -3120,7 +3124,7 @@ void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
prt_printf(out, "%i %s\n", trans->locking_wait.task->pid, trans->fn);
trans_for_each_path(trans, path) {
trans_for_each_path_safe(trans, path, idx) {
if (!path->nodes_locked)
continue;

29
fs/bcachefs/btree_iter.h
View file

@ -89,6 +89,35 @@ __trans_next_path(struct btree_trans *trans, unsigned idx)
#define trans_for_each_path(_trans, _path) \
trans_for_each_path_from(_trans, _path, 0)
static inline struct btree_path *
__trans_next_path_safe(struct btree_trans *trans, unsigned *idx)
{
u64 l;
if (*idx == BTREE_ITER_MAX)
return NULL;
l = trans->paths_allocated >> *idx;
if (!l)
return NULL;
*idx += __ffs64(l);
EBUG_ON(*idx >= BTREE_ITER_MAX);
return &trans->paths[*idx];
}
/*
* This version is intended to be safe for use on a btree_trans that is owned by
* another thread, for bch2_btree_trans_to_text();
*/
#define trans_for_each_path_safe_from(_trans, _path, _idx, _start) \
for (_idx = _start; \
(_path = __trans_next_path_safe((_trans), &_idx)); \
_idx++)
#define trans_for_each_path_safe(_trans, _path, _idx) \
trans_for_each_path_safe_from(_trans, _path, _idx, 0)
static inline struct btree_path *next_btree_path(struct btree_trans *trans, struct btree_path *path)
{
unsigned idx = path ? path->sorted_idx + 1 : 0;

7
fs/bcachefs/btree_locking.c
View file

@ -255,6 +255,7 @@ int bch2_check_for_deadlock(struct btree_trans *trans, struct printbuf *cycle)
struct trans_waiting_for_lock *top;
struct btree_bkey_cached_common *b;
struct btree_path *path;
unsigned path_idx;
int ret;
if (trans->lock_must_abort) {
@ -273,12 +274,12 @@ int bch2_check_for_deadlock(struct btree_trans *trans, struct printbuf *cycle)
top = &g.g[g.nr - 1];
trans_for_each_path_from(top->trans, path, top->path_idx) {
trans_for_each_path_safe_from(top->trans, path, path_idx, top->path_idx) {
if (!path->nodes_locked)
continue;
if (top->path_idx != path->idx) {
top->path_idx = path->idx;
if (path_idx != top->path_idx) {
top->path_idx = path_idx;
top->level = 0;
top->lock_start_time = 0;
}