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bcachefs: Kill nodes_intent_locked

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Previously, we used two different bit arrays for tracking held btree
node locks. This patch switches to an array of two bit integers, which
will let us track, in a future patch, when we hold a write lock.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2022-08-21 17:20:42 -04:00 committed by Kent Overstreet
parent d4263e5638
commit 2e27f6567b
3 changed files with 9 additions and 24 deletions
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2
fs/bcachefs/btree_iter.c
View File

@ -1519,7 +1519,6 @@ static struct btree_path *btree_path_alloc(struct btree_trans *trans,
path->ref = 0; path->ref = 0;
path->intent_ref = 0; path->intent_ref = 0;
path->nodes_locked = 0; path->nodes_locked = 0;
path->nodes_intent_locked = 0;
btree_path_list_add(trans, pos, path); btree_path_list_add(trans, pos, path);
trans->paths_sorted = false; trans->paths_sorted = false;
@ -1574,7 +1573,6 @@ struct btree_path *bch2_path_get(struct btree_trans *trans,
path->level = level; path->level = level;
path->locks_want = locks_want; path->locks_want = locks_want;
path->nodes_locked = 0; path->nodes_locked = 0;
path->nodes_intent_locked = 0;
for (i = 0; i < ARRAY_SIZE(path->l); i++) for (i = 0; i < ARRAY_SIZE(path->l); i++)
path->l[i].b = ERR_PTR(-BCH_ERR_no_btree_node_init); path->l[i].b = ERR_PTR(-BCH_ERR_no_btree_node_init);
#ifdef CONFIG_BCACHEFS_DEBUG #ifdef CONFIG_BCACHEFS_DEBUG

26
fs/bcachefs/btree_locking.h
View File

@ -37,14 +37,7 @@ enum btree_node_locked_type {
static inline int btree_node_locked_type(struct btree_path *path, static inline int btree_node_locked_type(struct btree_path *path,
unsigned level) unsigned level)
{ {
/* return BTREE_NODE_UNLOCKED + ((path->nodes_locked >> (level << 1)) & 3);
* We're relying on the fact that if nodes_intent_locked is set
* nodes_locked must be set as well, so that we can compute without
* branches:
*/
return BTREE_NODE_UNLOCKED +
((path->nodes_locked >> level) & 1) +
((path->nodes_intent_locked >> level) & 1);
} }
static inline bool btree_node_intent_locked(struct btree_path *path, static inline bool btree_node_intent_locked(struct btree_path *path,
@ -65,20 +58,15 @@ static inline bool btree_node_locked(struct btree_path *path, unsigned level)
} }
static inline void mark_btree_node_locked_noreset(struct btree_path *path, static inline void mark_btree_node_locked_noreset(struct btree_path *path,
unsigned level, unsigned level,
enum btree_node_locked_type type) enum btree_node_locked_type type)
{ {
/* relying on this to avoid a branch */ /* relying on this to avoid a branch */
BUILD_BUG_ON(SIX_LOCK_read != 0); BUILD_BUG_ON(SIX_LOCK_read != 0);
BUILD_BUG_ON(SIX_LOCK_intent != 1); BUILD_BUG_ON(SIX_LOCK_intent != 1);
path->nodes_locked &= ~(1 << level); path->nodes_locked &= ~(3U << (level << 1));
path->nodes_intent_locked &= ~(1 << level); path->nodes_locked |= (type + 1) << (level << 1);
if (type != BTREE_NODE_UNLOCKED) {
path->nodes_locked |= 1 << level;
path->nodes_intent_locked |= type << level;
}
} }
static inline void mark_btree_node_unlocked(struct btree_path *path, static inline void mark_btree_node_unlocked(struct btree_path *path,
@ -162,12 +150,12 @@ static inline void btree_node_unlock(struct btree_trans *trans,
static inline int btree_path_lowest_level_locked(struct btree_path *path) static inline int btree_path_lowest_level_locked(struct btree_path *path)
{ {
return __ffs(path->nodes_locked); return __ffs(path->nodes_locked) >> 1;
} }
static inline int btree_path_highest_level_locked(struct btree_path *path) static inline int btree_path_highest_level_locked(struct btree_path *path)
{ {
return __fls(path->nodes_locked); return __fls(path->nodes_locked) >> 1;
} }
static inline void __bch2_btree_path_unlock(struct btree_trans *trans, static inline void __bch2_btree_path_unlock(struct btree_trans *trans,

5
fs/bcachefs/btree_types.h
View File

@ -232,9 +232,8 @@ struct btree_path {
*/ */
bool should_be_locked:1; bool should_be_locked:1;
unsigned level:3, unsigned level:3,
locks_want:4, locks_want:4;
nodes_locked:4, u8 nodes_locked;
nodes_intent_locked:4;
struct btree_path_level { struct btree_path_level {
struct btree *b; struct btree *b;