kernel_5.10 no rt

hc

2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f

 kernel/fs/btrfs/locking.h
..
..
@@ -6,24 +6,118 @@
6
6
 #ifndef BTRFS_LOCKING_H
7
7
 #define BTRFS_LOCKING_H
8
8
 
9
+#include <linux/atomic.h>
10
+#include <linux/wait.h>
11
+#include <linux/percpu_counter.h>
12
+#include "extent_io.h"
13
+
9
14
 #define BTRFS_WRITE_LOCK 1
10
15
 #define BTRFS_READ_LOCK 2
11
16
 #define BTRFS_WRITE_LOCK_BLOCKING 3
12
17
 #define BTRFS_READ_LOCK_BLOCKING 4
13
18
 
19
+/*
20
+ * We are limited in number of subclasses by MAX_LOCKDEP_SUBCLASSES, which at
21
+ * the time of this patch is 8, which is how many we use.  Keep this in mind if
22
+ * you decide you want to add another subclass.
23
+ */
24
+enum btrfs_lock_nesting {
25
+	BTRFS_NESTING_NORMAL,
26
+
27
+	/*
28
+	 * When we COW a block we are holding the lock on the original block,
29
+	 * and since our lockdep maps are rootid+level, this confuses lockdep
30
+	 * when we lock the newly allocated COW'd block.  Handle this by having
31
+	 * a subclass for COW'ed blocks so that lockdep doesn't complain.
32
+	 */
33
+	BTRFS_NESTING_COW,
34
+
35
+	/*
36
+	 * Oftentimes we need to lock adjacent nodes on the same level while
37
+	 * still holding the lock on the original node we searched to, such as
38
+	 * for searching forward or for split/balance.
39
+	 *
40
+	 * Because of this we need to indicate to lockdep that this is
41
+	 * acceptable by having a different subclass for each of these
42
+	 * operations.
43
+	 */
44
+	BTRFS_NESTING_LEFT,
45
+	BTRFS_NESTING_RIGHT,
46
+
47
+	/*
48
+	 * When splitting we will be holding a lock on the left/right node when
49
+	 * we need to cow that node, thus we need a new set of subclasses for
50
+	 * these two operations.
51
+	 */
52
+	BTRFS_NESTING_LEFT_COW,
53
+	BTRFS_NESTING_RIGHT_COW,
54
+
55
+	/*
56
+	 * When splitting we may push nodes to the left or right, but still use
57
+	 * the subsequent nodes in our path, keeping our locks on those adjacent
58
+	 * blocks.  Thus when we go to allocate a new split block we've already
59
+	 * used up all of our available subclasses, so this subclass exists to
60
+	 * handle this case where we need to allocate a new split block.
61
+	 */
62
+	BTRFS_NESTING_SPLIT,
63
+
64
+	/*
65
+	 * When promoting a new block to a root we need to have a special
66
+	 * subclass so we don't confuse lockdep, as it will appear that we are
67
+	 * locking a higher level node before a lower level one.  Copying also
68
+	 * has this problem as it appears we're locking the same block again
69
+	 * when we make a snapshot of an existing root.
70
+	 */
71
+	BTRFS_NESTING_NEW_ROOT,
72
+
73
+	/*
74
+	 * We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so
75
+	 * add this in here and add a static_assert to keep us from going over
76
+	 * the limit.  As of this writing we're limited to 8, and we're
77
+	 * definitely using 8, hence this check to keep us from messing up in
78
+	 * the future.
79
+	 */
80
+	BTRFS_NESTING_MAX,
81
+};
82
+
83
+static_assert(BTRFS_NESTING_MAX <= MAX_LOCKDEP_SUBCLASSES,
84
+	      "too many lock subclasses defined");
85
+
86
+struct btrfs_path;
87
+
88
+void __btrfs_tree_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest);
14
89
 void btrfs_tree_lock(struct extent_buffer *eb);
15
90
 void btrfs_tree_unlock(struct extent_buffer *eb);
16
91
 
92
+void __btrfs_tree_read_lock(struct extent_buffer *eb, enum btrfs_lock_nesting nest,
93
+			    bool recurse);
17
94
 void btrfs_tree_read_lock(struct extent_buffer *eb);
18
95
 void btrfs_tree_read_unlock(struct extent_buffer *eb);
19
96
 void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb);
20
-void btrfs_set_lock_blocking_rw(struct extent_buffer *eb, int rw);
21
-void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw);
22
-void btrfs_assert_tree_locked(struct extent_buffer *eb);
97
+void btrfs_set_lock_blocking_read(struct extent_buffer *eb);
98
+void btrfs_set_lock_blocking_write(struct extent_buffer *eb);
23
99
 int btrfs_try_tree_read_lock(struct extent_buffer *eb);
24
100
 int btrfs_try_tree_write_lock(struct extent_buffer *eb);
25
101
 int btrfs_tree_read_lock_atomic(struct extent_buffer *eb);
102
+struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root);
103
+struct extent_buffer *__btrfs_read_lock_root_node(struct btrfs_root *root,
104
+						  bool recurse);
26
105
 
106
+static inline struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
107
+{
108
+	return __btrfs_read_lock_root_node(root, false);
109
+}
110
+
111
+#ifdef CONFIG_BTRFS_DEBUG
112
+static inline void btrfs_assert_tree_locked(struct extent_buffer *eb) {
113
+	BUG_ON(!eb->write_locks);
114
+}
115
+#else
116
+static inline void btrfs_assert_tree_locked(struct extent_buffer *eb) { }
117
+#endif
118
+
119
+void btrfs_set_path_blocking(struct btrfs_path *p);
120
+void btrfs_unlock_up_safe(struct btrfs_path *path, int level);
27
121
 
28
122
 static inline void btrfs_tree_unlock_rw(struct extent_buffer *eb, int rw)
29
123
 {
..
..
@@ -37,13 +131,19 @@
37
131
 		BUG();
38
132
 }
39
133
 
40
-static inline void btrfs_set_lock_blocking(struct extent_buffer *eb)
41
-{
42
-	btrfs_set_lock_blocking_rw(eb, BTRFS_WRITE_LOCK);
43
-}
134
+struct btrfs_drew_lock {
135
+	atomic_t readers;
136
+	struct percpu_counter writers;
137
+	wait_queue_head_t pending_writers;
138
+	wait_queue_head_t pending_readers;
139
+};
44
140
 
45
-static inline void btrfs_clear_lock_blocking(struct extent_buffer *eb)
46
-{
47
-	btrfs_clear_lock_blocking_rw(eb, BTRFS_WRITE_LOCK_BLOCKING);
48
-}
141
+int btrfs_drew_lock_init(struct btrfs_drew_lock *lock);
142
+void btrfs_drew_lock_destroy(struct btrfs_drew_lock *lock);
143
+void btrfs_drew_write_lock(struct btrfs_drew_lock *lock);
144
+bool btrfs_drew_try_write_lock(struct btrfs_drew_lock *lock);
145
+void btrfs_drew_write_unlock(struct btrfs_drew_lock *lock);
146
+void btrfs_drew_read_lock(struct btrfs_drew_lock *lock);
147
+void btrfs_drew_read_unlock(struct btrfs_drew_lock *lock);
148
+
49
149
 #endif