From: Josef Bacik <josef@toxicpanda.com>
To: linux-btrfs@vger.kernel.org, kernel-team@fb.com
Subject: [PATCH 05/12] btrfs: introduce BTRFS_NESTING_LEFT/BTRFS_NESTING_RIGHT
Date: Thu, 20 Aug 2020 11:46:04 -0400 [thread overview]
Message-ID: <07d7ef8f401ec5b0b24ae58b4da7f0f49c9651fc.1597938191.git.josef@toxicpanda.com> (raw)
In-Reply-To: <cover.1597938190.git.josef@toxicpanda.com>
Our lockdep maps are based on rootid+level, however in some cases we
will lock adjacent blocks on the same level, namely in searching forward
or in split/balance. Because of this lockdep will complain, so we need
a separate subclass to indicate to lockdep that these are different
locks.
lock leaf -> BTRFS_NESTING_NORMAL
cow leaf -> BTRFS_NESTING_COW
split leaf
lock left -> BTRFS_NESTING_LEFT
lock right -> BTRFS_NESTING_RIGHT
The above graph illustrates the need for this new nesting subclass.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/ctree.c | 16 ++++++++--------
fs/btrfs/locking.h | 12 ++++++++++++
2 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index d8f0e128c7ba..a4b2439a398a 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1896,7 +1896,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
left = NULL;
if (left) {
- btrfs_tree_lock(left);
+ __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
btrfs_set_lock_blocking_write(left);
wret = btrfs_cow_block(trans, root, left,
parent, pslot - 1, &left,
@@ -1912,7 +1912,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
right = NULL;
if (right) {
- btrfs_tree_lock(right);
+ __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
btrfs_set_lock_blocking_write(right);
wret = btrfs_cow_block(trans, root, right,
parent, pslot + 1, &right,
@@ -2076,7 +2076,7 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
if (left) {
u32 left_nr;
- btrfs_tree_lock(left);
+ __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
btrfs_set_lock_blocking_write(left);
left_nr = btrfs_header_nritems(left);
@@ -2131,7 +2131,7 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
if (right) {
u32 right_nr;
- btrfs_tree_lock(right);
+ __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
btrfs_set_lock_blocking_write(right);
right_nr = btrfs_header_nritems(right);
@@ -3742,7 +3742,7 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
if (IS_ERR(right))
return 1;
- btrfs_tree_lock(right);
+ __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
btrfs_set_lock_blocking_write(right);
free_space = btrfs_leaf_free_space(right);
@@ -3975,7 +3975,7 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
if (IS_ERR(left))
return 1;
- btrfs_tree_lock(left);
+ __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
btrfs_set_lock_blocking_write(left);
free_space = btrfs_leaf_free_space(left);
@@ -5393,7 +5393,7 @@ int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
if (!ret) {
btrfs_set_path_blocking(path);
__btrfs_tree_read_lock(next,
- BTRFS_NESTING_NORMAL,
+ BTRFS_NESTING_RIGHT,
path->recurse);
}
next_rw_lock = BTRFS_READ_LOCK;
@@ -5430,7 +5430,7 @@ int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
if (!ret) {
btrfs_set_path_blocking(path);
__btrfs_tree_read_lock(next,
- BTRFS_NESTING_NORMAL,
+ BTRFS_NESTING_RIGHT,
path->recurse);
}
next_rw_lock = BTRFS_READ_LOCK;
diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h
index 5a4fdef197f5..3169c2bb6db9 100644
--- a/fs/btrfs/locking.h
+++ b/fs/btrfs/locking.h
@@ -27,6 +27,18 @@ enum btrfs_lock_nesting {
*/
BTRFS_NESTING_COW,
+ /*
+ * Oftentimes we need to lock adjacent nodes on the same level while
+ * still holding the lock on the original node we searched to, such as
+ * for searching forward or for split/balance.
+ *
+ * Because of this we need to indicate to lockdep that this is
+ * acceptable by having a different subclass for each of these
+ * operations.
+ */
+ BTRFS_NESTING_LEFT,
+ BTRFS_NESTING_RIGHT,
+
/*
* We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so
* add this in here and add a static_assert to keep us from going over
--
2.24.1
next prev parent reply other threads:[~2020-08-20 15:46 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 15:45 [PATCH 00/12] Convert btree locking to an rwsem Josef Bacik
2020-08-20 15:46 ` [PATCH 01/12] btrfs: rename eb->lock_nested to eb->lock_recursed Josef Bacik
2020-08-20 15:46 ` [PATCH 02/12] btrfs: introduce path->recurse Josef Bacik
2020-08-20 15:46 ` [PATCH 03/12] btrfs: add nesting tags to the locking helpers Josef Bacik
2020-08-20 15:46 ` [PATCH 04/12] btrfs: introduce BTRFS_NESTING_COW for cow'ing blocks Josef Bacik
2020-08-20 15:46 ` Josef Bacik [this message]
2020-08-20 15:46 ` [PATCH 06/12] btrfs: introduce BTRFS_NESTING_LEFT/RIGHT_COW Josef Bacik
2020-08-20 15:46 ` [PATCH 07/12] btrfs: introduce BTRFS_NESTING_SPLIT for split blocks Josef Bacik
2020-08-20 15:46 ` [PATCH 08/12] btrfs: introduce BTRFS_NESTING_NEW_ROOT for adding new roots Josef Bacik
2020-08-20 15:46 ` [PATCH 09/12] btrfs: use BTRFS_NESTED_NEW_ROOT for double splits Josef Bacik
2020-08-20 15:46 ` [PATCH 10/12] btrfs: change our extent buffer lock to a rw_semaphore Josef Bacik
2020-08-20 15:46 ` [PATCH 11/12] btrfs: remove all of the blocking helpers Josef Bacik
2020-08-20 15:46 ` [PATCH 12/12] btrfs: rip out path->leave_spinning Josef Bacik
2020-08-26 14:58 ` [PATCH 00/12] Convert btree locking to an rwsem David Sterba
2020-08-31 22:41 ` David Sterba
2020-11-03 20:59 ` David Sterba
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