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[174.109.172.136]) by smtp.gmail.com with ESMTPSA id k134sm14842062qke.60.2020.08.10.08.43.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Aug 2020 08:43:06 -0700 (PDT) From: Josef Bacik To: linux-btrfs@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 11/17] btrfs: introduce BTRFS_NESTING_LEFT/BTRFS_NESTING_RIGHT Date: Mon, 10 Aug 2020 11:42:36 -0400 Message-Id: <20200810154242.782802-12-josef@toxicpanda.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200810154242.782802-1-josef@toxicpanda.com> References: <20200810154242.782802-1-josef@toxicpanda.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org 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 --- 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 a9699232d5bc..ea5412cd0f62 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 9e0975aa82b3..f93e3e10ddbd 100644 --- a/fs/btrfs/locking.h +++ b/fs/btrfs/locking.h @@ -26,6 +26,18 @@ enum btrfs_lock_nesting { * a subclass for COW'ed blocks so that lockdep doesn't complain. */ 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, }; struct btrfs_path; -- 2.24.1