diff mbox series

[06/12] btrfs: introduce BTRFS_NESTING_LEFT/RIGHT_COW

Message ID a228e8b88622403f98fcb46d5e7d4a4746192483.1597938191.git.josef@toxicpanda.com (mailing list archive)
State New, archived
Headers show
Series Convert btree locking to an rwsem | expand

Commit Message

Josef Bacik Aug. 20, 2020, 3:46 p.m. UTC 
For similar reasons as BTRFS_NESTING_COW, we need
BTRFS_NESTING_LEFT/RIGHT_COW.  The pattern is this

lock leaf -> BTRFS_NESTING_NORMAL
  cow leaf -> BTRFS_NESTING_COW
    split leaf
      lock left -> BTRFS_NESTING_LEFT
        cow left -> BTRFS_NESTING_LEFT_COW

We need this in order to indicate to lockdep that these locks are
discrete and are being taken in a safe order.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/ctree.c   | 12 ++++++------
 fs/btrfs/locking.h |  8 ++++++++
 2 files changed, 14 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index a4b2439a398a..ae5e3f1056d8 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1900,7 +1900,7 @@  static noinline int balance_level(struct btrfs_trans_handle *trans,
 		btrfs_set_lock_blocking_write(left);
 		wret = btrfs_cow_block(trans, root, left,
 				       parent, pslot - 1, &left,
-				       BTRFS_NESTING_COW);
+				       BTRFS_NESTING_LEFT_COW);
 		if (wret) {
 			ret = wret;
 			goto enospc;
@@ -1916,7 +1916,7 @@  static noinline int balance_level(struct btrfs_trans_handle *trans,
 		btrfs_set_lock_blocking_write(right);
 		wret = btrfs_cow_block(trans, root, right,
 				       parent, pslot + 1, &right,
-				       BTRFS_NESTING_COW);
+				       BTRFS_NESTING_RIGHT_COW);
 		if (wret) {
 			ret = wret;
 			goto enospc;
@@ -2085,7 +2085,7 @@  static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
 		} else {
 			ret = btrfs_cow_block(trans, root, left, parent,
 					      pslot - 1, &left,
-					      BTRFS_NESTING_COW);
+					      BTRFS_NESTING_LEFT_COW);
 			if (ret)
 				wret = 1;
 			else {
@@ -2140,7 +2140,7 @@  static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
 		} else {
 			ret = btrfs_cow_block(trans, root, right,
 					      parent, pslot + 1,
-					      &right, BTRFS_NESTING_COW);
+					      &right, BTRFS_NESTING_RIGHT_COW);
 			if (ret)
 				wret = 1;
 			else {
@@ -3751,7 +3751,7 @@  static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
 
 	/* cow and double check */
 	ret = btrfs_cow_block(trans, root, right, upper,
-			      slot + 1, &right, BTRFS_NESTING_COW);
+			      slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
 	if (ret)
 		goto out_unlock;
 
@@ -3987,7 +3987,7 @@  static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
 	/* cow and double check */
 	ret = btrfs_cow_block(trans, root, left,
 			      path->nodes[1], slot - 1, &left,
-			      BTRFS_NESTING_COW);
+			      BTRFS_NESTING_LEFT_COW);
 	if (ret) {
 		/* we hit -ENOSPC, but it isn't fatal here */
 		if (ret == -ENOSPC)
diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h
index 3169c2bb6db9..a88c6f59f616 100644
--- a/fs/btrfs/locking.h
+++ b/fs/btrfs/locking.h
@@ -39,6 +39,14 @@  enum btrfs_lock_nesting {
 	BTRFS_NESTING_LEFT,
 	BTRFS_NESTING_RIGHT,
 
+	/*
+	 * When splitting we will be holding a lock on the left/right node when
+	 * we need to cow that node, thus we need a new set of subclasses for
+	 * these two operations.
+	 */
+	BTRFS_NESTING_LEFT_COW,
+	BTRFS_NESTING_RIGHT_COW,
+
 	/*
 	 * 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