[16/18] btrfs: add comments regarding locking to struct btrfs_delayed_ref_root

Commit Message

Filipe Manana Oct. 24, 2024, 4:24 p.m. UTC

From: Filipe Manana <[e-mail]>

Add some comments to struct btrfs_delayed_ref_root's fields to mention
what its spinlock protects.

Signed-off-by: Filipe Manana <[e-mail]>
---
 fs/btrfs/delayed-ref.h | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

Patch

diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
index c3749e6cc374..0a9f4d7dd87b 100644
--- a/fs/btrfs/delayed-ref.h
+++ b/fs/btrfs/delayed-ref.h
@@ -213,19 +213,33 @@  struct btrfs_delayed_ref_root {
 	 */
 	struct xarray dirty_extents;
 
-	/* this spin lock protects the rbtree and the entries inside */
+	/*
+	 * Protects the rbtree href_root, its entries and the following fields:
+	 * num_heads, num_heads_ready, pending_csums and run_delayed_start.
+	 */
 	spinlock_t lock;
 
-	/* total number of head nodes in tree */
+	/* Total number of head refs, protected by the spinlock 'lock'. */
 	unsigned long num_heads;
 
-	/* total number of head nodes ready for processing */
+	/*
+	 * Total number of head refs ready for processing, protected by the
+	 * spinlock 'lock'.
+	 */
 	unsigned long num_heads_ready;
 
+	/*
+	 * Track space reserved for deleting csums of data extents.
+	 * Protected by the spinlock 'lock'.
+	 */
 	u64 pending_csums;
 
 	unsigned long flags;
 
+	/*
+	 * Track from which bytenr to start searching ref heads.
+	 * Protected by the spinlock 'lock'.
+	 */
 	u64 run_delayed_start;
 
 	/*