From 2f37cef1e414c296b7ee3ea2a1dc19554838d2d2 Mon Sep 17 00:00:00 2001
From: Augustin Cavalier <waddlesplash@gmail.com>
Date: Mon, 18 Nov 2024 13:27:31 -0500
Subject: [PATCH] kernel/fs: Use DoublyLinkedList for the unused vnodes list.

Avoids needing a nonstandard "offsetof", and inlines more methods.
No behavioral change intended.

Also rename "next" to "hash_next" for clarity, and remove an unused
"next" field from LockWaiter.
---
 src/system/kernel/fs/Vnode.h         |  5 ++---
 src/system/kernel/fs/unused_vnodes.h | 10 ++++++----
 src/system/kernel/fs/vfs.cpp         | 11 +++--------
 3 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/src/system/kernel/fs/Vnode.h b/src/system/kernel/fs/Vnode.h
index 6efe921a5c..c223e01a29 100644
--- a/src/system/kernel/fs/Vnode.h
+++ b/src/system/kernel/fs/Vnode.h
@@ -24,14 +24,14 @@ typedef struct vnode Vnode;
 
 
 struct vnode : fs_vnode, DoublyLinkedListLinkImpl<vnode> {
-			struct vnode*		next;
+			struct vnode*		hash_next;
 			VMCache*			cache;
 			struct fs_mount*	mount;
 			struct vnode*		covered_by;
 			struct vnode*		covers;
 			struct advisory_locking* advisory_locking;
 			struct file_descriptor* mandatory_locked_by;
-			list_link			unused_link;
+			DoublyLinkedListLink<struct vnode> unused_link;
 			ino_t				id;
 			dev_t				device;
 			int32				ref_count;
@@ -83,7 +83,6 @@ private:
 	static	const uint32		kBucketCount		= 32;
 
 			struct LockWaiter : DoublyLinkedListLinkImpl<LockWaiter> {
-				LockWaiter*		next;
 				Thread*			thread;
 				struct vnode*	vnode;
 			};
diff --git a/src/system/kernel/fs/unused_vnodes.h b/src/system/kernel/fs/unused_vnodes.h
index 5f5bb490b6..e15860700b 100644
--- a/src/system/kernel/fs/unused_vnodes.h
+++ b/src/system/kernel/fs/unused_vnodes.h
@@ -29,7 +29,9 @@ const static uint32 kMaxUnusedVnodes = 8192;
 	Innermost lock. Must not be held when acquiring any other lock.
 */
 static mutex sUnusedVnodesLock = MUTEX_INITIALIZER("unused vnodes");
-static list sUnusedVnodeList;
+typedef DoublyLinkedList<Vnode, DoublyLinkedListMemberGetLink<Vnode, &Vnode::unused_link> >
+	UnusedVnodeList;
+static UnusedVnodeList sUnusedVnodeList;
 static uint32 sUnusedVnodes = 0;
 
 static const int32 kMaxHotVnodes = 1024;
@@ -56,7 +58,7 @@ flush_hot_vnodes_locked()
 
 		if (vnode->IsHot()) {
 			if (vnode->IsUnused()) {
-				list_add_item(&sUnusedVnodeList, vnode);
+				sUnusedVnodeList.Add(vnode);
 				sUnusedVnodes++;
 			}
 			vnode->SetHot(false);
@@ -146,7 +148,7 @@ vnode_used(Vnode* vnode)
 
 	if (!vnode->IsHot()) {
 		MutexLocker unusedLocker(sUnusedVnodesLock);
-		list_remove_item(&sUnusedVnodeList, vnode);
+		sUnusedVnodeList.Remove(vnode);
 		sUnusedVnodes--;
 	}
 }
@@ -174,7 +176,7 @@ vnode_to_be_freed(Vnode* vnode)
 		}
 	} else if (vnode->IsUnused()) {
 		MutexLocker unusedLocker(sUnusedVnodesLock);
-		list_remove_item(&sUnusedVnodeList, vnode);
+		sUnusedVnodeList.Remove(vnode);
 		sUnusedVnodes--;
 	}
 
diff --git a/src/system/kernel/fs/vfs.cpp b/src/system/kernel/fs/vfs.cpp
index 5728620f13..55719b8aa5 100644
--- a/src/system/kernel/fs/vfs.cpp
+++ b/src/system/kernel/fs/vfs.cpp
@@ -291,7 +291,7 @@ struct VnodeHash {
 
 	ValueType*& GetLink(ValueType* value) const
 	{
-		return value->next;
+		return value->hash_next;
 	}
 };
 
@@ -1319,8 +1319,7 @@ free_unused_vnodes(int32 level)
 
 		// get the first node
 		MutexLocker unusedVnodesLocker(sUnusedVnodesLock);
-		struct vnode* vnode = (struct vnode*)list_get_first_item(
-			&sUnusedVnodeList);
+		struct vnode* vnode = sUnusedVnodeList.First();
 		unusedVnodesLocker.Unlock();
 
 		if (vnode == NULL)
@@ -1336,7 +1335,7 @@ free_unused_vnodes(int32 level)
 		// has been touched in the meantime, i.e. it is no longer the least
 		// recently used unused vnode and we rather don't free it.
 		unusedVnodesLocker.Lock();
-		if (vnode != list_get_first_item(&sUnusedVnodeList))
+		if (vnode != sUnusedVnodeList.First())
 			continue;
 		unusedVnodesLocker.Unlock();
 
@@ -5262,10 +5261,6 @@ vfs_init(kernel_args* args)
 	if (sVnodeTable == NULL || sVnodeTable->Init(VNODE_HASH_TABLE_SIZE) != B_OK)
 		panic("vfs_init: error creating vnode hash table\n");
 
-	struct vnode dummy_vnode;
-	list_init_etc(&sUnusedVnodeList, offset_of_member(dummy_vnode, unused_link));
-
-	struct fs_mount dummyMount;
 	sMountsTable = new(std::nothrow) MountTable();
 	if (sMountsTable == NULL
 			|| sMountsTable->Init(MOUNTS_HASH_TABLE_SIZE) != B_OK)