From 7a6b1c8e47aea0fb1033f8beeefb40755067fdff Mon Sep 17 00:00:00 2001
From: Bananymous <bananymousosq@gmail.com>
Date: Sat, 1 Apr 2023 01:54:35 +0300
Subject: [PATCH] Kernel: Fix traversing back from mount points

---
 kernel/include/kernel/FS/VirtualFileSystem.h |  3 ++-
 kernel/kernel/FS/VirtualFileSystem.cpp       | 20 +++++++++++++++-----
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/kernel/include/kernel/FS/VirtualFileSystem.h b/kernel/include/kernel/FS/VirtualFileSystem.h
index 49e0b3243..d74bfcfba 100644
--- a/kernel/include/kernel/FS/VirtualFileSystem.h
+++ b/kernel/include/kernel/FS/VirtualFileSystem.h
@@ -35,7 +35,8 @@ namespace Kernel
 			File host;
 			FileSystem* target;
 		};
-		MountPoint* mount_point_for_inode(BAN::RefPtr<Inode>);
+		MountPoint* mount_from_host_inode(BAN::RefPtr<Inode>);
+		MountPoint* mount_from_root_inode(BAN::RefPtr<Inode>);
 
 	private:
 		SpinLock						m_lock;
diff --git a/kernel/kernel/FS/VirtualFileSystem.cpp b/kernel/kernel/FS/VirtualFileSystem.cpp
index 0ddb3d9a3..7549d1755 100644
--- a/kernel/kernel/FS/VirtualFileSystem.cpp
+++ b/kernel/kernel/FS/VirtualFileSystem.cpp
@@ -65,7 +65,7 @@ namespace Kernel
 		return {};
 	}
 
-	VirtualFileSystem::MountPoint* VirtualFileSystem::mount_point_for_inode(BAN::RefPtr<Inode> inode)
+	VirtualFileSystem::MountPoint* VirtualFileSystem::mount_from_host_inode(BAN::RefPtr<Inode> inode)
 	{
 		ASSERT(m_lock.is_locked());
 		for (MountPoint& mount : m_mount_points)
@@ -74,6 +74,15 @@ namespace Kernel
 		return nullptr;
 	}
 
+	VirtualFileSystem::MountPoint* VirtualFileSystem::mount_from_root_inode(BAN::RefPtr<Inode> inode)
+	{
+		ASSERT(m_lock.is_locked());
+		for (MountPoint& mount : m_mount_points)
+			if (*mount.target->root_inode() == *inode)
+				return &mount;
+		return nullptr;
+	}
+
 	BAN::ErrorOr<VirtualFileSystem::File> VirtualFileSystem::file_from_absolute_path(BAN::StringView path)
 	{
 		LockGuard _(m_lock);
@@ -96,13 +105,14 @@ namespace Kernel
 			}
 			else if (path_part == ".."sv)
 			{
-				if (auto* mount_point = mount_point_for_inode(inode))
+				if (auto* mount_point = mount_from_root_inode(inode))
 					inode = TRY(mount_point->host.inode->read_directory_inode(".."sv));
 				else
 					inode = TRY(inode->read_directory_inode(".."sv));
 
 				if (!canonical_path.empty())
 				{
+					ASSERT(canonical_path.front() == '/');
 					while (canonical_path.back() != '/')
 						canonical_path.pop_back();
 					canonical_path.pop_back();
@@ -113,10 +123,10 @@ namespace Kernel
 				inode = TRY(inode->read_directory_inode(path_part));
 				TRY(canonical_path.push_back('/'));
 				TRY(canonical_path.append(path_part));
-			}
 
-			if (auto* mount_point = mount_point_for_inode(inode))
-				inode = mount_point->target->root_inode();
+				if (auto* mount_point = mount_from_host_inode(inode))
+					inode = mount_point->target->root_inode();
+			}
 		}
 
 		if (canonical_path.empty())