Kernel: Deemphasize inode identifiers

These APIs were clearly modeled after Ext2FS internals, and make perfect sense
in Ext2FS context. The new APIs are more generic, and map better to the
semantics exported to the userspace, where inode identifiers only appear in
stat() and readdir() output, but never in any input.

This will also hopefully reduce the potential for races (see commit https://github.com/SerenityOS/serenity/commit/c44b4d61f350703fcf1bbd8f6e353b9c6c4210c2).

Lastly, this makes it way more viable to implement a filesystem that only
synthesizes its inodes lazily when queried, and destroys them when they are no
longer in use. With inode identifiers being used to reference inodes, the only
choice for such a filesystem is to persist any inode it has given out the
identifier for, because it might be queried at any later time. With direct
references to inodes, the filesystem will know when the last reference is
dropped and the inode can be safely destroyed.

1 files changed, 5 insertions, 5 deletions

diff --git a/Kernel/FileSystem/TmpFS.h b/Kernel/FileSystem/TmpFS.h
index b90aac1f47..a2bc5d8181 100644
--- a/Kernel/FileSystem/TmpFS.h
+++ b/Kernel/FileSystem/TmpFS.h
@@ -48,12 +48,9 @@ public:
 
     virtual bool supports_watchers() const override { return true; }
 
-    virtual InodeIdentifier root_inode() const override;
+    virtual NonnullRefPtr<Inode> root_inode() const override;
     virtual RefPtr<Inode> get_inode(InodeIdentifier) const override;
 
-    virtual KResultOr<NonnullRefPtr<Inode>> create_inode(InodeIdentifier parent_id, const String& name, mode_t, off_t size, dev_t, uid_t, gid_t) override;
-    virtual KResult create_directory(InodeIdentifier parent_id, const String& name, mode_t, uid_t, gid_t) override;
-
 private:
     TmpFS();
 
@@ -83,7 +80,8 @@ public:
     virtual RefPtr<Inode> lookup(StringView name) override;
     virtual void flush_metadata() override;
     virtual ssize_t write_bytes(off_t, ssize_t, const u8* buffer, FileDescription*) override;
-    virtual KResult add_child(InodeIdentifier child_id, const StringView& name, mode_t) override;
+    virtual KResultOr<NonnullRefPtr<Inode>> create_child(const String& name, mode_t, dev_t, uid_t, gid_t) override;
+    virtual KResult add_child(Inode&, const StringView& name, mode_t) override;
     virtual KResult remove_child(const StringView& name) override;
     virtual size_t directory_entry_count() const override;
     virtual KResult chmod(mode_t) override;
@@ -99,6 +97,8 @@ private:
     static NonnullRefPtr<TmpFSInode> create(TmpFS&, InodeMetadata metadata, InodeIdentifier parent);
     static NonnullRefPtr<TmpFSInode> create_root(TmpFS&);
 
+    void notify_watchers();
+
     InodeMetadata m_metadata;
     InodeIdentifier m_parent;