Kernel: Make a copy of the dirty inode list before iterating in sync().

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/6b581aff773

Kernel/Ext2FileSystem.cpp

@@ -20,7 +20,6 @@ Retained<Ext2FS> Ext2FS::create(Retained<DiskDevice>&& device)
 
 Ext2FS::Ext2FS(Retained<DiskDevice>&& device)
     : DiskBackedFS(move(device))
-    , m_lock("Ext2FS")
 {
 }
 

Kernel/Ext2FileSystem.h

@@ -133,7 +133,6 @@ private:
     mutable ByteBuffer m_cached_super_block;
     mutable ByteBuffer m_cached_group_descriptor_table;
 
-    mutable Lock m_lock;
     mutable HashMap<BlockIndex, RetainPtr<Ext2FSInode>> m_inode_cache;
 };
 

Kernel/FileSystem.cpp

@@ -25,7 +25,8 @@ HashTable<Inode*>& all_inodes()
 }
 
 FS::FS()
-    : m_fsid(++s_lastFileSystemID)
+    : m_lock("FS")
+    , m_fsid(++s_lastFileSystemID)
 {
     all_fses().set(m_fsid, this);
 }
@@ -143,9 +144,18 @@ int Inode::decrement_link_count()
 
 void FS::sync()
 {
-    for (auto* inode : all_inodes()) {
-        if (inode->is_metadata_dirty())
-            inode->flush_metadata();
+    Vector<Retained<Inode>> inodes;
+    {
+        InterruptDisabler disabler;
+        for (auto* inode : all_inodes()) {
+            if (inode->is_metadata_dirty())
+                inodes.unchecked_append(*inode);
+        }
+    }
+
+    for (auto& inode : inodes) {
+        ASSERT(inode->is_metadata_dirty());
+        inode->flush_metadata();
     }
 }
 

Kernel/FileSystem.h

@@ -25,6 +25,7 @@ class LocalSocket;
 class VMObject;
 
 class FS : public Retainable<FS> {
+    friend class Inode;
 public:
     virtual ~FS();
 
@@ -60,6 +61,8 @@ public:
 protected:
     FS();
 
+    mutable Lock m_lock;
+
 private:
     unsigned m_fsid { 0 };
     bool m_readonly { false };
@@ -67,6 +70,7 @@ private:
 
 class Inode : public Retainable<Inode> {
     friend class VFS;
+    friend class FS;
 public:
     virtual ~Inode();
 

Kernel/SyntheticFileSystem.cpp

@@ -11,7 +11,6 @@ Retained<SynthFS> SynthFS::create()
 }
 
 SynthFS::SynthFS()
-    : m_lock("SynthFS")
 {
 }
 

Kernel/SyntheticFileSystem.h

@@ -37,7 +37,6 @@ protected:
 private:
     InodeIndex m_next_inode_index { 2 };
     HashMap<InodeIndex, RetainPtr<SynthFSInode>> m_inodes;
-    mutable Lock m_lock;
 };
 
 struct SynthFSInodeCustomData {