Kernel: Update atime/ctime/mtime timestamps atomically

Instead of having three separate APIs (one for each timestamp),
there's now only Inode::update_timestamps() and it takes 3x optional
timestamps. The non-empty timestamps are updated while holding the inode
mutex, and the outside world no longer has to look at intermediate
timestamp states.

Kernel/FileSystem/Ext2FileSystem.cpp

@@ -1537,34 +1537,23 @@ ErrorOr<NonnullLockRefPtr<Inode>> Ext2FSInode::lookup(StringView name)
     return fs().get_inode({ fsid(), inode_index });
 }
 
-ErrorOr<void> Ext2FSInode::set_atime(time_t t)
+ErrorOr<void> Ext2FSInode::update_timestamps(Optional<time_t> atime, Optional<time_t> ctime, Optional<time_t> mtime)
 {
     MutexLocker locker(m_inode_lock);
     if (fs().is_readonly())
         return EROFS;
-    if (t > INT32_MAX)
+    if (atime.value_or(0) > INT32_MAX)
         return EINVAL;
-    m_raw_inode.i_atime = t;
-    set_metadata_dirty(true);
-    return {};
-}
-
-ErrorOr<void> Ext2FSInode::set_ctime(time_t t)
-{
-    MutexLocker locker(m_inode_lock);
-    if (fs().is_readonly())
-        return EROFS;
-    m_raw_inode.i_ctime = t;
-    set_metadata_dirty(true);
-    return {};
-}
-
-ErrorOr<void> Ext2FSInode::set_mtime(time_t t)
-{
-    MutexLocker locker(m_inode_lock);
-    if (fs().is_readonly())
-        return EROFS;
-    m_raw_inode.i_mtime = t;
+    if (ctime.value_or(0) > INT32_MAX)
+        return EINVAL;
+    if (mtime.value_or(0) > INT32_MAX)
+        return EINVAL;
+    if (atime.has_value())
+        m_raw_inode.i_atime = atime.value();
+    if (ctime.has_value())
+        m_raw_inode.i_ctime = ctime.value();
+    if (mtime.has_value())
+        m_raw_inode.i_mtime = mtime.value();
     set_metadata_dirty(true);
     return {};
 }

Kernel/FileSystem/Ext2FileSystem.h

@@ -44,9 +44,7 @@ private:
     virtual ErrorOr<NonnullLockRefPtr<Inode>> create_child(StringView name, mode_t, dev_t, UserID, GroupID) override;
     virtual ErrorOr<void> add_child(Inode& child, StringView name, mode_t) override;
     virtual ErrorOr<void> remove_child(StringView name) override;
-    virtual ErrorOr<void> set_atime(time_t) override;
-    virtual ErrorOr<void> set_ctime(time_t) override;
-    virtual ErrorOr<void> set_mtime(time_t) override;
+    virtual ErrorOr<void> update_timestamps(Optional<time_t> atime, Optional<time_t> ctime, Optional<time_t> mtime) override;
     virtual ErrorOr<void> increment_link_count() override;
     virtual ErrorOr<void> decrement_link_count() override;
     virtual ErrorOr<void> chmod(mode_t) override;

Kernel/FileSystem/ISO9660FileSystem.cpp

@@ -528,17 +528,7 @@ ErrorOr<void> ISO9660Inode::truncate(u64)
     return EROFS;
 }
 
-ErrorOr<void> ISO9660Inode::set_atime(time_t)
-{
-    return EROFS;
-}
-
-ErrorOr<void> ISO9660Inode::set_ctime(time_t)
-{
-    return EROFS;
-}
-
-ErrorOr<void> ISO9660Inode::set_mtime(time_t)
+ErrorOr<void> ISO9660Inode::update_timestamps(Optional<time_t>, Optional<time_t>, Optional<time_t>)
 {
     return EROFS;
 }

Kernel/FileSystem/ISO9660FileSystem.h

@@ -359,9 +359,7 @@ public:
     virtual ErrorOr<void> chmod(mode_t) override;
     virtual ErrorOr<void> chown(UserID, GroupID) override;
     virtual ErrorOr<void> truncate(u64) override;
-    virtual ErrorOr<void> set_atime(time_t) override;
-    virtual ErrorOr<void> set_ctime(time_t) override;
-    virtual ErrorOr<void> set_mtime(time_t) override;
+    virtual ErrorOr<void> update_timestamps(Optional<time_t> atime, Optional<time_t> ctime, Optional<time_t> mtime) override;
 
 private:
     // HACK: The base ISO 9660 standard says the maximum filename length is 37

Kernel/FileSystem/Inode.cpp

@@ -106,17 +106,7 @@ void Inode::will_be_destroyed()
         (void)flush_metadata();
 }
 
-ErrorOr<void> Inode::set_atime(time_t)
-{
-    return ENOTIMPL;
-}
-
-ErrorOr<void> Inode::set_ctime(time_t)
-{
-    return ENOTIMPL;
-}
-
-ErrorOr<void> Inode::set_mtime(time_t)
+ErrorOr<void> Inode::update_timestamps([[maybe_unused]] Optional<time_t> atime, [[maybe_unused]] Optional<time_t> ctime, [[maybe_unused]] Optional<time_t> mtime)
 {
     return ENOTIMPL;
 }
@@ -236,8 +226,7 @@ void Inode::did_modify_contents()
     // FIXME: What happens if this fails?
     //        ENOTIMPL would be a meaningless error to return here
     auto time = kgettimeofday().to_truncated_seconds();
-    (void)set_mtime(time);
-    (void)set_ctime(time);
+    (void)update_timestamps({}, time, time);
 
     m_watchers.for_each([&](auto& watcher) {
         watcher->notify_inode_event({}, identifier(), InodeWatcherEvent::Type::ContentModified);

Kernel/FileSystem/Inode.h

@@ -80,9 +80,7 @@ public:
 
     bool is_metadata_dirty() const { return m_metadata_dirty; }
 
-    virtual ErrorOr<void> set_atime(time_t);
-    virtual ErrorOr<void> set_ctime(time_t);
-    virtual ErrorOr<void> set_mtime(time_t);
+    virtual ErrorOr<void> update_timestamps(Optional<time_t> atime, Optional<time_t> ctime, Optional<time_t> mtime);
     virtual ErrorOr<void> increment_link_count();
     virtual ErrorOr<void> decrement_link_count();
 

Kernel/FileSystem/InodeFile.cpp

@@ -49,7 +49,7 @@ ErrorOr<size_t> InodeFile::write(OpenFileDescription& description, u64 offset, U
         nwritten = TRY(m_inode->write_bytes(offset, count, data, &description));
     }
     if (nwritten > 0) {
-        auto mtime_result = m_inode->set_mtime(kgettimeofday().to_truncated_seconds());
+        auto mtime_result = m_inode->update_timestamps({}, {}, kgettimeofday().to_truncated_seconds());
         Thread::current()->did_file_write(nwritten);
         evaluate_block_conditions();
         if (mtime_result.is_error())
@@ -106,7 +106,7 @@ ErrorOr<NonnullOwnPtr<KString>> InodeFile::pseudo_path(OpenFileDescription const
 ErrorOr<void> InodeFile::truncate(u64 size)
 {
     TRY(m_inode->truncate(size));
-    TRY(m_inode->set_mtime(kgettimeofday().to_truncated_seconds()));
+    TRY(m_inode->update_timestamps({}, {}, kgettimeofday().to_truncated_seconds()));
     return {};
 }
 

Kernel/FileSystem/ProcFS.cpp

@@ -145,11 +145,6 @@ ErrorOr<void> ProcFSGlobalInode::truncate(u64 size)
     return m_associated_component->truncate(size);
 }
 
-ErrorOr<void> ProcFSGlobalInode::set_mtime(time_t time)
-{
-    return m_associated_component->set_mtime(time);
-}
-
 InodeMetadata ProcFSGlobalInode::metadata() const
 {
     MutexLocker locker(m_inode_lock);

Kernel/FileSystem/ProcFS.h

@@ -84,7 +84,6 @@ protected:
     virtual ErrorOr<void> traverse_as_directory(Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>) const override;
     virtual ErrorOr<NonnullLockRefPtr<Inode>> lookup(StringView) override;
     virtual ErrorOr<void> truncate(u64) override final;
-    virtual ErrorOr<void> set_mtime(time_t) override final;
 
     NonnullLockRefPtr<ProcFSExposedComponent> m_associated_component;
 };

Kernel/FileSystem/SysFS.cpp

@@ -121,11 +121,6 @@ ErrorOr<void> SysFSInode::chown(UserID, GroupID)
     return EPERM;
 }
 
-ErrorOr<void> SysFSInode::set_mtime(time_t time)
-{
-    return m_associated_component->set_mtime(time);
-}
-
 ErrorOr<void> SysFSInode::truncate(u64 size)
 {
     return m_associated_component->truncate(size);

Kernel/FileSystem/SysFS.h

@@ -54,7 +54,6 @@ protected:
     virtual ErrorOr<void> chmod(mode_t) override;
     virtual ErrorOr<void> chown(UserID, GroupID) override;
     virtual ErrorOr<void> truncate(u64) override;
-    virtual ErrorOr<void> set_mtime(time_t) override;
 
     virtual ErrorOr<void> attach(OpenFileDescription& description) override final;
     virtual void did_seek(OpenFileDescription&, off_t) override final;

Kernel/FileSystem/SysFS/Component.h

@@ -35,7 +35,6 @@ public:
     virtual mode_t permissions() const;
     virtual ErrorOr<void> truncate(u64) { return EPERM; }
     virtual size_t size() const { return 0; }
-    virtual ErrorOr<void> set_mtime(time_t) { return ENOTIMPL; }
     virtual ErrorOr<size_t> write_bytes(off_t, size_t, UserOrKernelBuffer const&, OpenFileDescription*) { return EROFS; }
     virtual ErrorOr<void> refresh_data(OpenFileDescription&) const { return {}; }
 

Kernel/FileSystem/SysFS/Subsystems/Firmware/PowerStateSwitch.h

@@ -27,7 +27,6 @@ public:
     virtual mode_t permissions() const override;
     virtual ErrorOr<size_t> write_bytes(off_t, size_t, UserOrKernelBuffer const&, OpenFileDescription*) override;
     virtual ErrorOr<void> truncate(u64) override;
-    virtual ErrorOr<void> set_mtime(time_t) override { return {}; }
 
 private:
     PowerStateSwitchNode(FirmwareSysFSDirectory&);

Kernel/FileSystem/TmpFS.cpp

@@ -301,29 +301,16 @@ ErrorOr<void> TmpFSInode::truncate(u64 size)
     return {};
 }
 
-ErrorOr<void> TmpFSInode::set_atime(time_t time)
+ErrorOr<void> TmpFSInode::update_timestamps(Optional<time_t> atime, Optional<time_t> ctime, Optional<time_t> mtime)
 {
     MutexLocker locker(m_inode_lock);
 
-    m_metadata.atime = time;
-    set_metadata_dirty(true);
-    return {};
-}
-
-ErrorOr<void> TmpFSInode::set_ctime(time_t time)
-{
-    MutexLocker locker(m_inode_lock);
-
-    m_metadata.ctime = time;
-    set_metadata_dirty(true);
-    return {};
-}
-
-ErrorOr<void> TmpFSInode::set_mtime(time_t t)
-{
-    MutexLocker locker(m_inode_lock);
-
-    m_metadata.mtime = t;
+    if (atime.has_value())
+        m_metadata.atime = atime.value();
+    if (ctime.has_value())
+        m_metadata.ctime = ctime.value();
+    if (mtime.has_value())
+        m_metadata.ctime = mtime.value();
     set_metadata_dirty(true);
     return {};
 }

Kernel/FileSystem/TmpFS.h

@@ -59,9 +59,7 @@ public:
     virtual ErrorOr<void> chmod(mode_t) override;
     virtual ErrorOr<void> chown(UserID, GroupID) override;
     virtual ErrorOr<void> truncate(u64) override;
-    virtual ErrorOr<void> set_atime(time_t) override;
-    virtual ErrorOr<void> set_ctime(time_t) override;
-    virtual ErrorOr<void> set_mtime(time_t) override;
+    virtual ErrorOr<void> update_timestamps(Optional<time_t> atime, Optional<time_t> ctime, Optional<time_t> mtime) override;
 
 private:
     TmpFSInode(TmpFS& fs, InodeMetadata const& metadata, LockWeakPtr<TmpFSInode> parent);

Kernel/FileSystem/VirtualFileSystem.cpp

@@ -213,8 +213,7 @@ ErrorOr<void> VirtualFileSystem::utime(Credentials const& credentials, StringVie
     if (custody->is_readonly())
         return EROFS;
 
-    TRY(inode.set_atime(atime));
-    TRY(inode.set_mtime(mtime));
+    TRY(inode.update_timestamps(atime, {}, mtime));
     return {};
 }
 
@@ -228,10 +227,10 @@ ErrorOr<void> VirtualFileSystem::utimensat(Credentials const& credentials, Strin
         return EROFS;
 
     // NOTE: A standard ext2 inode cannot store nanosecond timestamps.
-    if (atime.tv_nsec != UTIME_OMIT)
-        TRY(inode.set_atime(atime.tv_sec));
-    if (mtime.tv_nsec != UTIME_OMIT)
-        TRY(inode.set_mtime(mtime.tv_sec));
+    TRY(inode.update_timestamps(
+        (atime.tv_nsec != UTIME_OMIT) ? atime.tv_nsec : Optional<time_t> {},
+        {},
+        (mtime.tv_nsec != UTIME_OMIT) ? mtime.tv_nsec : Optional<time_t> {}));
 
     return {};
 }
@@ -321,7 +320,7 @@ ErrorOr<NonnullLockRefPtr<OpenFileDescription>> VirtualFileSystem::open(Credenti
 
     if (should_truncate_file) {
         TRY(inode.truncate(0));
-        TRY(inode.set_mtime(kgettimeofday().to_truncated_seconds()));
+        TRY(inode.update_timestamps({}, {}, kgettimeofday().to_truncated_seconds()));
     }
     auto description = TRY(OpenFileDescription::try_create(custody));
     description->set_rw_mode(options);

Kernel/ProcessExposed.cpp

@@ -184,11 +184,6 @@ ErrorOr<void> ProcFSSystemBoolean::truncate(u64 size)
     return {};
 }
 
-ErrorOr<void> ProcFSSystemBoolean::set_mtime(time_t)
-{
-    return {};
-}
-
 ErrorOr<size_t> ProcFSExposedLink::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, OpenFileDescription*) const
 {
     VERIFY(offset == 0);

Kernel/ProcessExposed.h

@@ -74,7 +74,6 @@ public:
     virtual ErrorOr<NonnullLockRefPtr<ProcFSExposedComponent>> lookup(StringView) { VERIFY_NOT_REACHED(); };
     virtual ErrorOr<size_t> write_bytes(off_t, size_t, UserOrKernelBuffer const&, OpenFileDescription*) { return EROFS; }
     virtual ErrorOr<void> truncate(u64) { return EPERM; }
-    virtual ErrorOr<void> set_mtime(time_t) { return ENOTIMPL; }
 
     virtual mode_t required_mode() const { return 0444; }
     virtual UserID owner_user() const { return 0; }
@@ -201,7 +200,6 @@ private:
     virtual ErrorOr<size_t> write_bytes(off_t, size_t, UserOrKernelBuffer const&, OpenFileDescription*) override final;
     virtual mode_t required_mode() const override final { return 0644; }
     virtual ErrorOr<void> truncate(u64) override final;
-    virtual ErrorOr<void> set_mtime(time_t) override final;
 };
 
 }