btrfs.c

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/* Copyright (c) Mark Harmstone 2016-17
 *
 * This file is part of WinBtrfs.
 *
 * WinBtrfs is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public Licence as published by
 * the Free Software Foundation, either version 3 of the Licence, or
 * (at your option) any later version.
 *
 * WinBtrfs is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public Licence for more details.
 *
 * You should have received a copy of the GNU Lesser General Public Licence
 * along with WinBtrfs.  If not, see <http://www.gnu.org/licenses/>. */

#ifdef _DEBUG
#define DEBUG
#endif

#include "btrfs_drv.h"
#ifndef __REACTOS__
#ifndef _MSC_VER
#include <cpuid.h>
#else
#include <intrin.h>
#endif
#endif
#include <ntddscsi.h>
#include "btrfs.h"
#include <ata.h>

#ifndef _MSC_VER
#include <initguid.h>
#include <ntddstor.h>
#undef INITGUID
#endif

#include <ntdddisk.h>
#include <ntddvol.h>

#ifdef _MSC_VER
#include <initguid.h>
#include <ntddstor.h>
#undef INITGUID
#endif

#ifdef _MSC_VER
#include <ntstrsafe.h>
#else
NTSTATUS RtlStringCbVPrintfA(char* pszDest, size_t cbDest, const char* pszFormat, va_list argList); // not in mingw
#endif

#define INCOMPAT_SUPPORTED (BTRFS_INCOMPAT_FLAGS_MIXED_BACKREF | BTRFS_INCOMPAT_FLAGS_DEFAULT_SUBVOL | BTRFS_INCOMPAT_FLAGS_MIXED_GROUPS | \
                            BTRFS_INCOMPAT_FLAGS_COMPRESS_LZO | BTRFS_INCOMPAT_FLAGS_BIG_METADATA | BTRFS_INCOMPAT_FLAGS_RAID56 | \
                            BTRFS_INCOMPAT_FLAGS_EXTENDED_IREF | BTRFS_INCOMPAT_FLAGS_SKINNY_METADATA | BTRFS_INCOMPAT_FLAGS_NO_HOLES | \
                            BTRFS_INCOMPAT_FLAGS_COMPRESS_ZSTD)
#define COMPAT_RO_SUPPORTED (BTRFS_COMPAT_RO_FLAGS_FREE_SPACE_CACHE | BTRFS_COMPAT_RO_FLAGS_FREE_SPACE_CACHE_VALID)

static const WCHAR device_name[] = {'\\','B','t','r','f','s',0};
static const WCHAR dosdevice_name[] = {'\\','D','o','s','D','e','v','i','c','e','s','\\','B','t','r','f','s',0};

DEFINE_GUID(BtrfsBusInterface, 0x4d414874, 0x6865, 0x6761, 0x6d, 0x65, 0x83, 0x69, 0x17, 0x9a, 0x7d, 0x1d);

PDRIVER_OBJECT drvobj;
PDEVICE_OBJECT master_devobj, busobj;
#ifndef __REACTOS__
bool have_sse42 = false, have_sse2 = false;
#endif
uint64_t num_reads = 0;
LIST_ENTRY uid_map_list, gid_map_list;
LIST_ENTRY VcbList;
ERESOURCE global_loading_lock;
uint32_t debug_log_level = 0;
uint32_t mount_compress = 0;
uint32_t mount_compress_force = 0;
uint32_t mount_compress_type = 0;
uint32_t mount_zlib_level = 3;
uint32_t mount_zstd_level = 3;
uint32_t mount_flush_interval = 30;
uint32_t mount_max_inline = 2048;
uint32_t mount_skip_balance = 0;
uint32_t mount_no_barrier = 0;
uint32_t mount_no_trim = 0;
uint32_t mount_clear_cache = 0;
uint32_t mount_allow_degraded = 0;
uint32_t mount_readonly = 0;
uint32_t mount_no_root_dir = 0;
uint32_t no_pnp = 0;
bool log_started = false;
UNICODE_STRING log_device, log_file, registry_path;
tPsUpdateDiskCounters fPsUpdateDiskCounters;
tCcCopyReadEx fCcCopyReadEx;
tCcCopyWriteEx fCcCopyWriteEx;
tCcSetAdditionalCacheAttributesEx fCcSetAdditionalCacheAttributesEx;
tFsRtlUpdateDiskCounters fFsRtlUpdateDiskCounters;
tIoUnregisterPlugPlayNotificationEx fIoUnregisterPlugPlayNotificationEx;
tFsRtlGetEcpListFromIrp fFsRtlGetEcpListFromIrp;
tFsRtlGetNextExtraCreateParameter fFsRtlGetNextExtraCreateParameter;
tFsRtlValidateReparsePointBuffer fFsRtlValidateReparsePointBuffer;
tFsRtlCheckLockForOplockRequest fFsRtlCheckLockForOplockRequest;
tFsRtlAreThereCurrentOrInProgressFileLocks fFsRtlAreThereCurrentOrInProgressFileLocks;
bool diskacc = false;
void *notification_entry = NULL, *notification_entry2 = NULL, *notification_entry3 = NULL;
ERESOURCE pdo_list_lock, mapping_lock;
LIST_ENTRY pdo_list;
bool finished_probing = false;
HANDLE degraded_wait_handle = NULL, mountmgr_thread_handle = NULL;
bool degraded_wait = true;
KEVENT mountmgr_thread_event;
bool shutting_down = false;
ERESOURCE boot_lock;

#ifdef _DEBUG
PFILE_OBJECT comfo = NULL;
PDEVICE_OBJECT comdo = NULL;
HANDLE log_handle = NULL;
ERESOURCE log_lock;
HANDLE serial_thread_handle = NULL;

static void init_serial(bool first_time);
#endif

static NTSTATUS close_file(_In_ PFILE_OBJECT FileObject, _In_ PIRP Irp);

typedef struct {
    KEVENT Event;
    IO_STATUS_BLOCK iosb;
} read_context;

// no longer in Windows headers??
extern BOOLEAN WdmlibRtlIsNtDdiVersionAvailable(ULONG Version);

#ifdef _DEBUG
_Function_class_(IO_COMPLETION_ROUTINE)
static NTSTATUS __stdcall dbg_completion(_In_ PDEVICE_OBJECT DeviceObject, _In_ PIRP Irp, _In_ PVOID conptr) {
    read_context* context = conptr;

    UNUSED(DeviceObject);

    context->iosb = Irp->IoStatus;
    KeSetEvent(&context->Event, 0, false);

    return STATUS_MORE_PROCESSING_REQUIRED;
}

#define DEBUG_MESSAGE_LEN 1024

#ifdef DEBUG_LONG_MESSAGES
void _debug_message(_In_ const char* func, _In_ const char* file, _In_ unsigned int line, _In_ char* s, ...) {
#else
void _debug_message(_In_ const char* func, _In_ char* s, ...) {
#endif
    LARGE_INTEGER offset;
    PIO_STACK_LOCATION IrpSp;
    NTSTATUS Status;
    PIRP Irp;
    va_list ap;
    char *buf2, *buf;
    read_context context;
    uint32_t length;

    buf2 = ExAllocatePoolWithTag(NonPagedPool, DEBUG_MESSAGE_LEN, ALLOC_TAG);

    if (!buf2) {
        DbgPrint("Couldn't allocate buffer in debug_message\n");
        return;
    }

#ifdef DEBUG_LONG_MESSAGES
    sprintf(buf2, "%p:%s:%s:%u:", PsGetCurrentThread(), func, file, line);
#else
    sprintf(buf2, "%p:%s:", PsGetCurrentThread(), func);
#endif
    buf = &buf2[strlen(buf2)];

    va_start(ap, s);

    RtlStringCbVPrintfA(buf, DEBUG_MESSAGE_LEN - strlen(buf2), s, ap);

    ExAcquireResourceSharedLite(&log_lock, true);

    if (!log_started || (log_device.Length == 0 && log_file.Length == 0)) {
        DbgPrint(buf2);
    } else if (log_device.Length > 0) {
        if (!comdo) {
            DbgPrint(buf2);
            goto exit2;
        }

        length = (uint32_t)strlen(buf2);

        offset.u.LowPart = 0;
        offset.u.HighPart = 0;

        RtlZeroMemory(&context, sizeof(read_context));

        KeInitializeEvent(&context.Event, NotificationEvent, false);

        Irp = IoAllocateIrp(comdo->StackSize, false);

        if (!Irp) {
            DbgPrint("IoAllocateIrp failed\n");
            goto exit2;
        }

        IrpSp = IoGetNextIrpStackLocation(Irp);
        IrpSp->MajorFunction = IRP_MJ_WRITE;
        IrpSp->FileObject = comfo;

        if (comdo->Flags & DO_BUFFERED_IO) {
            Irp->AssociatedIrp.SystemBuffer = buf2;

            Irp->Flags = IRP_BUFFERED_IO;
        } else if (comdo->Flags & DO_DIRECT_IO) {
            Irp->MdlAddress = IoAllocateMdl(buf2, length, false, false, NULL);
            if (!Irp->MdlAddress) {
                DbgPrint("IoAllocateMdl failed\n");
                goto exit;
            }

            MmBuildMdlForNonPagedPool(Irp->MdlAddress);
        } else {
            Irp->UserBuffer = buf2;
        }

        IrpSp->Parameters.Write.Length = length;
        IrpSp->Parameters.Write.ByteOffset = offset;

        Irp->UserIosb = &context.iosb;

        Irp->UserEvent = &context.Event;

        IoSetCompletionRoutine(Irp, dbg_completion, &context, true, true, true);

        Status = IoCallDriver(comdo, Irp);

        if (Status == STATUS_PENDING) {
            KeWaitForSingleObject(&context.Event, Executive, KernelMode, false, NULL);
            Status = context.iosb.Status;
        }

        if (comdo->Flags & DO_DIRECT_IO)
            IoFreeMdl(Irp->MdlAddress);

        if (!NT_SUCCESS(Status)) {
            DbgPrint("failed to write to COM1 - error %08x\n", Status);
            goto exit;
        }

exit:
        IoFreeIrp(Irp);
    } else if (log_handle != NULL) {
        IO_STATUS_BLOCK iosb;

        length = (uint32_t)strlen(buf2);

        Status = ZwWriteFile(log_handle, NULL, NULL, NULL, &iosb, buf2, length, NULL, NULL);

        if (!NT_SUCCESS(Status)) {
            DbgPrint("failed to write to file - error %08x\n", Status);
        }
    }

exit2:
    ExReleaseResourceLite(&log_lock);

    va_end(ap);

    if (buf2)
        ExFreePool(buf2);
}
#endif

bool is_top_level(_In_ PIRP Irp) {
    if (!IoGetTopLevelIrp()) {
        IoSetTopLevelIrp(Irp);
        return true;
    }

    return false;
}

_Function_class_(DRIVER_UNLOAD)
static void __stdcall DriverUnload(_In_ PDRIVER_OBJECT DriverObject) {
    UNICODE_STRING dosdevice_nameW;

    TRACE("(%p)\n", DriverObject);

    dosdevice_nameW.Buffer = (WCHAR*)dosdevice_name;
    dosdevice_nameW.Length = dosdevice_nameW.MaximumLength = sizeof(dosdevice_name) - sizeof(WCHAR);

    IoDeleteSymbolicLink(&dosdevice_nameW);
    IoDeleteDevice(DriverObject->DeviceObject);

    while (!IsListEmpty(&uid_map_list)) {
        LIST_ENTRY* le = RemoveHeadList(&uid_map_list);
        uid_map* um = CONTAINING_RECORD(le, uid_map, listentry);

        ExFreePool(um->sid);

        ExFreePool(um);
    }

    while (!IsListEmpty(&gid_map_list)) {
        gid_map* gm = CONTAINING_RECORD(RemoveHeadList(&gid_map_list), gid_map, listentry);

        ExFreePool(gm->sid);
        ExFreePool(gm);
    }

    // FIXME - free volumes and their devpaths

#ifdef _DEBUG
    if (comfo)
        ObDereferenceObject(comfo);

    if (log_handle)
        ZwClose(log_handle);
#endif

    ExDeleteResourceLite(&global_loading_lock);
    ExDeleteResourceLite(&pdo_list_lock);

    if (log_device.Buffer)
        ExFreePool(log_device.Buffer);

    if (log_file.Buffer)
        ExFreePool(log_file.Buffer);

    if (registry_path.Buffer)
        ExFreePool(registry_path.Buffer);

#ifdef _DEBUG
    ExDeleteResourceLite(&log_lock);
#endif
    ExDeleteResourceLite(&mapping_lock);
}

static bool get_last_inode(_In_ _Requires_exclusive_lock_held_(_Curr_->tree_lock) device_extension* Vcb, _In_ root* r, _In_opt_ PIRP Irp) {
    KEY searchkey;
    traverse_ptr tp, prev_tp;
    NTSTATUS Status;

    // get last entry
    searchkey.obj_id = 0xffffffffffffffff;
    searchkey.obj_type = 0xff;
    searchkey.offset = 0xffffffffffffffff;

    Status = find_item(Vcb, r, &tp, &searchkey, false, Irp);
    if (!NT_SUCCESS(Status)) {
        ERR("error - find_item returned %08x\n", Status);
        return false;
    }

    if (tp.item->key.obj_type == TYPE_INODE_ITEM || (tp.item->key.obj_type == TYPE_ROOT_ITEM && !(tp.item->key.obj_id & 0x8000000000000000))) {
        r->lastinode = tp.item->key.obj_id;
        TRACE("last inode for tree %I64x is %I64x\n", r->id, r->lastinode);
        return true;
    }

    while (find_prev_item(Vcb, &tp, &prev_tp, Irp)) {
        tp = prev_tp;

        TRACE("moving on to %I64x,%x,%I64x\n", tp.item->key.obj_id, tp.item->key.obj_type, tp.item->key.offset);

        if (tp.item->key.obj_type == TYPE_INODE_ITEM || (tp.item->key.obj_type == TYPE_ROOT_ITEM && !(tp.item->key.obj_id & 0x8000000000000000))) {
            r->lastinode = tp.item->key.obj_id;
            TRACE("last inode for tree %I64x is %I64x\n", r->id, r->lastinode);
            return true;
        }
    }

    r->lastinode = SUBVOL_ROOT_INODE;

    WARN("no INODE_ITEMs in tree %I64x\n", r->id);

    return true;
}

_Success_(return)
static bool extract_xattr(_In_reads_bytes_(size) void* item, _In_ USHORT size, _In_z_ char* name, _Out_ uint8_t** data, _Out_ uint16_t* datalen) {
    DIR_ITEM* xa = (DIR_ITEM*)item;
    USHORT xasize;

    while (true) {
        if (size < sizeof(DIR_ITEM) || size < (sizeof(DIR_ITEM) - 1 + xa->m + xa->n)) {
            WARN("DIR_ITEM is truncated\n");
            return false;
        }

        if (xa->n == strlen(name) && RtlCompareMemory(name, xa->name, xa->n) == xa->n) {
            TRACE("found xattr %s\n", name);

            *datalen = xa->m;

            if (xa->m > 0) {
                *data = ExAllocatePoolWithTag(PagedPool, xa->m, ALLOC_TAG);
                if (!*data) {
                    ERR("out of memory\n");
                    return false;
                }

                RtlCopyMemory(*data, &xa->name[xa->n], xa->m);
            } else
                *data = NULL;

            return true;
        }

        xasize = sizeof(DIR_ITEM) - 1 + xa->m + xa->n;

        if (size > xasize) {
            size -= xasize;
            xa = (DIR_ITEM*)&xa->name[xa->m + xa->n];
        } else
            break;
    }

    TRACE("xattr %s not found\n", name);

    return false;
}

_Success_(return)
bool get_xattr(_In_ _Requires_lock_held_(_Curr_->tree_lock) device_extension* Vcb, _In_ root* subvol, _In_ uint64_t inode, _In_z_ char* name, _In_ uint32_t crc32,
               _Out_ uint8_t** data, _Out_ uint16_t* datalen, _In_opt_ PIRP Irp) {
    KEY searchkey;
    traverse_ptr tp;
    NTSTATUS Status;

    TRACE("(%p, %I64x, %I64x, %s, %08x, %p, %p)\n", Vcb, subvol->id, inode, name, crc32, data, datalen);

    searchkey.obj_id = inode;
    searchkey.obj_type = TYPE_XATTR_ITEM;
    searchkey.offset = crc32;

    Status = find_item(Vcb, subvol, &tp, &searchkey, false, Irp);
    if (!NT_SUCCESS(Status)) {
        ERR("error - find_item returned %08x\n", Status);
        return false;
    }

    if (keycmp(tp.item->key, searchkey)) {
        TRACE("could not find item (%I64x,%x,%I64x)\n", searchkey.obj_id, searchkey.obj_type, searchkey.offset);
        return false;
    }

    if (tp.item->size < sizeof(DIR_ITEM)) {
        ERR("(%I64x,%x,%I64x) was %u bytes, expected at least %u\n", tp.item->key.obj_id, tp.item->key.obj_type, tp.item->key.offset, tp.item->size, sizeof(DIR_ITEM));
        return false;
    }

    return extract_xattr(tp.item->data, tp.item->size, name, data, datalen);
}

_Dispatch_type_(IRP_MJ_CLOSE)
_Function_class_(DRIVER_DISPATCH)
static NTSTATUS __stdcall drv_close(_In_ PDEVICE_OBJECT DeviceObject, _In_ PIRP Irp) {
    NTSTATUS Status;
    PIO_STACK_LOCATION IrpSp;
    device_extension* Vcb = DeviceObject->DeviceExtension;
    bool top_level;

    FsRtlEnterFileSystem();

    TRACE("close\n");

    top_level = is_top_level(Irp);

    if (DeviceObject == master_devobj) {
        TRACE("Closing file system\n");
        Status = STATUS_SUCCESS;
        goto end;
    } else if (Vcb && Vcb->type == VCB_TYPE_VOLUME) {
        Status = vol_close(DeviceObject, Irp);
        goto end;
    } else if (!Vcb || Vcb->type != VCB_TYPE_FS) {
        Status = STATUS_INVALID_PARAMETER;
        goto end;
    }

    IrpSp = IoGetCurrentIrpStackLocation(Irp);

    // FIXME - call FsRtlNotifyUninitializeSync(&Vcb->NotifySync) if unmounting

    Status = close_file(IrpSp->FileObject, Irp);

end:
    Irp->IoStatus.Status = Status;
    Irp->IoStatus.Information = 0;

    IoCompleteRequest( Irp, IO_DISK_INCREMENT );

    if (top_level)
        IoSetTopLevelIrp(NULL);

    TRACE("returning %08x\n", Status);

    FsRtlExitFileSystem();

    return Status;
}

_Dispatch_type_(IRP_MJ_FLUSH_BUFFERS)
_Function_class_(DRIVER_DISPATCH)
static NTSTATUS __stdcall drv_flush_buffers(_In_ PDEVICE_OBJECT DeviceObject, _In_ PIRP Irp) {
    NTSTATUS Status;
    PIO_STACK_LOCATION IrpSp = IoGetCurrentIrpStackLocation( Irp );
    PFILE_OBJECT FileObject = IrpSp->FileObject;
    fcb* fcb = FileObject->FsContext;
    device_extension* Vcb = DeviceObject->DeviceExtension;
    bool top_level;

    FsRtlEnterFileSystem();

    TRACE("flush buffers\n");

    top_level = is_top_level(Irp);

    if (Vcb && Vcb->type == VCB_TYPE_VOLUME) {
        Status = vol_flush_buffers(DeviceObject, Irp);
        goto end;
    } else if (!Vcb || Vcb->type != VCB_TYPE_FS) {
        Status = STATUS_SUCCESS;
        goto end;
    }

    if (!fcb) {
        ERR("fcb was NULL\n");
        Status = STATUS_SUCCESS;
        goto end;
    }

    if (fcb == Vcb->volume_fcb) {
        Status = STATUS_SUCCESS;
        goto end;
    }

    FsRtlCheckOplock(fcb_oplock(fcb), Irp, NULL, NULL, NULL);

    Irp->IoStatus.Information = 0;

    fcb->Header.IsFastIoPossible = fast_io_possible(fcb);

    Status = STATUS_SUCCESS;
    Irp->IoStatus.Status = Status;

    if (fcb->type != BTRFS_TYPE_DIRECTORY) {
        CcFlushCache(FileObject->SectionObjectPointer, NULL, 0, &Irp->IoStatus);

        if (fcb->Header.PagingIoResource) {
            ExAcquireResourceExclusiveLite(fcb->Header.PagingIoResource, true);
            ExReleaseResourceLite(fcb->Header.PagingIoResource);
        }

        Status = Irp->IoStatus.Status;
    }

end:
    IoCompleteRequest(Irp, IO_NO_INCREMENT);

    TRACE("returning %08x\n", Status);

    if (top_level)
        IoSetTopLevelIrp(NULL);

    FsRtlExitFileSystem();

    return Status;
}

static void calculate_total_space(_In_ device_extension* Vcb, _Out_ uint64_t* totalsize, _Out_ uint64_t* freespace) {
    uint64_t nfactor, dfactor, sectors_used;

    if (Vcb->data_flags & BLOCK_FLAG_DUPLICATE || Vcb->data_flags & BLOCK_FLAG_RAID1 || Vcb->data_flags & BLOCK_FLAG_RAID10) {
        nfactor = 1;
        dfactor = 2;
    } else if (Vcb->data_flags & BLOCK_FLAG_RAID5) {
        nfactor = Vcb->superblock.num_devices - 1;
        dfactor = Vcb->superblock.num_devices;
    } else if (Vcb->data_flags & BLOCK_FLAG_RAID6) {
        nfactor = Vcb->superblock.num_devices - 2;
        dfactor = Vcb->superblock.num_devices;
    } else {
        nfactor = 1;
        dfactor = 1;
    }

    sectors_used = Vcb->superblock.bytes_used / Vcb->superblock.sector_size;

    *totalsize = (Vcb->superblock.total_bytes / Vcb->superblock.sector_size) * nfactor / dfactor;
    *freespace = sectors_used > *totalsize ? 0 : (*totalsize - sectors_used);
}

#ifndef __REACTOS__
#define INIT_UNICODE_STRING(var, val) UNICODE_STRING us##var; us##var.Buffer = (WCHAR*)val; us##var.Length = us##var.MaximumLength = sizeof(val) - sizeof(WCHAR);

// This function exists because we have to lie about our FS type in certain situations.
// MPR!MprGetConnection queries the FS type, and compares it to a whitelist. If it doesn't match,
// it will return ERROR_NO_NET_OR_BAD_PATH, which prevents UAC from working.
// The command mklink refuses to create hard links on anything other than NTFS, so we have to
// blacklist cmd.exe too.

static bool lie_about_fs_type() {
    NTSTATUS Status;
    PROCESS_BASIC_INFORMATION pbi;
    PPEB peb;
    LIST_ENTRY* le;
    ULONG retlen;
#ifdef _AMD64_
    ULONG_PTR wow64info;
#endif

    INIT_UNICODE_STRING(mpr, L"MPR.DLL");
    INIT_UNICODE_STRING(cmd, L"CMD.EXE");
    INIT_UNICODE_STRING(fsutil, L"FSUTIL.EXE");
    INIT_UNICODE_STRING(storsvc, L"STORSVC.DLL");

    if (!PsGetCurrentProcess())
        return false;

#ifdef _AMD64_
    Status = ZwQueryInformationProcess(NtCurrentProcess(), ProcessWow64Information, &wow64info, sizeof(wow64info), NULL);

    if (NT_SUCCESS(Status) && wow64info != 0)
        return true;
#endif

    Status = ZwQueryInformationProcess(NtCurrentProcess(), ProcessBasicInformation, &pbi, sizeof(pbi), &retlen);

    if (!NT_SUCCESS(Status)) {
        ERR("ZwQueryInformationProcess returned %08x\n", Status);
        return false;
    }

    if (!pbi.PebBaseAddress)
        return false;

    peb = pbi.PebBaseAddress;

    if (!peb->Ldr)
        return false;

    le = peb->Ldr->InMemoryOrderModuleList.Flink;
    while (le != &peb->Ldr->InMemoryOrderModuleList) {
        LDR_DATA_TABLE_ENTRY* entry = CONTAINING_RECORD(le, LDR_DATA_TABLE_ENTRY, InMemoryOrderLinks);
        bool blacklist = false;

        if (entry->FullDllName.Length >= usmpr.Length) {
            UNICODE_STRING name;

            name.Buffer = &entry->FullDllName.Buffer[(entry->FullDllName.Length - usmpr.Length) / sizeof(WCHAR)];
            name.Length = name.MaximumLength = usmpr.Length;

            blacklist = FsRtlAreNamesEqual(&name, &usmpr, true, NULL);
        }

        if (!blacklist && entry->FullDllName.Length >= uscmd.Length) {
            UNICODE_STRING name;

            name.Buffer = &entry->FullDllName.Buffer[(entry->FullDllName.Length - uscmd.Length) / sizeof(WCHAR)];
            name.Length = name.MaximumLength = uscmd.Length;

            blacklist = FsRtlAreNamesEqual(&name, &uscmd, true, NULL);
        }

        if (!blacklist && entry->FullDllName.Length >= usfsutil.Length) {
            UNICODE_STRING name;

            name.Buffer = &entry->FullDllName.Buffer[(entry->FullDllName.Length - usfsutil.Length) / sizeof(WCHAR)];
            name.Length = name.MaximumLength = usfsutil.Length;

            blacklist = FsRtlAreNamesEqual(&name, &usfsutil, true, NULL);
        }

        if (!blacklist && entry->FullDllName.Length >= usstorsvc.Length) {
            UNICODE_STRING name;

            name.Buffer = &entry->FullDllName.Buffer[(entry->FullDllName.Length - usstorsvc.Length) / sizeof(WCHAR)];
            name.Length = name.MaximumLength = usstorsvc.Length;

            blacklist = FsRtlAreNamesEqual(&name, &usstorsvc, true, NULL);
        }

        if (blacklist) {
            void** frames;
            ULONG i, num_frames;

            frames = ExAllocatePoolWithTag(PagedPool, 256 * sizeof(void*), ALLOC_TAG);
            if (!frames) {
                ERR("out of memory\n");
                return false;
            }

            num_frames = RtlWalkFrameChain(frames, 256, 1);

            for (i = 0; i < num_frames; i++) {
                // entry->Reserved3[1] appears to be the image size
                if (frames[i] >= entry->DllBase && (ULONG_PTR)frames[i] <= (ULONG_PTR)entry->DllBase + (ULONG_PTR)entry->Reserved3[1]) {
                    ExFreePool(frames);
                    return true;
                }
            }

            ExFreePool(frames);
        }

        le = le->Flink;
    }

    return false;
}
#endif

// version of RtlUTF8ToUnicodeN for Vista and below
NTSTATUS utf8_to_utf16(WCHAR* dest, ULONG dest_max, ULONG* dest_len, char* src, ULONG src_len) {
    NTSTATUS Status = STATUS_SUCCESS;
    uint8_t* in = (uint8_t*)src;
    uint16_t* out = (uint16_t*)dest;
    ULONG needed = 0, left = dest_max / sizeof(uint16_t);
#ifdef __REACTOS__
    ULONG i;

    for (i = 0; i < src_len; ++i) {
#else

    for (ULONG i = 0; i < src_len; i++) {
#endif
        uint32_t cp;

        if (!(in[i] & 0x80))
            cp = in[i];
        else if ((in[i] & 0xe0) == 0xc0) {
            if (i == src_len - 1 || (in[i+1] & 0xc0) != 0x80) {
                cp = 0xfffd;
                Status = STATUS_SOME_NOT_MAPPED;
            } else {
                cp = ((in[i] & 0x1f) << 6) | (in[i+1] & 0x3f);
                i++;
            }
        } else if ((in[i] & 0xf0) == 0xe0) {
            if (i >= src_len - 2 || (in[i+1] & 0xc0) != 0x80 || (in[i+2] & 0xc0) != 0x80) {
                cp = 0xfffd;
                Status = STATUS_SOME_NOT_MAPPED;
            } else {
                cp = ((in[i] & 0xf) << 12) | ((in[i+1] & 0x3f) << 6) | (in[i+2] & 0x3f);
                i += 2;
            }
        } else if ((in[i] & 0xf8) == 0xf0) {
            if (i >= src_len - 3 || (in[i+1] & 0xc0) != 0x80 || (in[i+2] & 0xc0) != 0x80 || (in[i+3] & 0xc0) != 0x80) {
                cp = 0xfffd;
                Status = STATUS_SOME_NOT_MAPPED;
            } else {
                cp = ((in[i] & 0x7) << 18) | ((in[i+1] & 0x3f) << 12) | ((in[i+2] & 0x3f) << 6) | (in[i+3] & 0x3f);
                i += 3;
            }
        } else {
            cp = 0xfffd;
            Status = STATUS_SOME_NOT_MAPPED;
        }

        if (cp > 0x10ffff) {
            cp = 0xfffd;
            Status = STATUS_SOME_NOT_MAPPED;
        }

        if (dest) {
            if (cp <= 0xffff) {
                if (left < 1)
                    return STATUS_BUFFER_OVERFLOW;

                *out = (uint16_t)cp;
                out++;

                left--;
            } else {
                if (left < 2)
                    return STATUS_BUFFER_OVERFLOW;

                cp -= 0x10000;

                *out = 0xd800 | ((cp & 0xffc00) >> 10);
                out++;

                *out = 0xdc00 | (cp & 0x3ff);
                out++;

                left -= 2;
            }
        }

        if (cp <= 0xffff)
            needed += sizeof(uint16_t);
        else
            needed += 2 * sizeof(uint16_t);
    }

    if (dest_len)
        *dest_len = needed;

    return Status;
}

// version of RtlUnicodeToUTF8N for Vista and below
NTSTATUS utf16_to_utf8(char* dest, ULONG dest_max, ULONG* dest_len, WCHAR* src, ULONG src_len) {
    NTSTATUS Status = STATUS_SUCCESS;
    uint16_t* in = (uint16_t*)src;
    uint8_t* out = (uint8_t*)dest;
    ULONG in_len = src_len / sizeof(uint16_t);
    ULONG needed = 0, left = dest_max;
#ifdef __REACTOS__
    ULONG i = 0;

    for (i = 0; i < in_len; i++) {
#else

    for (ULONG i = 0; i < in_len; i++) {
#endif
        uint32_t cp = *in;
        in++;

        if ((cp & 0xfc00) == 0xd800) {
            if (i == in_len - 1 || (*in & 0xfc00) != 0xdc00) {
                cp = 0xfffd;
                Status = STATUS_SOME_NOT_MAPPED;
            } else {
                cp = (cp & 0x3ff) << 10;
                cp |= *in & 0x3ff;
                cp += 0x10000;

                in++;
                i++;
            }
        } else if ((cp & 0xfc00) == 0xdc00) {
            cp = 0xfffd;
            Status = STATUS_SOME_NOT_MAPPED;
        }

        if (cp > 0x10ffff) {
            cp = 0xfffd;
            Status = STATUS_SOME_NOT_MAPPED;
        }

        if (dest) {
            if (cp < 0x80) {
                if (left < 1)
                    return STATUS_BUFFER_OVERFLOW;

                *out = (uint8_t)cp;
                out++;

                left--;
            } else if (cp < 0x800) {
                if (left < 2)
                    return STATUS_BUFFER_OVERFLOW;

                *out = 0xc0 | ((cp & 0x7c0) >> 6);
                out++;

                *out = 0x80 | (cp & 0x3f);
                out++;

                left -= 2;
            } else if (cp < 0x10000) {
                if (left < 3)
                    return STATUS_BUFFER_OVERFLOW;

                *out = 0xe0 | ((cp & 0xf000) >> 12);
                out++;

                *out = 0x80 | ((cp & 0xfc0) >> 6);
                out++;

                *out = 0x80 | (cp & 0x3f);
                out++;

                left -= 3;
            } else {
                if (left < 4)
                    return STATUS_BUFFER_OVERFLOW;

                *out = 0xf0 | ((cp & 0x1c0000) >> 18);
                out++;

                *out = 0x80 | ((cp & 0x3f000) >> 12);
                out++;

                *out = 0x80 | ((cp & 0xfc0) >> 6);
                out++;

                *out = 0x80 | (cp & 0x3f);
                out++;

                left -= 4;
            }
        }

        if (cp < 0x80)
            needed++;
        else if (cp < 0x800)
            needed += 2;
        else if (cp < 0x10000)
            needed += 3;
        else
            needed += 4;
    }

    if (dest_len)
        *dest_len = needed;

    return Status;
}

_Dispatch_type_(IRP_MJ_QUERY_VOLUME_INFORMATION)
_Function_class_(DRIVER_DISPATCH)
static NTSTATUS __stdcall drv_query_volume_information(_In_ PDEVICE_OBJECT DeviceObject, _In_ PIRP Irp) {
    PIO_STACK_LOCATION IrpSp;
    NTSTATUS Status;
    ULONG BytesCopied = 0;
    device_extension* Vcb = DeviceObject->DeviceExtension;
    bool top_level;

    FsRtlEnterFileSystem();

    TRACE("query volume information\n");
    top_level = is_top_level(Irp);

    if (Vcb && Vcb->type == VCB_TYPE_VOLUME) {
        Status = vol_query_volume_information(DeviceObject, Irp);
        goto end;
    } else if (!Vcb || Vcb->type != VCB_TYPE_FS) {
        Status = STATUS_INVALID_PARAMETER;
        goto end;
    }

    IrpSp = IoGetCurrentIrpStackLocation(Irp);

    Status = STATUS_NOT_IMPLEMENTED;

    switch (IrpSp->Parameters.QueryVolume.FsInformationClass) {
        case FileFsAttributeInformation:
        {
            FILE_FS_ATTRIBUTE_INFORMATION* data = Irp->AssociatedIrp.SystemBuffer;
            bool overflow = false;
#ifndef __REACTOS__
            static const WCHAR ntfs[] = L"NTFS";
#endif
            static const WCHAR btrfs[] = L"Btrfs";
            const WCHAR* fs_name;
            ULONG fs_name_len, orig_fs_name_len;

#ifndef __REACTOS__
            if (Irp->RequestorMode == UserMode && lie_about_fs_type()) {
                fs_name = ntfs;
                orig_fs_name_len = fs_name_len = sizeof(ntfs) - sizeof(WCHAR);
            } else {
                fs_name = btrfs;
                orig_fs_name_len = fs_name_len = sizeof(btrfs) - sizeof(WCHAR);
            }
#else
            fs_name = btrfs;
            orig_fs_name_len = fs_name_len = sizeof(btrfs) - sizeof(WCHAR);
#endif

            TRACE("FileFsAttributeInformation\n");

            if (IrpSp->Parameters.QueryVolume.Length < sizeof(FILE_FS_ATTRIBUTE_INFORMATION) - sizeof(WCHAR) + fs_name_len) {
                if (IrpSp->Parameters.QueryVolume.Length > sizeof(FILE_FS_ATTRIBUTE_INFORMATION) - sizeof(WCHAR))
                    fs_name_len = IrpSp->Parameters.QueryVolume.Length - sizeof(FILE_FS_ATTRIBUTE_INFORMATION) + sizeof(WCHAR);
                else
                    fs_name_len = 0;

                overflow = true;
            }

            data->FileSystemAttributes = FILE_CASE_PRESERVED_NAMES | FILE_CASE_SENSITIVE_SEARCH |
                                         FILE_UNICODE_ON_DISK | FILE_NAMED_STREAMS | FILE_SUPPORTS_HARD_LINKS | FILE_PERSISTENT_ACLS |
                                         FILE_SUPPORTS_REPARSE_POINTS | FILE_SUPPORTS_SPARSE_FILES | FILE_SUPPORTS_OBJECT_IDS |
                                         FILE_SUPPORTS_OPEN_BY_FILE_ID | FILE_SUPPORTS_EXTENDED_ATTRIBUTES | FILE_SUPPORTS_BLOCK_REFCOUNTING |
                                         FILE_SUPPORTS_POSIX_UNLINK_RENAME;
            if (Vcb->readonly)
                data->FileSystemAttributes |= FILE_READ_ONLY_VOLUME;

            // should also be FILE_FILE_COMPRESSION when supported
            data->MaximumComponentNameLength = 255; // FIXME - check
            data->FileSystemNameLength = orig_fs_name_len;
            RtlCopyMemory(data->FileSystemName, fs_name, fs_name_len);

            BytesCopied = sizeof(FILE_FS_ATTRIBUTE_INFORMATION) - sizeof(WCHAR) + fs_name_len;
            Status = overflow ? STATUS_BUFFER_OVERFLOW : STATUS_SUCCESS;
            break;
        }

        case FileFsDeviceInformation:
        {
            FILE_FS_DEVICE_INFORMATION* ffdi = Irp->AssociatedIrp.SystemBuffer;

            TRACE("FileFsDeviceInformation\n");

            ffdi->DeviceType = FILE_DEVICE_DISK;

            ExAcquireResourceSharedLite(&Vcb->tree_lock, true);
            ffdi->Characteristics = Vcb->Vpb->RealDevice->Characteristics;
            ExReleaseResourceLite(&Vcb->tree_lock);

            if (Vcb->readonly)
                ffdi->Characteristics |= FILE_READ_ONLY_DEVICE;
            else
                ffdi->Characteristics &= ~FILE_READ_ONLY_DEVICE;

            BytesCopied = sizeof(FILE_FS_DEVICE_INFORMATION);
            Status = STATUS_SUCCESS;

            break;
        }

        case FileFsFullSizeInformation:
        {
            FILE_FS_FULL_SIZE_INFORMATION* ffsi = Irp->AssociatedIrp.SystemBuffer;

            TRACE("FileFsFullSizeInformation\n");

            calculate_total_space(Vcb, (uint64_t*)&ffsi->TotalAllocationUnits.QuadPart, (uint64_t*)&ffsi->ActualAvailableAllocationUnits.QuadPart);
            ffsi->CallerAvailableAllocationUnits.QuadPart = ffsi->ActualAvailableAllocationUnits.QuadPart;
            ffsi->SectorsPerAllocationUnit = Vcb->superblock.sector_size / 512;
            ffsi->BytesPerSector = 512;

            BytesCopied = sizeof(FILE_FS_FULL_SIZE_INFORMATION);
            Status = STATUS_SUCCESS;

            break;
        }

        case FileFsObjectIdInformation:
        {
            FILE_FS_OBJECTID_INFORMATION* ffoi = Irp->AssociatedIrp.SystemBuffer;

            TRACE("FileFsObjectIdInformation\n");

            RtlCopyMemory(ffoi->ObjectId, &Vcb->superblock.uuid.uuid[0], sizeof(UCHAR) * 16);
            RtlZeroMemory(ffoi->ExtendedInfo, sizeof(ffoi->ExtendedInfo));

            BytesCopied = sizeof(FILE_FS_OBJECTID_INFORMATION);
            Status = STATUS_SUCCESS;

            break;
        }

        case FileFsSizeInformation:
        {
            FILE_FS_SIZE_INFORMATION* ffsi = Irp->AssociatedIrp.SystemBuffer;

            TRACE("FileFsSizeInformation\n");

            calculate_total_space(Vcb, (uint64_t*)&ffsi->TotalAllocationUnits.QuadPart, (uint64_t*)&ffsi->AvailableAllocationUnits.QuadPart);
            ffsi->SectorsPerAllocationUnit = Vcb->superblock.sector_size / 512;
            ffsi->BytesPerSector = 512;

            BytesCopied = sizeof(FILE_FS_SIZE_INFORMATION);
            Status = STATUS_SUCCESS;

            break;
        }

        case FileFsVolumeInformation:
        {
            FILE_FS_VOLUME_INFORMATION* data = Irp->AssociatedIrp.SystemBuffer;
            FILE_FS_VOLUME_INFORMATION ffvi;
            bool overflow = false;
            ULONG label_len, orig_label_len;

            TRACE("FileFsVolumeInformation\n");
            TRACE("max length = %u\n", IrpSp->Parameters.QueryVolume.Length);

            ExAcquireResourceSharedLite(&Vcb->tree_lock, true);

            Status = utf8_to_utf16(NULL, 0, &label_len, Vcb->superblock.label, (ULONG)strlen(Vcb->superblock.label));
            if (!NT_SUCCESS(Status)) {
                ERR("utf8_to_utf16 returned %08x\n", Status);
                ExReleaseResourceLite(&Vcb->tree_lock);
                break;
            }

            orig_label_len = label_len;

            if (IrpSp->Parameters.QueryVolume.Length < sizeof(FILE_FS_VOLUME_INFORMATION) - sizeof(WCHAR) + label_len) {
                if (IrpSp->Parameters.QueryVolume.Length > sizeof(FILE_FS_VOLUME_INFORMATION) - sizeof(WCHAR))
                    label_len = IrpSp->Parameters.QueryVolume.Length - sizeof(FILE_FS_VOLUME_INFORMATION) + sizeof(WCHAR);
                else
                    label_len = 0;

                overflow = true;
            }

            TRACE("label_len = %u\n", label_len);

            ffvi.VolumeCreationTime.QuadPart = 0; // FIXME
            ffvi.VolumeSerialNumber = Vcb->superblock.uuid.uuid[12] << 24 | Vcb->superblock.uuid.uuid[13] << 16 | Vcb->superblock.uuid.uuid[14] << 8 | Vcb->superblock.uuid.uuid[15];
            ffvi.VolumeLabelLength = orig_label_len;
            ffvi.SupportsObjects = false;

            RtlCopyMemory(data, &ffvi, min(sizeof(FILE_FS_VOLUME_INFORMATION) - sizeof(WCHAR), IrpSp->Parameters.QueryVolume.Length));

            if (label_len > 0) {
                ULONG bytecount;

                Status = utf8_to_utf16(&data->VolumeLabel[0], label_len, &bytecount, Vcb->superblock.label, (ULONG)strlen(Vcb->superblock.label));
                if (!NT_SUCCESS(Status) && Status != STATUS_BUFFER_TOO_SMALL) {
                    ERR("utf8_to_utf16 returned %08x\n", Status);
                    ExReleaseResourceLite(&Vcb->tree_lock);
                    break;
                }

                TRACE("label = %.*S\n", label_len / sizeof(WCHAR), data->VolumeLabel);
            }

            ExReleaseResourceLite(&Vcb->tree_lock);

            BytesCopied = sizeof(FILE_FS_VOLUME_INFORMATION) - sizeof(WCHAR) + label_len;
            Status = overflow ? STATUS_BUFFER_OVERFLOW : STATUS_SUCCESS;
            break;
        }

#ifndef __REACTOS__
#ifdef _MSC_VER // not in mingw yet
        case FileFsSectorSizeInformation:
        {
            FILE_FS_SECTOR_SIZE_INFORMATION* data = Irp->AssociatedIrp.SystemBuffer;

            data->LogicalBytesPerSector = Vcb->superblock.sector_size;
            data->PhysicalBytesPerSectorForAtomicity = Vcb->superblock.sector_size;
            data->PhysicalBytesPerSectorForPerformance = Vcb->superblock.sector_size;
            data->FileSystemEffectivePhysicalBytesPerSectorForAtomicity = Vcb->superblock.sector_size;
            data->ByteOffsetForSectorAlignment = 0;
            data->ByteOffsetForPartitionAlignment = 0;

            data->Flags = SSINFO_FLAGS_ALIGNED_DEVICE | SSINFO_FLAGS_PARTITION_ALIGNED_ON_DEVICE;

            if (Vcb->trim && !Vcb->options.no_trim)
                data->Flags |= SSINFO_FLAGS_TRIM_ENABLED;

            BytesCopied = sizeof(FILE_FS_SECTOR_SIZE_INFORMATION);

            break;
        }
#endif
#endif /* __REACTOS__ */

        default:
            Status = STATUS_INVALID_PARAMETER;
            WARN("unknown FsInformationClass %u\n", IrpSp->Parameters.QueryVolume.FsInformationClass);
            break;
    }

    if (!NT_SUCCESS(Status) && Status != STATUS_BUFFER_OVERFLOW)
        Irp->IoStatus.Information = 0;
    else
        Irp->IoStatus.Information = BytesCopied;

end:
    Irp->IoStatus.Status = Status;

    IoCompleteRequest( Irp, IO_DISK_INCREMENT );

    if (top_level)
        IoSetTopLevelIrp(NULL);

    TRACE("query volume information returning %08x\n", Status);

    FsRtlExitFileSystem();

    return Status;
}

_Function_class_(IO_COMPLETION_ROUTINE)
static NTSTATUS __stdcall read_completion(_In_ PDEVICE_OBJECT DeviceObject, _In_ PIRP Irp, _In_ PVOID conptr) {
    read_context* context = conptr;

    UNUSED(DeviceObject);

    context->iosb = Irp->IoStatus;
    KeSetEvent(&context->Event, 0, false);

    return STATUS_MORE_PROCESSING_REQUIRED;
}

NTSTATUS create_root(_In_ _Requires_exclusive_lock_held_(_Curr_->tree_lock) device_extension* Vcb, _In_ uint64_t id,
                     _Out_ root** rootptr, _In_ bool no_tree, _In_ uint64_t offset, _In_opt_ PIRP Irp) {
    NTSTATUS Status;
    root* r;
    tree* t = NULL;
    ROOT_ITEM* ri;
    traverse_ptr tp;

    r = ExAllocatePoolWithTag(PagedPool, sizeof(root), ALLOC_TAG);
    if (!r) {
        ERR("out of memory\n");
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    r->nonpaged = ExAllocatePoolWithTag(NonPagedPool, sizeof(root_nonpaged), ALLOC_TAG);
    if (!r->nonpaged) {
        ERR("out of memory\n");
        ExFreePool(r);
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    if (!no_tree) {
        t = ExAllocatePoolWithTag(PagedPool, sizeof(tree), ALLOC_TAG);
        if (!t) {
            ERR("out of memory\n");
            ExFreePool(r->nonpaged);
            ExFreePool(r);
            return STATUS_INSUFFICIENT_RESOURCES;
        }

        t->nonpaged = NULL;

        t->is_unique = true;
        t->uniqueness_determined = true;
        t->buf = NULL;
    }

    ri = ExAllocatePoolWithTag(PagedPool, sizeof(ROOT_ITEM), ALLOC_TAG);
    if (!ri) {
        ERR("out of memory\n");

        if (t)
            ExFreePool(t);

        ExFreePool(r->nonpaged);
        ExFreePool(r);
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    r->id = id;
    r->treeholder.address = 0;
    r->treeholder.generation = Vcb->superblock.generation;
    r->treeholder.tree = t;
    r->lastinode = 0;
    r->dirty = false;
    r->received = false;
    r->reserved = NULL;
    r->parent = 0;
    r->send_ops = 0;
    RtlZeroMemory(&r->root_item, sizeof(ROOT_ITEM));
    r->root_item.num_references = 1;
    r->fcbs_version = 0;
    r->checked_for_orphans = true;
    InitializeListHead(&r->fcbs);
    RtlZeroMemory(r->fcbs_ptrs, sizeof(LIST_ENTRY*) * 256);

    RtlCopyMemory(ri, &r->root_item, sizeof(ROOT_ITEM));

    // We ask here for a traverse_ptr to the item we're inserting, so we can
    // copy some of the tree's variables

    Status = insert_tree_item(Vcb, Vcb->root_root, id, TYPE_ROOT_ITEM, offset, ri, sizeof(ROOT_ITEM), &tp, Irp);
    if (!NT_SUCCESS(Status)) {
        ERR("insert_tree_item returned %08x\n", Status);
        ExFreePool(ri);

        if (t)
            ExFreePool(t);

        ExFreePool(r->nonpaged);
        ExFreePool(r);
        return Status;
    }

    ExInitializeResourceLite(&r->nonpaged->load_tree_lock);

    InsertTailList(&Vcb->roots, &r->list_entry);

    if (!no_tree) {
        RtlZeroMemory(&t->header, sizeof(tree_header));
        t->header.fs_uuid = tp.tree->header.fs_uuid;
        t->header.address = 0;
        t->header.flags = HEADER_FLAG_MIXED_BACKREF | 1; // 1 == "written"? Why does the Linux driver record this?
        t->header.chunk_tree_uuid = tp.tree->header.chunk_tree_uuid;
        t->header.generation = Vcb->superblock.generation;
        t->header.tree_id = id;
        t->header.num_items = 0;
        t->header.level = 0;

        t->has_address = false;
        t->size = 0;
        t->Vcb = Vcb;
        t->parent = NULL;
        t->paritem = NULL;
        t->root = r;

        InitializeListHead(&t->itemlist);

        t->new_address = 0;
        t->has_new_address = false;
        t->updated_extents = false;

        InsertTailList(&Vcb->trees, &t->list_entry);
        t->list_entry_hash.Flink = NULL;

        t->write = true;
        Vcb->need_write = true;
    }

    *rootptr = r;

    return STATUS_SUCCESS;
}

static NTSTATUS set_label(_In_ device_extension* Vcb, _In_ FILE_FS_LABEL_INFORMATION* ffli) {
    ULONG utf8len;
    NTSTATUS Status;
    ULONG vollen, i;

    TRACE("label = %.*S\n", ffli->VolumeLabelLength / sizeof(WCHAR), ffli->VolumeLabel);

    vollen = ffli->VolumeLabelLength;

    for (i = 0; i < ffli->VolumeLabelLength / sizeof(WCHAR); i++) {
        if (ffli->VolumeLabel[i] == 0) {
            vollen = i * sizeof(WCHAR);
            break;
        } else if (ffli->VolumeLabel[i] == '/' || ffli->VolumeLabel[i] == '\\') {
            Status = STATUS_INVALID_VOLUME_LABEL;
            goto end;
        }
    }

    if (vollen == 0) {
        utf8len = 0;
    } else {
        Status = utf16_to_utf8(NULL, 0, &utf8len, ffli->VolumeLabel, vollen);
        if (!NT_SUCCESS(Status))
            goto end;

        if (utf8len > MAX_LABEL_SIZE) {
            Status = STATUS_INVALID_VOLUME_LABEL;
            goto end;
        }
    }

    ExAcquireResourceExclusiveLite(&Vcb->tree_lock, true);

    if (utf8len > 0) {
        Status = utf16_to_utf8((PCHAR)&Vcb->superblock.label, MAX_LABEL_SIZE, &utf8len, ffli->VolumeLabel, vollen);
        if (!NT_SUCCESS(Status))
            goto release;
    } else
        Status = STATUS_SUCCESS;

    if (utf8len < MAX_LABEL_SIZE)
        RtlZeroMemory(Vcb->superblock.label + utf8len, MAX_LABEL_SIZE - utf8len);

    Vcb->need_write = true;

release:
    ExReleaseResourceLite(&Vcb->tree_lock);

end:
    TRACE("returning %08x\n", Status);

    return Status;
}

_Dispatch_type_(IRP_MJ_SET_VOLUME_INFORMATION)
_Function_class_(DRIVER_DISPATCH)
static NTSTATUS __stdcall drv_set_volume_information(_In_ PDEVICE_OBJECT DeviceObject, _In_ PIRP Irp) {
    PIO_STACK_LOCATION IrpSp = IoGetCurrentIrpStackLocation(Irp);
    device_extension* Vcb = DeviceObject->DeviceExtension;
    NTSTATUS Status;
    bool top_level;

    FsRtlEnterFileSystem();

    TRACE("set volume information\n");

    top_level = is_top_level(Irp);

    if (Vcb && Vcb->type == VCB_TYPE_VOLUME) {
        Status = vol_set_volume_information(DeviceObject, Irp);
        goto end;
    } else if (!Vcb || Vcb->type != VCB_TYPE_FS) {
        Status = STATUS_INVALID_PARAMETER;
        goto end;
    }

    Status = STATUS_NOT_IMPLEMENTED;

    if (Vcb->readonly) {
        Status = STATUS_MEDIA_WRITE_PROTECTED;
        goto end;
    }

    if (Vcb->removing || Vcb->locked) {
        Status = STATUS_ACCESS_DENIED;
        goto end;
    }

    switch (IrpSp->Parameters.SetVolume.FsInformationClass) {
        case FileFsControlInformation:
            FIXME("STUB: FileFsControlInformation\n");
            break;

        case FileFsLabelInformation:
            TRACE("FileFsLabelInformation\n");

            Status = set_label(Vcb, Irp->AssociatedIrp.SystemBuffer);
            break;

        case FileFsObjectIdInformation:
            FIXME("STUB: FileFsObjectIdInformation\n");
            break;

        default:
            WARN("Unrecognized FsInformationClass 0x%x\n", IrpSp->Parameters.SetVolume.FsInformationClass);
            break;
    }

end:
    Irp->IoStatus.Status = Status;
    Irp->IoStatus.Information = 0;

    TRACE("returning %08x\n", Status);

    IoCompleteRequest( Irp, IO_NO_INCREMENT );

    if (top_level)
        IoSetTopLevelIrp(NULL);

    FsRtlExitFileSystem();

    return Status;
}

void send_notification_fileref(_In_ file_ref* fileref, _In_ ULONG filter_match, _In_ ULONG action, _In_opt_ PUNICODE_STRING stream) {
    UNICODE_STRING fn;
    NTSTATUS Status;
    ULONG reqlen;
    USHORT name_offset;
    fcb* fcb = fileref->fcb;

    fn.Length = fn.MaximumLength = 0;
    Status = fileref_get_filename(fileref, &fn, NULL, &reqlen);
    if (Status != STATUS_BUFFER_OVERFLOW) {
        ERR("fileref_get_filename returned %08x\n", Status);
        return;
    }

    if (reqlen > 0xffff) {
        WARN("reqlen was too long for FsRtlNotifyFilterReportChange\n");
        return;
    }

    fn.Buffer = ExAllocatePoolWithTag(PagedPool, reqlen, ALLOC_TAG);
    if (!fn.Buffer) {
        ERR("out of memory\n");
        return;
    }

    fn.MaximumLength = (USHORT)reqlen;
    fn.Length = 0;

    Status = fileref_get_filename(fileref, &fn, &name_offset, &reqlen);
    if (!NT_SUCCESS(Status)) {
        ERR("fileref_get_filename returned %08x\n", Status);
        ExFreePool(fn.Buffer);
        return;
    }

    FsRtlNotifyFilterReportChange(fcb->Vcb->NotifySync, &fcb->Vcb->DirNotifyList, (PSTRING)&fn, name_offset,
                                  (PSTRING)stream, NULL, filter_match, action, NULL, NULL);
    ExFreePool(fn.Buffer);
}

static void send_notification_fcb(_In_ file_ref* fileref, _In_ ULONG filter_match, _In_ ULONG action, _In_opt_ PUNICODE_STRING stream) {
    fcb* fcb = fileref->fcb;
    LIST_ENTRY* le;
    NTSTATUS Status;

    // no point looking for hardlinks if st_nlink == 1
    if (fileref->fcb->inode_item.st_nlink == 1) {
        send_notification_fileref(fileref, filter_match, action, stream);
        return;
    }

    ExAcquireResourceExclusiveLite(&fcb->Vcb->fileref_lock, true);

    le = fcb->hardlinks.Flink;
    while (le != &fcb->hardlinks) {
        hardlink* hl = CONTAINING_RECORD(le, hardlink, list_entry);
        file_ref* parfr;

        Status = open_fileref_by_inode(fcb->Vcb, fcb->subvol, hl->parent, &parfr, NULL);

        if (!NT_SUCCESS(Status))
            ERR("open_fileref_by_inode returned %08x\n", Status);
        else if (!parfr->deleted) {
            UNICODE_STRING fn;
            ULONG pathlen;

            fn.Length = fn.MaximumLength = 0;
            Status = fileref_get_filename(parfr, &fn, NULL, &pathlen);
            if (Status != STATUS_BUFFER_OVERFLOW) {
                ERR("fileref_get_filename returned %08x\n", Status);
                free_fileref(parfr);
                break;
            }

            if (parfr != fcb->Vcb->root_fileref)
                pathlen += sizeof(WCHAR);

            if (pathlen + hl->name.Length > 0xffff) {
                WARN("pathlen + hl->name.Length was too long for FsRtlNotifyFilterReportChange\n");
                free_fileref(parfr);
                break;
            }

            fn.MaximumLength = (USHORT)(pathlen + hl->name.Length);
            fn.Buffer = ExAllocatePoolWithTag(PagedPool, fn.MaximumLength, ALLOC_TAG);
            if (!fn.Buffer) {
                ERR("out of memory\n");
                free_fileref(parfr);
                break;
            }

            Status = fileref_get_filename(parfr, &fn, NULL, NULL);
            if (!NT_SUCCESS(Status)) {
                ERR("fileref_get_filename returned %08x\n", Status);
                free_fileref(parfr);
                ExFreePool(fn.Buffer);
                break;
            }

            if (parfr != fcb->Vcb->root_fileref) {
                fn.Buffer[(pathlen / sizeof(WCHAR)) - 1] = '\\';
                fn.Length += sizeof(WCHAR);
            }

            RtlCopyMemory(&fn.Buffer[pathlen / sizeof(WCHAR)], hl->name.Buffer, hl->name.Length);
            fn.Length += hl->name.Length;

            FsRtlNotifyFilterReportChange(fcb->Vcb->NotifySync, &fcb->Vcb->DirNotifyList, (PSTRING)&fn, (USHORT)pathlen,
                                          (PSTRING)stream, NULL, filter_match, action, NULL, NULL);

            ExFreePool(fn.Buffer);

            free_fileref(parfr);
        }

        le = le->Flink;
    }

    ExReleaseResourceLite(&fcb->Vcb->fileref_lock);
}

typedef struct {
    file_ref* fileref;
    ULONG filter_match;
    ULONG action;
    PUNICODE_STRING stream;
    PIO_WORKITEM work_item;
} notification_fcb;

_Function_class_(IO_WORKITEM_ROUTINE)
static void __stdcall notification_work_item(PDEVICE_OBJECT DeviceObject, PVOID con) {
    notification_fcb* nf = con;

    UNUSED(DeviceObject);

    ExAcquireResourceSharedLite(&nf->fileref->fcb->Vcb->tree_lock, TRUE); // protect us from fileref being reaped

    send_notification_fcb(nf->fileref, nf->filter_match, nf->action, nf->stream);

    free_fileref(nf->fileref);

    ExReleaseResourceLite(&nf->fileref->fcb->Vcb->tree_lock);

    IoFreeWorkItem(nf->work_item);

    ExFreePool(nf);
}

void queue_notification_fcb(_In_ file_ref* fileref, _In_ ULONG filter_match, _In_ ULONG action, _In_opt_ PUNICODE_STRING stream) {
    notification_fcb* nf;
    PIO_WORKITEM work_item;

    nf = ExAllocatePoolWithTag(PagedPool, sizeof(notification_fcb), ALLOC_TAG);
    if (!nf) {
        ERR("out of memory\n");
        return;
    }

    work_item = IoAllocateWorkItem(master_devobj);
    if (!work_item) {
        ERR("out of memory\n");
        ExFreePool(nf);
        return;
    }

    InterlockedIncrement(&fileref->refcount);

    nf->fileref = fileref;
    nf->filter_match = filter_match;
    nf->action = action;
    nf->stream = stream;
    nf->work_item = work_item;

    IoQueueWorkItem(work_item, notification_work_item, DelayedWorkQueue, nf);
}

void mark_fcb_dirty(_In_ fcb* fcb) {
    if (!fcb->dirty) {
#ifdef DEBUG_FCB_REFCOUNTS
        LONG rc;
#endif
        fcb->dirty = true;

#ifdef DEBUG_FCB_REFCOUNTS
        rc = InterlockedIncrement(&fcb->refcount);
        WARN("fcb %p: refcount now %i\n", fcb, rc);
#else
        InterlockedIncrement(&fcb->refcount);
#endif

        ExAcquireResourceExclusiveLite(&fcb->Vcb->dirty_fcbs_lock, true);
        InsertTailList(&fcb->Vcb->dirty_fcbs, &fcb->list_entry_dirty);
        ExReleaseResourceLite(&fcb->Vcb->dirty_fcbs_lock);
    }

    fcb->Vcb->need_write = true;
}

void mark_fileref_dirty(_In_ file_ref* fileref) {
    if (!fileref->dirty) {
        fileref->dirty = true;
        increase_fileref_refcount(fileref);

        ExAcquireResourceExclusiveLite(&fileref->fcb->Vcb->dirty_filerefs_lock, true);
        InsertTailList(&fileref->fcb->Vcb->dirty_filerefs, &fileref->list_entry_dirty);
        ExReleaseResourceLite(&fileref->fcb->Vcb->dirty_filerefs_lock);
    }

    fileref->fcb->Vcb->need_write = true;
}

#ifdef DEBUG_FCB_REFCOUNTS
void _free_fcb(_Inout_ fcb* fcb, _In_ const char* func) {
    LONG rc = InterlockedDecrement(&fcb->refcount);
#else
void free_fcb(_Inout_ fcb* fcb) {
    InterlockedDecrement(&fcb->refcount);
#endif

#ifdef DEBUG_FCB_REFCOUNTS
    ERR("fcb %p (%s): refcount now %i (subvol %I64x, inode %I64x)\n", fcb, func, rc, fcb->subvol ? fcb->subvol->id : 0, fcb->inode);
#endif
}

void reap_fcb(fcb* fcb) {
    uint8_t c = fcb->hash >> 24;

    if (fcb->subvol && fcb->subvol->fcbs_ptrs[c] == &fcb->list_entry) {
        if (fcb->list_entry.Flink != &fcb->subvol->fcbs && (CONTAINING_RECORD(fcb->list_entry.Flink, struct _fcb, list_entry)->hash >> 24) == c)
            fcb->subvol->fcbs_ptrs[c] = fcb->list_entry.Flink;
        else
            fcb->subvol->fcbs_ptrs[c] = NULL;
    }

    if (fcb->list_entry.Flink)
        RemoveEntryList(&fcb->list_entry);

    if (fcb->list_entry_all.Flink)
        RemoveEntryList(&fcb->list_entry_all);

    ExDeleteResourceLite(&fcb->nonpaged->resource);
    ExDeleteResourceLite(&fcb->nonpaged->paging_resource);
    ExDeleteResourceLite(&fcb->nonpaged->dir_children_lock);

    ExFreeToNPagedLookasideList(&fcb->Vcb->fcb_np_lookaside, fcb->nonpaged);

    if (fcb->sd)
        ExFreePool(fcb->sd);

    if (fcb->adsxattr.Buffer)
        ExFreePool(fcb->adsxattr.Buffer);

    if (fcb->reparse_xattr.Buffer)
        ExFreePool(fcb->reparse_xattr.Buffer);

    if (fcb->ea_xattr.Buffer)
        ExFreePool(fcb->ea_xattr.Buffer);

    if (fcb->adsdata.Buffer)
        ExFreePool(fcb->adsdata.Buffer);

    while (!IsListEmpty(&fcb->extents)) {
        LIST_ENTRY* le = RemoveHeadList(&fcb->extents);
        extent* ext = CONTAINING_RECORD(le, extent, list_entry);

        if (ext->csum)
            ExFreePool(ext->csum);

        ExFreePool(ext);
    }

    while (!IsListEmpty(&fcb->hardlinks)) {
        LIST_ENTRY* le = RemoveHeadList(&fcb->hardlinks);
        hardlink* hl = CONTAINING_RECORD(le, hardlink, list_entry);

        if (hl->name.Buffer)
            ExFreePool(hl->name.Buffer);

        if (hl->utf8.Buffer)
            ExFreePool(hl->utf8.Buffer);

        ExFreePool(hl);
    }

    while (!IsListEmpty(&fcb->xattrs)) {
        xattr* xa = CONTAINING_RECORD(RemoveHeadList(&fcb->xattrs), xattr, list_entry);

        ExFreePool(xa);
    }

    while (!IsListEmpty(&fcb->dir_children_index)) {
        LIST_ENTRY* le = RemoveHeadList(&fcb->dir_children_index);
        dir_child* dc = CONTAINING_RECORD(le, dir_child, list_entry_index);

        ExFreePool(dc->utf8.Buffer);
        ExFreePool(dc->name.Buffer);
        ExFreePool(dc->name_uc.Buffer);
        ExFreePool(dc);
    }

    if (fcb->hash_ptrs)
        ExFreePool(fcb->hash_ptrs);

    if (fcb->hash_ptrs_uc)
        ExFreePool(fcb->hash_ptrs_uc);

    FsRtlUninitializeFileLock(&fcb->lock);
    FsRtlUninitializeOplock(fcb_oplock(fcb));

    if (fcb->pool_type == NonPagedPool)
        ExFreePool(fcb);
    else
        ExFreeToPagedLookasideList(&fcb->Vcb->fcb_lookaside, fcb);
}

void reap_fcbs(device_extension* Vcb) {
    LIST_ENTRY* le;

    le = Vcb->all_fcbs.Flink;
    while (le != &Vcb->all_fcbs) {
        fcb* fcb = CONTAINING_RECORD(le, struct _fcb, list_entry_all);
        LIST_ENTRY* le2 = le->Flink;

        if (fcb->refcount == 0)
            reap_fcb(fcb);

        le = le2;
    }
}

void free_fileref(_Inout_ file_ref* fr) {
    LONG rc;

    rc = InterlockedDecrement(&fr->refcount);
#ifdef __REACTOS__
    (void)rc;
#endif

#ifdef DEBUG_FCB_REFCOUNTS
    ERR("fileref %p: refcount now %i\n", fr, rc);
#endif

#ifdef _DEBUG
    if (rc < 0) {
        ERR("fileref %p: refcount now %i\n", fr, rc);
        int3;
    }
#endif
}

void reap_fileref(device_extension* Vcb, file_ref* fr) {
    // FIXME - do we need a file_ref lock?

    // FIXME - do delete if needed

    ExDeleteResourceLite(&fr->nonpaged->fileref_lock);

    ExFreeToNPagedLookasideList(&Vcb->fileref_np_lookaside, fr->nonpaged);

    // FIXME - throw error if children not empty

    if (fr->fcb->fileref == fr)
        fr->fcb->fileref = NULL;

    if (fr->dc) {
        if (fr->fcb->ads)
            fr->dc->size = fr->fcb->adsdata.Length;

        fr->dc->fileref = NULL;
    }

    if (fr->list_entry.Flink)
        RemoveEntryList(&fr->list_entry);

    if (fr->parent)
        free_fileref(fr->parent);

    free_fcb(fr->fcb);

    if (fr->oldutf8.Buffer)
        ExFreePool(fr->oldutf8.Buffer);

    ExFreeToPagedLookasideList(&Vcb->fileref_lookaside, fr);
}

void reap_filerefs(device_extension* Vcb, file_ref* fr) {
    LIST_ENTRY* le;

    // FIXME - recursion is a bad idea in kernel mode

    le = fr->children.Flink;
    while (le != &fr->children) {
        file_ref* c = CONTAINING_RECORD(le, file_ref, list_entry);
        LIST_ENTRY* le2 = le->Flink;

        reap_filerefs(Vcb, c);

        le = le2;
    }

    if (fr->refcount == 0)
        reap_fileref(Vcb, fr);
}

static NTSTATUS close_file(_In_ PFILE_OBJECT FileObject, _In_ PIRP Irp) {
    fcb* fcb;
    ccb* ccb;
    file_ref* fileref = NULL;
    LONG open_files;

    UNUSED(Irp);

    TRACE("FileObject = %p\n", FileObject);

    fcb = FileObject->FsContext;
    if (!fcb) {
        TRACE("FCB was NULL, returning success\n");
        return STATUS_SUCCESS;
    }

    open_files = InterlockedDecrement(&fcb->Vcb->open_files);

    ccb = FileObject->FsContext2;

    TRACE("close called for fcb %p)\n", fcb);

    // FIXME - make sure notification gets sent if file is being deleted

    if (ccb) {
        if (ccb->query_string.Buffer)
            RtlFreeUnicodeString(&ccb->query_string);

        if (ccb->filename.Buffer)
            ExFreePool(ccb->filename.Buffer);

        // FIXME - use refcounts for fileref
        fileref = ccb->fileref;

        if (fcb->Vcb->running_sends > 0) {
            bool send_cancelled = false;

            ExAcquireResourceExclusiveLite(&fcb->Vcb->send_load_lock, true);

            if (ccb->send) {
                ccb->send->cancelling = true;
                send_cancelled = true;
                KeSetEvent(&ccb->send->cleared_event, 0, false);
            }

            ExReleaseResourceLite(&fcb->Vcb->send_load_lock);

            if (send_cancelled) {
                while (ccb->send) {
                    ExAcquireResourceExclusiveLite(&fcb->Vcb->send_load_lock, true);
                    ExReleaseResourceLite(&fcb->Vcb->send_load_lock);
                }
            }
        }

        ExFreePool(ccb);
    }

    CcUninitializeCacheMap(FileObject, NULL, NULL);

    if (open_files == 0 && fcb->Vcb->removing) {
        uninit(fcb->Vcb);
        return STATUS_SUCCESS;
    }

    if (!(fcb->Vcb->Vpb->Flags & VPB_MOUNTED))
        return STATUS_SUCCESS;

    if (fileref)
        free_fileref(fileref);
    else
        free_fcb(fcb);

    return STATUS_SUCCESS;
}

void uninit(_In_ device_extension* Vcb) {
    uint64_t i;
    KIRQL irql;
    NTSTATUS Status;
    LIST_ENTRY* le;
    LARGE_INTEGER time;

    if (!Vcb->removing) {
        ExAcquireResourceExclusiveLite(&Vcb->tree_lock, true);
        Vcb->removing = true;
        ExReleaseResourceLite(&Vcb->tree_lock);
    }

    if (Vcb->vde && Vcb->vde->mounted_device == Vcb->devobj)
        Vcb->vde->mounted_device = NULL;

    IoAcquireVpbSpinLock(&irql);
    Vcb->Vpb->Flags &= ~VPB_MOUNTED;
    Vcb->Vpb->Flags |= VPB_DIRECT_WRITES_ALLOWED;
    Vcb->Vpb->DeviceObject = NULL;
    IoReleaseVpbSpinLock(irql);

    RemoveEntryList(&Vcb->list_entry);

    if (Vcb->balance.thread) {
        Vcb->balance.paused = false;
        Vcb->balance.stopping = true;
        KeSetEvent(&Vcb->balance.event, 0, false);
        KeWaitForSingleObject(&Vcb->balance.finished, Executive, KernelMode, false, NULL);
    }

    if (Vcb->scrub.thread) {
        Vcb->scrub.paused = false;
        Vcb->scrub.stopping = true;
        KeSetEvent(&Vcb->scrub.event, 0, false);
        KeWaitForSingleObject(&Vcb->scrub.finished, Executive, KernelMode, false, NULL);
    }

    if (Vcb->running_sends != 0) {
        bool send_cancelled = false;

        ExAcquireResourceExclusiveLite(&Vcb->send_load_lock, true);

        le = Vcb->send_ops.Flink;
        while (le != &Vcb->send_ops) {
            send_info* send = CONTAINING_RECORD(le, send_info, list_entry);

            if (!send->cancelling) {
                send->cancelling = true;
                send_cancelled = true;
                send->ccb = NULL;
                KeSetEvent(&send->cleared_event, 0, false);
            }

            le = le->Flink;
        }

        ExReleaseResourceLite(&Vcb->send_load_lock);

        if (send_cancelled) {
            while (Vcb->running_sends != 0) {
                ExAcquireResourceExclusiveLite(&Vcb->send_load_lock, true);
                ExReleaseResourceLite(&Vcb->send_load_lock);
            }
        }
    }

    Status = registry_mark_volume_unmounted(&Vcb->superblock.uuid);
    if (!NT_SUCCESS(Status) && Status != STATUS_TOO_LATE)
        WARN("registry_mark_volume_unmounted returned %08x\n", Status);

    for (i = 0; i < Vcb->calcthreads.num_threads; i++) {
        Vcb->calcthreads.threads[i].quit = true;
    }

    KeSetEvent(&Vcb->calcthreads.event, 0, false);

    for (i = 0; i < Vcb->calcthreads.num_threads; i++) {
        KeWaitForSingleObject(&Vcb->calcthreads.threads[i].finished, Executive, KernelMode, false, NULL);

        ZwClose(Vcb->calcthreads.threads[i].handle);
    }

    ExDeleteResourceLite(&Vcb->calcthreads.lock);
    ExFreePool(Vcb->calcthreads.threads);

    time.QuadPart = 0;
    KeSetTimer(&Vcb->flush_thread_timer, time, NULL); // trigger the timer early
    KeWaitForSingleObject(&Vcb->flush_thread_finished, Executive, KernelMode, false, NULL);

    reap_fcb(Vcb->volume_fcb);
    reap_fcb(Vcb->dummy_fcb);

    if (Vcb->root_file)
        ObDereferenceObject(Vcb->root_file);

    le = Vcb->chunks.Flink;
    while (le != &Vcb->chunks) {
        chunk* c = CONTAINING_RECORD(le, chunk, list_entry);

        if (c->cache) {
            reap_fcb(c->cache);
            c->cache = NULL;
        }

        le = le->Flink;
    }

    while (!IsListEmpty(&Vcb->all_fcbs)) {
        fcb* fcb = CONTAINING_RECORD(Vcb->all_fcbs.Flink, struct _fcb, list_entry_all);

        reap_fcb(fcb);
    }

    while (!IsListEmpty(&Vcb->sys_chunks)) {
        sys_chunk* sc = CONTAINING_RECORD(RemoveHeadList(&Vcb->sys_chunks), sys_chunk, list_entry);

        if (sc->data)
            ExFreePool(sc->data);

        ExFreePool(sc);
    }

    while (!IsListEmpty(&Vcb->roots)) {
        root* r = CONTAINING_RECORD(RemoveHeadList(&Vcb->roots), root, list_entry);

        ExDeleteResourceLite(&r->nonpaged->load_tree_lock);
        ExFreePool(r->nonpaged);
        ExFreePool(r);
    }

    while (!IsListEmpty(&Vcb->chunks)) {
        chunk* c = CONTAINING_RECORD(RemoveHeadList(&Vcb->chunks), chunk, list_entry);

        while (!IsListEmpty(&c->space)) {
            LIST_ENTRY* le2 = RemoveHeadList(&c->space);
            space* s = CONTAINING_RECORD(le2, space, list_entry);

            ExFreePool(s);
        }

        while (!IsListEmpty(&c->deleting)) {
            LIST_ENTRY* le2 = RemoveHeadList(&c->deleting);
            space* s = CONTAINING_RECORD(le2, space, list_entry);

            ExFreePool(s);
        }

        if (c->devices)
            ExFreePool(c->devices);

        if (c->cache)
            reap_fcb(c->cache);

        ExDeleteResourceLite(&c->range_locks_lock);
        ExDeleteResourceLite(&c->partial_stripes_lock);
        ExDeleteResourceLite(&c->lock);
        ExDeleteResourceLite(&c->changed_extents_lock);

        ExFreePool(c->chunk_item);
        ExFreePool(c);
    }

    while (!IsListEmpty(&Vcb->devices)) {
        device* dev = CONTAINING_RECORD(RemoveHeadList(&Vcb->devices), device, list_entry);

        while (!IsListEmpty(&dev->space)) {
            LIST_ENTRY* le2 = RemoveHeadList(&dev->space);
            space* s = CONTAINING_RECORD(le2, space, list_entry);

            ExFreePool(s);
        }

        ExFreePool(dev);
    }

    ExAcquireResourceExclusiveLite(&Vcb->scrub.stats_lock, true);
    while (!IsListEmpty(&Vcb->scrub.errors)) {
        scrub_error* err = CONTAINING_RECORD(RemoveHeadList(&Vcb->scrub.errors), scrub_error, list_entry);

        ExFreePool(err);
    }
    ExReleaseResourceLite(&Vcb->scrub.stats_lock);

    ExDeleteResourceLite(&Vcb->fcb_lock);
    ExDeleteResourceLite(&Vcb->fileref_lock);
    ExDeleteResourceLite(&Vcb->load_lock);
    ExDeleteResourceLite(&Vcb->tree_lock);
    ExDeleteResourceLite(&Vcb->chunk_lock);
    ExDeleteResourceLite(&Vcb->dirty_fcbs_lock);
    ExDeleteResourceLite(&Vcb->dirty_filerefs_lock);
    ExDeleteResourceLite(&Vcb->dirty_subvols_lock);
    ExDeleteResourceLite(&Vcb->scrub.stats_lock);
    ExDeleteResourceLite(&Vcb->send_load_lock);

    ExDeletePagedLookasideList(&Vcb->tree_data_lookaside);
    ExDeletePagedLookasideList(&Vcb->traverse_ptr_lookaside);
    ExDeletePagedLookasideList(&Vcb->batch_item_lookaside);
    ExDeletePagedLookasideList(&Vcb->fileref_lookaside);
    ExDeletePagedLookasideList(&Vcb->fcb_lookaside);
    ExDeletePagedLookasideList(&Vcb->name_bit_lookaside);
    ExDeleteNPagedLookasideList(&Vcb->range_lock_lookaside);
    ExDeleteNPagedLookasideList(&Vcb->fileref_np_lookaside);
    ExDeleteNPagedLookasideList(&Vcb->fcb_np_lookaside);

    ZwClose(Vcb->flush_thread_handle);

    if (Vcb->devobj->AttachedDevice)
        IoDetachDevice(Vcb->devobj);

    IoDeleteDevice(Vcb->devobj);
}

static NTSTATUS delete_fileref_fcb(_In_ file_ref* fileref, _In_opt_ PFILE_OBJECT FileObject, _In_opt_ PIRP Irp, _In_ LIST_ENTRY* rollback) {
    NTSTATUS Status;
    LIST_ENTRY* le;

    // excise extents

    if (fileref->fcb->type != BTRFS_TYPE_DIRECTORY && fileref->fcb->inode_item.st_size > 0) {
        Status = excise_extents(fileref->fcb->Vcb, fileref->fcb, 0, sector_align(fileref->fcb->inode_item.st_size, fileref->fcb->Vcb->superblock.sector_size), Irp, rollback);
        if (!NT_SUCCESS(Status)) {
            ERR("excise_extents returned %08x\n", Status);
            return Status;
        }
    }

    fileref->fcb->Header.AllocationSize.QuadPart = 0;
    fileref->fcb->Header.FileSize.QuadPart = 0;
    fileref->fcb->Header.ValidDataLength.QuadPart = 0;

    if (FileObject) {
        CC_FILE_SIZES ccfs;

        ccfs.AllocationSize = fileref->fcb->Header.AllocationSize;
        ccfs.FileSize = fileref->fcb->Header.FileSize;
        ccfs.ValidDataLength = fileref->fcb->Header.ValidDataLength;

        Status = STATUS_SUCCESS;

        _SEH2_TRY {
            CcSetFileSizes(FileObject, &ccfs);
        } _SEH2_EXCEPT (EXCEPTION_EXECUTE_HANDLER) {
            Status = _SEH2_GetExceptionCode();
        } _SEH2_END;

        if (!NT_SUCCESS(Status)) {
            ERR("CcSetFileSizes threw exception %08x\n", Status);
            return Status;
        }
    }

    fileref->fcb->deleted = true;

    le = fileref->children.Flink;
    while (le != &fileref->children) {
        file_ref* fr2 = CONTAINING_RECORD(le, file_ref, list_entry);

        if (fr2->fcb->ads) {
            fr2->fcb->deleted = true;
            mark_fcb_dirty(fr2->fcb);
        }

        le = le->Flink;
    }

    return STATUS_SUCCESS;
}

NTSTATUS delete_fileref(_In_ file_ref* fileref, _In_opt_ PFILE_OBJECT FileObject, _In_ bool make_orphan, _In_opt_ PIRP Irp, _In_ LIST_ENTRY* rollback) {
    LARGE_INTEGER newlength, time;
    BTRFS_TIME now;
    NTSTATUS Status;
    ULONG utf8len = 0;

    KeQuerySystemTime(&time);
    win_time_to_unix(time, &now);

    ExAcquireResourceExclusiveLite(fileref->fcb->Header.Resource, true);

    if (fileref->deleted) {
        ExReleaseResourceLite(fileref->fcb->Header.Resource);
        return STATUS_SUCCESS;
    }

    if (fileref->fcb->subvol->send_ops > 0) {
        ExReleaseResourceLite(fileref->fcb->Header.Resource);
        return STATUS_ACCESS_DENIED;
    }

    fileref->deleted = true;
    mark_fileref_dirty(fileref);

    // delete INODE_ITEM (0x1)

    TRACE("nlink = %u\n", fileref->fcb->inode_item.st_nlink);

    if (!fileref->fcb->ads) {
        if (fileref->parent->fcb->subvol == fileref->fcb->subvol) {
            LIST_ENTRY* le;

            mark_fcb_dirty(fileref->fcb);

            fileref->fcb->inode_item_changed = true;

            if (fileref->fcb->inode_item.st_nlink > 1 || make_orphan) {
                fileref->fcb->inode_item.st_nlink--;
                fileref->fcb->inode_item.transid = fileref->fcb->Vcb->superblock.generation;
                fileref->fcb->inode_item.sequence++;
                fileref->fcb->inode_item.st_ctime = now;
            } else {
                Status = delete_fileref_fcb(fileref, FileObject, Irp, rollback);
                if (!NT_SUCCESS(Status)) {
                    ERR("delete_fileref_fcb returned %08x\n", Status);
                    ExReleaseResourceLite(fileref->fcb->Header.Resource);
                    return Status;
                }
            }

            if (fileref->dc) {
                le = fileref->fcb->hardlinks.Flink;
                while (le != &fileref->fcb->hardlinks) {
                    hardlink* hl = CONTAINING_RECORD(le, hardlink, list_entry);

                    if (hl->parent == fileref->parent->fcb->inode && hl->index == fileref->dc->index) {
                        RemoveEntryList(&hl->list_entry);

                        if (hl->name.Buffer)
                            ExFreePool(hl->name.Buffer);

                        if (hl->utf8.Buffer)
                            ExFreePool(hl->utf8.Buffer);

                        ExFreePool(hl);
                        break;
                    }

                    le = le->Flink;
                }
            }
        } else if (fileref->fcb->subvol->parent == fileref->parent->fcb->subvol->id) { // valid subvolume
            if (fileref->fcb->subvol->root_item.num_references > 1) {
                fileref->fcb->subvol->root_item.num_references--;

                mark_fcb_dirty(fileref->fcb); // so ROOT_ITEM gets updated
            } else {
                LIST_ENTRY* le;

                // FIXME - we need a lock here

                RemoveEntryList(&fileref->fcb->subvol->list_entry);

                InsertTailList(&fileref->fcb->Vcb->drop_roots, &fileref->fcb->subvol->list_entry);

                le = fileref->children.Flink;
                while (le != &fileref->children) {
                    file_ref* fr2 = CONTAINING_RECORD(le, file_ref, list_entry);

                    if (fr2->fcb->ads) {
                        fr2->fcb->deleted = true;
                        mark_fcb_dirty(fr2->fcb);
                    }

                    le = le->Flink;
                }
            }
        }
    } else {
        fileref->fcb->deleted = true;
        mark_fcb_dirty(fileref->fcb);
    }

    // remove dir_child from parent

    if (fileref->dc) {
        TRACE("delete file %.*S\n", fileref->dc->name.Length / sizeof(WCHAR), fileref->dc->name.Buffer);

        ExAcquireResourceExclusiveLite(&fileref->parent->fcb->nonpaged->dir_children_lock, true);
        RemoveEntryList(&fileref->dc->list_entry_index);

        if (!fileref->fcb->ads)
            remove_dir_child_from_hash_lists(fileref->parent->fcb, fileref->dc);

        ExReleaseResourceLite(&fileref->parent->fcb->nonpaged->dir_children_lock);

        if (!fileref->oldutf8.Buffer)
            fileref->oldutf8 = fileref->dc->utf8;
        else
            ExFreePool(fileref->dc->utf8.Buffer);

        utf8len = fileref->dc->utf8.Length;

        fileref->oldindex = fileref->dc->index;

        ExFreePool(fileref->dc->name.Buffer);
        ExFreePool(fileref->dc->name_uc.Buffer);
        ExFreePool(fileref->dc);

        fileref->dc = NULL;
    }

    // update INODE_ITEM of parent

    ExAcquireResourceExclusiveLite(fileref->parent->fcb->Header.Resource, true);

    fileref->parent->fcb->inode_item.transid = fileref->fcb->Vcb->superblock.generation;
    fileref->parent->fcb->inode_item.sequence++;
    fileref->parent->fcb->inode_item.st_ctime = now;

    if (!fileref->fcb->ads) {
        TRACE("fileref->parent->fcb->inode_item.st_size (inode %I64x) was %I64x\n", fileref->parent->fcb->inode, fileref->parent->fcb->inode_item.st_size);
        fileref->parent->fcb->inode_item.st_size -= utf8len * 2;
        TRACE("fileref->parent->fcb->inode_item.st_size (inode %I64x) now %I64x\n", fileref->parent->fcb->inode, fileref->parent->fcb->inode_item.st_size);
        fileref->parent->fcb->inode_item.st_mtime = now;
    }

    fileref->parent->fcb->inode_item_changed = true;
    ExReleaseResourceLite(fileref->parent->fcb->Header.Resource);

    if (!fileref->fcb->ads && fileref->parent->dc)
        send_notification_fcb(fileref->parent, FILE_NOTIFY_CHANGE_LAST_WRITE, FILE_ACTION_MODIFIED, NULL);

    mark_fcb_dirty(fileref->parent->fcb);

    fileref->fcb->subvol->root_item.ctransid = fileref->fcb->Vcb->superblock.generation;
    fileref->fcb->subvol->root_item.ctime = now;

    newlength.QuadPart = 0;

    if (FileObject && !CcUninitializeCacheMap(FileObject, &newlength, NULL))
        TRACE("CcUninitializeCacheMap failed\n");

    ExReleaseResourceLite(fileref->fcb->Header.Resource);

    return STATUS_SUCCESS;
}

_Dispatch_type_(IRP_MJ_CLEANUP)
_Function_class_(DRIVER_DISPATCH)
static NTSTATUS __stdcall drv_cleanup(_In_ PDEVICE_OBJECT DeviceObject, _In_ PIRP Irp) {
    NTSTATUS Status;
    PIO_STACK_LOCATION IrpSp = IoGetCurrentIrpStackLocation(Irp);
    PFILE_OBJECT FileObject = IrpSp->FileObject;
    device_extension* Vcb = DeviceObject->DeviceExtension;
    fcb* fcb = FileObject->FsContext;
    bool top_level;

    FsRtlEnterFileSystem();

    TRACE("cleanup\n");

    top_level = is_top_level(Irp);

    if (Vcb && Vcb->type == VCB_TYPE_VOLUME) {
        Status = vol_cleanup(DeviceObject, Irp);
        goto exit;
    } else if (DeviceObject == master_devobj) {
        TRACE("closing file system\n");
        Status = STATUS_SUCCESS;
        goto exit;
    } else if (!Vcb || Vcb->type != VCB_TYPE_FS) {
        Status = STATUS_INVALID_PARAMETER;
        goto exit;
    }

    if (FileObject->Flags & FO_CLEANUP_COMPLETE) {
        TRACE("FileObject %p already cleaned up\n", FileObject);
        Status = STATUS_SUCCESS;
        goto exit;
    }

    if (!fcb) {
        ERR("fcb was NULL\n");
        Status = STATUS_INVALID_PARAMETER;
        goto exit;
    }

    FsRtlCheckOplock(fcb_oplock(fcb), Irp, NULL, NULL, NULL);

    // We have to use the pointer to Vcb stored in the fcb, as we can receive cleanup
    // messages belonging to other devices.

    if (FileObject && FileObject->FsContext) {
        LONG oc;
        ccb* ccb;
        file_ref* fileref;
        bool locked = true;

        ccb = FileObject->FsContext2;
        fileref = ccb ? ccb->fileref : NULL;

        TRACE("cleanup called for FileObject %p\n", FileObject);
        TRACE("fileref %p, refcount = %u, open_count = %u\n", fileref, fileref ? fileref->refcount : 0, fileref ? fileref->open_count : 0);

        ExAcquireResourceSharedLite(&fcb->Vcb->tree_lock, true);

        ExAcquireResourceExclusiveLite(fcb->Header.Resource, true);

        IoRemoveShareAccess(FileObject, &fcb->share_access);

        FsRtlFastUnlockAll(&fcb->lock, FileObject, IoGetRequestorProcess(Irp), NULL);

        if (ccb)
            FsRtlNotifyCleanup(fcb->Vcb->NotifySync, &fcb->Vcb->DirNotifyList, ccb);

        if (fileref) {
            oc = InterlockedDecrement(&fileref->open_count);
#ifdef DEBUG_FCB_REFCOUNTS
            ERR("fileref %p: open_count now %i\n", fileref, oc);
#endif
        }

        if (ccb && ccb->options & FILE_DELETE_ON_CLOSE && fileref)
            fileref->delete_on_close = true;

        if (fileref && fileref->delete_on_close && fcb->type == BTRFS_TYPE_DIRECTORY && fcb->inode_item.st_size > 0 && fcb != fcb->Vcb->dummy_fcb)
            fileref->delete_on_close = false;

        if (fcb->Vcb->locked && fcb->Vcb->locked_fileobj == FileObject) {
            TRACE("unlocking volume\n");
            do_unlock_volume(fcb->Vcb);
            FsRtlNotifyVolumeEvent(FileObject, FSRTL_VOLUME_UNLOCK);
        }

        if (ccb && ccb->reserving) {
            fcb->subvol->reserved = NULL;
            ccb->reserving = false;
            // FIXME - flush all of subvol's fcbs
        }

        if (fileref && (oc == 0 || (fileref->delete_on_close && fileref->posix_delete))) {
            if (!fcb->Vcb->removing) {
                if (oc == 0 && fileref->fcb->inode_item.st_nlink == 0 && fileref != fcb->Vcb->root_fileref &&
                    fcb != fcb->Vcb->volume_fcb && !fcb->ads) { // last handle closed on POSIX-deleted file
                    LIST_ENTRY rollback;

                    InitializeListHead(&rollback);

                    Status = delete_fileref_fcb(fileref, FileObject, Irp, &rollback);
                    if (!NT_SUCCESS(Status)) {
                        ERR("delete_fileref_fcb returned %08x\n", Status);
                        do_rollback(fcb->Vcb, &rollback);
                        ExReleaseResourceLite(fileref->fcb->Header.Resource);
                        ExReleaseResourceLite(&fcb->Vcb->tree_lock);
                        goto exit;
                    }

                    clear_rollback(&rollback);

                    mark_fcb_dirty(fileref->fcb);
                } else if (fileref->delete_on_close && fileref != fcb->Vcb->root_fileref && fcb != fcb->Vcb->volume_fcb) {
                    LIST_ENTRY rollback;

                    InitializeListHead(&rollback);

                    if (!fileref->fcb->ads || fileref->dc) {
                        if (fileref->fcb->ads) {
                            send_notification_fileref(fileref->parent, fcb->type == BTRFS_TYPE_DIRECTORY ? FILE_NOTIFY_CHANGE_DIR_NAME : FILE_NOTIFY_CHANGE_FILE_NAME,
                                                      FILE_ACTION_REMOVED, &fileref->dc->name);
                        } else
                            send_notification_fileref(fileref, fcb->type == BTRFS_TYPE_DIRECTORY ? FILE_NOTIFY_CHANGE_DIR_NAME : FILE_NOTIFY_CHANGE_FILE_NAME, FILE_ACTION_REMOVED, NULL);
                    }

                    ExReleaseResourceLite(fcb->Header.Resource);
                    locked = false;

                    // fileref_lock needs to be acquired before fcb->Header.Resource
                    ExAcquireResourceExclusiveLite(&fcb->Vcb->fileref_lock, true);

                    Status = delete_fileref(fileref, FileObject, oc > 0 && fileref->posix_delete, Irp, &rollback);
                    if (!NT_SUCCESS(Status)) {
                        ERR("delete_fileref returned %08x\n", Status);
                        do_rollback(fcb->Vcb, &rollback);
                        ExReleaseResourceLite(&fcb->Vcb->fileref_lock);
                        ExReleaseResourceLite(&fcb->Vcb->tree_lock);
                        goto exit;
                    }

                    ExReleaseResourceLite(&fcb->Vcb->fileref_lock);

                    clear_rollback(&rollback);
                } else if (FileObject->Flags & FO_CACHE_SUPPORTED && FileObject->SectionObjectPointer->DataSectionObject) {
                    IO_STATUS_BLOCK iosb;
                    CcFlushCache(FileObject->SectionObjectPointer, NULL, 0, &iosb);

                    if (!NT_SUCCESS(iosb.Status)) {
                        ERR("CcFlushCache returned %08x\n", iosb.Status);
                    }

                    if (!ExIsResourceAcquiredSharedLite(fcb->Header.PagingIoResource)) {
                        ExAcquireResourceExclusiveLite(fcb->Header.PagingIoResource, true);
                        ExReleaseResourceLite(fcb->Header.PagingIoResource);
                    }

                    CcPurgeCacheSection(FileObject->SectionObjectPointer, NULL, 0, false);

                    TRACE("flushed cache on close (FileObject = %p, fcb = %p, AllocationSize = %I64x, FileSize = %I64x, ValidDataLength = %I64x)\n",
                        FileObject, fcb, fcb->Header.AllocationSize.QuadPart, fcb->Header.FileSize.QuadPart, fcb->Header.ValidDataLength.QuadPart);
                }
            }

            if (fcb->Vcb && fcb != fcb->Vcb->volume_fcb)
                CcUninitializeCacheMap(FileObject, NULL, NULL);
        }

        if (locked)
            ExReleaseResourceLite(fcb->Header.Resource);

        ExReleaseResourceLite(&fcb->Vcb->tree_lock);

        FileObject->Flags |= FO_CLEANUP_COMPLETE;
    }

    Status = STATUS_SUCCESS;

exit:
    TRACE("returning %08x\n", Status);

    Irp->IoStatus.Status = Status;
    Irp->IoStatus.Information = 0;

    IoCompleteRequest(Irp, IO_NO_INCREMENT);

    if (top_level)
        IoSetTopLevelIrp(NULL);

    FsRtlExitFileSystem();

    return Status;
}

_Success_(return)
bool get_file_attributes_from_xattr(_In_reads_bytes_(len) char* val, _In_ uint16_t len, _Out_ ULONG* atts) {
    if (len > 2 && val[0] == '0' && val[1] == 'x') {
        int i;
        ULONG dosnum = 0;

        for (i = 2; i < len; i++) {
            dosnum *= 0x10;

            if (val[i] >= '0' && val[i] <= '9')
                dosnum |= val[i] - '0';
            else if (val[i] >= 'a' && val[i] <= 'f')
                dosnum |= val[i] + 10 - 'a';
            else if (val[i] >= 'A' && val[i] <= 'F')
                dosnum |= val[i] + 10 - 'a';
        }

        TRACE("DOSATTRIB: %08x\n", dosnum);

        *atts = dosnum;

        return true;
    }

    return false;
}

ULONG get_file_attributes(_In_ _Requires_lock_held_(_Curr_->tree_lock) device_extension* Vcb, _In_ root* r, _In_ uint64_t inode,
                          _In_ uint8_t type, _In_ bool dotfile, _In_ bool ignore_xa, _In_opt_ PIRP Irp) {
    ULONG att;
    char* eaval;
    uint16_t ealen;

    if (!ignore_xa && get_xattr(Vcb, r, inode, EA_DOSATTRIB, EA_DOSATTRIB_HASH, (uint8_t**)&eaval, &ealen, Irp)) {
        ULONG dosnum = 0;

        if (get_file_attributes_from_xattr(eaval, ealen, &dosnum)) {
            ExFreePool(eaval);

            if (type == BTRFS_TYPE_DIRECTORY)
                dosnum |= FILE_ATTRIBUTE_DIRECTORY;
            else if (type == BTRFS_TYPE_SYMLINK)
                dosnum |= FILE_ATTRIBUTE_REPARSE_POINT;

            if (type != BTRFS_TYPE_DIRECTORY)
                dosnum &= ~FILE_ATTRIBUTE_DIRECTORY;

            if (inode == SUBVOL_ROOT_INODE) {
                if (r->root_item.flags & BTRFS_SUBVOL_READONLY)
                    dosnum |= FILE_ATTRIBUTE_READONLY;
                else
                    dosnum &= ~FILE_ATTRIBUTE_READONLY;
            }

            return dosnum;
        }

        ExFreePool(eaval);
    }

    switch (type) {
        case BTRFS_TYPE_DIRECTORY:
            att = FILE_ATTRIBUTE_DIRECTORY;
            break;

        case BTRFS_TYPE_SYMLINK:
            att = FILE_ATTRIBUTE_REPARSE_POINT;
            break;

        default:
            att = 0;
            break;
    }

    if (dotfile || (r->id == BTRFS_ROOT_FSTREE && inode == SUBVOL_ROOT_INODE))
        att |= FILE_ATTRIBUTE_HIDDEN;

    att |= FILE_ATTRIBUTE_ARCHIVE;

    if (inode == SUBVOL_ROOT_INODE) {
        if (r->root_item.flags & BTRFS_SUBVOL_READONLY)
            att |= FILE_ATTRIBUTE_READONLY;
        else
            att &= ~FILE_ATTRIBUTE_READONLY;
    }

    // FIXME - get READONLY from ii->st_mode
    // FIXME - return SYSTEM for block/char devices?

    if (att == 0)
        att = FILE_ATTRIBUTE_NORMAL;

    return att;
}

NTSTATUS sync_read_phys(_In_ PDEVICE_OBJECT DeviceObject, _In_ PFILE_OBJECT FileObject, _In_ uint64_t StartingOffset, _In_ ULONG Length,
                        _Out_writes_bytes_(Length) PUCHAR Buffer, _In_ bool override) {
    IO_STATUS_BLOCK IoStatus;
    LARGE_INTEGER Offset;
    PIRP Irp;
    PIO_STACK_LOCATION IrpSp;
    NTSTATUS Status;
    read_context context;

    num_reads++;

    RtlZeroMemory(&context, sizeof(read_context));
    KeInitializeEvent(&context.Event, NotificationEvent, false);

    Offset.QuadPart = (LONGLONG)StartingOffset;

    Irp = IoAllocateIrp(DeviceObject->StackSize, false);

    if (!Irp) {
        ERR("IoAllocateIrp failed\n");
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    Irp->Flags |= IRP_NOCACHE;
    IrpSp = IoGetNextIrpStackLocation(Irp);
    IrpSp->MajorFunction = IRP_MJ_READ;
    IrpSp->FileObject = FileObject;

    if (override)
        IrpSp->Flags |= SL_OVERRIDE_VERIFY_VOLUME;

    if (DeviceObject->Flags & DO_BUFFERED_IO) {
        Irp->AssociatedIrp.SystemBuffer = ExAllocatePoolWithTag(NonPagedPool, Length, ALLOC_TAG);
        if (!Irp->AssociatedIrp.SystemBuffer) {
            ERR("out of memory\n");
            Status = STATUS_INSUFFICIENT_RESOURCES;
            goto exit;
        }

        Irp->Flags |= IRP_BUFFERED_IO | IRP_DEALLOCATE_BUFFER | IRP_INPUT_OPERATION;

        Irp->UserBuffer = Buffer;
    } else if (DeviceObject->Flags & DO_DIRECT_IO) {
        Irp->MdlAddress = IoAllocateMdl(Buffer, Length, false, false, NULL);
        if (!Irp->MdlAddress) {
            ERR("IoAllocateMdl failed\n");
            Status = STATUS_INSUFFICIENT_RESOURCES;
            goto exit;
        }

        Status = STATUS_SUCCESS;

        _SEH2_TRY {
            MmProbeAndLockPages(Irp->MdlAddress, KernelMode, IoWriteAccess);
        } _SEH2_EXCEPT (EXCEPTION_EXECUTE_HANDLER) {
            Status = _SEH2_GetExceptionCode();
        } _SEH2_END;

        if (!NT_SUCCESS(Status)) {
            ERR("MmProbeAndLockPages threw exception %08x\n", Status);
            IoFreeMdl(Irp->MdlAddress);
            goto exit;
        }
    } else
        Irp->UserBuffer = Buffer;

    IrpSp->Parameters.Read.Length = Length;
    IrpSp->Parameters.Read.ByteOffset = Offset;

    Irp->UserIosb = &IoStatus;

    Irp->UserEvent = &context.Event;

    IoSetCompletionRoutine(Irp, read_completion, &context, true, true, true);

    Status = IoCallDriver(DeviceObject, Irp);

    if (Status == STATUS_PENDING) {
        KeWaitForSingleObject(&context.Event, Executive, KernelMode, false, NULL);
        Status = context.iosb.Status;
    }

    if (DeviceObject->Flags & DO_DIRECT_IO) {
        MmUnlockPages(Irp->MdlAddress);
        IoFreeMdl(Irp->MdlAddress);
    }

exit:
    IoFreeIrp(Irp);

    return Status;
}

static NTSTATUS read_superblock(_In_ device_extension* Vcb, _In_ PDEVICE_OBJECT device, _In_ PFILE_OBJECT fileobj, _In_ uint64_t length) {
    NTSTATUS Status;
    superblock* sb;
    ULONG i, to_read;
    uint8_t valid_superblocks;

    to_read = device->SectorSize == 0 ? sizeof(superblock) : (ULONG)sector_align(sizeof(superblock), device->SectorSize);

    sb = ExAllocatePoolWithTag(NonPagedPool, to_read, ALLOC_TAG);
    if (!sb) {
        ERR("out of memory\n");
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    if (superblock_addrs[0] + to_read > length) {
        WARN("device was too short to have any superblock\n");
        ExFreePool(sb);
        return STATUS_UNRECOGNIZED_VOLUME;
    }

    i = 0;
    valid_superblocks = 0;

    while (superblock_addrs[i] > 0) {
        uint32_t crc32;

        if (i > 0 && superblock_addrs[i] + to_read > length)
            break;

        Status = sync_read_phys(device, fileobj, superblock_addrs[i], to_read, (PUCHAR)sb, false);
        if (!NT_SUCCESS(Status)) {
            ERR("Failed to read superblock %u: %08x\n", i, Status);
            ExFreePool(sb);
            return Status;
        }

        if (sb->magic != BTRFS_MAGIC) {
            if (i == 0) {
                TRACE("not a BTRFS volume\n");
                ExFreePool(sb);
                return STATUS_UNRECOGNIZED_VOLUME;
            }
        } else {
            TRACE("got superblock %u!\n", i);

            crc32 = ~calc_crc32c(0xffffffff, (uint8_t*)&sb->uuid, (ULONG)sizeof(superblock) - sizeof(sb->checksum));

            if (crc32 != *((uint32_t*)sb->checksum))
                WARN("crc32 was %08x, expected %08x\n", crc32, *((uint32_t*)sb->checksum));
            else if (sb->sector_size == 0)
                WARN("superblock sector size was 0\n");
            else if (sb->node_size < sizeof(tree_header) + sizeof(internal_node) || sb->node_size > 0x10000)
                WARN("invalid node size %x\n", sb->node_size);
            else if ((sb->node_size % sb->sector_size) != 0)
                WARN("node size %x was not a multiple of sector_size %x\n", sb->node_size, sb->sector_size);
            else if (valid_superblocks == 0 || sb->generation > Vcb->superblock.generation) {
                RtlCopyMemory(&Vcb->superblock, sb, sizeof(superblock));
                valid_superblocks++;
            }
        }

        i++;
    }

    ExFreePool(sb);

    if (valid_superblocks == 0) {
        ERR("could not find any valid superblocks\n");
        return STATUS_INTERNAL_ERROR;
    }

    TRACE("label is %s\n", Vcb->superblock.label);

    return STATUS_SUCCESS;
}

NTSTATUS dev_ioctl(_In_ PDEVICE_OBJECT DeviceObject, _In_ ULONG ControlCode, _In_reads_bytes_opt_(InputBufferSize) PVOID InputBuffer, _In_ ULONG InputBufferSize,
                   _Out_writes_bytes_opt_(OutputBufferSize) PVOID OutputBuffer, _In_ ULONG OutputBufferSize, _In_ bool Override, _Out_opt_ IO_STATUS_BLOCK* iosb) {
    PIRP Irp;
    KEVENT Event;
    NTSTATUS Status;
    PIO_STACK_LOCATION IrpSp;
    IO_STATUS_BLOCK IoStatus;

    KeInitializeEvent(&Event, NotificationEvent, false);

    Irp = IoBuildDeviceIoControlRequest(ControlCode,
                                        DeviceObject,
                                        InputBuffer,
                                        InputBufferSize,
                                        OutputBuffer,
                                        OutputBufferSize,
                                        false,
                                        &Event,
                                        &IoStatus);

    if (!Irp) return STATUS_INSUFFICIENT_RESOURCES;

    if (Override) {
        IrpSp = IoGetNextIrpStackLocation(Irp);
        IrpSp->Flags |= SL_OVERRIDE_VERIFY_VOLUME;
    }

    Status = IoCallDriver(DeviceObject, Irp);

    if (Status == STATUS_PENDING) {
        KeWaitForSingleObject(&Event, Executive, KernelMode, false, NULL);
        Status = IoStatus.Status;
    }

    if (iosb)
        *iosb = IoStatus;

    return Status;
}

_Requires_exclusive_lock_held_(Vcb->tree_lock)
static NTSTATUS add_root(_Inout_ device_extension* Vcb, _In_ uint64_t id, _In_ uint64_t addr,
                         _In_ uint64_t generation, _In_opt_ traverse_ptr* tp) {
    root* r = ExAllocatePoolWithTag(PagedPool, sizeof(root), ALLOC_TAG);
    if (!r) {
        ERR("out of memory\n");
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    r->id = id;
    r->dirty = false;
    r->received = false;
    r->reserved = NULL;
    r->treeholder.address = addr;
    r->treeholder.tree = NULL;
    r->treeholder.generation = generation;
    r->parent = 0;
    r->send_ops = 0;
    r->fcbs_version = 0;
    r->checked_for_orphans = false;
    InitializeListHead(&r->fcbs);
    RtlZeroMemory(r->fcbs_ptrs, sizeof(LIST_ENTRY*) * 256);

    r->nonpaged = ExAllocatePoolWithTag(NonPagedPool, sizeof(root_nonpaged), ALLOC_TAG);
    if (!r->nonpaged) {
        ERR("out of memory\n");
        ExFreePool(r);
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    ExInitializeResourceLite(&r->nonpaged->load_tree_lock);

    r->lastinode = 0;

    if (tp) {
        RtlCopyMemory(&r->root_item, tp->item->data, min(sizeof(ROOT_ITEM), tp->item->size));
        if (tp->item->size < sizeof(ROOT_ITEM))
            RtlZeroMemory(((uint8_t*)&r->root_item) + tp->item->size, sizeof(ROOT_ITEM) - tp->item->size);
    } else
        RtlZeroMemory(&r->root_item, sizeof(ROOT_ITEM));

    if (!Vcb->readonly && (r->id == BTRFS_ROOT_ROOT || r->id == BTRFS_ROOT_FSTREE || (r->id >= 0x100 && !(r->id & 0xf000000000000000)))) { // FS tree root
        // FIXME - don't call this if subvol is readonly (though we will have to if we ever toggle this flag)
        get_last_inode(Vcb, r, NULL);

        if (r->id == BTRFS_ROOT_ROOT && r->lastinode < 0x100)
            r->lastinode = 0x100;
    }

    InsertTailList(&Vcb->roots, &r->list_entry);

    switch (r->id) {
        case BTRFS_ROOT_ROOT:
            Vcb->root_root = r;
            break;

        case BTRFS_ROOT_EXTENT:
            Vcb->extent_root = r;
            break;

        case BTRFS_ROOT_CHUNK:
            Vcb->chunk_root = r;
            break;

        case BTRFS_ROOT_DEVTREE:
            Vcb->dev_root = r;
            break;

        case BTRFS_ROOT_CHECKSUM:
            Vcb->checksum_root = r;
            break;

        case BTRFS_ROOT_UUID:
            Vcb->uuid_root = r;
            break;

        case BTRFS_ROOT_FREE_SPACE:
            Vcb->space_root = r;
            break;

        case BTRFS_ROOT_DATA_RELOC:
            Vcb->data_reloc_root = r;
            break;
    }

    return STATUS_SUCCESS;
}

static NTSTATUS look_for_roots(_Requires_exclusive_lock_held_(_Curr_->tree_lock) _In_ device_extension* Vcb, _In_opt_ PIRP Irp) {
    traverse_ptr tp, next_tp;
    KEY searchkey;
    bool b;
    NTSTATUS Status;

    searchkey.obj_id = 0;
    searchkey.obj_type = 0;
    searchkey.offset = 0;

    Status = find_item(Vcb, Vcb->root_root, &tp, &searchkey, false, Irp);
    if (!NT_SUCCESS(Status)) {
        ERR("error - find_item returned %08x\n", Status);
        return Status;
    }

    do {
        TRACE("(%I64x,%x,%I64x)\n", tp.item->key.obj_id, tp.item->key.obj_type, tp.item->key.offset);

        if (tp.item->key.obj_type == TYPE_ROOT_ITEM) {
            ROOT_ITEM* ri = (ROOT_ITEM*)tp.item->data;

            if (tp.item->size < offsetof(ROOT_ITEM, byte_limit)) {
                ERR("(%I64x,%x,%I64x) was %u bytes, expected at least %u\n", tp.item->key.obj_id, tp.item->key.obj_type, tp.item->key.offset, tp.item->size, offsetof(ROOT_ITEM, byte_limit));
            } else {
                TRACE("root %I64x - address %I64x\n", tp.item->key.obj_id, ri->block_number);

                Status = add_root(Vcb, tp.item->key.obj_id, ri->block_number, ri->generation, &tp);
                if (!NT_SUCCESS(Status)) {
                    ERR("add_root returned %08x\n", Status);
                    return Status;
                }
            }
        } else if (tp.item->key.obj_type == TYPE_ROOT_BACKREF && !IsListEmpty(&Vcb->roots)) {
            root* lastroot = CONTAINING_RECORD(Vcb->roots.Blink, root, list_entry);

            if (lastroot->id == tp.item->key.obj_id)
                lastroot->parent = tp.item->key.offset;
        }

        b = find_next_item(Vcb, &tp, &next_tp, false, Irp);

        if (b)
            tp = next_tp;
    } while (b);

    if (!Vcb->readonly && !Vcb->data_reloc_root) {
        root* reloc_root;
        INODE_ITEM* ii;
        uint16_t irlen;
        INODE_REF* ir;
        LARGE_INTEGER time;
        BTRFS_TIME now;

        WARN("data reloc root doesn't exist, creating it\n");

        Status = create_root(Vcb, BTRFS_ROOT_DATA_RELOC, &reloc_root, false, 0, Irp);

        if (!NT_SUCCESS(Status)) {
            ERR("create_root returned %08x\n", Status);
            return Status;
        }

        reloc_root->root_item.inode.generation = 1;
        reloc_root->root_item.inode.st_size = 3;
        reloc_root->root_item.inode.st_blocks = Vcb->superblock.node_size;
        reloc_root->root_item.inode.st_nlink = 1;
        reloc_root->root_item.inode.st_mode = 040755;
        reloc_root->root_item.inode.flags = 0xffffffff80000000;
        reloc_root->root_item.objid = SUBVOL_ROOT_INODE;
        reloc_root->root_item.bytes_used = Vcb->superblock.node_size;

        ii = ExAllocatePoolWithTag(PagedPool, sizeof(INODE_ITEM), ALLOC_TAG);
        if (!ii) {
            ERR("out of memory\n");
            return STATUS_INSUFFICIENT_RESOURCES;
        }

        KeQuerySystemTime(&time);
        win_time_to_unix(time, &now);

        RtlZeroMemory(ii, sizeof(INODE_ITEM));
        ii->generation = Vcb->superblock.generation;
        ii->st_blocks = Vcb->superblock.node_size;
        ii->st_nlink = 1;
        ii->st_mode = 040755;
        ii->st_atime = now;
        ii->st_ctime = now;
        ii->st_mtime = now;

        Status = insert_tree_item(Vcb, reloc_root, SUBVOL_ROOT_INODE, TYPE_INODE_ITEM, 0, ii, sizeof(INODE_ITEM), NULL, Irp);
        if (!NT_SUCCESS(Status)) {
            ERR("insert_tree_item returned %08x\n", Status);
            ExFreePool(ii);
            return Status;
        }

        irlen = (uint16_t)offsetof(INODE_REF, name[0]) + 2;
        ir = ExAllocatePoolWithTag(PagedPool, irlen, ALLOC_TAG);
        if (!ir) {
            ERR("out of memory\n");
            return STATUS_INSUFFICIENT_RESOURCES;
        }

        ir->index = 0;
        ir->n = 2;
        ir->name[0] = '.';
        ir->name[1] = '.';

        Status = insert_tree_item(Vcb, reloc_root, SUBVOL_ROOT_INODE, TYPE_INODE_REF, SUBVOL_ROOT_INODE, ir, irlen, NULL, Irp);
        if (!NT_SUCCESS(Status)) {
            ERR("insert_tree_item returned %08x\n", Status);
            ExFreePool(ir);
            return Status;
        }

        Vcb->data_reloc_root = reloc_root;
        Vcb->need_write = true;
    }

    return STATUS_SUCCESS;
}

static NTSTATUS find_disk_holes(_In_ _Requires_lock_held_(_Curr_->tree_lock) device_extension* Vcb, _In_ device* dev, _In_opt_ PIRP Irp) {
    KEY searchkey;
    traverse_ptr tp, next_tp;
    bool b;
    uint64_t lastaddr;
    NTSTATUS Status;

    InitializeListHead(&dev->space);

    searchkey.obj_id = 0;
    searchkey.obj_type = TYPE_DEV_STATS;
    searchkey.offset = dev->devitem.dev_id;

    Status = find_item(Vcb, Vcb->dev_root, &tp, &searchkey, false, Irp);
    if (NT_SUCCESS(Status) && !keycmp(tp.item->key, searchkey))
        RtlCopyMemory(dev->stats, tp.item->data, min(sizeof(uint64_t) * 5, tp.item->size));

    searchkey.obj_id = dev->devitem.dev_id;
    searchkey.obj_type = TYPE_DEV_EXTENT;
    searchkey.offset = 0;

    Status = find_item(Vcb, Vcb->dev_root, &tp, &searchkey, false, Irp);
    if (!NT_SUCCESS(Status)) {
        ERR("error - find_item returned %08x\n", Status);
        return Status;
    }

    lastaddr = 0;

    do {
        if (tp.item->key.obj_id == dev->devitem.dev_id && tp.item->key.obj_type == TYPE_DEV_EXTENT) {
            if (tp.item->size >= sizeof(DEV_EXTENT)) {
                DEV_EXTENT* de = (DEV_EXTENT*)tp.item->data;

                if (tp.item->key.offset > lastaddr) {
                    Status = add_space_entry(&dev->space, NULL, lastaddr, tp.item->key.offset - lastaddr);
                    if (!NT_SUCCESS(Status)) {
                        ERR("add_space_entry returned %08x\n", Status);
                        return Status;
                    }
                }

                lastaddr = tp.item->key.offset + de->length;
            } else {
                ERR("(%I64x,%x,%I64x) was %u bytes, expected %u\n", tp.item->key.obj_id, tp.item->key.obj_type, tp.item->key.offset, tp.item->size, sizeof(DEV_EXTENT));
            }
        }

        b = find_next_item(Vcb, &tp, &next_tp, false, Irp);

        if (b) {
            tp = next_tp;
            if (tp.item->key.obj_id > searchkey.obj_id || tp.item->key.obj_type > searchkey.obj_type)
                break;
        }
    } while (b);

    if (lastaddr < dev->devitem.num_bytes) {
        Status = add_space_entry(&dev->space, NULL, lastaddr, dev->devitem.num_bytes - lastaddr);
        if (!NT_SUCCESS(Status)) {
            ERR("add_space_entry returned %08x\n", Status);
            return Status;
        }
    }

    // The Linux driver doesn't like to allocate chunks within the first megabyte of a device.

    space_list_subtract2(&dev->space, NULL, 0, 0x100000, NULL, NULL);

    return STATUS_SUCCESS;
}

static void add_device_to_list(_In_ device_extension* Vcb, _In_ device* dev) {
    LIST_ENTRY* le;

    le = Vcb->devices.Flink;

    while (le != &Vcb->devices) {
        device* dev2 = CONTAINING_RECORD(le, device, list_entry);

        if (dev2->devitem.dev_id > dev->devitem.dev_id) {
            InsertHeadList(le->Blink, &dev->list_entry);
            return;
        }

        le = le->Flink;
    }

    InsertTailList(&Vcb->devices, &dev->list_entry);
}

_Ret_maybenull_
device* find_device_from_uuid(_In_ device_extension* Vcb, _In_ BTRFS_UUID* uuid) {
    volume_device_extension* vde;
    pdo_device_extension* pdode;
    LIST_ENTRY* le;

    le = Vcb->devices.Flink;
    while (le != &Vcb->devices) {
        device* dev = CONTAINING_RECORD(le, device, list_entry);

        TRACE("device %I64x, uuid %02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x\n", dev->devitem.dev_id,
            dev->devitem.device_uuid.uuid[0], dev->devitem.device_uuid.uuid[1], dev->devitem.device_uuid.uuid[2], dev->devitem.device_uuid.uuid[3], dev->devitem.device_uuid.uuid[4], dev->devitem.device_uuid.uuid[5], dev->devitem.device_uuid.uuid[6], dev->devitem.device_uuid.uuid[7],
            dev->devitem.device_uuid.uuid[8], dev->devitem.device_uuid.uuid[9], dev->devitem.device_uuid.uuid[10], dev->devitem.device_uuid.uuid[11], dev->devitem.device_uuid.uuid[12], dev->devitem.device_uuid.uuid[13], dev->devitem.device_uuid.uuid[14], dev->devitem.device_uuid.uuid[15]);

        if (RtlCompareMemory(&dev->devitem.device_uuid, uuid, sizeof(BTRFS_UUID)) == sizeof(BTRFS_UUID)) {
            TRACE("returning device %I64x\n", dev->devitem.dev_id);
            return dev;
        }

        le = le->Flink;
    }

    vde = Vcb->vde;

    if (!vde)
        goto end;

    pdode = vde->pdode;

    ExAcquireResourceSharedLite(&pdode->child_lock, true);

    if (Vcb->devices_loaded < Vcb->superblock.num_devices) {
        le = pdode->children.Flink;

        while (le != &pdode->children) {
            volume_child* vc = CONTAINING_RECORD(le, volume_child, list_entry);

            if (RtlCompareMemory(uuid, &vc->uuid, sizeof(BTRFS_UUID)) == sizeof(BTRFS_UUID)) {
                device* dev;

                dev = ExAllocatePoolWithTag(NonPagedPool, sizeof(device), ALLOC_TAG);
                if (!dev) {
                    ExReleaseResourceLite(&pdode->child_lock);
                    ERR("out of memory\n");
                    return NULL;
                }

                RtlZeroMemory(dev, sizeof(device));
                dev->devobj = vc->devobj;
                dev->fileobj = vc->fileobj;
                dev->devitem.device_uuid = *uuid;
                dev->devitem.dev_id = vc->devid;
                dev->devitem.num_bytes = vc->size;
                dev->seeding = vc->seeding;
                dev->readonly = dev->seeding;
                dev->reloc = false;
                dev->removable = false;
                dev->disk_num = vc->disk_num;
                dev->part_num = vc->part_num;
                dev->num_trim_entries = 0;
                InitializeListHead(&dev->trim_list);

                add_device_to_list(Vcb, dev);
                Vcb->devices_loaded++;

                ExReleaseResourceLite(&pdode->child_lock);

                return dev;
            }

            le = le->Flink;
        }
    }

    ExReleaseResourceLite(&pdode->child_lock);

end:
    WARN("could not find device with uuid %02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x\n",
         uuid->uuid[0], uuid->uuid[1], uuid->uuid[2], uuid->uuid[3], uuid->uuid[4], uuid->uuid[5], uuid->uuid[6], uuid->uuid[7],
         uuid->uuid[8], uuid->uuid[9], uuid->uuid[10], uuid->uuid[11], uuid->uuid[12], uuid->uuid[13], uuid->uuid[14], uuid->uuid[15]);

    return NULL;
}

static bool is_device_removable(_In_ PDEVICE_OBJECT devobj) {
    NTSTATUS Status;
    STORAGE_HOTPLUG_INFO shi;

    Status = dev_ioctl(devobj, IOCTL_STORAGE_GET_HOTPLUG_INFO, NULL, 0, &shi, sizeof(STORAGE_HOTPLUG_INFO), true, NULL);

    if (!NT_SUCCESS(Status)) {
        ERR("dev_ioctl returned %08x\n", Status);
        return false;
    }

    return shi.MediaRemovable != 0 ? true : false;
}

static ULONG get_device_change_count(_In_ PDEVICE_OBJECT devobj) {
    NTSTATUS Status;
    ULONG cc;
    IO_STATUS_BLOCK iosb;

    Status = dev_ioctl(devobj, IOCTL_STORAGE_CHECK_VERIFY, NULL, 0, &cc, sizeof(ULONG), true, &iosb);

    if (!NT_SUCCESS(Status)) {
        ERR("dev_ioctl returned %08x\n", Status);
        return 0;
    }

    if (iosb.Information < sizeof(ULONG)) {
        ERR("iosb.Information was too short\n");
        return 0;
    }

    return cc;
}

void init_device(_In_ device_extension* Vcb, _Inout_ device* dev, _In_ bool get_nums) {
    NTSTATUS Status;
    ULONG aptelen;
    ATA_PASS_THROUGH_EX* apte;
    STORAGE_PROPERTY_QUERY spq;
    DEVICE_TRIM_DESCRIPTOR dtd;

    dev->removable = is_device_removable(dev->devobj);
    dev->change_count = dev->removable ? get_device_change_count(dev->devobj) : 0;

    if (get_nums) {
        STORAGE_DEVICE_NUMBER sdn;

        Status = dev_ioctl(dev->devobj, IOCTL_STORAGE_GET_DEVICE_NUMBER, NULL, 0,
                           &sdn, sizeof(STORAGE_DEVICE_NUMBER), true, NULL);

        if (!NT_SUCCESS(Status)) {
            WARN("IOCTL_STORAGE_GET_DEVICE_NUMBER returned %08x\n", Status);
            dev->disk_num = 0xffffffff;
            dev->part_num = 0xffffffff;
        } else {
            dev->disk_num = sdn.DeviceNumber;
            dev->part_num = sdn.PartitionNumber;
        }
    }

    dev->trim = false;
    dev->readonly = dev->seeding;
    dev->reloc = false;
    dev->num_trim_entries = 0;
    dev->stats_changed = false;
    InitializeListHead(&dev->trim_list);

    if (!dev->readonly) {
        Status = dev_ioctl(dev->devobj, IOCTL_DISK_IS_WRITABLE, NULL, 0,
                        NULL, 0, true, NULL);
        if (Status == STATUS_MEDIA_WRITE_PROTECTED)
            dev->readonly = true;
    }

    aptelen = sizeof(ATA_PASS_THROUGH_EX) + 512;
    apte = ExAllocatePoolWithTag(NonPagedPool, aptelen, ALLOC_TAG);
    if (!apte) {
        ERR("out of memory\n");
        return;
    }

    RtlZeroMemory(apte, aptelen);

    apte->Length = sizeof(ATA_PASS_THROUGH_EX);
    apte->AtaFlags = ATA_FLAGS_DATA_IN;
    apte->DataTransferLength = aptelen - sizeof(ATA_PASS_THROUGH_EX);
    apte->TimeOutValue = 3;
    apte->DataBufferOffset = apte->Length;
    apte->CurrentTaskFile[6] = IDE_COMMAND_IDENTIFY;

    Status = dev_ioctl(dev->devobj, IOCTL_ATA_PASS_THROUGH, apte, aptelen,
                       apte, aptelen, true, NULL);

    if (!NT_SUCCESS(Status))
        TRACE("IOCTL_ATA_PASS_THROUGH returned %08x for IDENTIFY DEVICE\n", Status);
    else {
        IDENTIFY_DEVICE_DATA* idd = (IDENTIFY_DEVICE_DATA*)((uint8_t*)apte + sizeof(ATA_PASS_THROUGH_EX));

        if (idd->CommandSetSupport.FlushCache) {
            dev->can_flush = true;
            TRACE("FLUSH CACHE supported\n");
        } else
            TRACE("FLUSH CACHE not supported\n");
    }

    ExFreePool(apte);

#ifdef DEBUG_TRIM_EMULATION
    dev->trim = true;
    Vcb->trim = true;
#else
    spq.PropertyId = StorageDeviceTrimProperty;
    spq.QueryType = PropertyStandardQuery;
    spq.AdditionalParameters[0] = 0;

    Status = dev_ioctl(dev->devobj, IOCTL_STORAGE_QUERY_PROPERTY, &spq, sizeof(STORAGE_PROPERTY_QUERY),
                       &dtd, sizeof(DEVICE_TRIM_DESCRIPTOR), true, NULL);

    if (NT_SUCCESS(Status)) {
        if (dtd.TrimEnabled) {
            dev->trim = true;
            Vcb->trim = true;
            TRACE("TRIM supported\n");
        } else
            TRACE("TRIM not supported\n");
    }
#endif

    RtlZeroMemory(dev->stats, sizeof(uint64_t) * 5);
}

static NTSTATUS load_chunk_root(_In_ _Requires_lock_held_(_Curr_->tree_lock) device_extension* Vcb, _In_opt_ PIRP Irp) {
    traverse_ptr tp, next_tp;
    KEY searchkey;
    bool b;
    chunk* c;
    NTSTATUS Status;

    searchkey.obj_id = 0;
    searchkey.obj_type = 0;
    searchkey.offset = 0;

    Vcb->data_flags = 0;
    Vcb->metadata_flags = 0;
    Vcb->system_flags = 0;

    Status = find_item(Vcb, Vcb->chunk_root, &tp, &searchkey, false, Irp);
    if (!NT_SUCCESS(Status)) {
        ERR("error - find_item returned %08x\n", Status);
        return Status;
    }

    do {
        TRACE("(%I64x,%x,%I64x)\n", tp.item->key.obj_id, tp.item->key.obj_type, tp.item->key.offset);

        if (tp.item->key.obj_id == 1 && tp.item->key.obj_type == TYPE_DEV_ITEM) {
            if (tp.item->size < sizeof(DEV_ITEM)) {
                ERR("(%I64x,%x,%I64x) was %u bytes, expected %u\n", tp.item->key.obj_id, tp.item->key.obj_type, tp.item->key.offset, tp.item->size, sizeof(DEV_ITEM));
            } else {
                DEV_ITEM* di = (DEV_ITEM*)tp.item->data;
                LIST_ENTRY* le;
                bool done = false;

                le = Vcb->devices.Flink;
                while (le != &Vcb->devices) {
                    device* dev = CONTAINING_RECORD(le, device, list_entry);

                    if (dev->devobj && RtlCompareMemory(&dev->devitem.device_uuid, &di->device_uuid, sizeof(BTRFS_UUID)) == sizeof(BTRFS_UUID)) {
                        RtlCopyMemory(&dev->devitem, tp.item->data, min(tp.item->size, sizeof(DEV_ITEM)));

                        if (le != Vcb->devices.Flink)
                            init_device(Vcb, dev, true);

                        done = true;
                        break;
                    }

                    le = le->Flink;
                }

                if (!done && Vcb->vde) {
                    volume_device_extension* vde = Vcb->vde;
                    pdo_device_extension* pdode = vde->pdode;

                    ExAcquireResourceSharedLite(&pdode->child_lock, true);

                    if (Vcb->devices_loaded < Vcb->superblock.num_devices) {
                        le = pdode->children.Flink;

                        while (le != &pdode->children) {
                            volume_child* vc = CONTAINING_RECORD(le, volume_child, list_entry);

                            if (RtlCompareMemory(&di->device_uuid, &vc->uuid, sizeof(BTRFS_UUID)) == sizeof(BTRFS_UUID)) {
                                device* dev;

                                dev = ExAllocatePoolWithTag(NonPagedPool, sizeof(device), ALLOC_TAG);
                                if (!dev) {
                                    ExReleaseResourceLite(&pdode->child_lock);
                                    ERR("out of memory\n");
                                    return STATUS_INSUFFICIENT_RESOURCES;
                                }

                                RtlZeroMemory(dev, sizeof(device));

                                dev->devobj = vc->devobj;
                                dev->fileobj = vc->fileobj;
                                RtlCopyMemory(&dev->devitem, di, min(tp.item->size, sizeof(DEV_ITEM)));
                                dev->seeding = vc->seeding;
                                init_device(Vcb, dev, false);

                                if (dev->devitem.num_bytes > vc->size) {
                                    WARN("device %I64x: DEV_ITEM says %I64x bytes, but Windows only reports %I64x\n", tp.item->key.offset,
                                         dev->devitem.num_bytes, vc->size);

                                    dev->devitem.num_bytes = vc->size;
                                }

                                dev->disk_num = vc->disk_num;
                                dev->part_num = vc->part_num;
                                add_device_to_list(Vcb, dev);
                                Vcb->devices_loaded++;

                                done = true;
                                break;
                            }

                            le = le->Flink;
                        }

                        if (!done) {
                            if (!Vcb->options.allow_degraded) {
                                ERR("volume not found: device %I64x, uuid %02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x\n", tp.item->key.offset,
                                    di->device_uuid.uuid[0], di->device_uuid.uuid[1], di->device_uuid.uuid[2], di->device_uuid.uuid[3], di->device_uuid.uuid[4], di->device_uuid.uuid[5], di->device_uuid.uuid[6], di->device_uuid.uuid[7],
                                    di->device_uuid.uuid[8], di->device_uuid.uuid[9], di->device_uuid.uuid[10], di->device_uuid.uuid[11], di->device_uuid.uuid[12], di->device_uuid.uuid[13], di->device_uuid.uuid[14], di->device_uuid.uuid[15]);
                            } else {
                                device* dev;

                                dev = ExAllocatePoolWithTag(NonPagedPool, sizeof(device), ALLOC_TAG);
                                if (!dev) {
                                    ExReleaseResourceLite(&pdode->child_lock);
                                    ERR("out of memory\n");
                                    return STATUS_INSUFFICIENT_RESOURCES;
                                }

                                RtlZeroMemory(dev, sizeof(device));

                                // Missing device, so we keep dev->devobj as NULL
                                RtlCopyMemory(&dev->devitem, di, min(tp.item->size, sizeof(DEV_ITEM)));
                                InitializeListHead(&dev->trim_list);

                                add_device_to_list(Vcb, dev);
                                Vcb->devices_loaded++;
                            }
                        }
                    } else
                        ERR("unexpected device %I64x found\n", tp.item->key.offset);

                    ExReleaseResourceLite(&pdode->child_lock);
                }
            }
        } else if (tp.item->key.obj_type == TYPE_CHUNK_ITEM) {
            if (tp.item->size < sizeof(CHUNK_ITEM)) {
                ERR("(%I64x,%x,%I64x) was %u bytes, expected at least %u\n", tp.item->key.obj_id, tp.item->key.obj_type, tp.item->key.offset, tp.item->size, sizeof(CHUNK_ITEM));
            } else {
                c = ExAllocatePoolWithTag(NonPagedPool, sizeof(chunk), ALLOC_TAG);

                if (!c) {
                    ERR("out of memory\n");
                    return STATUS_INSUFFICIENT_RESOURCES;
                }

                c->size = tp.item->size;
                c->offset = tp.item->key.offset;
                c->used = c->oldused = 0;
                c->cache = c->old_cache = NULL;
                c->created = false;
                c->readonly = false;
                c->reloc = false;
                c->cache_loaded = false;
                c->changed = false;
                c->space_changed = false;
                c->balance_num = 0;

                c->chunk_item = ExAllocatePoolWithTag(NonPagedPool, tp.item->size, ALLOC_TAG);

                if (!c->chunk_item) {
                    ERR("out of memory\n");
                    ExFreePool(c);
                    return STATUS_INSUFFICIENT_RESOURCES;
                }

                RtlCopyMemory(c->chunk_item, tp.item->data, tp.item->size);

                if (c->chunk_item->type & BLOCK_FLAG_DATA && c->chunk_item->type > Vcb->data_flags)
                    Vcb->data_flags = c->chunk_item->type;

                if (c->chunk_item->type & BLOCK_FLAG_METADATA && c->chunk_item->type > Vcb->metadata_flags)
                    Vcb->metadata_flags = c->chunk_item->type;

                if (c->chunk_item->type & BLOCK_FLAG_SYSTEM && c->chunk_item->type > Vcb->system_flags)
                    Vcb->system_flags = c->chunk_item->type;

                if (c->chunk_item->type & BLOCK_FLAG_RAID10) {
                    if (c->chunk_item->sub_stripes == 0 || c->chunk_item->sub_stripes > c->chunk_item->num_stripes) {
                        ERR("chunk %I64x: invalid stripes (num_stripes %u, sub_stripes %u)\n", c->offset, c->chunk_item->num_stripes, c->chunk_item->sub_stripes);
                        ExFreePool(c->chunk_item);
                        ExFreePool(c);
                        return STATUS_INTERNAL_ERROR;
                    }
                }

                if (c->chunk_item->num_stripes > 0) {
                    CHUNK_ITEM_STRIPE* cis = (CHUNK_ITEM_STRIPE*)&c->chunk_item[1];
                    uint16_t i;

                    c->devices = ExAllocatePoolWithTag(NonPagedPool, sizeof(device*) * c->chunk_item->num_stripes, ALLOC_TAG);

                    if (!c->devices) {
                        ERR("out of memory\n");
                        ExFreePool(c->chunk_item);
                        ExFreePool(c);
                        return STATUS_INSUFFICIENT_RESOURCES;
                    }

                    for (i = 0; i < c->chunk_item->num_stripes; i++) {
                        c->devices[i] = find_device_from_uuid(Vcb, &cis[i].dev_uuid);
                        TRACE("device %I64u = %p\n", i, c->devices[i]);

                        if (!c->devices[i]) {
                            ERR("missing device\n");
                            ExFreePool(c->chunk_item);
                            ExFreePool(c);
                            return STATUS_INTERNAL_ERROR;
                        }

                        if (c->devices[i]->readonly)
                            c->readonly = true;
                    }
                } else {
                    ERR("chunk %I64x: number of stripes is 0\n", c->offset);
                    ExFreePool(c->chunk_item);
                    ExFreePool(c);
                    return STATUS_INTERNAL_ERROR;
                }

                ExInitializeResourceLite(&c->lock);
                ExInitializeResourceLite(&c->changed_extents_lock);

                InitializeListHead(&c->space);
                InitializeListHead(&c->space_size);
                InitializeListHead(&c->deleting);
                InitializeListHead(&c->changed_extents);

                InitializeListHead(&c->range_locks);
                ExInitializeResourceLite(&c->range_locks_lock);
                KeInitializeEvent(&c->range_locks_event, NotificationEvent, false);

                InitializeListHead(&c->partial_stripes);
                ExInitializeResourceLite(&c->partial_stripes_lock);

                c->last_alloc_set = false;

                c->last_stripe = 0;

                InsertTailList(&Vcb->chunks, &c->list_entry);

                c->list_entry_balance.Flink = NULL;
            }
        }

        b = find_next_item(Vcb, &tp, &next_tp, false, Irp);

        if (b)
            tp = next_tp;
    } while (b);

    Vcb->log_to_phys_loaded = true;

    if (Vcb->data_flags == 0)
        Vcb->data_flags = BLOCK_FLAG_DATA | (Vcb->superblock.num_devices > 1 ? BLOCK_FLAG_RAID0 : 0);

    if (Vcb->metadata_flags == 0)
        Vcb->metadata_flags = BLOCK_FLAG_METADATA | (Vcb->superblock.num_devices > 1 ? BLOCK_FLAG_RAID1 : BLOCK_FLAG_DUPLICATE);

    if (Vcb->system_flags == 0)
        Vcb->system_flags = BLOCK_FLAG_SYSTEM | (Vcb->superblock.num_devices > 1 ? BLOCK_FLAG_RAID1 : BLOCK_FLAG_DUPLICATE);

    if (Vcb->superblock.incompat_flags & BTRFS_INCOMPAT_FLAGS_MIXED_GROUPS) {
        Vcb->metadata_flags |= BLOCK_FLAG_DATA;
        Vcb->data_flags = Vcb->metadata_flags;
    }

    return STATUS_SUCCESS;
}

void protect_superblocks(_Inout_ chunk* c) {
    uint16_t i = 0, j;
    uint64_t off_start, off_end;

    // The Linux driver also protects all the space before the first superblock.
    // I realize this confuses physical and logical addresses, but this is what btrfs-progs does -
    // evidently Linux assumes the chunk at 0 is always SINGLE.
    if (c->offset < superblock_addrs[0])
        space_list_subtract(c, false, c->offset, superblock_addrs[0] - c->offset, NULL);

    while (superblock_addrs[i] != 0) {
        CHUNK_ITEM* ci = c->chunk_item;
        CHUNK_ITEM_STRIPE* cis = (CHUNK_ITEM_STRIPE*)&ci[1];

        if (ci->type & BLOCK_FLAG_RAID0 || ci->type & BLOCK_FLAG_RAID10) {
            for (j = 0; j < ci->num_stripes; j++) {
                uint16_t sub_stripes = max(ci->sub_stripes, 1);

                if (cis[j].offset + (ci->size * ci->num_stripes / sub_stripes) > superblock_addrs[i] && cis[j].offset <= superblock_addrs[i] + sizeof(superblock)) {
#ifdef _DEBUG
                    uint64_t startoff;
                    uint16_t startoffstripe;
#endif

                    TRACE("cut out superblock in chunk %I64x\n", c->offset);

                    off_start = superblock_addrs[i] - cis[j].offset;
                    off_start -= off_start % ci->stripe_length;
                    off_start *= ci->num_stripes / sub_stripes;
                    off_start += (j / sub_stripes) * ci->stripe_length;

                    off_end = off_start + ci->stripe_length;

#ifdef _DEBUG
                    get_raid0_offset(off_start, ci->stripe_length, ci->num_stripes / sub_stripes, &startoff, &startoffstripe);
                    TRACE("j = %u, startoffstripe = %u\n", j, startoffstripe);
                    TRACE("startoff = %I64x, superblock = %I64x\n", startoff + cis[j].offset, superblock_addrs[i]);
#endif

                    space_list_subtract(c, false, c->offset + off_start, off_end - off_start, NULL);
                }
            }
        } else if (ci->type & BLOCK_FLAG_RAID5) {
            uint64_t stripe_size = ci->size / (ci->num_stripes - 1);

            for (j = 0; j < ci->num_stripes; j++) {
                if (cis[j].offset + stripe_size > superblock_addrs[i] && cis[j].offset <= superblock_addrs[i] + sizeof(superblock)) {
                    TRACE("cut out superblock in chunk %I64x\n", c->offset);

                    off_start = superblock_addrs[i] - cis[j].offset;
                    off_start -= off_start % ci->stripe_length;
                    off_start *= ci->num_stripes - 1;

                    off_end = sector_align(superblock_addrs[i] - cis[j].offset + sizeof(superblock), ci->stripe_length);
                    off_end *= ci->num_stripes - 1;

                    TRACE("cutting out %I64x, size %I64x\n", c->offset + off_start, off_end - off_start);

                    space_list_subtract(c, false, c->offset + off_start, off_end - off_start, NULL);
                }
            }
        } else if (ci->type & BLOCK_FLAG_RAID6) {
            uint64_t stripe_size = ci->size / (ci->num_stripes - 2);

            for (j = 0; j < ci->num_stripes; j++) {
                if (cis[j].offset + stripe_size > superblock_addrs[i] && cis[j].offset <= superblock_addrs[i] + sizeof(superblock)) {
                    TRACE("cut out superblock in chunk %I64x\n", c->offset);

                    off_start = superblock_addrs[i] - cis[j].offset;
                    off_start -= off_start % ci->stripe_length;
                    off_start *= ci->num_stripes - 2;

                    off_end = sector_align(superblock_addrs[i] - cis[j].offset + sizeof(superblock), ci->stripe_length);
                    off_end *= ci->num_stripes - 2;

                    TRACE("cutting out %I64x, size %I64x\n", c->offset + off_start, off_end - off_start);

                    space_list_subtract(c, false, c->offset + off_start, off_end - off_start, NULL);
                }
            }
        } else { // SINGLE, DUPLICATE, RAID1
            for (j = 0; j < ci->num_stripes; j++) {
                if (cis[j].offset + ci->size > superblock_addrs[i] && cis[j].offset <= superblock_addrs[i] + sizeof(superblock)) {
                    TRACE("cut out superblock in chunk %I64x\n", c->offset);

                    // The Linux driver protects the whole stripe in which the superblock lives

                    off_start = ((superblock_addrs[i] - cis[j].offset) / c->chunk_item->stripe_length) * c->chunk_item->stripe_length;
                    off_end = sector_align(superblock_addrs[i] - cis[j].offset + sizeof(superblock), c->chunk_item->stripe_length);

                    space_list_subtract(c, false, c->offset + off_start, off_end - off_start, NULL);
                }
            }
        }

        i++;
    }
}

uint64_t chunk_estimate_phys_size(device_extension* Vcb, chunk* c, uint64_t u) {
    uint64_t nfactor, dfactor;

    if (c->chunk_item->type & BLOCK_FLAG_DUPLICATE || c->chunk_item->type & BLOCK_FLAG_RAID1 || c->chunk_item->type & BLOCK_FLAG_RAID10) {
        nfactor = 1;
        dfactor = 2;
    } else if (c->chunk_item->type & BLOCK_FLAG_RAID5) {
        nfactor = Vcb->superblock.num_devices - 1;
        dfactor = Vcb->superblock.num_devices;
    } else if (c->chunk_item->type & BLOCK_FLAG_RAID6) {
        nfactor = Vcb->superblock.num_devices - 2;
        dfactor = Vcb->superblock.num_devices;
    } else {
        nfactor = 1;
        dfactor = 1;
    }

    return u * dfactor / nfactor;
}

NTSTATUS find_chunk_usage(_In_ _Requires_lock_held_(_Curr_->tree_lock) device_extension* Vcb, _In_opt_ PIRP Irp) {
    LIST_ENTRY* le = Vcb->chunks.Flink;
    chunk* c;
    KEY searchkey;
    traverse_ptr tp;
    BLOCK_GROUP_ITEM* bgi;
    NTSTATUS Status;

    searchkey.obj_type = TYPE_BLOCK_GROUP_ITEM;

    Vcb->superblock.bytes_used = 0;

    while (le != &Vcb->chunks) {
        c = CONTAINING_RECORD(le, chunk, list_entry);

        searchkey.obj_id = c->offset;
        searchkey.offset = c->chunk_item->size;

        Status = find_item(Vcb, Vcb->extent_root, &tp, &searchkey, false, Irp);
        if (!NT_SUCCESS(Status)) {
            ERR("error - find_item returned %08x\n", Status);
            return Status;
        }

        if (!keycmp(searchkey, tp.item->key)) {
            if (tp.item->size >= sizeof(BLOCK_GROUP_ITEM)) {
                bgi = (BLOCK_GROUP_ITEM*)tp.item->data;

                c->used = c->oldused = bgi->used;

                TRACE("chunk %I64x has %I64x bytes used\n", c->offset, c->used);

                Vcb->superblock.bytes_used += chunk_estimate_phys_size(Vcb, c, bgi->used);
            } else {
                ERR("(%I64x;%I64x,%x,%I64x) is %u bytes, expected %u\n",
                    Vcb->extent_root->id, tp.item->key.obj_id, tp.item->key.obj_type, tp.item->key.offset, tp.item->size, sizeof(BLOCK_GROUP_ITEM));
            }
        }

        le = le->Flink;
    }

    Vcb->chunk_usage_found = true;

    return STATUS_SUCCESS;
}

static NTSTATUS load_sys_chunks(_In_ device_extension* Vcb) {
    KEY key;
    ULONG n = Vcb->superblock.n;

    while (n > 0) {
        if (n > sizeof(KEY)) {
            RtlCopyMemory(&key, &Vcb->superblock.sys_chunk_array[Vcb->superblock.n - n], sizeof(KEY));
            n -= sizeof(KEY);
        } else
            return STATUS_SUCCESS;

        TRACE("bootstrap: %I64x,%x,%I64x\n", key.obj_id, key.obj_type, key.offset);

        if (key.obj_type == TYPE_CHUNK_ITEM) {
            CHUNK_ITEM* ci;
            USHORT cisize;
            sys_chunk* sc;

            if (n < sizeof(CHUNK_ITEM))
                return STATUS_SUCCESS;

            ci = (CHUNK_ITEM*)&Vcb->superblock.sys_chunk_array[Vcb->superblock.n - n];
            cisize = sizeof(CHUNK_ITEM) + (ci->num_stripes * sizeof(CHUNK_ITEM_STRIPE));

            if (n < cisize)
                return STATUS_SUCCESS;

            sc = ExAllocatePoolWithTag(PagedPool, sizeof(sys_chunk), ALLOC_TAG);

            if (!sc) {
                ERR("out of memory\n");
                return STATUS_INSUFFICIENT_RESOURCES;
            }

            sc->key = key;
            sc->size = cisize;
            sc->data = ExAllocatePoolWithTag(PagedPool, sc->size, ALLOC_TAG);

            if (!sc->data) {
                ERR("out of memory\n");
                ExFreePool(sc);
                return STATUS_INSUFFICIENT_RESOURCES;
            }

            RtlCopyMemory(sc->data, ci, sc->size);
            InsertTailList(&Vcb->sys_chunks, &sc->list_entry);

            n -= cisize;
        } else {
            ERR("unexpected item %I64x,%x,%I64x in bootstrap\n", key.obj_id, key.obj_type, key.offset);
            return STATUS_INTERNAL_ERROR;
        }
    }

    return STATUS_SUCCESS;
}

_Ret_maybenull_
root* find_default_subvol(_In_ _Requires_lock_held_(_Curr_->tree_lock) device_extension* Vcb, _In_opt_ PIRP Irp) {
    LIST_ENTRY* le;

    static const char fn[] = "default";
    static uint32_t crc32 = 0x8dbfc2d2;

    if (Vcb->options.subvol_id != 0) {
        le = Vcb->roots.Flink;
        while (le != &Vcb->roots) {
            root* r = CONTAINING_RECORD(le, root, list_entry);

            if (r->id == Vcb->options.subvol_id)
                return r;

            le = le->Flink;
        }
    }

    if (Vcb->superblock.incompat_flags & BTRFS_INCOMPAT_FLAGS_DEFAULT_SUBVOL) {
        NTSTATUS Status;
        KEY searchkey;
        traverse_ptr tp;
        DIR_ITEM* di;

        searchkey.