// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
 *
 */

#include <linux/blkdev.h>
#include <linux/fs.h>
#include <linux/random.h>
#include <linux/slab.h>

#include "debug.h"
#include "ntfs.h"
#include "ntfs_fs.h"

/*
 * LOG FILE structs
 */

// clang-format off

#define MaxLogFileSize     0x100000000ull
#define DefaultLogPageSize 4096
#define MinLogRecordPages  0x30

struct RESTART_HDR {
        struct NTFS_RECORD_HEADER rhdr; // 'RSTR'
        __le32 sys_page_size; // 0x10: Page size of the system which initialized the log.
        __le32 page_size;     // 0x14: Log page size used for this log file.
        __le16 ra_off;        // 0x18:
        __le16 minor_ver;     // 0x1A:
        __le16 major_ver;     // 0x1C:
        __le16 fixups[];
};

#define LFS_NO_CLIENT 0xffff
#define LFS_NO_CLIENT_LE cpu_to_le16(0xffff)

struct CLIENT_REC {
        __le64 oldest_lsn;
        __le64 restart_lsn; // 0x08:
        __le16 prev_client; // 0x10:
        __le16 next_client; // 0x12:
        __le16 seq_num;     // 0x14:
        u8 align[6];        // 0x16:
        __le32 name_bytes;  // 0x1C: In bytes.
        __le16 name[32];    // 0x20: Name of client.
};

static_assert(sizeof(struct CLIENT_REC) == 0x60);

/* Two copies of these will exist at the beginning of the log file */
struct RESTART_AREA {
        __le64 current_lsn;    // 0x00: Current logical end of log file.
        __le16 log_clients;    // 0x08: Maximum number of clients.
        __le16 client_idx[2];  // 0x0A: Free/use index into the client record arrays.
        __le16 flags;          // 0x0E: See RESTART_SINGLE_PAGE_IO.
        __le32 seq_num_bits;   // 0x10: The number of bits in sequence number.
        __le16 ra_len;         // 0x14:
        __le16 client_off;     // 0x16:
        __le64 l_size;         // 0x18: Usable log file size.
        __le32 last_lsn_data_len; // 0x20:
        __le16 rec_hdr_len;    // 0x24: Log page data offset.
        __le16 data_off;       // 0x26: Log page data length.
        __le32 open_log_count; // 0x28:
        __le32 align[5];       // 0x2C:
        struct CLIENT_REC clients[]; // 0x40:
};

struct LOG_REC_HDR {
        __le16 redo_op;      // 0x00:  NTFS_LOG_OPERATION
        __le16 undo_op;      // 0x02:  NTFS_LOG_OPERATION
        __le16 redo_off;     // 0x04:  Offset to Redo record.
        __le16 redo_len;     // 0x06:  Redo length.
        __le16 undo_off;     // 0x08:  Offset to Undo record.
        __le16 undo_len;     // 0x0A:  Undo length.
        __le16 target_attr;  // 0x0C:
        __le16 lcns_follow;  // 0x0E:
        __le16 record_off;   // 0x10:
        __le16 attr_off;     // 0x12:
        __le16 cluster_off;  // 0x14:
        __le16 reserved;     // 0x16:
        __le64 target_vcn;   // 0x18:
        __le64 page_lcns[];  // 0x20:
};

static_assert(sizeof(struct LOG_REC_HDR) == 0x20);

#define RESTART_ENTRY_ALLOCATED    0xFFFFFFFF
#define RESTART_ENTRY_ALLOCATED_LE cpu_to_le32(0xFFFFFFFF)

struct RESTART_TABLE {
        __le16 size;       // 0x00: In bytes
        __le16 used;       // 0x02: Entries
        __le16 total;      // 0x04: Entries
        __le16 res[3];     // 0x06:
        __le32 free_goal;  // 0x0C:
        __le32 first_free; // 0x10:
        __le32 last_free;  // 0x14:

};

static_assert(sizeof(struct RESTART_TABLE) == 0x18);

struct ATTR_NAME_ENTRY {
        __le16 off; // Offset in the Open attribute Table.
        __le16 name_bytes;
        __le16 name[];
};

struct OPEN_ATTR_ENRTY {
        __le32 next;            // 0x00: RESTART_ENTRY_ALLOCATED if allocated
        __le32 bytes_per_index; // 0x04:
        enum ATTR_TYPE type;    // 0x08:
        u8 is_dirty_pages;      // 0x0C:
        u8 is_attr_name;        // 0x0B: Faked field to manage 'ptr'
        u8 name_len;            // 0x0C: Faked field to manage 'ptr'
        u8 res;
        struct MFT_REF ref;     // 0x10: File Reference of file containing attribute
        __le64 open_record_lsn; // 0x18:
        void *ptr;              // 0x20:
};

/* 32 bit version of 'struct OPEN_ATTR_ENRTY' */
struct OPEN_ATTR_ENRTY_32 {
        __le32 next;            // 0x00: RESTART_ENTRY_ALLOCATED if allocated
        __le32 ptr;             // 0x04:
        struct MFT_REF ref;     // 0x08:
        __le64 open_record_lsn; // 0x10:
        u8 is_dirty_pages;      // 0x18:
        u8 is_attr_name;        // 0x19:
        u8 res1[2];
        enum ATTR_TYPE type;    // 0x1C:
        u8 name_len;            // 0x20: In wchar
        u8 res2[3];
        __le32 AttributeName;   // 0x24:
        __le32 bytes_per_index; // 0x28:
};

#define SIZEOF_OPENATTRIBUTEENTRY0 0x2c
// static_assert( 0x2C == sizeof(struct OPEN_ATTR_ENRTY_32) );
static_assert(sizeof(struct OPEN_ATTR_ENRTY) < SIZEOF_OPENATTRIBUTEENTRY0);

/*
 * One entry exists in the Dirty Pages Table for each page which is dirty at
 * the time the Restart Area is written.
 */
struct DIR_PAGE_ENTRY {
        __le32 next;         // 0x00: RESTART_ENTRY_ALLOCATED if allocated
        __le32 target_attr;  // 0x04: Index into the Open attribute Table
        __le32 transfer_len; // 0x08:
        __le32 lcns_follow;  // 0x0C:
        __le64 vcn;          // 0x10: Vcn of dirty page
        __le64 oldest_lsn;   // 0x18:
        __le64 page_lcns[];  // 0x20:
};

static_assert(sizeof(struct DIR_PAGE_ENTRY) == 0x20);

/* 32 bit version of 'struct DIR_PAGE_ENTRY' */
struct DIR_PAGE_ENTRY_32 {
        __le32 next;            // 0x00: RESTART_ENTRY_ALLOCATED if allocated
        __le32 target_attr;     // 0x04: Index into the Open attribute Table
        __le32 transfer_len;    // 0x08:
        __le32 lcns_follow;     // 0x0C:
        __le32 reserved;        // 0x10:
        __le32 vcn_low;         // 0x14: Vcn of dirty page
        __le32 vcn_hi;          // 0x18: Vcn of dirty page
        __le32 oldest_lsn_low;  // 0x1C:
        __le32 oldest_lsn_hi;   // 0x1C:
        __le32 page_lcns_low;   // 0x24:
        __le32 page_lcns_hi;    // 0x24:
};

static_assert(offsetof(struct DIR_PAGE_ENTRY_32, vcn_low) == 0x14);
static_assert(sizeof(struct DIR_PAGE_ENTRY_32) == 0x2c);

enum transact_state {
        TransactionUninitialized = 0,
        TransactionActive,
        TransactionPrepared,
        TransactionCommitted
};

struct TRANSACTION_ENTRY {
        __le32 next;          // 0x00: RESTART_ENTRY_ALLOCATED if allocated
        u8 transact_state;    // 0x04:
        u8 reserved[3];       // 0x05:
        __le64 first_lsn;     // 0x08:
        __le64 prev_lsn;      // 0x10:
        __le64 undo_next_lsn; // 0x18:
        __le32 undo_records;  // 0x20: Number of undo log records pending abort
        __le32 undo_len;      // 0x24: Total undo size
};

static_assert(sizeof(struct TRANSACTION_ENTRY) == 0x28);

struct NTFS_RESTART {
        __le32 major_ver;             // 0x00:
        __le32 minor_ver;             // 0x04:
        __le64 check_point_start;     // 0x08:
        __le64 open_attr_table_lsn;   // 0x10:
        __le64 attr_names_lsn;        // 0x18:
        __le64 dirty_pages_table_lsn; // 0x20:
        __le64 transact_table_lsn;    // 0x28:
        __le32 open_attr_len;         // 0x30: In bytes
        __le32 attr_names_len;        // 0x34: In bytes
        __le32 dirty_pages_len;       // 0x38: In bytes
        __le32 transact_table_len;    // 0x3C: In bytes
};

static_assert(sizeof(struct NTFS_RESTART) == 0x40);

struct NEW_ATTRIBUTE_SIZES {
        __le64 alloc_size;
        __le64 valid_size;
        __le64 data_size;
        __le64 total_size;
};

struct BITMAP_RANGE {
        __le32 bitmap_off;
        __le32 bits;
};

struct LCN_RANGE {
        __le64 lcn;
        __le64 len;
};

/* The following type defines the different log record types. */
#define LfsClientRecord  cpu_to_le32(1)
#define LfsClientRestart cpu_to_le32(2)

/* This is used to uniquely identify a client for a particular log file. */
struct CLIENT_ID {
        __le16 seq_num;
        __le16 client_idx;
};

/* This is the header that begins every Log Record in the log file. */
struct LFS_RECORD_HDR {
        __le64 this_lsn;                // 0x00:
        __le64 client_prev_lsn;         // 0x08:
        __le64 client_undo_next_lsn;    // 0x10:
        __le32 client_data_len;         // 0x18:
        struct CLIENT_ID client;        // 0x1C: Owner of this log record.
        __le32 record_type;             // 0x20: LfsClientRecord or LfsClientRestart.
        __le32 transact_id;             // 0x24:
        __le16 flags;                   // 0x28: LOG_RECORD_MULTI_PAGE
        u8 align[6];                    // 0x2A:
};

#define LOG_RECORD_MULTI_PAGE cpu_to_le16(1)

static_assert(sizeof(struct LFS_RECORD_HDR) == 0x30);

struct LFS_RECORD {
        __le16 next_record_off; // 0x00: Offset of the free space in the page,
        u8 align[6];            // 0x02:
        __le64 last_end_lsn;    // 0x08: lsn for the last log record which ends on the page,
};

static_assert(sizeof(struct LFS_RECORD) == 0x10);

struct RECORD_PAGE_HDR {
        struct NTFS_RECORD_HEADER rhdr; // 'RCRD'
        __le32 rflags;                  // 0x10: See LOG_PAGE_LOG_RECORD_END
        __le16 page_count;              // 0x14:
        __le16 page_pos;                // 0x16:
        struct LFS_RECORD record_hdr;   // 0x18:
        __le16 fixups[10];              // 0x28:
        __le32 file_off;                // 0x3c: Used when major version >= 2
};

// clang-format on

// Page contains the end of a log record.
#define LOG_PAGE_LOG_RECORD_END cpu_to_le32(0x00000001)

static inline bool is_log_record_end(const struct RECORD_PAGE_HDR *hdr)
{
        return hdr->rflags & LOG_PAGE_LOG_RECORD_END;
}

static_assert(offsetof(struct RECORD_PAGE_HDR, file_off) == 0x3c);

/*
 * END of NTFS LOG structures
 */

/* Define some tuning parameters to keep the restart tables a reasonable size. */
#define INITIAL_NUMBER_TRANSACTIONS 5

enum NTFS_LOG_OPERATION {

        Noop = 0x00,
        CompensationLogRecord = 0x01,
        InitializeFileRecordSegment = 0x02,
        DeallocateFileRecordSegment = 0x03,
        WriteEndOfFileRecordSegment = 0x04,
        CreateAttribute = 0x05,
        DeleteAttribute = 0x06,
        UpdateResidentValue = 0x07,
        UpdateNonresidentValue = 0x08,
        UpdateMappingPairs = 0x09,
        DeleteDirtyClusters = 0x0A,
        SetNewAttributeSizes = 0x0B,
        AddIndexEntryRoot = 0x0C,
        DeleteIndexEntryRoot = 0x0D,
        AddIndexEntryAllocation = 0x0E,
        DeleteIndexEntryAllocation = 0x0F,
        WriteEndOfIndexBuffer = 0x10,
        SetIndexEntryVcnRoot = 0x11,
        SetIndexEntryVcnAllocation = 0x12,
        UpdateFileNameRoot = 0x13,
        UpdateFileNameAllocation = 0x14,
        SetBitsInNonresidentBitMap = 0x15,
        ClearBitsInNonresidentBitMap = 0x16,
        HotFix = 0x17,
        EndTopLevelAction = 0x18,
        PrepareTransaction = 0x19,
        CommitTransaction = 0x1A,
        ForgetTransaction = 0x1B,
        OpenNonresidentAttribute = 0x1C,
        OpenAttributeTableDump = 0x1D,
        AttributeNamesDump = 0x1E,
        DirtyPageTableDump = 0x1F,
        TransactionTableDump = 0x20,
        UpdateRecordDataRoot = 0x21,
        UpdateRecordDataAllocation = 0x22,

        UpdateRelativeDataInIndex =
                0x23, // NtOfsRestartUpdateRelativeDataInIndex
        UpdateRelativeDataInIndex2 = 0x24,
        ZeroEndOfFileRecord = 0x25,
};

/*
 * Array for log records which require a target attribute.
 * A true indicates that the corresponding restart operation
 * requires a target attribute.
 */
static const u8 AttributeRequired[] = {
        0xFC, 0xFB, 0xFF, 0x10, 0x06,
};

static inline bool is_target_required(u16 op)
{
        bool ret = op <= UpdateRecordDataAllocation &&
                   (AttributeRequired[op >> 3] >> (op & 7) & 1);
        return ret;
}

static inline bool can_skip_action(enum NTFS_LOG_OPERATION op)
{
        switch (op) {
        case Noop:
        case DeleteDirtyClusters:
        case HotFix:
        case EndTopLevelAction:
        case PrepareTransaction:
        case CommitTransaction:
        case ForgetTransaction:
        case CompensationLogRecord:
        case OpenNonresidentAttribute:
        case OpenAttributeTableDump:
        case AttributeNamesDump:
        case DirtyPageTableDump:
        case TransactionTableDump:
                return true;
        default:
                return false;
        }
}

enum { lcb_ctx_undo_next, lcb_ctx_prev, lcb_ctx_next };

/* Bytes per restart table. */
static inline u32 bytes_per_rt(const struct RESTART_TABLE *rt)
{
        return le16_to_cpu(rt->used) * le16_to_cpu(rt->size) +
               sizeof(struct RESTART_TABLE);
}

/* Log record length. */
static inline u32 lrh_length(const struct LOG_REC_HDR *lr)
{
        u16 t16 = le16_to_cpu(lr->lcns_follow);

        return struct_size(lr, page_lcns, max_t(u16, 1, t16));
}

struct lcb {
        struct LFS_RECORD_HDR *lrh; // Log record header of the current lsn.
        struct LOG_REC_HDR *log_rec;
        u32 ctx_mode; // lcb_ctx_undo_next/lcb_ctx_prev/lcb_ctx_next
        struct CLIENT_ID client;
        bool alloc; // If true the we should deallocate 'log_rec'.
};

static void lcb_put(struct lcb *lcb)
{
        if (lcb->alloc)
                kfree(lcb->log_rec);
        kfree(lcb->lrh);
        kfree(lcb);
}

/* Find the oldest lsn from active clients. */
static inline void oldest_client_lsn(const struct CLIENT_REC *ca,
                                     __le16 next_client, u64 *oldest_lsn)
{
        while (next_client != LFS_NO_CLIENT_LE) {
                const struct CLIENT_REC *cr = ca + le16_to_cpu(next_client);
                u64 lsn = le64_to_cpu(cr->oldest_lsn);

                /* Ignore this block if it's oldest lsn is 0. */
                if (lsn && lsn < *oldest_lsn)
                        *oldest_lsn = lsn;

                next_client = cr->next_client;
        }
}

static inline bool is_rst_page_hdr_valid(u32 file_off,
                                         const struct RESTART_HDR *rhdr)
{
        u32 sys_page = le32_to_cpu(rhdr->sys_page_size);
        u32 page_size = le32_to_cpu(rhdr->page_size);
        u32 end_usa;
        u16 ro;

        if (sys_page < SECTOR_SIZE || page_size < SECTOR_SIZE ||
            sys_page & (sys_page - 1) || page_size & (page_size - 1)) {
                return false;
        }

        /* Check that if the file offset isn't 0, it is the system page size. */
        if (file_off && file_off != sys_page)
                return false;

        /* Check support version 1.1+. */
        if (le16_to_cpu(rhdr->major_ver) <= 1 && !rhdr->minor_ver)
                return false;

        if (le16_to_cpu(rhdr->major_ver) > 2)
                return false;

        ro = le16_to_cpu(rhdr->ra_off);
        if (!IS_ALIGNED(ro, 8) || ro > sys_page)
                return false;

        end_usa = ((sys_page >> SECTOR_SHIFT) + 1) * sizeof(short);
        end_usa += le16_to_cpu(rhdr->rhdr.fix_off);

        if (ro < end_usa)
                return false;

        return true;
}

static inline bool is_rst_area_valid(const struct RESTART_HDR *rhdr)
{
        const struct RESTART_AREA *ra;
        u16 cl, fl, ul;
        u32 off, l_size, file_dat_bits, file_size_round;
        u16 ro = le16_to_cpu(rhdr->ra_off);
        u32 sys_page = le32_to_cpu(rhdr->sys_page_size);

        if (ro + offsetof(struct RESTART_AREA, l_size) >
            SECTOR_SIZE - sizeof(short))
                return false;

        ra = Add2Ptr(rhdr, ro);
        cl = le16_to_cpu(ra->log_clients);

        if (cl > 1)
                return false;

        off = le16_to_cpu(ra->client_off);

        if (!IS_ALIGNED(off, 8) || ro + off > SECTOR_SIZE - sizeof(short))
                return false;

        off += cl * sizeof(struct CLIENT_REC);

        if (off > sys_page)
                return false;

        /*
         * Check the restart length field and whether the entire
         * restart area is contained that length.
         */
        if (le16_to_cpu(rhdr->ra_off) + le16_to_cpu(ra->ra_len) > sys_page ||
            off > le16_to_cpu(ra->ra_len)) {
                return false;
        }

        /*
         * As a final check make sure that the use list and the free list
         * are either empty or point to a valid client.
         */
        fl = le16_to_cpu(ra->client_idx[0]);
        ul = le16_to_cpu(ra->client_idx[1]);
        if ((fl != LFS_NO_CLIENT && fl >= cl) ||
            (ul != LFS_NO_CLIENT && ul >= cl))
                return false;

        /* Make sure the sequence number bits match the log file size. */
        l_size = le64_to_cpu(ra->l_size);

        file_dat_bits = sizeof(u64) * 8 - le32_to_cpu(ra->seq_num_bits);
        file_size_round = 1u << (file_dat_bits + 3);
        if (file_size_round != l_size &&
            (file_size_round < l_size || (file_size_round / 2) > l_size)) {
                return false;
        }

        /* The log page data offset and record header length must be quad-aligned. */
        if (!IS_ALIGNED(le16_to_cpu(ra->data_off), 8) ||
            !IS_ALIGNED(le16_to_cpu(ra->rec_hdr_len), 8))
                return false;

        return true;
}

static inline bool is_client_area_valid(const struct RESTART_HDR *rhdr,
                                        bool usa_error)
{
        u16 ro = le16_to_cpu(rhdr->ra_off);
        const struct RESTART_AREA *ra = Add2Ptr(rhdr, ro);
        u16 ra_len = le16_to_cpu(ra->ra_len);
        const struct CLIENT_REC *ca;
        u32 i;

        if (usa_error && ra_len + ro > SECTOR_SIZE - sizeof(short))
                return false;

        /* Find the start of the client array. */
        ca = Add2Ptr(ra, le16_to_cpu(ra->client_off));

        /*
         * Start with the free list.
         * Check that all the clients are valid and that there isn't a cycle.
         * Do the in-use list on the second pass.
         */
        for (i = 0; i < 2; i++) {
                u16 client_idx = le16_to_cpu(ra->client_idx[i]);
                bool first_client = true;
                u16 clients = le16_to_cpu(ra->log_clients);

                while (client_idx != LFS_NO_CLIENT) {
                        const struct CLIENT_REC *cr;

                        if (!clients ||
                            client_idx >= le16_to_cpu(ra->log_clients))
                                return false;

                        clients -= 1;
                        cr = ca + client_idx;

                        client_idx = le16_to_cpu(cr->next_client);

                        if (first_client) {
                                first_client = false;
                                if (cr->prev_client != LFS_NO_CLIENT_LE)
                                        return false;
                        }
                }
        }

        return true;
}

/*
 * remove_client
 *
 * Remove a client record from a client record list an restart area.
 */
static inline void remove_client(struct CLIENT_REC *ca,
                                 const struct CLIENT_REC *cr, __le16 *head)
{
        if (cr->prev_client == LFS_NO_CLIENT_LE)
                *head = cr->next_client;
        else
                ca[le16_to_cpu(cr->prev_client)].next_client = cr->next_client;

        if (cr->next_client != LFS_NO_CLIENT_LE)
                ca[le16_to_cpu(cr->next_client)].prev_client = cr->prev_client;
}

/*
 * add_client - Add a client record to the start of a list.
 */
static inline void add_client(struct CLIENT_REC *ca, u16 index, __le16 *head)
{
        struct CLIENT_REC *cr = ca + index;

        cr->prev_client = LFS_NO_CLIENT_LE;
        cr->next_client = *head;

        if (*head != LFS_NO_CLIENT_LE)
                ca[le16_to_cpu(*head)].prev_client = cpu_to_le16(index);

        *head = cpu_to_le16(index);
}

static inline void *enum_rstbl(struct RESTART_TABLE *t, void *c)
{
        __le32 *e;
        u32 bprt;
        u16 rsize = t ? le16_to_cpu(t->size) : 0;

        if (!c) {
                if (!t || !t->total)
                        return NULL;
                e = Add2Ptr(t, sizeof(struct RESTART_TABLE));
        } else {
                e = Add2Ptr(c, rsize);
        }

        /* Loop until we hit the first one allocated, or the end of the list. */
        for (bprt = bytes_per_rt(t); PtrOffset(t, e) < bprt;
             e = Add2Ptr(e, rsize)) {
                if (*e == RESTART_ENTRY_ALLOCATED_LE)
                        return e;
        }
        return NULL;
}

/*
 * find_dp - Search for a @vcn in Dirty Page Table.
 */
static inline struct DIR_PAGE_ENTRY *find_dp(struct RESTART_TABLE *dptbl,
                                             u32 target_attr, u64 vcn)
{
        __le32 ta = cpu_to_le32(target_attr);
        struct DIR_PAGE_ENTRY *dp = NULL;

        while ((dp = enum_rstbl(dptbl, dp))) {
                u64 dp_vcn = le64_to_cpu(dp->vcn);

                if (dp->target_attr == ta && vcn >= dp_vcn &&
                    vcn < dp_vcn + le32_to_cpu(dp->lcns_follow)) {
                        return dp;
                }
        }
        return NULL;
}

static inline u32 norm_file_page(u32 page_size, u32 *l_size, bool use_default)
{
        if (use_default)
                page_size = DefaultLogPageSize;

        /* Round the file size down to a system page boundary. */
        *l_size &= ~(page_size - 1);

        /* File should contain at least 2 restart pages and MinLogRecordPages pages. */
        if (*l_size < (MinLogRecordPages + 2) * page_size)
                return 0;

        return page_size;
}

static bool check_log_rec(const struct LOG_REC_HDR *lr, u32 bytes, u32 tr,
                          u32 bytes_per_attr_entry)
{
        u16 t16;

        if (bytes < sizeof(struct LOG_REC_HDR))
                return false;
        if (!tr)
                return false;

        if ((tr - sizeof(struct RESTART_TABLE)) %
            sizeof(struct TRANSACTION_ENTRY))
                return false;

        if (le16_to_cpu(lr->redo_off) & 7)
                return false;

        if (le16_to_cpu(lr->undo_off) & 7)
                return false;

        if (lr->target_attr)
                goto check_lcns;

        if (is_target_required(le16_to_cpu(lr->redo_op)))
                return false;

        if (is_target_required(le16_to_cpu(lr->undo_op)))
                return false;

check_lcns:
        if (!lr->lcns_follow)
                goto check_length;

        t16 = le16_to_cpu(lr->target_attr);
        if ((t16 - sizeof(struct RESTART_TABLE)) % bytes_per_attr_entry)
                return false;

check_length:
        if (bytes < lrh_length(lr))
                return false;

        return true;
}

static bool check_rstbl(const struct RESTART_TABLE *rt, size_t bytes)
{
        u32 ts;
        u32 i, off;
        u16 rsize = le16_to_cpu(rt->size);
        u16 ne = le16_to_cpu(rt->used);
        u32 ff = le32_to_cpu(rt->first_free);
        u32 lf = le32_to_cpu(rt->last_free);

        ts = rsize * ne + sizeof(struct RESTART_TABLE);

        if (!rsize || rsize > bytes ||
            rsize + sizeof(struct RESTART_TABLE) > bytes || bytes < ts ||
            le16_to_cpu(rt->total) > ne || ff > ts || lf > ts ||
            (ff && ff < sizeof(struct RESTART_TABLE)) ||
            (lf && lf < sizeof(struct RESTART_TABLE))) {
                return false;
        }

        /*
         * Verify each entry is either allocated or points
         * to a valid offset the table.
         */
        for (i = 0; i < ne; i++) {
                off = le32_to_cpu(*(__le32 *)Add2Ptr(
                        rt, i * rsize + sizeof(struct RESTART_TABLE)));

                if (off != RESTART_ENTRY_ALLOCATED && off &&
                    (off < sizeof(struct RESTART_TABLE) ||
                     ((off - sizeof(struct RESTART_TABLE)) % rsize))) {
                        return false;
                }
        }

        /*
         * Walk through the list headed by the first entry to make
         * sure none of the entries are currently being used.
         */
        for (off = ff; off;) {
                if (off == RESTART_ENTRY_ALLOCATED)
                        return false;

                off = le32_to_cpu(*(__le32 *)Add2Ptr(rt, off));
        }

        return true;
}

/*
 * free_rsttbl_idx - Free a previously allocated index a Restart Table.
 */
static inline void free_rsttbl_idx(struct RESTART_TABLE *rt, u32 off)
{
        __le32 *e;
        u32 lf = le32_to_cpu(rt->last_free);
        __le32 off_le = cpu_to_le32(off);

        e = Add2Ptr(rt, off);

        if (off < le32_to_cpu(rt->free_goal)) {
                *e = rt->first_free;
                rt->first_free = off_le;
                if (!lf)
                        rt->last_free = off_le;
        } else {
                if (lf)
                        *(__le32 *)Add2Ptr(rt, lf) = off_le;
                else
                        rt->first_free = off_le;

                rt->last_free = off_le;
                *e = 0;
        }

        le16_sub_cpu(&rt->total, 1);
}

static inline struct RESTART_TABLE *init_rsttbl(u16 esize, u16 used)
{
        __le32 *e, *last_free;
        u32 off;
        u32 bytes = esize * used + sizeof(struct RESTART_TABLE);
        u32 lf = sizeof(struct RESTART_TABLE) + (used - 1) * esize;
        struct RESTART_TABLE *t = kzalloc(bytes, GFP_NOFS);

        if (!t)
                return NULL;

        t->size = cpu_to_le16(esize);
        t->used = cpu_to_le16(used);
        t->free_goal = cpu_to_le32(~0u);
        t->first_free = cpu_to_le32(sizeof(struct RESTART_TABLE));
        t->last_free = cpu_to_le32(lf);

        e = (__le32 *)(t + 1);
        last_free = Add2Ptr(t, lf);

        for (off = sizeof(struct RESTART_TABLE) + esize; e < last_free;
             e = Add2Ptr(e, esize), off += esize) {
                *e = cpu_to_le32(off);
        }
        return t;
}

static inline struct RESTART_TABLE *extend_rsttbl(struct RESTART_TABLE *tbl,
                                                  u32 add, u32 free_goal)
{
        u16 esize = le16_to_cpu(tbl->size);
        __le32 osize = cpu_to_le32(bytes_per_rt(tbl));
        u32 used = le16_to_cpu(tbl->used);
        struct RESTART_TABLE *rt;

        rt = init_rsttbl(esize, used + add);
        if (!rt)
                return NULL;

        memcpy(rt + 1, tbl + 1, esize * used);

        rt->free_goal = free_goal == ~0u
                                ? cpu_to_le32(~0u)
                                : cpu_to_le32(sizeof(struct RESTART_TABLE) +
                                              free_goal * esize);

        if (tbl->first_free) {
                rt->first_free = tbl->first_free;
                *(__le32 *)Add2Ptr(rt, le32_to_cpu(tbl->last_free)) = osize;
        } else {
                rt->first_free = osize;
        }

        rt->total = tbl->total;

        kfree(tbl);
        return rt;
}

/*
 * alloc_rsttbl_idx
 *
 * Allocate an index from within a previously initialized Restart Table.
 */
static inline void *alloc_rsttbl_idx(struct RESTART_TABLE **tbl)
{
        u32 off;
        __le32 *e;
        struct RESTART_TABLE *t = *tbl;

        if (!t->first_free) {
                *tbl = t = extend_rsttbl(t, 16, ~0u);
                if (!t)
                        return NULL;
        }

        off = le32_to_cpu(t->first_free);

        /* Dequeue this entry and zero it. */
        e = Add2Ptr(t, off);

        t->first_free = *e;

        memset(e, 0, le16_to_cpu(t->size));

        *e = RESTART_ENTRY_ALLOCATED_LE;

        /* If list is going empty, then we fix the last_free as well. */
        if (!t->first_free)
                t->last_free = 0;

        le16_add_cpu(&t->total, 1);

        return Add2Ptr(t, off);
}

/*
 * alloc_rsttbl_from_idx
 *
 * Allocate a specific index from within a previously initialized Restart Table.
 */
static inline void *alloc_rsttbl_from_idx(struct RESTART_TABLE **tbl, u32 vbo)
{
        u32 off;
        __le32 *e;
        struct RESTART_TABLE *rt = *tbl;
        u32 bytes = bytes_per_rt(rt);
        u16 esize = le16_to_cpu(rt->size);

        /* If the entry is not the table, we will have to extend the table. */
        if (vbo >= bytes) {
                /*
                 * Extend the size by computing the number of entries between
                 * the existing size and the desired index and adding 1 to that.
                 */
                u32 bytes2idx = vbo - bytes;

                /*
                 * There should always be an integral number of entries
                 * being added. Now extend the table.
                 */
                *tbl = rt = extend_rsttbl(rt, bytes2idx / esize + 1, bytes);
                if (!rt)
                        return NULL;
        }

        /* See if the entry is already allocated, and just return if it is. */
        e = Add2Ptr(rt, vbo);

        if (*e == RESTART_ENTRY_ALLOCATED_LE)
                return e;

        /*
         * Walk through the table, looking for the entry we're
         * interested and the previous entry.
         */
        off = le32_to_cpu(rt->first_free);
        e = Add2Ptr(rt, off);

        if (off == vbo) {
                /* this is a match */
                rt->first_free = *e;
                goto skip_looking;
        }

        /*
         * Need to walk through the list looking for the predecessor
         * of our entry.
         */
        for (;;) {
                /* Remember the entry just found */
                u32 last_off = off;
                __le32 *last_e = e;

                /* Should never run of entries. */

                /* Lookup up the next entry the list. */
                off = le32_to_cpu(*last_e);
                e = Add2Ptr(rt, off);

                /* If this is our match we are done. */
                if (off == vbo) {
                        *last_e = *e;

                        /*
                         * If this was the last entry, we update that
                         * table as well.
                         */
                        if (le32_to_cpu(rt->last_free) == off)
                                rt->last_free = cpu_to_le32(last_off);
                        break;
                }
        }

skip_looking:
        /* If the list is now empty, we fix the last_free as well. */
        if (!rt->first_free)
                rt->last_free = 0;

        /* Zero this entry. */
        memset(e, 0, esize);
        *e = RESTART_ENTRY_ALLOCATED_LE;

        le16_add_cpu(&rt->total, 1);

        return e;
}

#define RESTART_SINGLE_PAGE_IO cpu_to_le16(0x0001)

#define NTFSLOG_WRAPPED 0x00000001
#define NTFSLOG_MULTIPLE_PAGE_IO 0x00000002
#define NTFSLOG_NO_LAST_LSN 0x00000004
#define NTFSLOG_REUSE_TAIL 0x00000010
#define NTFSLOG_NO_OLDEST_LSN 0x00000020

/* Helper struct to work with NTFS $LogFile. */
struct ntfs_log {
        struct ntfs_inode *ni;

        u32 l_size;
        u32 sys_page_size;
        u32 sys_page_mask;
        u32 page_size;
        u32 page_mask; // page_size - 1
        u8 page_bits;
        struct RECORD_PAGE_HDR *one_page_buf;

        struct RESTART_TABLE *open_attr_tbl;
        u32 transaction_id;
        u32 clst_per_page;

        u32 first_page;
        u32 next_page;
        u32 ra_off;
        u32 data_off;
        u32 restart_size;
        u32 data_size;
        u16 record_header_len;
        u64 seq_num;
        u32 seq_num_bits;
        u32 file_data_bits;
        u32 seq_num_mask; /* (1 << file_data_bits) - 1 */

        struct RESTART_AREA *ra; /* In-memory image of the next restart area. */
        u32 ra_size; /* The usable size of the restart area. */

        /*
         * If true, then the in-memory restart area is to be written
         * to the first position on the disk.
         */
        bool init_ra;
        bool set_dirty; /* True if we need to set dirty flag. */

        u64 oldest_lsn;

        u32 oldest_lsn_off;
        u64 last_lsn;

        u32 total_avail;
        u32 total_avail_pages;
        u32 total_undo_commit;
        u32 max_current_avail;
        u32 current_avail;
        u32 reserved;

        short major_ver;
        short minor_ver;

        u32 l_flags; /* See NTFSLOG_XXX */
        u32 current_openlog_count; /* On-disk value for open_log_count. */

        struct CLIENT_ID client_id;
        u32 client_undo_commit;
};

static inline u32 lsn_to_vbo(struct ntfs_log *log, const u64 lsn)
{
        u32 vbo = (lsn << log->seq_num_bits) >> (log->seq_num_bits - 3);

        return vbo;
}

/* Compute the offset in the log file of the next log page. */
static inline u32 next_page_off(struct ntfs_log *log, u32 off)
{
        off = (off & ~log->sys_page_mask) + log->page_size;
        return off >= log->l_size ? log->first_page : off;
}

static inline u32 lsn_to_page_off(struct ntfs_log *log, u64 lsn)
{
        return (((u32)lsn) << 3) & log->page_mask;
}

static inline u64 vbo_to_lsn(struct ntfs_log *log, u32 off, u64 Seq)
{
        return (off >> 3) + (Seq << log->file_data_bits);
}

static inline bool is_lsn_in_file(struct ntfs_log *log, u64 lsn)
{
        return lsn >= log->oldest_lsn &&
               lsn <= le64_to_cpu(log->ra->current_lsn);
}

static inline u32 hdr_file_off(struct ntfs_log *log,
                               struct RECORD_PAGE_HDR *hdr)
{
        if (log->major_ver < 2)
                return le64_to_cpu(hdr->rhdr.lsn);

        return le32_to_cpu(hdr->file_off);
}

static inline u64 base_lsn(struct ntfs_log *log,
                           const struct RECORD_PAGE_HDR *hdr, u64 lsn)
{
        u64 h_lsn = le64_to_cpu(hdr->rhdr.lsn);
        u64 ret = (((h_lsn >> log->file_data_bits) +
                    (lsn < (lsn_to_vbo(log, h_lsn) & ~log->page_mask) ? 1 : 0))
                   << log->file_data_bits) +
                  ((((is_log_record_end(hdr) &&
                      h_lsn <= le64_to_cpu(hdr->record_hdr.last_end_lsn))
                             ? le16_to_cpu(hdr->record_hdr.next_record_off)
                             : log->page_size) +
                    lsn) >>
                   3);

        return ret;
}

static inline bool verify_client_lsn(struct ntfs_log *log,
                                     const struct CLIENT_REC *client, u64 lsn)
{
        return lsn >= le64_to_cpu(client->oldest_lsn) &&
               lsn <= le64_to_cpu(log->ra->current_lsn) && lsn;
}

struct restart_info {
        u64 last_lsn;
        struct RESTART_HDR *r_page;
        u32 vbo;
        bool chkdsk_was_run;
        bool valid_page;
        bool initialized;
        bool restart;
};

static int read_log_page(struct ntfs_log *log, u32 vbo,
                         struct RECORD_PAGE_HDR **buffer, bool *usa_error)
{
        int err = 0;
        u32 page_idx = vbo >> log->page_bits;
        u32 page_off = vbo & log->page_mask;
        u32 bytes = log->page_size - page_off;
        void *to_free = NULL;
        u32 page_vbo = page_idx << log->page_bits;
        struct RECORD_PAGE_HDR *page_buf;
        struct ntfs_inode *ni = log->ni;
        bool bBAAD;

        if (vbo >= log->l_size)
                return -EINVAL;

        if (!*buffer) {
                to_free = kmalloc(bytes, GFP_NOFS);
                if (!to_free)
                        return -ENOMEM;
                *buffer = to_free;
        }

        page_buf = page_off ? log->one_page_buf : *buffer;

        err = ntfs_read_run_nb(ni->mi.sbi, &ni->file.run, page_vbo, page_buf,
                               log->page_size, NULL);
        if (err)
                goto out;

        if (page_buf->rhdr.sign != NTFS_FFFF_SIGNATURE)
                ntfs_fix_post_read(&page_buf->rhdr, PAGE_SIZE, false);

        if (page_buf != *buffer)
                memcpy(*buffer, Add2Ptr(page_buf, page_off), bytes);

        bBAAD = page_buf->rhdr.sign == NTFS_BAAD_SIGNATURE;

        if (usa_error)
                *usa_error = bBAAD;
        /* Check that the update sequence array for this page is valid */
        /* If we don't allow errors, raise an error status */
        else if (bBAAD)
                err = -EINVAL;

out:
        if (err && to_free) {
                kfree(to_free);
                *buffer = NULL;
        }

        return err;
}

/*
 * log_read_rst
 *
 * It walks through 512 blocks of the file looking for a valid
 * restart page header. It will stop the first time we find a
 * valid page header.
 */
static int log_read_rst(struct ntfs_log *log, u32 l_size, bool first,
                        struct restart_info *info)
{
        u32 skip, vbo;
        struct RESTART_HDR *r_page = kmalloc(DefaultLogPageSize, GFP_NOFS);

        if (!r_page)
                return -ENOMEM;

        /* Determine which restart area we are looking for. */
        if (first) {
                vbo = 0;
                skip = 512;
        } else {
                vbo = 512;
                skip = 0;
        }

        /* Loop continuously until we succeed. */
        for (; vbo < l_size; vbo = 2 * vbo + skip, skip = 0) {
                bool usa_error;
                u32 sys_page_size;
                bool brst, bchk;
                struct RESTART_AREA *ra;

                /* Read a page header at the current offset. */
                if (read_log_page(log, vbo, (struct RECORD_PAGE_HDR **)&r_page,
                                  &usa_error)) {
                        /* Ignore any errors. */
                        continue;
                }

                /* Exit if the signature is a log record page. */
                if (r_page->rhdr.sign == NTFS_RCRD_SIGNATURE) {
                        info->initialized = true;
                        break;
                }

                brst = r_page->rhdr.sign == NTFS_RSTR_SIGNATURE;
                bchk = r_page->rhdr.sign == NTFS_CHKD_SIGNATURE;

                if (!bchk && !brst) {
                        if (r_page->rhdr.sign != NTFS_FFFF_SIGNATURE) {
                                /*
                                 * Remember if the signature does not
                                 * indicate uninitialized file.
                                 */
                                info->initialized = true;
                        }
                        continue;
                }

                ra = NULL;
                info->valid_page = false;
                info->initialized = true;
                info->vbo = vbo;

                /* Let's check the restart area if this is a valid page. */
                if (!is_rst_page_hdr_valid(vbo, r_page))
                        goto check_result;
                ra = Add2Ptr(r_page, le16_to_cpu(r_page->ra_off));

                if (!is_rst_area_valid(r_page))
                        goto check_result;

                /*
                 * We have a valid restart page header and restart area.
                 * If chkdsk was run or we have no clients then we have
                 * no more checking to do.
                 */
                if (bchk || ra->client_idx[1] == LFS_NO_CLIENT_LE) {
                        info->valid_page = true;
                        goto check_result;
                }

                /* Read the entire restart area. */
                sys_page_size = le32_to_cpu(r_page->sys_page_size);
                if (DefaultLogPageSize != sys_page_size) {
                        kfree(r_page);
                        r_page = kzalloc(sys_page_size, GFP_NOFS);
                        if (!r_page)
                                return -ENOMEM;

                        if (read_log_page(log, vbo,
                                          (struct RECORD_PAGE_HDR **)&r_page,
                                          &usa_error)) {
                                /* Ignore any errors. */
                                kfree(r_page);
                                r_page = NULL;
                                continue;
                        }
                }

                if (is_client_area_valid(r_page, usa_error)) {
                        info->valid_page = true;
                        ra = Add2Ptr(r_page, le16_to_cpu(r_page->ra_off));
                }

check_result:
                /*
                 * If chkdsk was run then update the caller's
                 * values and return.
                 */
                if (r_page->rhdr.sign == NTFS_CHKD_SIGNATURE) {
                        info->chkdsk_was_run = true;
                        info->last_lsn = le64_to_cpu(r_page->rhdr.lsn);
                        info->restart = true;
                        info->r_page = r_page;
                        return 0;
                }

                /*
                 * If we have a valid page then copy the values
                 * we need from it.
                 */
                if (info->valid_page) {
                        info->last_lsn = le64_to_cpu(ra->current_lsn);
                        info->restart = true;
                        info->r_page = r_page;
                        return 0;
                }
        }

        kfree(r_page);

        return 0;
}

/*
 * Ilog_init_pg_hdr - Init @log from restart page header.
 */
static void log_init_pg_hdr(struct ntfs_log *log, u32 sys_page_size,
                            u32 page_size, u16 major_ver, u16 minor_ver)
{
        log->sys_page_size = sys_page_size;
        log->sys_page_mask = sys_page_size - 1;
        log->page_size = page_size;
        log->page_mask = page_size - 1;
        log->page_bits = blksize_bits(page_size);

        log->clst_per_page = log->page_size >> log->ni->mi.sbi->cluster_bits;
        if (!log->clst_per_page)
                log->clst_per_page = 1;

        log->first_page = major_ver >= 2
                                  ? 0x22 * page_size
                                  : ((sys_page_size << 1) + (page_size << 1));
        log->major_ver = major_ver;
        log->minor_ver = minor_ver;
}

/*
 * log_create - Init @log in cases when we don't have a restart area to use.
 */
static void log_create(struct ntfs_log *log, u32 l_size, const u64 last_lsn,
                       u32 open_log_count, bool wrapped, bool use_multi_page)
{
        log->l_size = l_size;
        /* All file offsets must be quadword aligned. */
        log->file_data_bits = blksize_bits(l_size) - 3;
        log->seq_num_mask = (8 << log->file_data_bits) - 1;
        log->seq_num_bits = sizeof(u64) * 8 - log->file_data_bits;
        log->seq_num = (last_lsn >> log->file_data_bits) + 2;
        log->next_page = log->first_page;
        log->oldest_lsn = log->seq_num << log->file_data_bits;
        log->oldest_lsn_off = 0;
        log->last_lsn = log->oldest_lsn;

        log->l_flags |= NTFSLOG_NO_LAST_LSN | NTFSLOG_NO_OLDEST_LSN;

        /* Set the correct flags for the I/O and indicate if we have wrapped. */
        if (wrapped)
                log->l_flags |= NTFSLOG_WRAPPED;

        if (use_multi_page)
                log->l_flags |= NTFSLOG_MULTIPLE_PAGE_IO;

        /* Compute the log page values. */
        log->data_off = ALIGN(
                offsetof(struct RECORD_PAGE_HDR, fixups) +
                        sizeof(short) * ((log->page_size >> SECTOR_SHIFT) + 1),
                8);
        log->data_size = log->page_size - log->data_off;
        log->record_header_len = sizeof(struct LFS_RECORD_HDR);

        /* Remember the different page sizes for reservation. */
        log->reserved = log->data_size - log->record_header_len;

        /* Compute the restart page values. */
        log->ra_off = ALIGN(
                offsetof(struct RESTART_HDR, fixups) +
                        sizeof(short) *
                                ((log->sys_page_size >> SECTOR_SHIFT) + 1),
                8);
        log->restart_size = log->sys_page_size - log->ra_off;
        log->ra_size = struct_size(log->ra, clients, 1);
        log->current_openlog_count = open_log_count;

        /*
         * The total available log file space is the number of
         * log file pages times the space available on each page.
         */
        log->total_avail_pages = log->l_size - log->first_page;
        log->total_avail = log->total_avail_pages >> log->page_bits;

        /*
         * We assume that we can't use the end of the page less than
         * the file record size.
         * Then we won't need to reserve more than the caller asks for.
         */
        log->max_current_avail = log->total_avail * log->reserved;
        log->total_avail = log->total_avail * log->data_size;
        log->current_avail = log->max_current_avail;
}

/*
 * log_create_ra - Fill a restart area from the values stored in @log.
 */
static struct RESTART_AREA *log_create_ra(struct ntfs_log *log)
{
        struct CLIENT_REC *cr;
        struct RESTART_AREA *ra = kzalloc(log->restart_size, GFP_NOFS);

        if (!ra)
                return NULL;

        ra->current_lsn = cpu_to_le64(log->last_lsn);
        ra->log_clients = cpu_to_le16(1);
        ra->client_idx[1] = LFS_NO_CLIENT_LE;
        if (log->l_flags & NTFSLOG_MULTIPLE_PAGE_IO)
                ra->flags = RESTART_SINGLE_PAGE_IO;
        ra->seq_num_bits = cpu_to_le32(log->seq_num_bits);
        ra->ra_len = cpu_to_le16(log->ra_size);
        ra->client_off = cpu_to_le16(offsetof(struct RESTART_AREA, clients));
        ra->l_size = cpu_to_le64(log->l_size);
        ra->rec_hdr_len = cpu_to_le16(log->record_header_len);
        ra->data_off = cpu_to_le16(log->data_off);
        ra->open_log_count = cpu_to_le32(log->current_openlog_count + 1);

        cr = ra->clients;

        cr->prev_client = LFS_NO_CLIENT_LE;
        cr->next_client = LFS_NO_CLIENT_LE;

        return ra;
}

static u32 final_log_off(struct ntfs_log *log, u64 lsn, u32 data_len)
{
        u32 base_vbo = lsn << 3;
        u32 final_log_off = (base_vbo & log->seq_num_mask) & ~log->page_mask;
        u32 page_off = base_vbo & log->page_mask;
        u32 tail = log->page_size - page_off;

        page_off -= 1;

        /* Add the length of the header. */
        data_len += log->record_header_len;

        /*
         * If this lsn is contained this log page we are done.
         * Otherwise we need to walk through several log pages.
         */
        if (data_len > tail) {
                data_len -= tail;
                tail = log->data_size;
                page_off = log->data_off - 1;

                for (;;) {
                        final_log_off = next_page_off(log, final_log_off);

                        /*
                         * We are done if the remaining bytes
                         * fit on this page.
                         */
                        if (data_len <= tail)
                                break;
                        data_len -= tail;
                }
        }

        /*
         * We add the remaining bytes to our starting position on this page
         * and then add that value to the file offset of this log page.
         */
        return final_log_off + data_len + page_off;
}

static int next_log_lsn(struct ntfs_log *log, const struct LFS_RECORD_HDR *rh,
                        u64 *lsn)
{
        int err;
        u64 this_lsn = le64_to_cpu(rh->this_lsn);
        u32 vbo = lsn_to_vbo(log, this_lsn);
        u32 end =
                final_log_off(log, this_lsn, le32_to_cpu(rh->client_data_len));
        u32 hdr_off = end & ~log->sys_page_mask;
        u64 seq = this_lsn >> log->file_data_bits;
        struct RECORD_PAGE_HDR *page = NULL;

        /* Remember if we wrapped. */
        if (end <= vbo)
                seq += 1;

        /* Log page header for this page. */
        err = read_log_page(log, hdr_off, &page, NULL);
        if (err)
                return err;

        /*
         * If the lsn we were given was not the last lsn on this page,
         * then the starting offset for the next lsn is on a quad word
         * boundary following the last file offset for the current lsn.
         * Otherwise the file offset is the start of the data on the next page.
         */
        if (this_lsn == le64_to_cpu(page->rhdr.lsn)) {
                /* If we wrapped, we need to increment the sequence number. */
                hdr_off = next_page_off(log, hdr_off);
                if (hdr_off == log->first_page)
                        seq += 1;

                vbo = hdr_off + log->data_off;
        } else {
                vbo = ALIGN(end, 8);
        }

        /* Compute the lsn based on the file offset and the sequence count. */
        *lsn = vbo_to_lsn(log, vbo, seq);

        /*
         * If this lsn is within the legal range for the file, we return true.
         * Otherwise false indicates that there are no more lsn's.
         */
        if (!is_lsn_in_file(log, *lsn))
                *lsn = 0;

        kfree(page);

        return 0;
}

/*
 * current_log_avail - Calculate the number of bytes available for log records.
 */
static u32 current_log_avail(struct ntfs_log *log)
{
        u32 oldest_off, next_free_off, free_bytes;

        if (log->l_flags & NTFSLOG_NO_LAST_LSN) {
                /* The entire file is available. */
                return log->max_current_avail;
        }

        /*
         * If there is a last lsn the restart area then we know that we will
         * have to compute the free range.
         * If there is no oldest lsn then start at the first page of the file.
         */
        oldest_off = (log->l_flags & NTFSLOG_NO_OLDEST_LSN)
                             ? log->first_page
                             : (log->oldest_lsn_off & ~log->sys_page_mask);

        /*
         * We will use the next log page offset to compute the next free page.
         * If we are going to reuse this page go to the next page.
         * If we are at the first page then use the end of the file.
         */
        next_free_off = (log->l_flags & NTFSLOG_REUSE_TAIL)
                                ? log->next_page + log->page_size
                                : log->next_page == log->first_page
                                          ? log->l_size
                                          : log->next_page;

        /* If the two offsets are the same then there is no available space. */
        if (oldest_off == next_free_off)
                return 0;
        /*
         * If the free offset follows the oldest offset then subtract
         * this range from the total available pages.
         */
        free_bytes =
                oldest_off < next_free_off
                        ? log->total_avail_pages - (next_free_off - oldest_off)
                        : oldest_off - next_free_off;

        free_bytes >>= log->page_bits;
        return free_bytes * log->reserved;
}

static bool check_subseq_log_page(struct ntfs_log *log,
                                  const struct RECORD_PAGE_HDR *rp, u32 vbo,
                                  u64 seq)
{
        u64 lsn_seq;
        const struct NTFS_RECORD_HEADER *rhdr = &rp->rhdr;
        u64 lsn = le64_to_cpu(rhdr->lsn);

        if (rhdr->sign == NTFS_FFFF_SIGNATURE || !rhdr->sign)
                return false;

        /*
         * If the last lsn on the page occurs was written after the page
         * that caused the original error then we have a fatal error.
         */
        lsn_seq = lsn >> log->file_data_bits;

        /*
         * If the sequence number for the lsn the page is equal or greater
         * than lsn we expect, then this is a subsequent write.
         */
        return lsn_seq >= seq ||
               (lsn_seq == seq - 1 && log->first_page == vbo &&
                vbo != (lsn_to_vbo(log, lsn) & ~log->page_mask));
}

/*
 * last_log_lsn
 *
 * Walks through the log pages for a file, searching for the
 * last log page written to the file.
 */
static int last_log_lsn(struct ntfs_log *log)
{
        int err;
        bool usa_error = false;
        bool replace_page = false;
        bool reuse_page = log->l_flags & NTFSLOG_REUSE_TAIL;
        bool wrapped_file, wrapped;

        u32 page_cnt = 1, page_pos = 1;
        u32 page_off = 0, page_off1 = 0, saved_off = 0;
        u32 final_off, second_off, final_off_prev = 0, second_off_prev = 0;
        u32 first_file_off = 0, second_file_off = 0;
        u32 part_io_count = 0;
        u32 tails = 0;
        u32 this_off, curpage_off, nextpage_off, remain_pages;

        u64 expected_seq, seq_base = 0, lsn_base = 0;
        u64 best_lsn, best_lsn1, best_lsn2;
        u64 lsn_cur, lsn1, lsn2;
        u64 last_ok_lsn = reuse_page ? log->last_lsn : 0;

        u16 cur_pos, best_page_pos;

        struct RECORD_PAGE_HDR *page = NULL;
        struct RECORD_PAGE_HDR *tst_page = NULL;
        struct RECORD_PAGE_HDR *first_tail = NULL;
        struct RECORD_PAGE_HDR *second_tail = NULL;
        struct RECORD_PAGE_HDR *tail_page = NULL;
        struct RECORD_PAGE_HDR *second_tail_prev = NULL;
        struct RECORD_PAGE_HDR *first_tail_prev = NULL;
        struct RECORD_PAGE_HDR *page_bufs = NULL;
        struct RECORD_PAGE_HDR *best_page;

        if (log->major_ver >= 2) {
                final_off = 0x02 * log->page_size;
                second_off = 0x12 * log->page_size;

                // 0x10 == 0x12 - 0x2
                page_bufs = kmalloc(log->page_size * 0x10, GFP_NOFS);
                if (!page_bufs)
                        return -ENOMEM;
        } else {
                second_off = log->first_page - log->page_size;
                final_off = second_off - log->page_size;
        }

next_tail:
        /* Read second tail page (at pos 3/0x12000). */
        if (read_log_page(log, second_off, &second_tail, &usa_error) ||
            usa_error || second_tail->rhdr.sign != NTFS_RCRD_SIGNATURE) {
                kfree(second_tail);
                second_tail = NULL;
                second_file_off = 0;
                lsn2 = 0;
        } else {
                second_file_off = hdr_file_off(log, second_tail);
                lsn2 = le64_to_cpu(second_tail->record_hdr.last_end_lsn);
        }

        /* Read first tail page (at pos 2/0x2000). */
        if (read_log_page(log, final_off, &first_tail, &usa_error) ||
            usa_error || first_tail->rhdr.sign != NTFS_RCRD_SIGNATURE) {
                kfree(first_tail);
                first_tail = NULL;
                first_file_off = 0;
                lsn1 = 0;
        } else {
                first_file_off = hdr_file_off(log, first_tail);
                lsn1 = le64_to_cpu(first_tail->record_hdr.last_end_lsn);
        }

        if (log->major_ver < 2) {
                int best_page;

                first_tail_prev = first_tail;
                final_off_prev = first_file_off;
                second_tail_prev = second_tail;
                second_off_prev = second_file_off;
                tails = 1;

                if (!first_tail && !second_tail)
                        goto tail_read;

                if (first_tail && second_tail)
                        best_page = lsn1 < lsn2 ? 1 : 0;
                else if (first_tail)
                        best_page = 0;
                else
                        best_page = 1;

                page_off = best_page ? second_file_off : first_file_off;
                seq_base = (best_page ? lsn2 : lsn1) >> log->file_data_bits;
                goto tail_read;
        }

        best_lsn1 = first_tail ? base_lsn(log, first_tail, first_file_off) : 0;
        best_lsn2 =
                second_tail ? base_lsn(log, second_tail, second_file_off) : 0;

        if (first_tail && second_tail) {
                if (best_lsn1 > best_lsn2) {
                        best_lsn = best_lsn1;
                        best_page = first_tail;
                        this_off = first_file_off;
                } else {
                        best_lsn = best_lsn2;
                        best_page = second_tail;
                        this_off = second_file_off;
                }
        } else if (first_tail) {
                best_lsn = best_lsn1;
                best_page = first_tail;
                this_off = first_file_off;
        } else if (second_tail) {
                best_lsn = best_lsn2;
                best_page = second_tail;
                this_off = second_file_off;
        } else {
                goto tail_read;
        }

        best_page_pos = le16_to_cpu(best_page->page_pos);

        if (!tails) {
                if (best_page_pos == page_pos) {
                        seq_base = best_lsn >> log->file_data_bits;
                        saved_off = page_off = le32_to_cpu(best_page->file_off);
                        lsn_base = best_lsn;

                        memmove(page_bufs, best_page, log->page_size);

                        page_cnt = le16_to_cpu(best_page->page_count);
                        if (page_cnt > 1)
                                page_pos += 1;

                        tails = 1;
                }
        } else if (seq_base == (best_lsn >> log->file_data_bits) &&
                   saved_off + log->page_size == this_off &&
                   lsn_base < best_lsn &&
                   (page_pos != page_cnt || best_page_pos == page_pos ||
                    best_page_pos == 1) &&
                   (page_pos >= page_cnt || best_page_pos == page_pos)) {
                u16 bppc = le16_to_cpu(best_page->page_count);

                saved_off += log->page_size;
                lsn_base = best_lsn;

                memmove(Add2Ptr(page_bufs, tails * log->page_size), best_page,
                        log->page_size);

                tails += 1;

                if (best_page_pos != bppc) {
                        page_cnt = bppc;
                        page_pos = best_page_pos;

                        if (page_cnt > 1)
                                page_pos += 1;
                } else {
                        page_pos = page_cnt = 1;
                }
        } else {
                kfree(first_tail);
                kfree(second_tail);
                goto tail_read;
        }

        kfree(first_tail_prev);
        first_tail_prev = first_tail;
        final_off_prev = first_file_off;
        first_tail = NULL;

        kfree(second_tail_prev);
        second_tail_prev = second_tail;
        second_off_prev = second_file_off;
        second_tail = NULL;

        final_off += log->page_size;
        second_off += log->page_size;

        if (tails < 0x10)
                goto next_tail;
tail_read:
        first_tail = first_tail_prev;
        final_off = final_off_prev;

        second_tail = second_tail_prev;
        second_off = second_off_prev;

        page_cnt = page_pos = 1;

        curpage_off = seq_base == log->seq_num ? min(log->next_page, page_off)
                                               : log->next_page;

        wrapped_file =
                curpage_off == log->first_page &&
                !(log->l_flags & (NTFSLOG_NO_LAST_LSN | NTFSLOG_REUSE_TAIL));

        expected_seq = wrapped_file ? (log->seq_num + 1) : log->seq_num;

        nextpage_off = curpage_off;

next_page:
        tail_page = NULL;
        /* Read the next log page. */
        err = read_log_page(log, curpage_off, &page, &usa_error);

        /* Compute the next log page offset the file. */
        nextpage_off = next_page_off(log, curpage_off);
        wrapped = nextpage_off == log->first_page;

        if (tails > 1) {
                struct RECORD_PAGE_HDR *cur_page =
                        Add2Ptr(page_bufs, curpage_off - page_off);

                if (curpage_off == saved_off) {
                        tail_page = cur_page;
                        goto use_tail_page;
                }

                if (page_off > curpage_off || curpage_off >= saved_off)
                        goto use_tail_page;

                if (page_off1)
                        goto use_cur_page;

                if (!err && !usa_error &&
                    page->rhdr.sign == NTFS_RCRD_SIGNATURE &&
                    cur_page->rhdr.lsn == page->rhdr.lsn &&
                    cur_page->record_hdr.next_record_off ==
                            page->record_hdr.next_record_off &&
                    ((page_pos == page_cnt &&
                      le16_to_cpu(page->page_pos) == 1) ||
                     (page_pos != page_cnt &&
                      le16_to_cpu(page->page_pos) == page_pos + 1 &&
                      le16_to_cpu(page->page_count) == page_cnt))) {
                        cur_page = NULL;
                        goto use_tail_page;
                }

                page_off1 = page_off;

use_cur_page:

                lsn_cur = le64_to_cpu(cur_page->rhdr.lsn);

                if (last_ok_lsn !=
                            le64_to_cpu(cur_page->record_hdr.last_end_lsn) &&
                    ((lsn_cur >> log->file_data_bits) +
                     ((curpage_off <
                       (lsn_to_vbo(log, lsn_cur) & ~log->page_mask))
                              ? 1
                              : 0)) != expected_seq) {
                        goto check_tail;
                }

                if (!is_log_record_end(cur_page)) {
                        tail_page = NULL;
                        last_ok_lsn = lsn_cur;
                        goto next_page_1;
                }

                log->seq_num = expected_seq;
                log->l_flags &= ~NTFSLOG_NO_LAST_LSN;
                log->last_lsn = le64_to_cpu(cur_page->record_hdr.last_end_lsn);
                log->ra->current_lsn = cur_page->record_hdr.last_end_lsn;

                if (log->record_header_len <=
                    log->page_size -
                            le16_to_cpu(cur_page->record_hdr.next_record_off)) {
                        log->l_flags |= NTFSLOG_REUSE_TAIL;
                        log->next_page = curpage_off;
                } else {
                        log->l_flags &= ~NTFSLOG_REUSE_TAIL;
                        log->next_page = nextpage_off;
                }

                if (wrapped_file)
                        log->l_flags |= NTFSLOG_WRAPPED;

                last_ok_lsn = le64_to_cpu(cur_page->record_hdr.last_end_lsn);
                goto next_page_1;
        }

        /*
         * If we are at the expected first page of a transfer check to see
         * if either tail copy is at this offset.
         * If this page is the last page of a transfer, check if we wrote
         * a subsequent tail copy.
         */
        if (page_cnt == page_pos || page_cnt == page_pos + 1) {
                /*
                 * Check if the offset matches either the first or second
                 * tail copy. It is possible it will match both.
                 */
                if (curpage_off == final_off)
                        tail_page = first_tail;

                /*
                 * If we already matched on the first page then
                 * check the ending lsn's.
                 */
                if (curpage_off == second_off) {
                        if (!tail_page ||
                            (second_tail &&
                             le64_to_cpu(second_tail->record_hdr.last_end_lsn) >
                                     le64_to_cpu(first_tail->record_hdr
                                                         .last_end_lsn))) {
                                tail_page = second_tail;
                        }
                }
        }

use_tail_page:
        if (tail_page) {
                /* We have a candidate for a tail copy. */
                lsn_cur = le64_to_cpu(tail_page->record_hdr.last_end_lsn);

                if (last_ok_lsn < lsn_cur) {
                        /*
                         * If the sequence number is not expected,
                         * then don't use the tail copy.
                         */
                        if (expected_seq != (lsn_cur >> log->file_data_bits))
                                tail_page = NULL;
                } else if (last_ok_lsn > lsn_cur) {
                        /*
                         * If the last lsn is greater than the one on
                         * this page then forget this tail.
                         */
                        tail_page = NULL;
                }
        }

        /*
         *If we have an error on the current page,
         * we will break of this loop.
         */
        if (err || usa_error)
                goto check_tail;

        /*
         * Done if the last lsn on this page doesn't match the previous known
         * last lsn or the sequence number is not expected.
         */
        lsn_cur = le64_to_cpu(page->rhdr.lsn);
        if (last_ok_lsn != lsn_cur &&
            expected_seq != (lsn_cur >> log->file_data_bits)) {
                goto check_tail;
        }

        /*
         * Check that the page position and page count values are correct.
         * If this is the first page of a transfer the position must be 1
         * and the count will be unknown.
         */
        if (page_cnt == page_pos) {
                if (page->page_pos != cpu_to_le16(1) &&
                    (!reuse_page || page->page_pos != page->page_count)) {
                        /*
                         * If the current page is the first page we are
                         * looking at and we are reusing this page then
                         * it can be either the first or last page of a
                         * transfer. Otherwise it can only be the first.
                         */
                        goto check_tail;
                }
        } else if (le16_to_cpu(page->page_count) != page_cnt ||
                   le16_to_cpu(page->page_pos) != page_pos + 1) {
                /*
                 * The page position better be 1 more than the last page
                 * position and the page count better match.
                 */
                goto check_tail;
        }

        /*
         * We have a valid page the file and may have a valid page
         * the tail copy area.
         * If the tail page was written after the page the file then
         * break of the loop.
         */
        if (tail_page &&
            le64_to_cpu(tail_page->record_hdr.last_end_lsn) > lsn_cur) {
                /* Remember if we will replace the page. */
                replace_page = true;
                goto check_tail;
        }

        tail_page = NULL;

        if (is_log_record_end(page)) {
                /*
                 * Since we have read this page we know the sequence number
                 * is the same as our expected value.
                 */
                log->seq_num = expected_seq;
                log->last_lsn = le64_to_cpu(page->record_hdr.last_end_lsn);
                log->ra->current_lsn = page->record_hdr.last_end_lsn;
                log->l_flags &= ~NTFSLOG_NO_LAST_LSN;

                /*
                 * If there is room on this page for another header then
                 * remember we want to reuse the page.
                 */
                if (log->record_header_len <=
                    log->page_size -
                            le16_to_cpu(page->record_hdr.next_record_off)) {
                        log->l_flags |= NTFSLOG_REUSE_TAIL;
                        log->next_page = curpage_off;
                } else {
                        log->l_flags &= ~NTFSLOG_REUSE_TAIL;
                        log->next_page = nextpage_off;
                }

                /* Remember if we wrapped the log file. */
                if (wrapped_file)
                        log->l_flags |= NTFSLOG_WRAPPED;
        }

        /*
         * Remember the last page count and position.
         * Also remember the last known lsn.
         */
        page_cnt = le16_to_cpu(page->page_count);
        page_pos = le16_to_cpu(page->page_pos);
        last_ok_lsn = le64_to_cpu(page->rhdr.lsn);

next_page_1:

        if (wrapped) {
                expected_seq += 1;
                wrapped_file = 1;
        }

        curpage_off = nextpage_off;
        kfree(page);
        page = NULL;
        reuse_page = 0;
        goto next_page;

check_tail:
        if (tail_page) {
                log->seq_num = expected_seq;
                log->last_lsn = le64_to_cpu(tail_page->record_hdr.last_end_lsn);
                log->ra->current_lsn = tail_page->record_hdr.last_end_lsn;
                log->l_flags &= ~NTFSLOG_NO_LAST_LSN;

                if (log->page_size -
                            le16_to_cpu(
                                    tail_page->record_hdr.next_record_off) >=
                    log->record_header_len) {
                        log->l_flags |= NTFSLOG_REUSE_TAIL;
                        log->next_page = curpage_off;
                } else {
                        log->l_flags &= ~NTFSLOG_REUSE_TAIL;
                        log->next_page = nextpage_off;
                }

                if (wrapped)
                        log->l_flags |= NTFSLOG_WRAPPED;
        }

        /* Remember that the partial IO will start at the next page. */
        second_off = nextpage_off;

        /*
         * If the next page is the first page of the file then update
         * the sequence number for log records which begon the next page.
         */
        if (wrapped)
                expected_seq += 1;

        /*
         * If we have a tail copy or are performing single page I/O we can
         * immediately look at the next page.
         */
        if (replace_page || (log->ra->flags & RESTART_SINGLE_PAGE_IO)) {
                page_cnt = 2;
                page_pos = 1;
                goto check_valid;
        }

        if (page_pos != page_cnt)
                goto check_valid;
        /*
         * If the next page causes us to wrap to the beginning of the log
         * file then we know which page to check next.
         */
        if (wrapped) {
                page_cnt = 2;
                page_pos = 1;
                goto check_valid;
        }

        cur_pos = 2;

next_test_page:
        kfree(tst_page);
        tst_page = NULL;

        /* Walk through the file, reading log pages. */
        err = read_log_page(log, nextpage_off, &tst_page, &usa_error);

        /*
         * If we get a USA error then assume that we correctly found
         * the end of the original transfer.
         */
        if (usa_error)
                goto file_is_valid;

        /*
         * If we were able to read the page, we examine it to see if it
         * is the same or different Io block.
         */
        if (err)
                goto next_test_page_1;

        if (le16_to_cpu(tst_page->page_pos) == cur_pos &&
            check_subseq_log_page(log, tst_page, nextpage_off, expected_seq)) {
                page_cnt = le16_to_cpu(tst_page->page_count) + 1;
                page_pos = le16_to_cpu(tst_page->page_pos);
                goto check_valid;
        } else {
                goto file_is_valid;
        }

next_test_page_1:

        nextpage_off = next_page_off(log, curpage_off);
        wrapped = nextpage_off == log->first_page;

        if (wrapped) {
                expected_seq += 1;
                page_cnt = 2;
                page_pos = 1;
        }

        cur_pos += 1;
        part_io_count += 1;
        if (!wrapped)
                goto next_test_page;

check_valid:
        /* Skip over the remaining pages this transfer. */
        remain_pages = page_cnt - page_pos - 1;
        part_io_count += remain_pages;

        while (remain_pages--) {
                nextpage_off = next_page_off(log, curpage_off);
                wrapped = nextpage_off == log->first_page;

                if (wrapped)
                        expected_seq += 1;
        }

        /* Call our routine to check this log page. */
        kfree(tst_page);
        tst_page = NULL;

        err = read_log_page(log, nextpage_off, &tst_page, &usa_error);
        if (!err && !usa_error &&
            check_subseq_log_page(log, tst_page, nextpage_off, expected_seq)) {
                err = -EINVAL;
                goto out;
        }

file_is_valid:

        /* We have a valid file. */
        if (page_off1 || tail_page) {
                struct RECORD_PAGE_HDR *tmp_page;

                if (sb_rdonly(log->ni->mi.sbi->sb)) {
                        err = -EROFS;
                        goto out;
                }

                if (page_off1) {
                        tmp_page = Add2Ptr(page_bufs, page_off1 - page_off);
                        tails -= (page_off1 - page_off) / log->page_size;
                        if (!tail_page)
                                tails -= 1;
                } else {
                        tmp_page = tail_page;
                        tails = 1;
                }

                while (tails--) {
                        u64 off = hdr_file_off(log, tmp_page);

                        if (!page) {
                                page = kmalloc(log->page_size, GFP_NOFS);
                                if (!page)
                                        return -ENOMEM;
                        }

                        /*
                         * Correct page and copy the data from this page
                         * into it and flush it to disk.
                         */
                        memcpy(page, tmp_page, log->page_size);

                        /* Fill last flushed lsn value flush the page. */
                        if (log->major_ver < 2)
                                page->rhdr.lsn = page->record_hdr.last_end_lsn;
                        else
                                page->file_off = 0;

                        page->page_pos = page->page_count = cpu_to_le16(1);

                        ntfs_fix_pre_write(&page->rhdr, log->page_size);

                        err = ntfs_sb_write_run(log->ni->mi.sbi,
                                                &log->ni->file.run, off, page,
                                                log->page_size, 0);

                        if (err)
                                goto out;

                        if (part_io_count && second_off == off) {
                                second_off += log->page_size;
                                part_io_count -= 1;
                        }

                        tmp_page = Add2Ptr(tmp_page, log->page_size);
                }
        }

        if (part_io_count) {
                if (sb_rdonly(log->ni->mi.sbi->sb)) {
                        err = -EROFS;
                        goto out;
                }
        }

out:
        kfree(second_tail);
        kfree(first_tail);
        kfree(page);
        kfree(tst_page);
        kfree(page_bufs);

        return err;
}

/*
 * read_log_rec_buf - Copy a log record from the file to a buffer.
 *
 * The log record may span several log pages and may even wrap the file.
 */
static int read_log_rec_buf(struct ntfs_log *log,
                            const struct LFS_RECORD_HDR *rh, void *buffer)
{
        int err;
        struct RECORD_PAGE_HDR *ph = NULL;
        u64 lsn = le64_to_cpu(rh->this_lsn);
        u32 vbo = lsn_to_vbo(log, lsn) & ~log->page_mask;
        u32 off = lsn_to_page_off(log, lsn) + log->record_header_len;
        u32 data_len = le32_to_cpu(rh->client_data_len);

        /*
         * While there are more bytes to transfer,
         * we continue to attempt to perform the read.
         */
        for (;;) {
                bool usa_error;
                u32 tail = log->page_size - off;

                if (tail >= data_len)
                        tail = data_len;

                data_len -= tail;

                err = read_log_page(log, vbo, &ph, &usa_error);
                if (err)
                        goto out;

                /*
                 * The last lsn on this page better be greater or equal
                 * to the lsn we are copying.
                 */
                if (lsn > le64_to_cpu(ph->rhdr.lsn)) {
                        err = -EINVAL;
                        goto out;
                }

                memcpy(buffer, Add2Ptr(ph, off), tail);

                /* If there are no more bytes to transfer, we exit the loop. */
                if (!data_len) {
                        if (!is_log_record_end(ph) ||
                            lsn > le64_to_cpu(ph->record_hdr.last_end_lsn)) {
                                err = -EINVAL;
                                goto out;
                        }
                        break;
                }

                if (ph->rhdr.lsn == ph->record_hdr.last_end_lsn ||
                    lsn > le64_to_cpu(ph->rhdr.lsn)) {
                        err = -EINVAL;
                        goto out;
                }

                vbo = next_page_off(log, vbo);
                off = log->data_off;

                /*
                 * Adjust our pointer the user's buffer to transfer
                 * the next block to.
                 */
                buffer = Add2Ptr(buffer, tail);
        }

out:
        kfree(ph);
        return err;
}

static int read_rst_area(struct ntfs_log *log, struct NTFS_RESTART **rst_,
                         u64 *lsn)
{
        int err;
        struct LFS_RECORD_HDR *rh = NULL;
        const struct CLIENT_REC *cr =
                Add2Ptr(log->ra, le16_to_cpu(log->ra->client_off));
        u64 lsnr, lsnc = le64_to_cpu(cr->restart_lsn);
        u32 len;
        struct NTFS_RESTART *rst;

        *lsn = 0;
        *rst_ = NULL;

        /* If the client doesn't have a restart area, go ahead and exit now. */
        if (!lsnc)
                return 0;

        err = read_log_page(log, lsn_to_vbo(log, lsnc),
                            (struct RECORD_PAGE_HDR **)&rh, NULL);
        if (err)
                return err;

        rst = NULL;
        lsnr = le64_to_cpu(rh->this_lsn);

        if (lsnc != lsnr) {
                /* If the lsn values don't match, then the disk is corrupt. */
                err = -EINVAL;
                goto out;
        }

        *lsn = lsnr;
        len = le32_to_cpu(rh->client_data_len);

        if (!len) {
                err = 0;
                goto out;
        }

        if (len < sizeof(struct NTFS_RESTART)) {
                err = -EINVAL;
                goto out;
        }

        rst = kmalloc(len, GFP_NOFS);
        if (!rst) {
                err = -ENOMEM;
                goto out;
        }

        /* Copy the data into the 'rst' buffer. */
        err = read_log_rec_buf(log, rh, rst);
        if (err)
                goto out;

        *rst_ = rst;
        rst = NULL;

out:
        kfree(rh);
        kfree(rst);

        return err;
}

static int find_log_rec(struct ntfs_log *log, u64 lsn, struct lcb *lcb)
{
        int err;
        struct LFS_RECORD_HDR *rh = lcb->lrh;
        u32 rec_len, len;

        /* Read the record header for this lsn. */
        if (!rh) {
                err = read_log_page(log, lsn_to_vbo(log, lsn),
                                    (struct RECORD_PAGE_HDR **)&rh, NULL);

                lcb->lrh = rh;
                if (err)
                        return err;
        }

        /*
         * If the lsn the log record doesn't match the desired
         * lsn then the disk is corrupt.
         */
        if (lsn != le64_to_cpu(rh->this_lsn))
                return -EINVAL;

        len = le32_to_cpu(rh->client_data_len);

        /*
         * Check that the length field isn't greater than the total
         * available space the log file.
         */
        rec_len = len + log->record_header_len;
        if (rec_len >= log->total_avail)
                return -EINVAL;

        /*
         * If the entire log record is on this log page,
         * put a pointer to the log record the context block.
         */
        if (rh->flags & LOG_RECORD_MULTI_PAGE) {
                void *lr = kmalloc(len, GFP_NOFS);

                if (!lr)
                        return -ENOMEM;

                lcb->log_rec = lr;
                lcb->alloc = true;

                /* Copy the data into the buffer returned. */
                err = read_log_rec_buf(log, rh, lr);
                if (err)
                        return err;
        } else {
                /* If beyond the end of the current page -> an error. */
                u32 page_off = lsn_to_page_off(log, lsn);

                if (page_off + len + log->record_header_len > log->page_size)
                        return -EINVAL;

                lcb->log_rec = Add2Ptr(rh, sizeof(struct LFS_RECORD_HDR));
                lcb->alloc = false;
        }

        return 0;
}

/*
 * read_log_rec_lcb - Init the query operation.
 */
static int read_log_rec_lcb(struct ntfs_log *log, u64 lsn, u32 ctx_mode,
                            struct lcb **lcb_)
{
        int err;
        const struct CLIENT_REC *cr;
        struct lcb *lcb;

        switch (ctx_mode) {
        case lcb_ctx_undo_next:
        case lcb_ctx_prev:
        case lcb_ctx_next:
                break;
        default:
                return -EINVAL;
        }

        /* Check that the given lsn is the legal range for this client. */
        cr = Add2Ptr(log->ra, le16_to_cpu(log->ra->client_off));

        if (!verify_client_lsn(log, cr, lsn))
                return -EINVAL;

        lcb = kzalloc(sizeof(struct lcb), GFP_NOFS);
        if (!lcb)
                return -ENOMEM;
        lcb->client = log->client_id;
        lcb->ctx_mode = ctx_mode;

        /* Find the log record indicated by the given lsn. */
        err = find_log_rec(log, lsn, lcb);
        if (err)
                goto out;

        *lcb_ = lcb;
        return 0;

out:
        lcb_put(lcb);
        *lcb_ = NULL;
        return err;
}

/*
 * find_client_next_lsn
 *
 * Attempt to find the next lsn to return to a client based on the context mode.
 */
static int find_client_next_lsn(struct ntfs_log *log, struct lcb *lcb, u64 *lsn)
{
        int err;
        u64 next_lsn;
        struct LFS_RECORD_HDR *hdr;

        hdr = lcb->lrh;
        *lsn = 0;

        if (lcb_ctx_next != lcb->ctx_mode)
                goto check_undo_next;

        /* Loop as long as another lsn can be found. */
        for (;;) {
                u64 current_lsn;

                err = next_log_lsn(log, hdr, &current_lsn);
                if (err)
                        goto out;

                if (!current_lsn)
                        break;

                if (hdr != lcb->lrh)
                        kfree(hdr);

                hdr = NULL;
                err = read_log_page(log, lsn_to_vbo(log, current_lsn),
                                    (struct RECORD_PAGE_HDR **)&hdr, NULL);
                if (err)
                        goto out;

                if (memcmp(&hdr->client, &lcb->client,
                           sizeof(struct CLIENT_ID))) {
                        /*err = -EINVAL; */
                } else if (LfsClientRecord == hdr->record_type) {
                        kfree(lcb->lrh);
                        lcb->lrh = hdr;
                        *lsn = current_lsn;
                        return 0;
                }
        }

out:
        if (hdr != lcb->lrh)
                kfree(hdr);
        return err;

check_undo_next:
        if (lcb_ctx_undo_next == lcb->ctx_mode)
                next_lsn = le64_to_cpu(hdr->client_undo_next_lsn);
        else if (lcb_ctx_prev == lcb->ctx_mode)
                next_lsn = le64_to_cpu(hdr->client_prev_lsn);
        else
                return 0;

        if (!next_lsn)
                return 0;

        if (!verify_client_lsn(
                    log, Add2Ptr(log->ra, le16_to_cpu(log->ra->client_off)),
                    next_lsn))
                return 0;

        hdr = NULL;
        err = read_log_page(log, lsn_to_vbo(log, next_lsn),
                            (struct RECORD_PAGE_HDR **)&hdr, NULL);
        if (err)
                return err;
        kfree(lcb->lrh);
        lcb->lrh = hdr;

        *lsn = next_lsn;

        return 0;
}

static int read_next_log_rec(struct ntfs_log *log, struct lcb *lcb, u64 *lsn)
{
        int err;

        err = find_client_next_lsn(log, lcb, lsn);
        if (err)
                return err;

        if (!*lsn)
                return 0;

        if (lcb->alloc)
                kfree(lcb->log_rec);

        lcb->log_rec = NULL;
        lcb->alloc = false;
        kfree(lcb->lrh);
        lcb->lrh = NULL;

        return find_log_rec(log, *lsn, lcb);
}

static inline bool check_index_header(const struct INDEX_HDR *hdr, size_t bytes)
{
        __le16 mask;
        u32 min_de, de_off, used, total;
        const struct NTFS_DE *e;

        if (hdr_has_subnode(hdr)) {
                min_de = sizeof(struct NTFS_DE) + sizeof(u64);
                mask = NTFS_IE_HAS_SUBNODES;
        } else {
                min_de = sizeof(struct NTFS_DE);
                mask = 0;
        }

        de_off = le32_to_cpu(hdr->de_off);
        used = le32_to_cpu(hdr->used);
        total = le32_to_cpu(hdr->total);

        if (de_off > bytes - min_de || used > bytes || total > bytes ||
            de_off + min_de > used || used > total) {
                return false;
        }

        e = Add2Ptr(hdr, de_off);
        for (;;) {
                u16 esize = le16_to_cpu(e->size);
                struct NTFS_DE *next = Add2Ptr(e, esize);

                if (esize < min_de || PtrOffset(hdr, next) > used ||
                    (e->flags & NTFS_IE_HAS_SUBNODES) != mask) {
                        return false;
                }

                if (de_is_last(e))
                        break;

                e = next;
        }

        return true;
}

static inline bool check_index_buffer(const struct INDEX_BUFFER *ib, u32 bytes)
{
        u16 fo;
        const struct NTFS_RECORD_HEADER *r = &ib->rhdr;

        if (r->sign != NTFS_INDX_SIGNATURE)
                return false;

        fo = (SECTOR_SIZE - ((bytes >> SECTOR_SHIFT) + 1) * sizeof(short));

        if (le16_to_cpu(r->fix_off) > fo)
                return false;

        if ((le16_to_cpu(r->fix_num) - 1) * SECTOR_SIZE != bytes)
                return false;

        return check_index_header(&ib->ihdr,
                                  bytes - offsetof(struct INDEX_BUFFER, ihdr));
}

static inline bool check_index_root(const struct ATTRIB *attr,
                                    struct ntfs_sb_info *sbi)
{
        bool ret;
        const struct INDEX_ROOT *root = resident_data(attr);
        u8 index_bits = le32_to_cpu(root->index_block_size) >= sbi->cluster_size
                                ? sbi->cluster_bits
                                : SECTOR_SHIFT;
        u8 block_clst = root->index_block_clst;

        if (le32_to_cpu(attr->res.data_size) < sizeof(struct INDEX_ROOT) ||
            (root->type != ATTR_NAME && root->type != ATTR_ZERO) ||
            (root->type == ATTR_NAME &&
             root->rule != NTFS_COLLATION_TYPE_FILENAME) ||
            (le32_to_cpu(root->index_block_size) !=
             (block_clst << index_bits)) ||
            (block_clst != 1 && block_clst != 2 && block_clst != 4 &&
             block_clst != 8 && block_clst != 0x10 && block_clst != 0x20 &&
             block_clst != 0x40 && block_clst != 0x80)) {
                return false;
        }

        ret = check_index_header(&root->ihdr,
                                 le32_to_cpu(attr->res.data_size) -
                                         offsetof(struct INDEX_ROOT, ihdr));
        return ret;
}

static inline bool check_attr(const struct MFT_REC *rec,
                              const struct ATTRIB *attr,
                              struct ntfs_sb_info *sbi)
{
        u32 asize = le32_to_cpu(attr->size);
        u32 rsize = 0;
        u64 dsize, svcn, evcn;
        u16 run_off;

        /* Check the fixed part of the attribute record header. */
        if (asize >= sbi->record_size ||
            asize + PtrOffset(rec, attr) >= sbi->record_size ||
            (attr->name_len &&
             le16_to_cpu(attr->name_off) + attr->name_len * sizeof(short) >
                     asize)) {
                return false;
        }

        /* Check the attribute fields. */
        switch (attr->non_res) {
        case 0:
                rsize = le32_to_cpu(attr->res.data_size);
                if (rsize >= asize ||
                    le16_to_cpu(attr->res.data_off) + rsize > asize) {
                        return false;
                }
                break;

        case 1:
                dsize = le64_to_cpu(attr->nres.data_size);
                svcn = le64_to_cpu(attr->nres.svcn);
                evcn = le64_to_cpu(attr->nres.evcn);
                run_off = le16_to_cpu(attr->nres.run_off);

                if (svcn > evcn + 1 || run_off >= asize ||
                    le64_to_cpu(attr->nres.valid_size) > dsize ||
                    dsize > le64_to_cpu(attr->nres.alloc_size)) {
                        return false;
                }

                if (run_unpack(NULL, sbi, 0, svcn, evcn, svcn,
                               Add2Ptr(attr, run_off), asize - run_off) < 0) {
                        return false;
                }

                return true;

        default:
                return false;
        }

        switch (attr->type) {
        case ATTR_NAME:
                if (fname_full_size(Add2Ptr(
                            attr, le16_to_cpu(attr->res.data_off))) > asize) {
                        return false;
                }
                break;

        case ATTR_ROOT:
                return check_index_root(attr, sbi);

        case ATTR_STD:
                if (rsize < sizeof(struct ATTR_STD_INFO5) &&
                    rsize != sizeof(struct ATTR_STD_INFO)) {
                        return false;
                }
                break;

        case ATTR_LIST:
        case ATTR_ID:
        case ATTR_SECURE:
        case ATTR_LABEL:
        case ATTR_VOL_INFO:
        case ATTR_DATA:
        case ATTR_ALLOC:
        case ATTR_BITMAP:
        case ATTR_REPARSE:
        case ATTR_EA_INFO:
        case ATTR_EA:
        case ATTR_PROPERTYSET:
        case ATTR_LOGGED_UTILITY_STREAM:
                break;

        default:
                return false;
        }

        return true;
}

static inline bool check_file_record(const struct MFT_REC *rec,
                                     const struct MFT_REC *rec2,
                                     struct ntfs_sb_info *sbi)
{
        const struct ATTRIB *attr;
        u16 fo = le16_to_cpu(rec->rhdr.fix_off);
        u16 fn = le16_to_cpu(rec->rhdr.fix_num);
        u16 ao = le16_to_cpu(rec->attr_off);
        u32 rs = sbi->record_size;

        /* Check the file record header for consistency. */
        if (rec->rhdr.sign != NTFS_FILE_SIGNATURE ||
            fo > (SECTOR_SIZE - ((rs >> SECTOR_SHIFT) + 1) * sizeof(short)) ||
            (fn - 1) * SECTOR_SIZE != rs || ao < MFTRECORD_FIXUP_OFFSET_1 ||
            ao > sbi->record_size - SIZEOF_RESIDENT || !is_rec_inuse(rec) ||
            le32_to_cpu(rec->total) != rs) {
                return false;
        }

        /* Loop to check all of the attributes. */
        for (attr = Add2Ptr(rec, ao); attr->type != ATTR_END;
             attr = Add2Ptr(attr, le32_to_cpu(attr->size))) {
                if (check_attr(rec, attr, sbi))
                        continue;
                return false;
        }

        return true;
}

static inline int check_lsn(const struct NTFS_RECORD_HEADER *hdr,
                            const u64 *rlsn)
{
        u64 lsn;

        if (!rlsn)
                return true;

        lsn = le64_to_cpu(hdr->lsn);

        if (hdr->sign == NTFS_HOLE_SIGNATURE)
                return false;

        if (*rlsn > lsn)
                return true;

        return false;
}

static inline bool check_if_attr(const struct MFT_REC *rec,
                                 const struct LOG_REC_HDR *lrh)
{
        u16 ro = le16_to_cpu(lrh->record_off);
        u16 o = le16_to_cpu(rec->attr_off);
        const struct ATTRIB *attr = Add2Ptr(rec, o);

        while (o < ro) {
                u32 asize;

                if (attr->type == ATTR_END)
                        break;

                asize = le32_to_cpu(attr->size);
                if (!asize)
                        break;

                o += asize;
                attr = Add2Ptr(attr, asize);
        }

        return o == ro;
}

static inline bool check_if_index_root(const struct MFT_REC *rec,
                                       const struct LOG_REC_HDR *lrh)
{
        u16 ro = le16_to_cpu(lrh->record_off);
        u16 o = le16_to_cpu(rec->attr_off);
        const struct ATTRIB *attr = Add2Ptr(rec, o);

        while (o < ro) {
                u32 asize;

                if (attr->type == ATTR_END)
                        break;

                asize = le32_to_cpu(attr->size);
                if (!asize)
                        break;

                o += asize;
                attr = Add2Ptr(attr, asize);
        }

        return o == ro && attr->type == ATTR_ROOT;
}

static inline bool check_if_root_index(const struct ATTRIB *attr,
                                       const struct INDEX_HDR *hdr,
                                       const struct LOG_REC_HDR *lrh)
{
        u16 ao = le16_to_cpu(lrh->attr_off);
        u32 de_off = le32_to_cpu(hdr->de_off);
        u32 o = PtrOffset(attr, hdr) + de_off;
        const struct NTFS_DE *e = Add2Ptr(hdr, de_off);
        u32 asize = le32_to_cpu(attr->size);

        while (o < ao) {
                u16 esize;

                if (o >= asize)
                        break;

                esize = le16_to_cpu(e->size);
                if (!esize)
                        break;

                o += esize;
                e = Add2Ptr(e, esize);
        }

        return o == ao;
}

static inline bool check_if_alloc_index(const struct INDEX_HDR *hdr,
                                        u32 attr_off)
{
        u32 de_off = le32_to_cpu(hdr->de_off);
        u32 o = offsetof(struct INDEX_BUFFER, ihdr) + de_off;
        const struct NTFS_DE *e = Add2Ptr(hdr, de_off);
        u32 used = le32_to_cpu(hdr->used);

        while (o < attr_off) {
                u16 esize;

                if (de_off >= used)
                        break;

                esize = le16_to_cpu(e->size);
                if (!esize)
                        break;

                o += esize;
                de_off += esize;
                e = Add2Ptr(e, esize);
        }

        return o == attr_off;
}

static inline void change_attr_size(struct MFT_REC *rec, struct ATTRIB *attr,
                                    u32 nsize)
{
        u32 asize = le32_to_cpu(attr->size);
        int dsize = nsize - asize;
        u8 *next = Add2Ptr(attr, asize);
        u32 used = le32_to_cpu(rec->used);

        memmove(Add2Ptr(attr, nsize), next, used - PtrOffset(rec, next));

        rec->used = cpu_to_le32(used + dsize);
        attr->size = cpu_to_le32(nsize);
}

struct OpenAttr {
        struct ATTRIB *attr;
        struct runs_tree *run1;
        struct runs_tree run0;
        struct ntfs_inode *ni;
        // CLST rno;
};

/*
 * cmp_type_and_name
 *
 * Return: 0 if 'attr' has the same type and name.
 */
static inline int cmp_type_and_name(const struct ATTRIB *a1,
                                    const struct ATTRIB *a2)
{
        return a1->type != a2->type || a1->name_len != a2->name_len ||
               (a1->name_len && memcmp(attr_name(a1), attr_name(a2),
                                       a1->name_len * sizeof(short)));
}

static struct OpenAttr *find_loaded_attr(struct ntfs_log *log,
                                         const struct ATTRIB *attr, CLST rno)
{
        struct OPEN_ATTR_ENRTY *oe = NULL;

        while ((oe = enum_rstbl(log->open_attr_tbl, oe))) {
                struct OpenAttr *op_attr;

                if (ino_get(&oe->ref) != rno)
                        continue;

                op_attr = (struct OpenAttr *)oe->ptr;
                if (!cmp_type_and_name(op_attr->attr, attr))
                        return op_attr;
        }
        return NULL;
}

static struct ATTRIB *attr_create_nonres_log(struct ntfs_sb_info *sbi,
                                             enum ATTR_TYPE type, u64 size,
                                             const u16 *name, size_t name_len,
                                             __le16 flags)
{
        struct ATTRIB *attr;
        u32 name_size = ALIGN(name_len * sizeof(short), 8);
        bool is_ext = flags & (ATTR_FLAG_COMPRESSED | ATTR_FLAG_SPARSED);
        u32 asize = name_size +
                    (is_ext ? SIZEOF_NONRESIDENT_EX : SIZEOF_NONRESIDENT);

        attr = kzalloc(asize, GFP_NOFS);
        if (!attr)
                return NULL;

        attr->type = type;
        attr->size = cpu_to_le32(asize);