[linux-flexiantxendom0-3.2.10.git] / fs / ntfs / super.c

/*
 * super.c - NTFS kernel super block handling. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2001-2003 Anton Altaparmakov
 * Copyright (c) 2001,2002 Richard Russon
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be 
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty 
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS 
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/stddef.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/blkdev.h>       /* For bdev_hardsect_size(). */
#include <linux/backing-dev.h>
#include <linux/buffer_head.h>
#include <linux/vfs.h>

#include "ntfs.h"
#include "sysctl.h"

/* Number of mounted file systems which have compression enabled. */
static unsigned long ntfs_nr_compression_users = 0;

/* Error constants/strings used in inode.c::ntfs_show_options(). */
typedef enum {
        /* One of these must be present, default is ON_ERRORS_CONTINUE. */
        ON_ERRORS_PANIC                 = 0x01,
        ON_ERRORS_REMOUNT_RO            = 0x02,
        ON_ERRORS_CONTINUE              = 0x04,
        /* Optional, can be combined with any of the above. */
        ON_ERRORS_RECOVER               = 0x10,
} ON_ERRORS_ACTIONS;

const option_t on_errors_arr[] = {
        { ON_ERRORS_PANIC,      "panic" },
        { ON_ERRORS_REMOUNT_RO, "remount-ro", },
        { ON_ERRORS_CONTINUE,   "continue", },
        { ON_ERRORS_RECOVER,    "recover" },
        { 0,                    NULL }
};

/**
 * simple_getbool -
 *
 * Copied from old ntfs driver (which copied from vfat driver).
 */
static int simple_getbool(char *s, BOOL *setval)
{
        if (s) {
                if (!strcmp(s, "1") || !strcmp(s, "yes") || !strcmp(s, "true"))
                        *setval = TRUE;
                else if (!strcmp(s, "0") || !strcmp(s, "no") ||
                                                        !strcmp(s, "false"))
                        *setval = FALSE;
                else
                        return 0;
        } else
                *setval = TRUE;
        return 1;
}

/**
 * parse_options - parse the (re)mount options
 * @vol:        ntfs volume
 * @opt:        string containing the (re)mount options
 *
 * Parse the recognized options in @opt for the ntfs volume described by @vol.
 */
static BOOL parse_options(ntfs_volume *vol, char *opt)
{
        char *p, *v, *ov;
        static char *utf8 = "utf8";
        int errors = 0, sloppy = 0;
        uid_t uid = (uid_t)-1;
        gid_t gid = (gid_t)-1;
        mode_t fmask = (mode_t)-1, dmask = (mode_t)-1;
        int mft_zone_multiplier = -1, on_errors = -1;
        int show_sys_files = -1, case_sensitive = -1;
        struct nls_table *nls_map = NULL, *old_nls;

        /* I am lazy... (-8 */
#define NTFS_GETOPT_WITH_DEFAULT(option, variable, default_value)       \
        if (!strcmp(p, option)) {                                       \
                if (!v || !*v)                                          \
                        variable = default_value;                       \
                else {                                                  \
                        variable = simple_strtoul(ov = v, &v, 0);       \
                        if (*v)                                         \
                                goto needs_val;                         \
                }                                                       \
        } 
#define NTFS_GETOPT(option, variable)                                   \
        if (!strcmp(p, option)) {                                       \
                if (!v || !*v)                                          \
                        goto needs_arg;                                 \
                variable = simple_strtoul(ov = v, &v, 0);               \
                if (*v)                                                 \
                        goto needs_val;                                 \
        } 
#define NTFS_GETOPT_BOOL(option, variable)                              \
        if (!strcmp(p, option)) {                                       \
                BOOL val;                                               \
                if (!simple_getbool(v, &val))                           \
                        goto needs_bool;                                \
                variable = val;                                         \
        } 
#define NTFS_GETOPT_OPTIONS_ARRAY(option, variable, opt_array)          \
        if (!strcmp(p, option)) {                                       \
                int _i;                                                 \
                if (!v || !*v)                                          \
                        goto needs_arg;                                 \
                ov = v;                                                 \
                if (variable == -1)                                     \
                        variable = 0;                                   \
                for (_i = 0; opt_array[_i].str && *opt_array[_i].str; _i++) \
                        if (!strcmp(opt_array[_i].str, v)) {            \
                                variable |= opt_array[_i].val;          \
                                break;                                  \
                        }                                               \
                if (!opt_array[_i].str || !*opt_array[_i].str)          \
                        goto needs_val;                                 \
        }
        if (!opt || !*opt)
                goto no_mount_options;
        ntfs_debug("Entering with mount options string: %s", opt);
        while ((p = strsep(&opt, ","))) {
                if ((v = strchr(p, '=')))
                        *v++ = '\0';
                NTFS_GETOPT("uid", uid)
                else NTFS_GETOPT("gid", gid)
                else NTFS_GETOPT("umask", fmask = dmask)
                else NTFS_GETOPT("fmask", fmask)
                else NTFS_GETOPT("dmask", dmask)
                else NTFS_GETOPT("mft_zone_multiplier", mft_zone_multiplier)
                else NTFS_GETOPT_WITH_DEFAULT("sloppy", sloppy, TRUE)
                else NTFS_GETOPT_BOOL("show_sys_files", show_sys_files)
                else NTFS_GETOPT_BOOL("case_sensitive", case_sensitive)
                else NTFS_GETOPT_OPTIONS_ARRAY("errors", on_errors,
                                on_errors_arr)
                else if (!strcmp(p, "posix") || !strcmp(p, "show_inodes"))
                        ntfs_warning(vol->sb, "Ignoring obsolete option %s.",
                                        p);
                else if (!strcmp(p, "nls") || !strcmp(p, "iocharset")) {
                        if (!strcmp(p, "iocharset"))
                                ntfs_warning(vol->sb, "Option iocharset is "
                                                "deprecated. Please use "
                                                "option nls=<charsetname> in "
                                                "the future.");
                        if (!v || !*v)
                                goto needs_arg;
use_utf8:
                        old_nls = nls_map;
                        nls_map = load_nls(v);
                        if (!nls_map) {
                                if (!old_nls) {
                                        ntfs_error(vol->sb, "NLS character set "
                                                        "%s not found.", v);
                                        return FALSE;
                                }
                                ntfs_error(vol->sb, "NLS character set %s not "
                                                "found. Using previous one %s.",
                                                v, old_nls->charset);
                                nls_map = old_nls;
                        } else /* nls_map */ {
                                if (old_nls)
                                        unload_nls(old_nls);
                        }
                } else if (!strcmp(p, "utf8")) {
                        BOOL val = FALSE;
                        ntfs_warning(vol->sb, "Option utf8 is no longer "
                                   "supported, using option nls=utf8. Please "
                                   "use option nls=utf8 in the future and "
                                   "make sure utf8 is compiled either as a "
                                   "module or into the kernel.");
                        if (!v || !*v)
                                val = TRUE;
                        else if (!simple_getbool(v, &val))
                                goto needs_bool;
                        if (val) {
                                v = utf8;
                                goto use_utf8;
                        }
                } else {
                        ntfs_error(vol->sb, "Unrecognized mount option %s.", p);
                        if (errors < INT_MAX)
                                errors++;
                }
#undef NTFS_GETOPT_OPTIONS_ARRAY
#undef NTFS_GETOPT_BOOL
#undef NTFS_GETOPT
#undef NTFS_GETOPT_WITH_DEFAULT
        }
no_mount_options:
        if (errors && !sloppy)
                return FALSE;
        if (sloppy)
                ntfs_warning(vol->sb, "Sloppy option given. Ignoring "
                                "unrecognized mount option(s) and continuing.");
        /* Keep this first! */
        if (on_errors != -1) {
                if (!on_errors) {
                        ntfs_error(vol->sb, "Invalid errors option argument "
                                        "or bug in options parser.");
                        return FALSE;
                }
        }
        if (nls_map) {
                if (vol->nls_map && vol->nls_map != nls_map) {
                        ntfs_error(vol->sb, "Cannot change NLS character set "
                                        "on remount.");
                        return FALSE;
                } /* else (!vol->nls_map) */
                ntfs_debug("Using NLS character set %s.", nls_map->charset);
                vol->nls_map = nls_map;
        } else /* (!nls_map) */ {
                if (!vol->nls_map) {
                        vol->nls_map = load_nls_default();
                        if (!vol->nls_map) {
                                ntfs_error(vol->sb, "Failed to load default "
                                                "NLS character set.");
                                return FALSE;
                        }
                        ntfs_debug("Using default NLS character set (%s).",
                                        vol->nls_map->charset);
                }
        }
        if (mft_zone_multiplier != -1) {
                if (vol->mft_zone_multiplier && vol->mft_zone_multiplier !=
                                mft_zone_multiplier) {
                        ntfs_error(vol->sb, "Cannot change mft_zone_multiplier "
                                        "on remount.");
                        return FALSE;
                }
                if (mft_zone_multiplier < 1 || mft_zone_multiplier > 4) {
                        ntfs_error(vol->sb, "Invalid mft_zone_multiplier. "
                                        "Using default value, i.e. 1.");
                        mft_zone_multiplier = 1;
                }
                vol->mft_zone_multiplier = mft_zone_multiplier;
        }
        if (!vol->mft_zone_multiplier)
                vol->mft_zone_multiplier = 1;
        if (on_errors != -1)
                vol->on_errors = on_errors;
        if (!vol->on_errors || vol->on_errors == ON_ERRORS_RECOVER)
                vol->on_errors |= ON_ERRORS_CONTINUE;
        if (uid != (uid_t)-1)
                vol->uid = uid;
        if (gid != (gid_t)-1)
                vol->gid = gid;
        if (fmask != (mode_t)-1)
                vol->fmask = fmask;
        if (dmask != (mode_t)-1)
                vol->dmask = dmask;
        if (show_sys_files != -1) {
                if (show_sys_files)
                        NVolSetShowSystemFiles(vol);
                else
                        NVolClearShowSystemFiles(vol);
        }
        if (case_sensitive != -1) {
                if (case_sensitive)
                        NVolSetCaseSensitive(vol);
                else
                        NVolClearCaseSensitive(vol);
        }
        return TRUE;
needs_arg:
        ntfs_error(vol->sb, "The %s option requires an argument.", p);
        return FALSE;
needs_bool:
        ntfs_error(vol->sb, "The %s option requires a boolean argument.", p);
        return FALSE;
needs_val:
        ntfs_error(vol->sb, "Invalid %s option argument: %s", p, ov);
        return FALSE;
}

/**
 * ntfs_remount - change the mount options of a mounted ntfs filesystem
 * @sb:         superblock of mounted ntfs filesystem
 * @flags:      remount flags
 * @opt:        remount options string
 *
 * Change the mount options of an already mounted ntfs filesystem.
 *
 * NOTE: The VFS set the @sb->s_flags remount flags to @flags after
 * ntfs_remount() returns successfully (i.e. returns 0). Otherwise,
 * @sb->s_flags are not changed.
 */
static int ntfs_remount(struct super_block *sb, int *flags, char *opt)
{
        ntfs_volume *vol = NTFS_SB(sb);

        ntfs_debug("Entering with remount options string: %s", opt);

#ifndef NTFS_RW
        /* For read-only compiled driver, enforce all read-only flags. */
        *flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
#else
        /*
         * For the read-write compiled driver, if we are remounting read-write,
         * make sure there aren't any volume errors.
         */
        if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
                if (NVolErrors(vol)) {
                        ntfs_error(sb, "Volume has errors and is read-only."
                                        "Cannot remount read-write.");
                        return -EROFS;
                }
        }
#endif

        // FIXME/TODO: If left like this we will have problems with rw->ro and
        // ro->rw, as well as with sync->async and vice versa remounts.
        // Note: The VFS already checks that there are no pending deletes and
        // no open files for writing. So we only need to worry about dirty
        // inode pages and dirty system files (which include dirty inodes).
        // Either handle by flushing the whole volume NOW or by having the
        // write routines work on MS_RDONLY fs and guarantee we don't mark
        // anything as dirty if MS_RDONLY is set. That way the dirty data
        // would get flushed but no new dirty data would appear. This is
        // probably best but we need to be careful not to mark anything dirty
        // or the MS_RDONLY will be leaking writes.

        // TODO: Deal with *flags.

        if (!parse_options(vol, opt))
                return -EINVAL;

        return 0;
}

/**
 * is_boot_sector_ntfs - check whether a boot sector is a valid NTFS boot sector
 * @sb:         Super block of the device to which @b belongs.
 * @b:          Boot sector of device @sb to check.
 * @silent:     If TRUE, all output will be silenced.
 *
 * is_boot_sector_ntfs() checks whether the boot sector @b is a valid NTFS boot
 * sector. Returns TRUE if it is valid and FALSE if not.
 *
 * @sb is only needed for warning/error output, i.e. it can be NULL when silent
 * is TRUE.
 */
static BOOL is_boot_sector_ntfs(const struct super_block *sb,
                const NTFS_BOOT_SECTOR *b, const BOOL silent)
{
        /*
         * Check that checksum == sum of u32 values from b to the checksum
         * field. If checksum is zero, no checking is done.
         */
        if ((void*)b < (void*)&b->checksum && b->checksum) {
                u32 i, *u;
                for (i = 0, u = (u32*)b; u < (u32*)(&b->checksum); ++u)
                        i += le32_to_cpup(u);
                if (le32_to_cpu(b->checksum) != i)
                        goto not_ntfs;
        }
        /* Check OEMidentifier is "NTFS    " */
        if (b->oem_id != magicNTFS)
                goto not_ntfs;
        /* Check bytes per sector value is between 256 and 4096. */
        if (le16_to_cpu(b->bpb.bytes_per_sector) <  0x100 ||
                        le16_to_cpu(b->bpb.bytes_per_sector) > 0x1000)
                goto not_ntfs;
        /* Check sectors per cluster value is valid. */
        switch (b->bpb.sectors_per_cluster) {
        case 1: case 2: case 4: case 8: case 16: case 32: case 64: case 128:
                break;
        default:
                goto not_ntfs;
        }
        /* Check the cluster size is not above 65536 bytes. */
        if ((u32)le16_to_cpu(b->bpb.bytes_per_sector) *
                        b->bpb.sectors_per_cluster > 0x10000)
                goto not_ntfs;
        /* Check reserved/unused fields are really zero. */
        if (le16_to_cpu(b->bpb.reserved_sectors) ||
                        le16_to_cpu(b->bpb.root_entries) ||
                        le16_to_cpu(b->bpb.sectors) ||
                        le16_to_cpu(b->bpb.sectors_per_fat) ||
                        le32_to_cpu(b->bpb.large_sectors) || b->bpb.fats)
                goto not_ntfs;
        /* Check clusters per file mft record value is valid. */
        if ((u8)b->clusters_per_mft_record < 0xe1 || 
                        (u8)b->clusters_per_mft_record > 0xf7)
                switch (b->clusters_per_mft_record) {
                case 1: case 2: case 4: case 8: case 16: case 32: case 64:
                        break;
                default:
                        goto not_ntfs;
                }
        /* Check clusters per index block value is valid. */
        if ((u8)b->clusters_per_index_record < 0xe1 || 
                        (u8)b->clusters_per_index_record > 0xf7)
                switch (b->clusters_per_index_record) {
                case 1: case 2: case 4: case 8: case 16: case 32: case 64:
                        break;
                default:
                        goto not_ntfs;
                }
        /*
         * Check for valid end of sector marker. We will work without it, but
         * many BIOSes will refuse to boot from a bootsector if the magic is
         * incorrect, so we emit a warning.
         */
        if (!silent && b->end_of_sector_marker != cpu_to_le16(0xaa55))
                ntfs_warning(sb, "Invalid end of sector marker.");
        return TRUE;
not_ntfs:
        return FALSE;
}

/**
 * read_ntfs_boot_sector - read the NTFS boot sector of a device
 * @sb:         super block of device to read the boot sector from
 * @silent:     if true, suppress all output
 *
 * Reads the boot sector from the device and validates it. If that fails, tries
 * to read the backup boot sector, first from the end of the device a-la NT4 and
 * later and then from the middle of the device a-la NT3.51 and before.
 *
 * If a valid boot sector is found but it is not the primary boot sector, we
 * repair the primary boot sector silently (unless the device is read-only or
 * the primary boot sector is not accessible).
 *
 * NOTE: To call this function, @sb must have the fields s_dev, the ntfs super
 * block (u.ntfs_sb), nr_blocks and the device flags (s_flags) initialized
 * to their respective values.
 *
 * Return the unlocked buffer head containing the boot sector or NULL on error.
 */
static struct buffer_head *read_ntfs_boot_sector(struct super_block *sb,
                const int silent)
{
        const char *read_err_str = "Unable to read %s boot sector.";
        struct buffer_head *bh_primary, *bh_backup;
        long nr_blocks = NTFS_SB(sb)->nr_blocks;

        /* Try to read primary boot sector. */
        if ((bh_primary = sb_bread(sb, 0))) {
                if (is_boot_sector_ntfs(sb, (NTFS_BOOT_SECTOR*)
                                bh_primary->b_data, silent))
                        return bh_primary;
                if (!silent)
                        ntfs_error(sb, "Primary boot sector is invalid.");
        } else if (!silent)
                ntfs_error(sb, read_err_str, "primary");
        if (!(NTFS_SB(sb)->on_errors & ON_ERRORS_RECOVER)) {
                if (bh_primary)
                        brelse(bh_primary);
                if (!silent)
                        ntfs_error(sb, "Mount option errors=recover not used. "
                                        "Aborting without trying to recover.");
                return NULL;
        }
        /* Try to read NT4+ backup boot sector. */
        if ((bh_backup = sb_bread(sb, nr_blocks - 1))) {
                if (is_boot_sector_ntfs(sb, (NTFS_BOOT_SECTOR*)
                                bh_backup->b_data, silent))
                        goto hotfix_primary_boot_sector;
                brelse(bh_backup);
        } else if (!silent)
                ntfs_error(sb, read_err_str, "backup");
        /* Try to read NT3.51- backup boot sector. */
        if ((bh_backup = sb_bread(sb, nr_blocks >> 1))) {
                if (is_boot_sector_ntfs(sb, (NTFS_BOOT_SECTOR*)
                                bh_backup->b_data, silent))
                        goto hotfix_primary_boot_sector;
                if (!silent)
                        ntfs_error(sb, "Could not find a valid backup boot "
                                        "sector.");
                brelse(bh_backup);
        } else if (!silent)
                ntfs_error(sb, read_err_str, "backup");
        /* We failed. Cleanup and return. */
        if (bh_primary)
                brelse(bh_primary);
        return NULL;
hotfix_primary_boot_sector:
        if (bh_primary) {
                /*
                 * If we managed to read sector zero and the volume is not
                 * read-only, copy the found, valid backup boot sector to the
                 * primary boot sector.
                 */
                if (!(sb->s_flags & MS_RDONLY)) {
                        ntfs_warning(sb, "Hot-fix: Recovering invalid primary "
                                        "boot sector from backup copy.");
                        memcpy(bh_primary->b_data, bh_backup->b_data,
                                        sb->s_blocksize);
                        mark_buffer_dirty(bh_primary);
                        sync_dirty_buffer(bh_primary);
                        if (buffer_uptodate(bh_primary)) {
                                brelse(bh_backup);
                                return bh_primary;
                        }
                        ntfs_error(sb, "Hot-fix: Device write error while "
                                        "recovering primary boot sector.");
                } else {
                        ntfs_warning(sb, "Hot-fix: Recovery of primary boot "
                                        "sector failed: Read-only mount.");
                }
                brelse(bh_primary);
        }
        ntfs_warning(sb, "Using backup boot sector.");
        return bh_backup;
}

/**
 * parse_ntfs_boot_sector - parse the boot sector and store the data in @vol
 * @vol:        volume structure to initialise with data from boot sector
 * @b:          boot sector to parse
 * 
 * Parse the ntfs boot sector @b and store all imporant information therein in
 * the ntfs super block @vol. Return TRUE on success and FALSE on error.
 */
static BOOL parse_ntfs_boot_sector(ntfs_volume *vol, const NTFS_BOOT_SECTOR *b)
{
        unsigned int sectors_per_cluster_bits, nr_hidden_sects;
        int clusters_per_mft_record, clusters_per_index_record;
        s64 ll;

        vol->sector_size = le16_to_cpu(b->bpb.bytes_per_sector);
        vol->sector_size_bits = ffs(vol->sector_size) - 1;
        ntfs_debug("vol->sector_size = %i (0x%x)", vol->sector_size,
                        vol->sector_size);
        ntfs_debug("vol->sector_size_bits = %i (0x%x)", vol->sector_size_bits,
                        vol->sector_size_bits);
        if (vol->sector_size != vol->sb->s_blocksize)
                ntfs_warning(vol->sb, "The boot sector indicates a sector size "
                                "different from the device sector size.");
        ntfs_debug("sectors_per_cluster = 0x%x", b->bpb.sectors_per_cluster);
        sectors_per_cluster_bits = ffs(b->bpb.sectors_per_cluster) - 1;
        ntfs_debug("sectors_per_cluster_bits = 0x%x",
                        sectors_per_cluster_bits);
        nr_hidden_sects = le32_to_cpu(b->bpb.hidden_sectors);
        ntfs_debug("number of hidden sectors = 0x%x", nr_hidden_sects);
        vol->cluster_size = vol->sector_size << sectors_per_cluster_bits;
        vol->cluster_size_mask = vol->cluster_size - 1;
        vol->cluster_size_bits = ffs(vol->cluster_size) - 1;
        ntfs_debug("vol->cluster_size = %i (0x%x)", vol->cluster_size,
                        vol->cluster_size);
        ntfs_debug("vol->cluster_size_mask = 0x%x", vol->cluster_size_mask);
        ntfs_debug("vol->cluster_size_bits = %i (0x%x)",
                        vol->cluster_size_bits, vol->cluster_size_bits);
        if (vol->sector_size > vol->cluster_size) {
                ntfs_error(vol->sb, "Sector sizes above the cluster size are "
                                "not supported. Sorry.");
                return FALSE;
        }
        if (vol->sb->s_blocksize > vol->cluster_size) {
                ntfs_error(vol->sb, "Cluster sizes smaller than the device "
                                "sector size are not supported. Sorry.");
                return FALSE;
        }
        clusters_per_mft_record = b->clusters_per_mft_record;
        ntfs_debug("clusters_per_mft_record = %i (0x%x)",
                        clusters_per_mft_record, clusters_per_mft_record);
        if (clusters_per_mft_record > 0)
                vol->mft_record_size = vol->cluster_size <<
                                (ffs(clusters_per_mft_record) - 1);
        else
                /*
                 * When mft_record_size < cluster_size, clusters_per_mft_record
                 * = -log2(mft_record_size) bytes. mft_record_size normaly is
                 * 1024 bytes, which is encoded as 0xF6 (-10 in decimal).
                 */
                vol->mft_record_size = 1 << -clusters_per_mft_record;
        vol->mft_record_size_mask = vol->mft_record_size - 1;
        vol->mft_record_size_bits = ffs(vol->mft_record_size) - 1;
        ntfs_debug("vol->mft_record_size = %i (0x%x)", vol->mft_record_size,
                        vol->mft_record_size);
        ntfs_debug("vol->mft_record_size_mask = 0x%x",
                        vol->mft_record_size_mask);
        ntfs_debug("vol->mft_record_size_bits = %i (0x%x)",
                        vol->mft_record_size_bits, vol->mft_record_size_bits); 
        clusters_per_index_record = b->clusters_per_index_record;
        ntfs_debug("clusters_per_index_record = %i (0x%x)",
                        clusters_per_index_record, clusters_per_index_record); 
        if (clusters_per_index_record > 0)
                vol->index_record_size = vol->cluster_size <<
                                (ffs(clusters_per_index_record) - 1);
        else
                /*
                 * When index_record_size < cluster_size,
                 * clusters_per_index_record = -log2(index_record_size) bytes.
                 * index_record_size normaly equals 4096 bytes, which is
                 * encoded as 0xF4 (-12 in decimal).
                 */
                vol->index_record_size = 1 << -clusters_per_index_record;
        vol->index_record_size_mask = vol->index_record_size - 1;
        vol->index_record_size_bits = ffs(vol->index_record_size) - 1;
        ntfs_debug("vol->index_record_size = %i (0x%x)",
                        vol->index_record_size, vol->index_record_size); 
        ntfs_debug("vol->index_record_size_mask = 0x%x",
                        vol->index_record_size_mask);
        ntfs_debug("vol->index_record_size_bits = %i (0x%x)",
                        vol->index_record_size_bits,
                        vol->index_record_size_bits);
        /*
         * Get the size of the volume in clusters and check for 64-bit-ness.
         * Windows currently only uses 32 bits to save the clusters so we do
         * the same as it is much faster on 32-bit CPUs.
         */
        ll = sle64_to_cpu(b->number_of_sectors) >> sectors_per_cluster_bits;
        if ((u64)ll >= 1ULL << 32) {
                ntfs_error(vol->sb, "Cannot handle 64-bit clusters. Sorry.");
                return FALSE;
        }
        vol->nr_clusters = ll;
        ntfs_debug("vol->nr_clusters = 0x%Lx", (long long)vol->nr_clusters);
        /*
         * On an architecture where unsigned long is 32-bits, we restrict the
         * volume size to 2TiB (2^41). On a 64-bit architecture, the compiler
         * will hopefully optimize the whole check away.
         */
        if (sizeof(unsigned long) < 8) {
                if ((ll << vol->cluster_size_bits) >= (1ULL << 41)) {
                        ntfs_error(vol->sb, "Volume size (%LuTiB) is too large "
                                        "for this architecture. Maximim "
                                        "supported is 2TiB. Sorry.",
                                        ll >> (40 - vol->cluster_size_bits));
                        return FALSE;
                }
        }
        ll = sle64_to_cpu(b->mft_lcn);
        if (ll >= vol->nr_clusters) {
                ntfs_error(vol->sb, "MFT LCN is beyond end of volume. Weird.");
                return FALSE;
        }
        vol->mft_lcn = ll;
        ntfs_debug("vol->mft_lcn = 0x%Lx", (long long)vol->mft_lcn);
        ll = sle64_to_cpu(b->mftmirr_lcn);
        if (ll >= vol->nr_clusters) {
                ntfs_error(vol->sb, "MFTMirr LCN is beyond end of volume. "
                                "Weird.");
                return FALSE;
        }
        vol->mftmirr_lcn = ll;
        ntfs_debug("vol->mftmirr_lcn = 0x%Lx", (long long)vol->mftmirr_lcn);
        vol->serial_no = le64_to_cpu(b->volume_serial_number);
        ntfs_debug("vol->serial_no = 0x%Lx",
                        (unsigned long long)vol->serial_no);
        /*
         * Determine MFT zone size. This is not strictly the right place to do
         * this, but I am too lazy to create a function especially for it...
         */
        vol->mft_zone_end = vol->nr_clusters;
        switch (vol->mft_zone_multiplier) {  /* % of volume size in clusters */
        case 4:
                vol->mft_zone_end = vol->mft_zone_end >> 1;     /* 50%   */
                break;
        case 3:
                vol->mft_zone_end = (vol->mft_zone_end +
                                (vol->mft_zone_end >> 1)) >> 2; /* 37.5% */
                break;
        case 2:
                vol->mft_zone_end = vol->mft_zone_end >> 2;     /* 25%   */
                break;
        default:
                vol->mft_zone_multiplier = 1;
                /* Fall through into case 1. */
        case 1:
                vol->mft_zone_end = vol->mft_zone_end >> 3;     /* 12.5% */
                break;
        }
        ntfs_debug("vol->mft_zone_multiplier = 0x%x",
                        vol->mft_zone_multiplier);
        vol->mft_zone_start = vol->mft_lcn;
        vol->mft_zone_end += vol->mft_lcn;
        ntfs_debug("vol->mft_zone_start = 0x%Lx",
                        (long long)vol->mft_zone_start);
        ntfs_debug("vol->mft_zone_end = 0x%Lx", (long long)vol->mft_zone_end);
        /* And another misplaced defaults setting. */
        if (!vol->on_errors)
                vol->on_errors = ON_ERRORS_PANIC;
        return TRUE;
}

/**
 * load_and_init_upcase - load the upcase table for an ntfs volume
 * @vol:        ntfs super block describing device whose upcase to load
 *
 * Return TRUE on success or FALSE on error.
 */
static BOOL load_and_init_upcase(ntfs_volume *vol)
{
        struct super_block *sb = vol->sb;
        struct inode *ino;
        struct page *page;
        unsigned long index, max_index;
        unsigned int size;
        int i, max;

        ntfs_debug("Entering.");
        /* Read upcase table and setup vol->upcase and vol->upcase_len. */
        ino = ntfs_iget(sb, FILE_UpCase);
        if (IS_ERR(ino) || is_bad_inode(ino)) {
                if (!IS_ERR(ino))
                        iput(ino);
                goto upcase_failed;
        }
        /*
         * The upcase size must not be above 64k Unicode characters, must not
         * be zero and must be a multiple of sizeof(uchar_t).
         */
        if (!ino->i_size || ino->i_size & (sizeof(uchar_t) - 1) ||
                        ino->i_size > 64ULL * 1024 * sizeof(uchar_t))
                goto iput_upcase_failed;
        vol->upcase = (uchar_t*)ntfs_malloc_nofs(ino->i_size);
        if (!vol->upcase)
                goto iput_upcase_failed;
        index = 0;
        max_index = ino->i_size >> PAGE_CACHE_SHIFT;
        size = PAGE_CACHE_SIZE;
        while (index < max_index) {
                /* Read the upcase table and copy it into the linear buffer. */
read_partial_upcase_page:
                page = ntfs_map_page(ino->i_mapping, index);
                if (IS_ERR(page))
                        goto iput_upcase_failed;
                memcpy((char*)vol->upcase + (index++ << PAGE_CACHE_SHIFT),
                                page_address(page), size);
                ntfs_unmap_page(page);
        };
        if (size == PAGE_CACHE_SIZE) {
                size = ino->i_size & ~PAGE_CACHE_MASK;
                if (size)
                        goto read_partial_upcase_page;
        }
        vol->upcase_len = ino->i_size >> UCHAR_T_SIZE_BITS;
        ntfs_debug("Read %Lu bytes from $UpCase (expected %u bytes).",
                        ino->i_size, 64 * 1024 * sizeof(uchar_t));
        iput(ino);
        down(&ntfs_lock);
        if (!default_upcase) {
                ntfs_debug("Using volume specified $UpCase since default is "
                                "not present.");
                up(&ntfs_lock);
                return TRUE;
        }
        max = default_upcase_len;
        if (max > vol->upcase_len)
                max = vol->upcase_len;
        for (i = 0; i < max; i++)
                if (vol->upcase[i] != default_upcase[i])
                        break;
        if (i == max) {
                ntfs_free(vol->upcase);
                vol->upcase = default_upcase;
                vol->upcase_len = max;
                ntfs_nr_upcase_users++;
                up(&ntfs_lock);
                ntfs_debug("Volume specified $UpCase matches default. Using "
                                "default.");
                return TRUE;
        }
        up(&ntfs_lock);
        ntfs_debug("Using volume specified $UpCase since it does not match "
                        "the default.");
        return TRUE;
iput_upcase_failed:
        iput(ino);
        ntfs_free(vol->upcase);
        vol->upcase = NULL;
upcase_failed:
        down(&ntfs_lock);
        if (default_upcase) {
                vol->upcase = default_upcase;
                vol->upcase_len = default_upcase_len;
                ntfs_nr_upcase_users++;
                up(&ntfs_lock);
                ntfs_error(sb, "Failed to load $UpCase from the volume. Using "
                                "default.");
                return TRUE;
        }
        up(&ntfs_lock);
        ntfs_error(sb, "Failed to initialized upcase table.");
        return FALSE;
}

/**
 * load_system_files - open the system files using normal functions
 * @vol:        ntfs super block describing device whose system files to load
 *
 * Open the system files with normal access functions and complete setting up
 * the ntfs super block @vol.
 *
 * Return TRUE on success or FALSE on error.
 */
static BOOL load_system_files(ntfs_volume *vol)
{
        struct super_block *sb = vol->sb;
        struct inode *tmp_ino;
        MFT_RECORD *m;
        VOLUME_INFORMATION *vi;
        attr_search_context *ctx;

        ntfs_debug("Entering.");

        /* Get mft bitmap attribute inode. */
        vol->mftbmp_ino = ntfs_attr_iget(vol->mft_ino, AT_BITMAP, NULL, 0);
        if (IS_ERR(vol->mftbmp_ino)) {
                ntfs_error(sb, "Failed to load $MFT/$BITMAP attribute.");
                return FALSE;
        }

        /* Get mft mirror inode. */
        vol->mftmirr_ino = ntfs_iget(sb, FILE_MFTMirr);
        if (IS_ERR(vol->mftmirr_ino) || is_bad_inode(vol->mftmirr_ino)) {
                if (!IS_ERR(vol->mftmirr_ino))
                        iput(vol->mftmirr_ino);
                ntfs_error(sb, "Failed to load $MFTMirr.");
                goto iput_mftbmp_err_out;
        }
        // FIXME: Compare mftmirr with mft and repair if appropriate and not
        // a read-only mount.

        /* Read upcase table and setup vol->upcase and vol->upcase_len. */
        if (!load_and_init_upcase(vol))
                goto iput_mirr_err_out;
        /*
         * Get the cluster allocation bitmap inode and verify the size, no
         * need for any locking at this stage as we are already running
         * exclusively as we are mount in progress task.
         */
        vol->lcnbmp_ino = ntfs_iget(sb, FILE_Bitmap);
        if (IS_ERR(vol->lcnbmp_ino) || is_bad_inode(vol->lcnbmp_ino)) {
                if (!IS_ERR(vol->lcnbmp_ino))
                        iput(vol->lcnbmp_ino);
                goto bitmap_failed;
        }
        if ((vol->nr_clusters + 7) >> 3 > vol->lcnbmp_ino->i_size) {
                iput(vol->lcnbmp_ino);
bitmap_failed:
                ntfs_error(sb, "Failed to load $Bitmap.");
                goto iput_mirr_err_out;
        }
        /*
         * Get the volume inode and setup our cache of the volume flags and
         * version.
         */
        vol->vol_ino = ntfs_iget(sb, FILE_Volume);
        if (IS_ERR(vol->vol_ino) || is_bad_inode(vol->vol_ino)) {
                if (!IS_ERR(vol->vol_ino))
                        iput(vol->vol_ino);
volume_failed:
                ntfs_error(sb, "Failed to load $Volume.");
                goto iput_lcnbmp_err_out;
        }
        m = map_mft_record(NTFS_I(vol->vol_ino));
        if (IS_ERR(m)) {
iput_volume_failed:
                iput(vol->vol_ino);
                goto volume_failed;
        }
        if (!(ctx = get_attr_search_ctx(NTFS_I(vol->vol_ino), m))) {
                ntfs_error(sb, "Failed to get attribute search context.");
                goto get_ctx_vol_failed;
        }
        if (!lookup_attr(AT_VOLUME_INFORMATION, NULL, 0, 0, 0, NULL, 0, ctx) ||
                        ctx->attr->non_resident || ctx->attr->flags) {
err_put_vol:
                put_attr_search_ctx(ctx);
get_ctx_vol_failed:
                unmap_mft_record(NTFS_I(vol->vol_ino));
                goto iput_volume_failed;
        }
        vi = (VOLUME_INFORMATION*)((char*)ctx->attr +
                        le16_to_cpu(ctx->attr->data.resident.value_offset));
        /* Some bounds checks. */
        if ((u8*)vi < (u8*)ctx->attr || (u8*)vi +
                        le32_to_cpu(ctx->attr->data.resident.value_length) >
                        (u8*)ctx->attr + le32_to_cpu(ctx->attr->length))
                goto err_put_vol;
        /* Setup volume flags and version. */
        vol->vol_flags = vi->flags;
        vol->major_ver = vi->major_ver;
        vol->minor_ver = vi->minor_ver;
        put_attr_search_ctx(ctx);
        unmap_mft_record(NTFS_I(vol->vol_ino));
        printk(KERN_INFO "NTFS volume version %i.%i.\n", vol->major_ver,
                        vol->minor_ver);
        /*
         * Get the inode for the logfile and empty it if this is a read-write
         * mount.
         */
        tmp_ino = ntfs_iget(sb, FILE_LogFile);
        if (IS_ERR(tmp_ino) || is_bad_inode(tmp_ino)) {
                if (!IS_ERR(tmp_ino))
                        iput(tmp_ino);
                ntfs_error(sb, "Failed to load $LogFile.");
                // FIMXE: We only want to empty the thing so pointless bailing
                // out. Can recover/ignore.
                goto iput_vol_err_out;
        }
        // FIXME: Empty the logfile, but only if not read-only.
        // FIXME: What happens if someone remounts rw? We need to empty the file
        // then. We need a flag to tell us whether we have done it already.
        iput(tmp_ino);
        /*
         * Get the inode for the attribute definitions file and parse the
         * attribute definitions.
         */ 
        tmp_ino = ntfs_iget(sb, FILE_AttrDef);
        if (IS_ERR(tmp_ino) || is_bad_inode(tmp_ino)) {
                if (!IS_ERR(tmp_ino))
                        iput(tmp_ino);
                ntfs_error(sb, "Failed to load $AttrDef.");
                goto iput_vol_err_out;
        }
        // FIXME: Parse the attribute definitions.
        iput(tmp_ino);
        /* Get the root directory inode. */
        vol->root_ino = ntfs_iget(sb, FILE_root);
        if (IS_ERR(vol->root_ino) || is_bad_inode(vol->root_ino)) {
                if (!IS_ERR(vol->root_ino))
                        iput(vol->root_ino);
                ntfs_error(sb, "Failed to load root directory.");
                goto iput_vol_err_out;
        }
        /* If on NTFS versions before 3.0, we are done. */
        if (vol->major_ver < 3)
                return TRUE;
        /* NTFS 3.0+ specific initialization. */
        /* Get the security descriptors inode. */
        vol->secure_ino = ntfs_iget(sb, FILE_Secure);
        if (IS_ERR(vol->secure_ino) || is_bad_inode(vol->secure_ino)) {
                if (!IS_ERR(vol->secure_ino))
                        iput(vol->secure_ino);
                ntfs_error(sb, "Failed to load $Secure.");
                goto iput_root_err_out;
        }
        // FIXME: Initialize security.
        /* Get the extended system files' directory inode. */
        tmp_ino = ntfs_iget(sb, FILE_Extend);
        if (IS_ERR(tmp_ino) || is_bad_inode(tmp_ino)) {
                if (!IS_ERR(tmp_ino))
                        iput(tmp_ino);
                ntfs_error(sb, "Failed to load $Extend.");
                goto iput_sec_err_out;
        }
        // FIXME: Do something. E.g. want to delete the $UsnJrnl if exists.
        // Note we might be doing this at the wrong level; we might want to
        // d_alloc_root() and then do a "normal" open(2) of $Extend\$UsnJrnl
        // rather than using ntfs_iget here, as we don't know the inode number
        // for the files in $Extend directory.
        iput(tmp_ino);
        return TRUE;
iput_sec_err_out:
        iput(vol->secure_ino);
iput_root_err_out:
        iput(vol->root_ino);
iput_vol_err_out:
        iput(vol->vol_ino);
iput_lcnbmp_err_out:
        iput(vol->lcnbmp_ino);
iput_mirr_err_out:
        iput(vol->mftmirr_ino);
iput_mftbmp_err_out:
        iput(vol->mftbmp_ino);
        return FALSE;
}

/**
 * ntfs_put_super - called by the vfs to unmount a volume
 * @vfs_sb:     vfs superblock of volume to unmount
 *
 * ntfs_put_super() is called by the VFS (from fs/super.c::do_umount()) when
 * the volume is being unmounted (umount system call has been invoked) and it
 * releases all inodes and memory belonging to the NTFS specific part of the
 * super block.
 */
static void ntfs_put_super(struct super_block *vfs_sb)
{
        ntfs_volume *vol = NTFS_SB(vfs_sb);

        ntfs_debug("Entering.");

        iput(vol->vol_ino);
        vol->vol_ino = NULL;

        /* NTFS 3.0+ specific clean up. */
        if (vol->major_ver >= 3) {
                if (vol->secure_ino) {
                        iput(vol->secure_ino);
                        vol->secure_ino = NULL;
                }
        }

        iput(vol->root_ino);
        vol->root_ino = NULL;

        down_write(&vol->lcnbmp_lock);
        iput(vol->lcnbmp_ino);
        vol->lcnbmp_ino = NULL;
        up_write(&vol->lcnbmp_lock);

        iput(vol->mftmirr_ino);
        vol->mftmirr_ino = NULL;

        down_write(&vol->mftbmp_lock);
        iput(vol->mftbmp_ino);
        vol->mftbmp_ino = NULL;
        up_write(&vol->mftbmp_lock);

        iput(vol->mft_ino);
        vol->mft_ino = NULL;

        vol->upcase_len = 0;
        /*
         * Decrease the number of mounts and destroy the global default upcase
         * table if necessary. Also decrease the number of upcase users if we
         * are a user.
         */
        down(&ntfs_lock);
        ntfs_nr_mounts--;
        if (vol->upcase == default_upcase) {
                ntfs_nr_upcase_users--;
                vol->upcase = NULL;
        }
        if (!ntfs_nr_upcase_users && default_upcase) {
                ntfs_free(default_upcase);
                default_upcase = NULL;
        }
        if (vol->cluster_size <= 4096 && !--ntfs_nr_compression_users)
                free_compression_buffers();
        up(&ntfs_lock);
        if (vol->upcase) {
                ntfs_free(vol->upcase);
                vol->upcase = NULL;
        }
        if (vol->nls_map) {
                unload_nls(vol->nls_map);
                vol->nls_map = NULL;
        }
        vfs_sb->s_fs_info = NULL;
        kfree(vol);
        return;
}

/**
 * get_nr_free_clusters - return the number of free clusters on a volume
 * @vol:        ntfs volume for which to obtain free cluster count
 *
 * Calculate the number of free clusters on the mounted NTFS volume @vol. We
 * actually calculate the number of clusters in use instead because this
 * allows us to not care about partial pages as these will be just zero filled
 * and hence not be counted as allocated clusters.
 *
 * The only particularity is that clusters beyond the end of the logical ntfs
 * volume will be marked as allocated to prevent errors which means we have to
 * discount those at the end. This is important as the cluster bitmap always
 * has a size in multiples of 8 bytes, i.e. up to 63 clusters could be outside
 * the logical volume and marked in use when they are not as they do not exist.
 *
 * If any pages cannot be read we assume all clusters in the erroring pages are
 * in use. This means we return an underestimate on errors which is better than
 * an overestimate.
 */
static s64 get_nr_free_clusters(ntfs_volume *vol)
{
        s64 nr_free = vol->nr_clusters;
        u32 *kaddr;
        struct address_space *mapping = vol->lcnbmp_ino->i_mapping;
        filler_t *readpage = (filler_t*)mapping->a_ops->readpage;
        struct page *page;
        unsigned long index, max_index;
        unsigned int max_size;

        ntfs_debug("Entering.");
        /* Serialize accesses to the cluster bitmap. */
        down_read(&vol->lcnbmp_lock);
        /*
         * Convert the number of bits into bytes rounded up, then convert into
         * multiples of PAGE_CACHE_SIZE, rounding up so that if we have one
         * full and one partial page max_index = 2.
         */
        max_index = (((vol->nr_clusters + 7) >> 3) + PAGE_CACHE_SIZE - 1) >>
                        PAGE_CACHE_SHIFT;
        /* Use multiples of 4 bytes. */
        max_size = PAGE_CACHE_SIZE >> 2;
        ntfs_debug("Reading $Bitmap, max_index = 0x%lx, max_size = 0x%x.",
                        max_index, max_size);
        for (index = 0UL; index < max_index; index++) {
                unsigned int i;
                /*
                 * Read the page from page cache, getting it from backing store
                 * if necessary, and increment the use count.
                 */
                page = read_cache_page(mapping, index, (filler_t*)readpage,
                                NULL);
                /* Ignore pages which errored synchronously. */
                if (IS_ERR(page)) {
                        ntfs_debug("Sync read_cache_page() error. Skipping "
                                        "page (index 0x%lx).", index);
                        nr_free -= PAGE_CACHE_SIZE * 8;
                        continue;
                }
                wait_on_page_locked(page);
                /* Ignore pages which errored asynchronously. */
                if (!PageUptodate(page)) {
                        ntfs_debug("Async read_cache_page() error. Skipping "
                                        "page (index 0x%lx).", index);
                        page_cache_release(page);
                        nr_free -= PAGE_CACHE_SIZE * 8;
                        continue;
                }
                kaddr = (u32*)kmap_atomic(page, KM_USER0);
                /*
                 * For each 4 bytes, subtract the number of set bits. If this
                 * is the last page and it is partial we don't really care as
                 * it just means we do a little extra work but it won't affect
                 * the result as all out of range bytes are set to zero by
                 * ntfs_readpage().
                 */
                for (i = 0; i < max_size; i++)
                        nr_free -= (s64)hweight32(kaddr[i]);
                kunmap_atomic(kaddr, KM_USER0);
                page_cache_release(page);
        }
        ntfs_debug("Finished reading $Bitmap, last index = 0x%lx.", index - 1);
        /*
         * Fixup for eventual bits outside logical ntfs volume (see function
         * description above).
         */
        if (vol->nr_clusters & 63)
                nr_free += 64 - (vol->nr_clusters & 63);
        up_read(&vol->lcnbmp_lock);
        /* If errors occured we may well have gone below zero, fix this. */
        if (nr_free < 0)
                nr_free = 0;
        ntfs_debug("Exiting.");
        return nr_free;
}

/**
 * __get_nr_free_mft_records - return the number of free inodes on a volume
 * @vol:        ntfs volume for which to obtain free inode count
 *
 * Calculate the number of free mft records (inodes) on the mounted NTFS
 * volume @vol. We actually calculate the number of mft records in use instead
 * because this allows us to not care about partial pages as these will be just
 * zero filled and hence not be counted as allocated mft record.
 *
 * If any pages cannot be read we assume all mft records in the erroring pages
 * are in use. This means we return an underestimate on errors which is better
 * than an overestimate.
 *
 * NOTE: Caller must hold mftbmp_lock rw_semaphore for reading or writing.
 */
static unsigned long __get_nr_free_mft_records(ntfs_volume *vol)
{
        s64 nr_free = vol->nr_mft_records;
        u32 *kaddr;
        struct address_space *mapping = vol->mftbmp_ino->i_mapping;
        filler_t *readpage = (filler_t*)mapping->a_ops->readpage;
        struct page *page;
        unsigned long index, max_index;
        unsigned int max_size;

        ntfs_debug("Entering.");
        /*
         * Convert the number of bits into bytes rounded up, then convert into
         * multiples of PAGE_CACHE_SIZE, rounding up so that if we have one
         * full and one partial page max_index = 2.
         */
        max_index = (((vol->nr_mft_records + 7) >> 3) + PAGE_CACHE_SIZE - 1) >>
                        PAGE_CACHE_SHIFT;
        /* Use multiples of 4 bytes. */
        max_size = PAGE_CACHE_SIZE >> 2;
        ntfs_debug("Reading $MFT/$BITMAP, max_index = 0x%lx, max_size = "
                        "0x%x.", max_index, max_size);
        for (index = 0UL; index < max_index; index++) {
                unsigned int i;
                /*
                 * Read the page from page cache, getting it from backing store
                 * if necessary, and increment the use count.
                 */
                page = read_cache_page(mapping, index, (filler_t*)readpage,
                                NULL);
                /* Ignore pages which errored synchronously. */
                if (IS_ERR(page)) {
                        ntfs_debug("Sync read_cache_page() error. Skipping "
                                        "page (index 0x%lx).", index);
                        nr_free -= PAGE_CACHE_SIZE * 8;
                        continue;
                }
                wait_on_page_locked(page);
                /* Ignore pages which errored asynchronously. */
                if (!PageUptodate(page)) {
                        ntfs_debug("Async read_cache_page() error. Skipping "
                                        "page (index 0x%lx).", index);
                        page_cache_release(page);
                        nr_free -= PAGE_CACHE_SIZE * 8;
                        continue;
                }
                kaddr = (u32*)kmap_atomic(page, KM_USER0);
                /*
                 * For each 4 bytes, subtract the number of set bits. If this
                 * is the last page and it is partial we don't really care as
                 * it just means we do a little extra work but it won't affect
                 * the result as all out of range bytes are set to zero by
                 * ntfs_readpage().
                 */
                for (i = 0; i < max_size; i++)
                        nr_free -= (s64)hweight32(kaddr[i]);
                kunmap_atomic(kaddr, KM_USER0);
                page_cache_release(page);
        }
        ntfs_debug("Finished reading $MFT/$BITMAP, last index = 0x%lx.",
                        index - 1);
        /* If errors occured we may well have gone below zero, fix this. */
        if (nr_free < 0)
                nr_free = 0;
        ntfs_debug("Exiting.");
        return nr_free;
}

/**
 * ntfs_statfs - return information about mounted NTFS volume
 * @sb:         super block of mounted volume
 * @sfs:        statfs structure in which to return the information
 *
 * Return information about the mounted NTFS volume @sb in the statfs structure
 * pointed to by @sfs (this is initialized with zeros before ntfs_statfs is
 * called). We interpret the values to be correct of the moment in time at
 * which we are called. Most values are variable otherwise and this isn't just
 * the free values but the totals as well. For example we can increase the
 * total number of file nodes if we run out and we can keep doing this until
 * there is no more space on the volume left at all.
 *
 * Called from vfs_statfs which is used to handle the statfs, fstatfs, and
 * ustat system calls.
 *
 * Return 0 on success or -errno on error.
 */
static int ntfs_statfs(struct super_block *sb, struct kstatfs *sfs)
{
        ntfs_volume *vol = NTFS_SB(sb);
        s64 size;

        ntfs_debug("Entering.");
        /* Type of filesystem. */
        sfs->f_type   = NTFS_SB_MAGIC;
        /* Optimal transfer block size. */
        sfs->f_bsize  = PAGE_CACHE_SIZE;
        /*
         * Total data blocks in file system in units of f_bsize and since
         * inodes are also stored in data blocs ($MFT is a file) this is just
         * the total clusters.
         */
        sfs->f_blocks = vol->nr_clusters << vol->cluster_size_bits >>
                                PAGE_CACHE_SHIFT;
        /* Free data blocks in file system in units of f_bsize. */
        size          = get_nr_free_clusters(vol) << vol->cluster_size_bits >>
                                PAGE_CACHE_SHIFT;
        if (size < 0LL)
                size = 0LL;
        /* Free blocks avail to non-superuser, same as above on NTFS. */
        sfs->f_bavail = sfs->f_bfree = size;
        /* Serialize accesses to the inode bitmap. */
        down_read(&vol->mftbmp_lock);
        /* Total file nodes in file system (at this moment in time). */
        sfs->f_files  = vol->mft_ino->i_size >> vol->mft_record_size_bits;
        /* Free file nodes in fs (based on current total count). */
        sfs->f_ffree = __get_nr_free_mft_records(vol);
        up_read(&vol->mftbmp_lock);
        /*
         * File system id. This is extremely *nix flavour dependent and even
         * within Linux itself all fs do their own thing. I interpret this to
         * mean a unique id associated with the mounted fs and not the id
         * associated with the file system driver, the latter is already given
         * by the file system type in sfs->f_type. Thus we use the 64-bit
         * volume serial number splitting it into two 32-bit parts. We enter
         * the least significant 32-bits in f_fsid[0] and the most significant
         * 32-bits in f_fsid[1].
         */
        sfs->f_fsid.val[0] = vol->serial_no & 0xffffffff;
        sfs->f_fsid.val[1] = (vol->serial_no >> 32) & 0xffffffff;
        /* Maximum length of filenames. */
        sfs->f_namelen     = NTFS_MAX_NAME_LEN;
        return 0;
}

/**
 * Super operations for mount time when we don't have enough setup to use the
 * proper functions.
 */
struct super_operations ntfs_mount_sops = {
        .alloc_inode    = ntfs_alloc_big_inode,   /* VFS: Allocate new inode. */
        .destroy_inode  = ntfs_destroy_big_inode, /* VFS: Deallocate inode. */
        .read_inode     = ntfs_read_inode_mount,  /* VFS: Load inode from disk,
                                                     called from iget(). */
        .clear_inode    = ntfs_clear_big_inode,   /* VFS: Called when inode is
                                                     removed from memory. */
};

/**
 * The complete super operations.
 */
struct super_operations ntfs_sops = {
        .alloc_inode    = ntfs_alloc_big_inode,   /* VFS: Allocate new inode. */
        .destroy_inode  = ntfs_destroy_big_inode, /* VFS: Deallocate inode. */
        //.dirty_inode  = ntfs_dirty_inode,       /* VFS: Called from
        //                                           __mark_inode_dirty(). */
        //.write_inode  = NULL,           /* VFS: Write dirty inode to disk. */
        .put_inode      = ntfs_put_inode, /* VFS: Called just before the inode
                                             reference count is decreased. */
        //.delete_inode = NULL,           /* VFS: Delete inode from disk. Called
        //                                   when i_count becomes 0 and i_nlink
        //                                   is also 0. */
        .put_super      = ntfs_put_super, /* Syscall: umount. */
        //write_super   = NULL,           /* Flush dirty super block to disk. */
        //write_super_lockfs    = NULL,   /* ? */
        //unlockfs      = NULL,           /* ? */
        .statfs         = ntfs_statfs,    /* Syscall: statfs */
        .remount_fs     = ntfs_remount,   /* Syscall: mount -o remount. */
        .clear_inode    = ntfs_clear_big_inode, /* VFS: Called when an inode is
                                                   removed from memory. */
        //.umount_begin = NULL,              /* Forced umount. */
        .show_options   = ntfs_show_options, /* Show mount options in proc. */
};

/**
 * ntfs_fill_super - mount an ntfs files system
 * @sb:         super block of ntfs file system to mount
 * @opt:        string containing the mount options
 * @silent:     silence error output
 *
 * ntfs_fill_super() is called by the VFS to mount the device described by @sb
 * with the mount otions in @data with the NTFS file system.
 *
 * If @silent is true, remain silent even if errors are detected. This is used
 * during bootup, when the kernel tries to mount the root file system with all
 * registered file systems one after the other until one succeeds. This implies
 * that all file systems except the correct one will quite correctly and
 * expectedly return an error, but nobody wants to see error messages when in
 * fact this is what is supposed to happen.
 *
 * NOTE: @sb->s_flags contains the mount options flags.
 */
static int ntfs_fill_super(struct super_block *sb, void *opt, const int silent)
{
        ntfs_volume *vol;
        struct buffer_head *bh;
        struct inode *tmp_ino;
        int result;

        ntfs_debug("Entering.");
#ifndef NTFS_RW
        sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
#endif
        /* Allocate a new ntfs_volume and place it in sb->s_fs_info. */
        sb->s_fs_info = kmalloc(sizeof(ntfs_volume), GFP_NOFS);
        vol = NTFS_SB(sb);
        if (!vol) {
                if (!silent)
                        ntfs_error(sb, "Allocation of NTFS volume structure "
                                        "failed. Aborting mount...");
                return -ENOMEM;
        }
        /* Initialize ntfs_volume structure. */
        memset(vol, 0, sizeof(ntfs_volume));
        vol->sb = sb;
        vol->upcase = NULL;
        vol->mft_ino = NULL;
        vol->mftbmp_ino = NULL;
        init_rwsem(&vol->mftbmp_lock);
        vol->mftmirr_ino = NULL;
        vol->lcnbmp_ino = NULL;
        init_rwsem(&vol->lcnbmp_lock);
        vol->vol_ino = NULL;
        vol->root_ino = NULL;
        vol->secure_ino = NULL;
        vol->uid = vol->gid = 0;
        vol->flags = 0;
        vol->on_errors = 0;
        vol->mft_zone_multiplier = 0;
        vol->nls_map = NULL;

        /*
         * Default is group and other don't have any access to files or
         * directories while owner has full access. Further, files by default
         * are not executable but directories are of course browseable.
         */
        vol->fmask = 0177;
        vol->dmask = 0077;

        /* Important to get the mount options dealt with now. */
        if (!parse_options(vol, (char*)opt))
                goto err_out_now;

        /*
         * TODO: Fail safety check. In the future we should really be able to
         * cope with this being the case, but for now just bail out.
         */
        if (bdev_hardsect_size(sb->s_bdev) > NTFS_BLOCK_SIZE) {
                if (!silent)
                        ntfs_error(sb, "Device has unsupported hardsect_size.");
                goto err_out_now;
        }

        /* Setup the device access block size to NTFS_BLOCK_SIZE. */
        if (sb_set_blocksize(sb, NTFS_BLOCK_SIZE) != NTFS_BLOCK_SIZE) {
                if (!silent)
                        ntfs_error(sb, "Unable to set block size.");
                goto err_out_now;
        }

        /* Get the size of the device in units of NTFS_BLOCK_SIZE bytes. */
        vol->nr_blocks = sb->s_bdev->bd_inode->i_size >> NTFS_BLOCK_SIZE_BITS;

        /* Read the boot sector and return unlocked buffer head to it. */
        if (!(bh = read_ntfs_boot_sector(sb, silent))) {
                if (!silent)
                        ntfs_error(sb, "Not an NTFS volume.");
                goto err_out_now;
        }
        
        /*
         * Extract the data from the boot sector and setup the ntfs super block
         * using it.
         */
        result = parse_ntfs_boot_sector(vol, (NTFS_BOOT_SECTOR*)bh->b_data);

        brelse(bh);

        if (!result) {
                if (!silent)
                        ntfs_error(sb, "Unsupported NTFS filesystem.");
                goto err_out_now;
        }

        /* 
         * TODO: When we start coping with sector sizes different from
         * NTFS_BLOCK_SIZE, we now probably need to set the blocksize of the
         * device (probably to NTFS_BLOCK_SIZE).
         */

        /* Setup remaining fields in the super block. */
        sb->s_magic = NTFS_SB_MAGIC;

        /*
         * Ntfs allows 63 bits for the file size, i.e. correct would be:
         *      sb->s_maxbytes = ~0ULL >> 1;
         * But the kernel uses a long as the page cache page index which on
         * 32-bit architectures is only 32-bits. MAX_LFS_FILESIZE is kernel
         * defined to the maximum the page cache page index can cope with
         * without overflowing the index or to 2^63 - 1, whichever is smaller.
         */
        sb->s_maxbytes = MAX_LFS_FILESIZE;

        /*
         * Now load the metadata required for the page cache and our address
         * space operations to function. We do this by setting up a specialised
         * read_inode method and then just calling the normal iget() to obtain
         * the inode for $MFT which is sufficient to allow our normal inode
         * operations and associated address space operations to function.
         */
        /*
         * Poison vol->mft_ino so we know whether iget() called into our
         * ntfs_read_inode_mount() method.
         */
#define OGIN    ((struct inode*)le32_to_cpu(0x4e49474f))        /* OGIN */
        vol->mft_ino = OGIN;
        sb->s_op = &ntfs_mount_sops;
        tmp_ino = iget(vol->sb, FILE_MFT);
        if (!tmp_ino || tmp_ino != vol->mft_ino || is_bad_inode(tmp_ino)) {
                if (!silent)
                        ntfs_error(sb, "Failed to load essential metadata.");
                if (tmp_ino && vol->mft_ino == OGIN)
                        ntfs_error(sb, "BUG: iget() did not call "
                                        "ntfs_read_inode_mount() method!\n");
                if (!tmp_ino)
                        goto cond_iput_mft_ino_err_out_now;
                goto iput_tmp_ino_err_out_now;
        }
        /*
         * Note: sb->s_op has already been set to &ntfs_sops by our specialized
         * ntfs_read_inode_mount() method when it was invoked by iget().
         */
        down(&ntfs_lock);
        /*
         * The current mount is a compression user if the cluster size is
         * less than or equal 4kiB.
         */
        if (vol->cluster_size <= 4096 && !ntfs_nr_compression_users++) {
                result = allocate_compression_buffers();
                if (result) {
                        ntfs_error(NULL, "Failed to allocate buffers "
                                        "for compression engine.");
                        ntfs_nr_compression_users--;
                        up(&ntfs_lock);
                        goto iput_tmp_ino_err_out_now;
                }
        }
        /*
         * Increment the number of mounts and generate the global default
         * upcase table if necessary. Also temporarily increment the number of
         * upcase users to avoid race conditions with concurrent (u)mounts.
         */
        if (!ntfs_nr_mounts++)
                default_upcase = generate_default_upcase();
        ntfs_nr_upcase_users++;

        up(&ntfs_lock);
        /*
         * From now on, ignore @silent parameter. If we fail below this line,
         * it will be due to a corrupt fs or a system error, so we report it.
         */
        /*
         * Open the system files with normal access functions and complete
         * setting up the ntfs super block.
         */
        if (!load_system_files(vol)) {
                ntfs_error(sb, "Failed to load system files.");
                goto unl_upcase_iput_tmp_ino_err_out_now;
        }
        if ((sb->s_root = d_alloc_root(vol->root_ino))) {
                /* We increment i_count simulating an ntfs_iget(). */
                atomic_inc(&vol->root_ino->i_count);
                ntfs_debug("Exiting, status successful.");
                /* Release the default upcase if it has no users. */
                down(&ntfs_lock);
                if (!--ntfs_nr_upcase_users && default_upcase) {
                        ntfs_free(default_upcase);
                        default_upcase = NULL;
                }
                up(&ntfs_lock);
                return 0;
        }
        ntfs_error(sb, "Failed to allocate root directory.");
        /* Clean up after the successful load_system_files() call from above. */
        iput(vol->vol_ino);
        vol->vol_ino = NULL;
        /* NTFS 3.0+ specific clean up. */
        if (vol->major_ver >= 3) {
                iput(vol->secure_ino);
                vol->secure_ino = NULL;
        }
        iput(vol->root_ino);
        vol->root_ino = NULL;
        iput(vol->lcnbmp_ino);
        vol->lcnbmp_ino = NULL;
        iput(vol->mftmirr_ino);
        vol->mftmirr_ino = NULL;
        iput(vol->mftbmp_ino);
        vol->mftbmp_ino = NULL;
        vol->upcase_len = 0;
        if (vol->upcase != default_upcase)
                ntfs_free(vol->upcase);
        vol->upcase = NULL;
        if (vol->nls_map) {
                unload_nls(vol->nls_map);
                vol->nls_map = NULL;
        }
        /* Error exit code path. */
unl_upcase_iput_tmp_ino_err_out_now:
        /*
         * Decrease the number of mounts and destroy the global default upcase
         * table if necessary.
         */
        down(&ntfs_lock);
        ntfs_nr_mounts--;
        if (!--ntfs_nr_upcase_users && default_upcase) {
                ntfs_free(default_upcase);
                default_upcase = NULL;
        }
        if (vol->cluster_size <= 4096 && !--ntfs_nr_compression_users)
                free_compression_buffers();
        up(&ntfs_lock);
iput_tmp_ino_err_out_now:
        iput(tmp_ino);
cond_iput_mft_ino_err_out_now:
        if (vol->mft_ino && vol->mft_ino != OGIN && vol->mft_ino != tmp_ino) {
                iput(vol->mft_ino);
                vol->mft_ino = NULL;
        }
#undef OGIN
        /*
         * This is needed to get ntfs_clear_extent_inode() called for each
         * inode we have ever called ntfs_iget()/iput() on, otherwise we A)
         * leak resources and B) a subsequent mount fails automatically due to
         * ntfs_iget() never calling down into our ntfs_read_locked_inode()
         * method again... FIXME: Do we need to do this twice now because of
         * attribute inodes? I think not, so leave as is for now... (AIA)
         */
        if (invalidate_inodes(sb)) {
                ntfs_error(sb, "Busy inodes left. This is most likely a NTFS "
                                "driver bug.");
                /* Copied from fs/super.c. I just love this message. (-; */
                printk("NTFS: Busy inodes after umount. Self-destruct in 5 "
                                "seconds.  Have a nice day...\n");
        }
        /* Errors at this stage are irrelevant. */
err_out_now:
        sb->s_fs_info = NULL;
        kfree(vol);
        ntfs_debug("Failed, returning -EINVAL.");
        return -EINVAL;
}

/*
 * This is a slab cache to optimize allocations and deallocations of Unicode
 * strings of the maximum length allowed by NTFS, which is NTFS_MAX_NAME_LEN
 * (255) Unicode characters + a terminating NULL Unicode character.
 */
kmem_cache_t *ntfs_name_cache;

/* Slab caches for efficient allocation/deallocation of of inodes. */
kmem_cache_t *ntfs_inode_cache;
kmem_cache_t *ntfs_big_inode_cache;

/* Init once constructor for the inode slab cache. */
static void ntfs_big_inode_init_once(void *foo, kmem_cache_t *cachep,
                unsigned long flags)
{
        ntfs_inode *ni = (ntfs_inode *)foo;

        if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
                        SLAB_CTOR_CONSTRUCTOR)
                inode_init_once(VFS_I(ni));
}

/*
 * Slab cache to optimize allocations and deallocations of attribute search
 * contexts.
 */
kmem_cache_t *ntfs_attr_ctx_cache;

/* A global default upcase table and a corresponding reference count. */
wchar_t *default_upcase = NULL;
unsigned long ntfs_nr_upcase_users = 0;

/* The number of mounted filesystems. */
unsigned long ntfs_nr_mounts = 0;

/* Driver wide semaphore. */
DECLARE_MUTEX(ntfs_lock);

static struct super_block *ntfs_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *data)
{
        return get_sb_bdev(fs_type, flags, dev_name, data, ntfs_fill_super);
}

static struct file_system_type ntfs_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "ntfs",
        .get_sb         = ntfs_get_sb,
        .kill_sb        = kill_block_super,
        .fs_flags       = FS_REQUIRES_DEV,
};

/* Stable names for the slab caches. */
static const char *ntfs_attr_ctx_cache_name = "ntfs_attr_ctx_cache";
static const char *ntfs_name_cache_name = "ntfs_name_cache";
static const char *ntfs_inode_cache_name = "ntfs_inode_cache";
static const char *ntfs_big_inode_cache_name = "ntfs_big_inode_cache";

static int __init init_ntfs_fs(void)
{
        int err = 0;

        /* This may be ugly but it results in pretty output so who cares. (-8 */
        printk(KERN_INFO "NTFS driver " NTFS_VERSION " [Flags: R/"
#ifdef NTFS_RW
                        "W"
#else
                        "O"
#endif
#ifdef DEBUG
                        " DEBUG"
#endif
#ifdef MODULE
                        " MODULE"
#endif
                        "].\n");

        ntfs_debug("Debug messages are enabled.");

        ntfs_attr_ctx_cache = kmem_cache_create(ntfs_attr_ctx_cache_name,
                        sizeof(attr_search_context), 0 /* offset */,
                        SLAB_HWCACHE_ALIGN, NULL /* ctor */, NULL /* dtor */);
        if (!ntfs_attr_ctx_cache) {
                printk(KERN_CRIT "NTFS: Failed to create %s!\n",
                                ntfs_attr_ctx_cache_name);
                goto ctx_err_out;
        }

        ntfs_name_cache = kmem_cache_create(ntfs_name_cache_name,
                        (NTFS_MAX_NAME_LEN+1) * sizeof(uchar_t), 0,
                        SLAB_HWCACHE_ALIGN, NULL, NULL);
        if (!ntfs_name_cache) {
                printk(KERN_CRIT "NTFS: Failed to create %s!\n",
                                ntfs_name_cache_name);
                goto name_err_out;
        }

        ntfs_inode_cache = kmem_cache_create(ntfs_inode_cache_name,
                        sizeof(ntfs_inode), 0, 
                        SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, NULL, NULL);
        if (!ntfs_inode_cache) {
                printk(KERN_CRIT "NTFS: Failed to create %s!\n",
                                ntfs_inode_cache_name);
                goto inode_err_out;
        }

        ntfs_big_inode_cache = kmem_cache_create(ntfs_big_inode_cache_name,
                        sizeof(big_ntfs_inode), 0, 
                        SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT,
                        ntfs_big_inode_init_once, NULL);
        if (!ntfs_big_inode_cache) {
                printk(KERN_CRIT "NTFS: Failed to create %s!\n",
                                ntfs_big_inode_cache_name);
                goto big_inode_err_out;
        }

        /* Register the ntfs sysctls. */
        err = ntfs_sysctl(1);
        if (err) {
                printk(KERN_CRIT "NTFS: Failed to register NTFS sysctls!\n");
                goto sysctl_err_out;
        }

        err = register_filesystem(&ntfs_fs_type);
        if (!err) {
                ntfs_debug("NTFS driver registered successfully.");
                return 0; /* Success! */
        }
        printk(KERN_CRIT "NTFS: Failed to register NTFS file system driver!\n");

sysctl_err_out:
        kmem_cache_destroy(ntfs_big_inode_cache);
big_inode_err_out:
        kmem_cache_destroy(ntfs_inode_cache);
inode_err_out:
        kmem_cache_destroy(ntfs_name_cache);
name_err_out:
        kmem_cache_destroy(ntfs_attr_ctx_cache);
ctx_err_out:
        if (!err) {
                printk(KERN_CRIT "NTFS: Aborting NTFS file system driver "
                                "registration...\n");
                err = -ENOMEM;
        }
        return err;
}

static void __exit exit_ntfs_fs(void)
{
        int err = 0;

        ntfs_debug("Unregistering NTFS driver.");

        unregister_filesystem(&ntfs_fs_type);

        if (kmem_cache_destroy(ntfs_big_inode_cache) && (err = 1))
                printk(KERN_CRIT "NTFS: Failed to destory %s.\n",
                                ntfs_big_inode_cache_name);
        if (kmem_cache_destroy(ntfs_inode_cache) && (err = 1))
                printk(KERN_CRIT "NTFS: Failed to destory %s.\n",
                                ntfs_inode_cache_name);
        if (kmem_cache_destroy(ntfs_name_cache) && (err = 1))
                printk(KERN_CRIT "NTFS: Failed to destory %s.\n",
                                ntfs_name_cache_name);
        if (kmem_cache_destroy(ntfs_attr_ctx_cache) && (err = 1))
                printk(KERN_CRIT "NTFS: Failed to destory %s.\n",
                                ntfs_attr_ctx_cache_name);
        if (err)
                printk(KERN_CRIT "NTFS: This causes memory to leak! There is "
                                "probably a BUG in the driver! Please report "
                                "you saw this message to "
                                "linux-ntfs-dev@lists.sf.net\n");
        /* Unregister the ntfs sysctls. */
        ntfs_sysctl(0);
}

MODULE_AUTHOR("Anton Altaparmakov <aia21@cantab.net>");
MODULE_DESCRIPTION("NTFS 1.2/3.x driver - Copyright (c) 2001-2003 Anton Altaparmakov");
MODULE_LICENSE("GPL");
#ifdef DEBUG
MODULE_PARM(debug_msgs, "i");
MODULE_PARM_DESC(debug_msgs, "Enable debug messages.");
#endif

module_init(init_ntfs_fs)
module_exit(exit_ntfs_fs)