lib/libstand/nandfs.c

/*-
 * Copyright (c) 2010-2012 Semihalf.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/queue.h>
#include <sys/stdint.h>
#include <ufs/ufs/dinode.h>
#include <fs/nandfs/nandfs_fs.h>
#include "stand.h"
#include "string.h"
#include "zlib.h"

#define DEBUG
#undef DEBUG
#ifdef DEBUG
#define NANDFS_DEBUG(fmt, args...) do { \
    printf("NANDFS_DEBUG:" fmt "\n", ##args); } while (0)
#else
#define NANDFS_DEBUG(fmt, args...)
#endif

struct nandfs_mdt {
    uint32_t    entries_per_block;
    uint32_t    entries_per_group;
    uint32_t    blocks_per_group;
    uint32_t    groups_per_desc_block;  /* desc is super group */
    uint32_t    blocks_per_desc_block;  /* desc is super group */
};

struct bmap_buf {
    LIST_ENTRY(bmap_buf)    list;
    nandfs_daddr_t      blknr;
    uint64_t        *map;
};

struct nandfs_node {
    struct nandfs_inode *inode;
    LIST_HEAD(, bmap_buf)   bmap_bufs;
};
struct nandfs {
    int nf_blocksize;
    int nf_sectorsize;
    int nf_cpno;

    struct open_file    *nf_file;
    struct nandfs_node  *nf_opened_node;
    u_int           nf_offset;
    uint8_t         *nf_buf;
    int64_t         nf_buf_blknr;

    struct nandfs_fsdata        *nf_fsdata;
    struct nandfs_super_block   *nf_sb;
    struct nandfs_segment_summary   nf_segsum;
    struct nandfs_checkpoint    nf_checkpoint;
    struct nandfs_super_root    nf_sroot;
    struct nandfs_node      nf_ifile;
    struct nandfs_node      nf_datfile;
    struct nandfs_node      nf_cpfile;
    struct nandfs_mdt       nf_datfile_mdt;
    struct nandfs_mdt       nf_ifile_mdt;

    int nf_nindir[NIADDR];
};

static int nandfs_open(const char *, struct open_file *);
static int nandfs_close(struct open_file *);
static int nandfs_read(struct open_file *, void *, size_t, size_t *);
static off_t nandfs_seek(struct open_file *, off_t, int);
static int nandfs_stat(struct open_file *, struct stat *);
static int nandfs_readdir(struct open_file *, struct dirent *);

static int nandfs_buf_read(struct nandfs *, void **, size_t *);
static struct nandfs_node *nandfs_lookup_path(struct nandfs *, const char *);
static int nandfs_read_inode(struct nandfs *, struct nandfs_node *,
    nandfs_lbn_t, u_int, void *, int);
static int nandfs_read_blk(struct nandfs *, nandfs_daddr_t, void *, int);
static int nandfs_bmap_lookup(struct nandfs *, struct nandfs_node *,
    nandfs_lbn_t, nandfs_daddr_t *, int);
static int nandfs_get_checkpoint(struct nandfs *, uint64_t,
    struct nandfs_checkpoint *);
static nandfs_daddr_t nandfs_vtop(struct nandfs *, nandfs_daddr_t);
static void nandfs_calc_mdt_consts(int, struct nandfs_mdt *, int);
static void nandfs_mdt_trans(struct nandfs_mdt *, uint64_t,
    nandfs_daddr_t *, uint32_t *);
static int ioread(struct open_file *, off_t, void *, u_int);
static int nandfs_probe_sectorsize(struct open_file *);

struct fs_ops nandfs_fsops = {
    "nandfs",
    nandfs_open,
    nandfs_close,
    nandfs_read,
    null_write,
    nandfs_seek,
    nandfs_stat,
    nandfs_readdir
};

#define NINDIR(fs)  ((fs)->nf_blocksize / sizeof(nandfs_daddr_t))

/* from NetBSD's src/sys/net/if_ethersubr.c */
static uint32_t
nandfs_crc32(uint32_t crc, const uint8_t *buf, size_t len)
{
    static const uint32_t crctab[] = {
        0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
        0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
        0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
        0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
    };
    size_t i;

    crc = crc ^ ~0U;
    for (i = 0; i < len; i++) {
        crc ^= buf[i];
        crc = (crc >> 4) ^ crctab[crc & 0xf];
        crc = (crc >> 4) ^ crctab[crc & 0xf];
    }
    return (crc ^ ~0U);
}

static int
nandfs_check_fsdata_crc(struct nandfs_fsdata *fsdata)
{
    uint32_t fsdata_crc, comp_crc;

    if (fsdata->f_magic != NANDFS_FSDATA_MAGIC)
        return (0);

    /* Preserve crc */
    fsdata_crc = fsdata->f_sum;

    /* Calculate */
    fsdata->f_sum = (0);
    comp_crc = nandfs_crc32(0, (uint8_t *)fsdata, fsdata->f_bytes);

    /* Restore */
    fsdata->f_sum = fsdata_crc;

    /* Check CRC */
    return (fsdata_crc == comp_crc);
}

static int
nandfs_check_superblock_crc(struct nandfs_fsdata *fsdata,
    struct nandfs_super_block *super)
{
    uint32_t super_crc, comp_crc;

    /* Check super block magic */
    if (super->s_magic != NANDFS_SUPER_MAGIC)
        return (0);

    /* Preserve CRC */
    super_crc = super->s_sum;

    /* Calculate */
    super->s_sum = (0);
    comp_crc = nandfs_crc32(0, (uint8_t *)super, fsdata->f_sbbytes);

    /* Restore */
    super->s_sum = super_crc;

    /* Check CRC */
    return (super_crc == comp_crc);
}

static int
nandfs_find_super_block(struct nandfs *fs, struct open_file *f)
{
    struct nandfs_super_block *sb;
    int i, j, n, s;
    int sectors_to_read, error;

    sb = malloc(fs->nf_sectorsize);
    if (sb == NULL)
        return (ENOMEM);

    memset(fs->nf_sb, 0, sizeof(*fs->nf_sb));

    sectors_to_read = (NANDFS_NFSAREAS * fs->nf_fsdata->f_erasesize) /
        fs->nf_sectorsize;
    for (i = 0; i < sectors_to_read; i++) {
        NANDFS_DEBUG("reading i %d offset %d\n", i,
            i * fs->nf_sectorsize);
        error = ioread(f, i * fs->nf_sectorsize, (char *)sb,
            fs->nf_sectorsize);
        if (error) {
            NANDFS_DEBUG("error %d\n", error);
            continue;
        }
        n = fs->nf_sectorsize / sizeof(struct nandfs_super_block);
        s = 0;
        if ((i * fs->nf_sectorsize) % fs->nf_fsdata->f_erasesize == 0) {
            if (fs->nf_sectorsize == sizeof(struct nandfs_fsdata))
                continue;
            else {
                s += (sizeof(struct nandfs_fsdata) /
                    sizeof(struct nandfs_super_block));
            }
        }

        for (j = s; j < n; j++) {
            if (!nandfs_check_superblock_crc(fs->nf_fsdata, &sb[j]))
                continue;
            NANDFS_DEBUG("magic %x wtime %jd, lastcp 0x%jx\n",
                sb[j].s_magic, sb[j].s_wtime, sb[j].s_last_cno);
            if (sb[j].s_last_cno > fs->nf_sb->s_last_cno)
                memcpy(fs->nf_sb, &sb[j], sizeof(*fs->nf_sb));
        }
    }

    free(sb);

    return (fs->nf_sb->s_magic != 0 ? 0 : EINVAL);
}

static int
nandfs_find_fsdata(struct nandfs *fs, struct open_file *f)
{
    int offset, error, i;

    NANDFS_DEBUG("starting\n");

    offset = 0;
    for (i = 0; i < 64 * NANDFS_NFSAREAS; i++) {
        error = ioread(f, offset, (char *)fs->nf_fsdata,
            sizeof(struct nandfs_fsdata));
        if (error)
            return (error);
        if (fs->nf_fsdata->f_magic == NANDFS_FSDATA_MAGIC) {
            NANDFS_DEBUG("found at %x, volume %s\n", offset,
                fs->nf_fsdata->f_volume_name);
            if (nandfs_check_fsdata_crc(fs->nf_fsdata))
                break;
        }
        offset += fs->nf_sectorsize;
    }

    return (error);
}

static int
nandfs_read_structures(struct nandfs *fs, struct open_file *f)
{
    int error;

    error = nandfs_find_fsdata(fs, f);
    if (error)
        return (error);

    error = nandfs_find_super_block(fs, f);

    if (error == 0)
        NANDFS_DEBUG("selected sb with w_time %jd last_pseg %jx\n",
            fs->nf_sb->s_wtime, fs->nf_sb->s_last_pseg);

    return (error);
}

static int
nandfs_mount(struct nandfs *fs, struct open_file *f)
{
    int err = 0, level;
    uint64_t last_pseg;

    fs->nf_fsdata = malloc(sizeof(struct nandfs_fsdata));
    fs->nf_sb = malloc(sizeof(struct nandfs_super_block));

    err = nandfs_read_structures(fs, f);
    if (err) {
        free(fs->nf_fsdata);
        free(fs->nf_sb);
        return (err);
    }

    fs->nf_blocksize = 1 << (fs->nf_fsdata->f_log_block_size + 10);

    NANDFS_DEBUG("using superblock with wtime %jd\n", fs->nf_sb->s_wtime);

    fs->nf_cpno = fs->nf_sb->s_last_cno;
    last_pseg = fs->nf_sb->s_last_pseg;

    /*
     * Calculate indirect block levels.
     */
    nandfs_daddr_t mult;

    mult = 1;
    for (level = 0; level < NIADDR; level++) {
        mult *= NINDIR(fs);
        fs->nf_nindir[level] = mult;
    }

    nandfs_calc_mdt_consts(fs->nf_blocksize, &fs->nf_datfile_mdt,
        fs->nf_fsdata->f_dat_entry_size);

    nandfs_calc_mdt_consts(fs->nf_blocksize, &fs->nf_ifile_mdt,
        fs->nf_fsdata->f_inode_size);

    err = ioread(f, last_pseg * fs->nf_blocksize, &fs->nf_segsum,
        sizeof(struct nandfs_segment_summary));
    if (err) {
        free(fs->nf_sb);
        free(fs->nf_fsdata);
        return (err);
    }

    err = ioread(f, (last_pseg + fs->nf_segsum.ss_nblocks - 1) *
        fs->nf_blocksize, &fs->nf_sroot, sizeof(struct nandfs_super_root));
    if (err) {
        free(fs->nf_sb);
        free(fs->nf_fsdata);
        return (err);
    }

    fs->nf_datfile.inode = &fs->nf_sroot.sr_dat;
    LIST_INIT(&fs->nf_datfile.bmap_bufs);
    fs->nf_cpfile.inode = &fs->nf_sroot.sr_cpfile;
    LIST_INIT(&fs->nf_cpfile.bmap_bufs);

    err = nandfs_get_checkpoint(fs, fs->nf_cpno, &fs->nf_checkpoint);
    if (err) {
        free(fs->nf_sb);
        free(fs->nf_fsdata);
        return (err);
    }

    NANDFS_DEBUG("checkpoint cp_cno=%lld\n", fs->nf_checkpoint.cp_cno);
    NANDFS_DEBUG("checkpoint cp_inodes_count=%lld\n",
        fs->nf_checkpoint.cp_inodes_count);
    NANDFS_DEBUG("checkpoint cp_ifile_inode.i_blocks=%lld\n",
        fs->nf_checkpoint.cp_ifile_inode.i_blocks);

    fs->nf_ifile.inode = &fs->nf_checkpoint.cp_ifile_inode;
    LIST_INIT(&fs->nf_ifile.bmap_bufs);
    return (0);
}

#define NINDIR(fs)  ((fs)->nf_blocksize / sizeof(nandfs_daddr_t))

static int
nandfs_open(const char *path, struct open_file *f)
{
    struct nandfs *fs;
    struct nandfs_node *node;
    int err, bsize, level;

    NANDFS_DEBUG("nandfs_open('%s', %p)\n", path, f);

    fs = malloc(sizeof(struct nandfs));
    f->f_fsdata = fs;
    fs->nf_file = f;

    bsize = nandfs_probe_sectorsize(f);
    if (bsize < 0) {
        printf("Cannot probe medium sector size\n");
        return (EINVAL);
    }

    fs->nf_sectorsize = bsize;

    /*
     * Calculate indirect block levels.
     */
    nandfs_daddr_t mult;

    mult = 1;
    for (level = 0; level < NIADDR; level++) {
        mult *= NINDIR(fs);
        fs->nf_nindir[level] = mult;
    }

    NANDFS_DEBUG("fs %p nf_sectorsize=%x\n", fs, fs->nf_sectorsize);

    err = nandfs_mount(fs, f);
    if (err) {
        NANDFS_DEBUG("Cannot mount nandfs: %s\n", strerror(err));
        return (err);
    }

    node = nandfs_lookup_path(fs, path);
    if (node == NULL)
        return (EINVAL);

    fs->nf_offset = 0;
    fs->nf_buf = NULL;
    fs->nf_buf_blknr = -1;
    fs->nf_opened_node = node;
    LIST_INIT(&fs->nf_opened_node->bmap_bufs);
    return (0);
}

static void
nandfs_free_node(struct nandfs_node *node)
{
    struct bmap_buf *bmap, *tmp;

    free(node->inode);
    LIST_FOREACH_SAFE(bmap, &node->bmap_bufs, list, tmp) {
        LIST_REMOVE(bmap, list);
        free(bmap->map);
        free(bmap);
    }
    free(node);
}

static int
nandfs_close(struct open_file *f)
{
    struct nandfs *fs = f->f_fsdata;

    NANDFS_DEBUG("nandfs_close(%p)\n", f);

    if (fs->nf_buf != NULL)
        free(fs->nf_buf);

    nandfs_free_node(fs->nf_opened_node);
    free(fs->nf_sb);
    free(fs);
    return (0);
}

static int
nandfs_read(struct open_file *f, void *addr, size_t size, size_t *resid)
{
    struct nandfs *fs = (struct nandfs *)f->f_fsdata;
    size_t csize, buf_size;
    void *buf;
    int error = 0;

    NANDFS_DEBUG("nandfs_read(file=%p, addr=%p, size=%d)\n", f, addr, size);

    while (size != 0) {
        if (fs->nf_offset >= fs->nf_opened_node->inode->i_size)
            break;

        error = nandfs_buf_read(fs, &buf, &buf_size);
        if (error)
            break;

        csize = size;
        if (csize > buf_size)
            csize = buf_size;

        bcopy(buf, addr, csize);

        fs->nf_offset += csize;
        addr = (char *)addr + csize;
        size -= csize;
    }

    if (resid)
        *resid = size;
    return (error);
}

static off_t
nandfs_seek(struct open_file *f, off_t offset, int where)
{
    struct nandfs *fs = f->f_fsdata;
    off_t off;
    u_int size;

    NANDFS_DEBUG("nandfs_seek(file=%p, offset=%lld, where=%d)\n", f,
        offset, where);

    size = fs->nf_opened_node->inode->i_size;

    switch (where) {
    case SEEK_SET:
        off = 0;
        break;
    case SEEK_CUR:
        off = fs->nf_offset;
        break;
    case SEEK_END:
        off = size;
        break;
    default:
        errno = EINVAL;
        return (-1);
    }

    off += offset;
    if (off < 0 || off > size) {
        errno = EINVAL;
        return(-1);
    }

    fs->nf_offset = (u_int)off;

    return (off);
}

static int
nandfs_stat(struct open_file *f, struct stat *sb)
{
    struct nandfs *fs = f->f_fsdata;

    NANDFS_DEBUG("nandfs_stat(file=%p, stat=%p)\n", f, sb);

    sb->st_size = fs->nf_opened_node->inode->i_size;
    sb->st_mode = fs->nf_opened_node->inode->i_mode;
    sb->st_uid = fs->nf_opened_node->inode->i_uid;
    sb->st_gid = fs->nf_opened_node->inode->i_gid;
    return (0);
}

static int
nandfs_readdir(struct open_file *f, struct dirent *d)
{
    struct nandfs *fs = f->f_fsdata;
    struct nandfs_dir_entry *dirent;
    void *buf;
    size_t buf_size;

    NANDFS_DEBUG("nandfs_readdir(file=%p, dirent=%p)\n", f, d);

    if (fs->nf_offset >= fs->nf_opened_node->inode->i_size) {
        NANDFS_DEBUG("nandfs_readdir(file=%p, dirent=%p) ENOENT\n",
            f, d);
        return (ENOENT);
    }

    if (nandfs_buf_read(fs, &buf, &buf_size)) {
        NANDFS_DEBUG("nandfs_readdir(file=%p, dirent=%p)"
            "buf_read failed\n", f, d);
        return (EIO);
    }

    NANDFS_DEBUG("nandfs_readdir(file=%p, dirent=%p) moving forward\n",
        f, d);

    dirent = (struct nandfs_dir_entry *)buf;
    fs->nf_offset += dirent->rec_len;
    strncpy(d->d_name, dirent->name, dirent->name_len);
    d->d_name[dirent->name_len] = '\0';
    d->d_type = dirent->file_type;
    return (0);
}

static int
nandfs_buf_read(struct nandfs *fs, void **buf_p, size_t *size_p)
{
    nandfs_daddr_t blknr, blkoff;

    blknr = fs->nf_offset / fs->nf_blocksize;
    blkoff = fs->nf_offset % fs->nf_blocksize;

    if (blknr != fs->nf_buf_blknr) {
        if (fs->nf_buf == NULL)
            fs->nf_buf = malloc(fs->nf_blocksize);

        if (nandfs_read_inode(fs, fs->nf_opened_node, blknr, 1,
            fs->nf_buf, 0))
            return (EIO);

        fs->nf_buf_blknr = blknr;
    }

    *buf_p = fs->nf_buf + blkoff;
    *size_p = fs->nf_blocksize - blkoff;

    NANDFS_DEBUG("nandfs_buf_read buf_p=%p size_p=%d\n", *buf_p, *size_p);

    if (*size_p > fs->nf_opened_node->inode->i_size - fs->nf_offset)
        *size_p = fs->nf_opened_node->inode->i_size - fs->nf_offset;

    return (0);
}

static struct nandfs_node *
nandfs_lookup_node(struct nandfs *fs, uint64_t ino)
{
    uint64_t blocknr;
    int entrynr;
    struct nandfs_inode *buffer;
    struct nandfs_node *node;
    struct nandfs_inode *inode;

    NANDFS_DEBUG("nandfs_lookup_node ino=%lld\n", ino);

    if (ino == 0) {
        printf("nandfs_lookup_node: invalid inode requested\n");
        return (NULL);
    }

    buffer = malloc(fs->nf_blocksize);
    inode = malloc(sizeof(struct nandfs_inode));
    node = malloc(sizeof(struct nandfs_node));

    nandfs_mdt_trans(&fs->nf_ifile_mdt, ino, &blocknr, &entrynr);

    if (nandfs_read_inode(fs, &fs->nf_ifile, blocknr, 1, buffer, 0))
        return (NULL);

    memcpy(inode, &buffer[entrynr], sizeof(struct nandfs_inode));
    node->inode = inode;
    free(buffer);
    return (node);
}

static struct nandfs_node *
nandfs_lookup_path(struct nandfs *fs, const char *path)
{
    struct nandfs_node *node;
    struct nandfs_dir_entry *dirent;
    char *namebuf;
    uint64_t i, done, pinode, inode;
    int nlinks = 0, counter, len, link_len, nameidx;
    uint8_t *buffer, *orig;
    char *strp, *lpath;

    buffer = malloc(fs->nf_blocksize);
    orig = buffer;

    namebuf = malloc(2 * MAXPATHLEN + 2);
    strncpy(namebuf, path, MAXPATHLEN);
    namebuf[MAXPATHLEN] = '\0';
    done = nameidx = 0;
    lpath = namebuf;

    /* Get the root inode */
    node = nandfs_lookup_node(fs, NANDFS_ROOT_INO);
    inode = NANDFS_ROOT_INO;

    while ((strp = strsep(&lpath, "/")) != NULL) {
        if (*strp == '\0')
            continue;
        if ((node->inode->i_mode & IFMT) != IFDIR) {
            nandfs_free_node(node);
            node = NULL;
            goto out;
        }

        len = strlen(strp);
        NANDFS_DEBUG("%s: looking for %s\n", __func__, strp);
        for (i = 0; i < node->inode->i_blocks; i++) {
            if (nandfs_read_inode(fs, node, i, 1, orig, 0)) {
                node = NULL;
                goto out;
            }

            buffer = orig;
            done = counter = 0;
            while (1) {
                dirent =
                    (struct nandfs_dir_entry *)(void *)buffer;
                NANDFS_DEBUG("%s: dirent.name = %s\n",
                    __func__, dirent->name);
                NANDFS_DEBUG("%s: dirent.rec_len = %d\n",
                    __func__, dirent->rec_len);
                NANDFS_DEBUG("%s: dirent.inode = %lld\n",
                    __func__, dirent->inode);
                if (len == dirent->name_len &&
                    (strncmp(strp, dirent->name, len) == 0) &&
                    dirent->inode != 0) {
                    nandfs_free_node(node);
                    node = nandfs_lookup_node(fs,
                        dirent->inode);
                    pinode = inode;
                    inode = dirent->inode;
                    done = 1;
                    break;
                }

                counter += dirent->rec_len;
                buffer += dirent->rec_len;

                if (counter == fs->nf_blocksize)
                    break;
            }

            if (done)
                break;
        }

        if (!done) {
            node = NULL;
            goto out;
        }

        NANDFS_DEBUG("%s: %.*s has mode %o\n", __func__,
            dirent->name_len, dirent->name, node->inode->i_mode);

        if ((node->inode->i_mode & IFMT) == IFLNK) {
            NANDFS_DEBUG("%s: %.*s is symlink\n",
                __func__, dirent->name_len, dirent->name);
            link_len = node->inode->i_size;

            if (++nlinks > MAXSYMLINKS) {
                nandfs_free_node(node);
                node = NULL;
                goto out;
            }

            if (nandfs_read_inode(fs, node, 0, 1, orig, 0)) {
                nandfs_free_node(node);
                node = NULL;
                goto out;
            }

            NANDFS_DEBUG("%s: symlink is  %.*s\n",
                __func__, link_len, (char *)orig);

            nameidx = (nameidx == 0) ? MAXPATHLEN + 1 : 0;
            bcopy((char *)orig, namebuf + nameidx,
                (unsigned)link_len);
            if (lpath != NULL) {
                namebuf[nameidx + link_len++] = '/';
                strncpy(namebuf + nameidx + link_len, lpath,
                    MAXPATHLEN - link_len);
                namebuf[nameidx + MAXPATHLEN] = '\0';
            } else
                namebuf[nameidx + link_len] = '\0';

            NANDFS_DEBUG("%s: strp=%s, lpath=%s, namebuf0=%s, "
                "namebuf1=%s, idx=%d\n", __func__, strp, lpath,
                namebuf + 0, namebuf + MAXPATHLEN + 1, nameidx);

            lpath = namebuf + nameidx;

            nandfs_free_node(node);

            /*
             * If absolute pathname, restart at root. Otherwise
             * continue with out parent inode.
             */
            inode = (orig[0] == '/') ? NANDFS_ROOT_INO : pinode;
            node = nandfs_lookup_node(fs, inode);
        }
    }

out:
    free(namebuf);
    free(orig);
    return (node);
}

static int
nandfs_read_inode(struct nandfs *fs, struct nandfs_node *node,
    nandfs_daddr_t blknr, u_int nblks, void *buf, int raw)
{
    uint64_t *pblks;
    uint64_t *vblks;
    u_int i;
    int error;

    pblks = malloc(nblks * sizeof(uint64_t));
    vblks = malloc(nblks * sizeof(uint64_t));

    NANDFS_DEBUG("nandfs_read_inode fs=%p node=%p blknr=%lld nblks=%d\n",
        fs, node, blknr, nblks);
    for (i = 0; i < nblks; i++) {
        error = nandfs_bmap_lookup(fs, node, blknr + i, &vblks[i], raw);
        if (error) {
            free(pblks);
            free(vblks);
            return (error);
        }
        if (raw == 0)
            pblks[i] = nandfs_vtop(fs, vblks[i]);
        else
            pblks[i] = vblks[i];
    }

    for (i = 0; i < nblks; i++) {
        if (ioread(fs->nf_file, pblks[i] * fs->nf_blocksize, buf,
            fs->nf_blocksize)) {
            free(pblks);
            free(vblks);
            return (EIO);
        }

        buf = (void *)((uintptr_t)buf + fs->nf_blocksize);
    }

    free(pblks);
    free(vblks);
    return (0);
}

static int
nandfs_read_blk(struct nandfs *fs, nandfs_daddr_t blknr, void *buf, int phys)
{
    uint64_t pblknr;

    pblknr = (phys ? blknr : nandfs_vtop(fs, blknr));

    return (ioread(fs->nf_file, pblknr * fs->nf_blocksize, buf,
        fs->nf_blocksize));
}

static int
nandfs_get_checkpoint(struct nandfs *fs, uint64_t cpno,
    struct nandfs_checkpoint *cp)
{
    uint64_t blocknr;
    int blockoff, cp_per_block, dlen;
    uint8_t *buf;

    NANDFS_DEBUG("nandfs_get_checkpoint(fs=%p cpno=%lld)\n", fs, cpno);

    buf = malloc(fs->nf_blocksize);

    cpno += NANDFS_CPFILE_FIRST_CHECKPOINT_OFFSET - 1;
    dlen = fs->nf_fsdata->f_checkpoint_size;
    cp_per_block = fs->nf_blocksize / dlen;
    blocknr = cpno / cp_per_block;
    blockoff = (cpno % cp_per_block) * dlen;

    if (nandfs_read_inode(fs, &fs->nf_cpfile, blocknr, 1, buf, 0)) {
        free(buf);
        return (EINVAL);
    }

    memcpy(cp, buf + blockoff, sizeof(struct nandfs_checkpoint));
    free(buf);

    return (0);
}

static uint64_t *
nandfs_get_map(struct nandfs *fs, struct nandfs_node *node, nandfs_daddr_t blknr,
    int phys)
{
    struct bmap_buf *bmap;
    uint64_t *map;

    LIST_FOREACH(bmap, &node->bmap_bufs, list) {
        if (bmap->blknr == blknr)
            return (bmap->map);
    }

    map = malloc(fs->nf_blocksize);
    if (nandfs_read_blk(fs, blknr, map, phys)) {
        free(map);
        return (NULL);
    }

    bmap = malloc(sizeof(struct bmap_buf));
    bmap->blknr = blknr;
    bmap->map = map;

    LIST_INSERT_HEAD(&node->bmap_bufs, bmap, list);

    NANDFS_DEBUG("%s:(node=%p, map=%p)\n", __func__, node, map);
    return (map);
}

static int
nandfs_bmap_lookup(struct nandfs *fs, struct nandfs_node *node,
    nandfs_lbn_t lblknr, nandfs_daddr_t *vblknr, int phys)
{
    struct nandfs_inode *ino;
    nandfs_daddr_t ind_block_num;
    uint64_t *map;
    int idx;
    int level;

    ino = node->inode;

    if (lblknr < NDADDR) {
        *vblknr = ino->i_db[lblknr];
        return (0);
    }

    lblknr -= NDADDR;

    /*
     * nindir[0] = NINDIR
     * nindir[1] = NINDIR**2
     * nindir[2] = NINDIR**3
     *  etc
     */
    for (level = 0; level < NIADDR; level++) {
        NANDFS_DEBUG("lblknr=%jx fs->nf_nindir[%d]=%d\n", lblknr, level, fs->nf_nindir[level]);
        if (lblknr < fs->nf_nindir[level])
            break;
        lblknr -= fs->nf_nindir[level];
    }

    if (level == NIADDR) {
        /* Block number too high */
        NANDFS_DEBUG("lblknr %jx too high\n", lblknr);
        return (EFBIG);
    }

    ind_block_num = ino->i_ib[level];

    for (; level >= 0; level--) {
        if (ind_block_num == 0) {
            *vblknr = 0;    /* missing */
            return (0);
        }

        twiddle(1);
        NANDFS_DEBUG("calling get_map with %jx\n", ind_block_num);
        map = nandfs_get_map(fs, node, ind_block_num, phys);
        if (map == NULL)
            return (EIO);

        if (level > 0) {
            idx = lblknr / fs->nf_nindir[level - 1];
            lblknr %= fs->nf_nindir[level - 1];
        } else
            idx = lblknr;

        ind_block_num = ((nandfs_daddr_t *)map)[idx];
    }

    *vblknr = ind_block_num;

    return (0);
}

static nandfs_daddr_t
nandfs_vtop(struct nandfs *fs, nandfs_daddr_t vblocknr)
{
    nandfs_lbn_t blocknr;
    nandfs_daddr_t pblocknr;
    int entrynr;
    struct nandfs_dat_entry *dat;

    dat = malloc(fs->nf_blocksize);
    nandfs_mdt_trans(&fs->nf_datfile_mdt, vblocknr, &blocknr, &entrynr);

    if (nandfs_read_inode(fs, &fs->nf_datfile, blocknr, 1, dat, 1)) {
        free(dat);
        return (0);
    }

    NANDFS_DEBUG("nandfs_vtop entrynr=%d vblocknr=%lld pblocknr=%lld\n",
        entrynr, vblocknr, dat[entrynr].de_blocknr);

    pblocknr = dat[entrynr].de_blocknr;
    free(dat);
    return (pblocknr);
}

static void
nandfs_calc_mdt_consts(int blocksize, struct nandfs_mdt *mdt, int entry_size)
{

    mdt->entries_per_group = blocksize * 8;    /* bits in sector */
    mdt->entries_per_block = blocksize / entry_size;
    mdt->blocks_per_group  =
        (mdt->entries_per_group -1) / mdt->entries_per_block + 1 + 1;
    mdt->groups_per_desc_block =
        blocksize / sizeof(struct nandfs_block_group_desc);
    mdt->blocks_per_desc_block =
        mdt->groups_per_desc_block * mdt->blocks_per_group + 1;
}

static void
nandfs_mdt_trans(struct nandfs_mdt *mdt, uint64_t index,
    nandfs_daddr_t *blocknr, uint32_t *entry_in_block)
{
    nandfs_daddr_t blknr;
    uint64_t group, group_offset, blocknr_in_group;
    uint64_t desc_block, desc_offset;

    /* Calculate our offset in the file */
    group = index / mdt->entries_per_group;
    group_offset = index % mdt->entries_per_group;
    desc_block = group / mdt->groups_per_desc_block;
    desc_offset = group % mdt->groups_per_desc_block;
    blocknr_in_group = group_offset / mdt->entries_per_block;

    /* To descgroup offset */
    blknr = 1 + desc_block * mdt->blocks_per_desc_block;

    /* To group offset */
    blknr += desc_offset * mdt->blocks_per_group;

    /* To actual file block */
    blknr += 1 + blocknr_in_group;

    *blocknr        = blknr;
    *entry_in_block = group_offset % mdt->entries_per_block;
}

static int
ioread(struct open_file *f, off_t pos, void *buf, u_int length)
{
    void *buffer;
    int err;
    int bsize = ((struct nandfs *)f->f_fsdata)->nf_sectorsize;
    u_int off, nsec;

    off = pos % bsize;
    pos /= bsize;
    nsec = (length + (bsize - 1)) / bsize;

    NANDFS_DEBUG("pos=%lld length=%d off=%d nsec=%d\n", pos, length,
        off, nsec);

    buffer = malloc(nsec * bsize);

    err = (f->f_dev->dv_strategy)(f->f_devdata, F_READ, pos,
        nsec * bsize, buffer, NULL);

    memcpy(buf, (void *)((uintptr_t)buffer + off), length);
    free(buffer);

    return (err);
}

static int
nandfs_probe_sectorsize(struct open_file *f)
{
    void *buffer;
    int i, err;

    buffer = malloc(16 * 1024);

    NANDFS_DEBUG("probing for sector size: ");

    for (i = 512; i < (16 * 1024); i <<= 1) {
        NANDFS_DEBUG("%d ", i);
        err = (f->f_dev->dv_strategy)(f->f_devdata, F_READ, 0, i,
            buffer, NULL);

        if (err == 0) {
            NANDFS_DEBUG("found");
            free(buffer);
            return (i);
        }
    }

    free(buffer);
    NANDFS_DEBUG("not found\n");
    return (-1);
}