/*      $NetBSD: ext2fs_vfsops.c,v 1.229 2025/02/16 16:34:01 joe Exp $  */

/*
 * Copyright (c) 1989, 1991, 1993, 1994
 *      The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *      @(#)ffs_vfsops.c        8.14 (Berkeley) 11/28/94
 * Modified for ext2fs by Manuel Bouyer.
 */

/*
 * Copyright (c) 1997 Manuel Bouyer.
 *
 * 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 ``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 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.
 *
 *      @(#)ffs_vfsops.c        8.14 (Berkeley) 11/28/94
 * Modified for ext2fs by Manuel Bouyer.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ext2fs_vfsops.c,v 1.229 2025/02/16 16:34:01 joe Exp $");

#if defined(_KERNEL_OPT)
#include "opt_compat_netbsd.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/socket.h>
#include <sys/mount.h>
#include <sys/buf.h>
#include <sys/device.h>
#include <sys/file.h>
#include <sys/disklabel.h>
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/pool.h>
#include <sys/lock.h>
#include <sys/conf.h>
#include <sys/kauth.h>
#include <sys/module.h>

#include <miscfs/genfs/genfs.h>
#include <miscfs/specfs/specdev.h>

#include <ufs/ufs/quota.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/dir.h>
#include <ufs/ufs/ufs_extern.h>

#include <ufs/ext2fs/ext2fs.h>
#include <ufs/ext2fs/ext2fs_dir.h>
#include <ufs/ext2fs/ext2fs_extern.h>

MODULE(MODULE_CLASS_VFS, ext2fs, "ufs");

int ext2fs_sbupdate(struct ufsmount *, int);
static int ext2fs_sbfill(struct m_ext2fs *, int);

extern const struct vnodeopv_desc ext2fs_vnodeop_opv_desc;
extern const struct vnodeopv_desc ext2fs_specop_opv_desc;
extern const struct vnodeopv_desc ext2fs_fifoop_opv_desc;

const struct vnodeopv_desc * const ext2fs_vnodeopv_descs[] = {
        &ext2fs_vnodeop_opv_desc,
        &ext2fs_specop_opv_desc,
        &ext2fs_fifoop_opv_desc,
        NULL,
};

struct vfsops ext2fs_vfsops = {
        .vfs_name = MOUNT_EXT2FS,
        .vfs_min_mount_data = sizeof (struct ufs_args),
        .vfs_mount = ext2fs_mount,
        .vfs_start = ufs_start,
        .vfs_unmount = ext2fs_unmount,
        .vfs_root = ufs_root,
        .vfs_quotactl = ufs_quotactl,
        .vfs_statvfs = ext2fs_statvfs,
        .vfs_sync = ext2fs_sync,
        .vfs_vget = ufs_vget,
        .vfs_loadvnode = ext2fs_loadvnode,
        .vfs_newvnode = ext2fs_newvnode,
        .vfs_fhtovp = ext2fs_fhtovp,
        .vfs_vptofh = ext2fs_vptofh,
        .vfs_init = ext2fs_init,
        .vfs_reinit = ext2fs_reinit,
        .vfs_done = ext2fs_done,
        .vfs_mountroot = ext2fs_mountroot,
        .vfs_snapshot = (void *)eopnotsupp,
        .vfs_extattrctl = vfs_stdextattrctl,
        .vfs_suspendctl = genfs_suspendctl,
        .vfs_renamelock_enter = genfs_renamelock_enter,
        .vfs_renamelock_exit = genfs_renamelock_exit,
        .vfs_fsync = (void *)eopnotsupp,
        .vfs_opv_descs = ext2fs_vnodeopv_descs
};

static const struct genfs_ops ext2fs_genfsops = {
        .gop_size = genfs_size,
        .gop_alloc = ext2fs_gop_alloc,
        .gop_write = genfs_gop_write,
        .gop_markupdate = ufs_gop_markupdate,
        .gop_putrange = genfs_gop_putrange,
};

static const struct ufs_ops ext2fs_ufsops = {
        .uo_itimes = ext2fs_itimes,
        .uo_update = ext2fs_update,
        .uo_bufrd = ext2fs_bufrd,
        .uo_bufwr = ext2fs_bufwr,
};

static void
e2fs_cgload(const char *ondisk, struct ext2_gd *inmemory, int cg_size,
    int shift_cg_entry_size)
{

        if (shift_cg_entry_size == 6) {
                memcpy(inmemory, ondisk, cg_size);
                return;
        }

        const char *iptr = ondisk;
        struct ext2_gd *optr = inmemory;
        int sh = 1 << shift_cg_entry_size;
        int lim = cg_size >> shift_cg_entry_size;
        if (shift_cg_entry_size > 6) {
                for (int i = 0; i < lim; i++, optr++, iptr += sh) {
                        memcpy(optr, iptr, sizeof(*optr));
                }
        } else {
                for (int i = 0; i < lim; i++, optr++, iptr += sh) {
                        memcpy(optr, iptr, E2FS_REV0_GD_SIZE);
                        memset((char *)optr + E2FS_REV0_GD_SIZE, 0,
                            sizeof(*optr) - E2FS_REV0_GD_SIZE);
                }
        }
}

static void
e2fs_cgsave(const struct ext2_gd *inmemory, char *ondisk, int cg_size,
    int shift_cg_entry_size)
{

        if (shift_cg_entry_size == 6) {
                memcpy(ondisk, inmemory, cg_size);
                return;
        }

        const struct ext2_gd *iptr = inmemory;
        char *optr = ondisk;
        int sh = 1 << shift_cg_entry_size;
        int lim = cg_size >> shift_cg_entry_size;
        if (shift_cg_entry_size > 6) {
                for (int i = 0; i < lim; i++, iptr++, optr += sh) {
                        memcpy(optr, iptr, sizeof(*iptr));
                        memset(optr + sizeof(*iptr), 0, sh - sizeof(*iptr));
                }
        } else {
                for (int i = 0; i < lim; i++, iptr++, optr += sh) {
                        memcpy(optr, iptr, E2FS_REV0_GD_SIZE);
                }
        }
}

/* Fill in the inode uid/gid from ext2 halves.  */
void
ext2fs_set_inode_guid(struct inode *ip)
{

        ip->i_gid = ip->i_e2fs_gid;
        ip->i_uid = ip->i_e2fs_uid;
        if (ip->i_e2fs->e2fs.e2fs_rev > E2FS_REV0) {
                ip->i_gid |= ip->i_e2fs_gid_high << 16;
                ip->i_uid |= ip->i_e2fs_uid_high << 16;
        }
}

SYSCTL_SETUP(ext2fs_sysctl_setup, "ext2fs sysctl")
{

                sysctl_createv(clog, 0, NULL, NULL,
                               CTLFLAG_PERMANENT,
                               CTLTYPE_NODE, "ext2fs",
                               SYSCTL_DESCR("Linux EXT2FS file system"),
                               NULL, 0, NULL, 0,
                               CTL_VFS, 17, CTL_EOL);
                /*
                 * XXX the "17" above could be dynamic, thereby eliminating
                 * one more instance of the "number to vfs" mapping problem,
                 * but "17" is the order as taken from sys/mount.h
                 */
}

static int
ext2fs_modcmd(modcmd_t cmd, void *arg)
{
        int error;

        switch (cmd) {
        case MODULE_CMD_INIT:
                error = vfs_attach(&ext2fs_vfsops);
                break;
        case MODULE_CMD_FINI:
                error = vfs_detach(&ext2fs_vfsops);
                break;
        default:
                error = ENOTTY;
                break;
        }

        return error;
}

/*
 * XXX Same structure as FFS inodes?  Should we share a common pool?
 */
struct pool ext2fs_inode_pool;

extern u_long ext2gennumber;

void
ext2fs_init(void)
{

        pool_init(&ext2fs_inode_pool, sizeof(struct inode), 0, 0, 0,
            "ext2fsinopl", &pool_allocator_nointr, IPL_NONE);
        ufs_init();
}

void
ext2fs_reinit(void)
{
        ufs_reinit();
}

void
ext2fs_done(void)
{

        ufs_done();
        pool_destroy(&ext2fs_inode_pool);
}

static void
ext2fs_sb_setmountinfo(struct m_ext2fs *fs, struct mount *mp)
{
        (void)strlcpy(fs->e2fs_fsmnt, mp->mnt_stat.f_mntonname,
            sizeof(fs->e2fs_fsmnt));
        if (fs->e2fs_ronly == 0 && fs->e2fs.e2fs_rev > E2FS_REV0) {
                (void)strlcpy(fs->e2fs.e2fs_fsmnt, mp->mnt_stat.f_mntonname,
                    sizeof(fs->e2fs.e2fs_fsmnt));

                fs->e2fs.e2fs_mtime = time_second;
                fs->e2fs.e2fs_mnt_count++;

                fs->e2fs_fmod = 1;
        }
}

/*
 * Called by main() when ext2fs is going to be mounted as root.
 *
 * Name is updated by mount(8) after booting.
 */

int
ext2fs_mountroot(void)
{
        extern struct vnode *rootvp;
        struct m_ext2fs *fs;
        struct mount *mp;
        struct ufsmount *ump;
        int error;

        if (device_class(root_device) != DV_DISK)
                return ENODEV;

        if ((error = vfs_rootmountalloc(MOUNT_EXT2FS, "root_device", &mp))) {
                vrele(rootvp);
                return error;
        }

        if ((error = ext2fs_mountfs(rootvp, mp)) != 0) {
                vfs_unbusy(mp);
                vfs_rele(mp);
                return error;
        }
        mountlist_append(mp);
        ump = VFSTOUFS(mp);
        fs = ump->um_e2fs;
        ext2fs_sb_setmountinfo(fs, mp);
        (void)ext2fs_statvfs(mp, &mp->mnt_stat);
        vfs_unbusy(mp);
        setrootfstime((time_t)fs->e2fs.e2fs_wtime);
        return 0;
}

/*
 * VFS Operations.
 *
 * mount system call
 */
int
ext2fs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
{
        struct lwp *l = curlwp;
        struct vnode *devvp;
        struct ufs_args *args = data;
        struct ufsmount *ump = NULL;
        struct m_ext2fs *fs;
        int error = 0, flags, update;
        mode_t accessmode;

        if (args == NULL)
                return EINVAL;
        if (*data_len < sizeof *args)
                return EINVAL;

        if (mp->mnt_flag & MNT_GETARGS) {
                ump = VFSTOUFS(mp);
                if (ump == NULL)
                        return EIO;
                memset(args, 0, sizeof *args);
                args->fspec = NULL;
                *data_len = sizeof *args;
                return 0;
        }

        update = mp->mnt_flag & MNT_UPDATE;

        /* Check arguments */
        if (args->fspec != NULL) {
                /*
                 * Look up the name and verify that it's sane.
                 */
                error = namei_simple_user(args->fspec,
                                        NSM_FOLLOW_NOEMULROOT, &devvp);
                if (error != 0)
                        return error;

                if (!update) {
                        /*
                         * Be sure this is a valid block device
                         */
                        if (devvp->v_type != VBLK)
                                error = ENOTBLK;
                        else if (bdevsw_lookup(devvp->v_rdev) == NULL)
                                error = ENXIO;
                } else {
                        /*
                         * Be sure we're still naming the same device
                         * used for our initial mount
                         */
                        ump = VFSTOUFS(mp);
                        if (devvp != ump->um_devvp) {
                                if (devvp->v_rdev != ump->um_devvp->v_rdev)
                                        error = EINVAL;
                                else {
                                        vrele(devvp);
                                        devvp = ump->um_devvp;
                                        vref(devvp);
                                }
                        }
                }
        } else {
                if (!update) {
                        /* New mounts must have a filename for the device */
                        return EINVAL;
                } else {
                        ump = VFSTOUFS(mp);
                        devvp = ump->um_devvp;
                        vref(devvp);
                }
        }

        /*
         * If mount by non-root, then verify that user has necessary
         * permissions on the device.
         *
         * Permission to update a mount is checked higher, so here we presume
         * updating the mount is okay (for example, as far as securelevel goes)
         * which leaves us with the normal check.
         */
        if (error == 0) {
                accessmode = VREAD;
                if (update ?
                    (mp->mnt_iflag & IMNT_WANTRDWR) != 0 :
                    (mp->mnt_flag & MNT_RDONLY) == 0)
                        accessmode |= VWRITE;
                vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
                error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_MOUNT,
                    KAUTH_REQ_SYSTEM_MOUNT_DEVICE, mp, devvp,
                    KAUTH_ARG(accessmode));
                VOP_UNLOCK(devvp);
        }

        if (error) {
                vrele(devvp);
                return error;
        }

        if (!update) {
                int xflags;

                if (mp->mnt_flag & MNT_RDONLY)
                        xflags = FREAD;
                else
                        xflags = FREAD|FWRITE;
                vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
                error = VOP_OPEN(devvp, xflags, FSCRED);
                VOP_UNLOCK(devvp);
                if (error)
                        goto fail;
                error = ext2fs_mountfs(devvp, mp);
                if (error) {
                        vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
                        (void)VOP_CLOSE(devvp, xflags, NOCRED);
                        VOP_UNLOCK(devvp);
                        goto fail;
                }

                ump = VFSTOUFS(mp);
                fs = ump->um_e2fs;
        } else {
                /*
                 * Update the mount.
                 */

                /*
                 * The initial mount got a reference on this
                 * device, so drop the one obtained via
                 * namei(), above.
                 */
                vrele(devvp);

                ump = VFSTOUFS(mp);
                fs = ump->um_e2fs;
                if (fs->e2fs_ronly == 0 && (mp->mnt_flag & MNT_RDONLY)) {
                        /*
                         * Changing from r/w to r/o
                         */
                        flags = WRITECLOSE;
                        if (mp->mnt_flag & MNT_FORCE)
                                flags |= FORCECLOSE;
                        error = ext2fs_flushfiles(mp, flags);
                        if (error == 0 &&
                            ext2fs_cgupdate(ump, MNT_WAIT) == 0 &&
                            (fs->e2fs.e2fs_state & E2FS_ERRORS) == 0) {
                                fs->e2fs.e2fs_state = E2FS_ISCLEAN;
                                (void) ext2fs_sbupdate(ump, MNT_WAIT);
                        }
                        if (error)
                                return error;
                        fs->e2fs_ronly = 1;
                }

                if (mp->mnt_flag & MNT_RELOAD) {
                        error = ext2fs_reload(mp, l->l_cred, l);
                        if (error)
                                return error;
                }

                if (fs->e2fs_ronly && (mp->mnt_iflag & IMNT_WANTRDWR)) {
                        /*
                         * Changing from read-only to read/write
                         */
                        fs->e2fs_ronly = 0;
                        if (fs->e2fs.e2fs_state == E2FS_ISCLEAN)
                                fs->e2fs.e2fs_state = 0;
                        else
                                fs->e2fs.e2fs_state = E2FS_ERRORS;
                        fs->e2fs_fmod = 1;
                }
                if (args->fspec == NULL)
                        return 0;
        }

        error = set_statvfs_info(path, UIO_USERSPACE, args->fspec,
            UIO_USERSPACE, mp->mnt_op->vfs_name, mp, l);
        if (error == 0)
                ext2fs_sb_setmountinfo(fs, mp);

        if (fs->e2fs_fmod != 0) {       /* XXX */
                fs->e2fs_fmod = 0;
                if (fs->e2fs.e2fs_state == 0)
                        fs->e2fs.e2fs_wtime = time_second;
                else
                        printf("%s: file system not clean; please fsck(8)\n",
                                mp->mnt_stat.f_mntfromname);
                (void) ext2fs_cgupdate(ump, MNT_WAIT);
        }
        return error;

fail:
        vrele(devvp);
        return error;
}

/*
 * Sanity check the disk vnode content, and copy it over to inode structure.
 */
static int
ext2fs_loadvnode_content(struct m_ext2fs *fs, ino_t ino, struct buf *bp, struct inode *ip)
{
        struct ext2fs_dinode *din;
        int error = 0;

        din = (struct ext2fs_dinode *)((char *)bp->b_data +
            (ino_to_fsbo(fs, ino) * EXT2_DINODE_SIZE(fs)));

        /* sanity checks - inode data NOT byteswapped at this point */
        if (EXT2_DINODE_FITS(din, e2di_extra_isize, EXT2_DINODE_SIZE(fs))
            && (EXT2_DINODE_SIZE(fs) - EXT2_REV0_DINODE_SIZE)
            < fs2h16(din->e2di_extra_isize))
        {
                printf("ext2fs: inode %"PRIu64" bad extra_isize %u",
                        ino, din->e2di_extra_isize);
                error = EINVAL;
                goto bad;
        }

        /* everything alright, proceed with copy */
        if (ip->i_din.e2fs_din == NULL)
                ip->i_din.e2fs_din = kmem_alloc(EXT2_DINODE_SIZE(fs), KM_SLEEP);

        e2fs_iload(din, ip->i_din.e2fs_din, EXT2_DINODE_SIZE(fs));

        ext2fs_set_inode_guid(ip);

    bad:
        return error;
}

/*
 * Reload all incore data for a filesystem (used after running fsck on
 * the root filesystem and finding things to fix). The filesystem must
 * be mounted read-only.
 *
 * Things to do to update the mount:
 *      1) invalidate all cached meta-data.
 *      2) re-read superblock from disk.
 *      3) re-read summary information from disk.
 *      4) invalidate all inactive vnodes.
 *      5) invalidate all cached file data.
 *      6) re-read inode data for all active vnodes.
 */
int
ext2fs_reload(struct mount *mp, kauth_cred_t cred, struct lwp *l)
{
        struct vnode *vp, *devvp;
        struct inode *ip;
        struct buf *bp;
        struct m_ext2fs *fs;
        struct ext2fs *newfs;
        int i, error;
        struct ufsmount *ump;
        struct vnode_iterator *marker;

        if ((mp->mnt_flag & MNT_RDONLY) == 0)
                return EINVAL;

        ump = VFSTOUFS(mp);
        /*
         * Step 1: invalidate all cached meta-data.
         */
        devvp = ump->um_devvp;
        vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
        error = vinvalbuf(devvp, 0, cred, l, 0, 0);
        VOP_UNLOCK(devvp);
        if (error)
                panic("ext2fs_reload: dirty1");

        fs = ump->um_e2fs;
        /*
         * Step 2: re-read superblock from disk. Copy in new superblock, and
         * compute in-memory values.
         */
        error = bread(devvp, SBLOCK, SBSIZE, 0, &bp);
        if (error)
                return error;
        newfs = (struct ext2fs *)bp->b_data;
        e2fs_sbload(newfs, &fs->e2fs);

        brelse(bp, 0);

        error = ext2fs_sbfill(fs, (mp->mnt_flag & MNT_RDONLY) != 0);
        if (error)
                return error;

        /*
         * Step 3: re-read summary information from disk.
         */
        for (i = 0; i < fs->e2fs_ngdb; i++) {
                error = bread(devvp ,
                    EXT2_FSBTODB(fs, fs->e2fs.e2fs_first_dblock +
                    1 /* superblock */ + i),
                    fs->e2fs_bsize, 0, &bp);
                if (error) {
                        return error;
                }
                e2fs_cgload(bp->b_data,
                    &fs->e2fs_gd[i *
                        (fs->e2fs_bsize >> fs->e2fs_group_desc_shift)],
                    fs->e2fs_bsize, fs->e2fs_group_desc_shift);
                brelse(bp, 0);
        }

        vfs_vnode_iterator_init(mp, &marker);
        while ((vp = vfs_vnode_iterator_next(marker, NULL, NULL))) {
                /*
                 * Step 4: invalidate all inactive vnodes.
                 */
                if (vrecycle(vp))
                        continue;
                /*
                 * Step 5: invalidate all cached file data.
                 */
                if (vn_lock(vp, LK_EXCLUSIVE)) {
                        vrele(vp);
                        continue;
                }
                if (vinvalbuf(vp, 0, cred, l, 0, 0))
                        panic("ext2fs_reload: dirty2");
                /*
                 * Step 6: re-read inode data for all active vnodes.
                 */
                ip = VTOI(vp);
                error = bread(devvp, EXT2_FSBTODB(fs, ino_to_fsba(fs, ip->i_number)),
                    (int)fs->e2fs_bsize, 0, &bp);
                if (error) {
                        vput(vp);
                        break;
                }
                error = ext2fs_loadvnode_content(fs, ip->i_number, bp, ip);
                brelse(bp, 0);
                if (error) {
                        vput(vp);
                        break;
                }

                vput(vp);
        }
        vfs_vnode_iterator_destroy(marker);
        return error;
}

/*
 * Common code for mount and mountroot
 */
int
ext2fs_mountfs(struct vnode *devvp, struct mount *mp)
{
        struct lwp *l = curlwp;
        struct ufsmount *ump;
        struct buf *bp;
        struct ext2fs *fs;
        struct m_ext2fs *m_fs;
        dev_t dev;
        int error, i, ronly;
        kauth_cred_t cred;

        dev = devvp->v_rdev;
        cred = l->l_cred;

        /* Flush out any old buffers remaining from a previous use. */
        vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
        error = vinvalbuf(devvp, V_SAVE, cred, l, 0, 0);
        VOP_UNLOCK(devvp);
        if (error)
                return error;

        ronly = (mp->mnt_flag & MNT_RDONLY) != 0;

        bp = NULL;
        ump = NULL;

        /* Read the superblock from disk, and swap it directly. */
        error = bread(devvp, SBLOCK, SBSIZE, 0, &bp);
        if (error)
                goto out;
        fs = (struct ext2fs *)bp->b_data;
        m_fs = kmem_zalloc(sizeof(*m_fs), KM_SLEEP);
        e2fs_sbload(fs, &m_fs->e2fs);

        brelse(bp, 0);
        bp = NULL;

        /* Once swapped, validate and fill in the superblock. */
        error = ext2fs_sbfill(m_fs, ronly);
        if (error) {
                kmem_free(m_fs, sizeof(*m_fs));
                goto out;
        }
        m_fs->e2fs_ronly = ronly;

        ump = kmem_zalloc(sizeof(*ump), KM_SLEEP);
        ump->um_fstype = UFS1;
        ump->um_ops = &ext2fs_ufsops;
        ump->um_e2fs = m_fs;

        if (ronly == 0) {
                if (m_fs->e2fs.e2fs_state == E2FS_ISCLEAN)
                        m_fs->e2fs.e2fs_state = 0;
                else
                        m_fs->e2fs.e2fs_state = E2FS_ERRORS;
                m_fs->e2fs_fmod = 1;
        }

        int32_t sh = m_fs->e2fs_bsize >> m_fs->e2fs_group_desc_shift;
        /* XXX: should be added in ext2fs_sbfill()? */
        m_fs->e2fs_gd = kmem_alloc(m_fs->e2fs_ngdb * sh
            * sizeof(struct ext2_gd), KM_SLEEP);
        for (i = 0; i < m_fs->e2fs_ngdb; i++) {
                error = bread(devvp,
                    EXT2_FSBTODB(m_fs, m_fs->e2fs.e2fs_first_dblock +
                    1 /* superblock */ + i),
                    m_fs->e2fs_bsize, 0, &bp);
                if (error)
                        goto out1;
                e2fs_cgload(bp->b_data, &m_fs->e2fs_gd[i *
                        (m_fs->e2fs_bsize >> m_fs->e2fs_group_desc_shift)],
                    m_fs->e2fs_bsize, m_fs->e2fs_group_desc_shift);
                brelse(bp, 0);
                bp = NULL;
        }

        error = ext2fs_cg_verify_and_initialize(devvp, m_fs, ronly);
        if (error)
                goto out1;

        mp->mnt_data = ump;
        mp->mnt_stat.f_fsidx.__fsid_val[0] = (long)dev;
        mp->mnt_stat.f_fsidx.__fsid_val[1] = makefstype(MOUNT_EXT2FS);
        mp->mnt_stat.f_fsid = mp->mnt_stat.f_fsidx.__fsid_val[0];
        mp->mnt_stat.f_namemax = EXT2FS_MAXNAMLEN;
        mp->mnt_flag |= MNT_LOCAL;
        mp->mnt_dev_bshift = DEV_BSHIFT;        /* XXX */
        mp->mnt_fs_bshift = m_fs->e2fs_bshift;
        mp->mnt_iflag |= IMNT_DTYPE | IMNT_SHRLOOKUP;
        ump->um_flags = 0;
        ump->um_mountp = mp;
        ump->um_dev = dev;
        ump->um_devvp = devvp;
        ump->um_nindir = EXT2_NINDIR(m_fs);
        ump->um_lognindir = ffs(EXT2_NINDIR(m_fs)) - 1;
        ump->um_bptrtodb = m_fs->e2fs_fsbtodb;
        ump->um_seqinc = 1; /* no frags */
        ump->um_maxsymlinklen = EXT2_MAXSYMLINKLEN;
        ump->um_dirblksiz = m_fs->e2fs_bsize;
        ump->um_maxfilesize = ((uint64_t)0x80000000 * m_fs->e2fs_bsize - 1);
        spec_node_setmountedfs(devvp, mp);
        return 0;

out1:
        kmem_free(m_fs->e2fs_gd, m_fs->e2fs_ngdb * sh * sizeof(struct ext2_gd));
out:
        if (bp != NULL)
                brelse(bp, 0);
        if (ump) {
                kmem_free(ump->um_e2fs, sizeof(*m_fs));
                kmem_free(ump, sizeof(*ump));
                mp->mnt_data = NULL;
        }
        return error;
}

/*
 * unmount system call
 */
int
ext2fs_unmount(struct mount *mp, int mntflags)
{
        struct ufsmount *ump;
        struct m_ext2fs *fs;
        int error, flags;

        flags = 0;
        if (mntflags & MNT_FORCE)
                flags |= FORCECLOSE;
        if ((error = ext2fs_flushfiles(mp, flags)) != 0)
                return error;
        ump = VFSTOUFS(mp);
        fs = ump->um_e2fs;
        if (fs->e2fs_ronly == 0 &&
                ext2fs_cgupdate(ump, MNT_WAIT) == 0 &&
                (fs->e2fs.e2fs_state & E2FS_ERRORS) == 0) {
                fs->e2fs.e2fs_state = E2FS_ISCLEAN;
                (void) ext2fs_sbupdate(ump, MNT_WAIT);
        }
        if (ump->um_devvp->v_type != VBAD)
                spec_node_setmountedfs(ump->um_devvp, NULL);
        vn_lock(ump->um_devvp, LK_EXCLUSIVE | LK_RETRY);
        error = VOP_CLOSE(ump->um_devvp, fs->e2fs_ronly ? FREAD : FREAD|FWRITE,
            NOCRED);
        vput(ump->um_devvp);
        int32_t sh = fs->e2fs_bsize >> fs->e2fs_group_desc_shift;
        kmem_free(fs->e2fs_gd, fs->e2fs_ngdb * sh * sizeof(struct ext2_gd));
        kmem_free(fs, sizeof(*fs));
        kmem_free(ump, sizeof(*ump));
        mp->mnt_data = NULL;
        mp->mnt_flag &= ~MNT_LOCAL;
        return error;
}

/*
 * Flush out all the files in a filesystem.
 */
int
ext2fs_flushfiles(struct mount *mp, int flags)
{
        extern int doforce;
        int error;

        if (!doforce)
                flags &= ~FORCECLOSE;
        error = vflush(mp, NULLVP, flags);
        return error;
}

/*
 * Get file system statistics.
 */
int
ext2fs_statvfs(struct mount *mp, struct statvfs *sbp)
{
        struct ufsmount *ump;
        struct m_ext2fs *fs;
        uint32_t overhead, overhead_per_group, ngdb;
        int i, ngroups;

        ump = VFSTOUFS(mp);
        fs = ump->um_e2fs;
        if (fs->e2fs.e2fs_magic != E2FS_MAGIC)
                panic("ext2fs_statvfs");

        /*
         * Compute the overhead (FS structures)
         */
        overhead_per_group =
            1 /* block bitmap */ +
            1 /* inode bitmap */ +
            fs->e2fs_itpg;
        overhead = fs->e2fs.e2fs_first_dblock +
            fs->e2fs_ncg * overhead_per_group;
        if (EXT2F_HAS_COMPAT_FEATURE(fs, EXT2F_COMPAT_SPARSESUPER2)) {
                /*
                 * Superblock and group descriptions is in group zero,
                 * then optionally 0, 1 or 2 extra copies.
                 */
                ngroups = 1
                        + (fs->e2fs.e4fs_backup_bgs[0] ? 1 : 0)
                        + (fs->e2fs.e4fs_backup_bgs[1] ? 1 : 0);
        } else if (EXT2F_HAS_ROCOMPAT_FEATURE(fs, EXT2F_ROCOMPAT_SPARSESUPER)) {
                for (i = 0, ngroups = 0; i < fs->e2fs_ncg; i++) {
                        if (cg_has_sb(i))
                                ngroups++;
                }
        } else {
                ngroups = fs->e2fs_ncg;
        }
        ngdb = fs->e2fs_ngdb;
        if (EXT2F_HAS_COMPAT_FEATURE(fs, EXT2F_COMPAT_RESIZE))
                ngdb += fs->e2fs.e2fs_reserved_ngdb;
        overhead += ngroups * (1 /* superblock */ + ngdb);

        sbp->f_bsize = fs->e2fs_bsize;
        sbp->f_frsize = MINBSIZE << fs->e2fs.e2fs_fsize;
        sbp->f_iosize = fs->e2fs_bsize;
        sbp->f_blocks = fs->e2fs.e2fs_bcount - overhead;
        sbp->f_bfree = fs->e2fs.e2fs_fbcount;
        sbp->f_bresvd = fs->e2fs.e2fs_rbcount;
        if (sbp->f_bfree > sbp->f_bresvd)
                sbp->f_bavail = sbp->f_bfree - sbp->f_bresvd;
        else
                sbp->f_bavail = 0;
        sbp->f_files =  fs->e2fs.e2fs_icount;
        sbp->f_ffree = fs->e2fs.e2fs_ficount;
        sbp->f_favail = fs->e2fs.e2fs_ficount;
        sbp->f_fresvd = 0;
        copy_statvfs_info(sbp, mp);
        return 0;
}

static bool
ext2fs_sync_selector(void *cl, struct vnode *vp)
{
        struct inode *ip;

        KASSERT(mutex_owned(vp->v_interlock));

        ip = VTOI(vp);
        /*
         * Skip the vnode/inode if inaccessible.
         */
        if (ip == NULL || vp->v_type == VNON)
                return false;

        if (((ip->i_flag &
              (IN_CHANGE | IN_UPDATE | IN_MODIFIED)) == 0 &&
             LIST_EMPTY(&vp->v_dirtyblkhd) &&
             (vp->v_iflag & VI_ONWORKLST) == 0))
                return false;
        return true;
}

/*
 * Go through the disk queues to initiate sandbagged IO;
 * go through the inodes to write those that have been modified;
 * initiate the writing of the super block if it has been modified.
 */
int
ext2fs_sync(struct mount *mp, int waitfor, kauth_cred_t cred)
{
        struct vnode *vp;
        struct ufsmount *ump = VFSTOUFS(mp);
        struct m_ext2fs *fs;
        struct vnode_iterator *marker;
        int error, allerror = 0;

        fs = ump->um_e2fs;
        if (fs->e2fs_fmod != 0 && fs->e2fs_ronly != 0) {        /* XXX */
                printf("fs = %s\n", fs->e2fs_fsmnt);
                panic("update: rofs mod");
        }

        /*
         * Write back each (modified) inode.
         */
        vfs_vnode_iterator_init(mp, &marker);
        while ((vp = vfs_vnode_iterator_next(marker, ext2fs_sync_selector,
            NULL)))
        {
                error = vn_lock(vp, LK_EXCLUSIVE);
                if (error) {
                        vrele(vp);
                        continue;
                }
                if (vp->v_type == VREG && waitfor == MNT_LAZY)
                        error = ext2fs_update(vp, NULL, NULL, 0);
                else
                        error = VOP_FSYNC(vp, cred,
                            waitfor == MNT_WAIT ? FSYNC_WAIT : 0, 0, 0);
                if (error)
                        allerror = error;
                vput(vp);
        }
        vfs_vnode_iterator_destroy(marker);
        /*
         * Force stale file system control information to be flushed.
         */
        if (waitfor != MNT_LAZY) {
                vn_lock(ump->um_devvp, LK_EXCLUSIVE | LK_RETRY);
                if ((error = VOP_FSYNC(ump->um_devvp, cred,
                    waitfor == MNT_WAIT ? FSYNC_WAIT : 0, 0, 0)) != 0)
                        allerror = error;
                VOP_UNLOCK(ump->um_devvp);
        }
        /*
         * Write back modified superblock.
         */
        if (fs->e2fs_fmod != 0) {
                fs->e2fs_fmod = 0;
                fs->e2fs.e2fs_wtime = time_second;
                if ((error = ext2fs_cgupdate(ump, waitfor)))
                        allerror = error;
        }
        return allerror;
}

/*
 * Load inode from disk and initialize vnode.
 */
static int
ext2fs_init_vnode(struct ufsmount *ump, struct vnode *vp, ino_t ino)
{
        struct m_ext2fs *fs;
        struct inode *ip;
        struct buf *bp;
        int error;

        fs = ump->um_e2fs;

        /* Read in the disk contents for the inode, copy into the inode. */
        error = bread(ump->um_devvp, EXT2_FSBTODB(fs, ino_to_fsba(fs, ino)),
            (int)fs->e2fs_bsize, 0, &bp);
        if (error)
                return error;

        /* Allocate and initialize inode. */
        ip = pool_get(&ext2fs_inode_pool, PR_WAITOK);
        memset(ip, 0, sizeof(struct inode));
        ip->i_vnode = vp;
        ip->i_ump = ump;
        ip->i_e2fs = fs;
        ip->i_dev = ump->um_dev;
        ip->i_number = ino;
        ip->i_e2fs_last_lblk = 0;
        ip->i_e2fs_last_blk = 0;

        error = ext2fs_loadvnode_content(fs, ino, bp, ip);
        brelse(bp, 0);
        if (error) {
                pool_put(&ext2fs_inode_pool, ip);
                return error;
        }

        /* If the inode was deleted, reset all fields */
        if (ip->i_e2fs_dtime != 0) {
                ip->i_e2fs_mode = 0;
                (void)ext2fs_setsize(ip, 0);
                (void)ext2fs_setnblock(ip, 0);
                memset(ip->i_e2fs_blocks, 0, sizeof(ip->i_e2fs_blocks));
        }

        /* Initialise vnode with this inode. */
        vp->v_tag = VT_EXT2FS;
        vp->v_op = ext2fs_vnodeop_p;
        vp->v_data = ip;

        /* Initialize genfs node. */
        genfs_node_init(vp, &ext2fs_genfsops);

        return 0;
}

/*
 * Read an inode from disk and initialize this vnode / inode pair.
 * Caller assures no other thread will try to load this inode.
 */
int
ext2fs_loadvnode(struct mount *mp, struct vnode *vp,
    const void *key, size_t key_len, const void **new_key)
{
        ino_t ino;
        struct inode *ip;
        struct ufsmount *ump;
        int error;

        KASSERT(key_len == sizeof(ino));
        memcpy(&ino, key, key_len);
        ump = VFSTOUFS(mp);

        error = ext2fs_init_vnode(ump, vp, ino);
        if (error)
                return error;

        ip = VTOI(vp);

        /* Initialize the vnode from the inode. */
        ext2fs_vinit(mp, ext2fs_specop_p, ext2fs_fifoop_p, &vp);

        /* Finish inode initialization. */
        ip->i_devvp = ump->um_devvp;
        vref(ip->i_devvp);

        /*
         * Set up a generation number for this inode if it does not
         * already have one. This should only happen on old filesystems.
         */

        if (ip->i_e2fs_gen == 0) {
                if (++ext2gennumber < (u_long)time_second)
                        ext2gennumber = time_second;
                ip->i_e2fs_gen = ext2gennumber;
                if ((mp->mnt_flag & MNT_RDONLY) == 0)
                        ip->i_flag |= IN_MODIFIED;
        }
        uvm_vnp_setsize(vp, ext2fs_size(ip));
        *new_key = &ip->i_number;
        return 0;
}

/*
 * Create a new inode on disk and initialize this vnode / inode pair.
 */
int
ext2fs_newvnode(struct mount *mp, struct vnode *dvp, struct vnode *vp,
    struct vattr *vap, kauth_cred_t cred, void *extra,
    size_t *key_len, const void **new_key)
{
        ino_t ino;
        struct inode *ip, *pdir;
        struct m_ext2fs *fs;
        struct ufsmount *ump;
        int error, mode;

        KASSERT(dvp->v_mount == mp);
        KASSERT(vap->va_type != VNON);

        *key_len = sizeof(ino);

        pdir = VTOI(dvp);
        fs = pdir->i_e2fs;
        ump = VFSTOUFS(mp);
        mode = MAKEIMODE(vap->va_type, vap->va_mode);

        /* Allocate fresh inode. */
        error = ext2fs_valloc(dvp, mode, cred, &ino);
        if (error)
                return error;

        /* Attach inode to vnode. */
        error = ext2fs_init_vnode(ump, vp, ino);
        if (error) {
                ext2fs_vfree(dvp, ino, mode);
                return error;
        }

        ip = VTOI(vp);

        KASSERT(!E2FS_HAS_GD_CSUM(fs) ||
            (fs->e2fs_gd[ino_to_cg(fs, ino)].ext2bgd_flags &
            h2fs16(E2FS_BG_INODE_ZEROED)) != 0);

        /* check for already used inode; makes sense only for ZEROED itable */
        if (__predict_false(ip->i_e2fs_mode && ip->i_e2fs_nlink != 0)) {
                printf("mode = 0%o, nlinks %d, inum = %llu, fs = %s\n",
                    ip->i_e2fs_mode, ip->i_e2fs_nlink,
                    (unsigned long long)ip->i_number, fs->e2fs_fsmnt);
                panic("ext2fs_valloc: dup alloc");
        }

        memset(ip->i_din.e2fs_din, 0, EXT2_DINODE_SIZE(fs));

        /*
         * Set up a new generation number for this inode.
         */
        if (++ext2gennumber < time_second)
                ext2gennumber = time_second;
        ip->i_e2fs_gen = ext2gennumber;

        ip->i_uid = kauth_cred_geteuid(cred);
        ip->i_e2fs_uid = ip->i_uid & 0xffff;
        ip->i_e2fs_gid = pdir->i_e2fs_gid;
        if (ip->i_e2fs->e2fs.e2fs_rev > E2FS_REV0) {
                ip->i_e2fs_uid_high = (ip->i_uid >> 16) & 0xffff;
                ip->i_e2fs_gid_high = pdir->i_e2fs_gid_high;
        } else {
                ip->i_e2fs_uid_high = 0;
                ip->i_e2fs_gid_high = 0;
        }
        ip->i_gid = ip->i_e2fs_gid | (ip->i_e2fs_gid_high << 16);
        ip->i_flag |= IN_ACCESS | IN_CHANGE | IN_UPDATE;
        ip->i_e2fs_mode = mode;
        vp->v_type = IFTOVT(mode);
        ip->i_e2fs_nlink = 1;

        /* Authorize setting SGID if needed. */
        if (ip->i_e2fs_mode & ISGID) {
                error = kauth_authorize_vnode(cred, KAUTH_VNODE_WRITE_SECURITY,
                    vp, NULL, genfs_can_chmod(vp, cred, ip->i_uid, ip->i_gid,
                    mode));
                if (error)
                        ip->i_e2fs_mode &= ~ISGID;
        }

        /* Initialize extra_isize according to what is set in superblock */
        if (EXT2F_HAS_ROCOMPAT_FEATURE(ip->i_e2fs, EXT2F_ROCOMPAT_EXTRA_ISIZE)
            && EXT2_DINODE_SIZE(ip->i_e2fs) > EXT2_REV0_DINODE_SIZE) {
                ip->i_din.e2fs_din->e2di_extra_isize =
                    ip->i_e2fs->e2fs.e4fs_want_extra_isize;
        }

        /* Set create time if possible */
        if (EXT2_DINODE_FITS(ip->i_din.e2fs_din, e2di_crtime,
            EXT2_DINODE_SIZE(ip->i_e2fs))) {
                struct timespec now;
                vfs_timestamp(&now);
                EXT2_DINODE_TIME_SET(&now, ip->i_din.e2fs_din, e2di_crtime,
                    EXT2_DINODE_SIZE(ip->i_e2fs));
        }

        /* Initialize the vnode from the inode. */
        ext2fs_vinit(mp, ext2fs_specop_p, ext2fs_fifoop_p, &vp);

        /* Finish inode initialization. */
        ip->i_devvp = ump->um_devvp;
        vref(ip->i_devvp);

        uvm_vnp_setsize(vp, ext2fs_size(ip));
        *new_key = &ip->i_number;
        return 0;
}

/*
 * File handle to vnode
 *
 * Have to be really careful about stale file handles:
 * - check that the inode number is valid
 * - call ext2fs_vget() to get the locked inode
 * - check for an unallocated inode (i_mode == 0)
 */
int
ext2fs_fhtovp(struct mount *mp, struct fid *fhp, int lktype, struct vnode **vpp)
{
        struct inode *ip;
        struct vnode *nvp;
        int error;
        struct ufid ufh;
        struct m_ext2fs *fs;

        if (fhp->fid_len != sizeof(struct ufid))
                return EINVAL;

        memcpy(&ufh, fhp, sizeof(struct ufid));
        fs = VFSTOUFS(mp)->um_e2fs;
        if ((ufh.ufid_ino < EXT2_FIRSTINO && ufh.ufid_ino != EXT2_ROOTINO) ||
                ufh.ufid_ino >= fs->e2fs_ncg * fs->e2fs.e2fs_ipg)
                return ESTALE;

        if ((error = VFS_VGET(mp, ufh.ufid_ino, lktype, &nvp)) != 0) {
                *vpp = NULLVP;
                return error;
        }
        ip = VTOI(nvp);
        if (ip->i_e2fs_mode == 0 || ip->i_e2fs_dtime != 0 ||
                ip->i_e2fs_gen != ufh.ufid_gen) {
                vput(nvp);
                *vpp = NULLVP;
                return ESTALE;
        }
        *vpp = nvp;
        return 0;
}

/*
 * Vnode pointer to File handle
 */
/* ARGSUSED */
int
ext2fs_vptofh(struct vnode *vp, struct fid *fhp, size_t *fh_size)
{
        struct inode *ip;
        struct ufid ufh;

        if (*fh_size < sizeof(struct ufid)) {
                *fh_size = sizeof(struct ufid);
                return E2BIG;
        }
        *fh_size = sizeof(struct ufid);

        ip = VTOI(vp);
        memset(&ufh, 0, sizeof(ufh));
        ufh.ufid_len = sizeof(struct ufid);
        ufh.ufid_ino = ip->i_number;
        ufh.ufid_gen = ip->i_e2fs_gen;
        memcpy(fhp, &ufh, sizeof(ufh));
        return 0;
}

/*
 * Write a superblock and associated information back to disk.
 */
int
ext2fs_sbupdate(struct ufsmount *mp, int waitfor)
{
        struct m_ext2fs *fs = mp->um_e2fs;
        struct buf *bp;
        int error = 0;

        bp = getblk(mp->um_devvp, SBLOCK, SBSIZE, 0, 0);
        e2fs_sbsave(&fs->e2fs, (struct ext2fs*)bp->b_data);
        if (waitfor == MNT_WAIT)
                error = bwrite(bp);
        else
                bawrite(bp);
        return error;
}

int
ext2fs_cgupdate(struct ufsmount *mp, int waitfor)
{
        struct m_ext2fs *fs = mp->um_e2fs;
        struct buf *bp;
        int i, error = 0, allerror = 0;

        allerror = ext2fs_sbupdate(mp, waitfor);
        for (i = 0; i < fs->e2fs_ngdb; i++) {
                bp = getblk(mp->um_devvp, EXT2_FSBTODB(fs,
                    fs->e2fs.e2fs_first_dblock +
                    1 /* superblock */ + i), fs->e2fs_bsize, 0, 0);
                e2fs_cgsave(&fs->e2fs_gd[i *
                        (fs->e2fs_bsize >> fs->e2fs_group_desc_shift)],
                    bp->b_data, fs->e2fs_bsize, fs->e2fs_group_desc_shift);
                if (waitfor == MNT_WAIT)
                        error = bwrite(bp);
                else
                        bawrite(bp);
        }

        if (!allerror && error)
                allerror = error;
        return allerror;
}

/*
 * Fill in the m_fs structure, and validate the fields of the superblock.
 * NOTE: here, the superblock is already swapped.
 */
static int
ext2fs_sbfill(struct m_ext2fs *m_fs, int ronly)
{
        uint32_t u32;
        struct ext2fs *fs = &m_fs->e2fs;

        /*
         * General sanity checks
         */
        if (fs->e2fs_magic != E2FS_MAGIC)
                return EINVAL;
        if (fs->e2fs_rev > E2FS_REV1) {
                printf("ext2fs: unsupported revision number: %#x\n",
                    fs->e2fs_rev);
                return EINVAL;
        }
        if (fs->e2fs_log_bsize > 2) {
                /* block size = 1024|2048|4096 */
                printf("ext2fs: bad block size: %d\n", fs->e2fs_log_bsize);
                return EINVAL;
        }
        if (fs->e2fs_bpg == 0) {
                printf("ext2fs: zero blocks per group\n");
                return EINVAL;
        }
        if (fs->e2fs_ipg == 0) {
                printf("ext2fs: zero inodes per group\n");
                return EINVAL;
        }

        if (fs->e2fs_first_dblock >= fs->e2fs_bcount) {
                printf("ext2fs: invalid first data block\n");
                return EINVAL;
        }
        if (fs->e2fs_rbcount > fs->e2fs_bcount ||
            fs->e2fs_fbcount > fs->e2fs_bcount) {
                printf("ext2fs: invalid block count\n");
                return EINVAL;
        }

        /*
         * Compute the fields of the superblock
         */
        u32 = fs->e2fs_bcount - fs->e2fs_first_dblock; /* > 0 */
        m_fs->e2fs_ncg = howmany(u32, fs->e2fs_bpg);
        if (m_fs->e2fs_ncg == 0) {
                printf("ext2fs: invalid number of cylinder groups\n");
                return EINVAL;
        }

        m_fs->e2fs_fsbtodb = fs->e2fs_log_bsize + LOG_MINBSIZE - DEV_BSHIFT;
        m_fs->e2fs_bsize = MINBSIZE << fs->e2fs_log_bsize;
        m_fs->e2fs_bshift = LOG_MINBSIZE + fs->e2fs_log_bsize;
        m_fs->e2fs_qbmask = m_fs->e2fs_bsize - 1;
        m_fs->e2fs_bmask = ~m_fs->e2fs_qbmask;

        if (!(fs->e2fs_features_incompat & EXT2F_INCOMPAT_64BIT) ||
            (fs->e2fs_rev == E2FS_REV0))
                m_fs->e2fs_group_desc_shift = 5;
        else {
                for (m_fs->e2fs_group_desc_shift = 0;
                     (1 << m_fs->e2fs_group_desc_shift)
                       < fs->e3fs_desc_size;
                     m_fs->e2fs_group_desc_shift++);
        }

        if ((u32 = (m_fs->e2fs_bsize >> m_fs->e2fs_group_desc_shift)) == 0) {
                /* Unlikely to happen */
                printf("ext2fs: invalid block size\n");
                return EINVAL;
        }
        m_fs->e2fs_ngdb = howmany(m_fs->e2fs_ncg, u32);
        if (m_fs->e2fs_ngdb == 0) {
                printf("ext2fs: invalid number of group descriptor blocks\n");
                return EINVAL;
        }

        if (m_fs->e2fs_bsize < EXT2_DINODE_SIZE(m_fs)) {
                printf("ext2fs: invalid inode size\n");
                return EINVAL;
        }
        m_fs->e2fs_ipb = m_fs->e2fs_bsize / EXT2_DINODE_SIZE(m_fs);

        m_fs->e2fs_itpg = fs->e2fs_ipg / m_fs->e2fs_ipb;

        /*
         * Revision-specific checks
         */
        if (fs->e2fs_rev > E2FS_REV0) {
                char buf[256];
                if (fs->e2fs_first_ino != EXT2_FIRSTINO) {
                        printf("ext2fs: unsupported first inode position\n");
                        return EINVAL;
                }
                u32 = fs->e2fs_features_incompat & ~EXT2F_INCOMPAT_SUPP;
                if (u32) {
                        snprintb(buf, sizeof(buf), EXT2F_INCOMPAT_BITS, u32);
                        printf("ext2fs: unsupported incompat features: %s\n",
                            buf);
#ifndef EXT2_IGNORE_INCOMPAT_FEATURES
                        return EINVAL;
#endif
                }
                u32 = fs->e2fs_features_rocompat & ~EXT2F_ROCOMPAT_SUPP;
                if (!ronly && u32) {
                        snprintb(buf, sizeof(buf), EXT2F_ROCOMPAT_BITS, u32);
                        printf("ext2fs: unsupported ro-incompat features: %s\n",
                            buf);
#ifndef EXT2_IGNORE_ROCOMPAT_FEATURES
                        return EROFS;
#endif
                }
                if (fs->e2fs_inode_size == 0 || !powerof2(fs->e2fs_inode_size) || fs->e2fs_inode_size > m_fs->e2fs_bsize) {
                        printf("ext2fs: bad inode size\n");
                        return EINVAL;
                }
        }

        return 0;
}