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[minix3.git] / sys / ufs / ffs / ffs_wapbl.c

/*      $NetBSD: ffs_wapbl.c,v 1.25 2013/10/25 11:35:55 martin Exp $    */

/*-
 * Copyright (c) 2003,2006,2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Wasabi Systems, Inc.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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>
__KERNEL_RCSID(0, "$NetBSD: ffs_wapbl.c,v 1.25 2013/10/25 11:35:55 martin Exp $");

#define WAPBL_INTERNAL

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/file.h>
#include <sys/disk.h>
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/kauth.h>
#include <sys/wapbl.h>

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

#include <ufs/ffs/fs.h>
#include <ufs/ffs/ffs_extern.h>

#undef  WAPBL_DEBUG
#ifdef WAPBL_DEBUG
int ffs_wapbl_debug = 1;
#define DPRINTF(fmt, args...)                                           \
do {                                                                    \
        if (ffs_wapbl_debug)                                            \
                printf("%s:%d "fmt, __func__ , __LINE__, ##args);       \
} while (/* CONSTCOND */0)
#else
#define DPRINTF(fmt, args...)                                           \
do {                                                                    \
        /* nothing */                                                   \
} while (/* CONSTCOND */0)
#endif

static int ffs_superblock_layout(struct fs *);
static int wapbl_log_position(struct mount *, struct fs *, struct vnode *,
    daddr_t *, size_t *, size_t *, uint64_t *);
static int wapbl_create_infs_log(struct mount *, struct fs *, struct vnode *,
    daddr_t *, size_t *, uint64_t *);
static void wapbl_find_log_start(struct mount *, struct vnode *, off_t,
    daddr_t *, daddr_t *, size_t *);
static int wapbl_remove_log(struct mount *);
static int wapbl_allocate_log_file(struct mount *, struct vnode *,
    daddr_t *, size_t *, uint64_t *);

/*
 * Return the super block layout format - UFS1 or UFS2.
 * WAPBL only works with UFS2 layout (which is still available
 * with FFSv1).
 *
 * XXX Should this be in ufs/ffs/fs.h?  Same style of check is
 * also used in ffs_alloc.c in a few places.
 */
static int
ffs_superblock_layout(struct fs *fs)
{
        if ((fs->fs_magic == FS_UFS1_MAGIC) &&
            ((fs->fs_old_flags & FS_FLAGS_UPDATED) == 0))
                return 1;
        else
                return 2;
}

/*
 * This function is invoked after a log is replayed to
 * disk to perform logical cleanup actions as described by
 * the log
 */
void
ffs_wapbl_replay_finish(struct mount *mp)
{
        struct wapbl_replay *wr = mp->mnt_wapbl_replay;
        int i;
        int error;

        if (!wr)
                return;

        KDASSERT((mp->mnt_flag & MNT_RDONLY) == 0);

        for (i = 0; i < wr->wr_inodescnt; i++) {
                struct vnode *vp;
                struct inode *ip;
                error = VFS_VGET(mp, wr->wr_inodes[i].wr_inumber, &vp);
                if (error) {
                        printf("ffs_wapbl_replay_finish: "
                            "unable to cleanup inode %" PRIu32 "\n",
                            wr->wr_inodes[i].wr_inumber);
                        continue;
                }
                ip = VTOI(vp);
                KDASSERT(wr->wr_inodes[i].wr_inumber == ip->i_number);
#ifdef WAPBL_DEBUG
                printf("ffs_wapbl_replay_finish: "
                    "cleaning inode %" PRIu64 " size=%" PRIu64 " mode=%o nlink=%d\n",
                    ip->i_number, ip->i_size, ip->i_mode, ip->i_nlink);
#endif
                KASSERT(ip->i_nlink == 0);

                /*
                 * The journal may have left partially allocated inodes in mode
                 * zero.  This may occur if a crash occurs betweeen the node
                 * allocation in ffs_nodeallocg and when the node is properly
                 * initialized in ufs_makeinode.  If so, just dallocate them.
                 */
                if (ip->i_mode == 0) {
                        UFS_WAPBL_BEGIN(mp);
                        ffs_vfree(vp, ip->i_number, wr->wr_inodes[i].wr_imode);
                        UFS_WAPBL_END(mp);
                }
                vput(vp);
        }
        wapbl_replay_stop(wr);
        wapbl_replay_free(wr);
        mp->mnt_wapbl_replay = NULL;
}

/* Callback for wapbl */
void
ffs_wapbl_sync_metadata(struct mount *mp, daddr_t *deallocblks,
    int *dealloclens, int dealloccnt)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct fs *fs = ump->um_fs;
        int i, error __diagused;

#ifdef WAPBL_DEBUG_INODES
        ufs_wapbl_verify_inodes(mp, "ffs_wapbl_sync_metadata");
#endif

        for (i = 0; i< dealloccnt; i++) {
                /*
                 * blkfree errors are unreported, might silently fail
                 * if it cannot read the cylinder group block
                 */
                ffs_blkfree(fs, ump->um_devvp,
                    FFS_DBTOFSB(fs, deallocblks[i]), dealloclens[i], -1);
        }

        fs->fs_fmod = 0;
        fs->fs_time = time_second;
        error = ffs_cgupdate(ump, 0);
        KASSERT(error == 0);
}

void
ffs_wapbl_abort_sync_metadata(struct mount *mp, daddr_t *deallocblks,
    int *dealloclens, int dealloccnt)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct fs *fs = ump->um_fs;
        int i;

        for (i = 0; i < dealloccnt; i++) {
                /*
                 * Since the above blkfree may have failed, this blkalloc might
                 * fail as well, so don't check its error.  Note that if the
                 * blkfree succeeded above, then this shouldn't fail because
                 * the buffer will be locked in the current transaction.
                 */
                ffs_blkalloc_ump(ump, FFS_DBTOFSB(fs, deallocblks[i]),
                    dealloclens[i]);
        }
}

static int
wapbl_remove_log(struct mount *mp)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct fs *fs = ump->um_fs;
        struct vnode *vp;
        struct inode *ip;
        ino_t log_ino;
        int error;

        /* If super block layout is too old to support WAPBL, return */
        if (ffs_superblock_layout(fs) < 2)
                return 0;

        /* If all the log locators are 0, just clean up */
        if (fs->fs_journallocs[0] == 0 &&
            fs->fs_journallocs[1] == 0 &&
            fs->fs_journallocs[2] == 0 &&
            fs->fs_journallocs[3] == 0) {
                DPRINTF("empty locators, just clear\n");
                goto done;
        }

        switch (fs->fs_journal_location) {
        case UFS_WAPBL_JOURNALLOC_NONE:
                /* nothing! */
                DPRINTF("no log\n");
                break;

        case UFS_WAPBL_JOURNALLOC_IN_FILESYSTEM:
                log_ino = fs->fs_journallocs[UFS_WAPBL_INFS_INO];
                DPRINTF("in-fs log, ino = %" PRId64 "\n",log_ino);

                /* if no existing log inode, just clear all fields and bail */
                if (log_ino == 0)
                        goto done;
                error = VFS_VGET(mp, log_ino, &vp);
                if (error != 0) {
                        printf("ffs_wapbl: vget failed %d\n",
                            error);
                        /* clear out log info on error */
                        goto done;
                }
                ip = VTOI(vp);
                KASSERT(log_ino == ip->i_number);
                if ((ip->i_flags & SF_LOG) == 0) {
                        printf("ffs_wapbl: try to clear non-log inode "
                            "%" PRId64 "\n", log_ino);
                        vput(vp);
                        /* clear out log info on error */
                        goto done;
                }

                /*
                 * remove the log inode by setting its link count back
                 * to zero and bail.
                 */
                ip->i_nlink = 0;
                DIP_ASSIGN(ip, nlink, 0);
                vput(vp);

        case UFS_WAPBL_JOURNALLOC_END_PARTITION:
                DPRINTF("end-of-partition log\n");
                /* no extra work required */
                break;

        default:
                printf("ffs_wapbl: unknown journal type %d\n",
                    fs->fs_journal_location);
                break;
        }


done:
        /* Clear out all previous knowledge of journal */
        fs->fs_journal_version = 0;
        fs->fs_journal_location = 0;
        fs->fs_journal_flags = 0;
        fs->fs_journallocs[0] = 0;
        fs->fs_journallocs[1] = 0;
        fs->fs_journallocs[2] = 0;
        fs->fs_journallocs[3] = 0;
        (void) ffs_sbupdate(ump, MNT_WAIT);

        return 0;
}

int
ffs_wapbl_start(struct mount *mp)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct fs *fs = ump->um_fs;
        struct vnode *devvp = ump->um_devvp;
        daddr_t off;
        size_t count;
        size_t blksize;
        uint64_t extradata;
        int error;

        if (mp->mnt_wapbl == NULL) {
                if (fs->fs_journal_flags & UFS_WAPBL_FLAGS_CLEAR_LOG) {
                        /* Clear out any existing journal file */
                        error = wapbl_remove_log(mp);
                        if (error != 0)
                                return error;
                }

                if (mp->mnt_flag & MNT_LOG) {
                        KDASSERT(fs->fs_ronly == 0);

                        /* WAPBL needs UFS2 format super block */
                        if (ffs_superblock_layout(fs) < 2) {
                                printf("%s fs superblock in old format, "
                                   "not journaling\n",
                                   VFSTOUFS(mp)->um_fs->fs_fsmnt);
                                mp->mnt_flag &= ~MNT_LOG;
                                return EINVAL;
                        }

                        error = wapbl_log_position(mp, fs, devvp, &off,
                            &count, &blksize, &extradata);
                        if (error)
                                return error;

                        error = wapbl_start(&mp->mnt_wapbl, mp, devvp, off,
                            count, blksize, mp->mnt_wapbl_replay,
                            ffs_wapbl_sync_metadata,
                            ffs_wapbl_abort_sync_metadata);
                        if (error)
                                return error;

                        mp->mnt_wapbl_op = &wapbl_ops;

#ifdef WAPBL_DEBUG
                        printf("%s: enabling logging\n", fs->fs_fsmnt);
#endif

                        if ((fs->fs_flags & FS_DOWAPBL) == 0) {
                                UFS_WAPBL_BEGIN(mp);
                                fs->fs_flags |= FS_DOWAPBL;
                                error = ffs_sbupdate(ump, MNT_WAIT);
                                if (error) {
                                        UFS_WAPBL_END(mp);
                                        ffs_wapbl_stop(mp, MNT_FORCE);
                                        return error;
                                }
                                UFS_WAPBL_END(mp);
                                error = wapbl_flush(mp->mnt_wapbl, 1);
                                if (error) {
                                        ffs_wapbl_stop(mp, MNT_FORCE);
                                        return error;
                                }
                        }
                } else if (fs->fs_flags & FS_DOWAPBL) {
                        fs->fs_fmod = 1;
                        fs->fs_flags &= ~FS_DOWAPBL;
                }
        }

        /*
         * It is recommended that you finish replay with logging enabled.
         * However, even if logging is not enabled, the remaining log
         * replay should be safely recoverable with an fsck, so perform
         * it anyway.
         */
        if ((fs->fs_ronly == 0) && mp->mnt_wapbl_replay) {
                int saveflag = mp->mnt_flag & MNT_RDONLY;
                /*
                 * Make sure MNT_RDONLY is not set so that the inode
                 * cleanup in ufs_inactive will actually do its work.
                 */
                mp->mnt_flag &= ~MNT_RDONLY;
                ffs_wapbl_replay_finish(mp);
                mp->mnt_flag |= saveflag;
                KASSERT(fs->fs_ronly == 0);
        }

        return 0;
}

int
ffs_wapbl_stop(struct mount *mp, int force)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct fs *fs = ump->um_fs;
        int error;

        if (mp->mnt_wapbl) {
                KDASSERT(fs->fs_ronly == 0);

                /*
                 * Make sure turning off FS_DOWAPBL is only removed
                 * as the only change in the final flush since otherwise
                 * a transaction may reorder writes.
                 */
                error = wapbl_flush(mp->mnt_wapbl, 1);
                if (error && !force)
                        return error;
                if (error && force)
                        goto forceout;
                error = UFS_WAPBL_BEGIN(mp);
                if (error && !force)
                        return error;
                if (error && force)
                        goto forceout;
                KASSERT(fs->fs_flags & FS_DOWAPBL);

                fs->fs_flags &= ~FS_DOWAPBL;
                error = ffs_sbupdate(ump, MNT_WAIT);
                KASSERT(error == 0);    /* XXX a bit drastic! */
                UFS_WAPBL_END(mp);
        forceout:
                error = wapbl_stop(mp->mnt_wapbl, force);
                if (error) {
                        KASSERT(!force);
                        fs->fs_flags |= FS_DOWAPBL;
                        return error;
                }
                fs->fs_flags &= ~FS_DOWAPBL; /* Repeat in case of forced error */
                mp->mnt_wapbl = NULL;

#ifdef WAPBL_DEBUG
                printf("%s: disabled logging\n", fs->fs_fsmnt);
#endif
        }

        return 0;
}

int
ffs_wapbl_replay_start(struct mount *mp, struct fs *fs, struct vnode *devvp)
{
        int error;
        daddr_t off;
        size_t count;
        size_t blksize;
        uint64_t extradata;

        /*
         * WAPBL needs UFS2 format super block, if we got here with a
         * UFS1 format super block something is amiss...
         */
        if (ffs_superblock_layout(fs) < 2)
                return EINVAL;

        error = wapbl_log_position(mp, fs, devvp, &off, &count, &blksize,
            &extradata);

        if (error)
                return error;

        error = wapbl_replay_start(&mp->mnt_wapbl_replay, devvp, off,
                count, blksize);
        if (error)
                return error;

        mp->mnt_wapbl_op = &wapbl_ops;

        return 0;
}

/*
 * If the superblock doesn't already have a recorded journal location
 * then we allocate the journal in one of two positions:
 *
 *  - At the end of the partition after the filesystem if there's
 *    enough space.  "Enough space" is defined as >= 1MB of journal
 *    per 1GB of filesystem or 64MB, whichever is smaller.
 *
 *  - Inside the filesystem.  We try to allocate a contiguous journal
 *    based on the total filesystem size - the target is 1MB of journal
 *    per 1GB of filesystem, up to a maximum journal size of 64MB.  As
 *    a worst case allowing for fragmentation, we'll allocate a journal
 *    1/4 of the desired size but never smaller than 1MB.
 *
 *    XXX In the future if we allow for non-contiguous journal files we
 *    can tighten the above restrictions.
 *
 * XXX
 * These seems like a lot of duplication both here and in some of
 * the userland tools (fsck_ffs, dumpfs, tunefs) with similar 
 * "switch (fs_journal_location)" constructs.  Can we centralise
 * this sort of code somehow/somewhere?
 */
static int
wapbl_log_position(struct mount *mp, struct fs *fs, struct vnode *devvp,
    daddr_t *startp, size_t *countp, size_t *blksizep, uint64_t *extradatap)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        daddr_t logstart, logend, desired_logsize;
        uint64_t numsecs;
        unsigned secsize;
        int error, location;

        if (fs->fs_journal_version == UFS_WAPBL_VERSION) {
                switch (fs->fs_journal_location) {
                case UFS_WAPBL_JOURNALLOC_END_PARTITION:
                        DPRINTF("found existing end-of-partition log\n");
                        *startp = fs->fs_journallocs[UFS_WAPBL_EPART_ADDR];
                        *countp = fs->fs_journallocs[UFS_WAPBL_EPART_COUNT];
                        *blksizep = fs->fs_journallocs[UFS_WAPBL_EPART_BLKSZ];
                        DPRINTF(" start = %" PRId64 ", size = %zu, "
                            "blksize = %zu\n", *startp, *countp, *blksizep);
                        return 0;

                case UFS_WAPBL_JOURNALLOC_IN_FILESYSTEM:
                        DPRINTF("found existing in-filesystem log\n");
                        *startp = fs->fs_journallocs[UFS_WAPBL_INFS_ADDR];
                        *countp = fs->fs_journallocs[UFS_WAPBL_INFS_COUNT];
                        *blksizep = fs->fs_journallocs[UFS_WAPBL_INFS_BLKSZ];
                        DPRINTF(" start = %" PRId64 ", size = %zu, "
                            "blksize = %zu\n", *startp, *countp, *blksizep);
                        return 0;

                default:
                        printf("ffs_wapbl: unknown journal type %d\n",
                            fs->fs_journal_location);
                        return EINVAL;
                }
        }

        desired_logsize =
            ffs_lfragtosize(fs, fs->fs_size) / UFS_WAPBL_JOURNAL_SCALE;
        DPRINTF("desired log size = %" PRId64 " kB\n", desired_logsize / 1024);
        desired_logsize = max(desired_logsize, UFS_WAPBL_MIN_JOURNAL_SIZE);
        desired_logsize = min(desired_logsize, UFS_WAPBL_MAX_JOURNAL_SIZE);
        DPRINTF("adjusted desired log size = %" PRId64 " kB\n",
            desired_logsize / 1024);

        /* Is there space after after filesystem on partition for log? */
        logstart = FFS_FSBTODB(fs, fs->fs_size);
        error = getdisksize(devvp, &numsecs, &secsize);
        if (error)
                return error;
        KDASSERT(secsize != 0);
        logend = btodb(numsecs * secsize);

        if (dbtob(logend - logstart) >= desired_logsize) {
                DPRINTF("enough space, use end-of-partition log\n");

                location = UFS_WAPBL_JOURNALLOC_END_PARTITION;
                *blksizep = secsize;

                *startp = logstart;
                *countp = (logend - logstart);
                *extradatap = 0;

                /* convert to physical block numbers */
                *startp = dbtob(*startp) / secsize;
                *countp = dbtob(*countp) / secsize;

                fs->fs_journallocs[UFS_WAPBL_EPART_ADDR] = *startp;
                fs->fs_journallocs[UFS_WAPBL_EPART_COUNT] = *countp;
                fs->fs_journallocs[UFS_WAPBL_EPART_BLKSZ] = *blksizep;
                fs->fs_journallocs[UFS_WAPBL_EPART_UNUSED] = *extradatap;
        } else {
                DPRINTF("end-of-partition has only %" PRId64 " free\n",
                    logend - logstart);

                location = UFS_WAPBL_JOURNALLOC_IN_FILESYSTEM;
                *blksizep = secsize;

                error = wapbl_create_infs_log(mp, fs, devvp,
                                  startp, countp, extradatap);
                ffs_sync(mp, MNT_WAIT, FSCRED);

                /* convert to physical block numbers */
                *startp = dbtob(*startp) / secsize;
                *countp = dbtob(*countp) / secsize;

                fs->fs_journallocs[UFS_WAPBL_INFS_ADDR] = *startp;
                fs->fs_journallocs[UFS_WAPBL_INFS_COUNT] = *countp;
                fs->fs_journallocs[UFS_WAPBL_INFS_BLKSZ] = *blksizep;
                fs->fs_journallocs[UFS_WAPBL_INFS_INO] = *extradatap;
        }

        if (error == 0) {
                /* update superblock with log location */
                fs->fs_journal_version = UFS_WAPBL_VERSION;
                fs->fs_journal_location = location;
                fs->fs_journal_flags = 0;

                error = ffs_sbupdate(ump, MNT_WAIT);
        }

        return error;
}

/*
 * Try to create a journal log inside the filesystem.
 */
static int
wapbl_create_infs_log(struct mount *mp, struct fs *fs, struct vnode *devvp,
    daddr_t *startp, size_t *countp, uint64_t *extradatap)
{
        struct vnode *vp, *rvp;
        struct inode *ip;
        int error;

        if ((error = VFS_ROOT(mp, &rvp)) != 0)
                return error;

        error = UFS_VALLOC(rvp, 0 | S_IFREG, NOCRED, &vp);
        if (mp->mnt_flag & MNT_UPDATE) {
                vput(rvp);
        } else {
                VOP_UNLOCK(rvp);
                vgone(rvp);
        }
        if (error != 0)
                return error;

        vp->v_type = VREG;
        ip = VTOI(vp);
        ip->i_flag |= IN_ACCESS | IN_CHANGE | IN_UPDATE;
        ip->i_mode = 0 | IFREG;
        DIP_ASSIGN(ip, mode, ip->i_mode);
        ip->i_flags = SF_LOG;
        DIP_ASSIGN(ip, flags, ip->i_flags);
        ip->i_nlink = 1;
        DIP_ASSIGN(ip, nlink, 1);
        ffs_update(vp, NULL, NULL, UPDATE_WAIT);

        if ((error = wapbl_allocate_log_file(mp, vp,
                         startp, countp, extradatap)) != 0) {
                /*
                 * If we couldn't allocate the space for the log file,
                 * remove the inode by setting its link count back to
                 * zero and bail.
                 */
                ip->i_nlink = 0;
                DIP_ASSIGN(ip, nlink, 0);
                VOP_UNLOCK(vp);
                vgone(vp);

                return error;
        }

        /*
         * Now that we have the place-holder inode for the journal,
         * we don't need the vnode ever again.
         */
        VOP_UNLOCK(vp);
        vgone(vp);

        return 0;
}

int
wapbl_allocate_log_file(struct mount *mp, struct vnode *vp,
    daddr_t *startp, size_t *countp, uint64_t *extradatap)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct fs *fs = ump->um_fs;
        daddr_t addr, indir_addr;
        off_t logsize;
        size_t size;
        int error;

        logsize = 0;
        /* check if there's a suggested log size */
        if (fs->fs_journal_flags & UFS_WAPBL_FLAGS_CREATE_LOG &&
            fs->fs_journal_location == UFS_WAPBL_JOURNALLOC_IN_FILESYSTEM)
                logsize = fs->fs_journallocs[UFS_WAPBL_INFS_COUNT];

        if (vp->v_size > 0) {
                printf("%s: file size (%" PRId64 ") non zero\n", __func__,
                    vp->v_size);
                return EEXIST;
        }
        wapbl_find_log_start(mp, vp, logsize, &addr, &indir_addr, &size);
        if (addr == 0) {
                printf("%s: log not allocated, largest extent is "
                    "%" PRId64 "MB\n", __func__,
                    ffs_lblktosize(fs, size) / (1024 * 1024));
                return ENOSPC;
        }

        logsize = ffs_lblktosize(fs, size);     /* final log size */

        VTOI(vp)->i_ffs_first_data_blk = addr;
        VTOI(vp)->i_ffs_first_indir_blk = indir_addr;

        error = GOP_ALLOC(vp, 0, logsize, B_CONTIG, FSCRED);
        if (error) {
                printf("%s: GOP_ALLOC error %d\n", __func__, error);
                return error;
        }

        *startp     = FFS_FSBTODB(fs, addr);
        *countp     = btodb(logsize);
        *extradatap = VTOI(vp)->i_number;

        return 0;
}

/*
 * Find a suitable location for the journal in the filesystem.
 *
 * Our strategy here is to look for a contiguous block of free space
 * at least "logfile" MB in size (plus room for any indirect blocks).
 * We start at the middle of the filesystem and check each cylinder
 * group working outwards.  If "logfile" MB is not available as a
 * single contigous chunk, then return the address and size of the
 * largest chunk found.
 *
 * XXX 
 * At what stage does the search fail?  Is if the largest space we could
 * find is less than a quarter the requested space reasonable?  If the
 * search fails entirely, return a block address if "0" it indicate this.
 */
static void
wapbl_find_log_start(struct mount *mp, struct vnode *vp, off_t logsize,
    daddr_t *addr, daddr_t *indir_addr, size_t *size)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct fs *fs = ump->um_fs;
        struct vnode *devvp = ump->um_devvp;
        struct cg *cgp;
        struct buf *bp;
        uint8_t *blksfree;
        daddr_t blkno, best_addr, start_addr;
        daddr_t desired_blks, min_desired_blks;
        daddr_t freeblks, best_blks;
        int bpcg, cg, error, fixedsize, indir_blks, n, s;
        const int needswap = UFS_FSNEEDSWAP(fs);

        if (logsize == 0) {
                fixedsize = 0;  /* We can adjust the size if tight */
                logsize = ffs_lfragtosize(fs, fs->fs_dsize) /
                    UFS_WAPBL_JOURNAL_SCALE;
                DPRINTF("suggested log size = %" PRId64 "\n", logsize);
                logsize = max(logsize, UFS_WAPBL_MIN_JOURNAL_SIZE);
                logsize = min(logsize, UFS_WAPBL_MAX_JOURNAL_SIZE);
                DPRINTF("adjusted log size = %" PRId64 "\n", logsize);
        } else {
                fixedsize = 1;
                DPRINTF("fixed log size = %" PRId64 "\n", logsize);
        }

        desired_blks = logsize / fs->fs_bsize;
        DPRINTF("desired blocks = %" PRId64 "\n", desired_blks);

        /* add in number of indirect blocks needed */
        indir_blks = 0;
        if (desired_blks >= UFS_NDADDR) {
                struct indir indirs[UFS_NIADDR + 2];
                int num;

                error = ufs_getlbns(vp, desired_blks, indirs, &num);
                if (error) {
                        printf("%s: ufs_getlbns failed, error %d!\n",
                            __func__, error);
                        goto bad;
                }

                switch (num) {
                case 2:
                        indir_blks = 1;         /* 1st level indirect */
                        break;
                case 3:
                        indir_blks = 1 +        /* 1st level indirect */
                            1 +                 /* 2nd level indirect */
                            indirs[1].in_off + 1; /* extra 1st level indirect */
                        break;
                default:
                        printf("%s: unexpected numlevels %d from ufs_getlbns\n",
                            __func__, num);
                        *size = 0;
                        goto bad;
                }
                desired_blks += indir_blks;
        }
        DPRINTF("desired blocks = %" PRId64 " (including indirect)\n",
            desired_blks);

        /*
         * If a specific size wasn't requested, allow for a smaller log
         * if we're really tight for space...
         */
        min_desired_blks = desired_blks;
        if (!fixedsize)
                min_desired_blks = desired_blks / 4;

        /* Look at number of blocks per CG.  If it's too small, bail early. */
        bpcg = ffs_fragstoblks(fs, fs->fs_fpg);
        if (min_desired_blks > bpcg) {
                printf("ffs_wapbl: cylinder group size of %" PRId64 " MB "
                    " is not big enough for journal\n",
                    ffs_lblktosize(fs, bpcg) / (1024 * 1024));
                goto bad;
        }

        /*
         * Start with the middle cylinder group, and search outwards in
         * both directions until we either find the requested log size
         * or reach the start/end of the file system.  If we reach the
         * start/end without finding enough space for the full requested
         * log size, use the largest extent found if it is large enough
         * to satisfy the our minimum size.
         *
         * XXX
         * Can we just use the cluster contigsum stuff (esp on UFS2)
         * here to simplify this search code?
         */
        best_addr = 0;
        best_blks = 0;
        for (cg = fs->fs_ncg / 2, s = 0, n = 1;
            best_blks < desired_blks && cg >= 0 && cg < fs->fs_ncg;
            s++, n = -n, cg += n * s) {
                DPRINTF("check cg %d of %d\n", cg, fs->fs_ncg);
                error = bread(devvp, FFS_FSBTODB(fs, cgtod(fs, cg)),
                    fs->fs_cgsize, FSCRED, 0, &bp);
                if (error) {
                        continue;
                }
                cgp = (struct cg *)bp->b_data;
                if (!cg_chkmagic(cgp, UFS_FSNEEDSWAP(fs))) {
                        brelse(bp, 0);
                        continue;
                }

                blksfree = cg_blksfree(cgp, needswap);

                for (blkno = 0; blkno < bpcg;) {
                        /* look for next free block */
                        /* XXX use scanc() and fragtbl[] here? */
                        for (; blkno < bpcg - min_desired_blks; blkno++)
                                if (ffs_isblock(fs, blksfree, blkno))
                                        break;

                        /* past end of search space in this CG? */
                        if (blkno >= bpcg - min_desired_blks)
                                break;

                        /* count how many free blocks in this extent */
                        start_addr = blkno;
                        for (freeblks = 0; blkno < bpcg; blkno++, freeblks++)
                                if (!ffs_isblock(fs, blksfree, blkno))
                                        break;

                        if (freeblks > best_blks) {
                                best_blks = freeblks;
                                best_addr = ffs_blkstofrags(fs, start_addr) +
                                    cgbase(fs, cg);

                                if (freeblks >= desired_blks) {
                                        DPRINTF("found len %" PRId64
                                            " at offset %" PRId64 " in gc\n",
                                            freeblks, start_addr);
                                        break;
                                }
                        }
                }
                brelse(bp, 0);
        }
        DPRINTF("best found len = %" PRId64 ", wanted %" PRId64
            " at addr %" PRId64 "\n", best_blks, desired_blks, best_addr);

        if (best_blks < min_desired_blks) {
                *addr = 0;
                *indir_addr = 0;
        } else {
                /* put indirect blocks at start, and data blocks after */
                *addr = best_addr + ffs_blkstofrags(fs, indir_blks);
                *indir_addr = best_addr;
        }
        *size = min(desired_blks, best_blks) - indir_blks;
        return;

bad:
        *addr = 0;
        *indir_addr = 0;
        *size = 0;
        return;
}