/*      $NetBSD: ffs_alloc.c,v 1.174 2025/06/27 19:55:38 andvar Exp $   */

/*-
 * Copyright (c) 2008, 2009 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.
 */

/*
 * Copyright (c) 2002 Networks Associates Technology, Inc.
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by Marshall
 * Kirk McKusick and Network Associates Laboratories, the Security
 * Research Division of Network Associates, Inc. under DARPA/SPAWAR
 * contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
 * research program
 *
 * Copyright (c) 1982, 1986, 1989, 1993
 *      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_alloc.c 8.19 (Berkeley) 7/13/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ffs_alloc.c,v 1.174 2025/06/27 19:55:38 andvar Exp $");

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/cprng.h>
#include <sys/kauth.h>
#include <sys/kernel.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/syslog.h>
#include <sys/vnode.h>
#include <sys/wapbl.h>
#include <sys/cprng.h>

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

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

#ifdef UVM_PAGE_TRKOWN
#include <uvm/uvm_object.h>
#include <uvm/uvm_page.h>
#endif

static daddr_t ffs_alloccg(struct inode *, u_int, daddr_t, int, int, int);
static daddr_t ffs_alloccgblk(struct inode *, struct buf *, daddr_t, int, int);
static ino_t ffs_dirpref(struct inode *);
static daddr_t ffs_fragextend(struct inode *, u_int, daddr_t, int, int);
static void ffs_fserr(struct fs *, kauth_cred_t, const char *);
static daddr_t ffs_hashalloc(struct inode *, u_int, daddr_t, int, int, int,
    daddr_t (*)(struct inode *, u_int, daddr_t, int, int, int));
static daddr_t ffs_nodealloccg(struct inode *, u_int, daddr_t, int, int, int);
static int32_t ffs_mapsearch(struct fs *, struct cg *,
                                      daddr_t, int);
static void ffs_blkfree_common(struct ufsmount *, struct fs *, dev_t, struct buf *,
    daddr_t, long, bool);
static void ffs_freefile_common(struct ufsmount *, struct fs *, dev_t, struct buf *, ino_t,
    int, bool);

/* if 1, changes in optimalization strategy are logged */
int ffs_log_changeopt = 0;

/* in ffs_tables.c */
extern const int inside[], around[];
extern const u_char * const fragtbl[];

/* Basic consistency check for block allocations */
static int
ffs_check_bad_allocation(const char *func, struct fs *fs, daddr_t bno,
    long size, dev_t dev, ino_t inum)
{
        if ((u_int)size > fs->fs_bsize || ffs_fragoff(fs, size) != 0 ||
            ffs_fragnum(fs, bno) + ffs_numfrags(fs, size) > fs->fs_frag) {
                panic("%s: bad size: dev = 0x%llx, bno = %" PRId64 
                    " bsize = %d, size = %ld, fs = %s", func,
                    (long long)dev, bno, fs->fs_bsize, size, fs->fs_fsmnt);
        }

        if (bno >= fs->fs_size) {
                printf("%s: bad block %" PRId64 ", ino %llu\n", func, bno,
                    (unsigned long long)inum);
                ffs_fserr(fs, NOCRED, "bad block");
                return EINVAL;
        }
        return 0;
}

/*
 * Allocate a block in the file system.
 *
 * The size of the requested block is given, which must be some
 * multiple of fs_fsize and <= fs_bsize.
 * A preference may be optionally specified. If a preference is given
 * the following hierarchy is used to allocate a block:
 *   1) allocate the requested block.
 *   2) allocate a rotationally optimal block in the same cylinder.
 *   3) allocate a block in the same cylinder group.
 *   4) quadratically rehash into other cylinder groups, until an
 *      available block is located.
 * If no block preference is given the following hierarchy is used
 * to allocate a block:
 *   1) allocate a block in the cylinder group that contains the
 *      inode for the file.
 *   2) quadratically rehash into other cylinder groups, until an
 *      available block is located.
 *
 * => called with um_lock held
 * => releases um_lock before returning
 */
int
ffs_alloc(struct inode *ip, daddr_t lbn, daddr_t bpref, int size,
    int flags, kauth_cred_t cred, daddr_t *bnp)
{
        struct ufsmount *ump;
        struct fs *fs;
        daddr_t bno;
        u_int cg;
#if defined(QUOTA) || defined(QUOTA2)
        int error;
#endif

        fs = ip->i_fs;
        ump = ip->i_ump;

        KASSERT(mutex_owned(&ump->um_lock));

#ifdef UVM_PAGE_TRKOWN

        /*
         * Sanity-check that allocations within the file size
         * do not allow other threads to read the stale contents
         * of newly allocated blocks.
         * Usually pages will exist to cover the new allocation.
         * There is an optimization in ffs_write() where we skip
         * creating pages if several conditions are met:
         *  - the file must not be mapped (in any user address space).
         *  - the write must cover whole pages and whole blocks.
         * If those conditions are not met then pages must exist and
         * be locked by the current thread.
         */

        struct vnode *vp = ITOV(ip);
        if (vp->v_type == VREG && (flags & IO_EXT) == 0 &&
            ffs_lblktosize(fs, (voff_t)lbn) < round_page(vp->v_size) &&
            ((vp->v_vflag & VV_MAPPED) != 0 || (size & PAGE_MASK) != 0 ||
             ffs_blkoff(fs, size) != 0)) {
                struct vm_page *pg __diagused;
                struct uvm_object *uobj = &vp->v_uobj;
                voff_t off = trunc_page(ffs_lblktosize(fs, lbn));
                voff_t endoff = round_page(ffs_lblktosize(fs, lbn) + size);

                rw_enter(uobj->vmobjlock, RW_WRITER);
                while (off < endoff) {
                        pg = uvm_pagelookup(uobj, off);
                        KASSERT((pg != NULL && pg->owner_tag != NULL &&
                                 pg->owner == curproc->p_pid &&
                                 pg->lowner == curlwp->l_lid));
                        off += PAGE_SIZE;
                }
                rw_exit(uobj->vmobjlock);
        }
#endif

        *bnp = 0;

        KASSERTMSG((cred != NOCRED), "missing credential");
        KASSERTMSG(((u_int)size <= fs->fs_bsize),
            "bad size: dev = 0x%llx, bsize = %d, size = %d, fs = %s",
            (unsigned long long)ip->i_dev, fs->fs_bsize, size, fs->fs_fsmnt);
        KASSERTMSG((ffs_fragoff(fs, size) == 0),
            "bad size: dev = 0x%llx, bsize = %d, size = %d, fs = %s",
            (unsigned long long)ip->i_dev, fs->fs_bsize, size, fs->fs_fsmnt);

        if (size == fs->fs_bsize && fs->fs_cstotal.cs_nbfree == 0)
                goto nospace;
        if (freespace(fs, fs->fs_minfree) <= 0 &&
            kauth_authorize_system(cred, KAUTH_SYSTEM_FS_RESERVEDSPACE, 0, NULL,
            NULL, NULL) != 0)
                goto nospace;
#if defined(QUOTA) || defined(QUOTA2)
        mutex_exit(&ump->um_lock);
        if ((error = chkdq(ip, btodb(size), cred, 0)) != 0)
                return (error);
        mutex_enter(&ump->um_lock);
#endif

        if (bpref >= fs->fs_size)
                bpref = 0;
        if (bpref == 0)
                cg = ino_to_cg(fs, ip->i_number);
        else
                cg = dtog(fs, bpref);
        bno = ffs_hashalloc(ip, cg, bpref, size, 0, flags, ffs_alloccg);
        if (bno > 0) {
                DIP_ADD(ip, blocks, btodb(size));
                if (flags & IO_EXT)
                        ip->i_flag |= IN_CHANGE;
                else
                        ip->i_flag |= IN_CHANGE | IN_UPDATE;
                *bnp = bno;
                return (0);
        }
#if defined(QUOTA) || defined(QUOTA2)
        /*
         * Restore user's disk quota because allocation failed.
         */
        (void) chkdq(ip, -btodb(size), cred, FORCE);
#endif
        if (flags & B_CONTIG) {
                /*
                 * XXX ump->um_lock handling is "suspect" at best.
                 * For the case where ffs_hashalloc() fails early
                 * in the B_CONTIG case we reach here with um_lock
                 * already unlocked, so we can't release it again
                 * like in the normal error path.  See kern/39206.
                 *
                 *
                 * Fail silently - it's up to our caller to report
                 * errors.
                 */
                return (ENOSPC);
        }
nospace:
        mutex_exit(&ump->um_lock);
        ffs_fserr(fs, cred, "file system full");
        uprintf("\n%s: write failed, file system is full\n", fs->fs_fsmnt);
        return (ENOSPC);
}

/*
 * Reallocate a fragment to a bigger size
 *
 * The number and size of the old block is given, and a preference
 * and new size is also specified. The allocator attempts to extend
 * the original block. Failing that, the regular block allocator is
 * invoked to get an appropriate block.
 *
 * => called with um_lock held
 * => return with um_lock released
 */
int
ffs_realloccg(struct inode *ip, daddr_t lbprev, daddr_t bprev, daddr_t bpref,
    int osize, int nsize, int flags, kauth_cred_t cred, struct buf **bpp,
    daddr_t *blknop)
{
        struct ufsmount *ump;
        struct fs *fs;
        struct buf *bp;
        u_int cg, request;
        int error;
        daddr_t bno;

        fs = ip->i_fs;
        ump = ip->i_ump;

        KASSERT(mutex_owned(&ump->um_lock));

#ifdef UVM_PAGE_TRKOWN

        /*
         * Sanity-check that allocations within the file size
         * do not allow other threads to read the stale contents
         * of newly allocated blocks.
         * Unlike in ffs_alloc(), here pages must always exist
         * for such allocations, because only the last block of a file
         * can be a fragment and ffs_write() will reallocate the
         * fragment to the new size using ufs_balloc_range(),
         * which always creates pages to cover blocks it allocates.
         */

        if (ITOV(ip)->v_type == VREG) {
                struct vm_page *pg __diagused;
                struct uvm_object *uobj = &ITOV(ip)->v_uobj;
                voff_t off = trunc_page(ffs_lblktosize(fs, lbprev));
                voff_t endoff = round_page(ffs_lblktosize(fs, lbprev) + osize);

                rw_enter(uobj->vmobjlock, RW_WRITER);
                while (off < endoff) {
                        pg = uvm_pagelookup(uobj, off);
                        KASSERT(pg->owner == curproc->p_pid &&
                                pg->lowner == curlwp->l_lid);
                        off += PAGE_SIZE;
                }
                rw_exit(uobj->vmobjlock);
        }
#endif

        KASSERTMSG((cred != NOCRED), "missing credential");
        KASSERTMSG(((u_int)osize <= fs->fs_bsize),
            "bad size: dev=0x%llx, bsize=%d, osize=%d, nsize=%d, fs=%s",
            (unsigned long long)ip->i_dev, fs->fs_bsize, osize, nsize,
            fs->fs_fsmnt);
        KASSERTMSG((ffs_fragoff(fs, osize) == 0),
            "bad size: dev=0x%llx, bsize=%d, osize=%d, nsize=%d, fs=%s",
            (unsigned long long)ip->i_dev, fs->fs_bsize, osize, nsize,
            fs->fs_fsmnt);
        KASSERTMSG(((u_int)nsize <= fs->fs_bsize),
            "bad size: dev=0x%llx, bsize=%d, osize=%d, nsize=%d, fs=%s",
            (unsigned long long)ip->i_dev, fs->fs_bsize, osize, nsize,
            fs->fs_fsmnt);
        KASSERTMSG((ffs_fragoff(fs, nsize) == 0),
            "bad size: dev=0x%llx, bsize=%d, osize=%d, nsize=%d, fs=%s",
            (unsigned long long)ip->i_dev, fs->fs_bsize, osize, nsize,
            fs->fs_fsmnt);

        if (freespace(fs, fs->fs_minfree) <= 0 &&
            kauth_authorize_system(cred, KAUTH_SYSTEM_FS_RESERVEDSPACE, 0, NULL,
            NULL, NULL) != 0) {
                mutex_exit(&ump->um_lock);
                goto nospace;
        }

        if (bprev == 0) {
                panic("%s: bad bprev: dev = 0x%llx, bsize = %d, bprev = %"
                    PRId64 ", fs = %s", __func__,
                    (unsigned long long)ip->i_dev, fs->fs_bsize, bprev,
                    fs->fs_fsmnt);
        }
        mutex_exit(&ump->um_lock);

        /*
         * Allocate the extra space in the buffer.
         */
        if (bpp != NULL &&
            (error = bread(ITOV(ip), lbprev, osize, 0, &bp)) != 0) {
                return (error);
        }
#if defined(QUOTA) || defined(QUOTA2)
        if ((error = chkdq(ip, btodb(nsize - osize), cred, 0)) != 0) {
                if (bpp != NULL) {
                        brelse(bp, 0);
                }
                return (error);
        }
#endif
        /*
         * Check for extension in the existing location.
         */
        cg = dtog(fs, bprev);
        mutex_enter(&ump->um_lock);
        if ((bno = ffs_fragextend(ip, cg, bprev, osize, nsize)) != 0) {
                DIP_ADD(ip, blocks, btodb(nsize - osize));
                if (flags & IO_EXT)
                        ip->i_flag |= IN_CHANGE;
                else
                        ip->i_flag |= IN_CHANGE | IN_UPDATE;

                if (bpp != NULL) {
                        if (bp->b_blkno != FFS_FSBTODB(fs, bno)) {
                                panic("%s: bad blockno %#llx != %#llx",
                                    __func__, (unsigned long long) bp->b_blkno,
                                    (unsigned long long)FFS_FSBTODB(fs, bno));
                        }
                        allocbuf(bp, nsize, 1);
                        memset((char *)bp->b_data + osize, 0, nsize - osize);
                        mutex_enter(bp->b_objlock);
                        KASSERT(!cv_has_waiters(&bp->b_done));
                        bp->b_oflags |= BO_DONE;
                        mutex_exit(bp->b_objlock);
                        *bpp = bp;
                }
                if (blknop != NULL) {
                        *blknop = bno;
                }
                return (0);
        }
        /*
         * Allocate a new disk location.
         */
        if (bpref >= fs->fs_size)
                bpref = 0;
        switch ((int)fs->fs_optim) {
        case FS_OPTSPACE:
                /*
                 * Allocate an exact sized fragment. Although this makes
                 * best use of space, we will waste time relocating it if
                 * the file continues to grow. If the fragmentation is
                 * less than half of the minimum free reserve, we choose
                 * to begin optimizing for time.
                 */
                request = nsize;
                if (fs->fs_minfree < 5 ||
                    fs->fs_cstotal.cs_nffree >
                    fs->fs_dsize * fs->fs_minfree / (2 * 100))
                        break;

                if (ffs_log_changeopt) {
                        log(LOG_NOTICE,
                                "%s: optimization changed from SPACE to TIME\n",
                                fs->fs_fsmnt);
                }

                fs->fs_optim = FS_OPTTIME;
                break;
        case FS_OPTTIME:
                /*
                 * At this point we have discovered a file that is trying to
                 * grow a small fragment to a larger fragment. To save time,
                 * we allocate a full sized block, then free the unused portion.
                 * If the file continues to grow, the `ffs_fragextend' call
                 * above will be able to grow it in place without further
                 * copying. If aberrant programs cause disk fragmentation to
                 * grow within 2% of the free reserve, we choose to begin
                 * optimizing for space.
                 */
                request = fs->fs_bsize;
                if (fs->fs_cstotal.cs_nffree <
                    fs->fs_dsize * (fs->fs_minfree - 2) / 100)
                        break;

                if (ffs_log_changeopt) {
                        log(LOG_NOTICE,
                                "%s: optimization changed from TIME to SPACE\n",
                                fs->fs_fsmnt);
                }

                fs->fs_optim = FS_OPTSPACE;
                break;
        default:
                panic("%s: bad optim: dev = 0x%llx, optim = %d, fs = %s",
                    __func__, (unsigned long long)ip->i_dev, fs->fs_optim,
                    fs->fs_fsmnt);
                /* NOTREACHED */
        }
        bno = ffs_hashalloc(ip, cg, bpref, request, nsize, 0, ffs_alloccg);
        if (bno > 0) {
                /*
                 * Use forced deallocation registration, we can't handle
                 * failure here. This is safe, as this place is ever hit
                 * maximum once per write operation, when fragment is extended
                 * to longer fragment, or a full block.
                 */
                if ((ip->i_ump->um_mountp->mnt_wapbl) &&
                    (ITOV(ip)->v_type != VREG)) {
                        /* this should never fail */
                        error = UFS_WAPBL_REGISTER_DEALLOCATION_FORCE(
                            ip->i_ump->um_mountp, FFS_FSBTODB(fs, bprev),
                            osize);
                        if (error)
                                panic("ffs_realloccg: dealloc registration failed");
                } else {
                        ffs_blkfree(fs, ip->i_devvp, bprev, (long)osize,
                            ip->i_number);
                }
                DIP_ADD(ip, blocks, btodb(nsize - osize));
                if (flags & IO_EXT)
                        ip->i_flag |= IN_CHANGE;
                else
                        ip->i_flag |= IN_CHANGE | IN_UPDATE;
                if (bpp != NULL) {
                        bp->b_blkno = FFS_FSBTODB(fs, bno);
                        allocbuf(bp, nsize, 1);
                        memset((char *)bp->b_data + osize, 0, (u_int)nsize - osize);
                        mutex_enter(bp->b_objlock);
                        KASSERT(!cv_has_waiters(&bp->b_done));
                        bp->b_oflags |= BO_DONE;
                        mutex_exit(bp->b_objlock);
                        *bpp = bp;
                }
                if (blknop != NULL) {
                        *blknop = bno;
                }
                return (0);
        }
        mutex_exit(&ump->um_lock);

#if defined(QUOTA) || defined(QUOTA2)
        /*
         * Restore user's disk quota because allocation failed.
         */
        (void) chkdq(ip, -btodb(nsize - osize), cred, FORCE);
#endif
        if (bpp != NULL) {
                brelse(bp, 0);
        }

nospace:
        /*
         * no space available
         */
        ffs_fserr(fs, cred, "file system full");
        uprintf("\n%s: write failed, file system is full\n", fs->fs_fsmnt);
        return (ENOSPC);
}

/*
 * Allocate an inode in the file system.
 *
 * If allocating a directory, use ffs_dirpref to select the inode.
 * If allocating in a directory, the following hierarchy is followed:
 *   1) allocate the preferred inode.
 *   2) allocate an inode in the same cylinder group.
 *   3) quadratically rehash into other cylinder groups, until an
 *      available inode is located.
 * If no inode preference is given the following hierarchy is used
 * to allocate an inode:
 *   1) allocate an inode in cylinder group 0.
 *   2) quadratically rehash into other cylinder groups, until an
 *      available inode is located.
 *
 * => um_lock not held upon entry or return
 */
int
ffs_valloc(struct vnode *pvp, int mode, kauth_cred_t cred, ino_t *inop)
{
        struct ufsmount *ump;
        struct inode *pip;
        struct fs *fs;
        ino_t ino, ipref;
        u_int cg;
        int error;

        UFS_WAPBL_JUNLOCK_ASSERT(pvp->v_mount);

        pip = VTOI(pvp);
        fs = pip->i_fs;
        ump = pip->i_ump;

        error = UFS_WAPBL_BEGIN(pvp->v_mount);
        if (error) {
                return error;
        }
        mutex_enter(&ump->um_lock);
        if (fs->fs_cstotal.cs_nifree == 0)
                goto noinodes;

        if ((mode & IFMT) == IFDIR)
                ipref = ffs_dirpref(pip);
        else
                ipref = pip->i_number;
        if (ipref >= fs->fs_ncg * fs->fs_ipg)
                ipref = 0;
        cg = ino_to_cg(fs, ipref);
        /*
         * Track number of dirs created one after another
         * in a same cg without intervening by files.
         */
        if ((mode & IFMT) == IFDIR) {
                if (fs->fs_contigdirs[cg] < 255)
                        fs->fs_contigdirs[cg]++;
        } else {
                if (fs->fs_contigdirs[cg] > 0)
                        fs->fs_contigdirs[cg]--;
        }
        ino = (ino_t)ffs_hashalloc(pip, cg, ipref, mode, 0, 0, ffs_nodealloccg);
        if (ino == 0)
                goto noinodes;
        UFS_WAPBL_END(pvp->v_mount);
        *inop = ino;
        return 0;

noinodes:
        mutex_exit(&ump->um_lock);
        UFS_WAPBL_END(pvp->v_mount);
        ffs_fserr(fs, cred, "out of inodes");
        uprintf("\n%s: create/symlink failed, no inodes free\n", fs->fs_fsmnt);
        return ENOSPC;
}

/*
 * Find a cylinder group in which to place a directory.
 *
 * The policy implemented by this algorithm is to allocate a
 * directory inode in the same cylinder group as its parent
 * directory, but also to reserve space for its files inodes
 * and data. Restrict the number of directories which may be
 * allocated one after another in the same cylinder group
 * without intervening allocation of files.
 *
 * If we allocate a first level directory then force allocation
 * in another cylinder group.
 */
static ino_t
ffs_dirpref(struct inode *pip)
{
        register struct fs *fs;
        u_int cg, prefcg;
        uint64_t dirsize, cgsize, curdsz;
        u_int avgifree, avgbfree, avgndir;
        u_int minifree, minbfree, maxndir;
        u_int mincg, minndir;
        u_int maxcontigdirs;

        KASSERT(mutex_owned(&pip->i_ump->um_lock));

        fs = pip->i_fs;

        avgifree = fs->fs_cstotal.cs_nifree / fs->fs_ncg;
        avgbfree = fs->fs_cstotal.cs_nbfree / fs->fs_ncg;
        avgndir = fs->fs_cstotal.cs_ndir / fs->fs_ncg;

        /*
         * Force allocation in another cg if creating a first level dir.
         */
        if (ITOV(pip)->v_vflag & VV_ROOT) {
                prefcg = cprng_fast32() % fs->fs_ncg;
                mincg = prefcg;
                minndir = fs->fs_ipg;
                for (cg = prefcg; cg < fs->fs_ncg; cg++)
                        if (fs->fs_cs(fs, cg).cs_ndir < minndir &&
                            fs->fs_cs(fs, cg).cs_nifree >= avgifree &&
                            fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                                mincg = cg;
                                minndir = fs->fs_cs(fs, cg).cs_ndir;
                        }
                for (cg = 0; cg < prefcg; cg++)
                        if (fs->fs_cs(fs, cg).cs_ndir < minndir &&
                            fs->fs_cs(fs, cg).cs_nifree >= avgifree &&
                            fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                                mincg = cg;
                                minndir = fs->fs_cs(fs, cg).cs_ndir;
                        }
                return ((ino_t)(fs->fs_ipg * mincg));
        }

        /*
         * Count various limits which used for
         * optimal allocation of a directory inode.
         * Try cylinder groups with >75% avgifree and avgbfree.
         * Avoid cylinder groups with no free blocks or inodes as that
         * triggers an I/O-expensive cylinder group scan.
         */
        maxndir = uimin(avgndir + fs->fs_ipg / 16, fs->fs_ipg);
        minifree = avgifree - avgifree / 4;
        if (minifree < 1)
                minifree = 1;
        minbfree = avgbfree - avgbfree / 4;
        if (minbfree < 1)
                minbfree = 1;
        cgsize = (int64_t)fs->fs_fsize * fs->fs_fpg;
        dirsize = (int64_t)fs->fs_avgfilesize * fs->fs_avgfpdir;
        if (avgndir != 0) {
                curdsz = (cgsize - (int64_t)avgbfree * fs->fs_bsize) / avgndir;
                if (dirsize < curdsz)
                        dirsize = curdsz;
        }
        if (cgsize < dirsize * 255)
                maxcontigdirs = (avgbfree * fs->fs_bsize) / dirsize;
        else
                maxcontigdirs = 255;
        if (fs->fs_avgfpdir > 0)
                maxcontigdirs = uimin(maxcontigdirs,
                                    fs->fs_ipg / fs->fs_avgfpdir);
        if (maxcontigdirs == 0)
                maxcontigdirs = 1;

        /*
         * Limit number of dirs in one cg and reserve space for
         * regular files, but only if we have no deficit in
         * inodes or space.
         */
        prefcg = ino_to_cg(fs, pip->i_number);
        for (cg = prefcg; cg < fs->fs_ncg; cg++)
                if (fs->fs_cs(fs, cg).cs_ndir < maxndir &&
                    fs->fs_cs(fs, cg).cs_nifree >= minifree &&
                    fs->fs_cs(fs, cg).cs_nbfree >= minbfree) {
                        if (fs->fs_contigdirs[cg] < maxcontigdirs)
                                return ((ino_t)(fs->fs_ipg * cg));
                }
        for (cg = 0; cg < prefcg; cg++)
                if (fs->fs_cs(fs, cg).cs_ndir < maxndir &&
                    fs->fs_cs(fs, cg).cs_nifree >= minifree &&
                    fs->fs_cs(fs, cg).cs_nbfree >= minbfree) {
                        if (fs->fs_contigdirs[cg] < maxcontigdirs)
                                return ((ino_t)(fs->fs_ipg * cg));
                }
        /*
         * This is a backstop when we are deficient in space.
         */
        for (cg = prefcg; cg < fs->fs_ncg; cg++)
                if (fs->fs_cs(fs, cg).cs_nifree >= avgifree)
                        return ((ino_t)(fs->fs_ipg * cg));
        for (cg = 0; cg < prefcg; cg++)
                if (fs->fs_cs(fs, cg).cs_nifree >= avgifree)
                        break;
        return ((ino_t)(fs->fs_ipg * cg));
}

/*
 * Select the desired position for the next block in a file.  The file is
 * logically divided into sections. The first section is composed of the
 * direct blocks. Each additional section contains fs_maxbpg blocks.
 *
 * If no blocks have been allocated in the first section, the policy is to
 * request a block in the same cylinder group as the inode that describes
 * the file. If no blocks have been allocated in any other section, the
 * policy is to place the section in a cylinder group with a greater than
 * average number of free blocks.  An appropriate cylinder group is found
 * by using a rotor that sweeps the cylinder groups. When a new group of
 * blocks is needed, the sweep begins in the cylinder group following the
 * cylinder group from which the previous allocation was made. The sweep
 * continues until a cylinder group with greater than the average number
 * of free blocks is found. If the allocation is for the first block in an
 * indirect block, the information on the previous allocation is unavailable;
 * here a best guess is made based upon the logical block number being
 * allocated.
 *
 * If a section is already partially allocated, the policy is to
 * contiguously allocate fs_maxcontig blocks.  The end of one of these
 * contiguous blocks and the beginning of the next is laid out
 * contiguously if possible.
 *
 * => um_lock held on entry and exit
 */
daddr_t
ffs_blkpref_ufs1(struct inode *ip, daddr_t lbn, int indx, int flags,
    int32_t *bap /* XXX ondisk32 */)
{
        struct fs *fs;
        u_int cg;
        u_int avgbfree, startcg;

        KASSERT(mutex_owned(&ip->i_ump->um_lock));

        fs = ip->i_fs;

        /*
         * If allocating a contiguous file with B_CONTIG, use the hints
         * in the inode extensions to return the desired block.
         *
         * For metadata (indirect blocks) return the address of where
         * the first indirect block resides - we'll scan for the next
         * available slot if we need to allocate more than one indirect
         * block.  For data, return the address of the actual block
         * relative to the address of the first data block.
         */
        if (flags & B_CONTIG) {
                KASSERT(ip->i_ffs_first_data_blk != 0);
                KASSERT(ip->i_ffs_first_indir_blk != 0);
                if (flags & B_METAONLY)
                        return ip->i_ffs_first_indir_blk;
                else
                        return ip->i_ffs_first_data_blk + ffs_blkstofrags(fs, lbn);
        }

        if (indx % fs->fs_maxbpg == 0 || bap[indx - 1] == 0) {
                if (lbn < UFS_NDADDR + FFS_NINDIR(fs)) {
                        cg = ino_to_cg(fs, ip->i_number);
                        return (cgbase(fs, cg) + fs->fs_frag);
                }
                /*
                 * Find a cylinder with greater than average number of
                 * unused data blocks.
                 */
                if (indx == 0 || bap[indx - 1] == 0)
                        startcg =
                            ino_to_cg(fs, ip->i_number) + lbn / fs->fs_maxbpg;
                else
                        startcg = dtog(fs,
                                ufs_rw32(bap[indx - 1], UFS_FSNEEDSWAP(fs)) + 1);
                startcg %= fs->fs_ncg;
                avgbfree = fs->fs_cstotal.cs_nbfree / fs->fs_ncg;
                for (cg = startcg; cg < fs->fs_ncg; cg++)
                        if (fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                                return (cgbase(fs, cg) + fs->fs_frag);
                        }
                for (cg = 0; cg < startcg; cg++)
                        if (fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                                return (cgbase(fs, cg) + fs->fs_frag);
                        }
                return (0);
        }
        /*
         * We just always try to lay things out contiguously.
         */
        return ufs_rw32(bap[indx - 1], UFS_FSNEEDSWAP(fs)) + fs->fs_frag;
}

daddr_t
ffs_blkpref_ufs2(struct inode *ip, daddr_t lbn, int indx, int flags,
    int64_t *bap)
{
        struct fs *fs;
        u_int cg;
        u_int avgbfree, startcg;

        KASSERT(mutex_owned(&ip->i_ump->um_lock));

        fs = ip->i_fs;

        /*
         * If allocating a contiguous file with B_CONTIG, use the hints
         * in the inode extensions to return the desired block.
         *
         * For metadata (indirect blocks) return the address of where
         * the first indirect block resides - we'll scan for the next
         * available slot if we need to allocate more than one indirect
         * block.  For data, return the address of the actual block
         * relative to the address of the first data block.
         */
        if (flags & B_CONTIG) {
                KASSERT(ip->i_ffs_first_data_blk != 0);
                KASSERT(ip->i_ffs_first_indir_blk != 0);
                if (flags & B_METAONLY)
                        return ip->i_ffs_first_indir_blk;
                else
                        return ip->i_ffs_first_data_blk + ffs_blkstofrags(fs, lbn);
        }

        if (indx % fs->fs_maxbpg == 0 || bap[indx - 1] == 0) {
                if (lbn < UFS_NDADDR + FFS_NINDIR(fs)) {
                        cg = ino_to_cg(fs, ip->i_number);
                        return (cgbase(fs, cg) + fs->fs_frag);
                }
                /*
                 * Find a cylinder with greater than average number of
                 * unused data blocks.
                 */
                if (indx == 0 || bap[indx - 1] == 0)
                        startcg =
                            ino_to_cg(fs, ip->i_number) + lbn / fs->fs_maxbpg;
                else
                        startcg = dtog(fs,
                                ufs_rw64(bap[indx - 1], UFS_FSNEEDSWAP(fs)) + 1);
                startcg %= fs->fs_ncg;
                avgbfree = fs->fs_cstotal.cs_nbfree / fs->fs_ncg;
                for (cg = startcg; cg < fs->fs_ncg; cg++)
                        if (fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                                return (cgbase(fs, cg) + fs->fs_frag);
                        }
                for (cg = 0; cg < startcg; cg++)
                        if (fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                                return (cgbase(fs, cg) + fs->fs_frag);
                        }
                return (0);
        }
        /*
         * We just always try to lay things out contiguously.
         */
        return ufs_rw64(bap[indx - 1], UFS_FSNEEDSWAP(fs)) + fs->fs_frag;
}


/*
 * Implement the cylinder overflow algorithm.
 *
 * The policy implemented by this algorithm is:
 *   1) allocate the block in its requested cylinder group.
 *   2) quadratically rehash on the cylinder group number.
 *   3) brute force search for a free block.
 *
 * => called with um_lock held
 * => returns with um_lock released on success, held on failure
 *    (*allocator releases lock on success, retains lock on failure)
 */
/*VARARGS5*/
static daddr_t
ffs_hashalloc(struct inode *ip, u_int cg, daddr_t pref,
    int size /* size for data blocks, mode for inodes */,
    int realsize,
    int flags,
    daddr_t (*allocator)(struct inode *, u_int, daddr_t, int, int, int))
{
        struct fs *fs;
        daddr_t result;
        u_int i, icg = cg;

        fs = ip->i_fs;
        /*
         * 1: preferred cylinder group
         */
        result = (*allocator)(ip, cg, pref, size, realsize, flags);
        if (result)
                return (result);

        if (flags & B_CONTIG)
                return (result);
        /*
         * 2: quadratic rehash
         */
        for (i = 1; i < fs->fs_ncg; i *= 2) {
                cg += i;
                if (cg >= fs->fs_ncg)
                        cg -= fs->fs_ncg;
                result = (*allocator)(ip, cg, 0, size, realsize, flags);
                if (result)
                        return (result);
        }
        /*
         * 3: brute force search
         * Note that we start at i == 2, since 0 was checked initially,
         * and 1 is always checked in the quadratic rehash.
         */
        cg = (icg + 2) % fs->fs_ncg;
        for (i = 2; i < fs->fs_ncg; i++) {
                result = (*allocator)(ip, cg, 0, size, realsize, flags);
                if (result)
                        return (result);
                cg++;
                if (cg == fs->fs_ncg)
                        cg = 0;
        }
        return (0);
}

/*
 * Determine whether a fragment can be extended.
 *
 * Check to see if the necessary fragments are available, and
 * if they are, allocate them.
 *
 * => called with um_lock held
 * => returns with um_lock released on success, held on failure
 */
static daddr_t
ffs_fragextend(struct inode *ip, u_int cg, daddr_t bprev, int osize, int nsize)
{
        struct ufsmount *ump;
        struct fs *fs;
        struct cg *cgp;
        struct buf *bp;
        daddr_t bno;
        int frags, bbase;
        int i, error;
        u_int8_t *blksfree;

        fs = ip->i_fs;
        ump = ip->i_ump;

        KASSERT(mutex_owned(&ump->um_lock));

        if (fs->fs_cs(fs, cg).cs_nffree < ffs_numfrags(fs, nsize - osize))
                return (0);
        frags = ffs_numfrags(fs, nsize);
        bbase = ffs_fragnum(fs, bprev);
        if (bbase > ffs_fragnum(fs, (bprev + frags - 1))) {
                /* cannot extend across a block boundary */
                return (0);
        }
        mutex_exit(&ump->um_lock);
        error = bread(ip->i_devvp, FFS_FSBTODB(fs, cgtod(fs, cg)),
                (int)fs->fs_cgsize, B_MODIFY, &bp);
        if (error)
                goto fail;
        cgp = (struct cg *)bp->b_data;
        if (!cg_chkmagic(cgp, UFS_FSNEEDSWAP(fs)))
                goto fail;
        cgp->cg_old_time = ufs_rw32(time_second, UFS_FSNEEDSWAP(fs));
        if ((fs->fs_magic != FS_UFS1_MAGIC) ||
            (fs->fs_old_flags & FS_FLAGS_UPDATED))
                cgp->cg_time = ufs_rw64(time_second, UFS_FSNEEDSWAP(fs));
        bno = dtogd(fs, bprev);
        blksfree = cg_blksfree(cgp, UFS_FSNEEDSWAP(fs));
        for (i = ffs_numfrags(fs, osize); i < frags; i++)
                if (isclr(blksfree, bno + i))
                        goto fail;
        /*
         * the current fragment can be extended
         * deduct the count on fragment being extended into
         * increase the count on the remaining fragment (if any)
         * allocate the extended piece
         */
        for (i = frags; i < fs->fs_frag - bbase; i++)
                if (isclr(blksfree, bno + i))
                        break;
        ufs_add32(cgp->cg_frsum[i - ffs_numfrags(fs, osize)], -1, UFS_FSNEEDSWAP(fs));
        if (i != frags)
                ufs_add32(cgp->cg_frsum[i - frags], 1, UFS_FSNEEDSWAP(fs));
        mutex_enter(&ump->um_lock);
        for (i = ffs_numfrags(fs, osize); i < frags; i++) {
                clrbit(blksfree, bno + i);
                ufs_add32(cgp->cg_cs.cs_nffree, -1, UFS_FSNEEDSWAP(fs));
                fs->fs_cstotal.cs_nffree--;
                fs->fs_cs(fs, cg).cs_nffree--;
        }
        fs->fs_fmod = 1;
        ACTIVECG_CLR(fs, cg);
        mutex_exit(&ump->um_lock);
        bdwrite(bp);
        return (bprev);

 fail:
        if (bp != NULL)
                brelse(bp, 0);
        mutex_enter(&ump->um_lock);
        return (0);
}

/*
 * Determine whether a block can be allocated.
 *
 * Check to see if a block of the appropriate size is available,
 * and if it is, allocate it.
 */
static daddr_t
ffs_alloccg(struct inode *ip, u_int cg, daddr_t bpref, int size, int realsize,
    int flags)
{
        struct ufsmount *ump;
        struct fs *fs = ip->i_fs;
        struct cg *cgp;
        struct buf *bp;
        int32_t bno;
        daddr_t blkno;
        int error, frags, allocsiz, i;
        u_int8_t *blksfree;
        const int needswap = UFS_FSNEEDSWAP(fs);

        ump = ip->i_ump;

        KASSERT(mutex_owned(&ump->um_lock));

        if (fs->fs_cs(fs, cg).cs_nbfree == 0 && size == fs->fs_bsize)
                return (0);
        mutex_exit(&ump->um_lock);
        error = bread(ip->i_devvp, FFS_FSBTODB(fs, cgtod(fs, cg)),
                (int)fs->fs_cgsize, B_MODIFY, &bp);
        if (error)
                goto fail;
        cgp = (struct cg *)bp->b_data;
        if (!cg_chkmagic(cgp, needswap) ||
            (cgp->cg_cs.cs_nbfree == 0 && size == fs->fs_bsize))
                goto fail;
        cgp->cg_old_time = ufs_rw32(time_second, needswap);
        if ((fs->fs_magic != FS_UFS1_MAGIC) ||
            (fs->fs_old_flags & FS_FLAGS_UPDATED))
                cgp->cg_time = ufs_rw64(time_second, needswap);
        if (size == fs->fs_bsize) {
                mutex_enter(&ump->um_lock);
                blkno = ffs_alloccgblk(ip, bp, bpref, realsize, flags);
                ACTIVECG_CLR(fs, cg);
                mutex_exit(&ump->um_lock);

                /*
                 * If actually needed size is lower, free the extra blocks now.
                 * This is safe to call here, there is no outside reference
                 * to this block yet. It is not necessary to keep um_lock
                 * locked.
                 */
                if (realsize != 0 && realsize < size) {
                        ffs_blkfree_common(ip->i_ump, ip->i_fs,
                            ip->i_devvp->v_rdev,
                            bp, blkno + ffs_numfrags(fs, realsize),
                            (long)(size - realsize), false);
                }

                bdwrite(bp);
                return (blkno);
        }
        /*
         * check to see if any fragments are already available
         * allocsiz is the size which will be allocated, hacking
         * it down to a smaller size if necessary
         */
        blksfree = cg_blksfree(cgp, needswap);
        frags = ffs_numfrags(fs, size);
        for (allocsiz = frags; allocsiz < fs->fs_frag; allocsiz++)
                if (cgp->cg_frsum[allocsiz] != 0)
                        break;
        if (allocsiz == fs->fs_frag) {
                /*
                 * no fragments were available, so a block will be
                 * allocated, and hacked up
                 */
                if (cgp->cg_cs.cs_nbfree == 0)
                        goto fail;
                mutex_enter(&ump->um_lock);
                blkno = ffs_alloccgblk(ip, bp, bpref, realsize, flags);
                bno = dtogd(fs, blkno);
                for (i = frags; i < fs->fs_frag; i++)
                        setbit(blksfree, bno + i);
                i = fs->fs_frag - frags;
                ufs_add32(cgp->cg_cs.cs_nffree, i, needswap);
                fs->fs_cstotal.cs_nffree += i;
                fs->fs_cs(fs, cg).cs_nffree += i;
                fs->fs_fmod = 1;
                ufs_add32(cgp->cg_frsum[i], 1, needswap);
                ACTIVECG_CLR(fs, cg);
                mutex_exit(&ump->um_lock);
                bdwrite(bp);
                return (blkno);
        }
        bno = ffs_mapsearch(fs, cgp, bpref, allocsiz);
#if 0
        /*
         * XXX fvdl mapsearch will panic, and never return -1
         *          also: returning NULL as daddr_t ?
         */
        if (bno < 0)
                goto fail;
#endif
        for (i = 0; i < frags; i++)
                clrbit(blksfree, bno + i);
        mutex_enter(&ump->um_lock);
        ufs_add32(cgp->cg_cs.cs_nffree, -frags, needswap);
        fs->fs_cstotal.cs_nffree -= frags;
        fs->fs_cs(fs, cg).cs_nffree -= frags;
        fs->fs_fmod = 1;
        ufs_add32(cgp->cg_frsum[allocsiz], -1, needswap);
        if (frags != allocsiz)
                ufs_add32(cgp->cg_frsum[allocsiz - frags], 1, needswap);
        blkno = cgbase(fs, cg) + bno;
        ACTIVECG_CLR(fs, cg);
        mutex_exit(&ump->um_lock);
        bdwrite(bp);
        return blkno;

 fail:
        if (bp != NULL)
                brelse(bp, 0);
        mutex_enter(&ump->um_lock);
        return (0);
}

/*
 * Allocate a block in a cylinder group.
 *
 * This algorithm implements the following policy:
 *   1) allocate the requested block.
 *   2) allocate a rotationally optimal block in the same cylinder.
 *   3) allocate the next available block on the block rotor for the
 *      specified cylinder group.
 * Note that this routine only allocates fs_bsize blocks; these
 * blocks may be fragmented by the routine that allocates them.
 */
static daddr_t
ffs_alloccgblk(struct inode *ip, struct buf *bp, daddr_t bpref, int realsize,
    int flags)
{
        struct fs *fs = ip->i_fs;
        struct cg *cgp;
        int cg;
        daddr_t blkno;
        int32_t bno;
        u_int8_t *blksfree;
        const int needswap = UFS_FSNEEDSWAP(fs);

        KASSERT(mutex_owned(&ip->i_ump->um_lock));

        cgp = (struct cg *)bp->b_data;
        blksfree = cg_blksfree(cgp, needswap);
        if (bpref == 0 || dtog(fs, bpref) != ufs_rw32(cgp->cg_cgx, needswap)) {
                bpref = ufs_rw32(cgp->cg_rotor, needswap);
        } else {
                bpref = ffs_blknum(fs, bpref);
                bno = dtogd(fs, bpref);
                /*
                 * if the requested block is available, use it
                 */
                if (ffs_isblock(fs, blksfree, ffs_fragstoblks(fs, bno)))
                        goto gotit;
                /*
                 * if the requested data block isn't available and we are
                 * trying to allocate a contiguous file, return an error.
                 */
                if ((flags & (B_CONTIG | B_METAONLY)) == B_CONTIG)
                        return (0);
        }

        /*
         * Take the next available block in this cylinder group.
         */
        bno = ffs_mapsearch(fs, cgp, bpref, (int)fs->fs_frag);
#if 0 
        /*
         * XXX jdolecek ffs_mapsearch() succeeds or panics
         */
        if (bno < 0)
                return (0);
#endif
        cgp->cg_rotor = ufs_rw32(bno, needswap);
gotit:
        blkno = ffs_fragstoblks(fs, bno);
        ffs_clrblock(fs, blksfree, blkno);
        ffs_clusteracct(fs, cgp, blkno, -1);
        ufs_add32(cgp->cg_cs.cs_nbfree, -1, needswap);
        fs->fs_cstotal.cs_nbfree--;
        fs->fs_cs(fs, ufs_rw32(cgp->cg_cgx, needswap)).cs_nbfree--;
        if ((fs->fs_magic == FS_UFS1_MAGIC) &&
            ((fs->fs_old_flags & FS_FLAGS_UPDATED) == 0)) {
                int cylno;
                cylno = old_cbtocylno(fs, bno);
                KASSERT(cylno >= 0);
                KASSERT(cylno < fs->fs_old_ncyl);
                KASSERT(old_cbtorpos(fs, bno) >= 0);
                KASSERT(fs->fs_old_nrpos == 0 || old_cbtorpos(fs, bno) < fs->fs_old_nrpos);
                ufs_add16(old_cg_blks(fs, cgp, cylno, needswap)[old_cbtorpos(fs, bno)], -1,
                    needswap);
                ufs_add32(old_cg_blktot(cgp, needswap)[cylno], -1, needswap);
        }
        fs->fs_fmod = 1;
        cg = ufs_rw32(cgp->cg_cgx, needswap);
        blkno = cgbase(fs, cg) + bno;
        return (blkno);
}

/*
 * Determine whether an inode can be allocated.
 *
 * Check to see if an inode is available, and if it is,
 * allocate it using the following policy:
 *   1) allocate the requested inode.
 *   2) allocate the next available inode after the requested
 *      inode in the specified cylinder group.
 */
static daddr_t
ffs_nodealloccg(struct inode *ip, u_int cg, daddr_t ipref, int mode, int realsize,
    int flags)
{
        struct ufsmount *ump = ip->i_ump;
        struct fs *fs = ip->i_fs;
        struct cg *cgp;
        struct buf *bp, *ibp;
        u_int8_t *inosused;
        int error, start, len, loc, map, i;
        int32_t initediblk, maxiblk, irotor;
        daddr_t nalloc;
        struct ufs2_dinode *dp2;
        const int needswap = UFS_FSNEEDSWAP(fs);

        KASSERT(mutex_owned(&ump->um_lock));
        UFS_WAPBL_JLOCK_ASSERT(ip->i_ump->um_mountp);

        if (fs->fs_cs(fs, cg).cs_nifree == 0)
                return (0);
        mutex_exit(&ump->um_lock);
        ibp = NULL;
        if (fs->fs_magic == FS_UFS2_MAGIC) {
                initediblk = -1;
        } else {
                initediblk = fs->fs_ipg;
        }
        maxiblk = initediblk;

retry:
        error = bread(ip->i_devvp, FFS_FSBTODB(fs, cgtod(fs, cg)),
                (int)fs->fs_cgsize, B_MODIFY, &bp);
        if (error)
                goto fail;
        cgp = (struct cg *)bp->b_data;
        if (!cg_chkmagic(cgp, needswap) || cgp->cg_cs.cs_nifree == 0)
                goto fail;

        if (ibp != NULL &&
            initediblk != ufs_rw32(cgp->cg_initediblk, needswap)) {
                /* Another thread allocated more inodes so we retry the test. */
                brelse(ibp, 0);
                ibp = NULL;
        }
        /*
         * Check to see if we need to initialize more inodes.
         */
        if (fs->fs_magic == FS_UFS2_MAGIC && ibp == NULL) {
                initediblk = ufs_rw32(cgp->cg_initediblk, needswap);
                maxiblk = initediblk;
                nalloc = fs->fs_ipg - ufs_rw32(cgp->cg_cs.cs_nifree, needswap);
                if (nalloc + FFS_INOPB(fs) > initediblk &&
                    initediblk < ufs_rw32(cgp->cg_niblk, needswap)) {
                        /*
                         * We have to release the cg buffer here to prevent
                         * a deadlock when reading the inode block will
                         * run a copy-on-write that might use this cg.
                         */
                        brelse(bp, 0);
                        bp = NULL;
                        error = ffs_getblk(ip->i_devvp, FFS_FSBTODB(fs,
                            ino_to_fsba(fs, cg * fs->fs_ipg + initediblk)),
                            FFS_NOBLK, fs->fs_bsize, false, &ibp);
                        if (error)
                                goto fail;

                        maxiblk += FFS_INOPB(fs);
                        
                        goto retry;
                }
        }

        cgp->cg_old_time = ufs_rw32(time_second, needswap);
        if ((fs->fs_magic != FS_UFS1_MAGIC) ||
            (fs->fs_old_flags & FS_FLAGS_UPDATED))
                cgp->cg_time = ufs_rw64(time_second, needswap);
        inosused = cg_inosused(cgp, needswap);
        
        if (ipref) {
                ipref %= fs->fs_ipg;
                /* safeguard to stay in (to be) allocated range */
                if (ipref < maxiblk && isclr(inosused, ipref))
                        goto gotit;
        }

        irotor = ufs_rw32(cgp->cg_irotor, needswap); 

        KASSERTMSG(irotor < initediblk, "%s: allocation botch: cg=%d, irotor %d"
                   " out of bounds, initediblk=%d",
                   __func__, cg, irotor, initediblk);

        start = irotor / NBBY;
        len = howmany(maxiblk - irotor, NBBY);
        loc = skpc(0xff, len, &inosused[start]);
        if (loc == 0) {
                len = start + 1;
                start = 0;
                loc = skpc(0xff, len, &inosused[0]);
                if (loc == 0) {
                        panic("%s: map corrupted: cg=%d, irotor=%d, fs=%s",
                            __func__, cg, ufs_rw32(cgp->cg_irotor, needswap),
                            fs->fs_fsmnt);
                        /* NOTREACHED */
                }
        }
        i = start + len - loc;
        map = inosused[i] ^ 0xff;
        if (map == 0) {
                panic("%s: block not in map: fs=%s", __func__, fs->fs_fsmnt);
        }
        
        ipref = i * NBBY + ffs(map) - 1;

        cgp->cg_irotor = ufs_rw32(ipref, needswap);

gotit:
        KASSERTMSG(ipref < maxiblk, "%s: allocation botch: cg=%d attempt to "
                   "allocate inode index %d beyond max allocated index %d"
                   " of %d inodes/cg",
                   __func__, cg, (int)ipref, maxiblk, cgp->cg_niblk);

        UFS_WAPBL_REGISTER_INODE(ip->i_ump->um_mountp, cg * fs->fs_ipg + ipref,
            mode);
        /*
         * Check to see if we need to initialize more inodes.
         */
        if (ibp != NULL) {
                KASSERT(initediblk == ufs_rw32(cgp->cg_initediblk, needswap));
                memset(ibp->b_data, 0, fs->fs_bsize);
                dp2 = (struct ufs2_dinode *)(ibp->b_data);
                for (i = 0; i < FFS_INOPB(fs); i++) {
                        /*
                         * Don't bother to swap, it's supposed to be
                         * random, after all.
                         */
                        dp2->di_gen = (cprng_fast32() & INT32_MAX) / 2 + 1;
                        dp2++;
                }
                initediblk += FFS_INOPB(fs);
                cgp->cg_initediblk = ufs_rw32(initediblk, needswap);
        }

        mutex_enter(&ump->um_lock);
        ACTIVECG_CLR(fs, cg);
        setbit(inosused, ipref);
        ufs_add32(cgp->cg_cs.cs_nifree, -1, needswap);
        fs->fs_cstotal.cs_nifree--;
        fs->fs_cs(fs, cg).cs_nifree--;
        fs->fs_fmod = 1;
        if ((mode & IFMT) == IFDIR) {
                ufs_add32(cgp->cg_cs.cs_ndir, 1, needswap);
                fs->fs_cstotal.cs_ndir++;
                fs->fs_cs(fs, cg).cs_ndir++;
        }
        mutex_exit(&ump->um_lock);
        if (ibp != NULL) {
                bwrite(ibp);
                bwrite(bp);
        } else
                bdwrite(bp);
        return ((ino_t)(cg * fs->fs_ipg + ipref));
 fail:
        if (bp != NULL)
                brelse(bp, 0);
        if (ibp != NULL)
                brelse(ibp, 0);
        mutex_enter(&ump->um_lock);
        return (0);
}

/*
 * Allocate a block or fragment.
 *
 * The specified block or fragment is removed from the
 * free map, possibly fragmenting a block in the process.
 *
 * This implementation should mirror fs_blkfree
 *
 * => um_lock not held on entry or exit
 */
int
ffs_blkalloc(struct inode *ip, daddr_t bno, long size)
{
        int error;

        error = ffs_check_bad_allocation(__func__, ip->i_fs, bno, size,
            ip->i_dev, ip->i_uid);
        if (error)
                return error;

        return ffs_blkalloc_ump(ip->i_ump, bno, size);
}

int
ffs_blkalloc_ump(struct ufsmount *ump, daddr_t bno, long size)
{
        struct fs *fs = ump->um_fs;
        struct cg *cgp;
        struct buf *bp;
        int32_t fragno, cgbno;
        int i, error, blk, frags, bbase;
        u_int cg;
        u_int8_t *blksfree;
        const int needswap = UFS_FSNEEDSWAP(fs);

        KASSERT((u_int)size <= fs->fs_bsize && ffs_fragoff(fs, size) == 0 &&
            ffs_fragnum(fs, bno) + ffs_numfrags(fs, size) <= fs->fs_frag);
        KASSERT(bno < fs->fs_size);

        cg = dtog(fs, bno);
        error = bread(ump->um_devvp, FFS_FSBTODB(fs, cgtod(fs, cg)),
                (int)fs->fs_cgsize, B_MODIFY, &bp);
        if (error) {
                return error;
        }
        cgp = (struct cg *)bp->b_data;
        if (!cg_chkmagic(cgp, needswap)) {
                brelse(bp, 0);
                return EIO;
        }
        cgp->cg_old_time = ufs_rw32(time_second, needswap);
        cgp->cg_time = ufs_rw64(time_second, needswap);
        cgbno = dtogd(fs, bno);
        blksfree = cg_blksfree(cgp, needswap);

        mutex_enter(&ump->um_lock);
        if (size == fs->fs_bsize) {
                fragno = ffs_fragstoblks(fs, cgbno);
                if (!ffs_isblock(fs, blksfree, fragno)) {
                        mutex_exit(&ump->um_lock);
                        brelse(bp, 0);
                        return EBUSY;
                }
                ffs_clrblock(fs, blksfree, fragno);
                ffs_clusteracct(fs, cgp, fragno, -1);
                ufs_add32(cgp->cg_cs.cs_nbfree, -1, needswap);
                fs->fs_cstotal.cs_nbfree--;
                fs->fs_cs(fs, cg).cs_nbfree--;
        } else {
                bbase = cgbno - ffs_fragnum(fs, cgbno);

                frags = ffs_numfrags(fs, size);
                for (i = 0; i < frags; i++) {
                        if (isclr(blksfree, cgbno + i)) {
                                mutex_exit(&ump->um_lock);
                                brelse(bp, 0);
                                return EBUSY;
                        }
                }
                /*
                 * if a complete block is being split, account for it
                 */
                fragno = ffs_fragstoblks(fs, bbase);
                if (ffs_isblock(fs, blksfree, fragno)) {
                        ufs_add32(cgp->cg_cs.cs_nffree, fs->fs_frag, needswap);
                        fs->fs_cstotal.cs_nffree += fs->fs_frag;
                        fs->fs_cs(fs, cg).cs_nffree += fs->fs_frag;
                        ffs_clusteracct(fs, cgp, fragno, -1);
                        ufs_add32(cgp->cg_cs.cs_nbfree, -1, needswap);
                        fs->fs_cstotal.cs_nbfree--;
                        fs->fs_cs(fs, cg).cs_nbfree--;
                }
                /*
                 * decrement the counts associated with the old frags
                 */
                blk = blkmap(fs, blksfree, bbase);
                ffs_fragacct(fs, blk, cgp->cg_frsum, -1, needswap);
                /*
                 * allocate the fragment
                 */
                for (i = 0; i < frags; i++) {
                        clrbit(blksfree, cgbno + i);
                }
                ufs_add32(cgp->cg_cs.cs_nffree, -i, needswap);
                fs->fs_cstotal.cs_nffree -= i;
                fs->fs_cs(fs, cg).cs_nffree -= i;
                /*
                 * add back in counts associated with the new frags
                 */
                blk = blkmap(fs, blksfree, bbase);
                ffs_fragacct(fs, blk, cgp->cg_frsum, 1, needswap);
        }
        fs->fs_fmod = 1;
        ACTIVECG_CLR(fs, cg);
        mutex_exit(&ump->um_lock);
        bdwrite(bp);
        return 0;
}

/*
 * Free a block or fragment.
 *
 * The specified block or fragment is placed back in the
 * free map. If a fragment is deallocated, a possible
 * block reassembly is checked.
 *
 * => um_lock not held on entry or exit
 */
static void
ffs_blkfree_cg(struct fs *fs, struct vnode *devvp, daddr_t bno, long size)
{
        struct cg *cgp;
        struct buf *bp;
        struct ufsmount *ump;
        daddr_t cgblkno;
        int error;
        u_int cg;
        dev_t dev;
        const bool devvp_is_snapshot = (devvp->v_type != VBLK);
        const int needswap = UFS_FSNEEDSWAP(fs);

        KASSERT(!devvp_is_snapshot);

        cg = dtog(fs, bno);
        dev = devvp->v_rdev;
        ump = VFSTOUFS(spec_node_getmountedfs(devvp));
        KASSERT(fs == ump->um_fs);
        cgblkno = FFS_FSBTODB(fs, cgtod(fs, cg));

        error = bread(devvp, cgblkno, (int)fs->fs_cgsize,
            B_MODIFY, &bp);
        if (error) {
                return;
        }
        cgp = (struct cg *)bp->b_data;
        if (!cg_chkmagic(cgp, needswap)) {
                brelse(bp, 0);
                return;
        }

        ffs_blkfree_common(ump, fs, dev, bp, bno, size, devvp_is_snapshot);

        bdwrite(bp);
}

struct discardopdata {
        struct work wk; /* must be first */
        struct vnode *devvp;
        daddr_t bno;
        long size;
};

struct discarddata {
        struct fs *fs;
        struct discardopdata *entry;
        long maxsize;
        kmutex_t entrylk;
        struct workqueue *wq;
        int wqcnt, wqdraining;
        kmutex_t wqlk;
        kcondvar_t wqcv;
        /* timer for flush? */
};

static void
ffs_blkfree_td(struct fs *fs, struct discardopdata *td)
{
        struct mount *mp = spec_node_getmountedfs(td->devvp);
        long todo;
        int error;

        while (td->size) {
                todo = uimin(td->size,
                  ffs_lfragtosize(fs, (fs->fs_frag - ffs_fragnum(fs, td->bno))));
                error = UFS_WAPBL_BEGIN(mp);
                if (error) {
                        printf("ffs: failed to begin wapbl transaction"
                            " for discard: %d\n", error);
                        break;
                }
                ffs_blkfree_cg(fs, td->devvp, td->bno, todo);
                UFS_WAPBL_END(mp);
                td->bno += ffs_numfrags(fs, todo);
                td->size -= todo;
        }
}

static void
ffs_discardcb(struct work *wk, void *arg)
{
        struct discardopdata *td = (void *)wk;
        struct discarddata *ts = arg;
        struct fs *fs = ts->fs;
        off_t start, len;
#ifdef TRIMDEBUG
        int error;
#endif

/* like FSBTODB but emits bytes; XXX move to fs.h */
#ifndef FFS_FSBTOBYTES
#define FFS_FSBTOBYTES(fs, b) ((b) << (fs)->fs_fshift)
#endif

        start = FFS_FSBTOBYTES(fs, td->bno);
        len = td->size;
        vn_lock(td->devvp, LK_EXCLUSIVE | LK_RETRY);
#ifdef TRIMDEBUG
        error =
#endif
                VOP_FDISCARD(td->devvp, start, len);
        VOP_UNLOCK(td->devvp);
#ifdef TRIMDEBUG
        printf("trim(%" PRId64 ",%ld):%d\n", td->bno, td->size, error);
#endif

        ffs_blkfree_td(fs, td);
        kmem_free(td, sizeof(*td));
        mutex_enter(&ts->wqlk);
        ts->wqcnt--;
        if (ts->wqdraining && !ts->wqcnt)
                cv_signal(&ts->wqcv);
        mutex_exit(&ts->wqlk);
}

void *
ffs_discard_init(struct vnode *devvp, struct fs *fs)
{
        struct discarddata *ts;
        int error;

        ts = kmem_zalloc(sizeof (*ts), KM_SLEEP);
        error = workqueue_create(&ts->wq, "trimwq", ffs_discardcb, ts,
                                 PRI_USER, IPL_NONE, 0);
        if (error) {
                kmem_free(ts, sizeof (*ts));
                return NULL;
        }
        mutex_init(&ts->entrylk, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&ts->wqlk, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&ts->wqcv, "trimwqcv");
        ts->maxsize = 100*1024; /* XXX */
        ts->fs = fs;
        return ts;
}

void
ffs_discard_finish(void *vts, int flags)
{
        struct discarddata *ts = vts;
        struct discardopdata *td = NULL;

        /* wait for workqueue to drain */
        mutex_enter(&ts->wqlk);
        if (ts->wqcnt) {
                ts->wqdraining = 1;
                cv_wait(&ts->wqcv, &ts->wqlk);
        }
        mutex_exit(&ts->wqlk);

        mutex_enter(&ts->entrylk);
        if (ts->entry) {
                td = ts->entry;
                ts->entry = NULL;
        }
        mutex_exit(&ts->entrylk);
        if (td) {
                /* XXX don't tell disk, its optional */
                ffs_blkfree_td(ts->fs, td);
#ifdef TRIMDEBUG
                printf("finish(%" PRId64 ",%ld)\n", td->bno, td->size);
#endif
                kmem_free(td, sizeof(*td));
        }

        cv_destroy(&ts->wqcv);
        mutex_destroy(&ts->entrylk);
        mutex_destroy(&ts->wqlk);
        workqueue_destroy(ts->wq);
        kmem_free(ts, sizeof(*ts));
}

void
ffs_blkfree(struct fs *fs, struct vnode *devvp, daddr_t bno, long size,
    ino_t inum)
{
        struct ufsmount *ump;
        int error;
        dev_t dev;
        struct discarddata *ts;
        struct discardopdata *td;

        dev = devvp->v_rdev;
        ump = VFSTOUFS(spec_node_getmountedfs(devvp));
        if (ffs_snapblkfree(fs, devvp, bno, size, inum))
                return;

        error = ffs_check_bad_allocation(__func__, fs, bno, size, dev, inum);
        if (error)
                return;

        if (!ump->um_discarddata) {
                ffs_blkfree_cg(fs, devvp, bno, size);
                return;
        }

#ifdef TRIMDEBUG
        printf("blkfree(%" PRId64 ",%ld)\n", bno, size);
#endif
        ts = ump->um_discarddata;
        td = NULL;

        mutex_enter(&ts->entrylk);
        if (ts->entry) {
                td = ts->entry;
                /* ffs deallocs backwards, check for prepend only */
                if (td->bno == bno + ffs_numfrags(fs, size)
                    && td->size + size <= ts->maxsize) {
                        td->bno = bno;
                        td->size += size;
                        if (td->size < ts->maxsize) {
#ifdef TRIMDEBUG
                                printf("defer(%" PRId64 ",%ld)\n", td->bno, td->size);
#endif
                                mutex_exit(&ts->entrylk);
                                return;
                        }
                        size = 0; /* mark done */
                }
                ts->entry = NULL;
        }
        mutex_exit(&ts->entrylk);

        if (td) {
#ifdef TRIMDEBUG
                printf("enq old(%" PRId64 ",%ld)\n", td->bno, td->size);
#endif
                mutex_enter(&ts->wqlk);
                ts->wqcnt++;
                mutex_exit(&ts->wqlk);
                workqueue_enqueue(ts->wq, &td->wk, NULL);
        }
        if (!size)
                return;

        td = kmem_alloc(sizeof(*td), KM_SLEEP);
        td->devvp = devvp;
        td->bno = bno;
        td->size = size;

        if (td->size < ts->maxsize) { /* XXX always the case */
                mutex_enter(&ts->entrylk);
                if (!ts->entry) { /* possible race? */
#ifdef TRIMDEBUG
                        printf("defer(%" PRId64 ",%ld)\n", td->bno, td->size);
#endif
                        ts->entry = td;
                        td = NULL;
                }
                mutex_exit(&ts->entrylk);
        }
        if (td) {
#ifdef TRIMDEBUG
                printf("enq new(%" PRId64 ",%ld)\n", td->bno, td->size);
#endif
                mutex_enter(&ts->wqlk);
                ts->wqcnt++;
                mutex_exit(&ts->wqlk);
                workqueue_enqueue(ts->wq, &td->wk, NULL);
        }
}

/*
 * Free a block or fragment from a snapshot cg copy.
 *
 * The specified block or fragment is placed back in the
 * free map. If a fragment is deallocated, a possible
 * block reassembly is checked.
 *
 * => um_lock not held on entry or exit
 */
void
ffs_blkfree_snap(struct fs *fs, struct vnode *devvp, daddr_t bno, long size,
    ino_t inum)
{
        struct cg *cgp;
        struct buf *bp;
        struct ufsmount *ump;
        daddr_t cgblkno;
        int error, cg;
        dev_t dev;
        const bool devvp_is_snapshot = (devvp->v_type != VBLK);
        const int needswap = UFS_FSNEEDSWAP(fs);

        KASSERT(devvp_is_snapshot);

        cg = dtog(fs, bno);
        dev = VTOI(devvp)->i_devvp->v_rdev;
        ump = VFSTOUFS(devvp->v_mount);
        cgblkno = ffs_fragstoblks(fs, cgtod(fs, cg));

        error = ffs_check_bad_allocation(__func__, fs, bno, size, dev, inum);
        if (error)
                return;

        error = bread(devvp, cgblkno, (int)fs->fs_cgsize,
            B_MODIFY, &bp);
        if (error) {
                return;
        }
        cgp = (struct cg *)bp->b_data;
        if (!cg_chkmagic(cgp, needswap)) {
                brelse(bp, 0);
                return;
        }

        ffs_blkfree_common(ump, fs, dev, bp, bno, size, devvp_is_snapshot);

        bdwrite(bp);
}

static void
ffs_blkfree_common(struct ufsmount *ump, struct fs *fs, dev_t dev,
    struct buf *bp, daddr_t bno, long size, bool devvp_is_snapshot)
{
        struct cg *cgp;
        int32_t fragno, cgbno;
        int i, blk, frags, bbase;
        u_int cg;
        u_int8_t *blksfree;
        const int needswap = UFS_FSNEEDSWAP(fs);

        cg = dtog(fs, bno);
        cgp = (struct cg *)bp->b_data;
        cgp->cg_old_time = ufs_rw32(time_second, needswap);
        if ((fs->fs_magic != FS_UFS1_MAGIC) ||
            (fs->fs_old_flags & FS_FLAGS_UPDATED))
                cgp->cg_time = ufs_rw64(time_second, needswap);
        cgbno = dtogd(fs, bno);
        blksfree = cg_blksfree(cgp, needswap);
        mutex_enter(&ump->um_lock);
        if (size == fs->fs_bsize) {
                fragno = ffs_fragstoblks(fs, cgbno);
                if (!ffs_isfreeblock(fs, blksfree, fragno)) {
                        if (devvp_is_snapshot) {
                                mutex_exit(&ump->um_lock);
                                return;
                        }
                        panic("%s: freeing free block: dev = 0x%llx, block = %"
                            PRId64 ", fs = %s", __func__,
                            (unsigned long long)dev, bno, fs->fs_fsmnt);
                }
                ffs_setblock(fs, blksfree, fragno);
                ffs_clusteracct(fs, cgp, fragno, 1);
                ufs_add32(cgp->cg_cs.cs_nbfree, 1, needswap);
                fs->fs_cstotal.cs_nbfree++;
                fs->fs_cs(fs, cg).cs_nbfree++;
                if ((fs->fs_magic == FS_UFS1_MAGIC) &&
                    ((fs->fs_old_flags & FS_FLAGS_UPDATED) == 0)) {
                        i = old_cbtocylno(fs, cgbno);
                        KASSERT(i >= 0);
                        KASSERT(i < fs->fs_old_ncyl);
                        KASSERT(old_cbtorpos(fs, cgbno) >= 0);
                        KASSERT(fs->fs_old_nrpos == 0 || old_cbtorpos(fs, cgbno) < fs->fs_old_nrpos);
                        ufs_add16(old_cg_blks(fs, cgp, i, needswap)[old_cbtorpos(fs, cgbno)], 1,
                            needswap);
                        ufs_add32(old_cg_blktot(cgp, needswap)[i], 1, needswap);
                }
        } else {
                bbase = cgbno - ffs_fragnum(fs, cgbno);
                /*
                 * decrement the counts associated with the old frags
                 */
                blk = blkmap(fs, blksfree, bbase);
                ffs_fragacct(fs, blk, cgp->cg_frsum, -1, needswap);
                /*
                 * deallocate the fragment
                 */
                frags = ffs_numfrags(fs, size);
                for (i = 0; i < frags; i++) {
                        if (isset(blksfree, cgbno + i)) {
                                panic("%s: freeing free frag: "
                                    "dev = 0x%llx, block = %" PRId64
                                    ", fs = %s", __func__,
                                    (unsigned long long)dev, bno + i,
                                    fs->fs_fsmnt);
                        }
                        setbit(blksfree, cgbno + i);
                }
                ufs_add32(cgp->cg_cs.cs_nffree, i, needswap);
                fs->fs_cstotal.cs_nffree += i;
                fs->fs_cs(fs, cg).cs_nffree += i;
                /*
                 * add back in counts associated with the new frags
                 */
                blk = blkmap(fs, blksfree, bbase);
                ffs_fragacct(fs, blk, cgp->cg_frsum, 1, needswap);
                /*
                 * if a complete block has been reassembled, account for it
                 */
                fragno = ffs_fragstoblks(fs, bbase);
                if (ffs_isblock(fs, blksfree, fragno)) {
                        ufs_add32(cgp->cg_cs.cs_nffree, -fs->fs_frag, needswap);
                        fs->fs_cstotal.cs_nffree -= fs->fs_frag;
                        fs->fs_cs(fs, cg).cs_nffree -= fs->fs_frag;
                        ffs_clusteracct(fs, cgp, fragno, 1);
                        ufs_add32(cgp->cg_cs.cs_nbfree, 1, needswap);
                        fs->fs_cstotal.cs_nbfree++;
                        fs->fs_cs(fs, cg).cs_nbfree++;
                        if ((fs->fs_magic == FS_UFS1_MAGIC) &&
                            ((fs->fs_old_flags & FS_FLAGS_UPDATED) == 0)) {
                                i = old_cbtocylno(fs, bbase);
                                KASSERT(i >= 0);
                                KASSERT(i < fs->fs_old_ncyl);
                                KASSERT(old_cbtorpos(fs, bbase) >= 0);
                                KASSERT(fs->fs_old_nrpos == 0 || old_cbtorpos(fs, bbase) < fs->fs_old_nrpos);
                                ufs_add16(old_cg_blks(fs, cgp, i, needswap)[old_cbtorpos(fs,
                                    bbase)], 1, needswap);
                                ufs_add32(old_cg_blktot(cgp, needswap)[i], 1, needswap);
                        }
                }
        }
        fs->fs_fmod = 1;
        ACTIVECG_CLR(fs, cg);
        mutex_exit(&ump->um_lock);
}

/*
 * Free an inode.
 */
int
ffs_vfree(struct vnode *vp, ino_t ino, int mode)
{

        return ffs_freefile(vp->v_mount, ino, mode);
}

/*
 * Do the actual free operation.
 * The specified inode is placed back in the free map.
 *
 * => um_lock not held on entry or exit
 */
int
ffs_freefile(struct mount *mp, ino_t ino, int mode)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct fs *fs = ump->um_fs;
        struct vnode *devvp;
        struct cg *cgp;
        struct buf *bp;
        int error;
        u_int cg;
        daddr_t cgbno;
        dev_t dev;
        const int needswap = UFS_FSNEEDSWAP(fs);

        cg = ino_to_cg(fs, ino);
        devvp = ump->um_devvp;
        dev = devvp->v_rdev;
        cgbno = FFS_FSBTODB(fs, cgtod(fs, cg));

        if (ino >= fs->fs_ipg * fs->fs_ncg)
                panic("%s: range: dev = 0x%llx, ino = %llu, fs = %s", __func__,
                    (long long)dev, (unsigned long long)ino, fs->fs_fsmnt);
        error = bread(devvp, cgbno, (int)fs->fs_cgsize,
            B_MODIFY, &bp);
        if (error) {
                return (error);
        }
        cgp = (struct cg *)bp->b_data;
        if (!cg_chkmagic(cgp, needswap)) {
                brelse(bp, 0);
                return (0);
        }

        ffs_freefile_common(ump, fs, dev, bp, ino, mode, false);

        bdwrite(bp);

        return 0;
}

int
ffs_freefile_snap(struct fs *fs, struct vnode *devvp, ino_t ino, int mode)
{
        struct ufsmount *ump;
        struct cg *cgp;
        struct buf *bp;
        int error, cg;
        daddr_t cgbno;
        dev_t dev;
        const int needswap = UFS_FSNEEDSWAP(fs);

        KASSERT(devvp->v_type != VBLK);

        cg = ino_to_cg(fs, ino);
        dev = VTOI(devvp)->i_devvp->v_rdev;
        ump = VFSTOUFS(devvp->v_mount);
        cgbno = ffs_fragstoblks(fs, cgtod(fs, cg));
        if (ino >= fs->fs_ipg * fs->fs_ncg)
                panic("%s: range: dev = 0x%llx, ino = %llu, fs = %s", __func__,
                    (unsigned long long)dev, (unsigned long long)ino,
                    fs->fs_fsmnt);
        error = bread(devvp, cgbno, (int)fs->fs_cgsize,
            B_MODIFY, &bp);
        if (error) {
                return (error);
        }
        cgp = (struct cg *)bp->b_data;
        if (!cg_chkmagic(cgp, needswap)) {
                brelse(bp, 0);
                return (0);
        }
        ffs_freefile_common(ump, fs, dev, bp, ino, mode, true);

        bdwrite(bp);

        return 0;
}

static void
ffs_freefile_common(struct ufsmount *ump, struct fs *fs, dev_t dev,
    struct buf *bp, ino_t ino, int mode, bool devvp_is_snapshot)
{
        u_int cg;
        struct cg *cgp;
        u_int8_t *inosused;
        const int needswap = UFS_FSNEEDSWAP(fs);
        ino_t cgino;

        cg = ino_to_cg(fs, ino);
        cgp = (struct cg *)bp->b_data;
        cgp->cg_old_time = ufs_rw32(time_second, needswap);
        if ((fs->fs_magic != FS_UFS1_MAGIC) ||
            (fs->fs_old_flags & FS_FLAGS_UPDATED))
                cgp->cg_time = ufs_rw64(time_second, needswap);
        inosused = cg_inosused(cgp, needswap);
        cgino = ino % fs->fs_ipg;
        if (isclr(inosused, cgino)) {
                printf("ifree: dev = 0x%llx, ino = %llu, fs = %s\n",
                    (unsigned long long)dev, (unsigned long long)ino,
                    fs->fs_fsmnt);
                if (fs->fs_ronly == 0)
                        panic("%s: freeing free inode", __func__);
        }
        clrbit(inosused, cgino);
        if (!devvp_is_snapshot)
                UFS_WAPBL_UNREGISTER_INODE(ump->um_mountp, ino, mode);
        if (cgino < ufs_rw32(cgp->cg_irotor, needswap))
                cgp->cg_irotor = ufs_rw32(cgino, needswap);
        ufs_add32(cgp->cg_cs.cs_nifree, 1, needswap);
        mutex_enter(&ump->um_lock);
        fs->fs_cstotal.cs_nifree++;
        fs->fs_cs(fs, cg).cs_nifree++;
        if ((mode & IFMT) == IFDIR) {
                ufs_add32(cgp->cg_cs.cs_ndir, -1, needswap);
                fs->fs_cstotal.cs_ndir--;
                fs->fs_cs(fs, cg).cs_ndir--;
        }
        fs->fs_fmod = 1;
        ACTIVECG_CLR(fs, cg);
        mutex_exit(&ump->um_lock);
}

/*
 * Check to see if a file is free.
 */
int
ffs_checkfreefile(struct fs *fs, struct vnode *devvp, ino_t ino)
{
        struct cg *cgp;
        struct buf *bp;
        daddr_t cgbno;
        int ret;
        u_int cg;
        u_int8_t *inosused;
        const bool devvp_is_snapshot = (devvp->v_type != VBLK);

        KASSERT(devvp_is_snapshot);

        cg = ino_to_cg(fs, ino);
        if (devvp_is_snapshot)
                cgbno = ffs_fragstoblks(fs, cgtod(fs, cg));
        else
                cgbno = FFS_FSBTODB(fs, cgtod(fs, cg));
        if (ino >= fs->fs_ipg * fs->fs_ncg)
                return 1;
        if (bread(devvp, cgbno, (int)fs->fs_cgsize, 0, &bp)) {
                return 1;
        }
        cgp = (struct cg *)bp->b_data;
        if (!cg_chkmagic(cgp, UFS_FSNEEDSWAP(fs))) {
                brelse(bp, 0);
                return 1;
        }
        inosused = cg_inosused(cgp, UFS_FSNEEDSWAP(fs));
        ino %= fs->fs_ipg;
        ret = isclr(inosused, ino);
        brelse(bp, 0);
        return ret;
}

/*
 * Find a block of the specified size in the specified cylinder group.
 *
 * It is a panic if a request is made to find a block if none are
 * available.
 */
static int32_t
ffs_mapsearch(struct fs *fs, struct cg *cgp, daddr_t bpref, int allocsiz)
{
        int32_t bno;
        int start, len, loc, i;
        int blk, field, subfield, pos;
        int ostart, olen;
        u_int8_t *blksfree;
        const int needswap = UFS_FSNEEDSWAP(fs);

        /* KASSERT(mutex_owned(&ump->um_lock)); */

        /*
         * find the fragment by searching through the free block
         * map for an appropriate bit pattern
         */
        if (bpref)
                start = dtogd(fs, bpref) / NBBY;
        else
                start = ufs_rw32(cgp->cg_frotor, needswap) / NBBY;
        blksfree = cg_blksfree(cgp, needswap);
        len = howmany(fs->fs_fpg, NBBY) - start;
        ostart = start;
        olen = len;
        loc = scanc((u_int)len,
                (const u_char *)&blksfree[start],
                (const u_char *)fragtbl[fs->fs_frag],
                (1 << (allocsiz - 1 + (fs->fs_frag & (NBBY - 1)))));
        if (loc == 0) {
                len = start + 1;
                start = 0;
                loc = scanc((u_int)len,
                        (const u_char *)&blksfree[0],
                        (const u_char *)fragtbl[fs->fs_frag],
                        (1 << (allocsiz - 1 + (fs->fs_frag & (NBBY - 1)))));
                if (loc == 0) {
                        panic("%s: map corrupted: start=%d, len=%d, "
                            "fs = %s, offset=%d/%ld, cg %d", __func__,
                            ostart, olen, fs->fs_fsmnt,
                            ufs_rw32(cgp->cg_freeoff, needswap),
                            (long)blksfree - (long)cgp, cgp->cg_cgx);
                        /* NOTREACHED */
                }
        }
        bno = (start + len - loc) * NBBY;
        cgp->cg_frotor = ufs_rw32(bno, needswap);
        /*
         * found the byte in the map
         * sift through the bits to find the selected frag
         */
        for (i = bno + NBBY; bno < i; bno += fs->fs_frag) {
                blk = blkmap(fs, blksfree, bno);
                blk <<= 1;
                field = around[allocsiz];
                subfield = inside[allocsiz];
                for (pos = 0; pos <= fs->fs_frag - allocsiz; pos++) {
                        if ((blk & field) == subfield)
                                return (bno + pos);
                        field <<= 1;
                        subfield <<= 1;
                }
        }
        panic("%s: block not in map: bno=%d, fs=%s", __func__,
            bno, fs->fs_fsmnt);
        /* return (-1); */
}

/*
 * Fserr prints the name of a file system with an error diagnostic.
 *
 * The form of the error message is:
 *      fs: error message
 */
static void
ffs_fserr(struct fs *fs, kauth_cred_t cred, const char *cp)
{
        KASSERT(cred != NULL);

        if (cred == NOCRED || cred == FSCRED) {
                log(LOG_ERR, "pid %d, command %s, on %s: %s\n",
                    curproc->p_pid, curproc->p_comm,
                    fs->fs_fsmnt, cp);
        } else {
                log(LOG_ERR, "uid %d, pid %d, command %s, on %s: %s\n",
                    kauth_cred_getuid(cred), curproc->p_pid, curproc->p_comm,
                    fs->fs_fsmnt, cp);
        }
}