vm: fix a null dereference on out-of-memory

[minix.git] / sys / ufs / lfs / lfs_inode.c

/*      $NetBSD: lfs_inode.c,v 1.126 2011/11/23 19:42:10 bouyer Exp $   */

/*-
 * Copyright (c) 1999, 2000, 2001, 2002, 2003 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Konrad E. Schroder <perseant@hhhh.org>.
 *
 * 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) 1986, 1989, 1991, 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.
 *
 *      @(#)lfs_inode.c 8.9 (Berkeley) 5/8/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: lfs_inode.c,v 1.126 2011/11/23 19:42:10 bouyer Exp $");

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/file.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/kernel.h>
#include <sys/trace.h>
#include <sys/resourcevar.h>
#include <sys/kauth.h>

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

#include <ufs/lfs/lfs.h>
#include <ufs/lfs/lfs_extern.h>

static int lfs_update_seguse(struct lfs *, struct inode *ip, long, size_t);
static int lfs_indirtrunc (struct inode *, daddr_t, daddr_t,
                           daddr_t, int, long *, long *, long *, size_t *);
static int lfs_blkfree (struct lfs *, struct inode *, daddr_t, size_t, long *, size_t *);
static int lfs_vtruncbuf(struct vnode *, daddr_t, bool, int);

/* Search a block for a specific dinode. */
struct ufs1_dinode *
lfs_ifind(struct lfs *fs, ino_t ino, struct buf *bp)
{
        struct ufs1_dinode *dip = (struct ufs1_dinode *)bp->b_data;
        struct ufs1_dinode *ldip, *fin;

        ASSERT_NO_SEGLOCK(fs);
        /*
         * Read the inode block backwards, since later versions of the
         * inode will supercede earlier ones.  Though it is unlikely, it is
         * possible that the same inode will appear in the same inode block.
         */
        fin = dip + INOPB(fs);
        for (ldip = fin - 1; ldip >= dip; --ldip)
                if (ldip->di_inumber == ino)
                        return (ldip);

        printf("searched %d entries\n", (int)(fin - dip));
        printf("offset is 0x%x (seg %d)\n", fs->lfs_offset,
               dtosn(fs, fs->lfs_offset));
        printf("block is 0x%llx (seg %lld)\n",
               (unsigned long long)dbtofsb(fs, bp->b_blkno),
               (long long)dtosn(fs, dbtofsb(fs, bp->b_blkno)));

        return NULL;
}

int
lfs_update(struct vnode *vp, const struct timespec *acc,
    const struct timespec *mod, int updflags)
{
        struct inode *ip;
        struct lfs *fs = VFSTOUFS(vp->v_mount)->um_lfs;
        int flags;

        ASSERT_NO_SEGLOCK(fs);
        if (vp->v_mount->mnt_flag & MNT_RDONLY)
                return (0);
        ip = VTOI(vp);

        /*
         * If we are called from vinvalbuf, and the file's blocks have
         * already been scheduled for writing, but the writes have not
         * yet completed, lfs_vflush will not be called, and vinvalbuf
         * will cause a panic.  So, we must wait until any pending write
         * for our inode completes, if we are called with UPDATE_WAIT set.
         */
        mutex_enter(vp->v_interlock);
        while ((updflags & (UPDATE_WAIT|UPDATE_DIROP)) == UPDATE_WAIT &&
            WRITEINPROG(vp)) {
                DLOG((DLOG_SEG, "lfs_update: sleeping on ino %d"
                      " (in progress)\n", ip->i_number));
                cv_wait(&vp->v_cv, vp->v_interlock);
        }
        mutex_exit(vp->v_interlock);
        LFS_ITIMES(ip, acc, mod, NULL);
        if (updflags & UPDATE_CLOSE)
                flags = ip->i_flag & (IN_MODIFIED | IN_ACCESSED | IN_CLEANING);
        else
                flags = ip->i_flag & (IN_MODIFIED | IN_CLEANING);
        if (flags == 0)
                return (0);

        /* If sync, push back the vnode and any dirty blocks it may have. */
        if ((updflags & (UPDATE_WAIT|UPDATE_DIROP)) == UPDATE_WAIT) {
                /* Avoid flushing VU_DIROP. */
                mutex_enter(&lfs_lock);
                ++fs->lfs_diropwait;
                while (vp->v_uflag & VU_DIROP) {
                        DLOG((DLOG_DIROP, "lfs_update: sleeping on inode %d"
                              " (dirops)\n", ip->i_number));
                        DLOG((DLOG_DIROP, "lfs_update: vflags 0x%x, iflags"
                              " 0x%x\n",
                              vp->v_iflag | vp->v_vflag | vp->v_uflag,
                              ip->i_flag));
                        if (fs->lfs_dirops == 0)
                                lfs_flush_fs(fs, SEGM_SYNC);
                        else
                                mtsleep(&fs->lfs_writer, PRIBIO+1, "lfs_fsync",
                                        0, &lfs_lock);
                        /* XXX KS - by falling out here, are we writing the vn
                        twice? */
                }
                --fs->lfs_diropwait;
                mutex_exit(&lfs_lock);
                return lfs_vflush(vp);
        }
        return 0;
}

#define SINGLE  0       /* index of single indirect block */
#define DOUBLE  1       /* index of double indirect block */
#define TRIPLE  2       /* index of triple indirect block */
/*
 * Truncate the inode oip to at most length size, freeing the
 * disk blocks.
 */
/* VOP_BWRITE 1 + NIADDR + lfs_balloc == 2 + 2*NIADDR times */

int
lfs_truncate(struct vnode *ovp, off_t length, int ioflag, kauth_cred_t cred)
{
        daddr_t lastblock;
        struct inode *oip = VTOI(ovp);
        daddr_t bn, lbn, lastiblock[NIADDR], indir_lbn[NIADDR];
        /* XXX ondisk32 */
        int32_t newblks[NDADDR + NIADDR];
        struct lfs *fs;
        struct buf *bp;
        int offset, size, level;
        long count, rcount, blocksreleased = 0, real_released = 0;
        int i, nblocks;
        int aflags, error, allerror = 0;
        off_t osize;
        long lastseg;
        size_t bc;
        int obufsize, odb;
        int usepc;
        struct ufsmount *ump = oip->i_ump;

        if (ovp->v_type == VCHR || ovp->v_type == VBLK ||
            ovp->v_type == VFIFO || ovp->v_type == VSOCK) {
                KASSERT(oip->i_size == 0);
                return 0;
        }

        if (length < 0)
                return (EINVAL);

        /*
         * Just return and not update modification times.
         */
        if (oip->i_size == length) {
                /* still do a uvm_vnp_setsize() as writesize may be larger */
                uvm_vnp_setsize(ovp, length);
                return (0);
        }

        if (ovp->v_type == VLNK &&
            (oip->i_size < ump->um_maxsymlinklen ||
             (ump->um_maxsymlinklen == 0 &&
              oip->i_ffs1_blocks == 0))) {
#ifdef DIAGNOSTIC
                if (length != 0)
                        panic("lfs_truncate: partial truncate of symlink");
#endif
                memset((char *)SHORTLINK(oip), 0, (u_int)oip->i_size);
                oip->i_size = oip->i_ffs1_size = 0;
                oip->i_flag |= IN_CHANGE | IN_UPDATE;
                return (lfs_update(ovp, NULL, NULL, 0));
        }
        if (oip->i_size == length) {
                oip->i_flag |= IN_CHANGE | IN_UPDATE;
                return (lfs_update(ovp, NULL, NULL, 0));
        }
        fs = oip->i_lfs;
        lfs_imtime(fs);
        osize = oip->i_size;
        usepc = (ovp->v_type == VREG && ovp != fs->lfs_ivnode);

        ASSERT_NO_SEGLOCK(fs);
        /*
         * Lengthen the size of the file. We must ensure that the
         * last byte of the file is allocated. Since the smallest
         * value of osize is 0, length will be at least 1.
         */
        if (osize < length) {
                if (length > ump->um_maxfilesize)
                        return (EFBIG);
                aflags = B_CLRBUF;
                if (ioflag & IO_SYNC)
                        aflags |= B_SYNC;
                if (usepc) {
                        if (lblkno(fs, osize) < NDADDR &&
                            lblkno(fs, osize) != lblkno(fs, length) &&
                            blkroundup(fs, osize) != osize) {
                                off_t eob;

                                eob = blkroundup(fs, osize);
                                uvm_vnp_setwritesize(ovp, eob);
                                error = ufs_balloc_range(ovp, osize,
                                    eob - osize, cred, aflags);
                                if (error) {
                                        (void) lfs_truncate(ovp, osize,
                                                    ioflag & IO_SYNC, cred);
                                        return error;
                                }
                                if (ioflag & IO_SYNC) {
                                        mutex_enter(ovp->v_interlock);
                                        VOP_PUTPAGES(ovp,
                                            trunc_page(osize & fs->lfs_bmask),
                                            round_page(eob),
                                            PGO_CLEANIT | PGO_SYNCIO);
                                }
                        }
                        uvm_vnp_setwritesize(ovp, length);
                        error = ufs_balloc_range(ovp, length - 1, 1, cred,
                                                 aflags);
                        if (error) {
                                (void) lfs_truncate(ovp, osize,
                                                    ioflag & IO_SYNC, cred);
                                return error;
                        }
                        uvm_vnp_setsize(ovp, length);
                        oip->i_flag |= IN_CHANGE | IN_UPDATE;
                        KASSERT(ovp->v_size == oip->i_size);
                        oip->i_lfs_hiblk = lblkno(fs, oip->i_size + fs->lfs_bsize - 1) - 1;
                        return (lfs_update(ovp, NULL, NULL, 0));
                } else {
                        error = lfs_reserve(fs, ovp, NULL,
                            btofsb(fs, (NIADDR + 2) << fs->lfs_bshift));
                        if (error)
                                return (error);
                        error = lfs_balloc(ovp, length - 1, 1, cred,
                                           aflags, &bp);
                        lfs_reserve(fs, ovp, NULL,
                            -btofsb(fs, (NIADDR + 2) << fs->lfs_bshift));
                        if (error)
                                return (error);
                        oip->i_ffs1_size = oip->i_size = length;
                        uvm_vnp_setsize(ovp, length);
                        (void) VOP_BWRITE(bp->b_vp, bp);
                        oip->i_flag |= IN_CHANGE | IN_UPDATE;
                        oip->i_lfs_hiblk = lblkno(fs, oip->i_size + fs->lfs_bsize - 1) - 1;
                        return (lfs_update(ovp, NULL, NULL, 0));
                }
        }

        if ((error = lfs_reserve(fs, ovp, NULL,
            btofsb(fs, (2 * NIADDR + 3) << fs->lfs_bshift))) != 0)
                return (error);

        /*
         * Shorten the size of the file. If the file is not being
         * truncated to a block boundary, the contents of the
         * partial block following the end of the file must be
         * zero'ed in case it ever becomes accessible again because
         * of subsequent file growth. Directories however are not
         * zero'ed as they should grow back initialized to empty.
         */
        offset = blkoff(fs, length);
        lastseg = -1;
        bc = 0;

        if (ovp != fs->lfs_ivnode)
                lfs_seglock(fs, SEGM_PROT);
        if (offset == 0) {
                oip->i_size = oip->i_ffs1_size = length;
        } else if (!usepc) {
                lbn = lblkno(fs, length);
                aflags = B_CLRBUF;
                if (ioflag & IO_SYNC)
                        aflags |= B_SYNC;
                error = lfs_balloc(ovp, length - 1, 1, cred, aflags, &bp);
                if (error) {
                        lfs_reserve(fs, ovp, NULL,
                            -btofsb(fs, (2 * NIADDR + 3) << fs->lfs_bshift));
                        goto errout;
                }
                obufsize = bp->b_bufsize;
                odb = btofsb(fs, bp->b_bcount);
                oip->i_size = oip->i_ffs1_size = length;
                size = blksize(fs, oip, lbn);
                if (ovp->v_type != VDIR)
                        memset((char *)bp->b_data + offset, 0,
                               (u_int)(size - offset));
                allocbuf(bp, size, 1);
                if ((bp->b_flags & B_LOCKED) != 0 && bp->b_iodone == NULL) {
                        mutex_enter(&lfs_lock);
                        locked_queue_bytes -= obufsize - bp->b_bufsize;
                        mutex_exit(&lfs_lock);
                }
                if (bp->b_oflags & BO_DELWRI)
                        fs->lfs_avail += odb - btofsb(fs, size);
                (void) VOP_BWRITE(bp->b_vp, bp);
        } else { /* vp->v_type == VREG && length < osize && offset != 0 */
                /*
                 * When truncating a regular file down to a non-block-aligned
                 * size, we must zero the part of last block which is past
                 * the new EOF.  We must synchronously flush the zeroed pages
                 * to disk since the new pages will be invalidated as soon
                 * as we inform the VM system of the new, smaller size.
                 * We must do this before acquiring the GLOCK, since fetching
                 * the pages will acquire the GLOCK internally.
                 * So there is a window where another thread could see a whole
                 * zeroed page past EOF, but that's life.
                 */
                daddr_t xlbn;
                voff_t eoz;

                aflags = ioflag & IO_SYNC ? B_SYNC : 0;
                error = ufs_balloc_range(ovp, length - 1, 1, cred, aflags);
                if (error) {
                        lfs_reserve(fs, ovp, NULL,
                                    -btofsb(fs, (2 * NIADDR + 3) << fs->lfs_bshift));
                        goto errout;
                }
                xlbn = lblkno(fs, length);
                size = blksize(fs, oip, xlbn);
                eoz = MIN(lblktosize(fs, xlbn) + size, osize);
                ubc_zerorange(&ovp->v_uobj, length, eoz - length,
                    UBC_UNMAP_FLAG(ovp));
                if (round_page(eoz) > round_page(length)) {
                        mutex_enter(ovp->v_interlock);
                        error = VOP_PUTPAGES(ovp, round_page(length),
                            round_page(eoz),
                            PGO_CLEANIT | PGO_DEACTIVATE |
                            ((ioflag & IO_SYNC) ? PGO_SYNCIO : 0));
                        if (error) {
                                lfs_reserve(fs, ovp, NULL,
                                            -btofsb(fs, (2 * NIADDR + 3) << fs->lfs_bshift));
                                goto errout;
                        }
                }
        }

        genfs_node_wrlock(ovp);

        oip->i_size = oip->i_ffs1_size = length;
        uvm_vnp_setsize(ovp, length);

        /*
         * Calculate index into inode's block list of
         * last direct and indirect blocks (if any)
         * which we want to keep.  Lastblock is -1 when
         * the file is truncated to 0.
         */
        /* Avoid sign overflow - XXX assumes that off_t is a quad_t. */
        if (length > QUAD_MAX - fs->lfs_bsize)
                lastblock = lblkno(fs, QUAD_MAX - fs->lfs_bsize);
        else
                lastblock = lblkno(fs, length + fs->lfs_bsize - 1) - 1;
        lastiblock[SINGLE] = lastblock - NDADDR;
        lastiblock[DOUBLE] = lastiblock[SINGLE] - NINDIR(fs);
        lastiblock[TRIPLE] = lastiblock[DOUBLE] - NINDIR(fs) * NINDIR(fs);
        nblocks = btofsb(fs, fs->lfs_bsize);
        /*
         * Record changed file and block pointers before we start
         * freeing blocks.  lastiblock values are also normalized to -1
         * for calls to lfs_indirtrunc below.
         */
        memcpy((void *)newblks, (void *)&oip->i_ffs1_db[0], sizeof newblks);
        for (level = TRIPLE; level >= SINGLE; level--)
                if (lastiblock[level] < 0) {
                        newblks[NDADDR+level] = 0;
                        lastiblock[level] = -1;
                }
        for (i = NDADDR - 1; i > lastblock; i--)
                newblks[i] = 0;

        oip->i_size = oip->i_ffs1_size = osize;
        error = lfs_vtruncbuf(ovp, lastblock + 1, false, 0);
        if (error && !allerror)
                allerror = error;

        /*
         * Indirect blocks first.
         */
        indir_lbn[SINGLE] = -NDADDR;
        indir_lbn[DOUBLE] = indir_lbn[SINGLE] - NINDIR(fs) - 1;
        indir_lbn[TRIPLE] = indir_lbn[DOUBLE] - NINDIR(fs) * NINDIR(fs) - 1;
        for (level = TRIPLE; level >= SINGLE; level--) {
                bn = oip->i_ffs1_ib[level];
                if (bn != 0) {
                        error = lfs_indirtrunc(oip, indir_lbn[level],
                                               bn, lastiblock[level],
                                               level, &count, &rcount,
                                               &lastseg, &bc);
                        if (error)
                                allerror = error;
                        real_released += rcount;
                        blocksreleased += count;
                        if (lastiblock[level] < 0) {
                                if (oip->i_ffs1_ib[level] > 0)
                                        real_released += nblocks;
                                blocksreleased += nblocks;
                                oip->i_ffs1_ib[level] = 0;
                                lfs_blkfree(fs, oip, bn, fs->lfs_bsize,
                                            &lastseg, &bc);
                                lfs_deregister_block(ovp, bn);
                        }
                }
                if (lastiblock[level] >= 0)
                        goto done;
        }

        /*
         * All whole direct blocks or frags.
         */
        for (i = NDADDR - 1; i > lastblock; i--) {
                long bsize, obsize;

                bn = oip->i_ffs1_db[i];
                if (bn == 0)
                        continue;
                bsize = blksize(fs, oip, i);
                if (oip->i_ffs1_db[i] > 0) {
                        /* Check for fragment size changes */
                        obsize = oip->i_lfs_fragsize[i];
                        real_released += btofsb(fs, obsize);
                        oip->i_lfs_fragsize[i] = 0;
                } else
                        obsize = 0;
                blocksreleased += btofsb(fs, bsize);
                oip->i_ffs1_db[i] = 0;
                lfs_blkfree(fs, oip, bn, obsize, &lastseg, &bc);
                lfs_deregister_block(ovp, bn);
        }
        if (lastblock < 0)
                goto done;

        /*
         * Finally, look for a change in size of the
         * last direct block; release any frags.
         */
        bn = oip->i_ffs1_db[lastblock];
        if (bn != 0) {
                long oldspace, newspace;
#if 0
                long olddspace;
#endif

                /*
                 * Calculate amount of space we're giving
                 * back as old block size minus new block size.
                 */
                oldspace = blksize(fs, oip, lastblock);
#if 0
                olddspace = oip->i_lfs_fragsize[lastblock];
#endif

                oip->i_size = oip->i_ffs1_size = length;
                newspace = blksize(fs, oip, lastblock);
                if (newspace == 0)
                        panic("itrunc: newspace");
                if (oldspace - newspace > 0) {
                        blocksreleased += btofsb(fs, oldspace - newspace);
                }
#if 0
                if (bn > 0 && olddspace - newspace > 0) {
                        /* No segment accounting here, just vnode */
                        real_released += btofsb(fs, olddspace - newspace);
                }
#endif
        }

done:
        /* Finish segment accounting corrections */
        lfs_update_seguse(fs, oip, lastseg, bc);
#ifdef DIAGNOSTIC
        for (level = SINGLE; level <= TRIPLE; level++)
                if ((newblks[NDADDR + level] == 0) !=
                    ((oip->i_ffs1_ib[level]) == 0)) {
                        panic("lfs itrunc1");
                }
        for (i = 0; i < NDADDR; i++)
                if ((newblks[i] == 0) != (oip->i_ffs1_db[i] == 0)) {
                        panic("lfs itrunc2");
                }
        if (length == 0 &&
            (!LIST_EMPTY(&ovp->v_cleanblkhd) || !LIST_EMPTY(&ovp->v_dirtyblkhd)))
                panic("lfs itrunc3");
#endif /* DIAGNOSTIC */
        /*
         * Put back the real size.
         */
        oip->i_size = oip->i_ffs1_size = length;
        oip->i_lfs_effnblks -= blocksreleased;
        oip->i_ffs1_blocks -= real_released;
        mutex_enter(&lfs_lock);
        fs->lfs_bfree += blocksreleased;
        mutex_exit(&lfs_lock);
#ifdef DIAGNOSTIC
        if (oip->i_size == 0 &&
            (oip->i_ffs1_blocks != 0 || oip->i_lfs_effnblks != 0)) {
                printf("lfs_truncate: truncate to 0 but %d blks/%d effblks\n",
                       oip->i_ffs1_blocks, oip->i_lfs_effnblks);
                panic("lfs_truncate: persistent blocks");
        }
#endif

        /*
         * If we truncated to zero, take us off the paging queue.
         */
        mutex_enter(&lfs_lock);
        if (oip->i_size == 0 && oip->i_flags & IN_PAGING) {
                oip->i_flags &= ~IN_PAGING;
                TAILQ_REMOVE(&fs->lfs_pchainhd, oip, i_lfs_pchain);
        }
        mutex_exit(&lfs_lock);

        oip->i_flag |= IN_CHANGE;
#ifdef QUOTA
        (void) chkdq(oip, -blocksreleased, NOCRED, 0);
#endif
        lfs_reserve(fs, ovp, NULL,
            -btofsb(fs, (2 * NIADDR + 3) << fs->lfs_bshift));
        genfs_node_unlock(ovp);
  errout:
        oip->i_lfs_hiblk = lblkno(fs, oip->i_size + fs->lfs_bsize - 1) - 1;
        if (ovp != fs->lfs_ivnode)
                lfs_segunlock(fs);
        return (allerror ? allerror : error);
}

/* Update segment and avail usage information when removing a block. */
static int
lfs_blkfree(struct lfs *fs, struct inode *ip, daddr_t daddr,
            size_t bsize, long *lastseg, size_t *num)
{
        long seg;
        int error = 0;

        ASSERT_SEGLOCK(fs);
        bsize = fragroundup(fs, bsize);
        if (daddr > 0) {
                if (*lastseg != (seg = dtosn(fs, daddr))) {
                        error = lfs_update_seguse(fs, ip, *lastseg, *num);
                        *num = bsize;
                        *lastseg = seg;
                } else
                        *num += bsize;
        }

        return error;
}

/* Finish the accounting updates for a segment. */
static int
lfs_update_seguse(struct lfs *fs, struct inode *ip, long lastseg, size_t num)
{
        struct segdelta *sd;
        struct vnode *vp;

        ASSERT_SEGLOCK(fs);
        if (lastseg < 0 || num == 0)
                return 0;

        vp = ITOV(ip);
        LIST_FOREACH(sd, &ip->i_lfs_segdhd, list)
                if (sd->segnum == lastseg)
                        break;
        if (sd == NULL) {
                sd = malloc(sizeof(*sd), M_SEGMENT, M_WAITOK);
                sd->segnum = lastseg;
                sd->num = 0;
                LIST_INSERT_HEAD(&ip->i_lfs_segdhd, sd, list);
        }
        sd->num += num;

        return 0;
}

static void
lfs_finalize_seguse(struct lfs *fs, void *v)
{
        SEGUSE *sup;
        struct buf *bp;
        struct segdelta *sd;
        LIST_HEAD(, segdelta) *hd = v;

        ASSERT_SEGLOCK(fs);
        while((sd = LIST_FIRST(hd)) != NULL) {
                LIST_REMOVE(sd, list);
                LFS_SEGENTRY(sup, fs, sd->segnum, bp);
                if (sd->num > sup->su_nbytes) {
                        printf("lfs_finalize_seguse: segment %ld short by %ld\n",
                                sd->segnum, (long)(sd->num - sup->su_nbytes));
                        panic("lfs_finalize_seguse: negative bytes");
                        sup->su_nbytes = sd->num;
                }
                sup->su_nbytes -= sd->num;
                LFS_WRITESEGENTRY(sup, fs, sd->segnum, bp);
                free(sd, M_SEGMENT);
        }
}

/* Finish the accounting updates for a segment. */
void
lfs_finalize_ino_seguse(struct lfs *fs, struct inode *ip)
{
        ASSERT_SEGLOCK(fs);
        lfs_finalize_seguse(fs, &ip->i_lfs_segdhd);
}

/* Finish the accounting updates for a segment. */
void
lfs_finalize_fs_seguse(struct lfs *fs)
{
        ASSERT_SEGLOCK(fs);
        lfs_finalize_seguse(fs, &fs->lfs_segdhd);
}

/*
 * Release blocks associated with the inode ip and stored in the indirect
 * block bn.  Blocks are free'd in LIFO order up to (but not including)
 * lastbn.  If level is greater than SINGLE, the block is an indirect block
 * and recursive calls to indirtrunc must be used to cleanse other indirect
 * blocks.
 *
 * NB: triple indirect blocks are untested.
 */
static int
lfs_indirtrunc(struct inode *ip, daddr_t lbn, daddr_t dbn,
               daddr_t lastbn, int level, long *countp,
               long *rcountp, long *lastsegp, size_t *bcp)
{
        int i;
        struct buf *bp;
        struct lfs *fs = ip->i_lfs;
        int32_t *bap;   /* XXX ondisk32 */
        struct vnode *vp;
        daddr_t nb, nlbn, last;
        int32_t *copy = NULL;   /* XXX ondisk32 */
        long blkcount, rblkcount, factor;
        int nblocks, blocksreleased = 0, real_released = 0;
        int error = 0, allerror = 0;

        ASSERT_SEGLOCK(fs);
        /*
         * Calculate index in current block of last
         * block to be kept.  -1 indicates the entire
         * block so we need not calculate the index.
         */
        factor = 1;
        for (i = SINGLE; i < level; i++)
                factor *= NINDIR(fs);
        last = lastbn;
        if (lastbn > 0)
                last /= factor;
        nblocks = btofsb(fs, fs->lfs_bsize);
        /*
         * Get buffer of block pointers, zero those entries corresponding
         * to blocks to be free'd, and update on disk copy first.  Since
         * double(triple) indirect before single(double) indirect, calls
         * to bmap on these blocks will fail.  However, we already have
         * the on disk address, so we have to set the b_blkno field
         * explicitly instead of letting bread do everything for us.
         */
        vp = ITOV(ip);
        bp = getblk(vp, lbn, (int)fs->lfs_bsize, 0, 0);
        if (bp->b_oflags & (BO_DONE | BO_DELWRI)) {
                /* Braces must be here in case trace evaluates to nothing. */
                trace(TR_BREADHIT, pack(vp, fs->lfs_bsize), lbn);
        } else {
                trace(TR_BREADMISS, pack(vp, fs->lfs_bsize), lbn);
                curlwp->l_ru.ru_inblock++; /* pay for read */
                bp->b_flags |= B_READ;
                if (bp->b_bcount > bp->b_bufsize)
                        panic("lfs_indirtrunc: bad buffer size");
                bp->b_blkno = fsbtodb(fs, dbn);
                VOP_STRATEGY(vp, bp);
                error = biowait(bp);
        }
        if (error) {
                brelse(bp, 0);
                *countp = *rcountp = 0;
                return (error);
        }

        bap = (int32_t *)bp->b_data;    /* XXX ondisk32 */
        if (lastbn >= 0) {
                copy = (int32_t *)lfs_malloc(fs, fs->lfs_bsize, LFS_NB_IBLOCK);
                memcpy((void *)copy, (void *)bap, (u_int)fs->lfs_bsize);
                memset((void *)&bap[last + 1], 0,
                /* XXX ondisk32 */
                  (u_int)(NINDIR(fs) - (last + 1)) * sizeof (int32_t));
                error = VOP_BWRITE(bp->b_vp, bp);
                if (error)
                        allerror = error;
                bap = copy;
        }

        /*
         * Recursively free totally unused blocks.
         */
        for (i = NINDIR(fs) - 1, nlbn = lbn + 1 - i * factor; i > last;
            i--, nlbn += factor) {
                nb = bap[i];
                if (nb == 0)
                        continue;
                if (level > SINGLE) {
                        error = lfs_indirtrunc(ip, nlbn, nb,
                                               (daddr_t)-1, level - 1,
                                               &blkcount, &rblkcount,
                                               lastsegp, bcp);
                        if (error)
                                allerror = error;
                        blocksreleased += blkcount;
                        real_released += rblkcount;
                }
                lfs_blkfree(fs, ip, nb, fs->lfs_bsize, lastsegp, bcp);
                if (bap[i] > 0)
                        real_released += nblocks;
                blocksreleased += nblocks;
        }

        /*
         * Recursively free last partial block.
         */
        if (level > SINGLE && lastbn >= 0) {
                last = lastbn % factor;
                nb = bap[i];
                if (nb != 0) {
                        error = lfs_indirtrunc(ip, nlbn, nb,
                                               last, level - 1, &blkcount,
                                               &rblkcount, lastsegp, bcp);
                        if (error)
                                allerror = error;
                        real_released += rblkcount;
                        blocksreleased += blkcount;
                }
        }

        if (copy != NULL) {
                lfs_free(fs, copy, LFS_NB_IBLOCK);
        } else {
                mutex_enter(&bufcache_lock);
                if (bp->b_oflags & BO_DELWRI) {
                        LFS_UNLOCK_BUF(bp);
                        fs->lfs_avail += btofsb(fs, bp->b_bcount);
                        wakeup(&fs->lfs_avail);
                }
                brelsel(bp, BC_INVAL);
                mutex_exit(&bufcache_lock);
        }

        *countp = blocksreleased;
        *rcountp = real_released;
        return (allerror);
}

/*
 * Destroy any in core blocks past the truncation length.
 * Inlined from vtruncbuf, so that lfs_avail could be updated.
 * We take the seglock to prevent cleaning from occurring while we are
 * invalidating blocks.
 */
static int
lfs_vtruncbuf(struct vnode *vp, daddr_t lbn, bool catch, int slptimeo)
{
        struct buf *bp, *nbp;
        int error;
        struct lfs *fs;
        voff_t off;

        off = round_page((voff_t)lbn << vp->v_mount->mnt_fs_bshift);
        mutex_enter(vp->v_interlock);
        error = VOP_PUTPAGES(vp, off, 0, PGO_FREE | PGO_SYNCIO);
        if (error)
                return error;

        fs = VTOI(vp)->i_lfs;

        ASSERT_SEGLOCK(fs);

        mutex_enter(&bufcache_lock);
restart:        
        for (bp = LIST_FIRST(&vp->v_cleanblkhd); bp; bp = nbp) {
                nbp = LIST_NEXT(bp, b_vnbufs);
                if (bp->b_lblkno < lbn)
                        continue;
                error = bbusy(bp, catch, slptimeo, NULL);
                if (error == EPASSTHROUGH)
                        goto restart;
                if (error != 0) {
                        mutex_exit(&bufcache_lock);
                        return (error);
                }
                mutex_enter(bp->b_objlock);
                if (bp->b_oflags & BO_DELWRI) {
                        bp->b_oflags &= ~BO_DELWRI;
                        fs->lfs_avail += btofsb(fs, bp->b_bcount);
                        wakeup(&fs->lfs_avail);
                }
                mutex_exit(bp->b_objlock);
                LFS_UNLOCK_BUF(bp);
                brelsel(bp, BC_INVAL | BC_VFLUSH);
        }

        for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                nbp = LIST_NEXT(bp, b_vnbufs);
                if (bp->b_lblkno < lbn)
                        continue;
                error = bbusy(bp, catch, slptimeo, NULL);
                if (error == EPASSTHROUGH)
                        goto restart;
                if (error != 0) {
                        mutex_exit(&bufcache_lock);
                        return (error);
                }
                mutex_enter(bp->b_objlock);
                if (bp->b_oflags & BO_DELWRI) {
                        bp->b_oflags &= ~BO_DELWRI;
                        fs->lfs_avail += btofsb(fs, bp->b_bcount);
                        wakeup(&fs->lfs_avail);
                }
                mutex_exit(bp->b_objlock);
                LFS_UNLOCK_BUF(bp);
                brelsel(bp, BC_INVAL | BC_VFLUSH);
        }
        mutex_exit(&bufcache_lock);

        return (0);
}