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

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

/*      $NetBSD: lfs_balloc.c,v 1.70 2011/07/11 08:27:40 hannken 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) 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_balloc.c        8.4 (Berkeley) 5/8/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: lfs_balloc.c,v 1.70 2011/07/11 08:27:40 hannken Exp $");

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

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

#include <miscfs/specfs/specdev.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>

#include <uvm/uvm.h>

int lfs_fragextend(struct vnode *, int, int, daddr_t, struct buf **, kauth_cred_t);

u_int64_t locked_fakequeue_count;

/*
 * Allocate a block, and to inode and filesystem block accounting for it
 * and for any indirect blocks the may need to be created in order for
 * this block to be created.
 *
 * Blocks which have never been accounted for (i.e., which "do not exist")
 * have disk address 0, which is translated by ufs_bmap to the special value
 * UNASSIGNED == -1, as in the historical UFS.
 *
 * Blocks which have been accounted for but which have not yet been written
 * to disk are given the new special disk address UNWRITTEN == -2, so that
 * they can be differentiated from completely new blocks.
 */
/* VOP_BWRITE NIADDR+2 times */
int
lfs_balloc(struct vnode *vp, off_t startoffset, int iosize, kauth_cred_t cred,
    int flags, struct buf **bpp)
{
        int offset;
        daddr_t daddr, idaddr;
        struct buf *ibp, *bp;
        struct inode *ip;
        struct lfs *fs;
        struct indir indirs[NIADDR+2], *idp;
        daddr_t lbn, lastblock;
        int bcount;
        int error, frags, i, nsize, osize, num;

        ip = VTOI(vp);
        fs = ip->i_lfs;
        offset = blkoff(fs, startoffset);
        KASSERT(iosize <= fs->lfs_bsize);
        lbn = lblkno(fs, startoffset);
        /* (void)lfs_check(vp, lbn, 0); */

        ASSERT_MAYBE_SEGLOCK(fs);

        /*
         * Three cases: it's a block beyond the end of file, it's a block in
         * the file that may or may not have been assigned a disk address or
         * we're writing an entire block.
         *
         * Note, if the daddr is UNWRITTEN, the block already exists in
         * the cache (it was read or written earlier).  If so, make sure
         * we don't count it as a new block or zero out its contents. If
         * it did not, make sure we allocate any necessary indirect
         * blocks.
         *
         * If we are writing a block beyond the end of the file, we need to
         * check if the old last block was a fragment.  If it was, we need
         * to rewrite it.
         */

        if (bpp)
                *bpp = NULL;

        /* Check for block beyond end of file and fragment extension needed. */
        lastblock = lblkno(fs, ip->i_size);
        if (lastblock < NDADDR && lastblock < lbn) {
                osize = blksize(fs, ip, lastblock);
                if (osize < fs->lfs_bsize && osize > 0) {
                        if ((error = lfs_fragextend(vp, osize, fs->lfs_bsize,
                                                    lastblock,
                                                    (bpp ? &bp : NULL), cred)))
                                return (error);
                        ip->i_ffs1_size = ip->i_size =
                            (lastblock + 1) * fs->lfs_bsize;
                        uvm_vnp_setsize(vp, ip->i_size);
                        ip->i_flag |= IN_CHANGE | IN_UPDATE;
                        if (bpp)
                                (void) VOP_BWRITE(bp->b_vp, bp);
                }
        }

        /*
         * If the block we are writing is a direct block, it's the last
         * block in the file, and offset + iosize is less than a full
         * block, we can write one or more fragments.  There are two cases:
         * the block is brand new and we should allocate it the correct
         * size or it already exists and contains some fragments and
         * may need to extend it.
         */
        if (lbn < NDADDR && lblkno(fs, ip->i_size) <= lbn) {
                osize = blksize(fs, ip, lbn);
                nsize = fragroundup(fs, offset + iosize);
                if (lblktosize(fs, lbn) >= ip->i_size) {
                        /* Brand new block or fragment */
                        frags = numfrags(fs, nsize);
                        if (!ISSPACE(fs, frags, cred))
                                return ENOSPC;
                        if (bpp) {
                                *bpp = bp = getblk(vp, lbn, nsize, 0, 0);
                                bp->b_blkno = UNWRITTEN;
                                if (flags & B_CLRBUF)
                                        clrbuf(bp);
                        }
                        ip->i_lfs_effnblks += frags;
                        mutex_enter(&lfs_lock);
                        fs->lfs_bfree -= frags;
                        mutex_exit(&lfs_lock);
                        ip->i_ffs1_db[lbn] = UNWRITTEN;
                } else {
                        if (nsize <= osize) {
                                /* No need to extend */
                                if (bpp && (error = bread(vp, lbn, osize,
                                    NOCRED, 0, &bp)))
                                        return error;
                        } else {
                                /* Extend existing block */
                                if ((error =
                                     lfs_fragextend(vp, osize, nsize, lbn,
                                                    (bpp ? &bp : NULL), cred)))
                                        return error;
                        }
                        if (bpp)
                                *bpp = bp;
                }
                return 0;
        }

        error = ufs_bmaparray(vp, lbn, &daddr, &indirs[0], &num, NULL, NULL);
        if (error)
                return (error);

        daddr = (daddr_t)((int32_t)daddr); /* XXX ondisk32 */
        KASSERT(daddr <= LFS_MAX_DADDR);

        /*
         * Do byte accounting all at once, so we can gracefully fail *before*
         * we start assigning blocks.
         */
        frags = VFSTOUFS(vp->v_mount)->um_seqinc;
        bcount = 0;
        if (daddr == UNASSIGNED) {
                bcount = frags;
        }
        for (i = 1; i < num; ++i) {
                if (!indirs[i].in_exists) {
                        bcount += frags;
                }
        }
        if (ISSPACE(fs, bcount, cred)) {
                mutex_enter(&lfs_lock);
                fs->lfs_bfree -= bcount;
                mutex_exit(&lfs_lock);
                ip->i_lfs_effnblks += bcount;
        } else {
                return ENOSPC;
        }

        if (daddr == UNASSIGNED) {
                if (num > 0 && ip->i_ffs1_ib[indirs[0].in_off] == 0) {
                        ip->i_ffs1_ib[indirs[0].in_off] = UNWRITTEN;
                }

                /*
                 * Create new indirect blocks if necessary
                 */
                if (num > 1) {
                        idaddr = ip->i_ffs1_ib[indirs[0].in_off];
                        for (i = 1; i < num; ++i) {
                                ibp = getblk(vp, indirs[i].in_lbn,
                                    fs->lfs_bsize, 0,0);
                                if (!indirs[i].in_exists) {
                                        clrbuf(ibp);
                                        ibp->b_blkno = UNWRITTEN;
                                } else if (!(ibp->b_oflags & (BO_DELWRI | BO_DONE))) {
                                        ibp->b_blkno = fsbtodb(fs, idaddr);
                                        ibp->b_flags |= B_READ;
                                        VOP_STRATEGY(vp, ibp);
                                        biowait(ibp);
                                }
                                /*
                                 * This block exists, but the next one may not.
                                 * If that is the case mark it UNWRITTEN to keep
                                 * the accounting straight.
                                 */
                                /* XXX ondisk32 */
                                if (((int32_t *)ibp->b_data)[indirs[i].in_off] == 0)
                                        ((int32_t *)ibp->b_data)[indirs[i].in_off] =
                                                UNWRITTEN;
                                /* XXX ondisk32 */
                                idaddr = ((int32_t *)ibp->b_data)[indirs[i].in_off];
#ifdef DEBUG
                                if (vp == fs->lfs_ivnode) {
                                        LFS_ENTER_LOG("balloc", __FILE__,
                                                __LINE__, indirs[i].in_lbn,
                                                ibp->b_flags, curproc->p_pid);
                                }
#endif
                                if ((error = VOP_BWRITE(ibp->b_vp, ibp)))
                                        return error;
                        }
                }
        }


        /*
         * Get the existing block from the cache, if requested.
         */
        if (bpp)
                *bpp = bp = getblk(vp, lbn, blksize(fs, ip, lbn), 0, 0);

        /*
         * Do accounting on blocks that represent pages.
         */
        if (!bpp)
                lfs_register_block(vp, lbn);

        /*
         * The block we are writing may be a brand new block
         * in which case we need to do accounting.
         *
         * We can tell a truly new block because ufs_bmaparray will say
         * it is UNASSIGNED.  Once we allocate it we will assign it the
         * disk address UNWRITTEN.
         */
        if (daddr == UNASSIGNED) {
                if (bpp) {
                        if (flags & B_CLRBUF)
                                clrbuf(bp);

                        /* Note the new address */
                        bp->b_blkno = UNWRITTEN;
                }

                switch (num) {
                    case 0:
                        ip->i_ffs1_db[lbn] = UNWRITTEN;
                        break;
                    case 1:
                        ip->i_ffs1_ib[indirs[0].in_off] = UNWRITTEN;
                        break;
                    default:
                        idp = &indirs[num - 1];
                        if (bread(vp, idp->in_lbn, fs->lfs_bsize, NOCRED,
                                  B_MODIFY, &ibp))
                                panic("lfs_balloc: bread bno %lld",
                                    (long long)idp->in_lbn);
                        /* XXX ondisk32 */
                        ((int32_t *)ibp->b_data)[idp->in_off] = UNWRITTEN;
#ifdef DEBUG
                        if (vp == fs->lfs_ivnode) {
                                LFS_ENTER_LOG("balloc", __FILE__,
                                        __LINE__, idp->in_lbn,
                                        ibp->b_flags, curproc->p_pid);
                        }
#endif
                        VOP_BWRITE(ibp->b_vp, ibp);
                }
        } else if (bpp && !(bp->b_oflags & (BO_DONE|BO_DELWRI))) {
                /*
                 * Not a brand new block, also not in the cache;
                 * read it in from disk.
                 */
                if (iosize == fs->lfs_bsize)
                        /* Optimization: I/O is unnecessary. */
                        bp->b_blkno = daddr;
                else {
                        /*
                         * We need to read the block to preserve the
                         * existing bytes.
                         */
                        bp->b_blkno = daddr;
                        bp->b_flags |= B_READ;
                        VOP_STRATEGY(vp, bp);
                        return (biowait(bp));
                }
        }

        return (0);
}

/* VOP_BWRITE 1 time */
int
lfs_fragextend(struct vnode *vp, int osize, int nsize, daddr_t lbn, struct buf **bpp,
    kauth_cred_t cred)
{
        struct inode *ip;
        struct lfs *fs;
        long frags;
        int error;
        extern long locked_queue_bytes;
        size_t obufsize;

        ip = VTOI(vp);
        fs = ip->i_lfs;
        frags = (long)numfrags(fs, nsize - osize);
        error = 0;

        ASSERT_NO_SEGLOCK(fs);

        /*
         * Get the seglock so we don't enlarge blocks while a segment
         * is being written.  If we're called with bpp==NULL, though,
         * we are only pretending to change a buffer, so we don't have to
         * lock.
         */
    top:
        if (bpp) {
                rw_enter(&fs->lfs_fraglock, RW_READER);
                LFS_DEBUG_COUNTLOCKED("frag");
        }

        if (!ISSPACE(fs, frags, cred)) {
                error = ENOSPC;
                goto out;
        }

        /*
         * If we are not asked to actually return the block, all we need
         * to do is allocate space for it.  UBC will handle dirtying the
         * appropriate things and making sure it all goes to disk.
         * Don't bother to read in that case.
         */
        if (bpp && (error = bread(vp, lbn, osize, NOCRED, 0, bpp))) {
                brelse(*bpp, 0);
                goto out;
        }
#ifdef QUOTA
        if ((error = chkdq(ip, frags, cred, 0))) {
                if (bpp)
                        brelse(*bpp, 0);
                goto out;
        }
#endif
        /*
         * Adjust accounting for lfs_avail.  If there's not enough room,
         * we will have to wait for the cleaner, which we can't do while
         * holding a block busy or while holding the seglock.  In that case,
         * release both and start over after waiting.
         */

        if (bpp && ((*bpp)->b_oflags & BO_DELWRI)) {
                if (!lfs_fits(fs, frags)) {
                        if (bpp)
                                brelse(*bpp, 0);
#ifdef QUOTA
                        chkdq(ip, -frags, cred, 0);
#endif
                        rw_exit(&fs->lfs_fraglock);
                        lfs_availwait(fs, frags);
                        goto top;
                }
                fs->lfs_avail -= frags;
        }

        mutex_enter(&lfs_lock);
        fs->lfs_bfree -= frags;
        mutex_exit(&lfs_lock);
        ip->i_lfs_effnblks += frags;
        ip->i_flag |= IN_CHANGE | IN_UPDATE;

        if (bpp) {
                obufsize = (*bpp)->b_bufsize;
                allocbuf(*bpp, nsize, 1);

                /* Adjust locked-list accounting */
                if (((*bpp)->b_flags & B_LOCKED) != 0 &&
                    (*bpp)->b_iodone == NULL) {
                        mutex_enter(&lfs_lock);
                        locked_queue_bytes += (*bpp)->b_bufsize - obufsize;
                        mutex_exit(&lfs_lock);
                }

                memset((char *)((*bpp)->b_data) + osize, 0, (u_int)(nsize - osize));
        }

    out:
        if (bpp) {
                rw_exit(&fs->lfs_fraglock);
        }
        return (error);
}

static inline int
lge(struct lbnentry *a, struct lbnentry *b)
{
        return a->lbn - b->lbn;
}

SPLAY_PROTOTYPE(lfs_splay, lbnentry, entry, lge);

SPLAY_GENERATE(lfs_splay, lbnentry, entry, lge);

/*
 * Record this lbn as being "write pending".  We used to have this information
 * on the buffer headers, but since pages don't have buffer headers we
 * record it here instead.
 */
void
lfs_register_block(struct vnode *vp, daddr_t lbn)
{
        struct lfs *fs;
        struct inode *ip;
        struct lbnentry *lbp;

        ip = VTOI(vp);

        /* Don't count metadata */
        if (lbn < 0 || vp->v_type != VREG || ip->i_number == LFS_IFILE_INUM)
                return;

        fs = ip->i_lfs;

        ASSERT_NO_SEGLOCK(fs);

        /* If no space, wait for the cleaner */
        lfs_availwait(fs, btofsb(fs, 1 << fs->lfs_bshift));

        lbp = (struct lbnentry *)pool_get(&lfs_lbnentry_pool, PR_WAITOK);
        lbp->lbn = lbn;
        mutex_enter(&lfs_lock);
        if (SPLAY_INSERT(lfs_splay, &ip->i_lfs_lbtree, lbp) != NULL) {
                mutex_exit(&lfs_lock);
                /* Already there */
                pool_put(&lfs_lbnentry_pool, lbp);
                return;
        }

        ++ip->i_lfs_nbtree;
        fs->lfs_favail += btofsb(fs, (1 << fs->lfs_bshift));
        fs->lfs_pages += fs->lfs_bsize >> PAGE_SHIFT;
        ++locked_fakequeue_count;
        lfs_subsys_pages += fs->lfs_bsize >> PAGE_SHIFT;
        mutex_exit(&lfs_lock);
}

static void
lfs_do_deregister(struct lfs *fs, struct inode *ip, struct lbnentry *lbp)
{
        ASSERT_MAYBE_SEGLOCK(fs);

        mutex_enter(&lfs_lock);
        --ip->i_lfs_nbtree;
        SPLAY_REMOVE(lfs_splay, &ip->i_lfs_lbtree, lbp);
        if (fs->lfs_favail > btofsb(fs, (1 << fs->lfs_bshift)))
                fs->lfs_favail -= btofsb(fs, (1 << fs->lfs_bshift));
        fs->lfs_pages -= fs->lfs_bsize >> PAGE_SHIFT;
        if (locked_fakequeue_count > 0)
                --locked_fakequeue_count;
        lfs_subsys_pages -= fs->lfs_bsize >> PAGE_SHIFT;
        mutex_exit(&lfs_lock);

        pool_put(&lfs_lbnentry_pool, lbp);
}

void
lfs_deregister_block(struct vnode *vp, daddr_t lbn)
{
        struct lfs *fs;
        struct inode *ip;
        struct lbnentry *lbp;
        struct lbnentry tmp;

        ip = VTOI(vp);

        /* Don't count metadata */
        if (lbn < 0 || vp->v_type != VREG || ip->i_number == LFS_IFILE_INUM)
                return;

        fs = ip->i_lfs;
        tmp.lbn = lbn;
        lbp = SPLAY_FIND(lfs_splay, &ip->i_lfs_lbtree, &tmp);
        if (lbp == NULL)
                return;

        lfs_do_deregister(fs, ip, lbp);
}

void
lfs_deregister_all(struct vnode *vp)
{
        struct lbnentry *lbp, *nlbp;
        struct lfs_splay *hd;
        struct lfs *fs;
        struct inode *ip;

        ip = VTOI(vp);
        fs = ip->i_lfs;
        hd = &ip->i_lfs_lbtree;

        for (lbp = SPLAY_MIN(lfs_splay, hd); lbp != NULL; lbp = nlbp) {
                nlbp = SPLAY_NEXT(lfs_splay, hd, lbp);
                lfs_do_deregister(fs, ip, lbp);
        }
}