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

[minix.git] / sys / ufs / ext2fs / ext2fs_alloc.c

/*      $NetBSD: ext2fs_alloc.c,v 1.42 2011/03/06 04:46:26 rmind Exp $  */

/*
 * 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 8.11 (Berkeley) 10/27/94
 *  Modified for ext2fs by Manuel Bouyer.
 */

/*
 * Copyright (c) 1997 Manuel Bouyer.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *      @(#)ffs_alloc.c 8.11 (Berkeley) 10/27/94
 *  Modified for ext2fs by Manuel Bouyer.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ext2fs_alloc.c,v 1.42 2011/03/06 04:46:26 rmind Exp $");

#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/kernel.h>
#include <sys/syslog.h>
#include <sys/kauth.h>

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

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

u_long ext2gennumber;

static daddr_t  ext2fs_alloccg(struct inode *, int, daddr_t, int);
static u_long   ext2fs_dirpref(struct m_ext2fs *);
static void     ext2fs_fserr(struct m_ext2fs *, u_int, const char *);
static u_long   ext2fs_hashalloc(struct inode *, int, long, int,
                    daddr_t (*)(struct inode *, int, daddr_t, int));
static daddr_t  ext2fs_nodealloccg(struct inode *, int, daddr_t, int);
static daddr_t  ext2fs_mapsearch(struct m_ext2fs *, char *, daddr_t);

/*
 * Allocate a block in the file system.
 *
 * 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) quadradically 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) quadradically rehash into other cylinder groups, until an
 *        available block is located.
 */
int
ext2fs_alloc(struct inode *ip, daddr_t lbn, daddr_t bpref,
    kauth_cred_t cred, daddr_t *bnp)
{
        struct m_ext2fs *fs;
        daddr_t bno;
        int cg;

        *bnp = 0;
        fs = ip->i_e2fs;
#ifdef DIAGNOSTIC
        if (cred == NOCRED)
                panic("ext2fs_alloc: missing credential");
#endif /* DIAGNOSTIC */
        if (fs->e2fs.e2fs_fbcount == 0)
                goto nospace;
        if (kauth_authorize_system(cred, KAUTH_SYSTEM_FS_RESERVEDSPACE, 0, NULL,
            NULL, NULL) != 0 &&
            freespace(fs) <= 0)
                goto nospace;
        if (bpref >= fs->e2fs.e2fs_bcount)
                bpref = 0;
        if (bpref == 0)
                cg = ino_to_cg(fs, ip->i_number);
        else
                cg = dtog(fs, bpref);
        bno = (daddr_t)ext2fs_hashalloc(ip, cg, bpref, fs->e2fs_bsize,
            ext2fs_alloccg);
        if (bno > 0) {
                ip->i_e2fs_nblock += btodb(fs->e2fs_bsize);
                ip->i_flag |= IN_CHANGE | IN_UPDATE;
                *bnp = bno;
                return (0);
        }
nospace:
        ext2fs_fserr(fs, kauth_cred_geteuid(cred), "file system full");
        uprintf("\n%s: write failed, file system is full\n", fs->e2fs_fsmnt);
        return (ENOSPC);
}

/*
 * Allocate an inode in the file system.
 *
 * If allocating a directory, use ext2fs_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) quadradically 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) quadradically rehash into other cylinder groups, until an
 *        available inode is located.
 */
int
ext2fs_valloc(struct vnode *pvp, int mode, kauth_cred_t cred,
    struct vnode **vpp)
{
        struct inode *pip;
        struct m_ext2fs *fs;
        struct inode *ip;
        ino_t ino, ipref;
        int cg, error;

        *vpp = NULL;
        pip = VTOI(pvp);
        fs = pip->i_e2fs;
        if (fs->e2fs.e2fs_ficount == 0)
                goto noinodes;

        if ((mode & IFMT) == IFDIR)
                cg = ext2fs_dirpref(fs);
        else
                cg = ino_to_cg(fs, pip->i_number);
        ipref = cg * fs->e2fs.e2fs_ipg + 1;
        ino = (ino_t)ext2fs_hashalloc(pip, cg, (long)ipref, mode, ext2fs_nodealloccg);
        if (ino == 0)
                goto noinodes;
        error = VFS_VGET(pvp->v_mount, ino, vpp);
        if (error) {
                ext2fs_vfree(pvp, ino, mode);
                return (error);
        }
        ip = VTOI(*vpp);
        if (ip->i_e2fs_mode && ip->i_e2fs_nlink != 0) {
                printf("mode = 0%o, nlinks %d, inum = %llu, fs = %s\n",
                    ip->i_e2fs_mode, ip->i_e2fs_nlink,
                    (unsigned long long)ip->i_number, fs->e2fs_fsmnt);
                panic("ext2fs_valloc: dup alloc");
        }

        memset(ip->i_din.e2fs_din, 0, sizeof(struct ext2fs_dinode));

        /*
         * Set up a new generation number for this inode.
         */
        if (++ext2gennumber < time_second)
                ext2gennumber = time_second;
        ip->i_e2fs_gen = ext2gennumber;
        return (0);
noinodes:
        ext2fs_fserr(fs, kauth_cred_geteuid(cred), "out of inodes");
        uprintf("\n%s: create/symlink failed, no inodes free\n", fs->e2fs_fsmnt);
        return (ENOSPC);
}

/*
 * Find a cylinder to place a directory.
 *
 * The policy implemented by this algorithm is to select from
 * among those cylinder groups with above the average number of
 * free inodes, the one with the smallest number of directories.
 */
static u_long
ext2fs_dirpref(struct m_ext2fs *fs)
{
        int cg, maxspace, mincg, avgifree;

        avgifree = fs->e2fs.e2fs_ficount / fs->e2fs_ncg;
        maxspace = 0;
        mincg = -1;
        for (cg = 0; cg < fs->e2fs_ncg; cg++)
                if ( fs->e2fs_gd[cg].ext2bgd_nifree >= avgifree) {
                        if (mincg == -1 || fs->e2fs_gd[cg].ext2bgd_nbfree > maxspace) {
                                mincg = cg;
                                maxspace = fs->e2fs_gd[cg].ext2bgd_nbfree;
                        }
                }
        return mincg;
}

/*
 * 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. Otherwise, the policy is to try to allocate the blocks
 * contigously. The two fields of the ext2 inode extension (see
 * ufs/ufs/inode.h) help this.
 */
daddr_t
ext2fs_blkpref(struct inode *ip, daddr_t lbn, int indx,
                int32_t *bap /* XXX ondisk32 */)
{
        struct m_ext2fs *fs;
        int cg, i;

        fs = ip->i_e2fs;
        /*
         * if we are doing contigous lbn allocation, try to alloc blocks
         * contigously on disk
         */

        if ( ip->i_e2fs_last_blk && lbn == ip->i_e2fs_last_lblk + 1) {
                return ip->i_e2fs_last_blk + 1;
        }

        /*
         * bap, if provided, gives us a list of blocks to which we want to
         * stay close
         */

        if (bap) {
                for (i = indx; i >= 0 ; i--) {
                        if (bap[i]) {
                                return fs2h32(bap[i]) + 1;
                        }
                }
        }

        /* fall back to the first block of the cylinder containing the inode */

        cg = ino_to_cg(fs, ip->i_number);
        return fs->e2fs.e2fs_bpg * cg + fs->e2fs.e2fs_first_dblock + 1;
}

/*
 * Implement the cylinder overflow algorithm.
 *
 * The policy implemented by this algorithm is:
 *   1) allocate the block in its requested cylinder group.
 *   2) quadradically rehash on the cylinder group number.
 *   3) brute force search for a free block.
 */
static u_long
ext2fs_hashalloc(struct inode *ip, int cg, long pref, int size,
                daddr_t (*allocator)(struct inode *, int, daddr_t, int))
{
        struct m_ext2fs *fs;
        long result;
        int i, icg = cg;

        fs = ip->i_e2fs;
        /*
         * 1: preferred cylinder group
         */
        result = (*allocator)(ip, cg, pref, size);
        if (result)
                return (result);
        /*
         * 2: quadratic rehash
         */
        for (i = 1; i < fs->e2fs_ncg; i *= 2) {
                cg += i;
                if (cg >= fs->e2fs_ncg)
                        cg -= fs->e2fs_ncg;
                result = (*allocator)(ip, cg, 0, size);
                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->e2fs_ncg;
        for (i = 2; i < fs->e2fs_ncg; i++) {
                result = (*allocator)(ip, cg, 0, size);
                if (result)
                        return (result);
                cg++;
                if (cg == fs->e2fs_ncg)
                        cg = 0;
        }
        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
ext2fs_alloccg(struct inode *ip, int cg, daddr_t bpref, int size)
{
        struct m_ext2fs *fs;
        char *bbp;
        struct buf *bp;
        /* XXX ondisk32 */
        int error, bno, start, end, loc;

        fs = ip->i_e2fs;
        if (fs->e2fs_gd[cg].ext2bgd_nbfree == 0)
                return (0);
        error = bread(ip->i_devvp, fsbtodb(fs,
                fs->e2fs_gd[cg].ext2bgd_b_bitmap),
                (int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
        if (error) {
                brelse(bp, 0);
                return (0);
        }
        bbp = (char *)bp->b_data;

        if (dtog(fs, bpref) != cg)
                bpref = 0;
        if (bpref != 0) {
                bpref = dtogd(fs, bpref);
                /*
                 * if the requested block is available, use it
                 */
                if (isclr(bbp, bpref)) {
                        bno = bpref;
                        goto gotit;
                }
        }
        /*
         * no blocks in the requested cylinder, so take next
         * available one in this cylinder group.
         * first try to get 8 contigous blocks, then fall back to a single
         * block.
         */
        if (bpref)
                start = dtogd(fs, bpref) / NBBY;
        else
                start = 0;
        end = howmany(fs->e2fs.e2fs_fpg, NBBY) - start;
        for (loc = start; loc < end; loc++) {
                if (bbp[loc] == 0) {
                        bno = loc * NBBY;
                        goto gotit;
                }
        }
        for (loc = 0; loc < start; loc++) {
                if (bbp[loc] == 0) {
                        bno = loc * NBBY;
                        goto gotit;
                }
        }

        bno = ext2fs_mapsearch(fs, bbp, bpref);
        if (bno < 0)
                return (0);
gotit:
#ifdef DIAGNOSTIC
        if (isset(bbp, (daddr_t)bno)) {
                printf("ext2fs_alloccgblk: cg=%d bno=%d fs=%s\n",
                        cg, bno, fs->e2fs_fsmnt);
                panic("ext2fs_alloccg: dup alloc");
        }
#endif
        setbit(bbp, (daddr_t)bno);
        fs->e2fs.e2fs_fbcount--;
        fs->e2fs_gd[cg].ext2bgd_nbfree--;
        fs->e2fs_fmod = 1;
        bdwrite(bp);
        return (cg * fs->e2fs.e2fs_fpg + fs->e2fs.e2fs_first_dblock + bno);
}

/*
 * 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
ext2fs_nodealloccg(struct inode *ip, int cg, daddr_t ipref, int mode)
{
        struct m_ext2fs *fs;
        char *ibp;
        struct buf *bp;
        int error, start, len, loc, map, i;

        ipref--; /* to avoid a lot of (ipref -1) */
        if (ipref == -1)
                ipref = 0;
        fs = ip->i_e2fs;
        if (fs->e2fs_gd[cg].ext2bgd_nifree == 0)
                return (0);
        error = bread(ip->i_devvp, fsbtodb(fs,
                fs->e2fs_gd[cg].ext2bgd_i_bitmap),
                (int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
        if (error) {
                brelse(bp, 0);
                return (0);
        }
        ibp = (char *)bp->b_data;
        if (ipref) {
                ipref %= fs->e2fs.e2fs_ipg;
                if (isclr(ibp, ipref))
                        goto gotit;
        }
        start = ipref / NBBY;
        len = howmany(fs->e2fs.e2fs_ipg - ipref, NBBY);
        loc = skpc(0xff, len, &ibp[start]);
        if (loc == 0) {
                len = start + 1;
                start = 0;
                loc = skpc(0xff, len, &ibp[0]);
                if (loc == 0) {
                        printf("cg = %d, ipref = %lld, fs = %s\n",
                                cg, (long long)ipref, fs->e2fs_fsmnt);
                        panic("ext2fs_nodealloccg: map corrupted");
                        /* NOTREACHED */
                }
        }
        i = start + len - loc;
        map = ibp[i] ^ 0xff;
        if (map == 0) {
                printf("fs = %s\n", fs->e2fs_fsmnt);
                panic("ext2fs_nodealloccg: block not in map");
        }
        ipref = i * NBBY + ffs(map) - 1;
gotit:
        setbit(ibp, ipref);
        fs->e2fs.e2fs_ficount--;
        fs->e2fs_gd[cg].ext2bgd_nifree--;
        fs->e2fs_fmod = 1;
        if ((mode & IFMT) == IFDIR) {
                fs->e2fs_gd[cg].ext2bgd_ndirs++;
        }
        bdwrite(bp);
        return (cg * fs->e2fs.e2fs_ipg + ipref +1);
}

/*
 * Free a block.
 *
 * The specified block is placed back in the
 * free map.
 */
void
ext2fs_blkfree(struct inode *ip, daddr_t bno)
{
        struct m_ext2fs *fs;
        char *bbp;
        struct buf *bp;
        int error, cg;

        fs = ip->i_e2fs;
        cg = dtog(fs, bno);
        if ((u_int)bno >= fs->e2fs.e2fs_bcount) {
                printf("bad block %lld, ino %llu\n", (long long)bno,
                    (unsigned long long)ip->i_number);
                ext2fs_fserr(fs, ip->i_uid, "bad block");
                return;
        }
        error = bread(ip->i_devvp,
                fsbtodb(fs, fs->e2fs_gd[cg].ext2bgd_b_bitmap),
                (int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
        if (error) {
                brelse(bp, 0);
                return;
        }
        bbp = (char *)bp->b_data;
        bno = dtogd(fs, bno);
        if (isclr(bbp, bno)) {
                printf("dev = 0x%llx, block = %lld, fs = %s\n",
                    (unsigned long long)ip->i_dev, (long long)bno,
                    fs->e2fs_fsmnt);
                panic("blkfree: freeing free block");
        }
        clrbit(bbp, bno);
        fs->e2fs.e2fs_fbcount++;
        fs->e2fs_gd[cg].ext2bgd_nbfree++;

        fs->e2fs_fmod = 1;
        bdwrite(bp);
}

/*
 * Free an inode.
 *
 * The specified inode is placed back in the free map.
 */
int
ext2fs_vfree(struct vnode *pvp, ino_t ino, int mode)
{
        struct m_ext2fs *fs;
        char *ibp;
        struct inode *pip;
        struct buf *bp;
        int error, cg;

        pip = VTOI(pvp);
        fs = pip->i_e2fs;
        if ((u_int)ino > fs->e2fs.e2fs_icount || (u_int)ino < EXT2_FIRSTINO)
                panic("ifree: range: dev = 0x%llx, ino = %llu, fs = %s",
                    (unsigned long long)pip->i_dev, (unsigned long long)ino,
                    fs->e2fs_fsmnt);
        cg = ino_to_cg(fs, ino);
        error = bread(pip->i_devvp,
                fsbtodb(fs, fs->e2fs_gd[cg].ext2bgd_i_bitmap),
                (int)fs->e2fs_bsize, NOCRED, B_MODIFY, &bp);
        if (error) {
                brelse(bp, 0);
                return (0);
        }
        ibp = (char *)bp->b_data;
        ino = (ino - 1) % fs->e2fs.e2fs_ipg;
        if (isclr(ibp, ino)) {
                printf("dev = 0x%llx, ino = %llu, fs = %s\n",
                    (unsigned long long)pip->i_dev,
                    (unsigned long long)ino, fs->e2fs_fsmnt);
                if (fs->e2fs_ronly == 0)
                        panic("ifree: freeing free inode");
        }
        clrbit(ibp, ino);
        fs->e2fs.e2fs_ficount++;
        fs->e2fs_gd[cg].ext2bgd_nifree++;
        if ((mode & IFMT) == IFDIR) {
                fs->e2fs_gd[cg].ext2bgd_ndirs--;
        }
        fs->e2fs_fmod = 1;
        bdwrite(bp);
        return (0);
}

/*
 * Find a block in the specified cylinder group.
 *
 * It is a panic if a request is made to find a block if none are
 * available.
 */

static daddr_t
ext2fs_mapsearch(struct m_ext2fs *fs, char *bbp, daddr_t bpref)
{
        int start, len, loc, i, map;

        /*
         * find the fragment by searching through the free block
         * map for an appropriate bit pattern
         */
        if (bpref)
                start = dtogd(fs, bpref) / NBBY;
        else
                start = 0;
        len = howmany(fs->e2fs.e2fs_fpg, NBBY) - start;
        loc = skpc(0xff, len, &bbp[start]);
        if (loc == 0) {
                len = start + 1;
                start = 0;
                loc = skpc(0xff, len, &bbp[start]);
                if (loc == 0) {
                        printf("start = %d, len = %d, fs = %s\n",
                                start, len, fs->e2fs_fsmnt);
                        panic("ext2fs_alloccg: map corrupted");
                        /* NOTREACHED */
                }
        }
        i = start + len - loc;
        map = bbp[i] ^ 0xff;
        if (map == 0) {
                printf("fs = %s\n", fs->e2fs_fsmnt);
                panic("ext2fs_mapsearch: block not in map");
        }
        return i * NBBY + ffs(map) - 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
ext2fs_fserr(struct m_ext2fs *fs, u_int uid, const char *cp)
{

        log(LOG_ERR, "uid %d on %s: %s\n", uid, fs->e2fs_fsmnt, cp);
}