alloc.c

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/*
 *  linux/fs/hpfs/alloc.c
 *
 *  Mikulas Patocka ([email protected]), 1998-1999
 *
 *  HPFS bitmap operations
 */

#include "hpfs_fn.h"

/*
 * Check if a sector is allocated in bitmap
 * This is really slow. Turned on only if chk==2
 */

static int chk_if_allocated(struct super_block *s, secno sec, char *msg)
{
    struct quad_buffer_head qbh;
    __le32 *bmp;
    if (!(bmp = hpfs_map_bitmap(s, sec >> 14, &qbh, "chk"))) goto fail;
    if ((le32_to_cpu(bmp[(sec & 0x3fff) >> 5]) >> (sec & 0x1f)) & 1) {
        hpfs_error(s, "sector '%s' - %08x not allocated in bitmap", msg, sec);
        goto fail1;
    }
    hpfs_brelse4(&qbh);
    if (sec >= hpfs_sb(s)->sb_dirband_start && sec < hpfs_sb(s)->sb_dirband_start + hpfs_sb(s)->sb_dirband_size) {
        unsigned ssec = (sec - hpfs_sb(s)->sb_dirband_start) / 4;
        if (!(bmp = hpfs_map_dnode_bitmap(s, &qbh))) goto fail;
        if ((le32_to_cpu(bmp[ssec >> 5]) >> (ssec & 0x1f)) & 1) {
            hpfs_error(s, "sector '%s' - %08x not allocated in directory bitmap", msg, sec);
            goto fail1;
        }
        hpfs_brelse4(&qbh);
    }
    return 0;
    fail1:
    hpfs_brelse4(&qbh);
    fail:
    return 1;
}

/*
 * Check if sector(s) have proper number and additionally check if they're
 * allocated in bitmap.
 */
    
int hpfs_chk_sectors(struct super_block *s, secno start, int len, char *msg)
{
    if (start + len < start || start < 0x12 ||
        start + len > hpfs_sb(s)->sb_fs_size) {
            hpfs_error(s, "sector(s) '%s' badly placed at %08x", msg, start);
        return 1;
    }
    if (hpfs_sb(s)->sb_chk>=2) {
        int i;
        for (i = 0; i < len; i++)
            if (chk_if_allocated(s, start + i, msg)) return 1;
    }
    return 0;
}

static secno alloc_in_bmp(struct super_block *s, secno near, unsigned n, unsigned forward)
{
    struct quad_buffer_head qbh;
    __le32 *bmp;
    unsigned bs = near & ~0x3fff;
    unsigned nr = (near & 0x3fff) & ~(n - 1);
    /*unsigned mnr;*/
    unsigned i, q;
    int a, b;
    secno ret = 0;
    if (n != 1 && n != 4) {
        hpfs_error(s, "Bad allocation size: %d", n);
        return 0;
    }
    if (bs != ~0x3fff) {
        if (!(bmp = hpfs_map_bitmap(s, near >> 14, &qbh, "aib"))) goto uls;
    } else {
        if (!(bmp = hpfs_map_dnode_bitmap(s, &qbh))) goto uls;
    }
    if (!tstbits(bmp, nr, n + forward)) {
        ret = bs + nr;
        goto rt;
    }
    q = nr + n; b = 0;
    while ((a = tstbits(bmp, q, n + forward)) != 0) {
        q += a;
        if (n != 1) q = ((q-1)&~(n-1))+n;
        if (!b) {
            if (q>>5 != nr>>5) {
                b = 1;
                q = nr & 0x1f;
            }
        } else if (q > nr) break;
    }
    if (!a) {
        ret = bs + q;
        goto rt;
    }
    nr >>= 5;
    /*for (i = nr + 1; i != nr; i++, i &= 0x1ff) */
    i = nr;
    do {
        if (!le32_to_cpu(bmp[i])) goto cont;
        if (n + forward >= 0x3f && le32_to_cpu(bmp[i]) != 0xffffffff) goto cont;
        q = i<<5;
        if (i > 0) {
            unsigned k = le32_to_cpu(bmp[i-1]);
            while (k & 0x80000000) {
                q--; k <<= 1;
            }
        }
        if (n != 1) q = ((q-1)&~(n-1))+n;
        while ((a = tstbits(bmp, q, n + forward)) != 0) {
            q += a;
            if (n != 1) q = ((q-1)&~(n-1))+n;
            if (q>>5 > i) break;
        }
        if (!a) {
            ret = bs + q;
            goto rt;
        }
        cont:
        i++, i &= 0x1ff;
    } while (i != nr);
    rt:
    if (ret) {
        if (hpfs_sb(s)->sb_chk && ((ret >> 14) != (bs >> 14) || (le32_to_cpu(bmp[(ret & 0x3fff) >> 5]) | ~(((1 << n) - 1) << (ret & 0x1f))) != 0xffffffff)) {
            hpfs_error(s, "Allocation doesn't work! Wanted %d, allocated at %08x", n, ret);
            ret = 0;
            goto b;
        }
        bmp[(ret & 0x3fff) >> 5] &= cpu_to_le32(~(((1 << n) - 1) << (ret & 0x1f)));
        hpfs_mark_4buffers_dirty(&qbh);
    }
    b:
    hpfs_brelse4(&qbh);
    uls:
    return ret;
}

/*
 * Allocation strategy: 1) search place near the sector specified
 *          2) search bitmap where free sectors last found
 *          3) search all bitmaps
 *          4) search all bitmaps ignoring number of pre-allocated
 *              sectors
 */

secno hpfs_alloc_sector(struct super_block *s, secno near, unsigned n, int forward)
{
    secno sec;
    int i;
    unsigned n_bmps;
    struct hpfs_sb_info *sbi = hpfs_sb(s);
    int f_p = 0;
    int near_bmp;
    if (forward < 0) {
        forward = -forward;
        f_p = 1;
    }
    n_bmps = (sbi->sb_fs_size + 0x4000 - 1) >> 14;
    if (near && near < sbi->sb_fs_size) {
        if ((sec = alloc_in_bmp(s, near, n, f_p ? forward : forward/4))) goto ret;
        near_bmp = near >> 14;
    } else near_bmp = n_bmps / 2;
    /*
    if (b != -1) {
        if ((sec = alloc_in_bmp(s, b<<14, n, f_p ? forward : forward/2))) {
            b &= 0x0fffffff;
            goto ret;
        }
        if (b > 0x10000000) if ((sec = alloc_in_bmp(s, (b&0xfffffff)<<14, n, f_p ? forward : 0))) goto ret;
    */
    if (!f_p) if (forward > sbi->sb_max_fwd_alloc) forward = sbi->sb_max_fwd_alloc;
    less_fwd:
    for (i = 0; i < n_bmps; i++) {
        if (near_bmp+i < n_bmps && ((sec = alloc_in_bmp(s, (near_bmp+i) << 14, n, forward)))) {
            sbi->sb_c_bitmap = near_bmp+i;
            goto ret;
        }   
        if (!forward) {
            if (near_bmp-i-1 >= 0 && ((sec = alloc_in_bmp(s, (near_bmp-i-1) << 14, n, forward)))) {
                sbi->sb_c_bitmap = near_bmp-i-1;
                goto ret;
            }
        } else {
            if (near_bmp+i >= n_bmps && ((sec = alloc_in_bmp(s, (near_bmp+i-n_bmps) << 14, n, forward)))) {
                sbi->sb_c_bitmap = near_bmp+i-n_bmps;
                goto ret;
            }
        }
        if (i == 1 && sbi->sb_c_bitmap != -1 && ((sec = alloc_in_bmp(s, (sbi->sb_c_bitmap) << 14, n, forward)))) {
            goto ret;
        }
    }
    if (!f_p) {
        if (forward) {
            sbi->sb_max_fwd_alloc = forward * 3 / 4;
            forward /= 2;
            goto less_fwd;
        }
    }
    sec = 0;
    ret:
    if (sec && f_p) {
        for (i = 0; i < forward; i++) {
            if (!hpfs_alloc_if_possible(s, sec + i + 1)) {
                hpfs_error(s, "Prealloc doesn't work! Wanted %d, allocated at %08x, can't allocate %d", forward, sec, i);
                sec = 0;
                break;
            }
        }
    }
    return sec;
}

static secno alloc_in_dirband(struct super_block *s, secno near)
{
    unsigned nr = near;
    secno sec;
    struct hpfs_sb_info *sbi = hpfs_sb(s);
    if (nr < sbi->sb_dirband_start)
        nr = sbi->sb_dirband_start;
    if (nr >= sbi->sb_dirband_start + sbi->sb_dirband_size)
        nr = sbi->sb_dirband_start + sbi->sb_dirband_size - 4;
    nr -= sbi->sb_dirband_start;
    nr >>= 2;
    sec = alloc_in_bmp(s, (~0x3fff) | nr, 1, 0);
    if (!sec) return 0;
    return ((sec & 0x3fff) << 2) + sbi->sb_dirband_start;
}

/* Alloc sector if it's free */

int hpfs_alloc_if_possible(struct super_block *s, secno sec)
{
    struct quad_buffer_head qbh;
    __le32 *bmp;
    if (!(bmp = hpfs_map_bitmap(s, sec >> 14, &qbh, "aip"))) goto end;
    if (le32_to_cpu(bmp[(sec & 0x3fff) >> 5]) & (1 << (sec & 0x1f))) {
        bmp[(sec & 0x3fff) >> 5] &= cpu_to_le32(~(1 << (sec & 0x1f)));
        hpfs_mark_4buffers_dirty(&qbh);
        hpfs_brelse4(&qbh);
        return 1;
    }
    hpfs_brelse4(&qbh);
    end:
    return 0;
}

/* Free sectors in bitmaps */

void hpfs_free_sectors(struct super_block *s, secno sec, unsigned n)
{
    struct quad_buffer_head qbh;
    __le32 *bmp;
    struct hpfs_sb_info *sbi = hpfs_sb(s);
    /*printk("2 - ");*/
    if (!n) return;
    if (sec < 0x12) {
        hpfs_error(s, "Trying to free reserved sector %08x", sec);
        return;
    }
    sbi->sb_max_fwd_alloc += n > 0xffff ? 0xffff : n;
    if (sbi->sb_max_fwd_alloc > 0xffffff) sbi->sb_max_fwd_alloc = 0xffffff;
    new_map:
    if (!(bmp = hpfs_map_bitmap(s, sec >> 14, &qbh, "free"))) {
        return;
    }   
    new_tst:
    if ((le32_to_cpu(bmp[(sec & 0x3fff) >> 5]) >> (sec & 0x1f) & 1)) {
        hpfs_error(s, "sector %08x not allocated", sec);
        hpfs_brelse4(&qbh);
        return;
    }
    bmp[(sec & 0x3fff) >> 5] |= cpu_to_le32(1 << (sec & 0x1f));
    if (!--n) {
        hpfs_mark_4buffers_dirty(&qbh);
        hpfs_brelse4(&qbh);
        return;
    }   
    if (!(++sec & 0x3fff)) {
        hpfs_mark_4buffers_dirty(&qbh);
        hpfs_brelse4(&qbh);
        goto new_map;
    }
    goto new_tst;
}

/*
 * Check if there are at least n free dnodes on the filesystem.
 * Called before adding to dnode. If we run out of space while
 * splitting dnodes, it would corrupt dnode tree.
 */

int hpfs_check_free_dnodes(struct super_block *s, int n)
{
    int n_bmps = (hpfs_sb(s)->sb_fs_size + 0x4000 - 1) >> 14;
    int b = hpfs_sb(s)->sb_c_bitmap & 0x0fffffff;
    int i, j;
    __le32 *bmp;
    struct quad_buffer_head qbh;
    if ((bmp = hpfs_map_dnode_bitmap(s, &qbh))) {
        for (j = 0; j < 512; j++) {
            unsigned k;
            if (!le32_to_cpu(bmp[j])) continue;
            for (k = le32_to_cpu(bmp[j]); k; k >>= 1) if (k & 1) if (!--n) {
                hpfs_brelse4(&qbh);
                return 0;
            }
        }
    }
    hpfs_brelse4(&qbh);
    i = 0;
    if (hpfs_sb(s)->sb_c_bitmap != -1) {
        bmp = hpfs_map_bitmap(s, b, &qbh, "chkdn1");
        goto chk_bmp;
    }
    chk_next:
    if (i == b) i++;
    if (i >= n_bmps) return 1;
    bmp = hpfs_map_bitmap(s, i, &qbh, "chkdn2");
    chk_bmp:
    if (bmp) {
        for (j = 0; j < 512; j++) {
            u32 k;
            if (!le32_to_cpu(bmp[j])) continue;
            for (k = 0xf; k; k <<= 4)
                if ((le32_to_cpu(bmp[j]) & k) == k) {
                    if (!--n) {
                        hpfs_brelse4(&qbh);
                        return 0;
                    }
                }
        }
        hpfs_brelse4(&qbh);
    }
    i++;
    goto chk_next;
}

void hpfs_free_dnode(struct super_block *s, dnode_secno dno)
{
    if (hpfs_sb(s)->sb_chk) if (dno & 3) {
        hpfs_error(s, "hpfs_free_dnode: dnode %08x not aligned", dno);
        return;
    }
    if (dno < hpfs_sb(s)->sb_dirband_start ||
        dno >= hpfs_sb(s)->sb_dirband_start + hpfs_sb(s)->sb_dirband_size) {
        hpfs_free_sectors(s, dno, 4);
    } else {
        struct quad_buffer_head qbh;
        __le32 *bmp;
        unsigned ssec = (dno - hpfs_sb(s)->sb_dirband_start) / 4;
        if (!(bmp = hpfs_map_dnode_bitmap(s, &qbh))) {
            return;
        }
        bmp[ssec >> 5] |= cpu_to_le32(1 << (ssec & 0x1f));
        hpfs_mark_4buffers_dirty(&qbh);
        hpfs_brelse4(&qbh);
    }
}

struct dnode *hpfs_alloc_dnode(struct super_block *s, secno near,
             dnode_secno *dno, struct quad_buffer_head *qbh)
{
    struct dnode *d;
    if (hpfs_count_one_bitmap(s, hpfs_sb(s)->sb_dmap) > FREE_DNODES_ADD) {
        if (!(*dno = alloc_in_dirband(s, near)))
            if (!(*dno = hpfs_alloc_sector(s, near, 4, 0))) return NULL;
    } else {
        if (!(*dno = hpfs_alloc_sector(s, near, 4, 0)))
            if (!(*dno = alloc_in_dirband(s, near))) return NULL;
    }
    if (!(d = hpfs_get_4sectors(s, *dno, qbh))) {
        hpfs_free_dnode(s, *dno);
        return NULL;
    }
    memset(d, 0, 2048);
    d->magic = cpu_to_le32(DNODE_MAGIC);
    d->first_free = cpu_to_le32(52);
    d->dirent[0] = 32;
    d->dirent[2] = 8;
    d->dirent[30] = 1;
    d->dirent[31] = 255;
    d->self = cpu_to_le32(*dno);
    return d;
}

struct fnode *hpfs_alloc_fnode(struct super_block *s, secno near, fnode_secno *fno,
              struct buffer_head **bh)
{
    struct fnode *f;
    if (!(*fno = hpfs_alloc_sector(s, near, 1, FNODE_ALLOC_FWD))) return NULL;
    if (!(f = hpfs_get_sector(s, *fno, bh))) {
        hpfs_free_sectors(s, *fno, 1);
        return NULL;
    }   
    memset(f, 0, 512);
    f->magic = cpu_to_le32(FNODE_MAGIC);
    f->ea_offs = cpu_to_le16(0xc4);
    f->btree.n_free_nodes = 8;
    f->btree.first_free = cpu_to_le16(8);
    return f;
}

struct anode *hpfs_alloc_anode(struct super_block *s, secno near, anode_secno *ano,
              struct buffer_head **bh)
{
    struct anode *a;
    if (!(*ano = hpfs_alloc_sector(s, near, 1, ANODE_ALLOC_FWD))) return NULL;
    if (!(a = hpfs_get_sector(s, *ano, bh))) {
        hpfs_free_sectors(s, *ano, 1);
        return NULL;
    }
    memset(a, 0, 512);
    a->magic = cpu_to_le32(ANODE_MAGIC);
    a->self = cpu_to_le32(*ano);
    a->btree.n_free_nodes = 40;
    a->btree.n_used_nodes = 0;
    a->btree.first_free = cpu_to_le16(8);
    return a;
}