[funini.com] -> [kei@sodan] -> Kernel Reading

root/fs/hpfs/alloc.c

/* [<][>][^][v][top][bottom][index][help] */

DEFINITIONS

This source file includes following definitions.
  1. chk_if_allocated
  2. hpfs_chk_sectors
  3. alloc_in_bmp
  4. hpfs_alloc_sector
  5. alloc_in_dirband
  6. hpfs_alloc_if_possible_nolock
  7. hpfs_alloc_if_possible
  8. hpfs_free_sectors
  9. hpfs_check_free_dnodes
  10. hpfs_free_dnode
  11. hpfs_alloc_dnode
  12. hpfs_alloc_fnode
  13. hpfs_alloc_anode

/*
 *  linux/fs/hpfs/alloc.c
 *
 *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
 *
 *  HPFS bitmap operations
 */

#include "hpfs_fn.h"

static int hpfs_alloc_if_possible_nolock(struct super_block *s, secno sec);

/*
 * 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;
        unsigned *bmp;
        if (!(bmp = hpfs_map_bitmap(s, sec >> 14, &qbh, "chk"))) goto fail;
        if ((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 ((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;
        unsigned *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;
        }
        lock_super(s);
        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;
        }
        /*if (!tstbits(bmp, nr + n, n + forward)) {
                ret = bs + nr + n;
                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 (!bmp[i]) goto cont;
                if (n + forward >= 0x3f && bmp[i] != -1) goto cont;
                q = i<<5;
                if (i > 0) {
                        unsigned k = 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) || (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] &= ~(((1 << n) - 1) << (ret & 0x1f));
                hpfs_mark_4buffers_dirty(&qbh);
        }
        b:
        hpfs_brelse4(&qbh);
        uls:
        unlock_super(s);
        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, int lock)
{
        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;
        }
        if (lock) hpfs_lock_creation(s);
        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_nolock(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;
                        }
                }
        }
        if (lock) hpfs_unlock_creation(s);
        return sec;
}

static secno alloc_in_dirband(struct super_block *s, secno near, int lock)
{
        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;
        if (lock) hpfs_lock_creation(s);
        sec = alloc_in_bmp(s, (~0x3fff) | nr, 1, 0);
        if (lock) hpfs_unlock_creation(s);
        if (!sec) return 0;
        return ((sec & 0x3fff) << 2) + sbi->sb_dirband_start;
}

/* Alloc sector if it's free */

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

int hpfs_alloc_if_possible(struct super_block *s, secno sec)
{
        int r;
        hpfs_lock_creation(s);
        r = hpfs_alloc_if_possible_nolock(s, sec);
        hpfs_unlock_creation(s);
        return r;
}

/* Free sectors in bitmaps */

void hpfs_free_sectors(struct super_block *s, secno sec, unsigned n)
{
        struct quad_buffer_head qbh;
        unsigned *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;
        }
        lock_super(s);
        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"))) {
                unlock_super(s);
                return;
        }       
        new_tst:
        if ((bmp[(sec & 0x3fff) >> 5] >> (sec & 0x1f) & 1)) {
                hpfs_error(s, "sector %08x not allocated", sec);
                hpfs_brelse4(&qbh);
                unlock_super(s);
                return;
        }
        bmp[(sec & 0x3fff) >> 5] |= 1 << (sec & 0x1f);
        if (!--n) {
                hpfs_mark_4buffers_dirty(&qbh);
                hpfs_brelse4(&qbh);
                unlock_super(s);
                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;
        unsigned *bmp;
        struct quad_buffer_head qbh;
        if ((bmp = hpfs_map_dnode_bitmap(s, &qbh))) {
                for (j = 0; j < 512; j++) {
                        unsigned k;
                        if (!bmp[j]) continue;
                        for (k = 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++) {
                        unsigned k;
                        if (!bmp[j]) continue;
                        for (k = 0xf; k; k <<= 4)
                                if ((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;
                unsigned *bmp;
                unsigned ssec = (dno - hpfs_sb(s)->sb_dirband_start) / 4;
                lock_super(s);
                if (!(bmp = hpfs_map_dnode_bitmap(s, &qbh))) {
                        unlock_super(s);
                        return;
                }
                bmp[ssec >> 5] |= 1 << (ssec & 0x1f);
                hpfs_mark_4buffers_dirty(&qbh);
                hpfs_brelse4(&qbh);
                unlock_super(s);
        }
}

struct dnode *hpfs_alloc_dnode(struct super_block *s, secno near,
                         dnode_secno *dno, struct quad_buffer_head *qbh,
                         int lock)
{
        struct dnode *d;
        if (hpfs_count_one_bitmap(s, hpfs_sb(s)->sb_dmap) > FREE_DNODES_ADD) {
                if (!(*dno = alloc_in_dirband(s, near, lock)))
                        if (!(*dno = hpfs_alloc_sector(s, near, 4, 0, lock))) return NULL;
        } else {
                if (!(*dno = hpfs_alloc_sector(s, near, 4, 0, lock)))
                        if (!(*dno = alloc_in_dirband(s, near, lock))) return NULL;
        }
        if (!(d = hpfs_get_4sectors(s, *dno, qbh))) {
                hpfs_free_dnode(s, *dno);
                return NULL;
        }
        memset(d, 0, 2048);
        d->magic = DNODE_MAGIC;
        d->first_free = 52;
        d->dirent[0] = 32;
        d->dirent[2] = 8;
        d->dirent[30] = 1;
        d->dirent[31] = 255;
        d->self = *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, 1))) return NULL;
        if (!(f = hpfs_get_sector(s, *fno, bh))) {
                hpfs_free_sectors(s, *fno, 1);
                return NULL;
        }       
        memset(f, 0, 512);
        f->magic = FNODE_MAGIC;
        f->ea_offs = 0xc4;
        f->btree.n_free_nodes = 8;
        f->btree.first_free = 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, 1))) return NULL;
        if (!(a = hpfs_get_sector(s, *ano, bh))) {
                hpfs_free_sectors(s, *ano, 1);
                return NULL;
        }
        memset(a, 0, 512);
        a->magic = ANODE_MAGIC;
        a->self = *ano;
        a->btree.n_free_nodes = 40;
        a->btree.n_used_nodes = 0;
        a->btree.first_free = 8;
        return a;
}

/* [<][>][^][v][top][bottom][index][help] */

[funini.com] -> [kei@sodan] -> Kernel Reading