/*
   *  linux/fs/hpfs/alloc.c
   *
   *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 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;

  	u32 *bmp;

  	if (!(bmp = hpfs_map_bitmap(s, sec >> 14, &qbh, "chk"))) goto fail;

  	if ((cpu_to_le32(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;
  	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;
  	}

  	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;

  	u32 *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;

  	u32 *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;

  	u32 *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;

  		u32 *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;
  }