sys/vfs/ufs/ffs_subr.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1989, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)ffs_subr.c  8.5 (Berkeley) 3/21/95
  34  * $FreeBSD: src/sys/ufs/ffs/ffs_subr.c,v 1.25 1999/12/29 04:55:04 peter Exp $
  35  * $DragonFly: src/sys/vfs/ufs/ffs_subr.c,v 1.13 2006/05/26 19:57:33 dillon Exp $
  36  */
  37
  38 #include <sys/param.h>
  39
  40 #ifndef _KERNEL
  41 #include "dinode.h"
  42 #include "fs.h"
  43 #else
  44 #include "opt_ddb.h"
  45
  46 #include <sys/systm.h>
  47 #include <sys/lock.h>
  48 #include <sys/vnode.h>
  49 #include <sys/buf.h>
  50 #include <sys/ucred.h>
  51 #include <sys/mount.h>
  52
  53 #include "quota.h"
  54 #include "inode.h"
  55 #include "fs.h"
  56 #include "ffs_extern.h"
  57
  58 /*
  59  * Return buffer with the contents of block "offset" from the beginning of
  60  * vnode "vp".  If "res" is non-zero, fill it in with a pointer to the
  61  * remaining space in the vnode.
  62  */
  63 int
  64 ffs_blkatoff(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp)
  65 {
  66         struct inode *ip;
  67         struct fs *fs;
  68         struct buf *bp;
  69         ufs_daddr_t lbn;
  70         int bsize, error;
  71
  72         ip = VTOI(vp);
  73         fs = ip->i_fs;
  74         lbn = lblkno(fs, uoffset);
  75         bsize = blksize(fs, ip, lbn);
  76
  77         *bpp = NULL;
  78         error = bread(vp, lblktodoff(fs, lbn), bsize, &bp);
  79         if (error) {
  80                 brelse(bp);
  81                 return (error);
  82         }
  83         if (res)
  84                 *res = (char *)bp->b_data + blkoff(fs, uoffset);
  85         *bpp = bp;
  86         return (0);
  87 }
  88
  89 /*
  90  * Return buffer with the contents of block "offset" from the beginning of
  91  * vnode "vp".  If "res" is non-zero, fill it in with a pointer to the
  92  * remaining space in the vnode.
  93  *
  94  * This version includes a read-ahead optimization.
  95  */
  96 int
  97 ffs_blkatoff_ra(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp,
  98                 int seqcount)
  99 {
 100         struct inode *ip;
 101         struct fs *fs;
 102         struct buf *bp;
 103         ufs_daddr_t lbn;
 104         ufs_daddr_t nextlbn;
 105         off_t base_loffset;
 106         off_t next_loffset;
 107         int bsize, error;
 108         int nextbsize;
 109
 110         ip = VTOI(vp);
 111         fs = ip->i_fs;
 112         lbn = lblkno(fs, uoffset);
 113         base_loffset = lblktodoff(fs, lbn);
 114         bsize = blksize(fs, ip, lbn);
 115
 116         nextlbn = lbn + 1;
 117         next_loffset = lblktodoff(fs, nextlbn);
 118
 119
 120         *bpp = NULL;
 121
 122         if (next_loffset >= ip->i_size) {
 123                 /*
 124                  * Do not do readahead if this is the last block
 125                  */
 126                 error = bread(vp, base_loffset, bsize, &bp);
 127         } else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
 128                 /*
 129                  * Try to cluster if we allowed to.
 130                  */
 131                 error = cluster_read(vp, (off_t)ip->i_size,
 132                                      base_loffset, bsize,
 133                                      MAXBSIZE, seqcount, &bp);
 134         } else if (seqcount > 1) {
 135                 /*
 136                  * Faked read ahead
 137                  */
 138                 nextbsize = blksize(fs, ip, nextlbn);
 139                 error = breadn(vp, base_loffset, bsize,
 140                                &next_loffset, &nextbsize, 1, &bp);
 141         } else {
 142                 /*
 143                  * Failing all of the above, just read what the
 144                  * user asked for. Interestingly, the same as
 145                  * the first option above.
 146                  */
 147                 error = bread(vp, base_loffset, bsize, &bp);
 148         }
 149         if (error) {
 150                 brelse(bp);
 151                 return (error);
 152         }
 153         if (res)
 154                 *res = (char *)bp->b_data + (int)(uoffset - base_loffset);
 155         *bpp = bp;
 156         return (0);
 157 }
 158
 159 #endif
 160
 161 /*
 162  * Update the frsum fields to reflect addition or deletion
 163  * of some frags.
 164  */
 165 void
 166 ffs_fragacct(struct fs *fs, int fragmap, int32_t fraglist[], int cnt)
 167 {
 168         int inblk;
 169         int field, subfield;
 170         int siz, pos;
 171
 172         /*
 173          * inblk represents a bitmap of fragment sizes which may be
 174          * contained in the data 'fragmap'.  e.g. if a fragment of size
 175          * 1 is available, bit 0 would be set.  inblk is shifted left
 176          * by one so we do not have to calculate (1 << (siz - 1)).
 177          *
 178          * fragment represents the data pattern we are trying to decipher,
 179          * we shift it left by one to align it with the 'around' and 'inside'
 180          * masks.
 181          *
 182          * around represents the bits around the subfield and is a mask.
 183          * inside represents what we must match within the mask, it is
 184          * basically the mask with the first and last bit set to 0, allowing
 185          * us to represent a whole fragment.
 186          *
 187          * When we find a match we bump our position by the size of the
 188          * matching fragment, then bump the position again:
 189          *
 190          * 010101010 fragmap (shifted left by 1)
 191          *       111 around mask
 192          *       010 inside mask
 193          *      111     (shifted by siz)
 194          *      010
 195          *     111      (shifted again)
 196          *     010
 197          */
 198         inblk = (int)(fragtbl[fs->fs_frag][fragmap]) << 1;
 199         fragmap <<= 1;
 200         for (siz = 1; siz < fs->fs_frag; siz++) {
 201                 if ((inblk & (1 << (siz + (fs->fs_frag % NBBY)))) == 0)
 202                         continue;
 203                 field = around[siz];
 204                 subfield = inside[siz];
 205                 for (pos = siz; pos <= fs->fs_frag; pos++) {
 206                         if ((fragmap & field) == subfield) {
 207                                 fraglist[siz] += cnt;
 208                                 pos += siz;
 209                                 field <<= siz;
 210                                 subfield <<= siz;
 211                         }
 212                         field <<= 1;
 213                         subfield <<= 1;
 214                 }
 215         }
 216 }
 217
 218 /*
 219  * block operations
 220  *
 221  * check if a block is available
 222  */
 223 int
 224 ffs_isblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
 225 {
 226         unsigned char mask;
 227
 228         switch ((int)fs->fs_frag) {
 229         case 8:
 230                 return (cp[h] == 0xff);
 231         case 4:
 232                 mask = 0x0f << ((h & 0x1) << 2);
 233                 return ((cp[h >> 1] & mask) == mask);
 234         case 2:
 235                 mask = 0x03 << ((h & 0x3) << 1);
 236                 return ((cp[h >> 2] & mask) == mask);
 237         case 1:
 238                 mask = 0x01 << (h & 0x7);
 239                 return ((cp[h >> 3] & mask) == mask);
 240         default:
 241                 panic("ffs_isblock");
 242         }
 243 }
 244
 245 /*
 246  * check if a block is free
 247  */
 248 int
 249 ffs_isfreeblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
 250 {
 251         switch ((int)fs->fs_frag) {
 252         case 8:
 253                 return (cp[h] == 0);
 254         case 4:
 255                 return ((cp[h >> 1] & (0x0f << ((h & 0x1) << 2))) == 0);
 256         case 2:
 257                 return ((cp[h >> 2] & (0x03 << ((h & 0x3) << 1))) == 0);
 258         case 1:
 259                 return ((cp[h >> 3] & (0x01 << (h & 0x7))) == 0);
 260         default:
 261                 panic("ffs_isfreeblock");
 262         }
 263 }
 264
 265 /*
 266  * take a block out of the map
 267  */
 268 void
 269 ffs_clrblock(struct fs *fs, u_char *cp, ufs_daddr_t h)
 270 {
 271         switch ((int)fs->fs_frag) {
 272         case 8:
 273                 cp[h] = 0;
 274                 return;
 275         case 4:
 276                 cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
 277                 return;
 278         case 2:
 279                 cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
 280                 return;
 281         case 1:
 282                 cp[h >> 3] &= ~(0x01 << (h & 0x7));
 283                 return;
 284         default:
 285                 panic("ffs_clrblock");
 286         }
 287 }
 288
 289 /*
 290  * put a block into the map
 291  */
 292 void
 293 ffs_setblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
 294 {
 295         switch ((int)fs->fs_frag) {
 296         case 8:
 297                 cp[h] = 0xff;
 298                 return;
 299         case 4:
 300                 cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
 301                 return;
 302         case 2:
 303                 cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
 304                 return;
 305         case 1:
 306                 cp[h >> 3] |= (0x01 << (h & 0x7));
 307                 return;
 308         default:
 309                 panic("ffs_setblock");
 310         }
 311 }