The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/fs/ext2fs/ext2_alloc.c

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    1 /*-
    2  *  modified for Lites 1.1
    3  *
    4  *  Aug 1995, Godmar Back (gback@cs.utah.edu)
    5  *  University of Utah, Department of Computer Science
    6  */
    7 /*-
    8  * Copyright (c) 1982, 1986, 1989, 1993
    9  *      The Regents of the University of California.  All rights reserved.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 4. Neither the name of the University nor the names of its contributors
   20  *    may be used to endorse or promote products derived from this software
   21  *    without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  *
   35  *      @(#)ffs_alloc.c 8.8 (Berkeley) 2/21/94
   36  * $FreeBSD: releng/9.0/sys/fs/ext2fs/ext2_alloc.c 221126 2011-04-27 18:15:34Z jhb $
   37  */
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/conf.h>
   42 #include <sys/vnode.h>
   43 #include <sys/stat.h>
   44 #include <sys/mount.h>
   45 #include <sys/syslog.h>
   46 #include <sys/buf.h>
   47 
   48 #include <fs/ext2fs/inode.h>
   49 #include <fs/ext2fs/ext2_mount.h>
   50 #include <fs/ext2fs/ext2fs.h>
   51 #include <fs/ext2fs/fs.h>
   52 #include <fs/ext2fs/ext2_extern.h>
   53 
   54 static daddr_t  ext2_alloccg(struct inode *, int, daddr_t, int);
   55 static u_long   ext2_dirpref(struct inode *);
   56 static void     ext2_fserr(struct m_ext2fs *, uid_t, char *);
   57 static u_long   ext2_hashalloc(struct inode *, int, long, int,
   58                                 daddr_t (*)(struct inode *, int, daddr_t, 
   59                                                 int));
   60 static daddr_t  ext2_nodealloccg(struct inode *, int, daddr_t, int);
   61 static daddr_t  ext2_mapsearch(struct m_ext2fs *, char *, daddr_t);
   62 #ifdef FANCY_REALLOC
   63 static int      ext2_reallocblks(struct vop_reallocblks_args *);
   64 #endif
   65 
   66 /*
   67  * Allocate a block in the file system.
   68  *
   69  * A preference may be optionally specified. If a preference is given
   70  * the following hierarchy is used to allocate a block:
   71  *   1) allocate the requested block.
   72  *   2) allocate a rotationally optimal block in the same cylinder.
   73  *   3) allocate a block in the same cylinder group.
   74  *   4) quadradically rehash into other cylinder groups, until an
   75  *        available block is located.
   76  * If no block preference is given the following hierarchy is used
   77  * to allocate a block:
   78  *   1) allocate a block in the cylinder group that contains the
   79  *        inode for the file.
   80  *   2) quadradically rehash into other cylinder groups, until an
   81  *        available block is located.
   82  */
   83 int
   84 ext2_alloc(ip, lbn, bpref, size, cred, bnp)
   85         struct inode *ip;
   86         int32_t lbn, bpref;
   87         int size;
   88         struct ucred *cred;
   89         int32_t *bnp;
   90 {
   91         struct m_ext2fs *fs;
   92         struct ext2mount *ump;
   93         int32_t bno;
   94         int cg; 
   95         *bnp = 0;
   96         fs = ip->i_e2fs;
   97         ump = ip->i_ump;
   98         mtx_assert(EXT2_MTX(ump), MA_OWNED);
   99 #ifdef DIAGNOSTIC
  100         if ((u_int)size > fs->e2fs_bsize || blkoff(fs, size) != 0) {
  101                 vn_printf(ip->i_devvp, "bsize = %lu, size = %d, fs = %s\n",
  102                     (long unsigned int)fs->e2fs_bsize, size, fs->e2fs_fsmnt);
  103                 panic("ext2_alloc: bad size");
  104         }
  105         if (cred == NOCRED)
  106                 panic("ext2_alloc: missing credential");
  107 #endif /* DIAGNOSTIC */
  108         if (size == fs->e2fs_bsize && fs->e2fs->e2fs_fbcount == 0)
  109                 goto nospace;
  110         if (cred->cr_uid != 0 && 
  111                 fs->e2fs->e2fs_fbcount < fs->e2fs->e2fs_rbcount)
  112                 goto nospace;
  113         if (bpref >= fs->e2fs->e2fs_bcount)
  114                 bpref = 0;
  115         if (bpref == 0)
  116                 cg = ino_to_cg(fs, ip->i_number);
  117         else
  118                 cg = dtog(fs, bpref);
  119         bno = (daddr_t)ext2_hashalloc(ip, cg, bpref, fs->e2fs_bsize,
  120                                                  ext2_alloccg);
  121         if (bno > 0) {
  122                 /* set next_alloc fields as done in block_getblk */
  123                 ip->i_next_alloc_block = lbn;
  124                 ip->i_next_alloc_goal = bno;
  125 
  126                 ip->i_blocks += btodb(fs->e2fs_bsize);
  127                 ip->i_flag |= IN_CHANGE | IN_UPDATE;
  128                 *bnp = bno;
  129                 return (0);
  130         }
  131 nospace:
  132         EXT2_UNLOCK(ump);
  133         ext2_fserr(fs, cred->cr_uid, "file system full");
  134         uprintf("\n%s: write failed, file system is full\n", fs->e2fs_fsmnt);
  135         return (ENOSPC);
  136 }
  137 
  138 /*
  139  * Reallocate a sequence of blocks into a contiguous sequence of blocks.
  140  *
  141  * The vnode and an array of buffer pointers for a range of sequential
  142  * logical blocks to be made contiguous is given. The allocator attempts
  143  * to find a range of sequential blocks starting as close as possible to
  144  * an fs_rotdelay offset from the end of the allocation for the logical
  145  * block immediately preceding the current range. If successful, the
  146  * physical block numbers in the buffer pointers and in the inode are
  147  * changed to reflect the new allocation. If unsuccessful, the allocation
  148  * is left unchanged. The success in doing the reallocation is returned.
  149  * Note that the error return is not reflected back to the user. Rather
  150  * the previous block allocation will be used.
  151  */
  152 
  153 #ifdef FANCY_REALLOC
  154 SYSCTL_NODE(_vfs, OID_AUTO, ext2fs, CTLFLAG_RW, 0, "EXT2FS filesystem");
  155 
  156 static int doasyncfree = 1;
  157 SYSCTL_INT(_vfs_ext2fs, OID_AUTO, doasyncfree, CTLFLAG_RW, &doasyncfree, 0,
  158     "Use asychronous writes to update block pointers when freeing blocks");
  159 
  160 static int doreallocblks = 1;
  161 SYSCTL_INT(_vfs_ext2fs, OID_AUTO, doreallocblks, CTLFLAG_RW, &doreallocblks, 0, "");
  162 #endif
  163 
  164 int
  165 ext2_reallocblks(ap)
  166         struct vop_reallocblks_args /* {
  167                 struct vnode *a_vp;
  168                 struct cluster_save *a_buflist;
  169         } */ *ap;
  170 {
  171 #ifndef FANCY_REALLOC
  172 /* printf("ext2_reallocblks not implemented\n"); */
  173 return ENOSPC;
  174 #else
  175 
  176         struct m_ext2fs *fs;
  177         struct inode *ip;
  178         struct vnode *vp;
  179         struct buf *sbp, *ebp;
  180         int32_t *bap, *sbap, *ebap = 0;
  181         struct ext2mount *ump;
  182         struct cluster_save *buflist;
  183         struct indir start_ap[NIADDR + 1], end_ap[NIADDR + 1], *idp;
  184         int32_t start_lbn, end_lbn, soff, newblk, blkno;
  185         int i, len, start_lvl, end_lvl, pref, ssize;
  186 
  187         vp = ap->a_vp;
  188         ip = VTOI(vp);
  189         fs = ip->i_e2fs;
  190         ump = ip->i_ump;
  191 #ifdef UNKLAR
  192         if (fs->fs_contigsumsize <= 0)
  193                 return (ENOSPC);
  194 #endif
  195         buflist = ap->a_buflist;
  196         len = buflist->bs_nchildren;
  197         start_lbn = buflist->bs_children[0]->b_lblkno;
  198         end_lbn = start_lbn + len - 1;
  199 #ifdef DIAGNOSTIC
  200         for (i = 1; i < len; i++)
  201                 if (buflist->bs_children[i]->b_lblkno != start_lbn + i)
  202                         panic("ext2_reallocblks: non-cluster");
  203 #endif
  204         /*
  205          * If the latest allocation is in a new cylinder group, assume that
  206          * the filesystem has decided to move and do not force it back to
  207          * the previous cylinder group.
  208          */
  209         if (dtog(fs, dbtofsb(fs, buflist->bs_children[0]->b_blkno)) !=
  210             dtog(fs, dbtofsb(fs, buflist->bs_children[len - 1]->b_blkno)))
  211                 return (ENOSPC);
  212         if (ext2_getlbns(vp, start_lbn, start_ap, &start_lvl) ||
  213             ext2_getlbns(vp, end_lbn, end_ap, &end_lvl))
  214                 return (ENOSPC);
  215         /*
  216          * Get the starting offset and block map for the first block.
  217          */
  218         if (start_lvl == 0) {
  219                 sbap = &ip->i_db[0];
  220                 soff = start_lbn;
  221         } else {
  222                 idp = &start_ap[start_lvl - 1];
  223                 if (bread(vp, idp->in_lbn, (int)fs->e2fs_bsize, NOCRED, &sbp)) {
  224                         brelse(sbp);
  225                         return (ENOSPC);
  226                 }
  227                 sbap = (int32_t *)sbp->b_data;
  228                 soff = idp->in_off;
  229         }
  230         /*
  231          * Find the preferred location for the cluster.
  232          */
  233         EXT2_LOCK(ump);
  234         pref = ext2_blkpref(ip, start_lbn, soff, sbap, 0);
  235         /*
  236          * If the block range spans two block maps, get the second map.
  237          */
  238         if (end_lvl == 0 || (idp = &end_ap[end_lvl - 1])->in_off + 1 >= len) {
  239                 ssize = len;
  240         } else {
  241 #ifdef DIAGNOSTIC
  242                 if (start_ap[start_lvl-1].in_lbn == idp->in_lbn)
  243                         panic("ext2_reallocblk: start == end");
  244 #endif
  245                 ssize = len - (idp->in_off + 1);
  246                 if (bread(vp, idp->in_lbn, (int)fs->e2fs_bsize, NOCRED, &ebp)){
  247                         EXT2_UNLOCK(ump);       
  248                         goto fail;
  249                 }
  250                 ebap = (int32_t *)ebp->b_data;
  251         }
  252         /*
  253          * Search the block map looking for an allocation of the desired size.
  254          */
  255         if ((newblk = (int32_t)ext2_hashalloc(ip, dtog(fs, pref), pref,
  256             len, ext2_clusteralloc)) == 0){
  257                 EXT2_UNLOCK(ump);
  258                 goto fail;
  259         }       
  260         /*
  261          * We have found a new contiguous block.
  262          *
  263          * First we have to replace the old block pointers with the new
  264          * block pointers in the inode and indirect blocks associated
  265          * with the file.
  266          */
  267         blkno = newblk;
  268         for (bap = &sbap[soff], i = 0; i < len; i++, blkno += fs->e2fs_fpb) {
  269                 if (i == ssize)
  270                         bap = ebap;
  271                         soff = -i;
  272 #ifdef DIAGNOSTIC
  273                 if (buflist->bs_children[i]->b_blkno != fsbtodb(fs, *bap))
  274                         panic("ext2_reallocblks: alloc mismatch");
  275 #endif
  276                 *bap++ = blkno;
  277         }
  278         /*
  279          * Next we must write out the modified inode and indirect blocks.
  280          * For strict correctness, the writes should be synchronous since
  281          * the old block values may have been written to disk. In practise
  282          * they are almost never written, but if we are concerned about 
  283          * strict correctness, the `doasyncfree' flag should be set to zero.
  284          *
  285          * The test on `doasyncfree' should be changed to test a flag
  286          * that shows whether the associated buffers and inodes have
  287          * been written. The flag should be set when the cluster is
  288          * started and cleared whenever the buffer or inode is flushed.
  289          * We can then check below to see if it is set, and do the
  290          * synchronous write only when it has been cleared.
  291          */
  292         if (sbap != &ip->i_db[0]) {
  293                 if (doasyncfree)
  294                         bdwrite(sbp);
  295                 else
  296                         bwrite(sbp);
  297         } else {
  298                 ip->i_flag |= IN_CHANGE | IN_UPDATE;
  299                 if (!doasyncfree)
  300                         ext2_update(vp, 1);
  301         }
  302         if (ssize < len) {
  303                 if (doasyncfree)
  304                         bdwrite(ebp);
  305                 else
  306                         bwrite(ebp);
  307         }
  308         /*
  309          * Last, free the old blocks and assign the new blocks to the buffers.
  310          */
  311         for (blkno = newblk, i = 0; i < len; i++, blkno += fs->e2fs_fpb) {
  312                 ext2_blkfree(ip, dbtofsb(fs, buflist->bs_children[i]->b_blkno),
  313                     fs->e2fs_bsize);
  314                 buflist->bs_children[i]->b_blkno = fsbtodb(fs, blkno);
  315         }
  316         return (0);
  317 
  318 fail:
  319         if (ssize < len)
  320                 brelse(ebp);
  321         if (sbap != &ip->i_db[0])
  322                 brelse(sbp);
  323         return (ENOSPC);
  324 
  325 #endif /* FANCY_REALLOC */
  326 }
  327 
  328 /*
  329  * Allocate an inode in the file system.
  330  * 
  331  */
  332 int
  333 ext2_valloc(pvp, mode, cred, vpp)
  334         struct vnode *pvp;
  335         int mode;
  336         struct ucred *cred;
  337         struct vnode **vpp;
  338 {
  339         struct inode *pip;
  340         struct m_ext2fs *fs;
  341         struct inode *ip;
  342         struct ext2mount *ump;
  343         ino_t ino, ipref;
  344         int i, error, cg;
  345         
  346         *vpp = NULL;
  347         pip = VTOI(pvp);
  348         fs = pip->i_e2fs;
  349         ump = pip->i_ump;
  350 
  351         EXT2_LOCK(ump);
  352         if (fs->e2fs->e2fs_ficount == 0)
  353                 goto noinodes;
  354         /*
  355          * If it is a directory then obtain a cylinder group based on
  356          * ext2_dirpref else obtain it using ino_to_cg. The preferred inode is
  357          * always the next inode.
  358          */
  359         if((mode & IFMT) == IFDIR) {
  360                 cg = ext2_dirpref(pip);
  361                 if (fs->e2fs_contigdirs[cg] < 255)
  362                         fs->e2fs_contigdirs[cg]++;
  363         } else {
  364                 cg = ino_to_cg(fs, pip->i_number);
  365                 if (fs->e2fs_contigdirs[cg] > 0)
  366                         fs->e2fs_contigdirs[cg]--;
  367         }
  368         ipref = cg * fs->e2fs->e2fs_ipg + 1;
  369         ino = (ino_t)ext2_hashalloc(pip, cg, (long)ipref, mode, ext2_nodealloccg);
  370 
  371         if (ino == 0) 
  372                 goto noinodes;
  373         error = VFS_VGET(pvp->v_mount, ino, LK_EXCLUSIVE, vpp);
  374         if (error) {
  375                 ext2_vfree(pvp, ino, mode);
  376                 return (error);
  377         }
  378         ip = VTOI(*vpp);
  379 
  380         /* 
  381           the question is whether using VGET was such good idea at all -
  382           Linux doesn't read the old inode in when it's allocating a
  383           new one. I will set at least i_size & i_blocks the zero. 
  384         */ 
  385         ip->i_mode = 0;
  386         ip->i_size = 0;
  387         ip->i_blocks = 0;
  388         ip->i_flags = 0;
  389         /* now we want to make sure that the block pointers are zeroed out */
  390         for (i = 0; i < NDADDR; i++)
  391                 ip->i_db[i] = 0;
  392         for (i = 0; i < NIADDR; i++)
  393                 ip->i_ib[i] = 0;
  394 
  395         /*
  396          * Set up a new generation number for this inode.
  397          * XXX check if this makes sense in ext2
  398          */
  399         if (ip->i_gen == 0 || ++ip->i_gen == 0)
  400                 ip->i_gen = random() / 2 + 1;
  401 /*
  402 printf("ext2_valloc: allocated inode %d\n", ino);
  403 */
  404         return (0);
  405 noinodes:
  406         EXT2_UNLOCK(ump);
  407         ext2_fserr(fs, cred->cr_uid, "out of inodes");
  408         uprintf("\n%s: create/symlink failed, no inodes free\n", fs->e2fs_fsmnt);
  409         return (ENOSPC);
  410 }
  411 
  412 /*
  413  * Find a cylinder to place a directory.
  414  *
  415  * The policy implemented by this algorithm is to allocate a
  416  * directory inode in the same cylinder group as its parent
  417  * directory, but also to reserve space for its files inodes
  418  * and data. Restrict the number of directories which may be
  419  * allocated one after another in the same cylinder group
  420  * without intervening allocation of files.
  421  *
  422  * If we allocate a first level directory then force allocation
  423  * in another cylinder group.
  424  *
  425  */
  426 static u_long
  427 ext2_dirpref(struct inode *pip)
  428 {
  429         struct m_ext2fs *fs;
  430         int cg, prefcg, dirsize, cgsize;
  431         int avgifree, avgbfree, avgndir, curdirsize;
  432         int minifree, minbfree, maxndir;
  433         int mincg, minndir;
  434         int maxcontigdirs;
  435 
  436         mtx_assert(EXT2_MTX(pip->i_ump), MA_OWNED);
  437         fs = pip->i_e2fs;
  438 
  439         avgifree = fs->e2fs->e2fs_ficount / fs->e2fs_gcount;
  440         avgbfree = fs->e2fs->e2fs_fbcount / fs->e2fs_gcount;
  441         avgndir  = fs->e2fs_total_dir / fs->e2fs_gcount;
  442 
  443         /*
  444          * Force allocation in another cg if creating a first level dir.
  445          */
  446         ASSERT_VOP_LOCKED(ITOV(pip), "ext2fs_dirpref");
  447         if (ITOV(pip)->v_vflag & VV_ROOT) {
  448                 prefcg = arc4random() % fs->e2fs_gcount;
  449                 mincg = prefcg;
  450                 minndir = fs->e2fs_ipg;
  451                 for (cg = prefcg; cg < fs->e2fs_gcount; cg++)
  452                         if (fs->e2fs_gd[cg].ext2bgd_ndirs < minndir &&
  453                             fs->e2fs_gd[cg].ext2bgd_nifree >= avgifree &&
  454                             fs->e2fs_gd[cg].ext2bgd_nbfree >= avgbfree) {
  455                                 mincg = cg;
  456                                 minndir = fs->e2fs_gd[cg].ext2bgd_ndirs;
  457                         }
  458                 for (cg = 0; cg < prefcg; cg++)
  459                         if (fs->e2fs_gd[cg].ext2bgd_ndirs < minndir &&
  460                             fs->e2fs_gd[cg].ext2bgd_nifree >= avgifree &&
  461                             fs->e2fs_gd[cg].ext2bgd_nbfree >= avgbfree) {
  462                                 mincg = cg;
  463                                 minndir = fs->e2fs_gd[cg].ext2bgd_ndirs;
  464                         }
  465 
  466                 return (mincg);
  467         }
  468 
  469         /*
  470          * Count various limits which used for
  471          * optimal allocation of a directory inode.
  472          */
  473         maxndir = min(avgndir + fs->e2fs_ipg / 16, fs->e2fs_ipg);
  474         minifree = avgifree - avgifree / 4;
  475         if (minifree < 1)
  476                 minifree = 1;
  477         minbfree = avgbfree - avgbfree / 4;
  478         if (minbfree < 1)
  479                 minbfree = 1;
  480         cgsize = fs->e2fs_fsize * fs->e2fs_fpg;
  481         dirsize = AVGDIRSIZE;
  482         curdirsize = avgndir ? (cgsize - avgbfree * fs->e2fs_bsize) / avgndir : 0;
  483         if (dirsize < curdirsize)
  484                 dirsize = curdirsize;
  485         if (dirsize <= 0)
  486                 maxcontigdirs = 0;              /* dirsize overflowed */
  487         else
  488                 maxcontigdirs = min((avgbfree * fs->e2fs_bsize) / dirsize, 255);
  489         maxcontigdirs = min(maxcontigdirs, fs->e2fs_ipg / AFPDIR);
  490         if (maxcontigdirs == 0)
  491                 maxcontigdirs = 1;
  492 
  493         /*
  494          * Limit number of dirs in one cg and reserve space for 
  495          * regular files, but only if we have no deficit in
  496          * inodes or space.
  497          */
  498         prefcg = ino_to_cg(fs, pip->i_number);
  499         for (cg = prefcg; cg < fs->e2fs_gcount; cg++)
  500                 if (fs->e2fs_gd[cg].ext2bgd_ndirs < maxndir &&
  501                     fs->e2fs_gd[cg].ext2bgd_nifree >= minifree &&
  502                     fs->e2fs_gd[cg].ext2bgd_nbfree >= minbfree) {
  503                         if (fs->e2fs_contigdirs[cg] < maxcontigdirs)
  504                                 return (cg);
  505                 }
  506         for (cg = 0; cg < prefcg; cg++)
  507                 if (fs->e2fs_gd[cg].ext2bgd_ndirs < maxndir &&
  508                     fs->e2fs_gd[cg].ext2bgd_nifree >= minifree &&
  509                     fs->e2fs_gd[cg].ext2bgd_nbfree >= minbfree) {
  510                         if (fs->e2fs_contigdirs[cg] < maxcontigdirs)
  511                                 return (cg);
  512                 }
  513         /*
  514          * This is a backstop when we have deficit in space.
  515          */
  516         for (cg = prefcg; cg < fs->e2fs_gcount; cg++)
  517                 if (fs->e2fs_gd[cg].ext2bgd_nifree >= avgifree)
  518                         return (cg);
  519         for (cg = 0; cg < prefcg; cg++)
  520                 if (fs->e2fs_gd[cg].ext2bgd_nifree >= avgifree)
  521                         break;
  522         return (cg);
  523 }
  524 
  525 /*
  526  * Select the desired position for the next block in a file.  
  527  *
  528  * we try to mimic what Remy does in inode_getblk/block_getblk
  529  *
  530  * we note: blocknr == 0 means that we're about to allocate either
  531  * a direct block or a pointer block at the first level of indirection
  532  * (In other words, stuff that will go in i_db[] or i_ib[])
  533  *
  534  * blocknr != 0 means that we're allocating a block that is none
  535  * of the above. Then, blocknr tells us the number of the block
  536  * that will hold the pointer
  537  */
  538 int32_t
  539 ext2_blkpref(ip, lbn, indx, bap, blocknr)
  540         struct inode *ip;
  541         int32_t lbn;
  542         int indx;
  543         int32_t *bap;
  544         int32_t blocknr;
  545 {
  546         int     tmp;
  547         mtx_assert(EXT2_MTX(ip->i_ump), MA_OWNED);
  548 
  549         /* if the next block is actually what we thought it is,
  550            then set the goal to what we thought it should be
  551         */
  552         if(ip->i_next_alloc_block == lbn && ip->i_next_alloc_goal != 0)
  553                 return ip->i_next_alloc_goal;
  554 
  555         /* now check whether we were provided with an array that basically
  556            tells us previous blocks to which we want to stay closeby
  557         */
  558         if(bap) 
  559                 for (tmp = indx - 1; tmp >= 0; tmp--) 
  560                         if (bap[tmp]) 
  561                                 return bap[tmp];
  562 
  563         /* else let's fall back to the blocknr, or, if there is none,
  564            follow the rule that a block should be allocated near its inode
  565         */
  566         return blocknr ? blocknr :
  567                         (int32_t)(ip->i_block_group * 
  568                         EXT2_BLOCKS_PER_GROUP(ip->i_e2fs)) + 
  569                         ip->i_e2fs->e2fs->e2fs_first_dblock;
  570 }
  571 
  572 /*
  573  * Implement the cylinder overflow algorithm.
  574  *
  575  * The policy implemented by this algorithm is:
  576  *   1) allocate the block in its requested cylinder group.
  577  *   2) quadradically rehash on the cylinder group number.
  578  *   3) brute force search for a free block.
  579  */
  580 static u_long
  581 ext2_hashalloc(struct inode *ip, int cg, long pref, int size,
  582                 daddr_t (*allocator)(struct inode *, int, daddr_t, int))
  583 {
  584         struct m_ext2fs *fs;
  585         ino_t result;
  586         int i, icg = cg;
  587 
  588         mtx_assert(EXT2_MTX(ip->i_ump), MA_OWNED);
  589         fs = ip->i_e2fs;
  590         /*
  591          * 1: preferred cylinder group
  592          */
  593         result = (*allocator)(ip, cg, pref, size);
  594         if (result)
  595                 return (result);
  596         /*
  597          * 2: quadratic rehash
  598          */
  599         for (i = 1; i < fs->e2fs_gcount; i *= 2) {
  600                 cg += i;
  601                 if (cg >= fs->e2fs_gcount)
  602                         cg -= fs->e2fs_gcount;
  603                 result = (*allocator)(ip, cg, 0, size);
  604                 if (result)
  605                         return (result);
  606         }
  607         /*
  608          * 3: brute force search
  609          * Note that we start at i == 2, since 0 was checked initially,
  610          * and 1 is always checked in the quadratic rehash.
  611          */
  612         cg = (icg + 2) % fs->e2fs_gcount;
  613         for (i = 2; i < fs->e2fs_gcount; i++) {
  614                 result = (*allocator)(ip, cg, 0, size);
  615                 if (result)
  616                         return (result);
  617                 cg++;
  618                 if (cg == fs->e2fs_gcount)
  619                         cg = 0;
  620         }
  621         return (0);
  622 }
  623 
  624 /*
  625  * Determine whether a block can be allocated.
  626  *
  627  * Check to see if a block of the appropriate size is available,
  628  * and if it is, allocate it.
  629  */
  630 static daddr_t
  631 ext2_alloccg(struct inode *ip, int cg, daddr_t bpref, int size)
  632 {
  633         struct m_ext2fs *fs;
  634         struct buf *bp;
  635         struct ext2mount *ump;
  636         daddr_t bno, runstart, runlen;
  637         int bit, loc, end, error, start;
  638         char *bbp;
  639         /* XXX ondisk32 */
  640         fs = ip->i_e2fs;
  641         ump = ip->i_ump;
  642         if (fs->e2fs_gd[cg].ext2bgd_nbfree == 0)
  643                 return (0);
  644         EXT2_UNLOCK(ump);
  645         error = bread(ip->i_devvp, fsbtodb(fs,
  646                 fs->e2fs_gd[cg].ext2bgd_b_bitmap),
  647                 (int)fs->e2fs_bsize, NOCRED, &bp);
  648         if (error) {
  649                 brelse(bp);
  650                 EXT2_LOCK(ump);
  651                 return (0);
  652         }
  653         if (fs->e2fs_gd[cg].ext2bgd_nbfree == 0) {
  654                 /*
  655                  * Another thread allocated the last block in this
  656                  * group while we were waiting for the buffer.
  657                  */
  658                 brelse(bp);
  659                 EXT2_LOCK(ump);
  660                 return (0);
  661         }
  662         bbp = (char *)bp->b_data;
  663 
  664         if (dtog(fs, bpref) != cg)
  665                 bpref = 0;
  666         if (bpref != 0) {
  667                 bpref = dtogd(fs, bpref);
  668                 /*
  669                  * if the requested block is available, use it
  670                  */
  671                 if (isclr(bbp, bpref)) {
  672                         bno = bpref;
  673                         goto gotit;
  674                 }
  675         }
  676         /*
  677          * no blocks in the requested cylinder, so take next
  678          * available one in this cylinder group.
  679          * first try to get 8 contigous blocks, then fall back to a single
  680          * block.
  681          */
  682         if (bpref)
  683                 start = dtogd(fs, bpref) / NBBY;
  684         else
  685                 start = 0;
  686         end = howmany(fs->e2fs->e2fs_fpg, NBBY) - start;
  687 retry:
  688         runlen = 0;
  689         runstart = 0;
  690         for (loc = start; loc < end; loc++) {
  691                 if (bbp[loc] == (char)0xff) {
  692                         runlen = 0;
  693                         continue;
  694                 }
  695 
  696                 /* Start of a run, find the number of high clear bits. */
  697                 if (runlen == 0) {
  698                         bit = fls(bbp[loc]);
  699                         runlen = NBBY - bit;
  700                         runstart = loc * NBBY + bit;
  701                 } else if (bbp[loc] == 0) {
  702                         /* Continue a run. */
  703                         runlen += NBBY;
  704                 } else {
  705                         /*
  706                          * Finish the current run.  If it isn't long
  707                          * enough, start a new one.
  708                          */
  709                         bit = ffs(bbp[loc]) - 1;
  710                         runlen += bit;
  711                         if (runlen >= 8) {
  712                                 bno = runstart;
  713                                 goto gotit;
  714                         }
  715 
  716                         /* Run was too short, start a new one. */
  717                         bit = fls(bbp[loc]);
  718                         runlen = NBBY - bit;
  719                         runstart = loc * NBBY + bit;
  720                 }
  721 
  722                 /* If the current run is long enough, use it. */
  723                 if (runlen >= 8) {
  724                         bno = runstart;
  725                         goto gotit;
  726                 }
  727         }
  728         if (start != 0) {
  729                 end = start;
  730                 start = 0;
  731                 goto retry;
  732         }
  733 
  734         bno = ext2_mapsearch(fs, bbp, bpref);
  735         if (bno < 0){
  736                 brelse(bp);
  737                 EXT2_LOCK(ump);
  738                 return (0);
  739         }
  740 gotit:
  741 #ifdef DIAGNOSTIC
  742         if (isset(bbp, bno)) {
  743                 printf("ext2fs_alloccgblk: cg=%d bno=%jd fs=%s\n",
  744                         cg, (intmax_t)bno, fs->e2fs_fsmnt);
  745                 panic("ext2fs_alloccg: dup alloc");
  746         }
  747 #endif
  748         setbit(bbp, bno);
  749         EXT2_LOCK(ump);
  750         fs->e2fs->e2fs_fbcount--;
  751         fs->e2fs_gd[cg].ext2bgd_nbfree--;
  752         fs->e2fs_fmod = 1;
  753         EXT2_UNLOCK(ump);
  754         bdwrite(bp);
  755         return (cg * fs->e2fs->e2fs_fpg + fs->e2fs->e2fs_first_dblock + bno);
  756 }
  757 
  758 /*
  759  * Determine whether an inode can be allocated.
  760  *
  761  * Check to see if an inode is available, and if it is,
  762  * allocate it using tode in the specified cylinder group.
  763  */
  764 static daddr_t
  765 ext2_nodealloccg(struct inode *ip, int cg, daddr_t ipref, int mode)
  766 {
  767         struct m_ext2fs *fs;
  768         struct buf *bp;
  769         struct ext2mount *ump;
  770         int error, start, len, loc, map, i;
  771         char *ibp;
  772         ipref--; /* to avoid a lot of (ipref -1) */
  773         if (ipref == -1)
  774                 ipref = 0;
  775         fs = ip->i_e2fs;
  776         ump = ip->i_ump;
  777         if (fs->e2fs_gd[cg].ext2bgd_nifree == 0)
  778                 return (0);
  779         EXT2_UNLOCK(ump);       
  780         error = bread(ip->i_devvp, fsbtodb(fs,
  781                 fs->e2fs_gd[cg].ext2bgd_i_bitmap),
  782                 (int)fs->e2fs_bsize, NOCRED, &bp);
  783         if (error) {
  784                 brelse(bp);
  785                 EXT2_LOCK(ump);
  786                 return (0);
  787         }
  788         if (fs->e2fs_gd[cg].ext2bgd_nifree == 0) {
  789                 /*
  790                  * Another thread allocated the last i-node in this
  791                  * group while we were waiting for the buffer.
  792                  */
  793                 brelse(bp);
  794                 EXT2_LOCK(ump);
  795                 return (0);
  796         }
  797         ibp = (char *)bp->b_data;
  798         if (ipref) {
  799                 ipref %= fs->e2fs->e2fs_ipg;
  800                 if (isclr(ibp, ipref))
  801                         goto gotit;
  802         }
  803         start = ipref / NBBY;
  804         len = howmany(fs->e2fs->e2fs_ipg - ipref, NBBY);
  805         loc = skpc(0xff, len, &ibp[start]);
  806         if (loc == 0) {
  807                 len = start + 1;
  808                 start = 0;
  809                 loc = skpc(0xff, len, &ibp[0]);
  810                 if (loc == 0) {
  811                         printf("cg = %d, ipref = %lld, fs = %s\n",
  812                                 cg, (long long)ipref, fs->e2fs_fsmnt);
  813                         panic("ext2fs_nodealloccg: map corrupted");
  814                         /* NOTREACHED */
  815                 }
  816         } 
  817         i = start + len - loc;
  818         map = ibp[i] ^ 0xff;
  819         if (map == 0) {
  820                 printf("fs = %s\n", fs->e2fs_fsmnt);
  821                 panic("ext2fs_nodealloccg: block not in map");
  822         }
  823         ipref = i * NBBY + ffs(map) - 1;
  824 gotit:
  825         setbit(ibp, ipref);
  826         EXT2_LOCK(ump);
  827         fs->e2fs_gd[cg].ext2bgd_nifree--;
  828         fs->e2fs->e2fs_ficount--;
  829         fs->e2fs_fmod = 1;
  830         if ((mode & IFMT) == IFDIR) {
  831                 fs->e2fs_gd[cg].ext2bgd_ndirs++;
  832                 fs->e2fs_total_dir++;
  833         }
  834         EXT2_UNLOCK(ump);
  835         bdwrite(bp);
  836         return (cg * fs->e2fs->e2fs_ipg + ipref +1);
  837 }
  838 
  839 /*
  840  * Free a block or fragment.
  841  *
  842  */
  843 void
  844 ext2_blkfree(ip, bno, size)
  845         struct inode *ip;
  846         int32_t bno;
  847         long size;
  848 {
  849         struct m_ext2fs *fs;
  850         struct buf *bp;
  851         struct ext2mount *ump;
  852         int cg, error;
  853         char *bbp;
  854 
  855         fs = ip->i_e2fs;
  856         ump = ip->i_ump;
  857         cg = dtog(fs, bno);
  858         if ((u_int)bno >= fs->e2fs->e2fs_bcount) {
  859                 printf("bad block %lld, ino %llu\n", (long long)bno,
  860                     (unsigned long long)ip->i_number);
  861                 ext2_fserr(fs, ip->i_uid, "bad block");
  862                 return;
  863         }
  864         error = bread(ip->i_devvp,
  865                 fsbtodb(fs, fs->e2fs_gd[cg].ext2bgd_b_bitmap),
  866                 (int)fs->e2fs_bsize, NOCRED, &bp);
  867         if (error) {
  868                 brelse(bp);
  869                 return;
  870         }
  871         bbp = (char *)bp->b_data;
  872         bno = dtogd(fs, bno);
  873         if (isclr(bbp, bno)) {
  874                 printf("block = %lld, fs = %s\n",
  875                      (long long)bno, fs->e2fs_fsmnt);
  876                 panic("blkfree: freeing free block");
  877         }
  878         clrbit(bbp, bno);
  879         EXT2_LOCK(ump);
  880         fs->e2fs->e2fs_fbcount++;
  881         fs->e2fs_gd[cg].ext2bgd_nbfree++;
  882         fs->e2fs_fmod = 1;
  883         EXT2_UNLOCK(ump);
  884         bdwrite(bp);
  885 }
  886 
  887 /*
  888  * Free an inode.
  889  *
  890  */
  891 int
  892 ext2_vfree(pvp, ino, mode)
  893         struct vnode *pvp;
  894         ino_t ino;
  895         int mode;
  896 {
  897         struct m_ext2fs *fs;
  898         struct inode *pip;
  899         struct buf *bp;
  900         struct ext2mount *ump;
  901         int error, cg;
  902         char * ibp;
  903 /*      mode_t save_i_mode; */
  904 
  905         pip = VTOI(pvp);
  906         fs = pip->i_e2fs;
  907         ump = pip->i_ump;
  908         if ((u_int)ino > fs->e2fs_ipg * fs->e2fs_gcount)
  909                 panic("ext2_vfree: range: devvp = %p, ino = %d, fs = %s",
  910                     pip->i_devvp, ino, fs->e2fs_fsmnt);
  911 
  912         cg = ino_to_cg(fs, ino);
  913         error = bread(pip->i_devvp,
  914                 fsbtodb(fs, fs->e2fs_gd[cg].ext2bgd_i_bitmap),
  915                 (int)fs->e2fs_bsize, NOCRED, &bp);
  916         if (error) {
  917                 brelse(bp);
  918                 return (0);
  919         }
  920         ibp = (char *)bp->b_data;
  921         ino = (ino - 1) % fs->e2fs->e2fs_ipg;
  922         if (isclr(ibp, ino)) {
  923                 printf("ino = %llu, fs = %s\n",
  924                          (unsigned long long)ino, fs->e2fs_fsmnt);
  925                 if (fs->e2fs_ronly == 0)
  926                         panic("ifree: freeing free inode");
  927         }
  928         clrbit(ibp, ino);
  929         EXT2_LOCK(ump);
  930         fs->e2fs->e2fs_ficount++;
  931         fs->e2fs_gd[cg].ext2bgd_nifree++;
  932         if ((mode & IFMT) == IFDIR) {
  933                 fs->e2fs_gd[cg].ext2bgd_ndirs--;
  934                 fs->e2fs_total_dir--;
  935         }
  936         fs->e2fs_fmod = 1;
  937         EXT2_UNLOCK(ump);
  938         bdwrite(bp);
  939         return (0);
  940 }
  941 
  942 /*
  943  * Find a block in the specified cylinder group.
  944  *
  945  * It is a panic if a request is made to find a block if none are
  946  * available.
  947  */
  948 static daddr_t
  949 ext2_mapsearch(struct m_ext2fs *fs, char *bbp, daddr_t bpref)
  950 {
  951         int start, len, loc, i, map;
  952 
  953         /*
  954          * find the fragment by searching through the free block
  955          * map for an appropriate bit pattern
  956          */
  957         if (bpref)
  958                 start = dtogd(fs, bpref) / NBBY;
  959         else
  960                 start = 0;
  961         len = howmany(fs->e2fs->e2fs_fpg, NBBY) - start;
  962         loc = skpc(0xff, len, &bbp[start]);
  963         if (loc == 0) {
  964                 len = start + 1;
  965                 start = 0;
  966                 loc = skpc(0xff, len, &bbp[start]);
  967                 if (loc == 0) {
  968                         printf("start = %d, len = %d, fs = %s\n",
  969                                 start, len, fs->e2fs_fsmnt);
  970                         panic("ext2fs_alloccg: map corrupted");
  971                         /* NOTREACHED */
  972                 }
  973         }
  974         i = start + len - loc;
  975         map = bbp[i] ^ 0xff;
  976         if (map == 0) {
  977                 printf("fs = %s\n", fs->e2fs_fsmnt);
  978                 panic("ext2fs_mapsearch: block not in map");
  979         }
  980         return (i * NBBY + ffs(map) - 1);
  981 }
  982 
  983 /*
  984  * Fserr prints the name of a file system with an error diagnostic.
  985  * 
  986  * The form of the error message is:
  987  *      fs: error message
  988  */
  989 static void
  990 ext2_fserr(fs, uid, cp)
  991         struct m_ext2fs *fs;
  992         uid_t uid;
  993         char *cp;
  994 {
  995 
  996         log(LOG_ERR, "uid %u on %s: %s\n", uid, fs->e2fs_fsmnt, cp);
  997 }
  998 
  999 int
 1000 cg_has_sb(int i)
 1001 {
 1002         int a3, a5, a7;
 1003 
 1004         if (i == 0 || i == 1)
 1005                 return 1;
 1006         for (a3 = 3, a5 = 5, a7 = 7;
 1007             a3 <= i || a5 <= i || a7 <= i;
 1008             a3 *= 3, a5 *= 5, a7 *= 7)
 1009                 if (i == a3 || i == a5 || i == a7)
 1010                         return 1;
 1011         return 0;
 1012 }

Cache object: 41d6774ec28080146b887dc33c7d25b5


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