linux/fs/reiserfs/objectid.c
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   1/*
   2 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
   3 */
   4
   5#include <linux/string.h>
   6#include <linux/time.h>
   7#include <linux/uuid.h>
   8#include "reiserfs.h"
   9
  10/* find where objectid map starts */
  11#define objectid_map(s,rs) (old_format_only (s) ? \
  12                         (__le32 *)((struct reiserfs_super_block_v1 *)(rs) + 1) :\
  13                         (__le32 *)((rs) + 1))
  14
  15#ifdef CONFIG_REISERFS_CHECK
  16
  17static void check_objectid_map(struct super_block *s, __le32 * map)
  18{
  19        if (le32_to_cpu(map[0]) != 1)
  20                reiserfs_panic(s, "vs-15010", "map corrupted: %lx",
  21                               (long unsigned int)le32_to_cpu(map[0]));
  22
  23        /* FIXME: add something else here */
  24}
  25
  26#else
  27static void check_objectid_map(struct super_block *s, __le32 * map)
  28{;
  29}
  30#endif
  31
  32/*
  33 * When we allocate objectids we allocate the first unused objectid.
  34 * Each sequence of objectids in use (the odd sequences) is followed
  35 * by a sequence of objectids not in use (the even sequences).  We
  36 * only need to record the last objectid in each of these sequences
  37 * (both the odd and even sequences) in order to fully define the
  38 * boundaries of the sequences.  A consequence of allocating the first
  39 * objectid not in use is that under most conditions this scheme is
  40 * extremely compact.  The exception is immediately after a sequence
  41 * of operations which deletes a large number of objects of
  42 * non-sequential objectids, and even then it will become compact
  43 * again as soon as more objects are created.  Note that many
  44 * interesting optimizations of layout could result from complicating
  45 * objectid assignment, but we have deferred making them for now.
  46 */
  47
  48/* get unique object identifier */
  49__u32 reiserfs_get_unused_objectid(struct reiserfs_transaction_handle *th)
  50{
  51        struct super_block *s = th->t_super;
  52        struct reiserfs_super_block *rs = SB_DISK_SUPER_BLOCK(s);
  53        __le32 *map = objectid_map(s, rs);
  54        __u32 unused_objectid;
  55
  56        BUG_ON(!th->t_trans_id);
  57
  58        check_objectid_map(s, map);
  59
  60        reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
  61        /* comment needed -Hans */
  62        unused_objectid = le32_to_cpu(map[1]);
  63        if (unused_objectid == U32_MAX) {
  64                reiserfs_warning(s, "reiserfs-15100", "no more object ids");
  65                reiserfs_restore_prepared_buffer(s, SB_BUFFER_WITH_SB(s));
  66                return 0;
  67        }
  68
  69        /*
  70         * This incrementation allocates the first unused objectid. That
  71         * is to say, the first entry on the objectid map is the first
  72         * unused objectid, and by incrementing it we use it.  See below
  73         * where we check to see if we eliminated a sequence of unused
  74         * objectids....
  75         */
  76        map[1] = cpu_to_le32(unused_objectid + 1);
  77
  78        /*
  79         * Now we check to see if we eliminated the last remaining member of
  80         * the first even sequence (and can eliminate the sequence by
  81         * eliminating its last objectid from oids), and can collapse the
  82         * first two odd sequences into one sequence.  If so, then the net
  83         * result is to eliminate a pair of objectids from oids.  We do this
  84         * by shifting the entire map to the left.
  85         */
  86        if (sb_oid_cursize(rs) > 2 && map[1] == map[2]) {
  87                memmove(map + 1, map + 3,
  88                        (sb_oid_cursize(rs) - 3) * sizeof(__u32));
  89                set_sb_oid_cursize(rs, sb_oid_cursize(rs) - 2);
  90        }
  91
  92        journal_mark_dirty(th, SB_BUFFER_WITH_SB(s));
  93        return unused_objectid;
  94}
  95
  96/* makes object identifier unused */
  97void reiserfs_release_objectid(struct reiserfs_transaction_handle *th,
  98                               __u32 objectid_to_release)
  99{
 100        struct super_block *s = th->t_super;
 101        struct reiserfs_super_block *rs = SB_DISK_SUPER_BLOCK(s);
 102        __le32 *map = objectid_map(s, rs);
 103        int i = 0;
 104
 105        BUG_ON(!th->t_trans_id);
 106        /*return; */
 107        check_objectid_map(s, map);
 108
 109        reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
 110        journal_mark_dirty(th, SB_BUFFER_WITH_SB(s));
 111
 112        /*
 113         * start at the beginning of the objectid map (i = 0) and go to
 114         * the end of it (i = disk_sb->s_oid_cursize).  Linear search is
 115         * what we use, though it is possible that binary search would be
 116         * more efficient after performing lots of deletions (which is
 117         * when oids is large.)  We only check even i's.
 118         */
 119        while (i < sb_oid_cursize(rs)) {
 120                if (objectid_to_release == le32_to_cpu(map[i])) {
 121                        /* This incrementation unallocates the objectid. */
 122                        le32_add_cpu(&map[i], 1);
 123
 124                        /*
 125                         * Did we unallocate the last member of an
 126                         * odd sequence, and can shrink oids?
 127                         */
 128                        if (map[i] == map[i + 1]) {
 129                                /* shrink objectid map */
 130                                memmove(map + i, map + i + 2,
 131                                        (sb_oid_cursize(rs) - i -
 132                                         2) * sizeof(__u32));
 133                                set_sb_oid_cursize(rs, sb_oid_cursize(rs) - 2);
 134
 135                                RFALSE(sb_oid_cursize(rs) < 2 ||
 136                                       sb_oid_cursize(rs) > sb_oid_maxsize(rs),
 137                                       "vs-15005: objectid map corrupted cur_size == %d (max == %d)",
 138                                       sb_oid_cursize(rs), sb_oid_maxsize(rs));
 139                        }
 140                        return;
 141                }
 142
 143                if (objectid_to_release > le32_to_cpu(map[i]) &&
 144                    objectid_to_release < le32_to_cpu(map[i + 1])) {
 145                        /* size of objectid map is not changed */
 146                        if (objectid_to_release + 1 == le32_to_cpu(map[i + 1])) {
 147                                le32_add_cpu(&map[i + 1], -1);
 148                                return;
 149                        }
 150
 151                        /*
 152                         * JDM comparing two little-endian values for
 153                         * equality -- safe
 154                         */
 155                        /*
 156                         * objectid map must be expanded, but
 157                         * there is no space
 158                         */
 159                        if (sb_oid_cursize(rs) == sb_oid_maxsize(rs)) {
 160                                PROC_INFO_INC(s, leaked_oid);
 161                                return;
 162                        }
 163
 164                        /* expand the objectid map */
 165                        memmove(map + i + 3, map + i + 1,
 166                                (sb_oid_cursize(rs) - i - 1) * sizeof(__u32));
 167                        map[i + 1] = cpu_to_le32(objectid_to_release);
 168                        map[i + 2] = cpu_to_le32(objectid_to_release + 1);
 169                        set_sb_oid_cursize(rs, sb_oid_cursize(rs) + 2);
 170                        return;
 171                }
 172                i += 2;
 173        }
 174
 175        reiserfs_error(s, "vs-15011", "tried to free free object id (%lu)",
 176                       (long unsigned)objectid_to_release);
 177}
 178
 179int reiserfs_convert_objectid_map_v1(struct super_block *s)
 180{
 181        struct reiserfs_super_block *disk_sb = SB_DISK_SUPER_BLOCK(s);
 182        int cur_size = sb_oid_cursize(disk_sb);
 183        int new_size = (s->s_blocksize - SB_SIZE) / sizeof(__u32) / 2 * 2;
 184        int old_max = sb_oid_maxsize(disk_sb);
 185        struct reiserfs_super_block_v1 *disk_sb_v1;
 186        __le32 *objectid_map;
 187        int i;
 188
 189        disk_sb_v1 =
 190            (struct reiserfs_super_block_v1 *)(SB_BUFFER_WITH_SB(s)->b_data);
 191        objectid_map = (__le32 *) (disk_sb_v1 + 1);
 192
 193        if (cur_size > new_size) {
 194                /*
 195                 * mark everyone used that was listed as free at
 196                 * the end of the objectid map
 197                 */
 198                objectid_map[new_size - 1] = objectid_map[cur_size - 1];
 199                set_sb_oid_cursize(disk_sb, new_size);
 200        }
 201        /* move the smaller objectid map past the end of the new super */
 202        for (i = new_size - 1; i >= 0; i--) {
 203                objectid_map[i + (old_max - new_size)] = objectid_map[i];
 204        }
 205
 206        /* set the max size so we don't overflow later */
 207        set_sb_oid_maxsize(disk_sb, new_size);
 208
 209        /* Zero out label and generate random UUID */
 210        memset(disk_sb->s_label, 0, sizeof(disk_sb->s_label));
 211        generate_random_uuid(disk_sb->s_uuid);
 212
 213        /* finally, zero out the unused chunk of the new super */
 214        memset(disk_sb->s_unused, 0, sizeof(disk_sb->s_unused));
 215        return 0;
 216}
 217