fs/reiserfs/objectid.c

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