fs/reiserfs/objectid.c

   1 /*
   2  * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
   3  */
   4
   5 #include <linux/string.h>
   6 #include <linux/random.h>
   7 #include <linux/time.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
  17 static 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
  27 static 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 */
  97 void 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
 179 int 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, *new_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         new_objectid_map = (__le32 *) (disk_sb + 1);
 193
 194         if (cur_size > new_size) {
 195                 /*
 196                  * mark everyone used that was listed as free at
 197                  * the end of the objectid map
 198                  */
 199                 objectid_map[new_size - 1] = objectid_map[cur_size - 1];
 200                 set_sb_oid_cursize(disk_sb, new_size);
 201         }
 202         /* move the smaller objectid map past the end of the new super */
 203         for (i = new_size - 1; i >= 0; i--) {
 204                 objectid_map[i + (old_max - new_size)] = objectid_map[i];
 205         }
 206
 207         /* set the max size so we don't overflow later */
 208         set_sb_oid_maxsize(disk_sb, new_size);
 209
 210         /* Zero out label and generate random UUID */
 211         memset(disk_sb->s_label, 0, sizeof(disk_sb->s_label));
 212         generate_random_uuid(disk_sb->s_uuid);
 213
 214         /* finally, zero out the unused chunk of the new super */
 215         memset(disk_sb->s_unused, 0, sizeof(disk_sb->s_unused));
 216         return 0;
 217 }