fs/hfs/hfs_btree.h

   1 /*
   2  * linux/fs/hfs/hfs_btree.h
   3  *
   4  * Copyright (C) 1995-1997  Paul H. Hargrove
   5  * This file may be distributed under the terms of the GNU Public License.
   6  *
   7  * This file contains the declarations of the private B-tree
   8  * structures and functions.
   9  *
  10  * "XXX" in a comment is a note to myself to consider changing something.
  11  */
  12
  13 #ifndef _HFS_BTREE_H
  14 #define _HFS_BTREE_H
  15
  16 #include "hfs.h"
  17
  18 /*================ Variable-like macros ================*/
  19
  20 /* The stickiness of a (struct hfs_bnode) */
  21 #define HFS_NOT_STICKY  0
  22 #define HFS_STICKY      1
  23
  24 /* The number of hash buckets in a B-tree's bnode cache */
  25 #define HFS_CACHELEN    17      /* primes are best? */
  26
  27 /*
  28  * Legal values for the 'ndType' field of a (struct NodeDescriptor)
  29  *
  30  * Reference: _Inside Macintosh: Files_ p. 2-65
  31  */
  32 #define ndIndxNode      0x00    /* An internal (index) node */
  33 #define ndHdrNode       0x01    /* The tree header node (node 0) */
  34 #define ndMapNode       0x02    /* Holds part of the bitmap of used nodes */
  35 #define ndLeafNode      0xFF    /* A leaf (ndNHeight==1) node */
  36
  37 /*================ Function-like macros ================*/
  38
  39 /* Access the cache slot which should contain the desired node */
  40 #define bhash(tree, node) ((tree)->cache[(node) % HFS_CACHELEN])
  41
  42 /* round up to multiple of sizeof(hfs_u16) */
  43 #define ROUND(X) ((X + sizeof(hfs_u16) - 1) & ~(sizeof(hfs_u16)-1))
  44
  45 /* Refer to the (base-1) array of offsets in a bnode */
  46 #define RECTBL(X,N) \
  47         (((hfs_u16 *)(hfs_buffer_data((X)->buf)+HFS_SECTOR_SIZE))-(N))
  48
  49 /*================ Private data types ================*/
  50
  51 /*
  52  * struct BTHdrRec
  53  *
  54  * The B-tree header record
  55  *
  56  * This data structure is stored in the first node (512-byte block) of
  57  * each B-tree file.  It contains important information about the
  58  * B-tree.  Most fields vary over the life of the tree and are
  59  * indicated by a 'V' in the comments.  The other fields are fixed for
  60  * the life of the tree and are indicated by a 'F'.
  61  *
  62  * Reference: _Inside Macintosh: Files_ pp. 2-68 through 2-69 */
  63 struct BTHdrRec {
  64         hfs_word_t  bthDepth;   /* (V) The number of levels in this B-tree */
  65         hfs_lword_t bthRoot;    /* (V) The node number of the root node */
  66         hfs_lword_t bthNRecs;   /* (V) The number of leaf records */
  67         hfs_lword_t bthFNode;   /* (V) The number of the first leaf node */
  68         hfs_lword_t bthLNode;   /* (V) The number of the last leaf node */
  69         hfs_word_t  bthNodeSize;        /* (F) The number of bytes in a node (=512) */
  70         hfs_word_t  bthKeyLen;  /* (F) The length of a key in an index node */
  71         hfs_lword_t bthNNodes;  /* (V) The total number of nodes */
  72         hfs_lword_t bthFree;    /* (V) The number of unused nodes */
  73         hfs_byte_t  bthResv[76];        /* Reserved */
  74 };
  75
  76 /*
  77  * struct NodeDescriptor
  78  *
  79  * The B-tree node descriptor.
  80  *
  81  * This structure begins each node in the B-tree file.  It contains
  82  * important information about the node's contents.  'V' and 'F' in
  83  * the comments indicate fields that are variable or fixed over the
  84  * life of a node, where the 'life' of a node is defined as the period
  85  * between leaving and reentering the free pool.
  86  *
  87  * Reference: _Inside Macintosh: Files_ p. 2-64
  88  */
  89 struct NodeDescriptor {
  90         hfs_lword_t ndFLink;    /* (V) Number of the next node at this level */
  91         hfs_lword_t ndBLink;    /* (V) Number of the prev node at this level */
  92         hfs_byte_t  ndType;     /* (F) The type of node */
  93         hfs_byte_t  ndNHeight;  /* (F) The level of this node (leaves=1) */
  94         hfs_word_t  ndNRecs;    /* (V) The number of records in this node */
  95         hfs_word_t  ndResv2;    /* Reserved */
  96 };
  97
  98 /*
  99  * typedef hfs_cmpfn
 100  *
 101  * The type 'hfs_cmpfn' is a comparison function taking 2 keys and
 102  * returning a positive, negative or zero integer according to the
 103  * ordering of the two keys (just like strcmp() does for strings).
 104  */
 105 typedef int (*hfs_cmpfn)(const void *, const void *);
 106
 107 /*
 108  * struct hfs_bnode
 109  *
 110  * An in-core B-tree node
 111  *
 112  * This structure holds information from the NodeDescriptor in native
 113  * byte-order, a pointer to the buffer which contains the actual
 114  * node and fields necessary for locking access to the node during
 115  * updates.  The use of the locking fields is explained with the
 116  * locking functions.
 117  */
 118 struct hfs_bnode {
 119         int                 magic;   /* Magic number to guard against
 120                                         wild pointers */
 121         hfs_buffer          buf;     /* The buffer containing the
 122                                         actual node */
 123         struct hfs_btree    *tree;   /* The tree to which this node
 124                                         belongs */
 125         struct hfs_bnode    *prev;   /* Next node in this hash bucket */
 126         struct hfs_bnode    *next;   /* Previous node in this hash
 127                                         bucket */
 128         int                 sticky;  /* Boolean: non-zero means keep
 129                                         this node in-core (set for
 130                                         root and head) */
 131         hfs_u32             node;    /* Node number */
 132         /* locking related fields: */
 133         hfs_wait_queue      wqueue;  /* Wait queue for write access */
 134         hfs_wait_queue      rqueue;  /* Wait queue for read or reserve
 135                                         access */
 136         int                 count;   /* Number of processes accessing
 137                                         this node */
 138         int                 resrv;   /* Boolean, true means a process
 139                                         had placed a 'reservation' on
 140                                         this node */
 141         int                 lock;    /* Boolean, true means some
 142                                         process has exclusive access,
 143                                         so KEEP OUT */
 144         /* fields from the NodeDescriptor in native byte-order: */
 145         hfs_u32             ndFLink;
 146         hfs_u32             ndBLink;
 147         hfs_u16             ndNRecs;
 148         hfs_u8              ndType;
 149         hfs_u8              ndNHeight;
 150 };
 151
 152 /*
 153  * struct hfs_btree
 154  *
 155  * An in-core B-tree.
 156  *
 157  * This structure holds information from the BTHdrRec, MDB
 158  * (superblock) and other information needed to work with the B-tree.
 159  */
 160 struct hfs_btree {
 161         int                     magic;         /* Magic number to
 162                                                   guard against wild
 163                                                   pointers */
 164         hfs_cmpfn               compare;       /* Comparison function
 165                                                   for this tree */
 166         struct hfs_bnode        head;          /* in-core copy of node 0 */
 167         struct hfs_bnode        *root;         /* Pointer to the in-core
 168                                                   copy of the root node */
 169         hfs_sysmdb              sys_mdb;       /* The "device" holding
 170                                                   the filesystem */
 171         int                     reserved;      /* bnodes claimed but
 172                                                   not yet used */
 173         struct hfs_bnode                       /* The bnode cache */
 174                                 *cache[HFS_CACHELEN];
 175         struct hfs_cat_entry    entry;         /* Fake catalog entry */
 176         int                     lock;
 177         hfs_wait_queue          wait;
 178         int                     dirt;
 179         /* Fields from the BTHdrRec in native byte-order: */
 180         hfs_u32                 bthRoot;
 181         hfs_u32                 bthNRecs;
 182         hfs_u32                 bthFNode;
 183         hfs_u32                 bthLNode;
 184         hfs_u32                 bthNNodes;
 185         hfs_u32                 bthFree;
 186         hfs_u16                 bthKeyLen;
 187         hfs_u16                 bthDepth;
 188 };
 189
 190 /*================ Global functions ================*/
 191
 192 /* Convert a (struct hfs_bnode *) and an index to the value of the
 193    n-th offset in the bnode (N >= 1) to the offset */
 194 extern inline hfs_u16 bnode_offset(const struct hfs_bnode *bnode, int n)
 195 { return hfs_get_hs(RECTBL(bnode,n)); }
 196
 197 /* Convert a (struct hfs_bnode *) and an index to the size of the
 198    n-th record in the bnode (N >= 1) */
 199 extern inline hfs_u16 bnode_rsize(const struct hfs_bnode *bnode, int n)
 200 { return bnode_offset(bnode, n+1) - bnode_offset(bnode, n); }
 201
 202 /* Convert a (struct hfs_bnode *) to the offset of the empty part */
 203 extern inline hfs_u16 bnode_end(const struct hfs_bnode *bnode)
 204 { return bnode_offset(bnode, bnode->ndNRecs + 1); }
 205
 206 /* Convert a (struct hfs_bnode *) to the number of free bytes it contains */
 207 extern inline hfs_u16 bnode_freespace(const struct hfs_bnode *bnode)
 208 { return HFS_SECTOR_SIZE - bnode_end(bnode)
 209           - (bnode->ndNRecs + 1)*sizeof(hfs_u16); }
 210
 211 /* Convert a (struct hfs_bnode *) X and an index N to
 212    the address of the record N in the bnode (N >= 1) */
 213 extern inline void *bnode_datastart(const struct hfs_bnode *bnode)
 214 { return (void *)(hfs_buffer_data(bnode->buf)+sizeof(struct NodeDescriptor)); }
 215
 216 /* Convert a (struct hfs_bnode *) to the address of the empty part */
 217 extern inline void *bnode_dataend(const struct hfs_bnode *bnode)
 218 { return (void *)(hfs_buffer_data(bnode->buf) + bnode_end(bnode)); }
 219
 220 /* Convert various pointers to address of record's key */
 221 extern inline void *bnode_key(const struct hfs_bnode *bnode, int n)
 222 { return (void *)(hfs_buffer_data(bnode->buf) + bnode_offset(bnode, n)); }
 223 extern inline void *belem_key(const struct hfs_belem *elem)
 224 { return bnode_key(elem->bnr.bn, elem->record); }
 225 extern inline void *brec_key(const struct hfs_brec *brec)
 226 { return belem_key(brec->bottom); }
 227
 228 /* Convert various pointers to the address of a record */
 229 extern inline void *bkey_record(const struct hfs_bkey *key)
 230 { return (void *)key + ROUND(key->KeyLen + 1); }
 231 extern inline void *bnode_record(const struct hfs_bnode *bnode, int n)
 232 { return bkey_record(bnode_key(bnode, n)); }
 233 extern inline void *belem_record(const struct hfs_belem *elem)
 234 { return bkey_record(belem_key(elem)); }
 235 extern inline void *brec_record(const struct hfs_brec *brec)
 236 { return bkey_record(brec_key(brec)); }
 237
 238 /*================ Function Prototypes ================*/
 239
 240 /* balloc.c */
 241 extern int hfs_bnode_bitop(struct hfs_btree *, hfs_u32, int);
 242 extern struct hfs_bnode_ref hfs_bnode_alloc(struct hfs_btree *);
 243 extern int hfs_bnode_free(struct hfs_bnode_ref *);
 244 extern void hfs_btree_extend(struct hfs_btree *);
 245
 246 /* bins_del.c */
 247 extern void hfs_bnode_update_key(struct hfs_brec *, struct hfs_belem *,
 248                                  struct hfs_bnode *, int);
 249 extern void hfs_bnode_shift_right(struct hfs_bnode *, struct hfs_bnode *, int);
 250 extern void hfs_bnode_shift_left(struct hfs_bnode *, struct hfs_bnode *, int);
 251 extern int hfs_bnode_in_brec(hfs_u32 node, const struct hfs_brec *brec);
 252
 253 /* bnode.c */
 254 extern void hfs_bnode_read(struct hfs_bnode *, struct hfs_btree *,
 255                            hfs_u32, int);
 256 extern void hfs_bnode_relse(struct hfs_bnode_ref *);
 257 extern struct hfs_bnode_ref hfs_bnode_find(struct hfs_btree *, hfs_u32, int);
 258 extern void hfs_bnode_lock(struct hfs_bnode_ref *, int);
 259 extern void hfs_bnode_delete(struct hfs_bnode *);
 260 extern void hfs_bnode_commit(struct hfs_bnode *);
 261
 262 /* brec.c */
 263 extern void hfs_brec_lock(struct hfs_brec *, struct hfs_belem *);
 264 extern struct hfs_belem *hfs_brec_init(struct hfs_brec *, struct hfs_btree *,
 265                                        int);
 266 extern struct hfs_belem *hfs_brec_next(struct hfs_brec *);
 267
 268 #endif