fs/xfs/xfs_dir_leaf.h

   1 /*
   2  * Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #ifndef __XFS_DIR_LEAF_H__
  19 #define __XFS_DIR_LEAF_H__
  20
  21 /*
  22  * Directory layout, internal structure, access macros, etc.
  23  *
  24  * Large directories are structured around Btrees where all the data
  25  * elements are in the leaf nodes.  Filenames are hashed into an int,
  26  * then that int is used as the index into the Btree.  Since the hashval
  27  * of a filename may not be unique, we may have duplicate keys.  The
  28  * internal links in the Btree are logical block offsets into the file.
  29  */
  30
  31 struct uio;
  32 struct xfs_bmap_free;
  33 struct xfs_dabuf;
  34 struct xfs_da_args;
  35 struct xfs_da_state;
  36 struct xfs_da_state_blk;
  37 struct xfs_dir_put_args;
  38 struct xfs_inode;
  39 struct xfs_mount;
  40 struct xfs_trans;
  41
  42 /*========================================================================
  43  * Directory Structure when equal to XFS_LBSIZE(mp) bytes.
  44  *========================================================================*/
  45
  46 /*
  47  * This is the structure of the leaf nodes in the Btree.
  48  *
  49  * Struct leaf_entry's are packed from the top.  Names grow from the bottom
  50  * but are not packed.  The freemap contains run-length-encoded entries
  51  * for the free bytes after the leaf_entry's, but only the N largest such,
  52  * smaller runs are dropped.  When the freemap doesn't show enough space
  53  * for an allocation, we compact the namelist area and try again.  If we
  54  * still don't have enough space, then we have to split the block.
  55  *
  56  * Since we have duplicate hash keys, for each key that matches, compare
  57  * the actual string.  The root and intermediate node search always takes
  58  * the first-in-the-block key match found, so we should only have to work
  59  * "forw"ard.  If none matches, continue with the "forw"ard leaf nodes
  60  * until the hash key changes or the filename is found.
  61  *
  62  * The parent directory and the self-pointer are explicitly represented
  63  * (ie: there are entries for "." and "..").
  64  *
  65  * Note that the count being a __uint16_t limits us to something like a
  66  * blocksize of 1.3MB in the face of worst case (short) filenames.
  67  */
  68 #define XFS_DIR_LEAF_MAPSIZE    3       /* how many freespace slots */
  69
  70 typedef struct xfs_dir_leaf_map {       /* RLE map of free bytes */
  71         __uint16_t      base;           /* base of free region */
  72         __uint16_t      size;           /* run length of free region */
  73 } xfs_dir_leaf_map_t;
  74
  75 typedef struct xfs_dir_leaf_hdr {       /* constant-structure header block */
  76         xfs_da_blkinfo_t info;          /* block type, links, etc. */
  77         __uint16_t      count;          /* count of active leaf_entry's */
  78         __uint16_t      namebytes;      /* num bytes of name strings stored */
  79         __uint16_t      firstused;      /* first used byte in name area */
  80         __uint8_t       holes;          /* != 0 if blk needs compaction */
  81         __uint8_t       pad1;
  82         xfs_dir_leaf_map_t freemap[XFS_DIR_LEAF_MAPSIZE];
  83 } xfs_dir_leaf_hdr_t;
  84
  85 typedef struct xfs_dir_leaf_entry {     /* sorted on key, not name */
  86         xfs_dahash_t    hashval;        /* hash value of name */
  87         __uint16_t      nameidx;        /* index into buffer of name */
  88         __uint8_t       namelen;        /* length of name string */
  89         __uint8_t       pad2;
  90 } xfs_dir_leaf_entry_t;
  91
  92 typedef struct xfs_dir_leaf_name {
  93         xfs_dir_ino_t   inumber;        /* inode number for this key */
  94         __uint8_t       name[1];        /* name string itself */
  95 } xfs_dir_leaf_name_t;
  96
  97 typedef struct xfs_dir_leafblock {
  98         xfs_dir_leaf_hdr_t      hdr;    /* constant-structure header block */
  99         xfs_dir_leaf_entry_t    entries[1];     /* var sized array */
 100         xfs_dir_leaf_name_t     namelist[1];    /* grows from bottom of buf */
 101 } xfs_dir_leafblock_t;
 102
 103 /*
 104  * Length of name for which a 512-byte block filesystem
 105  * can get a double split.
 106  */
 107 #define XFS_DIR_LEAF_CAN_DOUBLE_SPLIT_LEN       \
 108         (512 - (uint)sizeof(xfs_dir_leaf_hdr_t) - \
 109          (uint)sizeof(xfs_dir_leaf_entry_t) * 2 - \
 110          (uint)sizeof(xfs_dir_leaf_name_t) * 2 - (MAXNAMELEN - 2) + 1 + 1)
 111
 112 typedef int (*xfs_dir_put_t)(struct xfs_dir_put_args *pa);
 113
 114 typedef union {
 115         xfs_off_t               o;              /* offset (cookie) */
 116         /*
 117          * Watch the order here (endian-ness dependent).
 118          */
 119         struct {
 120 #ifndef XFS_NATIVE_HOST
 121                 xfs_dahash_t    h;      /* hash value */
 122                 __uint32_t      be;     /* block and entry */
 123 #else
 124                 __uint32_t      be;     /* block and entry */
 125                 xfs_dahash_t    h;      /* hash value */
 126 #endif /* XFS_NATIVE_HOST */
 127         } s;
 128 } xfs_dircook_t;
 129
 130 #define XFS_PUT_COOKIE(c,mp,bno,entry,hash)     \
 131         ((c).s.be = XFS_DA_MAKE_BNOENTRY(mp, bno, entry), (c).s.h = (hash))
 132
 133 typedef struct xfs_dir_put_args {
 134         xfs_dircook_t   cook;           /* cookie of (next) entry */
 135         xfs_intino_t    ino;            /* inode number */
 136         struct xfs_dirent *dbp;         /* buffer pointer */
 137         char            *name;          /* directory entry name */
 138         int             namelen;        /* length of name */
 139         int             done;           /* output: set if value was stored */
 140         xfs_dir_put_t   put;            /* put function ptr (i/o) */
 141         struct uio      *uio;           /* uio control structure */
 142 } xfs_dir_put_args_t;
 143
 144 #define XFS_DIR_LEAF_ENTSIZE_BYNAME(len)        \
 145         xfs_dir_leaf_entsize_byname(len)
 146 static inline int xfs_dir_leaf_entsize_byname(int len)
 147 {
 148         return (uint)sizeof(xfs_dir_leaf_name_t)-1 + len;
 149 }
 150
 151 #define XFS_DIR_LEAF_ENTSIZE_BYENTRY(entry)     \
 152         xfs_dir_leaf_entsize_byentry(entry)
 153 static inline int xfs_dir_leaf_entsize_byentry(xfs_dir_leaf_entry_t *entry)
 154 {
 155         return (uint)sizeof(xfs_dir_leaf_name_t)-1 + (entry)->namelen;
 156 }
 157
 158 #define XFS_DIR_LEAF_NAMESTRUCT(leafp,offset)   \
 159         xfs_dir_leaf_namestruct(leafp,offset)
 160 static inline xfs_dir_leaf_name_t *
 161 xfs_dir_leaf_namestruct(xfs_dir_leafblock_t *leafp, int offset)
 162 {
 163         return (xfs_dir_leaf_name_t *)&((char *)(leafp))[offset];
 164 }
 165
 166 /*========================================================================
 167  * Function prototypes for the kernel.
 168  *========================================================================*/
 169
 170 /*
 171  * Internal routines when dirsize < XFS_LITINO(mp).
 172  */
 173 int xfs_dir_shortform_create(struct xfs_da_args *args, xfs_ino_t parent);
 174 int xfs_dir_shortform_addname(struct xfs_da_args *args);
 175 int xfs_dir_shortform_lookup(struct xfs_da_args *args);
 176 int xfs_dir_shortform_to_leaf(struct xfs_da_args *args);
 177 int xfs_dir_shortform_removename(struct xfs_da_args *args);
 178 int xfs_dir_shortform_getdents(struct xfs_inode *dp, struct uio *uio, int *eofp,
 179                                struct xfs_dirent *dbp, xfs_dir_put_t put);
 180 int xfs_dir_shortform_replace(struct xfs_da_args *args);
 181
 182 /*
 183  * Internal routines when dirsize == XFS_LBSIZE(mp).
 184  */
 185 int xfs_dir_leaf_to_node(struct xfs_da_args *args);
 186 int xfs_dir_leaf_to_shortform(struct xfs_da_args *args);
 187
 188 /*
 189  * Routines used for growing the Btree.
 190  */
 191 int     xfs_dir_leaf_split(struct xfs_da_state *state,
 192                                   struct xfs_da_state_blk *oldblk,
 193                                   struct xfs_da_state_blk *newblk);
 194 int     xfs_dir_leaf_add(struct xfs_dabuf *leaf_buffer,
 195                                 struct xfs_da_args *args, int insertion_index);
 196 int     xfs_dir_leaf_addname(struct xfs_da_args *args);
 197 int     xfs_dir_leaf_lookup_int(struct xfs_dabuf *leaf_buffer,
 198                                        struct xfs_da_args *args,
 199                                        int *index_found_at);
 200 int     xfs_dir_leaf_remove(struct xfs_trans *trans,
 201                                    struct xfs_dabuf *leaf_buffer,
 202                                    int index_to_remove);
 203 int     xfs_dir_leaf_getdents_int(struct xfs_dabuf *bp, struct xfs_inode *dp,
 204                                          xfs_dablk_t bno, struct uio *uio,
 205                                          int *eobp, struct xfs_dirent *dbp,
 206                                          xfs_dir_put_t put, xfs_daddr_t nextda);
 207
 208 /*
 209  * Routines used for shrinking the Btree.
 210  */
 211 int     xfs_dir_leaf_toosmall(struct xfs_da_state *state, int *retval);
 212 void    xfs_dir_leaf_unbalance(struct xfs_da_state *state,
 213                                              struct xfs_da_state_blk *drop_blk,
 214                                              struct xfs_da_state_blk *save_blk);
 215
 216 /*
 217  * Utility routines.
 218  */
 219 uint    xfs_dir_leaf_lasthash(struct xfs_dabuf *bp, int *count);
 220 int     xfs_dir_leaf_order(struct xfs_dabuf *leaf1_bp,
 221                                   struct xfs_dabuf *leaf2_bp);
 222 int     xfs_dir_put_dirent64_direct(xfs_dir_put_args_t *pa);
 223 int     xfs_dir_put_dirent64_uio(xfs_dir_put_args_t *pa);
 224 int     xfs_dir_ino_validate(struct xfs_mount *mp, xfs_ino_t ino);
 225
 226 /*
 227  * Global data.
 228  */
 229 extern xfs_dahash_t     xfs_dir_hash_dot, xfs_dir_hash_dotdot;
 230
 231 #endif /* __XFS_DIR_LEAF_H__ */