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_leafblock {
  71         struct xfs_dir_leaf_hdr {       /* constant-structure header block */
  72                 xfs_da_blkinfo_t info;  /* block type, links, etc. */
  73                 __uint16_t count;       /* count of active leaf_entry's */
  74                 __uint16_t namebytes;   /* num bytes of name strings stored */
  75                 __uint16_t firstused;   /* first used byte in name area */
  76                 __uint8_t  holes;       /* != 0 if blk needs compaction */
  77                 __uint8_t  pad1;
  78                 struct xfs_dir_leaf_map {/* RLE map of free bytes */
  79                         __uint16_t base; /* base of free region */
  80                         __uint16_t size; /* run length of free region */
  81                 } freemap[XFS_DIR_LEAF_MAPSIZE]; /* N largest free regions */
  82         } hdr;
  83         struct xfs_dir_leaf_entry {     /* sorted on key, not name */
  84                 xfs_dahash_t hashval;   /* hash value of name */
  85                 __uint16_t nameidx;     /* index into buffer of name */
  86                 __uint8_t namelen;      /* length of name string */
  87                 __uint8_t pad2;
  88         } entries[1];                   /* var sized array */
  89         struct xfs_dir_leaf_name {
  90                 xfs_dir_ino_t inumber;  /* inode number for this key */
  91                 __uint8_t name[1];      /* name string itself */
  92         } namelist[1];                  /* grows from bottom of buf */
  93 } xfs_dir_leafblock_t;
  94 typedef struct xfs_dir_leaf_hdr xfs_dir_leaf_hdr_t;
  95 typedef struct xfs_dir_leaf_map xfs_dir_leaf_map_t;
  96 typedef struct xfs_dir_leaf_entry xfs_dir_leaf_entry_t;
  97 typedef struct xfs_dir_leaf_name xfs_dir_leaf_name_t;
  98
  99 /*
 100  * Length of name for which a 512-byte block filesystem
 101  * can get a double split.
 102  */
 103 #define XFS_DIR_LEAF_CAN_DOUBLE_SPLIT_LEN       \
 104         (512 - (uint)sizeof(xfs_dir_leaf_hdr_t) - \
 105          (uint)sizeof(xfs_dir_leaf_entry_t) * 2 - \
 106          (uint)sizeof(xfs_dir_leaf_name_t) * 2 - (MAXNAMELEN - 2) + 1 + 1)
 107
 108 typedef int (*xfs_dir_put_t)(struct xfs_dir_put_args *pa);
 109
 110 typedef union {
 111         xfs_off_t               o;              /* offset (cookie) */
 112         /*
 113          * Watch the order here (endian-ness dependent).
 114          */
 115         struct {
 116 #ifndef XFS_NATIVE_HOST
 117                 xfs_dahash_t    h;      /* hash value */
 118                 __uint32_t      be;     /* block and entry */
 119 #else
 120                 __uint32_t      be;     /* block and entry */
 121                 xfs_dahash_t    h;      /* hash value */
 122 #endif /* XFS_NATIVE_HOST */
 123         } s;
 124 } xfs_dircook_t;
 125
 126 #define XFS_PUT_COOKIE(c,mp,bno,entry,hash)     \
 127         ((c).s.be = XFS_DA_MAKE_BNOENTRY(mp, bno, entry), (c).s.h = (hash))
 128
 129 typedef struct xfs_dir_put_args
 130 {
 131         xfs_dircook_t   cook;           /* cookie of (next) entry */
 132         xfs_intino_t    ino;            /* inode number */
 133         struct xfs_dirent       *dbp;           /* buffer pointer */
 134         char            *name;          /* directory entry name */
 135         int             namelen;        /* length of name */
 136         int             done;           /* output: set if value was stored */
 137         xfs_dir_put_t   put;            /* put function ptr (i/o) */
 138         struct uio      *uio;           /* uio control structure */
 139 } xfs_dir_put_args_t;
 140
 141 #define XFS_DIR_LEAF_ENTSIZE_BYNAME(len)        xfs_dir_leaf_entsize_byname(len)
 142 static inline int xfs_dir_leaf_entsize_byname(int len)
 143 {
 144         return (uint)sizeof(xfs_dir_leaf_name_t)-1 + len;
 145 }
 146
 147 #define XFS_DIR_LEAF_ENTSIZE_BYENTRY(entry)     \
 148         xfs_dir_leaf_entsize_byentry(entry)
 149 static inline int xfs_dir_leaf_entsize_byentry(xfs_dir_leaf_entry_t *entry)
 150 {
 151         return (uint)sizeof(xfs_dir_leaf_name_t)-1 + (entry)->namelen;
 152 }
 153
 154 #define XFS_DIR_LEAF_NAMESTRUCT(leafp,offset)   \
 155         xfs_dir_leaf_namestruct(leafp,offset)
 156 static inline xfs_dir_leaf_name_t *
 157 xfs_dir_leaf_namestruct(xfs_dir_leafblock_t *leafp, int offset)
 158 {
 159         return (xfs_dir_leaf_name_t *)&((char *)(leafp))[offset];
 160 }
 161
 162 /*========================================================================
 163  * Function prototypes for the kernel.
 164  *========================================================================*/
 165
 166 /*
 167  * Internal routines when dirsize < XFS_LITINO(mp).
 168  */
 169 int xfs_dir_shortform_create(struct xfs_da_args *args, xfs_ino_t parent);
 170 int xfs_dir_shortform_addname(struct xfs_da_args *args);
 171 int xfs_dir_shortform_lookup(struct xfs_da_args *args);
 172 int xfs_dir_shortform_to_leaf(struct xfs_da_args *args);
 173 int xfs_dir_shortform_removename(struct xfs_da_args *args);
 174 int xfs_dir_shortform_getdents(struct xfs_inode *dp, struct uio *uio, int *eofp,
 175                                struct xfs_dirent *dbp, xfs_dir_put_t put);
 176 int xfs_dir_shortform_replace(struct xfs_da_args *args);
 177
 178 /*
 179  * Internal routines when dirsize == XFS_LBSIZE(mp).
 180  */
 181 int xfs_dir_leaf_to_node(struct xfs_da_args *args);
 182 int xfs_dir_leaf_to_shortform(struct xfs_da_args *args);
 183
 184 /*
 185  * Routines used for growing the Btree.
 186  */
 187 int     xfs_dir_leaf_split(struct xfs_da_state *state,
 188                                   struct xfs_da_state_blk *oldblk,
 189                                   struct xfs_da_state_blk *newblk);
 190 int     xfs_dir_leaf_add(struct xfs_dabuf *leaf_buffer,
 191                                 struct xfs_da_args *args, int insertion_index);
 192 int     xfs_dir_leaf_addname(struct xfs_da_args *args);
 193 int     xfs_dir_leaf_lookup_int(struct xfs_dabuf *leaf_buffer,
 194                                        struct xfs_da_args *args,
 195                                        int *index_found_at);
 196 int     xfs_dir_leaf_remove(struct xfs_trans *trans,
 197                                    struct xfs_dabuf *leaf_buffer,
 198                                    int index_to_remove);
 199 int     xfs_dir_leaf_getdents_int(struct xfs_dabuf *bp, struct xfs_inode *dp,
 200                                          xfs_dablk_t bno, struct uio *uio,
 201                                          int *eobp, struct xfs_dirent *dbp,
 202                                          xfs_dir_put_t put, xfs_daddr_t nextda);
 203
 204 /*
 205  * Routines used for shrinking the Btree.
 206  */
 207 int     xfs_dir_leaf_toosmall(struct xfs_da_state *state, int *retval);
 208 void    xfs_dir_leaf_unbalance(struct xfs_da_state *state,
 209                                              struct xfs_da_state_blk *drop_blk,
 210                                              struct xfs_da_state_blk *save_blk);
 211
 212 /*
 213  * Utility routines.
 214  */
 215 uint    xfs_dir_leaf_lasthash(struct xfs_dabuf *bp, int *count);
 216 int     xfs_dir_leaf_order(struct xfs_dabuf *leaf1_bp,
 217                                   struct xfs_dabuf *leaf2_bp);
 218 int     xfs_dir_put_dirent64_direct(xfs_dir_put_args_t *pa);
 219 int     xfs_dir_put_dirent64_uio(xfs_dir_put_args_t *pa);
 220 int     xfs_dir_ino_validate(struct xfs_mount *mp, xfs_ino_t ino);
 221
 222 /*
 223  * Global data.
 224  */
 225 extern xfs_dahash_t     xfs_dir_hash_dot, xfs_dir_hash_dotdot;
 226
 227 #endif /* __XFS_DIR_LEAF_H__ */