include/xfs_dir_leaf.h

   1 /*
   2  * Copyright (c) 2000-2001 Silicon Graphics, Inc.  All Rights Reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it would be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  11  *
  12  * Further, this software is distributed without any warranty that it is
  13  * free of the rightful claim of any third person regarding infringement
  14  * or the like.  Any license provided herein, whether implied or
  15  * otherwise, applies only to this software file.  Patent licenses, if
  16  * any, provided herein do not apply to combinations of this program with
  17  * other software, or any other product whatsoever.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write the Free Software Foundation, Inc., 59
  21  * Temple Place - Suite 330, Boston MA 02111-1307, USA.
  22  *
  23  * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
  24  * Mountain View, CA  94043, or:
  25  *
  26  * http://www.sgi.com
  27  *
  28  * For further information regarding this notice, see:
  29  *
  30  * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
  31  */
  32 #ifndef __XFS_DIR_LEAF_H__
  33 #define __XFS_DIR_LEAF_H__
  34
  35 /*
  36  * Directory layout, internal structure, access macros, etc.
  37  *
  38  * Large directories are structured around Btrees where all the data
  39  * elements are in the leaf nodes.  Filenames are hashed into an int,
  40  * then that int is used as the index into the Btree.  Since the hashval
  41  * of a filename may not be unique, we may have duplicate keys.  The
  42  * internal links in the Btree are logical block offsets into the file.
  43  */
  44
  45 struct dirent;
  46 struct uio;
  47 struct xfs_bmap_free;
  48 struct xfs_dabuf;
  49 struct xfs_da_args;
  50 struct xfs_da_state;
  51 struct xfs_da_state_blk;
  52 struct xfs_dir_put_args;
  53 struct xfs_inode;
  54 struct xfs_mount;
  55 struct xfs_trans;
  56
  57 /*========================================================================
  58  * Directory Structure when equal to XFS_LBSIZE(mp) bytes.
  59  *========================================================================*/
  60
  61 /*
  62  * This is the structure of the leaf nodes in the Btree.
  63  *
  64  * Struct leaf_entry's are packed from the top.  Names grow from the bottom
  65  * but are not packed.  The freemap contains run-length-encoded entries
  66  * for the free bytes after the leaf_entry's, but only the N largest such,
  67  * smaller runs are dropped.  When the freemap doesn't show enough space
  68  * for an allocation, we compact the namelist area and try again.  If we
  69  * still don't have enough space, then we have to split the block.
  70  *
  71  * Since we have duplicate hash keys, for each key that matches, compare
  72  * the actual string.  The root and intermediate node search always takes
  73  * the first-in-the-block key match found, so we should only have to work
  74  * "forw"ard.  If none matches, continue with the "forw"ard leaf nodes
  75  * until the hash key changes or the filename is found.
  76  *
  77  * The parent directory and the self-pointer are explicitly represented
  78  * (ie: there are entries for "." and "..").
  79  *
  80  * Note that the count being a __uint16_t limits us to something like a
  81  * blocksize of 1.3MB in the face of worst case (short) filenames.
  82  */
  83 #define XFS_DIR_LEAF_MAPSIZE    3       /* how many freespace slots */
  84
  85 typedef struct xfs_dir_leafblock {
  86         struct xfs_dir_leaf_hdr {       /* constant-structure header block */
  87                 xfs_da_blkinfo_t info;  /* block type, links, etc. */
  88                 __uint16_t count;       /* count of active leaf_entry's */
  89                 __uint16_t namebytes;   /* num bytes of name strings stored */
  90                 __uint16_t firstused;   /* first used byte in name area */
  91                 __uint8_t  holes;       /* != 0 if blk needs compaction */
  92                 __uint8_t  pad1;
  93                 struct xfs_dir_leaf_map {/* RLE map of free bytes */
  94                         __uint16_t base; /* base of free region */
  95                         __uint16_t size; /* run length of free region */
  96                 } freemap[XFS_DIR_LEAF_MAPSIZE]; /* N largest free regions */
  97         } hdr;
  98         struct xfs_dir_leaf_entry {     /* sorted on key, not name */
  99                 xfs_dahash_t hashval;   /* hash value of name */
 100                 __uint16_t nameidx;     /* index into buffer of name */
 101                 __uint8_t namelen;      /* length of name string */
 102                 __uint8_t pad2;
 103         } entries[1];                   /* var sized array */
 104         struct xfs_dir_leaf_name {
 105                 xfs_dir_ino_t inumber;  /* inode number for this key */
 106                 __uint8_t name[1];      /* name string itself */
 107         } namelist[1];                  /* grows from bottom of buf */
 108 } xfs_dir_leafblock_t;
 109 typedef struct xfs_dir_leaf_hdr xfs_dir_leaf_hdr_t;
 110 typedef struct xfs_dir_leaf_map xfs_dir_leaf_map_t;
 111 typedef struct xfs_dir_leaf_entry xfs_dir_leaf_entry_t;
 112 typedef struct xfs_dir_leaf_name xfs_dir_leaf_name_t;
 113
 114 /*
 115  * Length of name for which a 512-byte block filesystem
 116  * can get a double split.
 117  */
 118 #define XFS_DIR_LEAF_CAN_DOUBLE_SPLIT_LEN       \
 119         (512 - (uint)sizeof(xfs_dir_leaf_hdr_t) - \
 120          (uint)sizeof(xfs_dir_leaf_entry_t) * 2 - \
 121          (uint)sizeof(xfs_dir_leaf_name_t) * 2 - (MAXNAMELEN - 2) + 1 + 1)
 122
 123 typedef int (*xfs_dir_put_t)(struct xfs_dir_put_args *pa);
 124
 125 typedef union {
 126         xfs_off_t               o;              /* offset (cookie) */
 127         /*
 128          * Watch the order here (endian-ness dependent).
 129          */
 130         struct {
 131 #if __BYTE_ORDER == __LITTLE_ENDIAN
 132                 xfs_dahash_t    h;      /* hash value */
 133                 __uint32_t      be;     /* block and entry */
 134 #else   /* __BYTE_ORDER == __BIG_ENDIAN */
 135                 __uint32_t      be;     /* block and entry */
 136                 xfs_dahash_t    h;      /* hash value */
 137 #endif  /* __BYTE_ORDER == __BIG_ENDIAN */
 138         } s;
 139 } xfs_dircook_t;
 140
 141 #define XFS_PUT_COOKIE(c,mp,bno,entry,hash)     \
 142         ((c).s.be = XFS_DA_MAKE_BNOENTRY(mp, bno, entry), (c).s.h = (hash))
 143
 144 #define XFS_GET_DIR_INO_ARCH(mp,di,arch) \
 145     DIRINO_GET_ARCH(&(di),arch)
 146 #define XFS_GET_DIR_INO(mp,di) \
 147     XFS_GET_DIR_INO_ARCH(mp,di,ARCH_NOCONVERT)
 148
 149 typedef struct xfs_dir_put_args
 150 {
 151         xfs_dircook_t   cook;           /* cookie of (next) entry */
 152         xfs_intino_t    ino;            /* inode number */
 153         struct xfs_dirent       *dbp;           /* buffer pointer */
 154         char            *name;          /* directory entry name */
 155         int             namelen;        /* length of name */
 156         int             done;           /* output: set if value was stored */
 157         xfs_dir_put_t   put;            /* put function ptr (i/o) */
 158         struct uio      *uio;           /* uio control structure */
 159 } xfs_dir_put_args_t;
 160
 161 #if XFS_WANT_FUNCS || (XFS_WANT_SPACE && XFSSO_XFS_DIR_LEAF_ENTSIZE_BYNAME)
 162 int xfs_dir_leaf_entsize_byname(int len);
 163 #define XFS_DIR_LEAF_ENTSIZE_BYNAME(len)        xfs_dir_leaf_entsize_byname(len)
 164 #else
 165 #define XFS_DIR_LEAF_ENTSIZE_BYNAME(len)        /* space a name will use */ \
 166         ((uint)sizeof(xfs_dir_leaf_name_t)-1 + len)
 167 #endif
 168 #if XFS_WANT_FUNCS || (XFS_WANT_SPACE && XFSSO_XFS_DIR_LEAF_ENTSIZE_BYENTRY)
 169 int xfs_dir_leaf_entsize_byentry(xfs_dir_leaf_entry_t *entry);
 170 #define XFS_DIR_LEAF_ENTSIZE_BYENTRY(entry)     \
 171         xfs_dir_leaf_entsize_byentry(entry)
 172 #else
 173 #define XFS_DIR_LEAF_ENTSIZE_BYENTRY(entry)     /* space an entry will use */ \
 174         ((uint)sizeof(xfs_dir_leaf_name_t)-1 + (entry)->namelen)
 175 #endif
 176 #if XFS_WANT_FUNCS || (XFS_WANT_SPACE && XFSSO_XFS_DIR_LEAF_NAMESTRUCT)
 177 xfs_dir_leaf_name_t *
 178 xfs_dir_leaf_namestruct(xfs_dir_leafblock_t *leafp, int offset);
 179 #define XFS_DIR_LEAF_NAMESTRUCT(leafp,offset)   \
 180         xfs_dir_leaf_namestruct(leafp,offset)
 181 #else
 182 #define XFS_DIR_LEAF_NAMESTRUCT(leafp,offset)   /* point to name struct */ \
 183         ((xfs_dir_leaf_name_t *)&((char *)(leafp))[offset])
 184 #endif
 185
 186 /*========================================================================
 187  * Function prototypes for the kernel.
 188  *========================================================================*/
 189
 190 /*
 191  * Internal routines when dirsize < XFS_LITINO(mp).
 192  */
 193 int xfs_dir_shortform_create(struct xfs_da_args *args, xfs_ino_t parent);
 194 int xfs_dir_shortform_addname(struct xfs_da_args *args);
 195 int xfs_dir_shortform_lookup(struct xfs_da_args *args);
 196 int xfs_dir_shortform_to_leaf(struct xfs_da_args *args);
 197 int xfs_dir_shortform_removename(struct xfs_da_args *args);
 198 int xfs_dir_shortform_getdents(struct xfs_inode *dp, struct uio *uio, int *eofp,
 199                                       struct xfs_dirent *dbp, xfs_dir_put_t put);
 200 int xfs_dir_shortform_replace(struct xfs_da_args *args);
 201
 202 /*
 203  * Internal routines when dirsize == XFS_LBSIZE(mp).
 204  */
 205 int xfs_dir_leaf_to_node(struct xfs_da_args *args);
 206 int xfs_dir_leaf_to_shortform(struct xfs_da_args *args);
 207
 208 /*
 209  * Routines used for growing the Btree.
 210  */
 211 int     xfs_dir_leaf_create(struct xfs_da_args *args, xfs_dablk_t which_block,
 212                                    struct xfs_dabuf **bpp);
 213 int     xfs_dir_leaf_split(struct xfs_da_state *state,
 214                                   struct xfs_da_state_blk *oldblk,
 215                                   struct xfs_da_state_blk *newblk);
 216 int     xfs_dir_leaf_add(struct xfs_dabuf *leaf_buffer,
 217                                 struct xfs_da_args *args, int insertion_index);
 218 int     xfs_dir_leaf_addname(struct xfs_da_args *args);
 219 int     xfs_dir_leaf_lookup_int(struct xfs_dabuf *leaf_buffer,
 220                                        struct xfs_da_args *args,
 221                                        int *index_found_at);
 222 int     xfs_dir_leaf_remove(struct xfs_trans *trans,
 223                                    struct xfs_dabuf *leaf_buffer,
 224                                    int index_to_remove);
 225 int     xfs_dir_leaf_getdents_int(struct xfs_dabuf *bp, struct xfs_inode *dp,
 226                                          xfs_dablk_t bno, struct uio *uio,
 227                                          int *eobp, struct xfs_dirent *dbp,
 228                                          xfs_dir_put_t put, xfs_daddr_t nextda);
 229
 230 /*
 231  * Routines used for shrinking the Btree.
 232  */
 233 int     xfs_dir_leaf_toosmall(struct xfs_da_state *state, int *retval);
 234 void    xfs_dir_leaf_unbalance(struct xfs_da_state *state,
 235                                              struct xfs_da_state_blk *drop_blk,
 236                                              struct xfs_da_state_blk *save_blk);
 237
 238 /*
 239  * Utility routines.
 240  */
 241 uint    xfs_dir_leaf_lasthash(struct xfs_dabuf *bp, int *count);
 242 int     xfs_dir_leaf_order(struct xfs_dabuf *leaf1_bp,
 243                                   struct xfs_dabuf *leaf2_bp);
 244 int     xfs_dir_put_dirent32_direct(xfs_dir_put_args_t *pa);
 245 int     xfs_dir_put_dirent32_uio(xfs_dir_put_args_t *pa);
 246 int     xfs_dir_put_dirent64_direct(xfs_dir_put_args_t *pa);
 247 int     xfs_dir_put_dirent64_uio(xfs_dir_put_args_t *pa);
 248 int     xfs_dir_ino_validate(struct xfs_mount *mp, xfs_ino_t ino);
 249
 250
 251 /*
 252  * Global data.
 253  */
 254 extern xfs_dahash_t     xfs_dir_hash_dot, xfs_dir_hash_dotdot;
 255
 256 #endif /* __XFS_DIR_LEAF_H__ */