fs/xfs/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 uio;
  46 struct xfs_bmap_free;
  47 struct xfs_dabuf;
  48 struct xfs_da_args;
  49 struct xfs_da_state;
  50 struct xfs_da_state_blk;
  51 struct xfs_dir_put_args;
  52 struct xfs_inode;
  53 struct xfs_mount;
  54 struct xfs_trans;
  55
  56 /*========================================================================
  57  * Directory Structure when equal to XFS_LBSIZE(mp) bytes.
  58  *========================================================================*/
  59
  60 /*
  61  * This is the structure of the leaf nodes in the Btree.
  62  *
  63  * Struct leaf_entry's are packed from the top.  Names grow from the bottom
  64  * but are not packed.  The freemap contains run-length-encoded entries
  65  * for the free bytes after the leaf_entry's, but only the N largest such,
  66  * smaller runs are dropped.  When the freemap doesn't show enough space
  67  * for an allocation, we compact the namelist area and try again.  If we
  68  * still don't have enough space, then we have to split the block.
  69  *
  70  * Since we have duplicate hash keys, for each key that matches, compare
  71  * the actual string.  The root and intermediate node search always takes
  72  * the first-in-the-block key match found, so we should only have to work
  73  * "forw"ard.  If none matches, continue with the "forw"ard leaf nodes
  74  * until the hash key changes or the filename is found.
  75  *
  76  * The parent directory and the self-pointer are explicitly represented
  77  * (ie: there are entries for "." and "..").
  78  *
  79  * Note that the count being a __uint16_t limits us to something like a
  80  * blocksize of 1.3MB in the face of worst case (short) filenames.
  81  */
  82 #define XFS_DIR_LEAF_MAPSIZE    3       /* how many freespace slots */
  83
  84 typedef struct xfs_dir_leafblock {
  85         struct xfs_dir_leaf_hdr {       /* constant-structure header block */
  86                 xfs_da_blkinfo_t info;  /* block type, links, etc. */
  87                 __uint16_t count;       /* count of active leaf_entry's */
  88                 __uint16_t namebytes;   /* num bytes of name strings stored */
  89                 __uint16_t firstused;   /* first used byte in name area */
  90                 __uint8_t  holes;       /* != 0 if blk needs compaction */
  91                 __uint8_t  pad1;
  92                 struct xfs_dir_leaf_map {/* RLE map of free bytes */
  93                         __uint16_t base; /* base of free region */
  94                         __uint16_t size; /* run length of free region */
  95                 } freemap[XFS_DIR_LEAF_MAPSIZE]; /* N largest free regions */
  96         } hdr;
  97         struct xfs_dir_leaf_entry {     /* sorted on key, not name */
  98                 xfs_dahash_t hashval;   /* hash value of name */
  99                 __uint16_t nameidx;     /* index into buffer of name */
 100                 __uint8_t namelen;      /* length of name string */
 101                 __uint8_t pad2;
 102         } entries[1];                   /* var sized array */
 103         struct xfs_dir_leaf_name {
 104                 xfs_dir_ino_t inumber;  /* inode number for this key */
 105                 __uint8_t name[1];      /* name string itself */
 106         } namelist[1];                  /* grows from bottom of buf */
 107 } xfs_dir_leafblock_t;
 108 typedef struct xfs_dir_leaf_hdr xfs_dir_leaf_hdr_t;
 109 typedef struct xfs_dir_leaf_map xfs_dir_leaf_map_t;
 110 typedef struct xfs_dir_leaf_entry xfs_dir_leaf_entry_t;
 111 typedef struct xfs_dir_leaf_name xfs_dir_leaf_name_t;
 112
 113 /*
 114  * Length of name for which a 512-byte block filesystem
 115  * can get a double split.
 116  */
 117 #define XFS_DIR_LEAF_CAN_DOUBLE_SPLIT_LEN       \
 118         (512 - (uint)sizeof(xfs_dir_leaf_hdr_t) - \
 119          (uint)sizeof(xfs_dir_leaf_entry_t) * 2 - \
 120          (uint)sizeof(xfs_dir_leaf_name_t) * 2 - (MAXNAMELEN - 2) + 1 + 1)
 121
 122 typedef int (*xfs_dir_put_t)(struct xfs_dir_put_args *pa);
 123
 124 typedef union {
 125         xfs_off_t               o;              /* offset (cookie) */
 126         /*
 127          * Watch the order here (endian-ness dependent).
 128          */
 129         struct {
 130 #if __BYTE_ORDER == __LITTLE_ENDIAN
 131                 xfs_dahash_t    h;      /* hash value */
 132                 __uint32_t      be;     /* block and entry */
 133 #else   /* __BYTE_ORDER == __BIG_ENDIAN */
 134                 __uint32_t      be;     /* block and entry */
 135                 xfs_dahash_t    h;      /* hash value */
 136 #endif  /* __BYTE_ORDER == __BIG_ENDIAN */
 137         } s;
 138 } xfs_dircook_t;
 139
 140 #define XFS_PUT_COOKIE(c,mp,bno,entry,hash)     \
 141         ((c).s.be = XFS_DA_MAKE_BNOENTRY(mp, bno, entry), (c).s.h = (hash))
 142
 143 typedef struct xfs_dir_put_args
 144 {
 145         xfs_dircook_t   cook;           /* cookie of (next) entry */
 146         xfs_intino_t    ino;            /* inode number */
 147         struct xfs_dirent       *dbp;           /* buffer pointer */
 148         char            *name;          /* directory entry name */
 149         int             namelen;        /* length of name */
 150         int             done;           /* output: set if value was stored */
 151         xfs_dir_put_t   put;            /* put function ptr (i/o) */
 152         struct uio      *uio;           /* uio control structure */
 153 } xfs_dir_put_args_t;
 154
 155 #if XFS_WANT_FUNCS || (XFS_WANT_SPACE && XFSSO_XFS_DIR_LEAF_ENTSIZE_BYNAME)
 156 int xfs_dir_leaf_entsize_byname(int len);
 157 #define XFS_DIR_LEAF_ENTSIZE_BYNAME(len)        xfs_dir_leaf_entsize_byname(len)
 158 #else
 159 #define XFS_DIR_LEAF_ENTSIZE_BYNAME(len)        /* space a name will use */ \
 160         ((uint)sizeof(xfs_dir_leaf_name_t)-1 + len)
 161 #endif
 162 #if XFS_WANT_FUNCS || (XFS_WANT_SPACE && XFSSO_XFS_DIR_LEAF_ENTSIZE_BYENTRY)
 163 int xfs_dir_leaf_entsize_byentry(xfs_dir_leaf_entry_t *entry);
 164 #define XFS_DIR_LEAF_ENTSIZE_BYENTRY(entry)     \
 165         xfs_dir_leaf_entsize_byentry(entry)
 166 #else
 167 #define XFS_DIR_LEAF_ENTSIZE_BYENTRY(entry)     /* space an entry will use */ \
 168         ((uint)sizeof(xfs_dir_leaf_name_t)-1 + (entry)->namelen)
 169 #endif
 170 #if XFS_WANT_FUNCS || (XFS_WANT_SPACE && XFSSO_XFS_DIR_LEAF_NAMESTRUCT)
 171 xfs_dir_leaf_name_t *
 172 xfs_dir_leaf_namestruct(xfs_dir_leafblock_t *leafp, int offset);
 173 #define XFS_DIR_LEAF_NAMESTRUCT(leafp,offset)   \
 174         xfs_dir_leaf_namestruct(leafp,offset)
 175 #else
 176 #define XFS_DIR_LEAF_NAMESTRUCT(leafp,offset)   /* point to name struct */ \
 177         ((xfs_dir_leaf_name_t *)&((char *)(leafp))[offset])
 178 #endif
 179
 180 /*========================================================================
 181  * Function prototypes for the kernel.
 182  *========================================================================*/
 183
 184 /*
 185  * Internal routines when dirsize < XFS_LITINO(mp).
 186  */
 187 int xfs_dir_shortform_create(struct xfs_da_args *args, xfs_ino_t parent);
 188 int xfs_dir_shortform_addname(struct xfs_da_args *args);
 189 int xfs_dir_shortform_lookup(struct xfs_da_args *args);
 190 int xfs_dir_shortform_to_leaf(struct xfs_da_args *args);
 191 int xfs_dir_shortform_removename(struct xfs_da_args *args);
 192 int xfs_dir_shortform_getdents(struct xfs_inode *dp, struct uio *uio, int *eofp,
 193                                       struct xfs_dirent *dbp, xfs_dir_put_t put);
 194 int xfs_dir_shortform_replace(struct xfs_da_args *args);
 195
 196 /*
 197  * Internal routines when dirsize == XFS_LBSIZE(mp).
 198  */
 199 int xfs_dir_leaf_to_node(struct xfs_da_args *args);
 200 int xfs_dir_leaf_to_shortform(struct xfs_da_args *args);
 201
 202 /*
 203  * Routines used for growing the Btree.
 204  */
 205 int     xfs_dir_leaf_split(struct xfs_da_state *state,
 206                                   struct xfs_da_state_blk *oldblk,
 207                                   struct xfs_da_state_blk *newblk);
 208 int     xfs_dir_leaf_add(struct xfs_dabuf *leaf_buffer,
 209                                 struct xfs_da_args *args, int insertion_index);
 210 int     xfs_dir_leaf_addname(struct xfs_da_args *args);
 211 int     xfs_dir_leaf_lookup_int(struct xfs_dabuf *leaf_buffer,
 212                                        struct xfs_da_args *args,
 213                                        int *index_found_at);
 214 int     xfs_dir_leaf_remove(struct xfs_trans *trans,
 215                                    struct xfs_dabuf *leaf_buffer,
 216                                    int index_to_remove);
 217 int     xfs_dir_leaf_getdents_int(struct xfs_dabuf *bp, struct xfs_inode *dp,
 218                                          xfs_dablk_t bno, struct uio *uio,
 219                                          int *eobp, struct xfs_dirent *dbp,
 220                                          xfs_dir_put_t put, xfs_daddr_t nextda);
 221
 222 /*
 223  * Routines used for shrinking the Btree.
 224  */
 225 int     xfs_dir_leaf_toosmall(struct xfs_da_state *state, int *retval);
 226 void    xfs_dir_leaf_unbalance(struct xfs_da_state *state,
 227                                              struct xfs_da_state_blk *drop_blk,
 228                                              struct xfs_da_state_blk *save_blk);
 229
 230 /*
 231  * Utility routines.
 232  */
 233 uint    xfs_dir_leaf_lasthash(struct xfs_dabuf *bp, int *count);
 234 int     xfs_dir_leaf_order(struct xfs_dabuf *leaf1_bp,
 235                                   struct xfs_dabuf *leaf2_bp);
 236 int     xfs_dir_put_dirent64_direct(xfs_dir_put_args_t *pa);
 237 int     xfs_dir_put_dirent64_uio(xfs_dir_put_args_t *pa);
 238 int     xfs_dir_ino_validate(struct xfs_mount *mp, xfs_ino_t ino);
 239
 240
 241 /*
 242  * Global data.
 243  */
 244 extern xfs_dahash_t     xfs_dir_hash_dot, xfs_dir_hash_dotdot;
 245
 246 #endif /* __XFS_DIR_LEAF_H__ */