linux/fs/xfs/xfs_attr_leaf.h
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   1/*
   2 * Copyright (c) 2000,2002-2003,2005 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_ATTR_LEAF_H__
  19#define __XFS_ATTR_LEAF_H__
  20
  21/*
  22 * Attribute storage layout, internal structure, access macros, etc.
  23 *
  24 * Attribute lists are structured around Btrees where all the data
  25 * elements are in the leaf nodes.  Attribute names are hashed into an int,
  26 * then that int is used as the index into the Btree.  Since the hashval
  27 * of an attribute name 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
  31struct attrlist;
  32struct attrlist_cursor_kern;
  33struct xfs_attr_list_context;
  34struct xfs_da_args;
  35struct xfs_da_state;
  36struct xfs_da_state_blk;
  37struct xfs_inode;
  38struct xfs_trans;
  39
  40/*========================================================================
  41 * Attribute structure when equal to XFS_LBSIZE(mp) bytes.
  42 *========================================================================*/
  43
  44/*
  45 * This is the structure of the leaf nodes in the Btree.
  46 *
  47 * Struct leaf_entry's are packed from the top.  Name/values grow from the
  48 * bottom but are not packed.  The freemap contains run-length-encoded entries
  49 * for the free bytes after the leaf_entry's, but only the N largest such,
  50 * smaller runs are dropped.  When the freemap doesn't show enough space
  51 * for an allocation, we compact the name/value area and try again.  If we
  52 * still don't have enough space, then we have to split the block.  The
  53 * name/value structs (both local and remote versions) must be 32bit aligned.
  54 *
  55 * Since we have duplicate hash keys, for each key that matches, compare
  56 * the actual name string.  The root and intermediate node search always
  57 * takes the first-in-the-block key match found, so we should only have
  58 * to work "forw"ard.  If none matches, continue with the "forw"ard leaf
  59 * nodes until the hash key changes or the attribute name is found.
  60 *
  61 * We store the fact that an attribute is a ROOT/USER/SECURE attribute in
  62 * the leaf_entry.  The namespaces are independent only because we also look
  63 * at the namespace bit when we are looking for a matching attribute name.
  64 *
  65 * We also store an "incomplete" bit in the leaf_entry.  It shows that an
  66 * attribute is in the middle of being created and should not be shown to
  67 * the user if we crash during the time that the bit is set.  We clear the
  68 * bit when we have finished setting up the attribute.  We do this because
  69 * we cannot create some large attributes inside a single transaction, and we
  70 * need some indication that we weren't finished if we crash in the middle.
  71 */
  72#define XFS_ATTR_LEAF_MAPSIZE   3       /* how many freespace slots */
  73
  74typedef struct xfs_attr_leaf_map {      /* RLE map of free bytes */
  75        __be16  base;                     /* base of free region */
  76        __be16  size;                     /* length of free region */
  77} xfs_attr_leaf_map_t;
  78
  79typedef struct xfs_attr_leaf_hdr {      /* constant-structure header block */
  80        xfs_da_blkinfo_t info;          /* block type, links, etc. */
  81        __be16  count;                  /* count of active leaf_entry's */
  82        __be16  usedbytes;              /* num bytes of names/values stored */
  83        __be16  firstused;              /* first used byte in name area */
  84        __u8    holes;                  /* != 0 if blk needs compaction */
  85        __u8    pad1;
  86        xfs_attr_leaf_map_t freemap[XFS_ATTR_LEAF_MAPSIZE];
  87                                        /* N largest free regions */
  88} xfs_attr_leaf_hdr_t;
  89
  90typedef struct xfs_attr_leaf_entry {    /* sorted on key, not name */
  91        __be32  hashval;                /* hash value of name */
  92        __be16  nameidx;                /* index into buffer of name/value */
  93        __u8    flags;                  /* LOCAL/ROOT/SECURE/INCOMPLETE flag */
  94        __u8    pad2;                   /* unused pad byte */
  95} xfs_attr_leaf_entry_t;
  96
  97typedef struct xfs_attr_leaf_name_local {
  98        __be16  valuelen;               /* number of bytes in value */
  99        __u8    namelen;                /* length of name bytes */
 100        __u8    nameval[1];             /* name/value bytes */
 101} xfs_attr_leaf_name_local_t;
 102
 103typedef struct xfs_attr_leaf_name_remote {
 104        __be32  valueblk;               /* block number of value bytes */
 105        __be32  valuelen;               /* number of bytes in value */
 106        __u8    namelen;                /* length of name bytes */
 107        __u8    name[1];                /* name bytes */
 108} xfs_attr_leaf_name_remote_t;
 109
 110typedef struct xfs_attr_leafblock {
 111        xfs_attr_leaf_hdr_t     hdr;    /* constant-structure header block */
 112        xfs_attr_leaf_entry_t   entries[1];     /* sorted on key, not name */
 113        xfs_attr_leaf_name_local_t namelist;    /* grows from bottom of buf */
 114        xfs_attr_leaf_name_remote_t valuelist;  /* grows from bottom of buf */
 115} xfs_attr_leafblock_t;
 116
 117/*
 118 * Flags used in the leaf_entry[i].flags field.
 119 * NOTE: the INCOMPLETE bit must not collide with the flags bits specified
 120 * on the system call, they are "or"ed together for various operations.
 121 */
 122#define XFS_ATTR_LOCAL_BIT      0       /* attr is stored locally */
 123#define XFS_ATTR_ROOT_BIT       1       /* limit access to trusted attrs */
 124#define XFS_ATTR_SECURE_BIT     2       /* limit access to secure attrs */
 125#define XFS_ATTR_INCOMPLETE_BIT 7       /* attr in middle of create/delete */
 126#define XFS_ATTR_LOCAL          (1 << XFS_ATTR_LOCAL_BIT)
 127#define XFS_ATTR_ROOT           (1 << XFS_ATTR_ROOT_BIT)
 128#define XFS_ATTR_SECURE         (1 << XFS_ATTR_SECURE_BIT)
 129#define XFS_ATTR_INCOMPLETE     (1 << XFS_ATTR_INCOMPLETE_BIT)
 130
 131/*
 132 * Conversion macros for converting namespace bits from argument flags
 133 * to ondisk flags.
 134 */
 135#define XFS_ATTR_NSP_ARGS_MASK          (ATTR_ROOT | ATTR_SECURE)
 136#define XFS_ATTR_NSP_ONDISK_MASK        (XFS_ATTR_ROOT | XFS_ATTR_SECURE)
 137#define XFS_ATTR_NSP_ONDISK(flags)      ((flags) & XFS_ATTR_NSP_ONDISK_MASK)
 138#define XFS_ATTR_NSP_ARGS(flags)        ((flags) & XFS_ATTR_NSP_ARGS_MASK)
 139#define XFS_ATTR_NSP_ARGS_TO_ONDISK(x)  (((x) & ATTR_ROOT ? XFS_ATTR_ROOT : 0) |\
 140                                         ((x) & ATTR_SECURE ? XFS_ATTR_SECURE : 0))
 141#define XFS_ATTR_NSP_ONDISK_TO_ARGS(x)  (((x) & XFS_ATTR_ROOT ? ATTR_ROOT : 0) |\
 142                                         ((x) & XFS_ATTR_SECURE ? ATTR_SECURE : 0))
 143
 144/*
 145 * Alignment for namelist and valuelist entries (since they are mixed
 146 * there can be only one alignment value)
 147 */
 148#define XFS_ATTR_LEAF_NAME_ALIGN        ((uint)sizeof(xfs_dablk_t))
 149
 150/*
 151 * Cast typed pointers for "local" and "remote" name/value structs.
 152 */
 153static inline xfs_attr_leaf_name_remote_t *
 154xfs_attr_leaf_name_remote(xfs_attr_leafblock_t *leafp, int idx)
 155{
 156        return (xfs_attr_leaf_name_remote_t *)
 157                &((char *)leafp)[be16_to_cpu(leafp->entries[idx].nameidx)];
 158}
 159
 160static inline xfs_attr_leaf_name_local_t *
 161xfs_attr_leaf_name_local(xfs_attr_leafblock_t *leafp, int idx)
 162{
 163        return (xfs_attr_leaf_name_local_t *)
 164                &((char *)leafp)[be16_to_cpu(leafp->entries[idx].nameidx)];
 165}
 166
 167static inline char *xfs_attr_leaf_name(xfs_attr_leafblock_t *leafp, int idx)
 168{
 169        return &((char *)leafp)[be16_to_cpu(leafp->entries[idx].nameidx)];
 170}
 171
 172/*
 173 * Calculate total bytes used (including trailing pad for alignment) for
 174 * a "local" name/value structure, a "remote" name/value structure, and
 175 * a pointer which might be either.
 176 */
 177static inline int xfs_attr_leaf_entsize_remote(int nlen)
 178{
 179        return ((uint)sizeof(xfs_attr_leaf_name_remote_t) - 1 + (nlen) + \
 180                XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 181}
 182
 183static inline int xfs_attr_leaf_entsize_local(int nlen, int vlen)
 184{
 185        return ((uint)sizeof(xfs_attr_leaf_name_local_t) - 1 + (nlen) + (vlen) +
 186                XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 187}
 188
 189static inline int xfs_attr_leaf_entsize_local_max(int bsize)
 190{
 191        return (((bsize) >> 1) + ((bsize) >> 2));
 192}
 193
 194/*
 195 * Used to keep a list of "remote value" extents when unlinking an inode.
 196 */
 197typedef struct xfs_attr_inactive_list {
 198        xfs_dablk_t     valueblk;       /* block number of value bytes */
 199        int             valuelen;       /* number of bytes in value */
 200} xfs_attr_inactive_list_t;
 201
 202
 203/*========================================================================
 204 * Function prototypes for the kernel.
 205 *========================================================================*/
 206
 207/*
 208 * Internal routines when attribute fork size < XFS_LITINO(mp).
 209 */
 210void    xfs_attr_shortform_create(struct xfs_da_args *args);
 211void    xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff);
 212int     xfs_attr_shortform_lookup(struct xfs_da_args *args);
 213int     xfs_attr_shortform_getvalue(struct xfs_da_args *args);
 214int     xfs_attr_shortform_to_leaf(struct xfs_da_args *args);
 215int     xfs_attr_shortform_remove(struct xfs_da_args *args);
 216int     xfs_attr_shortform_list(struct xfs_attr_list_context *context);
 217int     xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp);
 218int     xfs_attr_shortform_bytesfit(xfs_inode_t *dp, int bytes);
 219
 220
 221/*
 222 * Internal routines when attribute fork size == XFS_LBSIZE(mp).
 223 */
 224int     xfs_attr_leaf_to_node(struct xfs_da_args *args);
 225int     xfs_attr_leaf_to_shortform(struct xfs_buf *bp,
 226                                   struct xfs_da_args *args, int forkoff);
 227int     xfs_attr_leaf_clearflag(struct xfs_da_args *args);
 228int     xfs_attr_leaf_setflag(struct xfs_da_args *args);
 229int     xfs_attr_leaf_flipflags(xfs_da_args_t *args);
 230
 231/*
 232 * Routines used for growing the Btree.
 233 */
 234int     xfs_attr_leaf_split(struct xfs_da_state *state,
 235                                   struct xfs_da_state_blk *oldblk,
 236                                   struct xfs_da_state_blk *newblk);
 237int     xfs_attr_leaf_lookup_int(struct xfs_buf *leaf,
 238                                        struct xfs_da_args *args);
 239int     xfs_attr_leaf_getvalue(struct xfs_buf *bp, struct xfs_da_args *args);
 240int     xfs_attr_leaf_add(struct xfs_buf *leaf_buffer,
 241                                 struct xfs_da_args *args);
 242int     xfs_attr_leaf_remove(struct xfs_buf *leaf_buffer,
 243                                    struct xfs_da_args *args);
 244int     xfs_attr_leaf_list_int(struct xfs_buf *bp,
 245                                      struct xfs_attr_list_context *context);
 246
 247/*
 248 * Routines used for shrinking the Btree.
 249 */
 250int     xfs_attr_leaf_toosmall(struct xfs_da_state *state, int *retval);
 251void    xfs_attr_leaf_unbalance(struct xfs_da_state *state,
 252                                       struct xfs_da_state_blk *drop_blk,
 253                                       struct xfs_da_state_blk *save_blk);
 254int     xfs_attr_root_inactive(struct xfs_trans **trans, struct xfs_inode *dp);
 255
 256/*
 257 * Utility routines.
 258 */
 259xfs_dahash_t    xfs_attr_leaf_lasthash(struct xfs_buf *bp, int *count);
 260int     xfs_attr_leaf_order(struct xfs_buf *leaf1_bp,
 261                                   struct xfs_buf *leaf2_bp);
 262int     xfs_attr_leaf_newentsize(int namelen, int valuelen, int blocksize,
 263                                        int *local);
 264#endif  /* __XFS_ATTR_LEAF_H__ */
 265
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