linux/fs/xfs/xfs_attr_leaf.h
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   1/*
   2 * Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
   3 * Copyright (c) 2013 Red Hat, Inc.
   4 * All Rights Reserved.
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License as
   8 * published by the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it would be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 * GNU General Public License for more details.
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * along with this program; if not, write the Free Software Foundation,
  17 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18 */
  19#ifndef __XFS_ATTR_LEAF_H__
  20#define __XFS_ATTR_LEAF_H__
  21
  22/*
  23 * Attribute storage layout, internal structure, access macros, etc.
  24 *
  25 * Attribute lists are structured around Btrees where all the data
  26 * elements are in the leaf nodes.  Attribute names are hashed into an int,
  27 * then that int is used as the index into the Btree.  Since the hashval
  28 * of an attribute name may not be unique, we may have duplicate keys.  The
  29 * internal links in the Btree are logical block offsets into the file.
  30 */
  31
  32struct attrlist;
  33struct attrlist_cursor_kern;
  34struct xfs_attr_list_context;
  35struct xfs_da_args;
  36struct xfs_da_state;
  37struct xfs_da_state_blk;
  38struct xfs_inode;
  39struct xfs_trans;
  40
  41/*========================================================================
  42 * Attribute structure when equal to XFS_LBSIZE(mp) bytes.
  43 *========================================================================*/
  44
  45/*
  46 * This is the structure of the leaf nodes in the Btree.
  47 *
  48 * Struct leaf_entry's are packed from the top.  Name/values grow from the
  49 * bottom but are not packed.  The freemap contains run-length-encoded entries
  50 * for the free bytes after the leaf_entry's, but only the N largest such,
  51 * smaller runs are dropped.  When the freemap doesn't show enough space
  52 * for an allocation, we compact the name/value area and try again.  If we
  53 * still don't have enough space, then we have to split the block.  The
  54 * name/value structs (both local and remote versions) must be 32bit aligned.
  55 *
  56 * Since we have duplicate hash keys, for each key that matches, compare
  57 * the actual name string.  The root and intermediate node search always
  58 * takes the first-in-the-block key match found, so we should only have
  59 * to work "forw"ard.  If none matches, continue with the "forw"ard leaf
  60 * nodes until the hash key changes or the attribute name is found.
  61 *
  62 * We store the fact that an attribute is a ROOT/USER/SECURE attribute in
  63 * the leaf_entry.  The namespaces are independent only because we also look
  64 * at the namespace bit when we are looking for a matching attribute name.
  65 *
  66 * We also store an "incomplete" bit in the leaf_entry.  It shows that an
  67 * attribute is in the middle of being created and should not be shown to
  68 * the user if we crash during the time that the bit is set.  We clear the
  69 * bit when we have finished setting up the attribute.  We do this because
  70 * we cannot create some large attributes inside a single transaction, and we
  71 * need some indication that we weren't finished if we crash in the middle.
  72 */
  73#define XFS_ATTR_LEAF_MAPSIZE   3       /* how many freespace slots */
  74
  75typedef struct xfs_attr_leaf_map {      /* RLE map of free bytes */
  76        __be16  base;                     /* base of free region */
  77        __be16  size;                     /* length of free region */
  78} xfs_attr_leaf_map_t;
  79
  80typedef struct xfs_attr_leaf_hdr {      /* constant-structure header block */
  81        xfs_da_blkinfo_t info;          /* block type, links, etc. */
  82        __be16  count;                  /* count of active leaf_entry's */
  83        __be16  usedbytes;              /* num bytes of names/values stored */
  84        __be16  firstused;              /* first used byte in name area */
  85        __u8    holes;                  /* != 0 if blk needs compaction */
  86        __u8    pad1;
  87        xfs_attr_leaf_map_t freemap[XFS_ATTR_LEAF_MAPSIZE];
  88                                        /* N largest free regions */
  89} xfs_attr_leaf_hdr_t;
  90
  91typedef struct xfs_attr_leaf_entry {    /* sorted on key, not name */
  92        __be32  hashval;                /* hash value of name */
  93        __be16  nameidx;                /* index into buffer of name/value */
  94        __u8    flags;                  /* LOCAL/ROOT/SECURE/INCOMPLETE flag */
  95        __u8    pad2;                   /* unused pad byte */
  96} xfs_attr_leaf_entry_t;
  97
  98typedef struct xfs_attr_leaf_name_local {
  99        __be16  valuelen;               /* number of bytes in value */
 100        __u8    namelen;                /* length of name bytes */
 101        __u8    nameval[1];             /* name/value bytes */
 102} xfs_attr_leaf_name_local_t;
 103
 104typedef struct xfs_attr_leaf_name_remote {
 105        __be32  valueblk;               /* block number of value bytes */
 106        __be32  valuelen;               /* number of bytes in value */
 107        __u8    namelen;                /* length of name bytes */
 108        __u8    name[1];                /* name bytes */
 109} xfs_attr_leaf_name_remote_t;
 110
 111typedef struct xfs_attr_leafblock {
 112        xfs_attr_leaf_hdr_t     hdr;    /* constant-structure header block */
 113        xfs_attr_leaf_entry_t   entries[1];     /* sorted on key, not name */
 114        xfs_attr_leaf_name_local_t namelist;    /* grows from bottom of buf */
 115        xfs_attr_leaf_name_remote_t valuelist;  /* grows from bottom of buf */
 116} xfs_attr_leafblock_t;
 117
 118/*
 119 * CRC enabled leaf structures. Called "version 3" structures to match the
 120 * version number of the directory and dablk structures for this feature, and
 121 * attr2 is already taken by the variable inode attribute fork size feature.
 122 */
 123struct xfs_attr3_leaf_hdr {
 124        struct xfs_da3_blkinfo  info;
 125        __be16                  count;
 126        __be16                  usedbytes;
 127        __be16                  firstused;
 128        __u8                    holes;
 129        __u8                    pad1;
 130        struct xfs_attr_leaf_map freemap[XFS_ATTR_LEAF_MAPSIZE];
 131        __be32                  pad2;           /* 64 bit alignment */
 132};
 133
 134#define XFS_ATTR3_LEAF_CRC_OFF  (offsetof(struct xfs_attr3_leaf_hdr, info.crc))
 135
 136struct xfs_attr3_leafblock {
 137        struct xfs_attr3_leaf_hdr       hdr;
 138        struct xfs_attr_leaf_entry      entries[1];
 139
 140        /*
 141         * The rest of the block contains the following structures after the
 142         * leaf entries, growing from the bottom up. The variables are never
 143         * referenced, the locations accessed purely from helper functions.
 144         *
 145         * struct xfs_attr_leaf_name_local
 146         * struct xfs_attr_leaf_name_remote
 147         */
 148};
 149
 150/*
 151 * incore, neutral version of the attribute leaf header
 152 */
 153struct xfs_attr3_icleaf_hdr {
 154        __uint32_t      forw;
 155        __uint32_t      back;
 156        __uint16_t      magic;
 157        __uint16_t      count;
 158        __uint16_t      usedbytes;
 159        __uint16_t      firstused;
 160        __u8            holes;
 161        struct {
 162                __uint16_t      base;
 163                __uint16_t      size;
 164        } freemap[XFS_ATTR_LEAF_MAPSIZE];
 165};
 166
 167/*
 168 * Flags used in the leaf_entry[i].flags field.
 169 * NOTE: the INCOMPLETE bit must not collide with the flags bits specified
 170 * on the system call, they are "or"ed together for various operations.
 171 */
 172#define XFS_ATTR_LOCAL_BIT      0       /* attr is stored locally */
 173#define XFS_ATTR_ROOT_BIT       1       /* limit access to trusted attrs */
 174#define XFS_ATTR_SECURE_BIT     2       /* limit access to secure attrs */
 175#define XFS_ATTR_INCOMPLETE_BIT 7       /* attr in middle of create/delete */
 176#define XFS_ATTR_LOCAL          (1 << XFS_ATTR_LOCAL_BIT)
 177#define XFS_ATTR_ROOT           (1 << XFS_ATTR_ROOT_BIT)
 178#define XFS_ATTR_SECURE         (1 << XFS_ATTR_SECURE_BIT)
 179#define XFS_ATTR_INCOMPLETE     (1 << XFS_ATTR_INCOMPLETE_BIT)
 180
 181/*
 182 * Conversion macros for converting namespace bits from argument flags
 183 * to ondisk flags.
 184 */
 185#define XFS_ATTR_NSP_ARGS_MASK          (ATTR_ROOT | ATTR_SECURE)
 186#define XFS_ATTR_NSP_ONDISK_MASK        (XFS_ATTR_ROOT | XFS_ATTR_SECURE)
 187#define XFS_ATTR_NSP_ONDISK(flags)      ((flags) & XFS_ATTR_NSP_ONDISK_MASK)
 188#define XFS_ATTR_NSP_ARGS(flags)        ((flags) & XFS_ATTR_NSP_ARGS_MASK)
 189#define XFS_ATTR_NSP_ARGS_TO_ONDISK(x)  (((x) & ATTR_ROOT ? XFS_ATTR_ROOT : 0) |\
 190                                         ((x) & ATTR_SECURE ? XFS_ATTR_SECURE : 0))
 191#define XFS_ATTR_NSP_ONDISK_TO_ARGS(x)  (((x) & XFS_ATTR_ROOT ? ATTR_ROOT : 0) |\
 192                                         ((x) & XFS_ATTR_SECURE ? ATTR_SECURE : 0))
 193
 194/*
 195 * Alignment for namelist and valuelist entries (since they are mixed
 196 * there can be only one alignment value)
 197 */
 198#define XFS_ATTR_LEAF_NAME_ALIGN        ((uint)sizeof(xfs_dablk_t))
 199
 200static inline int
 201xfs_attr3_leaf_hdr_size(struct xfs_attr_leafblock *leafp)
 202{
 203        if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC))
 204                return sizeof(struct xfs_attr3_leaf_hdr);
 205        return sizeof(struct xfs_attr_leaf_hdr);
 206}
 207
 208static inline struct xfs_attr_leaf_entry *
 209xfs_attr3_leaf_entryp(xfs_attr_leafblock_t *leafp)
 210{
 211        if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC))
 212                return &((struct xfs_attr3_leafblock *)leafp)->entries[0];
 213        return &leafp->entries[0];
 214}
 215
 216/*
 217 * Cast typed pointers for "local" and "remote" name/value structs.
 218 */
 219static inline char *
 220xfs_attr3_leaf_name(xfs_attr_leafblock_t *leafp, int idx)
 221{
 222        struct xfs_attr_leaf_entry *entries = xfs_attr3_leaf_entryp(leafp);
 223
 224        return &((char *)leafp)[be16_to_cpu(entries[idx].nameidx)];
 225}
 226
 227static inline xfs_attr_leaf_name_remote_t *
 228xfs_attr3_leaf_name_remote(xfs_attr_leafblock_t *leafp, int idx)
 229{
 230        return (xfs_attr_leaf_name_remote_t *)xfs_attr3_leaf_name(leafp, idx);
 231}
 232
 233static inline xfs_attr_leaf_name_local_t *
 234xfs_attr3_leaf_name_local(xfs_attr_leafblock_t *leafp, int idx)
 235{
 236        return (xfs_attr_leaf_name_local_t *)xfs_attr3_leaf_name(leafp, idx);
 237}
 238
 239/*
 240 * Calculate total bytes used (including trailing pad for alignment) for
 241 * a "local" name/value structure, a "remote" name/value structure, and
 242 * a pointer which might be either.
 243 */
 244static inline int xfs_attr_leaf_entsize_remote(int nlen)
 245{
 246        return ((uint)sizeof(xfs_attr_leaf_name_remote_t) - 1 + (nlen) + \
 247                XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 248}
 249
 250static inline int xfs_attr_leaf_entsize_local(int nlen, int vlen)
 251{
 252        return ((uint)sizeof(xfs_attr_leaf_name_local_t) - 1 + (nlen) + (vlen) +
 253                XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 254}
 255
 256static inline int xfs_attr_leaf_entsize_local_max(int bsize)
 257{
 258        return (((bsize) >> 1) + ((bsize) >> 2));
 259}
 260
 261/*
 262 * Used to keep a list of "remote value" extents when unlinking an inode.
 263 */
 264typedef struct xfs_attr_inactive_list {
 265        xfs_dablk_t     valueblk;       /* block number of value bytes */
 266        int             valuelen;       /* number of bytes in value */
 267} xfs_attr_inactive_list_t;
 268
 269
 270/*========================================================================
 271 * Function prototypes for the kernel.
 272 *========================================================================*/
 273
 274/*
 275 * Internal routines when attribute fork size < XFS_LITINO(mp).
 276 */
 277void    xfs_attr_shortform_create(struct xfs_da_args *args);
 278void    xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff);
 279int     xfs_attr_shortform_lookup(struct xfs_da_args *args);
 280int     xfs_attr_shortform_getvalue(struct xfs_da_args *args);
 281int     xfs_attr_shortform_to_leaf(struct xfs_da_args *args);
 282int     xfs_attr_shortform_remove(struct xfs_da_args *args);
 283int     xfs_attr_shortform_list(struct xfs_attr_list_context *context);
 284int     xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp);
 285int     xfs_attr_shortform_bytesfit(xfs_inode_t *dp, int bytes);
 286
 287
 288/*
 289 * Internal routines when attribute fork size == XFS_LBSIZE(mp).
 290 */
 291int     xfs_attr3_leaf_to_node(struct xfs_da_args *args);
 292int     xfs_attr3_leaf_to_shortform(struct xfs_buf *bp,
 293                                   struct xfs_da_args *args, int forkoff);
 294int     xfs_attr3_leaf_clearflag(struct xfs_da_args *args);
 295int     xfs_attr3_leaf_setflag(struct xfs_da_args *args);
 296int     xfs_attr3_leaf_flipflags(struct xfs_da_args *args);
 297
 298/*
 299 * Routines used for growing the Btree.
 300 */
 301int     xfs_attr3_leaf_split(struct xfs_da_state *state,
 302                                   struct xfs_da_state_blk *oldblk,
 303                                   struct xfs_da_state_blk *newblk);
 304int     xfs_attr3_leaf_lookup_int(struct xfs_buf *leaf,
 305                                        struct xfs_da_args *args);
 306int     xfs_attr3_leaf_getvalue(struct xfs_buf *bp, struct xfs_da_args *args);
 307int     xfs_attr3_leaf_add(struct xfs_buf *leaf_buffer,
 308                                 struct xfs_da_args *args);
 309int     xfs_attr3_leaf_remove(struct xfs_buf *leaf_buffer,
 310                                    struct xfs_da_args *args);
 311int     xfs_attr3_leaf_list_int(struct xfs_buf *bp,
 312                                      struct xfs_attr_list_context *context);
 313
 314/*
 315 * Routines used for shrinking the Btree.
 316 */
 317int     xfs_attr3_leaf_toosmall(struct xfs_da_state *state, int *retval);
 318void    xfs_attr3_leaf_unbalance(struct xfs_da_state *state,
 319                                       struct xfs_da_state_blk *drop_blk,
 320                                       struct xfs_da_state_blk *save_blk);
 321int     xfs_attr3_root_inactive(struct xfs_trans **trans, struct xfs_inode *dp);
 322
 323/*
 324 * Utility routines.
 325 */
 326xfs_dahash_t    xfs_attr_leaf_lasthash(struct xfs_buf *bp, int *count);
 327int     xfs_attr_leaf_order(struct xfs_buf *leaf1_bp,
 328                                   struct xfs_buf *leaf2_bp);
 329int     xfs_attr_leaf_newentsize(int namelen, int valuelen, int blocksize,
 330                                        int *local);
 331int     xfs_attr3_leaf_read(struct xfs_trans *tp, struct xfs_inode *dp,
 332                        xfs_dablk_t bno, xfs_daddr_t mappedbno,
 333                        struct xfs_buf **bpp);
 334void    xfs_attr3_leaf_hdr_from_disk(struct xfs_attr3_icleaf_hdr *to,
 335                                     struct xfs_attr_leafblock *from);
 336
 337extern const struct xfs_buf_ops xfs_attr3_leaf_buf_ops;
 338
 339#endif  /* __XFS_ATTR_LEAF_H__ */
 340
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