fs/xfs/xfs_attr_leaf.h

   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
  31 struct attrlist;
  32 struct attrlist_cursor_kern;
  33 struct attrnames;
  34 struct xfs_dabuf;
  35 struct xfs_da_args;
  36 struct xfs_da_state;
  37 struct xfs_da_state_blk;
  38 struct xfs_inode;
  39 struct 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 a "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
  75 typedef struct xfs_attr_leafblock {
  76         struct xfs_attr_leaf_hdr {      /* constant-structure header block */
  77                 xfs_da_blkinfo_t info;  /* block type, links, etc. */
  78                 __uint16_t count;       /* count of active leaf_entry's */
  79                 __uint16_t usedbytes;   /* num bytes of names/values stored */
  80                 __uint16_t firstused;   /* first used byte in name area */
  81                 __uint8_t  holes;       /* != 0 if blk needs compaction */
  82                 __uint8_t  pad1;
  83                 struct xfs_attr_leaf_map {        /* RLE map of free bytes */
  84                         __uint16_t base;          /* base of free region */
  85                         __uint16_t size;          /* length of free region */
  86                 } freemap[XFS_ATTR_LEAF_MAPSIZE]; /* N largest free regions */
  87         } hdr;
  88         struct xfs_attr_leaf_entry {    /* sorted on key, not name */
  89                 xfs_dahash_t hashval;   /* hash value of name */
  90                 __uint16_t nameidx;     /* index into buffer of name/value */
  91                 __uint8_t flags;        /* LOCAL/ROOT/SECURE/INCOMPLETE flag */
  92                 __uint8_t pad2;         /* unused pad byte */
  93         } entries[1];                   /* variable sized array */
  94         struct xfs_attr_leaf_name_local {
  95                 __uint16_t valuelen;    /* number of bytes in value */
  96                 __uint8_t namelen;      /* length of name bytes */
  97                 __uint8_t nameval[1];   /* name/value bytes */
  98         } namelist;                     /* grows from bottom of buf */
  99         struct xfs_attr_leaf_name_remote {
 100                 xfs_dablk_t valueblk;   /* block number of value bytes */
 101                 __uint32_t valuelen;    /* number of bytes in value */
 102                 __uint8_t namelen;      /* length of name bytes */
 103                 __uint8_t name[1];      /* name bytes */
 104         } valuelist;                    /* grows from bottom of buf */
 105 } xfs_attr_leafblock_t;
 106 typedef struct xfs_attr_leaf_hdr xfs_attr_leaf_hdr_t;
 107 typedef struct xfs_attr_leaf_map xfs_attr_leaf_map_t;
 108 typedef struct xfs_attr_leaf_entry xfs_attr_leaf_entry_t;
 109 typedef struct xfs_attr_leaf_name_local xfs_attr_leaf_name_local_t;
 110 typedef struct xfs_attr_leaf_name_remote xfs_attr_leaf_name_remote_t;
 111
 112 /*
 113  * Flags used in the leaf_entry[i].flags field.
 114  * NOTE: the INCOMPLETE bit must not collide with the flags bits specified
 115  * on the system call, they are "or"ed together for various operations.
 116  */
 117 #define XFS_ATTR_LOCAL_BIT      0       /* attr is stored locally */
 118 #define XFS_ATTR_ROOT_BIT       1       /* limit access to trusted attrs */
 119 #define XFS_ATTR_SECURE_BIT     2       /* limit access to secure attrs */
 120 #define XFS_ATTR_INCOMPLETE_BIT 7       /* attr in middle of create/delete */
 121 #define XFS_ATTR_LOCAL          (1 << XFS_ATTR_LOCAL_BIT)
 122 #define XFS_ATTR_ROOT           (1 << XFS_ATTR_ROOT_BIT)
 123 #define XFS_ATTR_SECURE         (1 << XFS_ATTR_SECURE_BIT)
 124 #define XFS_ATTR_INCOMPLETE     (1 << XFS_ATTR_INCOMPLETE_BIT)
 125
 126 /*
 127  * Alignment for namelist and valuelist entries (since they are mixed
 128  * there can be only one alignment value)
 129  */
 130 #define XFS_ATTR_LEAF_NAME_ALIGN        ((uint)sizeof(xfs_dablk_t))
 131
 132 /*
 133  * Cast typed pointers for "local" and "remote" name/value structs.
 134  */
 135 #define XFS_ATTR_LEAF_NAME_REMOTE(leafp,idx)    \
 136         xfs_attr_leaf_name_remote(leafp,idx)
 137 static inline xfs_attr_leaf_name_remote_t *
 138 xfs_attr_leaf_name_remote(xfs_attr_leafblock_t *leafp, int idx)
 139 {
 140         return (xfs_attr_leaf_name_remote_t *) &((char *)
 141                 (leafp))[INT_GET((leafp)->entries[idx].nameidx, ARCH_CONVERT)];
 142 }
 143
 144 #define XFS_ATTR_LEAF_NAME_LOCAL(leafp,idx)     \
 145         xfs_attr_leaf_name_local(leafp,idx)
 146 static inline xfs_attr_leaf_name_local_t *
 147 xfs_attr_leaf_name_local(xfs_attr_leafblock_t *leafp, int idx)
 148 {
 149         return (xfs_attr_leaf_name_local_t *) &((char *)
 150                 (leafp))[INT_GET((leafp)->entries[idx].nameidx, ARCH_CONVERT)];
 151 }
 152
 153 #define XFS_ATTR_LEAF_NAME(leafp,idx)           xfs_attr_leaf_name(leafp,idx)
 154 static inline char *xfs_attr_leaf_name(xfs_attr_leafblock_t *leafp, int idx)
 155 {
 156         return (&((char *)
 157                 (leafp))[INT_GET((leafp)->entries[idx].nameidx, ARCH_CONVERT)]);
 158 }
 159
 160 /*
 161  * Calculate total bytes used (including trailing pad for alignment) for
 162  * a "local" name/value structure, a "remote" name/value structure, and
 163  * a pointer which might be either.
 164  */
 165 #define XFS_ATTR_LEAF_ENTSIZE_REMOTE(nlen)      \
 166         xfs_attr_leaf_entsize_remote(nlen)
 167 static inline int xfs_attr_leaf_entsize_remote(int nlen)
 168 {
 169         return ((uint)sizeof(xfs_attr_leaf_name_remote_t) - 1 + (nlen) + \
 170                 XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 171 }
 172
 173 #define XFS_ATTR_LEAF_ENTSIZE_LOCAL(nlen,vlen)  \
 174         xfs_attr_leaf_entsize_local(nlen,vlen)
 175 static inline int xfs_attr_leaf_entsize_local(int nlen, int vlen)
 176 {
 177         return ((uint)sizeof(xfs_attr_leaf_name_local_t) - 1 + (nlen) + (vlen) +
 178                 XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 179 }
 180
 181 #define XFS_ATTR_LEAF_ENTSIZE_LOCAL_MAX(bsize)  \
 182         xfs_attr_leaf_entsize_local_max(bsize)
 183 static inline int xfs_attr_leaf_entsize_local_max(int bsize)
 184 {
 185         return (((bsize) >> 1) + ((bsize) >> 2));
 186 }
 187
 188
 189 /*========================================================================
 190  * Structure used to pass context around among the routines.
 191  *========================================================================*/
 192
 193 typedef struct xfs_attr_list_context {
 194         struct xfs_inode                *dp;    /* inode */
 195         struct attrlist_cursor_kern     *cursor;/* position in list */
 196         struct attrlist                 *alist; /* output buffer */
 197         int                             count;  /* num used entries */
 198         int                             dupcnt; /* count dup hashvals seen */
 199         int                             bufsize;/* total buffer size */
 200         int                             firstu; /* first used byte in buffer */
 201         int                             flags;  /* from VOP call */
 202         int                             resynch;/* T/F: resynch with cursor */
 203 } xfs_attr_list_context_t;
 204
 205 /*
 206  * Used to keep a list of "remote value" extents when unlinking an inode.
 207  */
 208 typedef struct xfs_attr_inactive_list {
 209         xfs_dablk_t     valueblk;       /* block number of value bytes */
 210         int             valuelen;       /* number of bytes in value */
 211 } xfs_attr_inactive_list_t;
 212
 213
 214 /*========================================================================
 215  * Function prototypes for the kernel.
 216  *========================================================================*/
 217
 218 /*
 219  * Internal routines when attribute fork size < XFS_LITINO(mp).
 220  */
 221 void    xfs_attr_shortform_create(struct xfs_da_args *args);
 222 void    xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff);
 223 int     xfs_attr_shortform_lookup(struct xfs_da_args *args);
 224 int     xfs_attr_shortform_getvalue(struct xfs_da_args *args);
 225 int     xfs_attr_shortform_to_leaf(struct xfs_da_args *args);
 226 int     xfs_attr_shortform_remove(struct xfs_da_args *args);
 227 int     xfs_attr_shortform_list(struct xfs_attr_list_context *context);
 228 int     xfs_attr_shortform_allfit(struct xfs_dabuf *bp, struct xfs_inode *dp);
 229 int     xfs_attr_shortform_bytesfit(xfs_inode_t *dp, int bytes);
 230
 231
 232 /*
 233  * Internal routines when attribute fork size == XFS_LBSIZE(mp).
 234  */
 235 int     xfs_attr_leaf_to_node(struct xfs_da_args *args);
 236 int     xfs_attr_leaf_to_shortform(struct xfs_dabuf *bp,
 237                                    struct xfs_da_args *args, int forkoff);
 238 int     xfs_attr_leaf_clearflag(struct xfs_da_args *args);
 239 int     xfs_attr_leaf_setflag(struct xfs_da_args *args);
 240 int     xfs_attr_leaf_flipflags(xfs_da_args_t *args);
 241
 242 /*
 243  * Routines used for growing the Btree.
 244  */
 245 int     xfs_attr_leaf_split(struct xfs_da_state *state,
 246                                    struct xfs_da_state_blk *oldblk,
 247                                    struct xfs_da_state_blk *newblk);
 248 int     xfs_attr_leaf_lookup_int(struct xfs_dabuf *leaf,
 249                                         struct xfs_da_args *args);
 250 int     xfs_attr_leaf_getvalue(struct xfs_dabuf *bp, struct xfs_da_args *args);
 251 int     xfs_attr_leaf_add(struct xfs_dabuf *leaf_buffer,
 252                                  struct xfs_da_args *args);
 253 int     xfs_attr_leaf_remove(struct xfs_dabuf *leaf_buffer,
 254                                     struct xfs_da_args *args);
 255 int     xfs_attr_leaf_list_int(struct xfs_dabuf *bp,
 256                                       struct xfs_attr_list_context *context);
 257
 258 /*
 259  * Routines used for shrinking the Btree.
 260  */
 261 int     xfs_attr_leaf_toosmall(struct xfs_da_state *state, int *retval);
 262 void    xfs_attr_leaf_unbalance(struct xfs_da_state *state,
 263                                        struct xfs_da_state_blk *drop_blk,
 264                                        struct xfs_da_state_blk *save_blk);
 265 int     xfs_attr_root_inactive(struct xfs_trans **trans, struct xfs_inode *dp);
 266
 267 /*
 268  * Utility routines.
 269  */
 270 xfs_dahash_t    xfs_attr_leaf_lasthash(struct xfs_dabuf *bp, int *count);
 271 int     xfs_attr_leaf_order(struct xfs_dabuf *leaf1_bp,
 272                                    struct xfs_dabuf *leaf2_bp);
 273 int     xfs_attr_leaf_newentsize(int namelen, int valuelen, int blocksize,
 274                                         int *local);
 275 int     xfs_attr_rolltrans(struct xfs_trans **transp, struct xfs_inode *dp);
 276
 277 #endif  /* __XFS_ATTR_LEAF_H__ */