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 xfs_attr_list_context;
  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 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
  75 typedef 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
  80 typedef 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
  91 typedef 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
  98 typedef 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
 104 typedef 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
 111 typedef 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  * Flags used in the leaf_entry[i].flags field.
 120  * NOTE: the INCOMPLETE bit must not collide with the flags bits specified
 121  * on the system call, they are "or"ed together for various operations.
 122  */
 123 #define XFS_ATTR_LOCAL_BIT      0       /* attr is stored locally */
 124 #define XFS_ATTR_ROOT_BIT       1       /* limit access to trusted attrs */
 125 #define XFS_ATTR_SECURE_BIT     2       /* limit access to secure attrs */
 126 #define XFS_ATTR_INCOMPLETE_BIT 7       /* attr in middle of create/delete */
 127 #define XFS_ATTR_LOCAL          (1 << XFS_ATTR_LOCAL_BIT)
 128 #define XFS_ATTR_ROOT           (1 << XFS_ATTR_ROOT_BIT)
 129 #define XFS_ATTR_SECURE         (1 << XFS_ATTR_SECURE_BIT)
 130 #define XFS_ATTR_INCOMPLETE     (1 << XFS_ATTR_INCOMPLETE_BIT)
 131
 132 /*
 133  * Conversion macros for converting namespace bits from argument flags
 134  * to ondisk flags.
 135  */
 136 #define XFS_ATTR_NSP_ARGS_MASK          (ATTR_ROOT | ATTR_SECURE)
 137 #define XFS_ATTR_NSP_ONDISK_MASK        (XFS_ATTR_ROOT | XFS_ATTR_SECURE)
 138 #define XFS_ATTR_NSP_ONDISK(flags)      ((flags) & XFS_ATTR_NSP_ONDISK_MASK)
 139 #define XFS_ATTR_NSP_ARGS(flags)        ((flags) & XFS_ATTR_NSP_ARGS_MASK)
 140 #define XFS_ATTR_NSP_ARGS_TO_ONDISK(x)  (((x) & ATTR_ROOT ? XFS_ATTR_ROOT : 0) |\
 141                                          ((x) & ATTR_SECURE ? XFS_ATTR_SECURE : 0))
 142 #define XFS_ATTR_NSP_ONDISK_TO_ARGS(x)  (((x) & XFS_ATTR_ROOT ? ATTR_ROOT : 0) |\
 143                                          ((x) & XFS_ATTR_SECURE ? ATTR_SECURE : 0))
 144
 145 /*
 146  * Alignment for namelist and valuelist entries (since they are mixed
 147  * there can be only one alignment value)
 148  */
 149 #define XFS_ATTR_LEAF_NAME_ALIGN        ((uint)sizeof(xfs_dablk_t))
 150
 151 /*
 152  * Cast typed pointers for "local" and "remote" name/value structs.
 153  */
 154 static inline xfs_attr_leaf_name_remote_t *
 155 xfs_attr_leaf_name_remote(xfs_attr_leafblock_t *leafp, int idx)
 156 {
 157         return (xfs_attr_leaf_name_remote_t *)
 158                 &((char *)leafp)[be16_to_cpu(leafp->entries[idx].nameidx)];
 159 }
 160
 161 static inline xfs_attr_leaf_name_local_t *
 162 xfs_attr_leaf_name_local(xfs_attr_leafblock_t *leafp, int idx)
 163 {
 164         return (xfs_attr_leaf_name_local_t *)
 165                 &((char *)leafp)[be16_to_cpu(leafp->entries[idx].nameidx)];
 166 }
 167
 168 static inline char *xfs_attr_leaf_name(xfs_attr_leafblock_t *leafp, int idx)
 169 {
 170         return &((char *)leafp)[be16_to_cpu(leafp->entries[idx].nameidx)];
 171 }
 172
 173 /*
 174  * Calculate total bytes used (including trailing pad for alignment) for
 175  * a "local" name/value structure, a "remote" name/value structure, and
 176  * a pointer which might be either.
 177  */
 178 static inline int xfs_attr_leaf_entsize_remote(int nlen)
 179 {
 180         return ((uint)sizeof(xfs_attr_leaf_name_remote_t) - 1 + (nlen) + \
 181                 XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 182 }
 183
 184 static inline int xfs_attr_leaf_entsize_local(int nlen, int vlen)
 185 {
 186         return ((uint)sizeof(xfs_attr_leaf_name_local_t) - 1 + (nlen) + (vlen) +
 187                 XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
 188 }
 189
 190 static inline int xfs_attr_leaf_entsize_local_max(int bsize)
 191 {
 192         return (((bsize) >> 1) + ((bsize) >> 2));
 193 }
 194
 195 /*
 196  * Used to keep a list of "remote value" extents when unlinking an inode.
 197  */
 198 typedef struct xfs_attr_inactive_list {
 199         xfs_dablk_t     valueblk;       /* block number of value bytes */
 200         int             valuelen;       /* number of bytes in value */
 201 } xfs_attr_inactive_list_t;
 202
 203
 204 /*========================================================================
 205  * Function prototypes for the kernel.
 206  *========================================================================*/
 207
 208 /*
 209  * Internal routines when attribute fork size < XFS_LITINO(mp).
 210  */
 211 void    xfs_attr_shortform_create(struct xfs_da_args *args);
 212 void    xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff);
 213 int     xfs_attr_shortform_lookup(struct xfs_da_args *args);
 214 int     xfs_attr_shortform_getvalue(struct xfs_da_args *args);
 215 int     xfs_attr_shortform_to_leaf(struct xfs_da_args *args);
 216 int     xfs_attr_shortform_remove(struct xfs_da_args *args);
 217 int     xfs_attr_shortform_list(struct xfs_attr_list_context *context);
 218 int     xfs_attr_shortform_allfit(struct xfs_dabuf *bp, struct xfs_inode *dp);
 219 int     xfs_attr_shortform_bytesfit(xfs_inode_t *dp, int bytes);
 220
 221
 222 /*
 223  * Internal routines when attribute fork size == XFS_LBSIZE(mp).
 224  */
 225 int     xfs_attr_leaf_to_node(struct xfs_da_args *args);
 226 int     xfs_attr_leaf_to_shortform(struct xfs_dabuf *bp,
 227                                    struct xfs_da_args *args, int forkoff);
 228 int     xfs_attr_leaf_clearflag(struct xfs_da_args *args);
 229 int     xfs_attr_leaf_setflag(struct xfs_da_args *args);
 230 int     xfs_attr_leaf_flipflags(xfs_da_args_t *args);
 231
 232 /*
 233  * Routines used for growing the Btree.
 234  */
 235 int     xfs_attr_leaf_split(struct xfs_da_state *state,
 236                                    struct xfs_da_state_blk *oldblk,
 237                                    struct xfs_da_state_blk *newblk);
 238 int     xfs_attr_leaf_lookup_int(struct xfs_dabuf *leaf,
 239                                         struct xfs_da_args *args);
 240 int     xfs_attr_leaf_getvalue(struct xfs_dabuf *bp, struct xfs_da_args *args);
 241 int     xfs_attr_leaf_add(struct xfs_dabuf *leaf_buffer,
 242                                  struct xfs_da_args *args);
 243 int     xfs_attr_leaf_remove(struct xfs_dabuf *leaf_buffer,
 244                                     struct xfs_da_args *args);
 245 int     xfs_attr_leaf_list_int(struct xfs_dabuf *bp,
 246                                       struct xfs_attr_list_context *context);
 247
 248 /*
 249  * Routines used for shrinking the Btree.
 250  */
 251 int     xfs_attr_leaf_toosmall(struct xfs_da_state *state, int *retval);
 252 void    xfs_attr_leaf_unbalance(struct xfs_da_state *state,
 253                                        struct xfs_da_state_blk *drop_blk,
 254                                        struct xfs_da_state_blk *save_blk);
 255 int     xfs_attr_root_inactive(struct xfs_trans **trans, struct xfs_inode *dp);
 256
 257 /*
 258  * Utility routines.
 259  */
 260 xfs_dahash_t    xfs_attr_leaf_lasthash(struct xfs_dabuf *bp, int *count);
 261 int     xfs_attr_leaf_order(struct xfs_dabuf *leaf1_bp,
 262                                    struct xfs_dabuf *leaf2_bp);
 263 int     xfs_attr_leaf_newentsize(int namelen, int valuelen, int blocksize,
 264                                         int *local);
 265 #endif  /* __XFS_ATTR_LEAF_H__ */