fs/nfsd/nfsd.h

   1 /*
   2  * Hodge-podge collection of knfsd-related stuff.
   3  * I will sort this out later.
   4  *
   5  * Copyright (C) 1995-1997 Olaf Kirch <okir@monad.swb.de>
   6  */
   7
   8 #ifndef LINUX_NFSD_NFSD_H
   9 #define LINUX_NFSD_NFSD_H
  10
  11 #include <linux/types.h>
  12 #include <linux/mount.h>
  13
  14 #include <linux/nfs.h>
  15 #include <linux/nfs2.h>
  16 #include <linux/nfs3.h>
  17 #include <linux/nfs4.h>
  18 #include <linux/sunrpc/msg_prot.h>
  19
  20 #include <linux/nfsd/debug.h>
  21 #include <linux/nfsd/export.h>
  22 #include <linux/nfsd/stats.h>
  23
  24 /*
  25  * nfsd version
  26  */
  27 #define NFSD_SUPPORTED_MINOR_VERSION    1
  28 /*
  29  * Maximum blocksizes supported by daemon under various circumstances.
  30  */
  31 #define NFSSVC_MAXBLKSIZE       RPCSVC_MAXPAYLOAD
  32 /* NFSv2 is limited by the protocol specification, see RFC 1094 */
  33 #define NFSSVC_MAXBLKSIZE_V2    (8*1024)
  34
  35
  36 /*
  37  * Largest number of bytes we need to allocate for an NFS
  38  * call or reply.  Used to control buffer sizes.  We use
  39  * the length of v3 WRITE, READDIR and READDIR replies
  40  * which are an RPC header, up to 26 XDR units of reply
  41  * data, and some page data.
  42  *
  43  * Note that accuracy here doesn't matter too much as the
  44  * size is rounded up to a page size when allocating space.
  45  */
  46 #define NFSD_BUFSIZE            ((RPC_MAX_HEADER_WITH_AUTH+26)*XDR_UNIT + NFSSVC_MAXBLKSIZE)
  47
  48 struct readdir_cd {
  49         __be32                  err;    /* 0, nfserr, or nfserr_eof */
  50 };
  51
  52
  53 extern struct svc_program       nfsd_program;
  54 extern struct svc_version       nfsd_version2, nfsd_version3,
  55                                 nfsd_version4;
  56 extern u32                      nfsd_supported_minorversion;
  57 extern struct mutex             nfsd_mutex;
  58 extern struct svc_serv          *nfsd_serv;
  59 extern spinlock_t               nfsd_drc_lock;
  60 extern unsigned int             nfsd_drc_max_mem;
  61 extern unsigned int             nfsd_drc_mem_used;
  62
  63 extern const struct seq_operations nfs_exports_op;
  64
  65 /*
  66  * Function prototypes.
  67  */
  68 int             nfsd_svc(unsigned short port, int nrservs);
  69 int             nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp);
  70
  71 int             nfsd_nrthreads(void);
  72 int             nfsd_nrpools(void);
  73 int             nfsd_get_nrthreads(int n, int *);
  74 int             nfsd_set_nrthreads(int n, int *);
  75
  76 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
  77 #ifdef CONFIG_NFSD_V2_ACL
  78 extern struct svc_version nfsd_acl_version2;
  79 #else
  80 #define nfsd_acl_version2 NULL
  81 #endif
  82 #ifdef CONFIG_NFSD_V3_ACL
  83 extern struct svc_version nfsd_acl_version3;
  84 #else
  85 #define nfsd_acl_version3 NULL
  86 #endif
  87 #endif
  88
  89 enum vers_op {NFSD_SET, NFSD_CLEAR, NFSD_TEST, NFSD_AVAIL };
  90 int nfsd_vers(int vers, enum vers_op change);
  91 int nfsd_minorversion(u32 minorversion, enum vers_op change);
  92 void nfsd_reset_versions(void);
  93 int nfsd_create_serv(void);
  94
  95 extern int nfsd_max_blksize;
  96
  97 static inline int nfsd_v4client(struct svc_rqst *rq)
  98 {
  99         return rq->rq_prog == NFS_PROGRAM && rq->rq_vers == 4;
 100 }
 101
 102 /*
 103  * NFSv4 State
 104  */
 105 #ifdef CONFIG_NFSD_V4
 106 extern unsigned int max_delegations;
 107 int nfs4_state_init(void);
 108 void nfsd4_free_slabs(void);
 109 int nfs4_state_start(void);
 110 void nfs4_state_shutdown(void);
 111 void nfs4_reset_lease(time_t leasetime);
 112 int nfs4_reset_recoverydir(char *recdir);
 113 #else
 114 static inline int nfs4_state_init(void) { return 0; }
 115 static inline void nfsd4_free_slabs(void) { }
 116 static inline int nfs4_state_start(void) { return 0; }
 117 static inline void nfs4_state_shutdown(void) { }
 118 static inline void nfs4_reset_lease(time_t leasetime) { }
 119 static inline int nfs4_reset_recoverydir(char *recdir) { return 0; }
 120 #endif
 121
 122 /*
 123  * lockd binding
 124  */
 125 void            nfsd_lockd_init(void);
 126 void            nfsd_lockd_shutdown(void);
 127
 128
 129 /*
 130  * These macros provide pre-xdr'ed values for faster operation.
 131  */
 132 #define nfs_ok                  cpu_to_be32(NFS_OK)
 133 #define nfserr_perm             cpu_to_be32(NFSERR_PERM)
 134 #define nfserr_noent            cpu_to_be32(NFSERR_NOENT)
 135 #define nfserr_io               cpu_to_be32(NFSERR_IO)
 136 #define nfserr_nxio             cpu_to_be32(NFSERR_NXIO)
 137 #define nfserr_eagain           cpu_to_be32(NFSERR_EAGAIN)
 138 #define nfserr_acces            cpu_to_be32(NFSERR_ACCES)
 139 #define nfserr_exist            cpu_to_be32(NFSERR_EXIST)
 140 #define nfserr_xdev             cpu_to_be32(NFSERR_XDEV)
 141 #define nfserr_nodev            cpu_to_be32(NFSERR_NODEV)
 142 #define nfserr_notdir           cpu_to_be32(NFSERR_NOTDIR)
 143 #define nfserr_isdir            cpu_to_be32(NFSERR_ISDIR)
 144 #define nfserr_inval            cpu_to_be32(NFSERR_INVAL)
 145 #define nfserr_fbig             cpu_to_be32(NFSERR_FBIG)
 146 #define nfserr_nospc            cpu_to_be32(NFSERR_NOSPC)
 147 #define nfserr_rofs             cpu_to_be32(NFSERR_ROFS)
 148 #define nfserr_mlink            cpu_to_be32(NFSERR_MLINK)
 149 #define nfserr_opnotsupp        cpu_to_be32(NFSERR_OPNOTSUPP)
 150 #define nfserr_nametoolong      cpu_to_be32(NFSERR_NAMETOOLONG)
 151 #define nfserr_notempty         cpu_to_be32(NFSERR_NOTEMPTY)
 152 #define nfserr_dquot            cpu_to_be32(NFSERR_DQUOT)
 153 #define nfserr_stale            cpu_to_be32(NFSERR_STALE)
 154 #define nfserr_remote           cpu_to_be32(NFSERR_REMOTE)
 155 #define nfserr_wflush           cpu_to_be32(NFSERR_WFLUSH)
 156 #define nfserr_badhandle        cpu_to_be32(NFSERR_BADHANDLE)
 157 #define nfserr_notsync          cpu_to_be32(NFSERR_NOT_SYNC)
 158 #define nfserr_badcookie        cpu_to_be32(NFSERR_BAD_COOKIE)
 159 #define nfserr_notsupp          cpu_to_be32(NFSERR_NOTSUPP)
 160 #define nfserr_toosmall         cpu_to_be32(NFSERR_TOOSMALL)
 161 #define nfserr_serverfault      cpu_to_be32(NFSERR_SERVERFAULT)
 162 #define nfserr_badtype          cpu_to_be32(NFSERR_BADTYPE)
 163 #define nfserr_jukebox          cpu_to_be32(NFSERR_JUKEBOX)
 164 #define nfserr_denied           cpu_to_be32(NFSERR_DENIED)
 165 #define nfserr_deadlock         cpu_to_be32(NFSERR_DEADLOCK)
 166 #define nfserr_expired          cpu_to_be32(NFSERR_EXPIRED)
 167 #define nfserr_bad_cookie       cpu_to_be32(NFSERR_BAD_COOKIE)
 168 #define nfserr_same             cpu_to_be32(NFSERR_SAME)
 169 #define nfserr_clid_inuse       cpu_to_be32(NFSERR_CLID_INUSE)
 170 #define nfserr_stale_clientid   cpu_to_be32(NFSERR_STALE_CLIENTID)
 171 #define nfserr_resource         cpu_to_be32(NFSERR_RESOURCE)
 172 #define nfserr_moved            cpu_to_be32(NFSERR_MOVED)
 173 #define nfserr_nofilehandle     cpu_to_be32(NFSERR_NOFILEHANDLE)
 174 #define nfserr_minor_vers_mismatch      cpu_to_be32(NFSERR_MINOR_VERS_MISMATCH)
 175 #define nfserr_share_denied     cpu_to_be32(NFSERR_SHARE_DENIED)
 176 #define nfserr_stale_stateid    cpu_to_be32(NFSERR_STALE_STATEID)
 177 #define nfserr_old_stateid      cpu_to_be32(NFSERR_OLD_STATEID)
 178 #define nfserr_bad_stateid      cpu_to_be32(NFSERR_BAD_STATEID)
 179 #define nfserr_bad_seqid        cpu_to_be32(NFSERR_BAD_SEQID)
 180 #define nfserr_symlink          cpu_to_be32(NFSERR_SYMLINK)
 181 #define nfserr_not_same         cpu_to_be32(NFSERR_NOT_SAME)
 182 #define nfserr_lock_range       cpu_to_be32(NFSERR_LOCK_RANGE)
 183 #define nfserr_restorefh        cpu_to_be32(NFSERR_RESTOREFH)
 184 #define nfserr_attrnotsupp      cpu_to_be32(NFSERR_ATTRNOTSUPP)
 185 #define nfserr_bad_xdr          cpu_to_be32(NFSERR_BAD_XDR)
 186 #define nfserr_openmode         cpu_to_be32(NFSERR_OPENMODE)
 187 #define nfserr_badowner         cpu_to_be32(NFSERR_BADOWNER)
 188 #define nfserr_locks_held       cpu_to_be32(NFSERR_LOCKS_HELD)
 189 #define nfserr_op_illegal       cpu_to_be32(NFSERR_OP_ILLEGAL)
 190 #define nfserr_grace            cpu_to_be32(NFSERR_GRACE)
 191 #define nfserr_no_grace         cpu_to_be32(NFSERR_NO_GRACE)
 192 #define nfserr_reclaim_bad      cpu_to_be32(NFSERR_RECLAIM_BAD)
 193 #define nfserr_badname          cpu_to_be32(NFSERR_BADNAME)
 194 #define nfserr_cb_path_down     cpu_to_be32(NFSERR_CB_PATH_DOWN)
 195 #define nfserr_locked           cpu_to_be32(NFSERR_LOCKED)
 196 #define nfserr_wrongsec         cpu_to_be32(NFSERR_WRONGSEC)
 197 #define nfserr_badiomode                cpu_to_be32(NFS4ERR_BADIOMODE)
 198 #define nfserr_badlayout                cpu_to_be32(NFS4ERR_BADLAYOUT)
 199 #define nfserr_bad_session_digest       cpu_to_be32(NFS4ERR_BAD_SESSION_DIGEST)
 200 #define nfserr_badsession               cpu_to_be32(NFS4ERR_BADSESSION)
 201 #define nfserr_badslot                  cpu_to_be32(NFS4ERR_BADSLOT)
 202 #define nfserr_complete_already         cpu_to_be32(NFS4ERR_COMPLETE_ALREADY)
 203 #define nfserr_conn_not_bound_to_session cpu_to_be32(NFS4ERR_CONN_NOT_BOUND_TO_SESSION)
 204 #define nfserr_deleg_already_wanted     cpu_to_be32(NFS4ERR_DELEG_ALREADY_WANTED)
 205 #define nfserr_back_chan_busy           cpu_to_be32(NFS4ERR_BACK_CHAN_BUSY)
 206 #define nfserr_layouttrylater           cpu_to_be32(NFS4ERR_LAYOUTTRYLATER)
 207 #define nfserr_layoutunavailable        cpu_to_be32(NFS4ERR_LAYOUTUNAVAILABLE)
 208 #define nfserr_nomatching_layout        cpu_to_be32(NFS4ERR_NOMATCHING_LAYOUT)
 209 #define nfserr_recallconflict           cpu_to_be32(NFS4ERR_RECALLCONFLICT)
 210 #define nfserr_unknown_layouttype       cpu_to_be32(NFS4ERR_UNKNOWN_LAYOUTTYPE)
 211 #define nfserr_seq_misordered           cpu_to_be32(NFS4ERR_SEQ_MISORDERED)
 212 #define nfserr_sequence_pos             cpu_to_be32(NFS4ERR_SEQUENCE_POS)
 213 #define nfserr_req_too_big              cpu_to_be32(NFS4ERR_REQ_TOO_BIG)
 214 #define nfserr_rep_too_big              cpu_to_be32(NFS4ERR_REP_TOO_BIG)
 215 #define nfserr_rep_too_big_to_cache     cpu_to_be32(NFS4ERR_REP_TOO_BIG_TO_CACHE)
 216 #define nfserr_retry_uncached_rep       cpu_to_be32(NFS4ERR_RETRY_UNCACHED_REP)
 217 #define nfserr_unsafe_compound          cpu_to_be32(NFS4ERR_UNSAFE_COMPOUND)
 218 #define nfserr_too_many_ops             cpu_to_be32(NFS4ERR_TOO_MANY_OPS)
 219 #define nfserr_op_not_in_session        cpu_to_be32(NFS4ERR_OP_NOT_IN_SESSION)
 220 #define nfserr_hash_alg_unsupp          cpu_to_be32(NFS4ERR_HASH_ALG_UNSUPP)
 221 #define nfserr_clientid_busy            cpu_to_be32(NFS4ERR_CLIENTID_BUSY)
 222 #define nfserr_pnfs_io_hole             cpu_to_be32(NFS4ERR_PNFS_IO_HOLE)
 223 #define nfserr_seq_false_retry          cpu_to_be32(NFS4ERR_SEQ_FALSE_RETRY)
 224 #define nfserr_bad_high_slot            cpu_to_be32(NFS4ERR_BAD_HIGH_SLOT)
 225 #define nfserr_deadsession              cpu_to_be32(NFS4ERR_DEADSESSION)
 226 #define nfserr_encr_alg_unsupp          cpu_to_be32(NFS4ERR_ENCR_ALG_UNSUPP)
 227 #define nfserr_pnfs_no_layout           cpu_to_be32(NFS4ERR_PNFS_NO_LAYOUT)
 228 #define nfserr_not_only_op              cpu_to_be32(NFS4ERR_NOT_ONLY_OP)
 229 #define nfserr_wrong_cred               cpu_to_be32(NFS4ERR_WRONG_CRED)
 230 #define nfserr_wrong_type               cpu_to_be32(NFS4ERR_WRONG_TYPE)
 231 #define nfserr_dirdeleg_unavail         cpu_to_be32(NFS4ERR_DIRDELEG_UNAVAIL)
 232 #define nfserr_reject_deleg             cpu_to_be32(NFS4ERR_REJECT_DELEG)
 233 #define nfserr_returnconflict           cpu_to_be32(NFS4ERR_RETURNCONFLICT)
 234 #define nfserr_deleg_revoked            cpu_to_be32(NFS4ERR_DELEG_REVOKED)
 235
 236 /* error codes for internal use */
 237 /* if a request fails due to kmalloc failure, it gets dropped.
 238  *  Client should resend eventually
 239  */
 240 #define nfserr_dropit           cpu_to_be32(30000)
 241 /* end-of-file indicator in readdir */
 242 #define nfserr_eof              cpu_to_be32(30001)
 243 /* replay detected */
 244 #define nfserr_replay_me        cpu_to_be32(11001)
 245 /* nfs41 replay detected */
 246 #define nfserr_replay_cache     cpu_to_be32(11002)
 247
 248 /* Check for dir entries '.' and '..' */
 249 #define isdotent(n, l)  (l < 3 && n[0] == '.' && (l == 1 || n[1] == '.'))
 250
 251 /*
 252  * Time of server startup
 253  */
 254 extern struct timeval   nfssvc_boot;
 255
 256 #ifdef CONFIG_NFSD_V4
 257
 258 extern time_t nfsd4_lease;
 259 extern time_t nfsd4_grace;
 260
 261 /* before processing a COMPOUND operation, we have to check that there
 262  * is enough space in the buffer for XDR encode to succeed.  otherwise,
 263  * we might process an operation with side effects, and be unable to
 264  * tell the client that the operation succeeded.
 265  *
 266  * COMPOUND_SLACK_SPACE - this is the minimum bytes of buffer space
 267  * needed to encode an "ordinary" _successful_ operation.  (GETATTR,
 268  * READ, READDIR, and READLINK have their own buffer checks.)  if we
 269  * fall below this level, we fail the next operation with NFS4ERR_RESOURCE.
 270  *
 271  * COMPOUND_ERR_SLACK_SPACE - this is the minimum bytes of buffer space
 272  * needed to encode an operation which has failed with NFS4ERR_RESOURCE.
 273  * care is taken to ensure that we never fall below this level for any
 274  * reason.
 275  */
 276 #define COMPOUND_SLACK_SPACE            140    /* OP_GETFH */
 277 #define COMPOUND_ERR_SLACK_SPACE        12     /* OP_SETATTR */
 278
 279 #define NFSD_LAUNDROMAT_MINTIMEOUT      1   /* seconds */
 280
 281 /*
 282  * The following attributes are currently not supported by the NFSv4 server:
 283  *    ARCHIVE       (deprecated anyway)
 284  *    HIDDEN        (unlikely to be supported any time soon)
 285  *    MIMETYPE      (unlikely to be supported any time soon)
 286  *    QUOTA_*       (will be supported in a forthcoming patch)
 287  *    SYSTEM        (unlikely to be supported any time soon)
 288  *    TIME_BACKUP   (unlikely to be supported any time soon)
 289  *    TIME_CREATE   (unlikely to be supported any time soon)
 290  */
 291 #define NFSD4_SUPPORTED_ATTRS_WORD0                                                         \
 292 (FATTR4_WORD0_SUPPORTED_ATTRS   | FATTR4_WORD0_TYPE         | FATTR4_WORD0_FH_EXPIRE_TYPE   \
 293  | FATTR4_WORD0_CHANGE          | FATTR4_WORD0_SIZE         | FATTR4_WORD0_LINK_SUPPORT     \
 294  | FATTR4_WORD0_SYMLINK_SUPPORT | FATTR4_WORD0_NAMED_ATTR   | FATTR4_WORD0_FSID             \
 295  | FATTR4_WORD0_UNIQUE_HANDLES  | FATTR4_WORD0_LEASE_TIME   | FATTR4_WORD0_RDATTR_ERROR     \
 296  | FATTR4_WORD0_ACLSUPPORT      | FATTR4_WORD0_CANSETTIME   | FATTR4_WORD0_CASE_INSENSITIVE \
 297  | FATTR4_WORD0_CASE_PRESERVING | FATTR4_WORD0_CHOWN_RESTRICTED                             \
 298  | FATTR4_WORD0_FILEHANDLE      | FATTR4_WORD0_FILEID       | FATTR4_WORD0_FILES_AVAIL      \
 299  | FATTR4_WORD0_FILES_FREE      | FATTR4_WORD0_FILES_TOTAL  | FATTR4_WORD0_FS_LOCATIONS | FATTR4_WORD0_HOMOGENEOUS      \
 300  | FATTR4_WORD0_MAXFILESIZE     | FATTR4_WORD0_MAXLINK      | FATTR4_WORD0_MAXNAME          \
 301  | FATTR4_WORD0_MAXREAD         | FATTR4_WORD0_MAXWRITE     | FATTR4_WORD0_ACL)
 302
 303 #define NFSD4_SUPPORTED_ATTRS_WORD1                                                         \
 304 (FATTR4_WORD1_MODE              | FATTR4_WORD1_NO_TRUNC     | FATTR4_WORD1_NUMLINKS         \
 305  | FATTR4_WORD1_OWNER           | FATTR4_WORD1_OWNER_GROUP  | FATTR4_WORD1_RAWDEV           \
 306  | FATTR4_WORD1_SPACE_AVAIL     | FATTR4_WORD1_SPACE_FREE   | FATTR4_WORD1_SPACE_TOTAL      \
 307  | FATTR4_WORD1_SPACE_USED      | FATTR4_WORD1_TIME_ACCESS  | FATTR4_WORD1_TIME_ACCESS_SET  \
 308  | FATTR4_WORD1_TIME_DELTA   | FATTR4_WORD1_TIME_METADATA    \
 309  | FATTR4_WORD1_TIME_MODIFY     | FATTR4_WORD1_TIME_MODIFY_SET | FATTR4_WORD1_MOUNTED_ON_FILEID)
 310
 311 #define NFSD4_SUPPORTED_ATTRS_WORD2 0
 312
 313 #define NFSD4_1_SUPPORTED_ATTRS_WORD0 \
 314         NFSD4_SUPPORTED_ATTRS_WORD0
 315
 316 #define NFSD4_1_SUPPORTED_ATTRS_WORD1 \
 317         NFSD4_SUPPORTED_ATTRS_WORD1
 318
 319 #define NFSD4_1_SUPPORTED_ATTRS_WORD2 \
 320         (NFSD4_SUPPORTED_ATTRS_WORD2 | FATTR4_WORD2_SUPPATTR_EXCLCREAT)
 321
 322 static inline u32 nfsd_suppattrs0(u32 minorversion)
 323 {
 324         return minorversion ? NFSD4_1_SUPPORTED_ATTRS_WORD0
 325                             : NFSD4_SUPPORTED_ATTRS_WORD0;
 326 }
 327
 328 static inline u32 nfsd_suppattrs1(u32 minorversion)
 329 {
 330         return minorversion ? NFSD4_1_SUPPORTED_ATTRS_WORD1
 331                             : NFSD4_SUPPORTED_ATTRS_WORD1;
 332 }
 333
 334 static inline u32 nfsd_suppattrs2(u32 minorversion)
 335 {
 336         return minorversion ? NFSD4_1_SUPPORTED_ATTRS_WORD2
 337                             : NFSD4_SUPPORTED_ATTRS_WORD2;
 338 }
 339
 340 /* These will return ERR_INVAL if specified in GETATTR or READDIR. */
 341 #define NFSD_WRITEONLY_ATTRS_WORD1                                                          \
 342 (FATTR4_WORD1_TIME_ACCESS_SET   | FATTR4_WORD1_TIME_MODIFY_SET)
 343
 344 /* These are the only attrs allowed in CREATE/OPEN/SETATTR. */
 345 #define NFSD_WRITEABLE_ATTRS_WORD0                                                          \
 346 (FATTR4_WORD0_SIZE              | FATTR4_WORD0_ACL                                         )
 347 #define NFSD_WRITEABLE_ATTRS_WORD1                                                          \
 348 (FATTR4_WORD1_MODE              | FATTR4_WORD1_OWNER         | FATTR4_WORD1_OWNER_GROUP     \
 349  | FATTR4_WORD1_TIME_ACCESS_SET | FATTR4_WORD1_TIME_MODIFY_SET)
 350 #define NFSD_WRITEABLE_ATTRS_WORD2 0
 351
 352 #define NFSD_SUPPATTR_EXCLCREAT_WORD0 \
 353         NFSD_WRITEABLE_ATTRS_WORD0
 354 /*
 355  * we currently store the exclusive create verifier in the v_{a,m}time
 356  * attributes so the client can't set these at create time using EXCLUSIVE4_1
 357  */
 358 #define NFSD_SUPPATTR_EXCLCREAT_WORD1 \
 359         (NFSD_WRITEABLE_ATTRS_WORD1 & \
 360          ~(FATTR4_WORD1_TIME_ACCESS_SET | FATTR4_WORD1_TIME_MODIFY_SET))
 361 #define NFSD_SUPPATTR_EXCLCREAT_WORD2 \
 362         NFSD_WRITEABLE_ATTRS_WORD2
 363
 364 extern int nfsd4_is_junction(struct dentry *dentry);
 365 #else
 366 static inline int nfsd4_is_junction(struct dentry *dentry)
 367 {
 368         return 0;
 369 }
 370
 371 #endif /* CONFIG_NFSD_V4 */
 372
 373 #endif /* LINUX_NFSD_NFSD_H */