sys/sys/namecache.h

   1 /*
   2  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * Copyright (c) 1989, 1993
  35  *      The Regents of the University of California.  All rights reserved.
  36  *
  37  * Redistribution and use in source and binary forms, with or without
  38  * modification, are permitted provided that the following conditions
  39  * are met:
  40  * 1. Redistributions of source code must retain the above copyright
  41  *    notice, this list of conditions and the following disclaimer.
  42  * 2. Redistributions in binary form must reproduce the above copyright
  43  *    notice, this list of conditions and the following disclaimer in the
  44  *    documentation and/or other materials provided with the distribution.
  45  * 3. All advertising materials mentioning features or use of this software
  46  *    must display the following acknowledgement:
  47  *      This product includes software developed by the University of
  48  *      California, Berkeley and its contributors.
  49  * 4. Neither the name of the University nor the names of its contributors
  50  *    may be used to endorse or promote products derived from this software
  51  *    without specific prior written permission.
  52  *
  53  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  54  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  55  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  56  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  57  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  58  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  59  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  60  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  61  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  62  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  63  * SUCH DAMAGE.
  64  *
  65  * $DragonFly: src/sys/sys/namecache.h,v 1.31 2008/05/09 17:52:18 dillon Exp $
  66  */
  67
  68 #ifndef _SYS_NAMECACHE_H_
  69 #define _SYS_NAMECACHE_H_
  70
  71 #ifndef _SYS_TYPES_H_
  72 #include <sys/types.h>
  73 #endif
  74 #ifndef _SYS_QUEUE_H_
  75 #include <sys/queue.h>
  76 #endif
  77 #ifndef _SYS_SPINLOCK_H_
  78 #include <sys/spinlock.h>
  79 #endif
  80 #ifndef _SYS_THREAD_H_
  81 #include <sys/thread.h>
  82 #endif
  83
  84 struct vnode;
  85 struct ucred;
  86 struct proc;
  87
  88 TAILQ_HEAD(namecache_list, namecache);
  89
  90 /*
  91  * The namecache structure is used to manage the filesystem namespace.  Most
  92  * vnodes cached by the system will reference one or more associated namecache
  93  * structures.
  94  *
  95  * The DragonFly namecache maintains elements from active nodes to the root
  96  * in all but the NFS server case and the removed file/directory case.
  97  * NFS servers use fhtovp() and may have to regenerate the topology to
  98  * the leaf on the fly.
  99  *
 100  * Because the namecache structure maintains the path through mount points,
 101  * null, and union mounts, and other VFS overlays, several namecache
 102  * structures may pass through the same vnode.  Also note that namespaces
 103  * relating to non-existant (i.e. not-yet-created) files/directories may be
 104  * locked.  Lock coherency is achieved by requiring that the particular
 105  * namecache record whos parent represents the physical directory in which
 106  * the namespace operation is to occur be the one that is locked.  In
 107  * overlay cases, the (union, nullfs) VFS, or in namei when crossing a mount
 108  * point, may have to obtain multiple namespace record locks to avoid
 109  * confusion, but only the one representing the physical directory is passed
 110  * into lower layer VOP calls.
 111  *
 112  * ncp locking is done using atomic ops on nc_exlocks, including a request
 113  * flag for waiters.  nc_locktd is set after locking or cleared before
 114  * the last unlock.  ncp locks are reentrant.
 115  *
 116  * Many new API VOP operations do not pass vnodes.  In these cases the
 117  * operations vector is typically obtained via nc_mount->mnt_vn_use_ops.
 118  */
 119 struct namecache {
 120     LIST_ENTRY(namecache) nc_hash;      /* hash chain (nc_parent,name) */
 121     TAILQ_ENTRY(namecache) nc_entry;    /* scan via nc_parent->nc_list */
 122     TAILQ_ENTRY(namecache) nc_vnode;    /* scan via vnode->v_namecache */
 123     struct namecache_list  nc_list;     /* list of children */
 124     struct nchash_head  *nc_head;
 125     struct namecache    *nc_parent;     /* namecache entry for parent */
 126     struct vnode        *nc_vp;         /* vnode representing name or NULL */
 127     int                 nc_refs;        /* ref count prevents deletion */
 128     u_short             nc_flag;
 129     u_char              nc_nlen;        /* The length of the name, 255 max */
 130     u_char              nc_unused;
 131     char                *nc_name;       /* Separately allocated seg name */
 132     int                 nc_error;
 133     int                 nc_timeout;     /* compared against ticks, or 0 */
 134     u_int               nc_exlocks;     /* namespace locking */
 135     struct thread       *nc_locktd;     /* namespace locking */
 136     long                nc_namecache_gen; /* cmp against mnt_namecache_gen */
 137 };
 138
 139 /*
 140  * Namecache handles include a mount reference allowing topologies
 141  * to be replicated with mount overlays (nullfs mounts).
 142  */
 143 struct nchandle {
 144     struct namecache *ncp;              /* ncp in underlying filesystem */
 145     struct mount *mount;                /* mount pt (possible overlay) */
 146 };
 147
 148 #define ASSERT_NCH_LOCKED(nch)  KKASSERT(nch->ncp->nc_locktd == curthread)
 149
 150 /*
 151  * Flags in namecache.nc_flag (u_char)
 152  */
 153 #define NCF_UNUSED01    0x0001
 154 #define NCF_WHITEOUT    0x0002  /* negative entry corresponds to whiteout */
 155 #define NCF_UNRESOLVED  0x0004  /* invalid or unresolved entry */
 156 #define NCF_ISMOUNTPT   0x0008  /* someone may have mounted on us here */
 157 #define NCF_UNUSED10    0x0010
 158 #define NCF_UNUSED20    0x0020
 159 #define NCF_UNUSED40    0x0040
 160 #define NCF_UNUSED80    0x0080
 161 #define NCF_ISSYMLINK   0x0100  /* represents a symlink */
 162 #define NCF_ISDIR       0x0200  /* represents a directory */
 163 #define NCF_DESTROYED   0x0400  /* name association is considered destroyed */
 164 #define NCF_DEFEREDZAP  0x0800  /* zap defered due to lock unavailability */
 165
 166 #define NC_EXLOCK_REQ   0x80000000      /* ex_lock state */
 167
 168 /*
 169  * cache_inval[_vp]() flags
 170  */
 171 #define CINV_DESTROY    0x0001  /* flag so cache_nlookup ignores the ncp */
 172 #define CINV_UNUSED02   0x0002
 173 #define CINV_CHILDREN   0x0004  /* recursively set children to unresolved */
 174
 175 /*
 176  * MP lock helper for namecache.
 177  *
 178  * CACHE_GETMPLOCK1() Conditionally gets the MP lock if cache_mpsafe
 179  *                    is not set, otherwise does not.
 180  *
 181  * CACHE_GETMPLOCK2() Unconditionally gets the MP lock if it is not already
 182  *                    held (e.g. from GETMPLOCK1).
 183  *
 184  * CACHE_RELMPLOCK()  Releases the MP lock if it was previously acquired
 185  *                    by GETMPLOCK1 or GETMPLOCK2.
 186  */
 187 #define CACHE_MPLOCK_DECLARE            int have_mplock
 188
 189 #define CACHE_GETMPLOCK1()                                              \
 190                 do {                                                    \
 191                         if (cache_mpsafe) {                             \
 192                                 have_mplock = 0;                        \
 193                         } else {                                        \
 194                                 get_mplock();                           \
 195                                 have_mplock = 1;                        \
 196                         }                                               \
 197                 } while (0)
 198
 199 #define CACHE_GETMPLOCK2()                                              \
 200                 do {                                                    \
 201                         if (have_mplock == 0) {                         \
 202                                 have_mplock = 1;                        \
 203                                 get_mplock();                           \
 204                         }                                               \
 205                 } while(0)
 206
 207 #define CACHE_RELMPLOCK()                                               \
 208                 do {                                                    \
 209                         if (have_mplock) {                              \
 210                                 have_mplock = 0;                        \
 211                                 rel_mplock();                           \
 212                         }                                               \
 213                 } while(0)
 214
 215 #ifdef _KERNEL
 216
 217 extern int cache_mpsafe;
 218
 219 struct componentname;
 220 struct nlcomponent;
 221 struct mount;
 222
 223 void    cache_lock(struct nchandle *nch);
 224 void    cache_relock(struct nchandle *nch1, struct ucred *cred1,
 225                         struct nchandle *nch2, struct ucred *cred2);
 226 int     cache_lock_nonblock(struct nchandle *nch);
 227 void    cache_unlock(struct nchandle *nch);
 228 void    cache_setvp(struct nchandle *nch, struct vnode *vp);
 229 void    cache_settimeout(struct nchandle *nch, int nticks);
 230 void    cache_setunresolved(struct nchandle *nch);
 231 void    cache_clrmountpt(struct nchandle *nch);
 232 struct nchandle cache_nlookup(struct nchandle *nch, struct nlcomponent *nlc);
 233 struct nchandle cache_nlookup_nonblock(struct nchandle *nch,
 234                         struct nlcomponent *nlc);
 235 void    cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp);
 236 struct mount *cache_findmount(struct nchandle *nch);
 237 int     cache_inval(struct nchandle *nch, int flags);
 238 int     cache_inval_vp(struct vnode *vp, int flags);
 239 int     cache_inval_vp_nonblock(struct vnode *vp);
 240 void    vfs_cache_setroot(struct vnode *vp, struct nchandle *nch);
 241
 242 int     cache_resolve(struct nchandle *nch, struct ucred *cred);
 243 void    cache_purge(struct vnode *vp);
 244 void    cache_purgevfs (struct mount *mp);
 245 int     cache_get_nonblock(struct nchandle *nch, struct nchandle *target);
 246 void    cache_hysteresis(void);
 247 void    cache_get(struct nchandle *nch, struct nchandle *target);
 248 struct nchandle *cache_hold(struct nchandle *nch);
 249 void    cache_copy(struct nchandle *nch, struct nchandle *target);
 250 void    cache_changemount(struct nchandle *nch, struct mount *mp);
 251 void    cache_put(struct nchandle *nch);
 252 void    cache_drop(struct nchandle *nch);
 253 void    cache_zero(struct nchandle *nch);
 254 void    cache_rename(struct nchandle *fnch, struct nchandle *tnch);
 255 int     cache_vget(struct nchandle *, struct ucred *, int, struct vnode **);
 256 int     cache_vref(struct nchandle *, struct ucred *, struct vnode **);
 257 int     cache_fromdvp(struct vnode *, struct ucred *, int, struct nchandle *);
 258 int     cache_fullpath(struct proc *, struct nchandle *, char **, char **);
 259
 260 #endif
 261
 262 #endif