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. Neither the name of the University nor the names of its contributors
  46  *    may be used to endorse or promote products derived from this software
  47  *    without specific prior written permission.
  48  *
  49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  59  * SUCH DAMAGE.
  60  *
  61  * $DragonFly: src/sys/sys/namecache.h,v 1.31 2008/05/09 17:52:18 dillon Exp $
  62  */
  63
  64 #ifndef _SYS_NAMECACHE_H_
  65 #define _SYS_NAMECACHE_H_
  66
  67 #ifndef _SYS_TYPES_H_
  68 #include <sys/types.h>
  69 #endif
  70 #ifndef _SYS_QUEUE_H_
  71 #include <sys/queue.h>
  72 #endif
  73 #ifndef _SYS_SPINLOCK_H_
  74 #include <sys/spinlock.h>
  75 #endif
  76 #ifndef _SYS_THREAD_H_
  77 #include <sys/thread.h>
  78 #endif
  79
  80 struct vnode;
  81 struct ucred;
  82 struct proc;
  83
  84 TAILQ_HEAD(namecache_list, namecache);
  85
  86 /*
  87  * The namecache structure is used to manage the filesystem namespace.  Most
  88  * vnodes cached by the system will reference one or more associated namecache
  89  * structures.
  90  *
  91  * The DragonFly namecache maintains elements from active nodes to the root
  92  * in all but the NFS server case and the removed file/directory case.
  93  * NFS servers use fhtovp() and may have to regenerate the topology to
  94  * the leaf on the fly.
  95  *
  96  * Because the namecache structure maintains the path through mount points,
  97  * null, and union mounts, and other VFS overlays, several namecache
  98  * structures may pass through the same vnode.  Also note that namespaces
  99  * relating to non-existant (i.e. not-yet-created) files/directories may be
 100  * locked.  Lock coherency is achieved by requiring that the particular
 101  * namecache record whos parent represents the physical directory in which
 102  * the namespace operation is to occur be the one that is locked.  In
 103  * overlay cases, the (union, nullfs) VFS, or in namei when crossing a mount
 104  * point, may have to obtain multiple namespace record locks to avoid
 105  * confusion, but only the one representing the physical directory is passed
 106  * into lower layer VOP calls.
 107  *
 108  * ncp locking is done using atomic ops on nc_lockstatus, including a request
 109  * flag for waiters.  nc_locktd is set after locking or cleared before
 110  * the last unlock.  ncp locks are reentrant.
 111  *
 112  * Many new API VOP operations do not pass vnodes.  In these cases the
 113  * operations vector is typically obtained via nc_mount->mnt_vn_use_ops.
 114  */
 115 struct namecache {
 116     LIST_ENTRY(namecache) nc_hash;      /* hash chain (nc_parent,name) */
 117     TAILQ_ENTRY(namecache) nc_entry;    /* scan via nc_parent->nc_list */
 118     TAILQ_ENTRY(namecache) nc_vnode;    /* scan via vnode->v_namecache */
 119     struct namecache_list  nc_list;     /* list of children */
 120     struct nchash_head  *nc_head;
 121     struct namecache    *nc_parent;     /* namecache entry for parent */
 122     struct vnode        *nc_vp;         /* vnode representing name or NULL */
 123     int                 nc_refs;        /* ref count prevents deletion */
 124     u_short             nc_flag;
 125     u_char              nc_nlen;        /* The length of the name, 255 max */
 126     u_char              nc_unused;
 127     char                *nc_name;       /* Separately allocated seg name */
 128     int                 nc_error;
 129     int                 nc_timeout;     /* compared against ticks, or 0 */
 130     u_int               nc_lockstatus;  /* namespace locking */
 131     struct thread       *nc_locktd;     /* namespace locking */
 132     u_int               nc_namecache_gen; /* mount generation (autoclear) */
 133     u_int               nc_generation;  /* rename/unlink generation */
 134 };
 135
 136 /*
 137  * Namecache handles include a mount reference allowing topologies
 138  * to be replicated with mount overlays (nullfs mounts).
 139  */
 140 struct nchandle {
 141     struct namecache *ncp;              /* ncp in underlying filesystem */
 142     struct mount *mount;                /* mount pt (possible overlay) */
 143 };
 144
 145 /*
 146  * Flags in namecache.nc_flag (u_char)
 147  */
 148 #define NCF_UNUSED01    0x0001
 149 #define NCF_WHITEOUT    0x0002  /* negative entry corresponds to whiteout */
 150 #define NCF_UNRESOLVED  0x0004  /* invalid or unresolved entry */
 151 #define NCF_ISMOUNTPT   0x0008  /* someone may have mounted on us here */
 152 #define NCF_SF_NOCACHE  0x0010  /* track swapcache chflags from attr */
 153 #define NCF_UF_CACHE    0x0020
 154 #define NCF_SF_PNOCACHE 0x0040  /* track from parent */
 155 #define NCF_UF_PCACHE   0x0080
 156 #define NCF_ISSYMLINK   0x0100  /* represents a symlink */
 157 #define NCF_ISDIR       0x0200  /* represents a directory */
 158 #define NCF_DESTROYED   0x0400  /* name association is considered destroyed */
 159 #define NCF_DEFEREDZAP  0x0800  /* zap defered due to lock unavailability */
 160
 161 #define NC_EXLOCK_REQ   0x80000000      /* nc_lockstatus state flag */
 162 #define NC_SHLOCK_REQ   0x40000000      /* nc_lockstatus state flag */
 163 #define NC_SHLOCK_FLAG  0x20000000      /* nc_lockstatus state flag */
 164 #define NC_SHLOCK_VHOLD 0x10000000      /* nc_lockstatus state flag */
 165
 166 /*
 167  * cache_inval[_vp]() flags
 168  */
 169 #define CINV_DESTROY    0x0001  /* flag so cache_nlookup ignores the ncp */
 170 #define CINV_UNUSED02   0x0002
 171 #define CINV_CHILDREN   0x0004  /* recursively set children to unresolved */
 172
 173 #ifdef _KERNEL
 174
 175 struct componentname;
 176 struct nlcomponent;
 177 struct mount;
 178
 179 void    cache_clearmntcache(void);
 180 void    cache_lock(struct nchandle *nch);
 181 void    cache_lock_maybe_shared(struct nchandle *nch, int excl);
 182 void    cache_relock(struct nchandle *nch1, struct ucred *cred1,
 183                         struct nchandle *nch2, struct ucred *cred2);
 184 int     cache_lock_nonblock(struct nchandle *nch);
 185 void    cache_unlock(struct nchandle *nch);
 186 int     cache_lockstatus(struct nchandle *nch);
 187 void    cache_setvp(struct nchandle *nch, struct vnode *vp);
 188 void    cache_settimeout(struct nchandle *nch, int nticks);
 189 void    cache_setunresolved(struct nchandle *nch);
 190 void    cache_clrmountpt(struct nchandle *nch);
 191 struct nchandle cache_nlookup(struct nchandle *nch, struct nlcomponent *nlc);
 192 struct nchandle cache_nlookup_nonblock(struct nchandle *nch,
 193                         struct nlcomponent *nlc);
 194 int     cache_nlookup_maybe_shared(struct nchandle *nch,
 195                         struct nlcomponent *nlc, int excl,
 196                         struct nchandle *nchres);
 197 void    cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp);
 198 struct mount *cache_findmount(struct nchandle *nch);
 199 void    cache_dropmount(struct mount *mp);
 200 void    cache_ismounting(struct mount *mp);
 201 void    cache_unmounting(struct mount *mp);
 202 int     cache_inval(struct nchandle *nch, int flags);
 203 int     cache_inval_vp(struct vnode *vp, int flags);
 204 int     cache_inval_vp_nonblock(struct vnode *vp);
 205 void    vfs_cache_setroot(struct vnode *vp, struct nchandle *nch);
 206
 207 int     cache_resolve(struct nchandle *nch, struct ucred *cred);
 208 void    cache_purge(struct vnode *vp);
 209 void    cache_purgevfs (struct mount *mp);
 210 void    cache_hysteresis(int critpath);
 211 void    cache_get(struct nchandle *nch, struct nchandle *target);
 212 int     cache_get_nonblock(struct nchandle *nch, struct nchandle *target);
 213 void    cache_get_maybe_shared(struct nchandle *nch,
 214                         struct nchandle *target, int excl);
 215 struct nchandle *cache_hold(struct nchandle *nch);
 216 void    cache_copy(struct nchandle *nch, struct nchandle *target);
 217 void    cache_changemount(struct nchandle *nch, struct mount *mp);
 218 void    cache_put(struct nchandle *nch);
 219 void    cache_drop(struct nchandle *nch);
 220 void    cache_drop_and_cache(struct nchandle *nch);
 221 void    cache_zero(struct nchandle *nch);
 222 void    cache_rename(struct nchandle *fnch, struct nchandle *tnch);
 223 void    cache_unlink(struct nchandle *nch);
 224 int     cache_isopen(struct nchandle *nch);
 225 int     cache_vget(struct nchandle *, struct ucred *, int, struct vnode **);
 226 int     cache_vref(struct nchandle *, struct ucred *, struct vnode **);
 227 int     cache_fromdvp(struct vnode *, struct ucred *, int, struct nchandle *);
 228 int     cache_fullpath(struct proc *, struct nchandle *, struct nchandle *,
 229                         char **, char **, int);
 230
 231 #endif
 232
 233 #endif