sys/sys/namecache.h

   1 /*
   2  * Copyright (c) 2003,2004-2019 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
  62 #ifndef _SYS_NAMECACHE_H_
  63 #define _SYS_NAMECACHE_H_
  64
  65 #ifndef _SYS_TYPES_H_
  66 #include <sys/types.h>
  67 #endif
  68 #ifndef _SYS_LOCK_H_
  69 #include <sys/lock.h>
  70 #endif
  71 #ifndef _SYS_QUEUE_H_
  72 #include <sys/queue.h>
  73 #endif
  74 #ifndef _SYS_SPINLOCK_H_
  75 #include <sys/spinlock.h>
  76 #endif
  77
  78 struct vnode;
  79 struct ucred;
  80 struct proc;
  81
  82 TAILQ_HEAD(namecache_list, namecache);
  83
  84 /*
  85  * The namecache structure is used to manage the filesystem namespace.  Most
  86  * vnodes cached by the system will reference one or more associated namecache
  87  * structures.
  88  *
  89  * The DragonFly namecache maintains elements from active nodes to the root
  90  * in all but the NFS server case and the removed file/directory case.
  91  * NFS servers use fhtovp() and may have to regenerate the topology to
  92  * the leaf on the fly.
  93  *
  94  * Because the namecache structure maintains the path through mount points,
  95  * null, and union mounts, and other VFS overlays, several namecache
  96  * structures may pass through the same vnode.  Also note that namespaces
  97  * relating to non-existant (i.e. not-yet-created) files/directories may be
  98  * locked.  Lock coherency is achieved by requiring that the particular
  99  * namecache record whos parent represents the physical directory in which
 100  * the namespace operation is to occur be the one that is locked.  In
 101  * overlay cases, the (union, nullfs) VFS, or in namei when crossing a mount
 102  * point, may have to obtain multiple namespace record locks to avoid
 103  * confusion, but only the one representing the physical directory is passed
 104  * into lower layer VOP calls.
 105  *
 106  * ncp locking is done using atomic ops on nc_lockstatus, including a request
 107  * flag for waiters.  nc_locktd is set after locking or cleared before
 108  * the last unlock.  ncp locks are reentrant.
 109  *
 110  * Many new API VOP operations do not pass vnodes.  In these cases the
 111  * operations vector is typically obtained via nc_mount->mnt_vn_use_ops.
 112  */
 113 struct namecache {
 114     TAILQ_ENTRY(namecache) nc_hash;     /* hash chain (nc_parent,name) */
 115     TAILQ_ENTRY(namecache) nc_entry;    /* scan via nc_parent->nc_list */
 116     TAILQ_ENTRY(namecache) nc_vnode;    /* scan via vnode->v_namecache */
 117     struct namecache_list  nc_list;     /* list of children */
 118     struct nchash_head  *nc_head;
 119     struct namecache    *nc_parent;     /* namecache entry for parent */
 120     struct vnode        *nc_vp;         /* vnode representing name or NULL */
 121     u_short             nc_flag;
 122     u_char              nc_nlen;        /* The length of the name, 255 max */
 123     u_char              nc_unused;
 124     char                *nc_name;       /* Separately allocated seg name */
 125     int                 nc_error;
 126     int                 nc_timeout;     /* compared against ticks, or 0 */
 127     int                 nc_negcpu;      /* which ncneg list are we on? */
 128     struct {
 129             u_int       nc_namecache_gen; /* mount generation (autoclear) */
 130             u_int       nc_generation;  /* rename/unlink generation */
 131             int         nc_refs;        /* ref count prevents deletion */
 132     } __cachealign;
 133     struct {
 134             struct lock nc_lock;
 135     } __cachealign;
 136 };
 137
 138 /*
 139  * Namecache handles include a mount reference allowing topologies
 140  * to be replicated with mount overlays (nullfs mounts).
 141  */
 142 struct nchandle {
 143     struct namecache *ncp;              /* ncp in underlying filesystem */
 144     struct mount *mount;                /* mount pt (possible overlay) */
 145 };
 146
 147 /*
 148  * Flags in namecache.nc_flag (u_short)
 149  */
 150 #define NCF_NOTX        0x0001  /* 'x' bit not set in user, group, or world */
 151 #define NCF_WHITEOUT    0x0002  /* negative entry corresponds to whiteout */
 152 #define NCF_UNRESOLVED  0x0004  /* invalid or unresolved entry */
 153 #define NCF_ISMOUNTPT   0x0008  /* someone may have mounted on us here */
 154 #define NCF_SF_NOCACHE  0x0010  /* track swapcache chflags from attr */
 155 #define NCF_UF_CACHE    0x0020
 156 #define NCF_SF_PNOCACHE 0x0040  /* track from parent */
 157 #define NCF_UF_PCACHE   0x0080
 158 #define NCF_ISSYMLINK   0x0100  /* represents a symlink */
 159 #define NCF_ISDIR       0x0200  /* represents a directory */
 160 #define NCF_DESTROYED   0x0400  /* name association is considered destroyed */
 161 #define NCF_DEFEREDZAP  0x0800  /* zap defered due to lock unavailability */
 162 #define NCF_WXOK        0x1000  /* world-searchable (nlookup shortcut) */
 163 #define NCF_DUMMY       0x2000  /* dummy ncp, iterations ignore it */
 164
 165 /*
 166  * cache_inval[_vp]() flags
 167  */
 168 #define CINV_DESTROY    0x0001  /* flag so cache_nlookup ignores the ncp */
 169 #define CINV_UNUSED02   0x0002
 170 #define CINV_CHILDREN   0x0004  /* recursively set children to unresolved */
 171
 172 #ifdef _KERNEL
 173
 174 struct componentname;
 175 struct nlcomponent;
 176 struct mount;
 177
 178 void    cache_clearmntcache(struct mount *mp);
 179 void    cache_lock(struct nchandle *nch);
 180 void    cache_lock_maybe_shared(struct nchandle *nch, int excl);
 181 void    cache_relock(struct nchandle *nch1, struct ucred *cred1,
 182                         struct nchandle *nch2, struct ucred *cred2);
 183 int     cache_lock_nonblock(struct nchandle *nch);
 184 void    cache_unlock(struct nchandle *nch);
 185 int     cache_lockstatus(struct nchandle *nch);
 186 void    cache_setvp(struct nchandle *nch, struct vnode *vp);
 187 void    cache_settimeout(struct nchandle *nch, int nticks);
 188 void    cache_setunresolved(struct nchandle *nch);
 189 void    cache_clrmountpt(struct nchandle *nch);
 190 struct nchandle cache_nlookup(struct nchandle *nch,
 191                         struct nlcomponent *nlc);
 192 struct nchandle cache_nlookup_nonblock(struct nchandle *nch,
 193                         struct nlcomponent *nlc);
 194 struct nchandle cache_nlookup_nonlocked(struct nchandle *nch,
 195                         struct nlcomponent *nlc);
 196 int     cache_nlookup_maybe_shared(struct nchandle *nch,
 197                         struct nlcomponent *nlc, int excl,
 198                         struct nchandle *nchres);
 199 void    cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp);
 200 struct mount *cache_findmount(struct nchandle *nch);
 201 void    cache_dropmount(struct mount *mp);
 202 void    cache_ismounting(struct mount *mp);
 203 void    cache_unmounting(struct mount *mp);
 204 int     cache_inval(struct nchandle *nch, int flags);
 205 int     cache_inval_vp(struct vnode *vp, int flags);
 206 int     cache_inval_vp_nonblock(struct vnode *vp);
 207 void    cache_inval_wxok(struct vnode *vp);
 208 void    vfs_cache_setroot(struct vnode *vp, struct nchandle *nch);
 209
 210 int     cache_resolve(struct nchandle *nch, struct ucred *cred);
 211 void    cache_purge(struct vnode *vp);
 212 void    cache_purgevfs (struct mount *mp);
 213 void    cache_hysteresis(int critpath);
 214 void    cache_get(struct nchandle *nch, struct nchandle *target);
 215 int     cache_get_nonblock(struct nchandle *nch, int elmno,
 216                         struct nchandle *target);
 217 void    cache_get_maybe_shared(struct nchandle *nch,
 218                         struct nchandle *target, int excl);
 219 struct nchandle *cache_hold(struct nchandle *nch);
 220 void    cache_copy(struct nchandle *nch, struct nchandle *target);
 221 void    cache_changemount(struct nchandle *nch, struct mount *mp);
 222 void    cache_put(struct nchandle *nch);
 223 void    cache_drop(struct nchandle *nch);
 224 void    cache_drop_and_cache(struct nchandle *nch, int elmno);
 225 void    cache_zero(struct nchandle *nch);
 226 void    cache_rename(struct nchandle *fnch, struct nchandle *tnch);
 227 void    cache_unlink(struct nchandle *nch);
 228 int     cache_isopen(struct nchandle *nch);
 229 int     cache_vget(struct nchandle *, struct ucred *, int, struct vnode **);
 230 int     cache_vref(struct nchandle *, struct ucred *, struct vnode **);
 231 int     cache_fromdvp(struct vnode *, struct ucred *, int, struct nchandle *);
 232 int     cache_fullpath(struct proc *, struct nchandle *, struct nchandle *,
 233                         char **, char **, int);
 234 void    vfscache_rollup_cpu(struct globaldata *gd);
 235 struct vnode *cache_dvpref(struct namecache *ncp);
 236
 237 #endif
 238
 239 #endif