FreeBSD/Linux Kernel Cross Reference
sys/sys/namecache.h

     /*
      * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
      * 
      * This code is derived from software contributed to The DragonFly Project
      * by Matthew Dillon <dillon@backplane.com>
      * 
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in
     *    the documentation and/or other materials provided with the
     *    distribution.
     * 3. Neither the name of The DragonFly Project nor the names of its
     *    contributors may be used to endorse or promote products derived
     *    from this software without specific, prior written permission.
     * 
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
     * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
     * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     * 
     * Copyright (c) 1989, 1993
     *      The Regents of the University of California.  All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $DragonFly: src/sys/sys/namecache.h,v 1.31 2008/05/09 17:52:18 dillon Exp $
     */
    
    #ifndef _SYS_NAMECACHE_H_
    #define _SYS_NAMECACHE_H_
    
    #ifndef _SYS_TYPES_H_
    #include <sys/types.h>
    #endif
    #ifndef _SYS_QUEUE_H_
    #include <sys/queue.h>
    #endif
    #ifndef _SYS_SPINLOCK_H_
    #include <sys/spinlock.h>
    #endif
    #ifndef _SYS_THREAD_H_
    #include <sys/thread.h>
    #endif
    
    struct vnode;
    struct ucred;
    struct proc;
    
    TAILQ_HEAD(namecache_list, namecache);
    
    /*
     * The namecache structure is used to manage the filesystem namespace.  Most
     * vnodes cached by the system will reference one or more associated namecache
     * structures.
     *
     * The DragonFly namecache maintains elements from active nodes to the root
     * in all but the NFS server case and the removed file/directory case.
     * NFS servers use fhtovp() and may have to regenerate the topology to
     * the leaf on the fly.
     *
    * Because the namecache structure maintains the path through mount points,
    * null, and union mounts, and other VFS overlays, several namecache
    * structures may pass through the same vnode.  Also note that namespaces
    * relating to non-existant (i.e. not-yet-created) files/directories may be
    * locked.  Lock coherency is achieved by requiring that the particular
    * namecache record whos parent represents the physical directory in which
    * the namespace operation is to occur be the one that is locked.  In 
    * overlay cases, the (union, nullfs) VFS, or in namei when crossing a mount
    * point, may have to obtain multiple namespace record locks to avoid
    * confusion, but only the one representing the physical directory is passed
    * into lower layer VOP calls.
    *
    * ncp locking is done using atomic ops on nc_lockstatus, including a request
    * flag for waiters.  nc_locktd is set after locking or cleared before
    * the last unlock.  ncp locks are reentrant.
    *
    * Many new API VOP operations do not pass vnodes.  In these cases the
    * operations vector is typically obtained via nc_mount->mnt_vn_use_ops.
    */
   struct namecache {
       LIST_ENTRY(namecache) nc_hash;      /* hash chain (nc_parent,name) */
       TAILQ_ENTRY(namecache) nc_entry;    /* scan via nc_parent->nc_list */
       TAILQ_ENTRY(namecache) nc_vnode;    /* scan via vnode->v_namecache */
       struct namecache_list  nc_list;     /* list of children */
       struct nchash_head  *nc_head;
       struct namecache    *nc_parent;     /* namecache entry for parent */
       struct vnode        *nc_vp;         /* vnode representing name or NULL */
       int                 nc_refs;        /* ref count prevents deletion */
       u_short             nc_flag;
       u_char              nc_nlen;        /* The length of the name, 255 max */
       u_char              nc_unused;
       char                *nc_name;       /* Separately allocated seg name */
       int                 nc_error;
       int                 nc_timeout;     /* compared against ticks, or 0 */
       u_int               nc_lockstatus;  /* namespace locking */
       struct thread       *nc_locktd;     /* namespace locking */
       long                nc_namecache_gen; /* cmp against mnt_namecache_gen */
   };
   
   /*
    * Namecache handles include a mount reference allowing topologies
    * to be replicated with mount overlays (nullfs mounts).
    */
   struct nchandle {
       struct namecache *ncp;              /* ncp in underlying filesystem */
       struct mount *mount;                /* mount pt (possible overlay) */
   };
   
   /*
    * Flags in namecache.nc_flag (u_char)
    */
   #define NCF_UNUSED01    0x0001
   #define NCF_WHITEOUT    0x0002  /* negative entry corresponds to whiteout */
   #define NCF_UNRESOLVED  0x0004  /* invalid or unresolved entry */
   #define NCF_ISMOUNTPT   0x0008  /* someone may have mounted on us here */
   #define NCF_SF_NOCACHE  0x0010  /* track swapcache chflags from attr */
   #define NCF_UF_CACHE    0x0020
   #define NCF_SF_PNOCACHE 0x0040  /* track from parent */
   #define NCF_UF_PCACHE   0x0080
   #define NCF_ISSYMLINK   0x0100  /* represents a symlink */
   #define NCF_ISDIR       0x0200  /* represents a directory */
   #define NCF_DESTROYED   0x0400  /* name association is considered destroyed */
   #define NCF_DEFEREDZAP  0x0800  /* zap defered due to lock unavailability */
   
   #define NC_EXLOCK_REQ   0x80000000      /* nc_lockstatus state flag */
   #define NC_SHLOCK_REQ   0x40000000      /* nc_lockstatus state flag */
   #define NC_SHLOCK_FLAG  0x20000000      /* nc_lockstatus state flag */
   #define NC_SHLOCK_VHOLD 0x10000000      /* nc_lockstatus state flag */
   
   /*
    * cache_inval[_vp]() flags
    */
   #define CINV_DESTROY    0x0001  /* flag so cache_nlookup ignores the ncp */
   #define CINV_UNUSED02   0x0002
   #define CINV_CHILDREN   0x0004  /* recursively set children to unresolved */
   
   #ifdef _KERNEL
   
   struct componentname;
   struct nlcomponent;
   struct mount;
   
   void    cache_lock(struct nchandle *nch);
   void    cache_lock_maybe_shared(struct nchandle *nch, int excl);
   void    cache_relock(struct nchandle *nch1, struct ucred *cred1,
                           struct nchandle *nch2, struct ucred *cred2);
   int     cache_lock_nonblock(struct nchandle *nch);
   void    cache_unlock(struct nchandle *nch);
   int     cache_lockstatus(struct nchandle *nch);
   void    cache_setvp(struct nchandle *nch, struct vnode *vp);
   void    cache_settimeout(struct nchandle *nch, int nticks);
   void    cache_setunresolved(struct nchandle *nch);
   void    cache_clrmountpt(struct nchandle *nch);
   struct nchandle cache_nlookup(struct nchandle *nch, struct nlcomponent *nlc);
   struct nchandle cache_nlookup_nonblock(struct nchandle *nch,
                           struct nlcomponent *nlc);
   int     cache_nlookup_maybe_shared(struct nchandle *nch,
                           struct nlcomponent *nlc, int excl,
                           struct nchandle *nchres);
   void    cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp);
   struct mount *cache_findmount(struct nchandle *nch);
   void    cache_dropmount(struct mount *mp);
   void    cache_ismounting(struct mount *mp);
   void    cache_unmounting(struct mount *mp);
   int     cache_inval(struct nchandle *nch, int flags);
   int     cache_inval_vp(struct vnode *vp, int flags);
   int     cache_inval_vp_nonblock(struct vnode *vp);
   void    vfs_cache_setroot(struct vnode *vp, struct nchandle *nch);
   
   int     cache_resolve(struct nchandle *nch, struct ucred *cred);
   void    cache_purge(struct vnode *vp);
   void    cache_purgevfs (struct mount *mp);
   void    cache_hysteresis(int critpath);
   void    cache_get(struct nchandle *nch, struct nchandle *target);
   int     cache_get_nonblock(struct nchandle *nch, struct nchandle *target);
   void    cache_get_maybe_shared(struct nchandle *nch,
                           struct nchandle *target, int excl);
   struct nchandle *cache_hold(struct nchandle *nch);
   void    cache_copy(struct nchandle *nch, struct nchandle *target);
   void    cache_changemount(struct nchandle *nch, struct mount *mp);
   void    cache_put(struct nchandle *nch);
   void    cache_drop(struct nchandle *nch);
   void    cache_zero(struct nchandle *nch);
   void    cache_rename(struct nchandle *fnch, struct nchandle *tnch);
   void    cache_unlink(struct nchandle *nch);
   int     cache_vget(struct nchandle *, struct ucred *, int, struct vnode **);
   int     cache_vref(struct nchandle *, struct ucred *, struct vnode **);
   int     cache_fromdvp(struct vnode *, struct ucred *, int, struct nchandle *);
   int     cache_fullpath(struct proc *, struct nchandle *, struct nchandle *,
                           char **, char **, int);
   
   #endif
   
   #endif

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