2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
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65 * $DragonFly: src/sys/sys/namecache.h,v 1.31 2008/05/09 17:52:18 dillon Exp $
68 #ifndef _SYS_NAMECACHE_H_
69 #define _SYS_NAMECACHE_H_
72 #include <sys/types.h>
75 #include <sys/queue.h>
77 #ifndef _SYS_SPINLOCK_H_
78 #include <sys/spinlock.h>
80 #ifndef _SYS_THREAD_H_
81 #include <sys/thread.h>
88 TAILQ_HEAD(namecache_list, namecache);
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
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.
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.
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.
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.
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 */
129 u_char nc_nlen; /* The length of the name, 255 max */
131 char *nc_name; /* Separately allocated seg name */
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 */
140 * Namecache handles include a mount reference allowing topologies
141 * to be replicated with mount overlays (nullfs mounts).
144 struct namecache *ncp; /* ncp in underlying filesystem */
145 struct mount *mount; /* mount pt (possible overlay) */
148 #define ASSERT_NCH_LOCKED(nch) KKASSERT(nch->ncp->nc_locktd == curthread)
151 * Flags in namecache.nc_flag (u_char)
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_SF_NOCACHE 0x0010 /* track swapcache chflags from attr */
158 #define NCF_UF_CACHE 0x0020
159 #define NCF_SF_PNOCACHE 0x0040 /* track from parent */
160 #define NCF_UF_PCACHE 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 */
166 #define NC_EXLOCK_REQ 0x80000000 /* ex_lock state */
169 * cache_inval[_vp]() flags
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 */
177 struct componentname;
181 void cache_lock(struct nchandle *nch);
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 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, struct nlcomponent *nlc);
191 struct nchandle cache_nlookup_nonblock(struct nchandle *nch,
192 struct nlcomponent *nlc);
193 void cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp);
194 struct mount *cache_findmount(struct nchandle *nch);
195 void cache_dropmount(struct mount *mp);
196 int cache_inval(struct nchandle *nch, int flags);
197 int cache_inval_vp(struct vnode *vp, int flags);
198 int cache_inval_vp_nonblock(struct vnode *vp);
199 void vfs_cache_setroot(struct vnode *vp, struct nchandle *nch);
201 int cache_resolve(struct nchandle *nch, struct ucred *cred);
202 void cache_purge(struct vnode *vp);
203 void cache_purgevfs (struct mount *mp);
204 int cache_get_nonblock(struct nchandle *nch, struct nchandle *target);
205 void cache_hysteresis(void);
206 void cache_get(struct nchandle *nch, struct nchandle *target);
207 struct nchandle *cache_hold(struct nchandle *nch);
208 void cache_copy(struct nchandle *nch, struct nchandle *target);
209 void cache_changemount(struct nchandle *nch, struct mount *mp);
210 void cache_put(struct nchandle *nch);
211 void cache_drop(struct nchandle *nch);
212 void cache_zero(struct nchandle *nch);
213 void cache_rename(struct nchandle *fnch, struct nchandle *tnch);
214 void cache_unlink(struct nchandle *nch);
215 int cache_vget(struct nchandle *, struct ucred *, int, struct vnode **);
216 int cache_vref(struct nchandle *, struct ucred *, struct vnode **);
217 int cache_fromdvp(struct vnode *, struct ucred *, int, struct nchandle *);
218 int cache_fullpath(struct proc *, struct nchandle *, struct nchandle *,
219 char **, char **, int);