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4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
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62 #ifndef _SYS_NAMECACHE_H_
63 #define _SYS_NAMECACHE_H_
66 #include <sys/types.h>
72 #include <sys/queue.h>
74 #ifndef _SYS_SPINLOCK_H_
75 #include <sys/spinlock.h>
82 TAILQ_HEAD(namecache_list, namecache);
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
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.
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.
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.
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.
114 * This is naturally 1, plus 1 more if resolved (either positively
115 * or negatively), plus 1 ref for each child in ncp->nc_list, plus
116 * thread-held and mountcache refs.
119 * This is adjusted by 2 whenever a locked ncp's resolve state,
120 * destroyed state, name/association, or link state changes, and
121 * then adjusted by 2 again when the operation is complete. Thus,
122 * if (nc_generation & 2) != 0 or (nc_generation & ~1) has changed,
123 * an unlocked accessor should cycle a lock and retry.
126 TAILQ_ENTRY(namecache) nc_hash; /* hash chain (nc_parent,name) */
127 TAILQ_ENTRY(namecache) nc_entry; /* scan via nc_parent->nc_list */
128 TAILQ_ENTRY(namecache) nc_vnode; /* scan via vnode->v_namecache */
129 struct namecache_list nc_list; /* list of children */
130 struct nchash_head *nc_head;
131 struct namecache *nc_parent; /* namecache entry for parent */
132 struct vnode *nc_vp; /* vnode representing name or NULL */
134 u_char nc_nlen; /* The length of the name, 255 max */
136 char *nc_name; /* Separately allocated seg name */
138 int nc_timeout; /* compared against ticks, or 0 */
139 int nc_negcpu; /* which ncneg list are we on? */
141 u_int nc_namecache_gen; /* mount generation (autoclear) */
142 u_int nc_generation; /* see notes above */
143 int nc_refs; /* ref count prevents deletion */
151 * Namecache handles include a mount reference allowing topologies
152 * to be replicated with mount overlays (nullfs mounts).
155 struct namecache *ncp; /* ncp in underlying filesystem */
156 struct mount *mount; /* mount pt (possible overlay) */
160 * Flags in namecache.nc_flag (u_short)
162 #define NCF_NOTX 0x0001 /* 'x' bit not set in user, group, or world */
163 #define NCF_WHITEOUT 0x0002 /* negative entry corresponds to whiteout */
164 #define NCF_UNRESOLVED 0x0004 /* invalid or unresolved entry */
165 #define NCF_ISMOUNTPT 0x0008 /* someone may have mounted on us here */
166 #define NCF_SF_NOCACHE 0x0010 /* track swapcache chflags from attr */
167 #define NCF_UF_CACHE 0x0020
168 #define NCF_SF_PNOCACHE 0x0040 /* track from parent */
169 #define NCF_UF_PCACHE 0x0080
170 #define NCF_ISSYMLINK 0x0100 /* represents a symlink */
171 #define NCF_ISDIR 0x0200 /* represents a directory */
172 #define NCF_DESTROYED 0x0400 /* name association is considered destroyed */
173 #define NCF_DEFEREDZAP 0x0800 /* zap defered due to lock unavailability */
174 #define NCF_WXOK 0x1000 /* world-searchable (nlookup shortcut) */
175 #define NCF_DUMMY 0x2000 /* dummy ncp, iterations ignore it */
178 * cache_inval[_vp]() flags
180 #define CINV_DESTROY 0x0001 /* flag so cache_nlookup ignores the ncp */
181 #define CINV_UNUSED02 0x0002
182 #define CINV_CHILDREN 0x0004 /* recursively set children to unresolved */
186 struct componentname;
190 void cache_clearmntcache(struct mount *mp);
191 void cache_lock(struct nchandle *nch);
192 void cache_lock_maybe_shared(struct nchandle *nch, int excl);
193 void cache_lock4_tondlocked(
194 struct nchandle *fncpd, struct nchandle *fncp,
195 struct nchandle *tncpd, struct nchandle *tncp,
196 struct ucred *fcred, struct ucred *tcred);
197 int cache_lock_nonblock(struct nchandle *nch);
198 void cache_unlock(struct nchandle *nch);
199 int cache_lockstatus(struct nchandle *nch);
200 void cache_setvp(struct nchandle *nch, struct vnode *vp);
201 void cache_settimeout(struct nchandle *nch, int nticks);
202 void cache_setunresolved(struct nchandle *nch);
203 void cache_clrmountpt(struct nchandle *nch);
204 struct nchandle cache_nlookup(struct nchandle *nch,
205 struct nlcomponent *nlc);
206 struct nchandle cache_nlookup_nonblock(struct nchandle *nch,
207 struct nlcomponent *nlc);
208 struct nchandle cache_nlookup_nonlocked(struct nchandle *nch,
209 struct nlcomponent *nlc);
210 int cache_nlookup_maybe_shared(struct nchandle *nch,
211 struct nlcomponent *nlc, int excl,
212 struct nchandle *nchres);
213 void cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp);
214 struct mount *cache_findmount(struct nchandle *nch);
215 void cache_dropmount(struct mount *mp);
216 void cache_ismounting(struct mount *mp);
217 void cache_unmounting(struct mount *mp);
218 int cache_inval(struct nchandle *nch, int flags);
219 int cache_inval_vp(struct vnode *vp, int flags);
220 int cache_inval_vp_nonblock(struct vnode *vp);
221 void cache_inval_vp_quick(struct vnode *vp);
222 void cache_inval_wxok(struct vnode *vp);
223 void vfs_cache_setroot(struct vnode *vp, struct nchandle *nch);
225 int cache_resolve(struct nchandle *nch, u_int *genp, struct ucred *cred);
226 int cache_resolve_dvp(struct nchandle *nch, struct ucred *cred,
227 struct vnode **dvpp);
228 void cache_purge(struct vnode *vp);
229 void cache_purgevfs (struct mount *mp);
230 void cache_hysteresis(int critpath);
231 void cache_get(struct nchandle *nch, struct nchandle *target);
232 int cache_get_nonblock(struct nchandle *nch, int elmno,
233 struct nchandle *target);
234 void cache_get_maybe_shared(struct nchandle *nch,
235 struct nchandle *target, int excl);
236 struct nchandle *cache_hold(struct nchandle *nch);
237 void cache_copy(struct nchandle *nch, struct nchandle *target);
238 void cache_changemount(struct nchandle *nch, struct mount *mp);
239 void cache_put(struct nchandle *nch);
240 void cache_drop(struct nchandle *nch);
241 void cache_drop_and_cache(struct nchandle *nch, int elmno);
242 void cache_zero(struct nchandle *nch);
243 void cache_rename(struct nchandle *fnch, struct nchandle *tnch);
244 void cache_unlink(struct nchandle *nch);
245 int cache_isopen(struct nchandle *nch);
246 int cache_vget(struct nchandle *, struct ucred *, int, struct vnode **);
247 int cache_vref(struct nchandle *, struct ucred *, struct vnode **);
248 int cache_fromdvp(struct vnode *, struct ucred *, int, struct nchandle *);
249 int cache_fullpath(struct proc *, struct nchandle *, struct nchandle *,
250 char **, char **, int);
251 void vfscache_rollup_cpu(struct globaldata *gd);
252 struct vnode *cache_dvpref(struct namecache *ncp);