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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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61 * $DragonFly: src/sys/sys/namecache.h,v 1.31 2008/05/09 17:52:18 dillon Exp $
64 #ifndef _SYS_NAMECACHE_H_
65 #define _SYS_NAMECACHE_H_
68 #include <sys/types.h>
71 #include <sys/queue.h>
73 #ifndef _SYS_SPINLOCK_H_
74 #include <sys/spinlock.h>
76 #ifndef _SYS_THREAD_H_
77 #include <sys/thread.h>
84 TAILQ_HEAD(namecache_list
, namecache
);
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
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.
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.
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.
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.
116 TAILQ_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 */
125 u_char nc_nlen
; /* The length of the name, 255 max */
127 char *nc_name
; /* Separately allocated seg name */
129 int nc_timeout
; /* compared against ticks, or 0 */
130 u_int nc_lockstatus
; /* namespace locking */
131 int nc_negcpu
; /* which ncneg list are we on? */
132 struct thread
*nc_locktd
; /* namespace locking */
133 u_int nc_namecache_gen
; /* mount generation (autoclear) */
134 u_int nc_generation
; /* rename/unlink generation */
138 * Namecache handles include a mount reference allowing topologies
139 * to be replicated with mount overlays (nullfs mounts).
142 struct namecache
*ncp
; /* ncp in underlying filesystem */
143 struct mount
*mount
; /* mount pt (possible overlay) */
147 * Flags in namecache.nc_flag (u_short)
149 #define NCF_UNUSED01 0x0001
150 #define NCF_WHITEOUT 0x0002 /* negative entry corresponds to whiteout */
151 #define NCF_UNRESOLVED 0x0004 /* invalid or unresolved entry */
152 #define NCF_ISMOUNTPT 0x0008 /* someone may have mounted on us here */
153 #define NCF_SF_NOCACHE 0x0010 /* track swapcache chflags from attr */
154 #define NCF_UF_CACHE 0x0020
155 #define NCF_SF_PNOCACHE 0x0040 /* track from parent */
156 #define NCF_UF_PCACHE 0x0080
157 #define NCF_ISSYMLINK 0x0100 /* represents a symlink */
158 #define NCF_ISDIR 0x0200 /* represents a directory */
159 #define NCF_DESTROYED 0x0400 /* name association is considered destroyed */
160 #define NCF_DEFEREDZAP 0x0800 /* zap defered due to lock unavailability */
161 #define NCF_WXOK 0x1000 /* world-searchable (nlookup shortcut) */
162 #define NCF_DUMMY 0x2000 /* dummy ncp, iterations ignore it */
164 #define NC_EXLOCK_REQ 0x80000000 /* nc_lockstatus state flag */
165 #define NC_SHLOCK_REQ 0x40000000 /* nc_lockstatus state flag */
166 #define NC_SHLOCK_FLAG 0x20000000 /* nc_lockstatus state flag */
167 #define NC_SHLOCK_VHOLD 0x10000000 /* nc_lockstatus state flag */
170 * cache_inval[_vp]() flags
172 #define CINV_DESTROY 0x0001 /* flag so cache_nlookup ignores the ncp */
173 #define CINV_UNUSED02 0x0002
174 #define CINV_CHILDREN 0x0004 /* recursively set children to unresolved */
178 struct componentname
;
182 void cache_clearmntcache(void);
183 void cache_lock(struct nchandle
*nch
);
184 void cache_lock_maybe_shared(struct nchandle
*nch
, int excl
);
185 void cache_relock(struct nchandle
*nch1
, struct ucred
*cred1
,
186 struct nchandle
*nch2
, struct ucred
*cred2
);
187 int cache_lock_nonblock(struct nchandle
*nch
);
188 void cache_unlock(struct nchandle
*nch
);
189 int cache_lockstatus(struct nchandle
*nch
);
190 void cache_setvp(struct nchandle
*nch
, struct vnode
*vp
);
191 void cache_settimeout(struct nchandle
*nch
, int nticks
);
192 void cache_setunresolved(struct nchandle
*nch
);
193 void cache_clrmountpt(struct nchandle
*nch
);
194 struct nchandle
cache_nlookup(struct nchandle
*nch
, struct nlcomponent
*nlc
);
195 struct nchandle
cache_nlookup_nonblock(struct nchandle
*nch
,
196 struct nlcomponent
*nlc
);
197 int cache_nlookup_maybe_shared(struct nchandle
*nch
,
198 struct nlcomponent
*nlc
, int excl
,
199 struct nchandle
*nchres
);
200 void cache_allocroot(struct nchandle
*nch
, struct mount
*mp
, struct vnode
*vp
);
201 struct mount
*cache_findmount(struct nchandle
*nch
);
202 void cache_dropmount(struct mount
*mp
);
203 void cache_ismounting(struct mount
*mp
);
204 void cache_unmounting(struct mount
*mp
);
205 int cache_inval(struct nchandle
*nch
, int flags
);
206 int cache_inval_vp(struct vnode
*vp
, int flags
);
207 int cache_inval_vp_nonblock(struct vnode
*vp
);
208 void cache_inval_wxok(struct vnode
*vp
);
209 void vfs_cache_setroot(struct vnode
*vp
, struct nchandle
*nch
);
211 int cache_resolve(struct nchandle
*nch
, struct ucred
*cred
);
212 void cache_purge(struct vnode
*vp
);
213 void cache_purgevfs (struct mount
*mp
);
214 void cache_hysteresis(int critpath
);
215 void cache_get(struct nchandle
*nch
, struct nchandle
*target
);
216 int cache_get_nonblock(struct nchandle
*nch
, 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_copy_ncdir(struct proc
*p
, struct nchandle
*target
);
222 void cache_changemount(struct nchandle
*nch
, struct mount
*mp
);
223 void cache_put(struct nchandle
*nch
);
224 void cache_drop(struct nchandle
*nch
);
225 void cache_drop_and_cache(struct nchandle
*nch
);
226 void cache_drop_ncdir(struct nchandle
*nch
);
227 void cache_zero(struct nchandle
*nch
);
228 void cache_rename(struct nchandle
*fnch
, struct nchandle
*tnch
);
229 void cache_unlink(struct nchandle
*nch
);
230 int cache_isopen(struct nchandle
*nch
);
231 int cache_vget(struct nchandle
*, struct ucred
*, int, struct vnode
**);
232 int cache_vref(struct nchandle
*, struct ucred
*, struct vnode
**);
233 int cache_fromdvp(struct vnode
*, struct ucred
*, int, struct nchandle
*);
234 int cache_fullpath(struct proc
*, struct nchandle
*, struct nchandle
*,
235 char **, char **, int);
236 void vfscache_rollup_cpu(struct globaldata
*gd
);