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 1.16 2004/11/18 20:04:26 dillon Exp $
68 #ifndef _SYS_NAMECACHE_H_
69 #define _SYS_NAMECACHE_H_
73 TAILQ_HEAD(namecache_list, namecache);
76 * The namecache structure is used to manage the filesystem namespace. Most
77 * vnodes cached by the system will reference one or more associated namecache
80 * The namecache is disjoint, there may not always be a path to the system
81 * root through nc_parent links. If a namecache entry has no parent, that
82 * entry will not be hashed and can only be 'found' via '.' or '..'.
84 * Because the namecache structure maintains the path through mount points,
85 * null, and union mounts, and other VFS overlays, several namecache
86 * structures may pass through the same vnode. Also note that namespaces
87 * relating to non-existant (i.e. not-yet-created) files/directories may be
88 * locked. Lock coherency is achieved by requiring that the particular
89 * namecache record whos parent represents the physical directory in which
90 * the namespace operation is to occur be the one that is locked. In
91 * overlay cases, the (union, nullfs) VFS, or in namei when crossing a mount
92 * point, may have to obtain multiple namespace record locks to avoid
93 * confusion, but only the one representing the physical directory is passed
94 * into lower layer VOP calls.
96 * Many new API VOP operations do not pass vnodes. In these cases the
97 * operations vector is typically obtained via nc_mount->mnt_vn_ops.
100 LIST_ENTRY(namecache) nc_hash; /* hash chain (nc_parent,name) */
101 TAILQ_ENTRY(namecache) nc_entry; /* scan via nc_parent->nc_list */
102 TAILQ_ENTRY(namecache) nc_vnode; /* scan via vnode->v_namecache */
103 struct namecache_list nc_list; /* list of children */
104 struct namecache *nc_parent; /* namecache entry for parent */
105 struct vnode *nc_vp; /* vnode representing name or NULL */
106 int nc_refs; /* ref count prevents deletion */
108 u_char nc_nlen; /* The length of the name, 255 max */
110 char *nc_name; /* Separately allocated seg name */
112 int nc_timeout; /* compared against ticks, or 0 */
113 int nc_exlocks; /* namespace locking */
114 struct thread *nc_locktd; /* namespace locking */
115 struct mount *nc_mount; /* associated mount for vopops */
118 typedef struct namecache *namecache_t;
121 * Flags in namecache.nc_flag (u_char)
123 #define NCF_LOCKED 0x0001 /* locked namespace */
124 #define NCF_WHITEOUT 0x0002 /* negative entry corresponds to whiteout */
125 #define NCF_UNRESOLVED 0x0004 /* invalid or unresolved entry */
126 #define NCF_MOUNTPT 0x0008 /* mount point */
127 #define NCF_ROOT 0x0010 /* namecache root (static) */
128 #define NCF_HASHED 0x0020 /* namecache entry in hash table */
129 #define NCF_LOCKREQ 0x0040
130 #define NCF_UNUSED080 0x0080
131 #define NCF_ISSYMLINK 0x0100 /* represents a symlink */
132 #define NCF_ISDIR 0x0200 /* represents a directory */
133 #define NCF_DESTROYED 0x0400 /* name association is considered destroyed */
136 * cache_inval[_vp]() flags
138 #define CINV_DESTROY 0x0001 /* flag so cache_nlookup ignores the ncp */
139 #define CINV_UNUSED02 0x0002
140 #define CINV_CHILDREN 0x0004 /* recursively set children to unresolved */
144 struct vop_lookup_args;
145 struct componentname;
149 void cache_lock(struct namecache *ncp);
150 int cache_lock_nonblock(struct namecache *ncp);
151 void cache_unlock(struct namecache *ncp);
152 void cache_setvp(struct namecache *ncp, struct vnode *vp);
153 void cache_settimeout(struct namecache *ncp, int nticks);
154 void cache_setunresolved(struct namecache *ncp);
155 struct namecache *cache_nlookup(struct namecache *par, struct nlcomponent *nlc);
156 struct namecache *cache_allocroot(struct mount *mp, struct vnode *vp);
157 void cache_inval(struct namecache *ncp, int flags);
158 void cache_inval_vp(struct vnode *vp, int flags);
159 void vfs_cache_setroot(struct vnode *vp, struct namecache *ncp);
161 int cache_resolve(struct namecache *ncp, struct ucred *cred);
162 void cache_purge(struct vnode *vp);
163 void cache_purgevfs (struct mount *mp);
164 int cache_get_nonblock(struct namecache *ncp);
165 void cache_cleanneg(int count);
166 struct namecache *cache_get(struct namecache *ncp);
167 struct namecache *cache_hold(struct namecache *ncp);
168 void cache_put(struct namecache *ncp);
169 void cache_drop(struct namecache *ncp);
170 void cache_rename(struct namecache *fncp, struct namecache *tncp);
171 int cache_vget(struct namecache *, struct ucred *, int, struct vnode **);
172 int cache_vref(struct namecache *, struct ucred *, struct vnode **);
173 struct namecache *cache_fromdvp(struct vnode *, struct ucred *, int);