1 /* -*- c -*- --------------------------------------------------------------- *
3 * linux/fs/autofs/expire.c
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6 * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
8 * This file is part of the Linux kernel and is made available under
9 * the terms of the GNU General Public License, version 2, or at your
10 * option, any later version, incorporated herein by reference.
12 * ------------------------------------------------------------------------- */
15 #include <linux/mount.h>
18 * Determine if a subtree of the namespace is busy.
20 * mnt is the mount tree under the autofs mountpoint
22 static inline int is_vfsmnt_tree_busy(struct vfsmount *mnt)
24 struct vfsmount *this_parent = mnt;
25 struct list_head *next;
28 count = atomic_read(&mnt->mnt_count) - 1;
31 next = this_parent->mnt_mounts.next;
32 DPRINTK(("is_vfsmnt_tree_busy: mnt=%p, this_parent=%p, next=%p\n",
33 mnt, this_parent, next));
35 for( ; next != &this_parent->mnt_mounts; next = next->next) {
36 struct vfsmount *p = list_entry(next, struct vfsmount,
39 /* -1 for struct vfs_mount's normal count,
40 -1 to compensate for child's reference to parent */
41 count += atomic_read(&p->mnt_count) - 1 - 1;
43 DPRINTK(("is_vfsmnt_tree_busy: p=%p, count now %d\n",
46 if (!list_empty(&p->mnt_mounts)) {
50 /* root is busy if any leaf is busy */
51 if (atomic_read(&p->mnt_count) > 1)
55 /* All done at this level ... ascend and resume the search. */
56 if (this_parent != mnt) {
57 next = this_parent->mnt_child.next;
58 this_parent = this_parent->mnt_parent;
62 DPRINTK(("is_vfsmnt_tree_busy: count=%d\n", count));
63 return count != 0; /* remaining users? */
66 /* Traverse a dentry's list of vfsmounts and return the number of
68 static int check_vfsmnt(struct vfsmount *mnt, struct dentry *dentry)
70 int ret = dentry->d_mounted;
71 struct vfsmount *vfs = lookup_mnt(mnt, dentry);
75 if (is_vfsmnt_tree_busy(vfs))
78 DPRINTK(("check_vfsmnt: ret=%d\n", ret));
82 /* Check dentry tree for busyness. If a dentry appears to be busy
83 because it is a mountpoint, check to see if the mounted
84 filesystem is busy. */
85 static int is_tree_busy(struct vfsmount *topmnt, struct dentry *top)
87 struct dentry *this_parent;
88 struct list_head *next;
91 count = atomic_read(&top->d_count);
93 DPRINTK(("is_tree_busy: top=%p initial count=%d\n",
97 if (is_autofs4_dentry(top)) {
99 DPRINTK(("is_tree_busy: autofs; count=%d\n", count));
102 if (d_mountpoint(top))
103 count -= check_vfsmnt(topmnt, top);
106 next = this_parent->d_subdirs.next;
108 while (next != &this_parent->d_subdirs) {
110 struct dentry *dentry = list_entry(next, struct dentry,
114 count += atomic_read(&dentry->d_count) - 1;
116 if (d_mountpoint(dentry))
117 adj += check_vfsmnt(topmnt, dentry);
119 if (is_autofs4_dentry(dentry)) {
121 DPRINTK(("is_tree_busy: autofs; adj=%d\n",
127 if (!list_empty(&dentry->d_subdirs)) {
128 this_parent = dentry;
132 if (atomic_read(&dentry->d_count) != adj) {
133 DPRINTK(("is_tree_busy: busy leaf (d_count=%d adj=%d)\n",
134 atomic_read(&dentry->d_count), adj));
139 /* All done at this level ... ascend and resume the search. */
140 if (this_parent != top) {
141 next = this_parent->d_child.next;
142 this_parent = this_parent->d_parent;
146 DPRINTK(("is_tree_busy: count=%d\n", count));
147 return count != 0; /* remaining users? */
151 * Find an eligible tree to time-out
152 * A tree is eligible if :-
153 * - it is unused by any user process
154 * - it has been unused for exp_timeout time
156 static struct dentry *autofs4_expire(struct super_block *sb,
157 struct vfsmount *mnt,
158 struct autofs_sb_info *sbi,
161 unsigned long now = jiffies;
162 unsigned long timeout;
163 struct dentry *root = sb->s_root;
164 struct list_head *tmp;
166 if (!sbi->exp_timeout || !root)
169 timeout = sbi->exp_timeout;
171 spin_lock(&dcache_lock);
172 for(tmp = root->d_subdirs.next;
173 tmp != &root->d_subdirs;
175 struct autofs_info *ino;
176 struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
178 if (dentry->d_inode == NULL)
181 ino = autofs4_dentry_ino(dentry);
184 /* dentry in the process of being deleted */
188 /* No point expiring a pending mount */
189 if (dentry->d_flags & DCACHE_AUTOFS_PENDING)
193 /* Too young to die */
194 if (time_after(ino->last_used + timeout, now))
197 /* update last_used here :-
198 - obviously makes sense if it is in use now
199 - less obviously, prevents rapid-fire expire
200 attempts if expire fails the first time */
201 ino->last_used = now;
203 if (!is_tree_busy(mnt, dentry)) {
204 DPRINTK(("autofs_expire: returning %p %.*s\n",
205 dentry, (int)dentry->d_name.len, dentry->d_name.name));
206 /* Start from here next time */
207 list_del(&root->d_subdirs);
208 list_add(&root->d_subdirs, &dentry->d_child);
210 spin_unlock(&dcache_lock);
215 spin_unlock(&dcache_lock);
220 /* Perform an expiry operation */
221 int autofs4_expire_run(struct super_block *sb,
222 struct vfsmount *mnt,
223 struct autofs_sb_info *sbi,
224 struct autofs_packet_expire *pkt_p)
226 struct autofs_packet_expire pkt;
227 struct dentry *dentry;
229 memset(&pkt,0,sizeof pkt);
231 pkt.hdr.proto_version = sbi->version;
232 pkt.hdr.type = autofs_ptype_expire;
234 if ((dentry = autofs4_expire(sb, mnt, sbi, 0)) == NULL)
237 pkt.len = dentry->d_name.len;
238 memcpy(pkt.name, dentry->d_name.name, pkt.len);
239 pkt.name[pkt.len] = '\0';
242 if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
248 /* Call repeatedly until it returns -EAGAIN, meaning there's nothing
250 int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt,
251 struct autofs_sb_info *sbi, int *arg)
253 struct dentry *dentry;
257 if (arg && get_user(do_now, arg))
260 if ((dentry = autofs4_expire(sb, mnt, sbi, do_now)) != NULL) {
261 struct autofs_info *de_info = autofs4_dentry_ino(dentry);
263 /* This is synchronous because it makes the daemon a
265 de_info->flags |= AUTOFS_INF_EXPIRING;
266 ret = autofs4_wait(sbi, &dentry->d_name, NFY_EXPIRE);
267 de_info->flags &= ~AUTOFS_INF_EXPIRING;