1 /* -*- linux-c -*- --------------------------------------------------------- *
3 * drivers/staging/autofs/dirhash.c
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
7 * This file is part of the Linux kernel and is made available under
8 * the terms of the GNU General Public License, version 2, or at your
9 * option, any later version, incorporated herein by reference.
11 * ------------------------------------------------------------------------- */
15 /* Functions for maintenance of expiry queue */
17 static void autofs_init_usage(struct autofs_dirhash
*dh
,
18 struct autofs_dir_ent
*ent
)
20 list_add_tail(&ent
->exp
, &dh
->expiry_head
);
21 ent
->last_usage
= jiffies
;
24 static void autofs_delete_usage(struct autofs_dir_ent
*ent
)
29 void autofs_update_usage(struct autofs_dirhash
*dh
,
30 struct autofs_dir_ent
*ent
)
32 autofs_delete_usage(ent
); /* Unlink from current position */
33 autofs_init_usage(dh
, ent
); /* Relink at queue tail */
36 struct autofs_dir_ent
*autofs_expire(struct super_block
*sb
,
37 struct autofs_sb_info
*sbi
,
40 struct autofs_dirhash
*dh
= &sbi
->dirhash
;
41 struct autofs_dir_ent
*ent
;
42 unsigned long timeout
= sbi
->exp_timeout
;
48 if (list_empty(&dh
->expiry_head
) || sbi
->catatonic
)
49 return NULL
; /* No entries */
50 /* We keep the list sorted by last_usage and want old stuff */
51 ent
= list_entry(dh
->expiry_head
.next
,
52 struct autofs_dir_ent
, exp
);
53 if (jiffies
- ent
->last_usage
< timeout
)
55 /* Move to end of list in case expiry isn't desirable */
56 autofs_update_usage(dh
, ent
);
58 /* Check to see that entry is expirable */
59 if (ent
->ino
< AUTOFS_FIRST_DIR_INO
)
60 return ent
; /* Symlinks are always expirable */
62 /* Get the dentry for the autofs subdirectory */
63 path
.dentry
= ent
->dentry
;
66 /* Should only happen in catatonic mode */
67 printk(KERN_DEBUG
"autofs: dentry == NULL but inode \
68 range is directory, entry %s\n", ent
->name
);
69 autofs_delete_usage(ent
);
73 if (!path
.dentry
->d_inode
) {
75 printk(KERN_DEBUG
"autofs: negative dentry on expiry queue: %s\n",
77 autofs_delete_usage(ent
);
81 /* Make sure entry is mounted and unused; note that dentry will
82 point to the mounted-on-top root. */
83 if (!S_ISDIR(path
.dentry
->d_inode
->i_mode
) ||
84 !d_mountpoint(path
.dentry
)) {
85 DPRINTK(("autofs: not expirable \
86 (not a mounted directory): %s\n", ent
->name
));
91 if (!follow_down_one(&path
)) {
93 DPRINTK(("autofs: not expirable\
94 (not a mounted directory): %s\n", ent
->name
));
97 follow_down(&path
, false); // TODO: need to check error
98 umount_ok
= may_umount(path
.mnt
);
102 DPRINTK(("autofs: signaling expire on %s\n",
104 return ent
; /* Expirable! */
107 DPRINTK(("autofs: didn't expire due to may_umount: %s\n",
110 return NULL
; /* No expirable entries */
113 void autofs_initialize_hash(struct autofs_dirhash
*dh
)
115 memset(&dh
->h
, 0, AUTOFS_HASH_SIZE
*sizeof(struct autofs_dir_ent
*));
116 INIT_LIST_HEAD(&dh
->expiry_head
);
119 struct autofs_dir_ent
*autofs_hash_lookup(const struct autofs_dirhash
*dh
,
122 struct autofs_dir_ent
*dhn
;
124 DPRINTK(("autofs_hash_lookup: hash = 0x%08x, name = ", name
->hash
));
125 autofs_say(name
->name
, name
->len
);
127 for (dhn
= dh
->h
[(unsigned) name
->hash
% AUTOFS_HASH_SIZE
];
130 if (name
->hash
== dhn
->hash
&&
131 name
->len
== dhn
->len
&&
132 !memcmp(name
->name
, dhn
->name
, name
->len
))
139 void autofs_hash_insert(struct autofs_dirhash
*dh
, struct autofs_dir_ent
*ent
)
141 struct autofs_dir_ent
**dhnp
;
143 DPRINTK(("autofs_hash_insert: hash = 0x%08x, name = ", ent
->hash
));
144 autofs_say(ent
->name
, ent
->len
);
146 autofs_init_usage(dh
, ent
);
150 dhnp
= &dh
->h
[(unsigned) ent
->hash
% AUTOFS_HASH_SIZE
];
155 ent
->next
->back
= &(ent
->next
);
158 void autofs_hash_delete(struct autofs_dir_ent
*ent
)
160 *(ent
->back
) = ent
->next
;
162 ent
->next
->back
= ent
->back
;
164 autofs_delete_usage(ent
);
173 * Used by readdir(). We must validate "ptr", so we can't simply make it
174 * a pointer. Values below 0xffff are reserved; calling with any value
175 * <= 0x10000 will return the first entry found.
177 * "last" can be NULL or the value returned by the last search *if* we
178 * want the next sequential entry.
180 struct autofs_dir_ent
*autofs_hash_enum(const struct autofs_dirhash
*dh
,
181 off_t
*ptr
, struct autofs_dir_ent
*last
)
183 int bucket
, ecount
, i
;
184 struct autofs_dir_ent
*ent
;
186 bucket
= (*ptr
>> 16) - 1;
187 ecount
= *ptr
& 0xffff;
192 DPRINTK(("autofs_hash_enum: bucket %d, entry %d\n", bucket
, ecount
));
194 ent
= last
? last
->next
: NULL
;
199 while (bucket
< AUTOFS_HASH_SIZE
) {
201 for (i
= ecount
; ent
&& i
; i
--)
205 ecount
++; /* Point to *next* entry */
209 bucket
++; ecount
= 0;
215 printk(KERN_DEBUG
"autofs_hash_enum: nothing found\n");
217 printk(KERN_DEBUG
"autofs_hash_enum: found hash %08x, name",
219 autofs_say(ent
->name
, ent
->len
);
223 *ptr
= ((bucket
+1) << 16) + ecount
;
227 /* Iterate over all the ents, and remove all dentry pointers. Used on
228 entering catatonic mode, in order to make the filesystem unmountable. */
229 void autofs_hash_dputall(struct autofs_dirhash
*dh
)
232 struct autofs_dir_ent
*ent
;
234 for (i
= 0 ; i
< AUTOFS_HASH_SIZE
; i
++) {
235 for (ent
= dh
->h
[i
] ; ent
; ent
= ent
->next
) {
244 /* Delete everything. This is used on filesystem destruction, so we
245 make no attempt to keep the pointers valid */
246 void autofs_hash_nuke(struct autofs_sb_info
*sbi
)
249 struct autofs_dir_ent
*ent
, *nent
;
251 for (i
= 0 ; i
< AUTOFS_HASH_SIZE
; i
++) {
252 for (ent
= sbi
->dirhash
.h
[i
] ; ent
; ent
= nent
) {
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