/* -*- linux-c -*- --------------------------------------------------------- *
*
* linux/fs/autofs/dirhash.c
*
* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
*
* This file is part of the Linux kernel and is made available under
* the terms of the GNU General Public License, version 2, or at your
* option, any later version, incorporated herein by reference.
*
* ------------------------------------------------------------------------- */
#include "autofs_i.h"
/* Functions for maintenance of expiry queue */
static void autofs_init_usage(struct autofs_dirhash *dh,
struct autofs_dir_ent *ent)
{
list_add_tail(&ent->exp, &dh->expiry_head);
ent->last_usage = jiffies;
}
static void autofs_delete_usage(struct autofs_dir_ent *ent)
{
list_del(&ent->exp);
}
void autofs_update_usage(struct autofs_dirhash *dh,
struct autofs_dir_ent *ent)
{
autofs_delete_usage(ent); /* Unlink from current position */
autofs_init_usage(dh,ent); /* Relink at queue tail */
}
struct autofs_dir_ent *autofs_expire(struct super_block *sb,
struct autofs_sb_info *sbi,
struct vfsmount *mnt)
{
struct autofs_dirhash *dh = &sbi->dirhash;
struct autofs_dir_ent *ent;
struct dentry *dentry;
unsigned long timeout = sbi->exp_timeout;
while (1) {
if ( list_empty(&dh->expiry_head) || sbi->catatonic )
return NULL; /* No entries */
/* We keep the list sorted by last_usage and want old stuff */
ent = list_entry(dh->expiry_head.next, struct autofs_dir_ent, exp);
if (jiffies - ent->last_usage < timeout)
break;
/* Move to end of list in case expiry isn't desirable */
autofs_update_usage(dh, ent);
/* Check to see that entry is expirable */
if ( ent->ino < AUTOFS_FIRST_DIR_INO )
return ent; /* Symlinks are always expirable */
/* Get the dentry for the autofs subdirectory */
dentry = ent->dentry;
if ( !dentry ) {
/* Should only happen in catatonic mode */
printk("autofs: dentry == NULL but inode range is directory, entry %s\n", ent->name);
autofs_delete_usage(ent);
continue;
}
if ( !dentry->d_inode ) {
dput(dentry);
printk("autofs: negative dentry on expiry queue: %s\n",
ent->name);
autofs_delete_usage(ent);
continue;
}
/* Make sure entry is mounted and unused; note that dentry will
point to the mounted-on-top root. */
if (!S_ISDIR(dentry->d_inode->i_mode)||!d_mountpoint(dentry)) {
DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
continue;
}
mntget(mnt);
dget(dentry);
if (!follow_down(&mnt, &dentry)) {
dput(dentry);
mntput(mnt);
DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
continue;
}
while (d_mountpoint(dentry) && follow_down(&mnt, &dentry))
;
dput(dentry);
if ( may_umount(mnt) == 0 ) {
mntput(mnt);
DPRINTK(("autofs: signaling expire on %s\n", ent->name));
return ent; /* Expirable! */
}
DPRINTK(("autofs: didn't expire due to may_umount: %s\n", ent->name));
mntput(mnt);
}
return NULL; /* No expirable entries */
}
void autofs_initialize_hash(struct autofs_dirhash *dh) {
memset(&dh->h, 0, AUTOFS_HASH_SIZE*sizeof(struct autofs_dir_ent *));
INIT_LIST_HEAD(&dh->expiry_head);
}
struct autofs_dir_ent *autofs_hash_lookup(const struct autofs_dirhash *dh, struct qstr *name)
{
struct autofs_dir_ent *dhn;
DPRINTK(("autofs_hash_lookup: hash = 0x%08x, name = ", name->hash));
autofs_say(name->name,name->len);
for ( dhn = dh->h[(unsigned) name->hash % AUTOFS_HASH_SIZE] ; dhn ; dhn = dhn->next ) {
if ( name->hash == dhn->hash &&
name->len == dhn->len &&
!memcmp(name->name, dhn->name, name->len) )
break;
}
return dhn;
}
void autofs_hash_insert(struct autofs_dirhash *dh, struct autofs_dir_ent *ent)
{
struct autofs_dir_ent **dhnp;
DPRINTK(("autofs_hash_insert: hash = 0x%08x, name = ", ent->hash));
autofs_say(ent->name,ent->len);
autofs_init_usage(dh,ent);
if (ent->dentry)
dget(ent->dentry);
dhnp = &dh->h[(unsigned) ent->hash % AUTOFS_HASH_SIZE];
ent->next = *dhnp;
ent->back = dhnp;
*dhnp = ent;
if ( ent->next )
ent->next->back = &(ent->next);
}
void autofs_hash_delete(struct autofs_dir_ent *ent)
{
*(ent->back) = ent->next;
if ( ent->next )
ent->next->back = ent->back;
autofs_delete_usage(ent);
if ( ent->dentry )
dput(ent->dentry);
kfree(ent->name);
kfree(ent);
}
/*
* Used by readdir(). We must validate "ptr", so we can't simply make it
* a pointer. Values below 0xffff are reserved; calling with any value
* <= 0x10000 will return the first entry found.
*
* "last" can be NULL or the value returned by the last search *if* we
* want the next sequential entry.
*/
struct autofs_dir_ent *autofs_hash_enum(const struct autofs_dirhash *dh,
off_t *ptr, struct autofs_dir_ent *last)
{
int bucket, ecount, i;
struct autofs_dir_ent *ent;
bucket = (*ptr >> 16) - 1;
ecount = *ptr & 0xffff;
if ( bucket < 0 ) {
bucket = ecount = 0;
}
DPRINTK(("autofs_hash_enum: bucket %d, entry %d\n", bucket, ecount));
ent = last ? last->next : NULL;
if ( ent ) {
ecount++;
} else {
while ( bucket < AUTOFS_HASH_SIZE ) {
ent = dh->h[bucket];
for ( i = ecount ; ent && i ; i-- )
ent = ent->next;
if (ent) {
ecount++; /* Point to *next* entry */
break;
}
bucket++; ecount = 0;
}
}
#ifdef DEBUG
if ( !ent )
printk("autofs_hash_enum: nothing found\n");
else {
printk("autofs_hash_enum: found hash %08x, name", ent->hash);
autofs_say(ent->name,ent->len);
}
#endif
*ptr = ((bucket+1) << 16) + ecount;
return ent;
}
/* Iterate over all the ents, and remove all dentry pointers. Used on
entering catatonic mode, in order to make the filesystem unmountable. */
void autofs_hash_dputall(struct autofs_dirhash *dh)
{
int i;
struct autofs_dir_ent *ent;
for ( i = 0 ; i < AUTOFS_HASH_SIZE ; i++ ) {
for ( ent = dh->h[i] ; ent ; ent = ent->next ) {
if ( ent->dentry ) {
dput(ent->dentry);
ent->dentry = NULL;
}
}
}
}
/* Delete everything. This is used on filesystem destruction, so we
make no attempt to keep the pointers valid */
void autofs_hash_nuke(struct autofs_dirhash *dh)
{
int i;
struct autofs_dir_ent *ent, *nent;
for ( i = 0 ; i < AUTOFS_HASH_SIZE ; i++ ) {
for ( ent = dh->h[i] ; ent ; ent = nent ) {
nent = ent->next;
if ( ent->dentry )
dput(ent->dentry);
kfree(ent->name);
kfree(ent);
}
}
}
