[linux.git] / fs / autofs / dirhash.c

/* -*- 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;
	unsigned long timeout = sbi->exp_timeout;

	while (1) {
		struct path path;
		int umount_ok;

		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 */
		path.dentry = ent->dentry;

		if (!path.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 (!path.dentry->d_inode) {
			dput(path.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(path.dentry->d_inode->i_mode) ||
		    !d_mountpoint(path.dentry)) {
			DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
			continue;
		}
		path.mnt = mnt;
		path_get(&path);
		if (!follow_down(&path)) {
			path_put(&path);
			DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
			continue;
		}
		while (d_mountpoint(path.dentry) && follow_down(&path))
			;
		umount_ok = may_umount(path.mnt);
		path_put(&path);

		if (umount_ok) {
			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));
	}
	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_sb_info *sbi)
{
	int i;
	struct autofs_dir_ent *ent, *nent;

	for ( i = 0 ; i < AUTOFS_HASH_SIZE ; i++ ) {
		for ( ent = sbi->dirhash.h[i] ; ent ; ent = nent ) {
			nent = ent->next;
			if ( ent->dentry )
				dput(ent->dentry);
			kfree(ent->name);
			kfree(ent);
		}
	}
}
Commit	Line	Data
1da177e4 LT	1	/* -- linux-c -- --------------------------------------------------------- *
	2	*
	3	* linux/fs/autofs/dirhash.c
	4	*
	5	* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
	6	*
	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.
	10	*
	11	* ------------------------------------------------------------------------- */
	12
	13	#include "autofs_i.h"
	14
	15	/* Functions for maintenance of expiry queue */
	16
	17	static void autofs_init_usage(struct autofs_dirhash *dh,
	18	struct autofs_dir_ent *ent)
	19	{
	20	list_add_tail(&ent->exp, &dh->expiry_head);
	21	ent->last_usage = jiffies;
	22	}
	23
	24	static void autofs_delete_usage(struct autofs_dir_ent *ent)
	25	{
	26	list_del(&ent->exp);
	27	}
	28
	29	void autofs_update_usage(struct autofs_dirhash *dh,
	30	struct autofs_dir_ent *ent)
	31	{
	32	autofs_delete_usage(ent); /* Unlink from current position */
	33	autofs_init_usage(dh,ent); /* Relink at queue tail */
	34	}
	35
	36	struct autofs_dir_ent autofs_expire(struct super_block sb,
	37	struct autofs_sb_info *sbi,
	38	struct vfsmount *mnt)
	39	{
	40	struct autofs_dirhash *dh = &sbi->dirhash;
	41	struct autofs_dir_ent *ent;
1da177e4 LT	42	unsigned long timeout = sbi->exp_timeout;
	43
	44	while (1) {
117aff74 AV	45	struct path path;
	46	int umount_ok;
	47
1da177e4 LT	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, struct autofs_dir_ent, exp);
	52	if (jiffies - ent->last_usage < timeout)
	53	break;
	54	/* Move to end of list in case expiry isn't desirable */
	55	autofs_update_usage(dh, ent);
	56
	57	/* Check to see that entry is expirable */
	58	if ( ent->ino < AUTOFS_FIRST_DIR_INO )
	59	return ent; /* Symlinks are always expirable */
	60
	61	/* Get the dentry for the autofs subdirectory */
117aff74	62	path.dentry = ent->dentry;
1da177e4	63
117aff74	64	if (!path.dentry) {
1da177e4 LT	65	/* Should only happen in catatonic mode */
	66	printk("autofs: dentry == NULL but inode range is directory, entry %s\n", ent->name);
	67	autofs_delete_usage(ent);
	68	continue;
	69	}
	70
117aff74 AV	71	if (!path.dentry->d_inode) {
117aff74 AV	72	dput(path.dentry);
1da177e4 LT	73	printk("autofs: negative dentry on expiry queue: %s\n",
	74	ent->name);
	75	autofs_delete_usage(ent);
	76	continue;
	77	}
	78
	79	/* Make sure entry is mounted and unused; note that dentry will
	80	point to the mounted-on-top root. */
117aff74 AV	81	if (!S_ISDIR(path.dentry->d_inode->i_mode) \|\|
117aff74 AV	82	!d_mountpoint(path.dentry)) {
1da177e4 LT	83	DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
	84	continue;
	85	}
117aff74 AV	86	path.mnt = mnt;
117aff74 AV	87	path_get(&path);
9393bd07	88	if (!follow_down(&path)) {
117aff74	89	path_put(&path);
1da177e4 LT	90	DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
	91	continue;
	92	}
a419aef8	93	while (d_mountpoint(path.dentry) && follow_down(&path))
1da177e4	94	;
117aff74 AV	95	umount_ok = may_umount(path.mnt);
117aff74 AV	96	path_put(&path);
1da177e4	97
117aff74	98	if (umount_ok) {
1da177e4 LT	99	DPRINTK(("autofs: signaling expire on %s\n", ent->name));
	100	return ent; /* Expirable! */
	101	}
	102	DPRINTK(("autofs: didn't expire due to may_umount: %s\n", ent->name));
1da177e4 LT	103	}
	104	return NULL; /* No expirable entries */
	105	}
	106
	107	void autofs_initialize_hash(struct autofs_dirhash *dh) {
	108	memset(&dh->h, 0, AUTOFS_HASH_SIZEsizeof(struct autofs_dir_ent ));
	109	INIT_LIST_HEAD(&dh->expiry_head);
	110	}
	111
	112	struct autofs_dir_ent autofs_hash_lookup(const struct autofs_dirhash dh, struct qstr *name)
	113	{
	114	struct autofs_dir_ent *dhn;
	115
	116	DPRINTK(("autofs_hash_lookup: hash = 0x%08x, name = ", name->hash));
	117	autofs_say(name->name,name->len);
	118
	119	for ( dhn = dh->h[(unsigned) name->hash % AUTOFS_HASH_SIZE] ; dhn ; dhn = dhn->next ) {
	120	if ( name->hash == dhn->hash &&
	121	name->len == dhn->len &&
	122	!memcmp(name->name, dhn->name, name->len) )
	123	break;
	124	}
	125
	126	return dhn;
	127	}
	128
	129	void autofs_hash_insert(struct autofs_dirhash dh, struct autofs_dir_ent ent)
	130	{
	131	struct autofs_dir_ent **dhnp;
	132
	133	DPRINTK(("autofs_hash_insert: hash = 0x%08x, name = ", ent->hash));
	134	autofs_say(ent->name,ent->len);
	135
	136	autofs_init_usage(dh,ent);
	137	if (ent->dentry)
	138	dget(ent->dentry);
	139
	140	dhnp = &dh->h[(unsigned) ent->hash % AUTOFS_HASH_SIZE];
	141	ent->next = *dhnp;
	142	ent->back = dhnp;
	143	*dhnp = ent;
	144	if ( ent->next )
	145	ent->next->back = &(ent->next);
	146	}
	147
	148	void autofs_hash_delete(struct autofs_dir_ent *ent)
	149	{
	150	*(ent->back) = ent->next;
	151	if ( ent->next )
	152	ent->next->back = ent->back;
	153
	154	autofs_delete_usage(ent);
	155
	156	if ( ent->dentry )
	157	dput(ent->dentry);
	158	kfree(ent->name);
	159	kfree(ent);
	160	}
	161
	162	/*
	163	* Used by readdir(). We must validate "ptr", so we can't simply make it
	164	* a pointer. Values below 0xffff are reserved; calling with any value
	165	* <= 0x10000 will return the first entry found.
	166	*
167	* "last" can be NULL or the value returned by the last search if we
168	* want the next sequential entry.
169	*/
170	struct autofs_dir_ent autofs_hash_enum(const struct autofs_dirhash dh,
171	off_t ptr, struct autofs_dir_ent last)
172	{
173	int bucket, ecount, i;
174	struct autofs_dir_ent *ent;
175
176	bucket = (*ptr >> 16) - 1;
177	ecount = *ptr & 0xffff;
178
179	if ( bucket < 0 ) {
180	bucket = ecount = 0;
181	}
182
183	DPRINTK(("autofs_hash_enum: bucket %d, entry %d\n", bucket, ecount));
184
185	ent = last ? last->next : NULL;
186
187	if ( ent ) {
188	ecount++;
189	} else {
190	while ( bucket < AUTOFS_HASH_SIZE ) {
191	ent = dh->h[bucket];
192	for ( i = ecount ; ent && i ; i-- )
193	ent = ent->next;
194
195	if (ent) {
196	ecount++; /* Point to next entry */
197	break;
198	}
199
200	bucket++; ecount = 0;
201	}
202	}
203
204	#ifdef DEBUG
205	if ( !ent )
206	printk("autofs_hash_enum: nothing found\n");
207	else {
208	printk("autofs_hash_enum: found hash %08x, name", ent->hash);
209	autofs_say(ent->name,ent->len);
210	}
211	#endif
212
213	*ptr = ((bucket+1) << 16) + ecount;
214	return ent;
215	}
216
217	/* Iterate over all the ents, and remove all dentry pointers. Used on
218	entering catatonic mode, in order to make the filesystem unmountable. */
219	void autofs_hash_dputall(struct autofs_dirhash *dh)
220	{
221	int i;
222	struct autofs_dir_ent *ent;
223
224	for ( i = 0 ; i < AUTOFS_HASH_SIZE ; i++ ) {
225	for ( ent = dh->h[i] ; ent ; ent = ent->next ) {
226	if ( ent->dentry ) {
227	dput(ent->dentry);
228	ent->dentry = NULL;
229	}
230	}
231	}
232	}
233
234	/* Delete everything. This is used on filesystem destruction, so we
235	make no attempt to keep the pointers valid */
f76baf93	236	void autofs_hash_nuke(struct autofs_sb_info *sbi)
1da177e4 LT	237	{
	238	int i;
	239	struct autofs_dir_ent ent, nent;
	240
	241	for ( i = 0 ; i < AUTOFS_HASH_SIZE ; i++ ) {
f76baf93	242	for ( ent = sbi->dirhash.h[i] ; ent ; ent = nent ) {
1da177e4 LT	243	nent = ent->next;
	244	if ( ent->dentry )
	245	dput(ent->dentry);
	246	kfree(ent->name);
	247	kfree(ent);
	248	}
	249	}
	250	}