[mirror_ubuntu-jammy-kernel.git] / fs / afs / cell.c

/* AFS cell and server record management
 *
 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include "internal.h"

DECLARE_RWSEM(afs_proc_cells_sem);
LIST_HEAD(afs_proc_cells);

static struct list_head afs_cells = LIST_HEAD_INIT(afs_cells);
static DEFINE_RWLOCK(afs_cells_lock);
static DECLARE_RWSEM(afs_cells_sem); /* add/remove serialisation */
static DECLARE_WAIT_QUEUE_HEAD(afs_cells_freeable_wq);
static struct afs_cell *afs_cell_root;

/*
 * create a cell record
 * - "name" is the name of the cell
 * - "vllist" is a colon separated list of IP addresses in "a.b.c.d" format
 */
struct afs_cell *afs_cell_create(const char *name, char *vllist)
{
	struct afs_cell *cell;
	char *next;
	int ret;

	_enter("%s,%s", name, vllist);

	BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */

	/* allocate and initialise a cell record */
	cell = kmalloc(sizeof(struct afs_cell) + strlen(name) + 1, GFP_KERNEL);
	if (!cell) {
		_leave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
	}

	down_write(&afs_cells_sem);

	memset(cell, 0, sizeof(struct afs_cell));
	atomic_set(&cell->usage, 1);

	INIT_LIST_HEAD(&cell->link);

	rwlock_init(&cell->servers_lock);
	INIT_LIST_HEAD(&cell->servers);

	init_rwsem(&cell->vl_sem);
	INIT_LIST_HEAD(&cell->vl_list);
	spin_lock_init(&cell->vl_lock);

	strcpy(cell->name, name);

	/* fill in the VL server list from the rest of the string */
	ret = -EINVAL;
	do {
		unsigned a, b, c, d;

		next = strchr(vllist, ':');
		if (next)
			*next++ = 0;

		if (sscanf(vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
			goto badaddr;

		if (a > 255 || b > 255 || c > 255 || d > 255)
			goto badaddr;

		cell->vl_addrs[cell->vl_naddrs++].s_addr =
			htonl((a << 24) | (b << 16) | (c << 8) | d);

		if (cell->vl_naddrs >= AFS_CELL_MAX_ADDRS)
			break;

	} while ((vllist = next));

	/* add a proc directory for this cell */
	ret = afs_proc_cell_setup(cell);
	if (ret < 0)
		goto error;

#ifdef AFS_CACHING_SUPPORT
	/* put it up for caching */
	cachefs_acquire_cookie(afs_cache_netfs.primary_index,
			       &afs_vlocation_cache_index_def,
			       cell,
			       &cell->cache);
#endif

	/* add to the cell lists */
	write_lock(&afs_cells_lock);
	list_add_tail(&cell->link, &afs_cells);
	write_unlock(&afs_cells_lock);

	down_write(&afs_proc_cells_sem);
	list_add_tail(&cell->proc_link, &afs_proc_cells);
	up_write(&afs_proc_cells_sem);
	up_write(&afs_cells_sem);

	_leave(" = %p", cell);
	return cell;

badaddr:
	printk(KERN_ERR "kAFS: bad VL server IP address\n");
error:
	up_write(&afs_cells_sem);
	kfree(cell);
	_leave(" = %d", ret);
	return ERR_PTR(ret);
}

/*
 * set the root cell information
 * - can be called with a module parameter string
 * - can be called from a write to /proc/fs/afs/rootcell
 */
int afs_cell_init(char *rootcell)
{
	struct afs_cell *old_root, *new_root;
	char *cp;

	_enter("");

	if (!rootcell) {
		/* module is loaded with no parameters, or built statically.
		 * - in the future we might initialize cell DB here.
		 */
		_leave(" = 0 [no root]");
		return 0;
	}

	cp = strchr(rootcell, ':');
	if (!cp) {
		printk(KERN_ERR "kAFS: no VL server IP addresses specified\n");
		_leave(" = -EINVAL");
		return -EINVAL;
	}

	/* allocate a cell record for the root cell */
	*cp++ = 0;
	new_root = afs_cell_create(rootcell, cp);
	if (IS_ERR(new_root)) {
		_leave(" = %ld", PTR_ERR(new_root));
		return PTR_ERR(new_root);
	}

	/* install the new cell */
	write_lock(&afs_cells_lock);
	old_root = afs_cell_root;
	afs_cell_root = new_root;
	write_unlock(&afs_cells_lock);
	afs_put_cell(old_root);

	_leave(" = 0");
	return 0;
}

/*
 * lookup a cell record
 */
struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz)
{
	struct afs_cell *cell;

	_enter("\"%*.*s\",", namesz, namesz, name ? name : "");

	down_read(&afs_cells_sem);
	read_lock(&afs_cells_lock);

	if (name) {
		/* if the cell was named, look for it in the cell record list */
		list_for_each_entry(cell, &afs_cells, link) {
			if (strncmp(cell->name, name, namesz) == 0) {
				afs_get_cell(cell);
				goto found;
			}
		}
		cell = ERR_PTR(-ENOENT);
	found:
		;
	} else {
		cell = afs_cell_root;
		if (!cell) {
			/* this should not happen unless user tries to mount
			 * when root cell is not set. Return an impossibly
			 * bizzare errno to alert the user. Things like
			 * ENOENT might be "more appropriate" but they happen
			 * for other reasons.
			 */
			cell = ERR_PTR(-EDESTADDRREQ);
		} else {
			afs_get_cell(cell);
		}

	}

	read_unlock(&afs_cells_lock);
	up_read(&afs_cells_sem);
	_leave(" = %p", cell);
	return cell;
}

/*
 * try and get a cell record
 */
struct afs_cell *afs_get_cell_maybe(struct afs_cell *cell)
{
	write_lock(&afs_cells_lock);

	if (cell && !list_empty(&cell->link))
		afs_get_cell(cell);
	else
		cell = NULL;

	write_unlock(&afs_cells_lock);
	return cell;
}

/*
 * destroy a cell record
 */
void afs_put_cell(struct afs_cell *cell)
{
	if (!cell)
		return;

	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);

	ASSERTCMP(atomic_read(&cell->usage), >, 0);

	/* to prevent a race, the decrement and the dequeue must be effectively
	 * atomic */
	write_lock(&afs_cells_lock);

	if (likely(!atomic_dec_and_test(&cell->usage))) {
		write_unlock(&afs_cells_lock);
		_leave("");
		return;
	}

	ASSERT(list_empty(&cell->servers));
	ASSERT(list_empty(&cell->vl_list));

	write_unlock(&afs_cells_lock);

	wake_up(&afs_cells_freeable_wq);

	_leave(" [unused]");
}

/*
 * destroy a cell record
 * - must be called with the afs_cells_sem write-locked
 * - cell->link should have been broken by the caller
 */
static void afs_cell_destroy(struct afs_cell *cell)
{
	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);

	ASSERTCMP(atomic_read(&cell->usage), >=, 0);
	ASSERT(list_empty(&cell->link));

	/* wait for everyone to stop using the cell */
	if (atomic_read(&cell->usage) > 0) {
		DECLARE_WAITQUEUE(myself, current);

		_debug("wait for cell %s", cell->name);
		set_current_state(TASK_UNINTERRUPTIBLE);
		add_wait_queue(&afs_cells_freeable_wq, &myself);

		while (atomic_read(&cell->usage) > 0) {
			schedule();
			set_current_state(TASK_UNINTERRUPTIBLE);
		}

		remove_wait_queue(&afs_cells_freeable_wq, &myself);
		set_current_state(TASK_RUNNING);
	}

	_debug("cell dead");
	ASSERTCMP(atomic_read(&cell->usage), ==, 0);
	ASSERT(list_empty(&cell->servers));
	ASSERT(list_empty(&cell->vl_list));

	afs_proc_cell_remove(cell);

	down_write(&afs_proc_cells_sem);
	list_del_init(&cell->proc_link);
	up_write(&afs_proc_cells_sem);

#ifdef AFS_CACHING_SUPPORT
	cachefs_relinquish_cookie(cell->cache, 0);
#endif

	kfree(cell);

	_leave(" [destroyed]");
}

/*
 * purge in-memory cell database on module unload or afs_init() failure
 * - the timeout daemon is stopped before calling this
 */
void afs_cell_purge(void)
{
	struct afs_cell *cell;

	_enter("");

	afs_put_cell(afs_cell_root);

	down_write(&afs_cells_sem);

	while (!list_empty(&afs_cells)) {
		cell = NULL;

		/* remove the next cell from the front of the list */
		write_lock(&afs_cells_lock);

		if (!list_empty(&afs_cells)) {
			cell = list_entry(afs_cells.next,
					  struct afs_cell, link);
			list_del_init(&cell->link);
		}

		write_unlock(&afs_cells_lock);

		if (cell) {
			_debug("PURGING CELL %s (%d)",
			       cell->name, atomic_read(&cell->usage));

			/* now the cell should be left with no references */
			afs_cell_destroy(cell);
		}
	}

	up_write(&afs_cells_sem);
	_leave("");
}
Commit	Line	Data
ec26815a	1	/* AFS cell and server record management
1da177e4 LT	2	*
	3	* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/module.h>
1da177e4	13	#include <linux/slab.h>
1da177e4 LT	14	#include "internal.h"
	15
	16	DECLARE_RWSEM(afs_proc_cells_sem);
	17	LIST_HEAD(afs_proc_cells);
	18
	19	static struct list_head afs_cells = LIST_HEAD_INIT(afs_cells);
	20	static DEFINE_RWLOCK(afs_cells_lock);
	21	static DECLARE_RWSEM(afs_cells_sem); /* add/remove serialisation */
08e0e7c8	22	static DECLARE_WAIT_QUEUE_HEAD(afs_cells_freeable_wq);
1da177e4 LT	23	static struct afs_cell *afs_cell_root;
1da177e4 LT	24
1da177e4 LT	25	/*
	26	* create a cell record
	27	* - "name" is the name of the cell
	28	* - "vllist" is a colon separated list of IP addresses in "a.b.c.d" format
	29	*/
08e0e7c8	30	struct afs_cell afs_cell_create(const char name, char *vllist)
1da177e4 LT	31	{
	32	struct afs_cell *cell;
	33	char *next;
	34	int ret;
	35
08e0e7c8	36	_enter("%s,%s", name, vllist);
1da177e4 LT	37
	38	BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */
	39
	40	/* allocate and initialise a cell record */
	41	cell = kmalloc(sizeof(struct afs_cell) + strlen(name) + 1, GFP_KERNEL);
	42	if (!cell) {
	43	_leave(" = -ENOMEM");
08e0e7c8	44	return ERR_PTR(-ENOMEM);
1da177e4 LT	45	}
	46
	47	down_write(&afs_cells_sem);
	48
	49	memset(cell, 0, sizeof(struct afs_cell));
08e0e7c8	50	atomic_set(&cell->usage, 1);
1da177e4 LT	51
	52	INIT_LIST_HEAD(&cell->link);
	53
08e0e7c8 DH	54	rwlock_init(&cell->servers_lock);
08e0e7c8 DH	55	INIT_LIST_HEAD(&cell->servers);
1da177e4 LT	56
	57	init_rwsem(&cell->vl_sem);
	58	INIT_LIST_HEAD(&cell->vl_list);
08e0e7c8	59	spin_lock_init(&cell->vl_lock);
1da177e4	60
08e0e7c8	61	strcpy(cell->name, name);
1da177e4 LT	62
	63	/* fill in the VL server list from the rest of the string */
	64	ret = -EINVAL;
	65	do {
	66	unsigned a, b, c, d;
	67
	68	next = strchr(vllist, ':');
	69	if (next)
	70	*next++ = 0;
	71
	72	if (sscanf(vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
	73	goto badaddr;
	74
	75	if (a > 255 \|\| b > 255 \|\| c > 255 \|\| d > 255)
	76	goto badaddr;
	77
	78	cell->vl_addrs[cell->vl_naddrs++].s_addr =
	79	htonl((a << 24) \| (b << 16) \| (c << 8) \| d);
	80
	81	if (cell->vl_naddrs >= AFS_CELL_MAX_ADDRS)
	82	break;
	83
08e0e7c8	84	} while ((vllist = next));
1da177e4	85
08e0e7c8	86	/* add a proc directory for this cell */
1da177e4 LT	87	ret = afs_proc_cell_setup(cell);
	88	if (ret < 0)
	89	goto error;
	90
	91	#ifdef AFS_CACHING_SUPPORT
	92	/* put it up for caching */
	93	cachefs_acquire_cookie(afs_cache_netfs.primary_index,
	94	&afs_vlocation_cache_index_def,
	95	cell,
	96	&cell->cache);
	97	#endif
	98
	99	/* add to the cell lists */
	100	write_lock(&afs_cells_lock);
	101	list_add_tail(&cell->link, &afs_cells);
	102	write_unlock(&afs_cells_lock);
	103
	104	down_write(&afs_proc_cells_sem);
	105	list_add_tail(&cell->proc_link, &afs_proc_cells);
	106	up_write(&afs_proc_cells_sem);
1da177e4 LT	107	up_write(&afs_cells_sem);
1da177e4 LT	108
08e0e7c8 DH	109	_leave(" = %p", cell);
08e0e7c8 DH	110	return cell;
1da177e4	111
ec26815a	112	badaddr:
08e0e7c8	113	printk(KERN_ERR "kAFS: bad VL server IP address\n");
ec26815a	114	error:
1da177e4 LT	115	up_write(&afs_cells_sem);
	116	kfree(cell);
	117	_leave(" = %d", ret);
08e0e7c8	118	return ERR_PTR(ret);
ec26815a	119	}
1da177e4	120
1da177e4	121	/*
08e0e7c8 DH	122	* set the root cell information
	123	* - can be called with a module parameter string
	124	* - can be called from a write to /proc/fs/afs/rootcell
1da177e4 LT	125	*/
	126	int afs_cell_init(char *rootcell)
	127	{
	128	struct afs_cell old_root, new_root;
	129	char *cp;
1da177e4 LT	130
	131	_enter("");
	132
	133	if (!rootcell) {
	134	/* module is loaded with no parameters, or built statically.
	135	* - in the future we might initialize cell DB here.
	136	*/
08e0e7c8	137	_leave(" = 0 [no root]");
1da177e4 LT	138	return 0;
	139	}
	140
	141	cp = strchr(rootcell, ':');
	142	if (!cp) {
	143	printk(KERN_ERR "kAFS: no VL server IP addresses specified\n");
08e0e7c8	144	_leave(" = -EINVAL");
1da177e4 LT	145	return -EINVAL;
	146	}
	147
	148	/* allocate a cell record for the root cell */
	149	*cp++ = 0;
08e0e7c8 DH	150	new_root = afs_cell_create(rootcell, cp);
	151	if (IS_ERR(new_root)) {
	152	_leave(" = %ld", PTR_ERR(new_root));
	153	return PTR_ERR(new_root);
1da177e4 LT	154	}
1da177e4 LT	155
08e0e7c8	156	/* install the new cell */
1da177e4	157	write_lock(&afs_cells_lock);
08e0e7c8	158	old_root = afs_cell_root;
1da177e4 LT	159	afs_cell_root = new_root;
1da177e4 LT	160	write_unlock(&afs_cells_lock);
08e0e7c8	161	afs_put_cell(old_root);
1da177e4	162
08e0e7c8 DH	163	_leave(" = 0");
08e0e7c8 DH	164	return 0;
ec26815a	165	}
1da177e4	166
1da177e4 LT	167	/*
	168	* lookup a cell record
	169	*/
08e0e7c8	170	struct afs_cell afs_cell_lookup(const char name, unsigned namesz)
1da177e4 LT	171	{
1da177e4 LT	172	struct afs_cell *cell;
1da177e4 LT	173
	174	_enter("\"%.s\",", namesz, namesz, name ? name : "");
	175
08e0e7c8 DH	176	down_read(&afs_cells_sem);
08e0e7c8 DH	177	read_lock(&afs_cells_lock);
1da177e4 LT	178
	179	if (name) {
	180	/* if the cell was named, look for it in the cell record list */
1da177e4 LT	181	list_for_each_entry(cell, &afs_cells, link) {
	182	if (strncmp(cell->name, name, namesz) == 0) {
	183	afs_get_cell(cell);
	184	goto found;
	185	}
	186	}
08e0e7c8	187	cell = ERR_PTR(-ENOENT);
1da177e4	188	found:
08e0e7c8	189	;
ec26815a	190	} else {
1da177e4 LT	191	cell = afs_cell_root;
	192	if (!cell) {
	193	/* this should not happen unless user tries to mount
	194	* when root cell is not set. Return an impossibly
	195	* bizzare errno to alert the user. Things like
	196	* ENOENT might be "more appropriate" but they happen
	197	* for other reasons.
	198	*/
08e0e7c8	199	cell = ERR_PTR(-EDESTADDRREQ);
ec26815a	200	} else {
1da177e4	201	afs_get_cell(cell);
1da177e4 LT	202	}
1da177e4 LT	203
1da177e4 LT	204	}
1da177e4 LT	205
08e0e7c8 DH	206	read_unlock(&afs_cells_lock);
	207	up_read(&afs_cells_sem);
	208	_leave(" = %p", cell);
	209	return cell;
ec26815a	210	}
1da177e4	211
1da177e4 LT	212	/*
	213	* try and get a cell record
	214	*/
08e0e7c8	215	struct afs_cell afs_get_cell_maybe(struct afs_cell cell)
1da177e4	216	{
1da177e4 LT	217	write_lock(&afs_cells_lock);
1da177e4 LT	218
1da177e4 LT	219	if (cell && !list_empty(&cell->link))
	220	afs_get_cell(cell);
	221	else
	222	cell = NULL;
	223
	224	write_unlock(&afs_cells_lock);
1da177e4	225	return cell;
ec26815a	226	}
1da177e4	227
1da177e4 LT	228	/*
	229	* destroy a cell record
	230	*/
	231	void afs_put_cell(struct afs_cell *cell)
	232	{
	233	if (!cell)
	234	return;
	235
	236	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
	237
08e0e7c8	238	ASSERTCMP(atomic_read(&cell->usage), >, 0);
1da177e4 LT	239
	240	/* to prevent a race, the decrement and the dequeue must be effectively
	241	* atomic */
	242	write_lock(&afs_cells_lock);
	243
	244	if (likely(!atomic_dec_and_test(&cell->usage))) {
	245	write_unlock(&afs_cells_lock);
	246	_leave("");
	247	return;
	248	}
	249
08e0e7c8 DH	250	ASSERT(list_empty(&cell->servers));
	251	ASSERT(list_empty(&cell->vl_list));
	252
1da177e4 LT	253	write_unlock(&afs_cells_lock);
1da177e4 LT	254
08e0e7c8	255	wake_up(&afs_cells_freeable_wq);
1da177e4 LT	256
1da177e4 LT	257	_leave(" [unused]");
ec26815a	258	}
1da177e4	259
1da177e4 LT	260	/*
1da177e4 LT	261	* destroy a cell record
08e0e7c8 DH	262	* - must be called with the afs_cells_sem write-locked
08e0e7c8 DH	263	* - cell->link should have been broken by the caller
1da177e4 LT	264	*/
	265	static void afs_cell_destroy(struct afs_cell *cell)
	266	{
	267	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
	268
08e0e7c8 DH	269	ASSERTCMP(atomic_read(&cell->usage), >=, 0);
08e0e7c8 DH	270	ASSERT(list_empty(&cell->link));
1da177e4	271
08e0e7c8 DH	272	/* wait for everyone to stop using the cell */
	273	if (atomic_read(&cell->usage) > 0) {
	274	DECLARE_WAITQUEUE(myself, current);
1da177e4	275
08e0e7c8 DH	276	_debug("wait for cell %s", cell->name);
	277	set_current_state(TASK_UNINTERRUPTIBLE);
	278	add_wait_queue(&afs_cells_freeable_wq, &myself);
1da177e4	279
08e0e7c8 DH	280	while (atomic_read(&cell->usage) > 0) {
	281	schedule();
	282	set_current_state(TASK_UNINTERRUPTIBLE);
	283	}
1da177e4	284
08e0e7c8 DH	285	remove_wait_queue(&afs_cells_freeable_wq, &myself);
	286	set_current_state(TASK_RUNNING);
	287	}
	288
	289	_debug("cell dead");
	290	ASSERTCMP(atomic_read(&cell->usage), ==, 0);
	291	ASSERT(list_empty(&cell->servers));
	292	ASSERT(list_empty(&cell->vl_list));
1da177e4 LT	293
	294	afs_proc_cell_remove(cell);
	295
	296	down_write(&afs_proc_cells_sem);
	297	list_del_init(&cell->proc_link);
	298	up_write(&afs_proc_cells_sem);
	299
	300	#ifdef AFS_CACHING_SUPPORT
	301	cachefs_relinquish_cookie(cell->cache, 0);
	302	#endif
	303
1da177e4 LT	304	kfree(cell);
	305
	306	_leave(" [destroyed]");
ec26815a	307	}
1da177e4	308
1da177e4 LT	309	/*
	310	* purge in-memory cell database on module unload or afs_init() failure
	311	* - the timeout daemon is stopped before calling this
	312	*/
	313	void afs_cell_purge(void)
	314	{
1da177e4 LT	315	struct afs_cell *cell;
	316
	317	_enter("");
	318
	319	afs_put_cell(afs_cell_root);
	320
08e0e7c8 DH	321	down_write(&afs_cells_sem);
08e0e7c8 DH	322
1da177e4 LT	323	while (!list_empty(&afs_cells)) {
	324	cell = NULL;
	325
	326	/* remove the next cell from the front of the list */
	327	write_lock(&afs_cells_lock);
	328
	329	if (!list_empty(&afs_cells)) {
	330	cell = list_entry(afs_cells.next,
	331	struct afs_cell, link);
	332	list_del_init(&cell->link);
	333	}
	334
	335	write_unlock(&afs_cells_lock);
	336
	337	if (cell) {
	338	_debug("PURGING CELL %s (%d)",
	339	cell->name, atomic_read(&cell->usage));
	340
1da177e4 LT	341	/* now the cell should be left with no references */
	342	afs_cell_destroy(cell);
	343	}
	344	}
	345
08e0e7c8	346	up_write(&afs_cells_sem);
1da177e4	347	_leave("");
ec26815a	348	}