cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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dm-log-userspace-base.c (22514B)


      1/*
      2 * Copyright (C) 2006-2009 Red Hat, Inc.
      3 *
      4 * This file is released under the LGPL.
      5 */
      6
      7#include <linux/bio.h>
      8#include <linux/slab.h>
      9#include <linux/jiffies.h>
     10#include <linux/dm-dirty-log.h>
     11#include <linux/device-mapper.h>
     12#include <linux/dm-log-userspace.h>
     13#include <linux/module.h>
     14#include <linux/workqueue.h>
     15
     16#include "dm-log-userspace-transfer.h"
     17
     18#define DM_LOG_USERSPACE_VSN "1.3.0"
     19
     20#define FLUSH_ENTRY_POOL_SIZE 16
     21
     22struct dm_dirty_log_flush_entry {
     23	int type;
     24	region_t region;
     25	struct list_head list;
     26};
     27
     28/*
     29 * This limit on the number of mark and clear request is, to a degree,
     30 * arbitrary.  However, there is some basis for the choice in the limits
     31 * imposed on the size of data payload by dm-log-userspace-transfer.c:
     32 * dm_consult_userspace().
     33 */
     34#define MAX_FLUSH_GROUP_COUNT 32
     35
     36struct log_c {
     37	struct dm_target *ti;
     38	struct dm_dev *log_dev;
     39
     40	char *usr_argv_str;
     41	uint32_t usr_argc;
     42
     43	uint32_t region_size;
     44	region_t region_count;
     45	uint64_t luid;
     46	char uuid[DM_UUID_LEN];
     47
     48	/*
     49	 * Mark and clear requests are held until a flush is issued
     50	 * so that we can group, and thereby limit, the amount of
     51	 * network traffic between kernel and userspace.  The 'flush_lock'
     52	 * is used to protect these lists.
     53	 */
     54	spinlock_t flush_lock;
     55	struct list_head mark_list;
     56	struct list_head clear_list;
     57
     58	/*
     59	 * in_sync_hint gets set when doing is_remote_recovering.  It
     60	 * represents the first region that needs recovery.  IOW, the
     61	 * first zero bit of sync_bits.  This can be useful for to limit
     62	 * traffic for calls like is_remote_recovering and get_resync_work,
     63	 * but be take care in its use for anything else.
     64	 */
     65	uint64_t in_sync_hint;
     66
     67	/*
     68	 * Workqueue for flush of clear region requests.
     69	 */
     70	struct workqueue_struct *dmlog_wq;
     71	struct delayed_work flush_log_work;
     72	atomic_t sched_flush;
     73
     74	/*
     75	 * Combine userspace flush and mark requests for efficiency.
     76	 */
     77	uint32_t integrated_flush;
     78
     79	mempool_t flush_entry_pool;
     80};
     81
     82static struct kmem_cache *_flush_entry_cache;
     83
     84static int userspace_do_request(struct log_c *lc, const char *uuid,
     85				int request_type, char *data, size_t data_size,
     86				char *rdata, size_t *rdata_size)
     87{
     88	int r;
     89
     90	/*
     91	 * If the server isn't there, -ESRCH is returned,
     92	 * and we must keep trying until the server is
     93	 * restored.
     94	 */
     95retry:
     96	r = dm_consult_userspace(uuid, lc->luid, request_type, data,
     97				 data_size, rdata, rdata_size);
     98
     99	if (r != -ESRCH)
    100		return r;
    101
    102	DMERR(" Userspace log server not found.");
    103	while (1) {
    104		set_current_state(TASK_INTERRUPTIBLE);
    105		schedule_timeout(2*HZ);
    106		DMWARN("Attempting to contact userspace log server...");
    107		r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_CTR,
    108					 lc->usr_argv_str,
    109					 strlen(lc->usr_argv_str) + 1,
    110					 NULL, NULL);
    111		if (!r)
    112			break;
    113	}
    114	DMINFO("Reconnected to userspace log server... DM_ULOG_CTR complete");
    115	r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_RESUME, NULL,
    116				 0, NULL, NULL);
    117	if (!r)
    118		goto retry;
    119
    120	DMERR("Error trying to resume userspace log: %d", r);
    121
    122	return -ESRCH;
    123}
    124
    125static int build_constructor_string(struct dm_target *ti,
    126				    unsigned argc, char **argv,
    127				    char **ctr_str)
    128{
    129	int i, str_size;
    130	char *str = NULL;
    131
    132	*ctr_str = NULL;
    133
    134	/*
    135	 * Determine overall size of the string.
    136	 */
    137	for (i = 0, str_size = 0; i < argc; i++)
    138		str_size += strlen(argv[i]) + 1; /* +1 for space between args */
    139
    140	str_size += 20; /* Max number of chars in a printed u64 number */
    141
    142	str = kzalloc(str_size, GFP_KERNEL);
    143	if (!str) {
    144		DMWARN("Unable to allocate memory for constructor string");
    145		return -ENOMEM;
    146	}
    147
    148	str_size = sprintf(str, "%llu", (unsigned long long)ti->len);
    149	for (i = 0; i < argc; i++)
    150		str_size += sprintf(str + str_size, " %s", argv[i]);
    151
    152	*ctr_str = str;
    153	return str_size;
    154}
    155
    156static void do_flush(struct work_struct *work)
    157{
    158	int r;
    159	struct log_c *lc = container_of(work, struct log_c, flush_log_work.work);
    160
    161	atomic_set(&lc->sched_flush, 0);
    162
    163	r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH, NULL, 0, NULL, NULL);
    164
    165	if (r)
    166		dm_table_event(lc->ti->table);
    167}
    168
    169/*
    170 * userspace_ctr
    171 *
    172 * argv contains:
    173 *	<UUID> [integrated_flush] <other args>
    174 * Where 'other args' are the userspace implementation-specific log
    175 * arguments.
    176 *
    177 * Example:
    178 *	<UUID> [integrated_flush] clustered-disk <arg count> <log dev>
    179 *	<region_size> [[no]sync]
    180 *
    181 * This module strips off the <UUID> and uses it for identification
    182 * purposes when communicating with userspace about a log.
    183 *
    184 * If integrated_flush is defined, the kernel combines flush
    185 * and mark requests.
    186 *
    187 * The rest of the line, beginning with 'clustered-disk', is passed
    188 * to the userspace ctr function.
    189 */
    190static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
    191			 unsigned argc, char **argv)
    192{
    193	int r = 0;
    194	int str_size;
    195	char *ctr_str = NULL;
    196	struct log_c *lc = NULL;
    197	uint64_t rdata;
    198	size_t rdata_size = sizeof(rdata);
    199	char *devices_rdata = NULL;
    200	size_t devices_rdata_size = DM_NAME_LEN;
    201
    202	if (argc < 3) {
    203		DMWARN("Too few arguments to userspace dirty log");
    204		return -EINVAL;
    205	}
    206
    207	lc = kzalloc(sizeof(*lc), GFP_KERNEL);
    208	if (!lc) {
    209		DMWARN("Unable to allocate userspace log context.");
    210		return -ENOMEM;
    211	}
    212
    213	/* The ptr value is sufficient for local unique id */
    214	lc->luid = (unsigned long)lc;
    215
    216	lc->ti = ti;
    217
    218	if (strlen(argv[0]) > (DM_UUID_LEN - 1)) {
    219		DMWARN("UUID argument too long.");
    220		kfree(lc);
    221		return -EINVAL;
    222	}
    223
    224	lc->usr_argc = argc;
    225
    226	strncpy(lc->uuid, argv[0], DM_UUID_LEN);
    227	argc--;
    228	argv++;
    229	spin_lock_init(&lc->flush_lock);
    230	INIT_LIST_HEAD(&lc->mark_list);
    231	INIT_LIST_HEAD(&lc->clear_list);
    232
    233	if (!strcasecmp(argv[0], "integrated_flush")) {
    234		lc->integrated_flush = 1;
    235		argc--;
    236		argv++;
    237	}
    238
    239	str_size = build_constructor_string(ti, argc, argv, &ctr_str);
    240	if (str_size < 0) {
    241		kfree(lc);
    242		return str_size;
    243	}
    244
    245	devices_rdata = kzalloc(devices_rdata_size, GFP_KERNEL);
    246	if (!devices_rdata) {
    247		DMERR("Failed to allocate memory for device information");
    248		r = -ENOMEM;
    249		goto out;
    250	}
    251
    252	r = mempool_init_slab_pool(&lc->flush_entry_pool, FLUSH_ENTRY_POOL_SIZE,
    253				   _flush_entry_cache);
    254	if (r) {
    255		DMERR("Failed to create flush_entry_pool");
    256		goto out;
    257	}
    258
    259	/*
    260	 * Send table string and get back any opened device.
    261	 */
    262	r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_CTR,
    263				 ctr_str, str_size,
    264				 devices_rdata, &devices_rdata_size);
    265
    266	if (r < 0) {
    267		if (r == -ESRCH)
    268			DMERR("Userspace log server not found");
    269		else
    270			DMERR("Userspace log server failed to create log");
    271		goto out;
    272	}
    273
    274	/* Since the region size does not change, get it now */
    275	rdata_size = sizeof(rdata);
    276	r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_GET_REGION_SIZE,
    277				 NULL, 0, (char *)&rdata, &rdata_size);
    278
    279	if (r) {
    280		DMERR("Failed to get region size of dirty log");
    281		goto out;
    282	}
    283
    284	lc->region_size = (uint32_t)rdata;
    285	lc->region_count = dm_sector_div_up(ti->len, lc->region_size);
    286
    287	if (devices_rdata_size) {
    288		if (devices_rdata[devices_rdata_size - 1] != '\0') {
    289			DMERR("DM_ULOG_CTR device return string not properly terminated");
    290			r = -EINVAL;
    291			goto out;
    292		}
    293		r = dm_get_device(ti, devices_rdata,
    294				  dm_table_get_mode(ti->table), &lc->log_dev);
    295		if (r)
    296			DMERR("Failed to register %s with device-mapper",
    297			      devices_rdata);
    298	}
    299
    300	if (lc->integrated_flush) {
    301		lc->dmlog_wq = alloc_workqueue("dmlogd", WQ_MEM_RECLAIM, 0);
    302		if (!lc->dmlog_wq) {
    303			DMERR("couldn't start dmlogd");
    304			r = -ENOMEM;
    305			goto out;
    306		}
    307
    308		INIT_DELAYED_WORK(&lc->flush_log_work, do_flush);
    309		atomic_set(&lc->sched_flush, 0);
    310	}
    311
    312out:
    313	kfree(devices_rdata);
    314	if (r) {
    315		mempool_exit(&lc->flush_entry_pool);
    316		kfree(lc);
    317		kfree(ctr_str);
    318	} else {
    319		lc->usr_argv_str = ctr_str;
    320		log->context = lc;
    321	}
    322
    323	return r;
    324}
    325
    326static void userspace_dtr(struct dm_dirty_log *log)
    327{
    328	struct log_c *lc = log->context;
    329
    330	if (lc->integrated_flush) {
    331		/* flush workqueue */
    332		if (atomic_read(&lc->sched_flush))
    333			flush_delayed_work(&lc->flush_log_work);
    334
    335		destroy_workqueue(lc->dmlog_wq);
    336	}
    337
    338	(void) dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_DTR,
    339				    NULL, 0, NULL, NULL);
    340
    341	if (lc->log_dev)
    342		dm_put_device(lc->ti, lc->log_dev);
    343
    344	mempool_exit(&lc->flush_entry_pool);
    345
    346	kfree(lc->usr_argv_str);
    347	kfree(lc);
    348
    349	return;
    350}
    351
    352static int userspace_presuspend(struct dm_dirty_log *log)
    353{
    354	int r;
    355	struct log_c *lc = log->context;
    356
    357	r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_PRESUSPEND,
    358				 NULL, 0, NULL, NULL);
    359
    360	return r;
    361}
    362
    363static int userspace_postsuspend(struct dm_dirty_log *log)
    364{
    365	int r;
    366	struct log_c *lc = log->context;
    367
    368	/*
    369	 * Run planned flush earlier.
    370	 */
    371	if (lc->integrated_flush && atomic_read(&lc->sched_flush))
    372		flush_delayed_work(&lc->flush_log_work);
    373
    374	r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_POSTSUSPEND,
    375				 NULL, 0, NULL, NULL);
    376
    377	return r;
    378}
    379
    380static int userspace_resume(struct dm_dirty_log *log)
    381{
    382	int r;
    383	struct log_c *lc = log->context;
    384
    385	lc->in_sync_hint = 0;
    386	r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_RESUME,
    387				 NULL, 0, NULL, NULL);
    388
    389	return r;
    390}
    391
    392static uint32_t userspace_get_region_size(struct dm_dirty_log *log)
    393{
    394	struct log_c *lc = log->context;
    395
    396	return lc->region_size;
    397}
    398
    399/*
    400 * userspace_is_clean
    401 *
    402 * Check whether a region is clean.  If there is any sort of
    403 * failure when consulting the server, we return not clean.
    404 *
    405 * Returns: 1 if clean, 0 otherwise
    406 */
    407static int userspace_is_clean(struct dm_dirty_log *log, region_t region)
    408{
    409	int r;
    410	uint64_t region64 = (uint64_t)region;
    411	int64_t is_clean;
    412	size_t rdata_size;
    413	struct log_c *lc = log->context;
    414
    415	rdata_size = sizeof(is_clean);
    416	r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_CLEAN,
    417				 (char *)&region64, sizeof(region64),
    418				 (char *)&is_clean, &rdata_size);
    419
    420	return (r) ? 0 : (int)is_clean;
    421}
    422
    423/*
    424 * userspace_in_sync
    425 *
    426 * Check if the region is in-sync.  If there is any sort
    427 * of failure when consulting the server, we assume that
    428 * the region is not in sync.
    429 *
    430 * If 'can_block' is set, return immediately
    431 *
    432 * Returns: 1 if in-sync, 0 if not-in-sync, -EWOULDBLOCK
    433 */
    434static int userspace_in_sync(struct dm_dirty_log *log, region_t region,
    435			     int can_block)
    436{
    437	int r;
    438	uint64_t region64 = region;
    439	int64_t in_sync;
    440	size_t rdata_size;
    441	struct log_c *lc = log->context;
    442
    443	/*
    444	 * We can never respond directly - even if in_sync_hint is
    445	 * set.  This is because another machine could see a device
    446	 * failure and mark the region out-of-sync.  If we don't go
    447	 * to userspace to ask, we might think the region is in-sync
    448	 * and allow a read to pick up data that is stale.  (This is
    449	 * very unlikely if a device actually fails; but it is very
    450	 * likely if a connection to one device from one machine fails.)
    451	 *
    452	 * There still might be a problem if the mirror caches the region
    453	 * state as in-sync... but then this call would not be made.  So,
    454	 * that is a mirror problem.
    455	 */
    456	if (!can_block)
    457		return -EWOULDBLOCK;
    458
    459	rdata_size = sizeof(in_sync);
    460	r = userspace_do_request(lc, lc->uuid, DM_ULOG_IN_SYNC,
    461				 (char *)&region64, sizeof(region64),
    462				 (char *)&in_sync, &rdata_size);
    463	return (r) ? 0 : (int)in_sync;
    464}
    465
    466static int flush_one_by_one(struct log_c *lc, struct list_head *flush_list)
    467{
    468	int r = 0;
    469	struct dm_dirty_log_flush_entry *fe;
    470
    471	list_for_each_entry(fe, flush_list, list) {
    472		r = userspace_do_request(lc, lc->uuid, fe->type,
    473					 (char *)&fe->region,
    474					 sizeof(fe->region),
    475					 NULL, NULL);
    476		if (r)
    477			break;
    478	}
    479
    480	return r;
    481}
    482
    483static int flush_by_group(struct log_c *lc, struct list_head *flush_list,
    484			  int flush_with_payload)
    485{
    486	int r = 0;
    487	int count;
    488	uint32_t type = 0;
    489	struct dm_dirty_log_flush_entry *fe, *tmp_fe;
    490	LIST_HEAD(tmp_list);
    491	uint64_t group[MAX_FLUSH_GROUP_COUNT];
    492
    493	/*
    494	 * Group process the requests
    495	 */
    496	while (!list_empty(flush_list)) {
    497		count = 0;
    498
    499		list_for_each_entry_safe(fe, tmp_fe, flush_list, list) {
    500			group[count] = fe->region;
    501			count++;
    502
    503			list_move(&fe->list, &tmp_list);
    504
    505			type = fe->type;
    506			if (count >= MAX_FLUSH_GROUP_COUNT)
    507				break;
    508		}
    509
    510		if (flush_with_payload) {
    511			r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,
    512						 (char *)(group),
    513						 count * sizeof(uint64_t),
    514						 NULL, NULL);
    515			/*
    516			 * Integrated flush failed.
    517			 */
    518			if (r)
    519				break;
    520		} else {
    521			r = userspace_do_request(lc, lc->uuid, type,
    522						 (char *)(group),
    523						 count * sizeof(uint64_t),
    524						 NULL, NULL);
    525			if (r) {
    526				/*
    527				 * Group send failed.  Attempt one-by-one.
    528				 */
    529				list_splice_init(&tmp_list, flush_list);
    530				r = flush_one_by_one(lc, flush_list);
    531				break;
    532			}
    533		}
    534	}
    535
    536	/*
    537	 * Must collect flush_entrys that were successfully processed
    538	 * as a group so that they will be free'd by the caller.
    539	 */
    540	list_splice_init(&tmp_list, flush_list);
    541
    542	return r;
    543}
    544
    545/*
    546 * userspace_flush
    547 *
    548 * This function is ok to block.
    549 * The flush happens in two stages.  First, it sends all
    550 * clear/mark requests that are on the list.  Then it
    551 * tells the server to commit them.  This gives the
    552 * server a chance to optimise the commit, instead of
    553 * doing it for every request.
    554 *
    555 * Additionally, we could implement another thread that
    556 * sends the requests up to the server - reducing the
    557 * load on flush.  Then the flush would have less in
    558 * the list and be responsible for the finishing commit.
    559 *
    560 * Returns: 0 on success, < 0 on failure
    561 */
    562static int userspace_flush(struct dm_dirty_log *log)
    563{
    564	int r = 0;
    565	unsigned long flags;
    566	struct log_c *lc = log->context;
    567	LIST_HEAD(mark_list);
    568	LIST_HEAD(clear_list);
    569	int mark_list_is_empty;
    570	int clear_list_is_empty;
    571	struct dm_dirty_log_flush_entry *fe, *tmp_fe;
    572	mempool_t *flush_entry_pool = &lc->flush_entry_pool;
    573
    574	spin_lock_irqsave(&lc->flush_lock, flags);
    575	list_splice_init(&lc->mark_list, &mark_list);
    576	list_splice_init(&lc->clear_list, &clear_list);
    577	spin_unlock_irqrestore(&lc->flush_lock, flags);
    578
    579	mark_list_is_empty = list_empty(&mark_list);
    580	clear_list_is_empty = list_empty(&clear_list);
    581
    582	if (mark_list_is_empty && clear_list_is_empty)
    583		return 0;
    584
    585	r = flush_by_group(lc, &clear_list, 0);
    586	if (r)
    587		goto out;
    588
    589	if (!lc->integrated_flush) {
    590		r = flush_by_group(lc, &mark_list, 0);
    591		if (r)
    592			goto out;
    593		r = userspace_do_request(lc, lc->uuid, DM_ULOG_FLUSH,
    594					 NULL, 0, NULL, NULL);
    595		goto out;
    596	}
    597
    598	/*
    599	 * Send integrated flush request with mark_list as payload.
    600	 */
    601	r = flush_by_group(lc, &mark_list, 1);
    602	if (r)
    603		goto out;
    604
    605	if (mark_list_is_empty && !atomic_read(&lc->sched_flush)) {
    606		/*
    607		 * When there are only clear region requests,
    608		 * we schedule a flush in the future.
    609		 */
    610		queue_delayed_work(lc->dmlog_wq, &lc->flush_log_work, 3 * HZ);
    611		atomic_set(&lc->sched_flush, 1);
    612	} else {
    613		/*
    614		 * Cancel pending flush because we
    615		 * have already flushed in mark_region.
    616		 */
    617		cancel_delayed_work(&lc->flush_log_work);
    618		atomic_set(&lc->sched_flush, 0);
    619	}
    620
    621out:
    622	/*
    623	 * We can safely remove these entries, even after failure.
    624	 * Calling code will receive an error and will know that
    625	 * the log facility has failed.
    626	 */
    627	list_for_each_entry_safe(fe, tmp_fe, &mark_list, list) {
    628		list_del(&fe->list);
    629		mempool_free(fe, flush_entry_pool);
    630	}
    631	list_for_each_entry_safe(fe, tmp_fe, &clear_list, list) {
    632		list_del(&fe->list);
    633		mempool_free(fe, flush_entry_pool);
    634	}
    635
    636	if (r)
    637		dm_table_event(lc->ti->table);
    638
    639	return r;
    640}
    641
    642/*
    643 * userspace_mark_region
    644 *
    645 * This function should avoid blocking unless absolutely required.
    646 * (Memory allocation is valid for blocking.)
    647 */
    648static void userspace_mark_region(struct dm_dirty_log *log, region_t region)
    649{
    650	unsigned long flags;
    651	struct log_c *lc = log->context;
    652	struct dm_dirty_log_flush_entry *fe;
    653
    654	/* Wait for an allocation, but _never_ fail */
    655	fe = mempool_alloc(&lc->flush_entry_pool, GFP_NOIO);
    656	BUG_ON(!fe);
    657
    658	spin_lock_irqsave(&lc->flush_lock, flags);
    659	fe->type = DM_ULOG_MARK_REGION;
    660	fe->region = region;
    661	list_add(&fe->list, &lc->mark_list);
    662	spin_unlock_irqrestore(&lc->flush_lock, flags);
    663
    664	return;
    665}
    666
    667/*
    668 * userspace_clear_region
    669 *
    670 * This function must not block.
    671 * So, the alloc can't block.  In the worst case, it is ok to
    672 * fail.  It would simply mean we can't clear the region.
    673 * Does nothing to current sync context, but does mean
    674 * the region will be re-sync'ed on a reload of the mirror
    675 * even though it is in-sync.
    676 */
    677static void userspace_clear_region(struct dm_dirty_log *log, region_t region)
    678{
    679	unsigned long flags;
    680	struct log_c *lc = log->context;
    681	struct dm_dirty_log_flush_entry *fe;
    682
    683	/*
    684	 * If we fail to allocate, we skip the clearing of
    685	 * the region.  This doesn't hurt us in any way, except
    686	 * to cause the region to be resync'ed when the
    687	 * device is activated next time.
    688	 */
    689	fe = mempool_alloc(&lc->flush_entry_pool, GFP_ATOMIC);
    690	if (!fe) {
    691		DMERR("Failed to allocate memory to clear region.");
    692		return;
    693	}
    694
    695	spin_lock_irqsave(&lc->flush_lock, flags);
    696	fe->type = DM_ULOG_CLEAR_REGION;
    697	fe->region = region;
    698	list_add(&fe->list, &lc->clear_list);
    699	spin_unlock_irqrestore(&lc->flush_lock, flags);
    700
    701	return;
    702}
    703
    704/*
    705 * userspace_get_resync_work
    706 *
    707 * Get a region that needs recovery.  It is valid to return
    708 * an error for this function.
    709 *
    710 * Returns: 1 if region filled, 0 if no work, <0 on error
    711 */
    712static int userspace_get_resync_work(struct dm_dirty_log *log, region_t *region)
    713{
    714	int r;
    715	size_t rdata_size;
    716	struct log_c *lc = log->context;
    717	struct {
    718		int64_t i; /* 64-bit for mix arch compatibility */
    719		region_t r;
    720	} pkg;
    721
    722	if (lc->in_sync_hint >= lc->region_count)
    723		return 0;
    724
    725	rdata_size = sizeof(pkg);
    726	r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_RESYNC_WORK,
    727				 NULL, 0, (char *)&pkg, &rdata_size);
    728
    729	*region = pkg.r;
    730	return (r) ? r : (int)pkg.i;
    731}
    732
    733/*
    734 * userspace_set_region_sync
    735 *
    736 * Set the sync status of a given region.  This function
    737 * must not fail.
    738 */
    739static void userspace_set_region_sync(struct dm_dirty_log *log,
    740				      region_t region, int in_sync)
    741{
    742	struct log_c *lc = log->context;
    743	struct {
    744		region_t r;
    745		int64_t i;
    746	} pkg;
    747
    748	pkg.r = region;
    749	pkg.i = (int64_t)in_sync;
    750
    751	(void) userspace_do_request(lc, lc->uuid, DM_ULOG_SET_REGION_SYNC,
    752				    (char *)&pkg, sizeof(pkg), NULL, NULL);
    753
    754	/*
    755	 * It would be nice to be able to report failures.
    756	 * However, it is easy enough to detect and resolve.
    757	 */
    758	return;
    759}
    760
    761/*
    762 * userspace_get_sync_count
    763 *
    764 * If there is any sort of failure when consulting the server,
    765 * we assume that the sync count is zero.
    766 *
    767 * Returns: sync count on success, 0 on failure
    768 */
    769static region_t userspace_get_sync_count(struct dm_dirty_log *log)
    770{
    771	int r;
    772	size_t rdata_size;
    773	uint64_t sync_count;
    774	struct log_c *lc = log->context;
    775
    776	rdata_size = sizeof(sync_count);
    777	r = userspace_do_request(lc, lc->uuid, DM_ULOG_GET_SYNC_COUNT,
    778				 NULL, 0, (char *)&sync_count, &rdata_size);
    779
    780	if (r)
    781		return 0;
    782
    783	if (sync_count >= lc->region_count)
    784		lc->in_sync_hint = lc->region_count;
    785
    786	return (region_t)sync_count;
    787}
    788
    789/*
    790 * userspace_status
    791 *
    792 * Returns: amount of space consumed
    793 */
    794static int userspace_status(struct dm_dirty_log *log, status_type_t status_type,
    795			    char *result, unsigned maxlen)
    796{
    797	int r = 0;
    798	char *table_args;
    799	size_t sz = (size_t)maxlen;
    800	struct log_c *lc = log->context;
    801
    802	switch (status_type) {
    803	case STATUSTYPE_INFO:
    804		r = userspace_do_request(lc, lc->uuid, DM_ULOG_STATUS_INFO,
    805					 NULL, 0, result, &sz);
    806
    807		if (r) {
    808			sz = 0;
    809			DMEMIT("%s 1 COM_FAILURE", log->type->name);
    810		}
    811		break;
    812	case STATUSTYPE_TABLE:
    813		sz = 0;
    814		table_args = strchr(lc->usr_argv_str, ' ');
    815		BUG_ON(!table_args); /* There will always be a ' ' */
    816		table_args++;
    817
    818		DMEMIT("%s %u %s ", log->type->name, lc->usr_argc, lc->uuid);
    819		if (lc->integrated_flush)
    820			DMEMIT("integrated_flush ");
    821		DMEMIT("%s ", table_args);
    822		break;
    823	case STATUSTYPE_IMA:
    824		*result = '\0';
    825		break;
    826	}
    827	return (r) ? 0 : (int)sz;
    828}
    829
    830/*
    831 * userspace_is_remote_recovering
    832 *
    833 * Returns: 1 if region recovering, 0 otherwise
    834 */
    835static int userspace_is_remote_recovering(struct dm_dirty_log *log,
    836					  region_t region)
    837{
    838	int r;
    839	uint64_t region64 = region;
    840	struct log_c *lc = log->context;
    841	static unsigned long limit;
    842	struct {
    843		int64_t is_recovering;
    844		uint64_t in_sync_hint;
    845	} pkg;
    846	size_t rdata_size = sizeof(pkg);
    847
    848	/*
    849	 * Once the mirror has been reported to be in-sync,
    850	 * it will never again ask for recovery work.  So,
    851	 * we can safely say there is not a remote machine
    852	 * recovering if the device is in-sync.  (in_sync_hint
    853	 * must be reset at resume time.)
    854	 */
    855	if (region < lc->in_sync_hint)
    856		return 0;
    857	else if (time_after(limit, jiffies))
    858		return 1;
    859
    860	limit = jiffies + (HZ / 4);
    861	r = userspace_do_request(lc, lc->uuid, DM_ULOG_IS_REMOTE_RECOVERING,
    862				 (char *)&region64, sizeof(region64),
    863				 (char *)&pkg, &rdata_size);
    864	if (r)
    865		return 1;
    866
    867	lc->in_sync_hint = pkg.in_sync_hint;
    868
    869	return (int)pkg.is_recovering;
    870}
    871
    872static struct dm_dirty_log_type _userspace_type = {
    873	.name = "userspace",
    874	.module = THIS_MODULE,
    875	.ctr = userspace_ctr,
    876	.dtr = userspace_dtr,
    877	.presuspend = userspace_presuspend,
    878	.postsuspend = userspace_postsuspend,
    879	.resume = userspace_resume,
    880	.get_region_size = userspace_get_region_size,
    881	.is_clean = userspace_is_clean,
    882	.in_sync = userspace_in_sync,
    883	.flush = userspace_flush,
    884	.mark_region = userspace_mark_region,
    885	.clear_region = userspace_clear_region,
    886	.get_resync_work = userspace_get_resync_work,
    887	.set_region_sync = userspace_set_region_sync,
    888	.get_sync_count = userspace_get_sync_count,
    889	.status = userspace_status,
    890	.is_remote_recovering = userspace_is_remote_recovering,
    891};
    892
    893static int __init userspace_dirty_log_init(void)
    894{
    895	int r = 0;
    896
    897	_flush_entry_cache = KMEM_CACHE(dm_dirty_log_flush_entry, 0);
    898	if (!_flush_entry_cache) {
    899		DMWARN("Unable to create flush_entry_cache: No memory.");
    900		return -ENOMEM;
    901	}
    902
    903	r = dm_ulog_tfr_init();
    904	if (r) {
    905		DMWARN("Unable to initialize userspace log communications");
    906		kmem_cache_destroy(_flush_entry_cache);
    907		return r;
    908	}
    909
    910	r = dm_dirty_log_type_register(&_userspace_type);
    911	if (r) {
    912		DMWARN("Couldn't register userspace dirty log type");
    913		dm_ulog_tfr_exit();
    914		kmem_cache_destroy(_flush_entry_cache);
    915		return r;
    916	}
    917
    918	DMINFO("version " DM_LOG_USERSPACE_VSN " loaded");
    919	return 0;
    920}
    921
    922static void __exit userspace_dirty_log_exit(void)
    923{
    924	dm_dirty_log_type_unregister(&_userspace_type);
    925	dm_ulog_tfr_exit();
    926	kmem_cache_destroy(_flush_entry_cache);
    927
    928	DMINFO("version " DM_LOG_USERSPACE_VSN " unloaded");
    929	return;
    930}
    931
    932module_init(userspace_dirty_log_init);
    933module_exit(userspace_dirty_log_exit);
    934
    935MODULE_DESCRIPTION(DM_NAME " userspace dirty log link");
    936MODULE_AUTHOR("Jonathan Brassow <dm-devel@redhat.com>");
    937MODULE_LICENSE("GPL");