dm persistent data: remove debug space map checker

Remove debug space map checker from dm persistent data.

The space map checker is a wrapper for other space maps that double
checks the reference counts are correct.  It holds all these reference
counts in memory rather than on disk, so uses a lot of memory and is
thus restricted to small pools.

As yet, this checker hasn't found any issues, but has caused a few of
its own due to people turning it on by default with larger pools.

Removing.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/Kconfig

@@ -260,15 +260,6 @@ config DM_DEBUG_BLOCK_STACK_TRACING
 
 	  If unsure, say N.
 
-config DM_DEBUG_SPACE_MAPS
-	boolean "Extra validation for thin provisioning space maps"
-	depends on DM_THIN_PROVISIONING
-	---help---
-	  Enable this for messages that may help debug problems with the
-	  space maps used by thin provisioning.
-
-          If unsure, say N.
-
 config DM_MIRROR
        tristate "Mirror target"
        depends on BLK_DEV_DM

drivers/md/persistent-data/Makefile

@@ -1,7 +1,6 @@
 obj-$(CONFIG_DM_PERSISTENT_DATA) += dm-persistent-data.o
 dm-persistent-data-objs := \
 	dm-block-manager.o \
-	dm-space-map-checker.o \
 	dm-space-map-common.o \
 	dm-space-map-disk.o \
 	dm-space-map-metadata.o \

drivers/md/persistent-data/dm-space-map-checker.c

@@ -1,446 +0,0 @@
-/*
- * Copyright (C) 2011 Red Hat, Inc.
- *
- * This file is released under the GPL.
- */
-
-#include "dm-space-map-checker.h"
-
-#include <linux/device-mapper.h>
-#include <linux/export.h>
-#include <linux/vmalloc.h>
-
-#ifdef CONFIG_DM_DEBUG_SPACE_MAPS
-
-#define DM_MSG_PREFIX "space map checker"
-
-/*----------------------------------------------------------------*/
-
-struct count_array {
-	dm_block_t nr;
-	dm_block_t nr_free;
-
-	uint32_t *counts;
-};
-
-static int ca_get_count(struct count_array *ca, dm_block_t b, uint32_t *count)
-{
-	if (b >= ca->nr)
-		return -EINVAL;
-
-	*count = ca->counts[b];
-	return 0;
-}
-
-static int ca_count_more_than_one(struct count_array *ca, dm_block_t b, int *r)
-{
-	if (b >= ca->nr)
-		return -EINVAL;
-
-	*r = ca->counts[b] > 1;
-	return 0;
-}
-
-static int ca_set_count(struct count_array *ca, dm_block_t b, uint32_t count)
-{
-	uint32_t old_count;
-
-	if (b >= ca->nr)
-		return -EINVAL;
-
-	old_count = ca->counts[b];
-
-	if (!count && old_count)
-		ca->nr_free++;
-
-	else if (count && !old_count)
-		ca->nr_free--;
-
-	ca->counts[b] = count;
-	return 0;
-}
-
-static int ca_inc_block(struct count_array *ca, dm_block_t b)
-{
-	if (b >= ca->nr)
-		return -EINVAL;
-
-	ca_set_count(ca, b, ca->counts[b] + 1);
-	return 0;
-}
-
-static int ca_dec_block(struct count_array *ca, dm_block_t b)
-{
-	if (b >= ca->nr)
-		return -EINVAL;
-
-	BUG_ON(ca->counts[b] == 0);
-	ca_set_count(ca, b, ca->counts[b] - 1);
-	return 0;
-}
-
-static int ca_create(struct count_array *ca, struct dm_space_map *sm)
-{
-	int r;
-	dm_block_t nr_blocks;
-
-	r = dm_sm_get_nr_blocks(sm, &nr_blocks);
-	if (r)
-		return r;
-
-	ca->nr = nr_blocks;
-	ca->nr_free = nr_blocks;
-
-	if (!nr_blocks)
-		ca->counts = NULL;
-	else {
-		ca->counts = vzalloc(sizeof(*ca->counts) * nr_blocks);
-		if (!ca->counts)
-			return -ENOMEM;
-	}
-
-	return 0;
-}
-
-static void ca_destroy(struct count_array *ca)
-{
-	vfree(ca->counts);
-}
-
-static int ca_load(struct count_array *ca, struct dm_space_map *sm)
-{
-	int r;
-	uint32_t count;
-	dm_block_t nr_blocks, i;
-
-	r = dm_sm_get_nr_blocks(sm, &nr_blocks);
-	if (r)
-		return r;
-
-	BUG_ON(ca->nr != nr_blocks);
-
-	DMWARN("Loading debug space map from disk.  This may take some time");
-	for (i = 0; i < nr_blocks; i++) {
-		r = dm_sm_get_count(sm, i, &count);
-		if (r) {
-			DMERR("load failed");
-			return r;
-		}
-
-		ca_set_count(ca, i, count);
-	}
-	DMWARN("Load complete");
-
-	return 0;
-}
-
-static int ca_extend(struct count_array *ca, dm_block_t extra_blocks)
-{
-	dm_block_t nr_blocks = ca->nr + extra_blocks;
-	uint32_t *counts = vzalloc(sizeof(*counts) * nr_blocks);
-	if (!counts)
-		return -ENOMEM;
-
-	if (ca->counts) {
-		memcpy(counts, ca->counts, sizeof(*counts) * ca->nr);
-		ca_destroy(ca);
-	}
-	ca->nr = nr_blocks;
-	ca->nr_free += extra_blocks;
-	ca->counts = counts;
-	return 0;
-}
-
-static int ca_commit(struct count_array *old, struct count_array *new)
-{
-	if (old->nr != new->nr) {
-		BUG_ON(old->nr > new->nr);
-		ca_extend(old, new->nr - old->nr);
-	}
-
-	BUG_ON(old->nr != new->nr);
-	old->nr_free = new->nr_free;
-	memcpy(old->counts, new->counts, sizeof(*old->counts) * old->nr);
-	return 0;
-}
-
-/*----------------------------------------------------------------*/
-
-struct sm_checker {
-	struct dm_space_map sm;
-
-	struct count_array old_counts;
-	struct count_array counts;
-
-	struct dm_space_map *real_sm;
-};
-
-static void sm_checker_destroy(struct dm_space_map *sm)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-
-	dm_sm_destroy(smc->real_sm);
-	ca_destroy(&smc->old_counts);
-	ca_destroy(&smc->counts);
-	kfree(smc);
-}
-
-static int sm_checker_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	int r = dm_sm_get_nr_blocks(smc->real_sm, count);
-	if (!r)
-		BUG_ON(smc->old_counts.nr != *count);
-	return r;
-}
-
-static int sm_checker_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	int r = dm_sm_get_nr_free(smc->real_sm, count);
-	if (!r) {
-		/*
-		 * Slow, but we know it's correct.
-		 */
-		dm_block_t b, n = 0;
-		for (b = 0; b < smc->old_counts.nr; b++)
-			if (smc->old_counts.counts[b] == 0 &&
-			    smc->counts.counts[b] == 0)
-				n++;
-
-		if (n != *count)
-			DMERR("free block counts differ, checker %u, sm-disk:%u",
-			      (unsigned) n, (unsigned) *count);
-	}
-	return r;
-}
-
-static int sm_checker_new_block(struct dm_space_map *sm, dm_block_t *b)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	int r = dm_sm_new_block(smc->real_sm, b);
-
-	if (!r) {
-		BUG_ON(*b >= smc->old_counts.nr);
-		BUG_ON(smc->old_counts.counts[*b] != 0);
-		BUG_ON(*b >= smc->counts.nr);
-		BUG_ON(smc->counts.counts[*b] != 0);
-		ca_set_count(&smc->counts, *b, 1);
-	}
-
-	return r;
-}
-
-static int sm_checker_inc_block(struct dm_space_map *sm, dm_block_t b)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	int r = dm_sm_inc_block(smc->real_sm, b);
-	int r2 = ca_inc_block(&smc->counts, b);
-	BUG_ON(r != r2);
-	return r;
-}
-
-static int sm_checker_dec_block(struct dm_space_map *sm, dm_block_t b)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	int r = dm_sm_dec_block(smc->real_sm, b);
-	int r2 = ca_dec_block(&smc->counts, b);
-	BUG_ON(r != r2);
-	return r;
-}
-
-static int sm_checker_get_count(struct dm_space_map *sm, dm_block_t b, uint32_t *result)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	uint32_t result2 = 0;
-	int r = dm_sm_get_count(smc->real_sm, b, result);
-	int r2 = ca_get_count(&smc->counts, b, &result2);
-
-	BUG_ON(r != r2);
-	if (!r)
-		BUG_ON(*result != result2);
-	return r;
-}
-
-static int sm_checker_count_more_than_one(struct dm_space_map *sm, dm_block_t b, int *result)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	int result2 = 0;
-	int r = dm_sm_count_is_more_than_one(smc->real_sm, b, result);
-	int r2 = ca_count_more_than_one(&smc->counts, b, &result2);
-
-	BUG_ON(r != r2);
-	if (!r)
-		BUG_ON(!(*result) && result2);
-	return r;
-}
-
-static int sm_checker_set_count(struct dm_space_map *sm, dm_block_t b, uint32_t count)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	uint32_t old_rc;
-	int r = dm_sm_set_count(smc->real_sm, b, count);
-	int r2;
-
-	BUG_ON(b >= smc->counts.nr);
-	old_rc = smc->counts.counts[b];
-	r2 = ca_set_count(&smc->counts, b, count);
-	BUG_ON(r != r2);
-
-	return r;
-}
-
-static int sm_checker_commit(struct dm_space_map *sm)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	int r;
-
-	r = dm_sm_commit(smc->real_sm);
-	if (r)
-		return r;
-
-	r = ca_commit(&smc->old_counts, &smc->counts);
-	if (r)
-		return r;
-
-	return 0;
-}
-
-static int sm_checker_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	int r = dm_sm_extend(smc->real_sm, extra_blocks);
-	if (r)
-		return r;
-
-	return ca_extend(&smc->counts, extra_blocks);
-}
-
-static int sm_checker_root_size(struct dm_space_map *sm, size_t *result)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	return dm_sm_root_size(smc->real_sm, result);
-}
-
-static int sm_checker_copy_root(struct dm_space_map *sm, void *copy_to_here_le, size_t len)
-{
-	struct sm_checker *smc = container_of(sm, struct sm_checker, sm);
-	return dm_sm_copy_root(smc->real_sm, copy_to_here_le, len);
-}
-
-/*----------------------------------------------------------------*/
-
-static struct dm_space_map ops_ = {
-	.destroy = sm_checker_destroy,
-	.get_nr_blocks = sm_checker_get_nr_blocks,
-	.get_nr_free = sm_checker_get_nr_free,
-	.inc_block = sm_checker_inc_block,
-	.dec_block = sm_checker_dec_block,
-	.new_block = sm_checker_new_block,
-	.get_count = sm_checker_get_count,
-	.count_is_more_than_one = sm_checker_count_more_than_one,
-	.set_count = sm_checker_set_count,
-	.commit = sm_checker_commit,
-	.extend = sm_checker_extend,
-	.root_size = sm_checker_root_size,
-	.copy_root = sm_checker_copy_root
-};
-
-struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
-{
-	int r;
-	struct sm_checker *smc;
-
-	if (IS_ERR_OR_NULL(sm))
-		return ERR_PTR(-EINVAL);
-
-	smc = kmalloc(sizeof(*smc), GFP_KERNEL);
-	if (!smc)
-		return ERR_PTR(-ENOMEM);
-
-	memcpy(&smc->sm, &ops_, sizeof(smc->sm));
-	r = ca_create(&smc->old_counts, sm);
-	if (r) {
-		kfree(smc);
-		return ERR_PTR(r);
-	}
-
-	r = ca_create(&smc->counts, sm);
-	if (r) {
-		ca_destroy(&smc->old_counts);
-		kfree(smc);
-		return ERR_PTR(r);
-	}
-
-	smc->real_sm = sm;
-
-	r = ca_load(&smc->counts, sm);
-	if (r) {
-		ca_destroy(&smc->counts);
-		ca_destroy(&smc->old_counts);
-		kfree(smc);
-		return ERR_PTR(r);
-	}
-
-	r = ca_commit(&smc->old_counts, &smc->counts);
-	if (r) {
-		ca_destroy(&smc->counts);
-		ca_destroy(&smc->old_counts);
-		kfree(smc);
-		return ERR_PTR(r);
-	}
-
-	return &smc->sm;
-}
-EXPORT_SYMBOL_GPL(dm_sm_checker_create);
-
-struct dm_space_map *dm_sm_checker_create_fresh(struct dm_space_map *sm)
-{
-	int r;
-	struct sm_checker *smc;
-
-	if (IS_ERR_OR_NULL(sm))
-		return ERR_PTR(-EINVAL);
-
-	smc = kmalloc(sizeof(*smc), GFP_KERNEL);
-	if (!smc)
-		return ERR_PTR(-ENOMEM);
-
-	memcpy(&smc->sm, &ops_, sizeof(smc->sm));
-	r = ca_create(&smc->old_counts, sm);
-	if (r) {
-		kfree(smc);
-		return ERR_PTR(r);
-	}
-
-	r = ca_create(&smc->counts, sm);
-	if (r) {
-		ca_destroy(&smc->old_counts);
-		kfree(smc);
-		return ERR_PTR(r);
-	}
-
-	smc->real_sm = sm;
-	return &smc->sm;
-}
-EXPORT_SYMBOL_GPL(dm_sm_checker_create_fresh);
-
-/*----------------------------------------------------------------*/
-
-#else
-
-struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
-{
-	return sm;
-}
-EXPORT_SYMBOL_GPL(dm_sm_checker_create);
-
-struct dm_space_map *dm_sm_checker_create_fresh(struct dm_space_map *sm)
-{
-	return sm;
-}
-EXPORT_SYMBOL_GPL(dm_sm_checker_create_fresh);
-
-/*----------------------------------------------------------------*/
-
-#endif

drivers/md/persistent-data/dm-space-map-checker.h

@@ -1,26 +0,0 @@
-/*
- * Copyright (C) 2011 Red Hat, Inc.
- *
- * This file is released under the GPL.
- */
-
-#ifndef SNAPSHOTS_SPACE_MAP_CHECKER_H
-#define SNAPSHOTS_SPACE_MAP_CHECKER_H
-
-#include "dm-space-map.h"
-
-/*----------------------------------------------------------------*/
-
-/*
- * This space map wraps a real on-disk space map, and verifies all of its
- * operations.  It uses a lot of memory, so only use if you have a specific
- * problem that you're debugging.
- *
- * Ownership of @sm passes.
- */
-struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm);
-struct dm_space_map *dm_sm_checker_create_fresh(struct dm_space_map *sm);
-
-/*----------------------------------------------------------------*/
-
-#endif

drivers/md/persistent-data/dm-space-map-disk.c

@@ -4,7 +4,6 @@
  * This file is released under the GPL.
  */
 
-#include "dm-space-map-checker.h"
 #include "dm-space-map-common.h"
 #include "dm-space-map-disk.h"
 #include "dm-space-map.h"
@@ -252,9 +251,8 @@ static struct dm_space_map ops = {
 	.copy_root = sm_disk_copy_root
 };
 
-static struct dm_space_map *dm_sm_disk_create_real(
-	struct dm_transaction_manager *tm,
-	dm_block_t nr_blocks)
+struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
+				       dm_block_t nr_blocks)
 {
 	int r;
 	struct sm_disk *smd;
@@ -285,27 +283,10 @@ bad:
 	kfree(smd);
 	return ERR_PTR(r);
 }
-
-struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
-				       dm_block_t nr_blocks)
-{
-	struct dm_space_map *sm = dm_sm_disk_create_real(tm, nr_blocks);
-	struct dm_space_map *smc;
-
-	if (IS_ERR_OR_NULL(sm))
-		return sm;
-
-	smc = dm_sm_checker_create_fresh(sm);
-	if (IS_ERR(smc))
-		dm_sm_destroy(sm);
-
-	return smc;
-}
 EXPORT_SYMBOL_GPL(dm_sm_disk_create);
 
-static struct dm_space_map *dm_sm_disk_open_real(
-	struct dm_transaction_manager *tm,
-	void *root_le, size_t len)
+struct dm_space_map *dm_sm_disk_open(struct dm_transaction_manager *tm,
+				     void *root_le, size_t len)
 {
 	int r;
 	struct sm_disk *smd;
@@ -332,13 +313,6 @@ bad:
 	kfree(smd);
 	return ERR_PTR(r);
 }
-
-struct dm_space_map *dm_sm_disk_open(struct dm_transaction_manager *tm,
-				     void *root_le, size_t len)
-{
-	return dm_sm_checker_create(
-		dm_sm_disk_open_real(tm, root_le, len));
-}
 EXPORT_SYMBOL_GPL(dm_sm_disk_open);
 
 /*----------------------------------------------------------------*/

drivers/md/persistent-data/dm-transaction-manager.c

@@ -5,7 +5,6 @@
  */
 #include "dm-transaction-manager.h"
 #include "dm-space-map.h"
-#include "dm-space-map-checker.h"
 #include "dm-space-map-disk.h"
 #include "dm-space-map-metadata.h"
 #include "dm-persistent-data-internal.h"
@@ -319,15 +318,14 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
 				 int create)
 {
 	int r;
-	struct dm_space_map *inner;
 
-	inner = dm_sm_metadata_init();
-	if (IS_ERR(inner))
-		return PTR_ERR(inner);
+	*sm = dm_sm_metadata_init();
+	if (IS_ERR(*sm))
+		return PTR_ERR(*sm);
 
-	*tm = dm_tm_create(bm, inner);
+	*tm = dm_tm_create(bm, *sm);
 	if (IS_ERR(*tm)) {
-		dm_sm_destroy(inner);
+		dm_sm_destroy(*sm);
 		return PTR_ERR(*tm);
 	}
 
@@ -339,19 +337,13 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
 			goto bad1;
 		}
 
-		r = dm_sm_metadata_create(inner, *tm, dm_bm_nr_blocks(bm),
+		r = dm_sm_metadata_create(*sm, *tm, dm_bm_nr_blocks(bm),
 					  sb_location);
 		if (r) {
 			DMERR("couldn't create metadata space map");
 			goto bad2;
 		}
 
-		*sm = dm_sm_checker_create(inner);
-		if (IS_ERR(*sm)) {
-			r = PTR_ERR(*sm);
-			goto bad2;
-		}
-
 	} else {
 		r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
 				     sb_validator, sblock);
@@ -360,19 +352,13 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
 			goto bad1;
 		}
 
-		r = dm_sm_metadata_open(inner, *tm,
+		r = dm_sm_metadata_open(*sm, *tm,
 					dm_block_data(*sblock) + root_offset,
 					root_max_len);
 		if (r) {
 			DMERR("couldn't open metadata space map");
 			goto bad2;
 		}
-
-		*sm = dm_sm_checker_create(inner);
-		if (IS_ERR(*sm)) {
-			r = PTR_ERR(*sm);
-			goto bad2;
-		}
 	}
 
 	return 0;
@@ -381,7 +367,6 @@ bad2:
 	dm_tm_unlock(*tm, *sblock);
 bad1:
 	dm_tm_destroy(*tm);
-	dm_sm_destroy(inner);
 	return r;
 }