Release 4.7 drivers/md/persistent-data/dm-space-map-metadata.c

Directory: drivers/md/persistent-data
/*
 * Copyright (C) 2011 Red Hat, Inc.
 *
 * This file is released under the GPL.
 */

#include "dm-space-map.h"
#include "dm-space-map-common.h"
#include "dm-space-map-metadata.h"

#include <linux/list.h>
#include <linux/slab.h>
#include <linux/device-mapper.h>


#define DM_MSG_PREFIX "space map metadata"

/*----------------------------------------------------------------*/

/*
 * An edge triggered threshold.
 */

struct threshold {
	
bool threshold_set;
	
bool value_set;
	
dm_block_t threshold;
	
dm_block_t current_value;
	
dm_sm_threshold_fn fn;
	
void *context;
};



static void threshold_init(struct threshold *t)
{
	t->threshold_set = false;
	t->value_set = false;
}

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static void set_threshold(struct threshold *t, dm_block_t value,
			  dm_sm_threshold_fn fn, void *context)
{
	t->threshold_set = true;
	t->threshold = value;
	t->fn = fn;
	t->context = context;
}

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static bool below_threshold(struct threshold *t, dm_block_t value)
{
	return t->threshold_set && value <= t->threshold;
}

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static bool threshold_already_triggered(struct threshold *t)
{
	return t->value_set && below_threshold(t, t->current_value);
}

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static void check_threshold(struct threshold *t, dm_block_t value)
{
	if (below_threshold(t, value) &&
	    !threshold_already_triggered(t))
		t->fn(t->context);

	t->value_set = true;
	t->current_value = value;
}

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/*----------------------------------------------------------------*/

/*
 * Space map interface.
 *
 * The low level disk format is written using the standard btree and
 * transaction manager.  This means that performing disk operations may
 * cause us to recurse into the space map in order to allocate new blocks.
 * For this reason we have a pool of pre-allocated blocks large enough to
 * service any metadata_ll_disk operation.
 */

/*
 * FIXME: we should calculate this based on the size of the device.
 * Only the metadata space map needs this functionality.
 */

#define MAX_RECURSIVE_ALLOCATIONS 1024


enum block_op_type {
	
BOP_INC,
	
BOP_DEC
};


struct block_op {
	
enum block_op_type type;
	
dm_block_t block;
};


struct bop_ring_buffer {
	
unsigned begin;
	
unsigned end;
	
struct block_op bops[MAX_RECURSIVE_ALLOCATIONS + 1];
};



static void brb_init(struct bop_ring_buffer *brb)
{
	brb->begin = 0;
	brb->end = 0;
}

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static bool brb_empty(struct bop_ring_buffer *brb)
{
	return brb->begin == brb->end;
}

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static unsigned brb_next(struct bop_ring_buffer *brb, unsigned old)
{
	unsigned r = old + 1;
	return (r >= (sizeof(brb->bops) / sizeof(*brb->bops))) ? 0 : r;
}

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static int brb_push(struct bop_ring_buffer *brb,
		    enum block_op_type type, dm_block_t b)
{
	struct block_op *bop;
	unsigned next = brb_next(brb, brb->end);

	/*
         * We don't allow the last bop to be filled, this way we can
         * differentiate between full and empty.
         */
	if (next == brb->begin)
		return -ENOMEM;

	bop = brb->bops + brb->end;
	bop->type = type;
	bop->block = b;

	brb->end = next;

	return 0;
}

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static int brb_peek(struct bop_ring_buffer *brb, struct block_op *result)
{
	struct block_op *bop;

	if (brb_empty(brb))
		return -ENODATA;

	bop = brb->bops + brb->begin;
	result->type = bop->type;
	result->block = bop->block;

	return 0;
}

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static int brb_pop(struct bop_ring_buffer *brb)
{
	if (brb_empty(brb))
		return -ENODATA;

	brb->begin = brb_next(brb, brb->begin);

	return 0;
}

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/*----------------------------------------------------------------*/


struct sm_metadata {
	
struct dm_space_map sm;

	
struct ll_disk ll;
	
struct ll_disk old_ll;

	
dm_block_t begin;

	
unsigned recursion_count;
	
unsigned allocated_this_transaction;
	
struct bop_ring_buffer uncommitted;

	
struct threshold threshold;
};



static int add_bop(struct sm_metadata *smm, enum block_op_type type, dm_block_t b)
{
	int r = brb_push(&smm->uncommitted, type, b);

	if (r) {
		DMERR("too many recursive allocations");
		return -ENOMEM;
	}

	return 0;
}

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static int commit_bop(struct sm_metadata *smm, struct block_op *op)
{
	int r = 0;
	enum allocation_event ev;

	switch (op->type) {
	case BOP_INC:
		r = sm_ll_inc(&smm->ll, op->block, &ev);
		break;

	case BOP_DEC:
		r = sm_ll_dec(&smm->ll, op->block, &ev);
		break;
	}

	return r;
}

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static void in(struct sm_metadata *smm)
{
	smm->recursion_count++;
}

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static int apply_bops(struct sm_metadata *smm)
{
	int r = 0;

	while (!brb_empty(&smm->uncommitted)) {
		struct block_op bop;

		r = brb_peek(&smm->uncommitted, &bop);
		if (r) {
			DMERR("bug in bop ring buffer");
			break;
		}

		r = commit_bop(smm, &bop);
		if (r)
			break;

		brb_pop(&smm->uncommitted);
	}

	return r;
}

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static int out(struct sm_metadata *smm)
{
	int r = 0;

	/*
         * If we're not recursing then very bad things are happening.
         */
	if (!smm->recursion_count) {
		DMERR("lost track of recursion depth");
		return -ENOMEM;
	}

	if (smm->recursion_count == 1)
		apply_bops(smm);

	smm->recursion_count--;

	return r;
}

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/*
 * When using the out() function above, we often want to combine an error
 * code for the operation run in the recursive context with that from
 * out().
 */


static int combine_errors(int r1, int r2)
{
	return r1 ? r1 : r2;
}

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static int recursing(struct sm_metadata *smm)
{
	return smm->recursion_count;
}

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static void sm_metadata_destroy(struct dm_space_map *sm)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	kfree(smm);
}

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static int sm_metadata_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	*count = smm->ll.nr_blocks;

	return 0;
}

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static int sm_metadata_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	*count = smm->old_ll.nr_blocks - smm->old_ll.nr_allocated -
		 smm->allocated_this_transaction;

	return 0;
}

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static int sm_metadata_get_count(struct dm_space_map *sm, dm_block_t b,
				 uint32_t *result)
{
	int r;
	unsigned i;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
	unsigned adjustment = 0;

	/*
         * We may have some uncommitted adjustments to add.  This list
         * should always be really short.
         */
	for (i = smm->uncommitted.begin;
	     i != smm->uncommitted.end;
	     i = brb_next(&smm->uncommitted, i)) {
		struct block_op *op = smm->uncommitted.bops + i;

		if (op->block != b)
			continue;

		switch (op->type) {
		case BOP_INC:
			adjustment++;
			break;

		case BOP_DEC:
			adjustment--;
			break;
		}
	}

	r = sm_ll_lookup(&smm->ll, b, result);
	if (r)
		return r;

	*result += adjustment;

	return 0;
}

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static int sm_metadata_count_is_more_than_one(struct dm_space_map *sm,
					      dm_block_t b, int *result)
{
	int r, adjustment = 0;
	unsigned i;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
	uint32_t rc;

	/*
         * We may have some uncommitted adjustments to add.  This list
         * should always be really short.
         */
	for (i = smm->uncommitted.begin;
	     i != smm->uncommitted.end;
	     i = brb_next(&smm->uncommitted, i)) {

		struct block_op *op = smm->uncommitted.bops + i;

		if (op->block != b)
			continue;

		switch (op->type) {
		case BOP_INC:
			adjustment++;
			break;

		case BOP_DEC:
			adjustment--;
			break;
		}
	}

	if (adjustment > 1) {
		*result = 1;
		return 0;
	}

	r = sm_ll_lookup_bitmap(&smm->ll, b, &rc);
	if (r)
		return r;

	if (rc == 3)
		/*
                 * We err on the side of caution, and always return true.
                 */
		*result = 1;
	else
		*result = rc + adjustment > 1;

	return 0;
}

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static int sm_metadata_set_count(struct dm_space_map *sm, dm_block_t b,
				 uint32_t count)
{
	int r, r2;
	enum allocation_event ev;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	if (smm->recursion_count) {
		DMERR("cannot recurse set_count()");
		return -EINVAL;
	}

	in(smm);
	r = sm_ll_insert(&smm->ll, b, count, &ev);
	r2 = out(smm);

	return combine_errors(r, r2);
}

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static int sm_metadata_inc_block(struct dm_space_map *sm, dm_block_t b)
{
	int r, r2 = 0;
	enum allocation_event ev;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	if (recursing(smm))
		r = add_bop(smm, BOP_INC, b);
	else {
		in(smm);
		r = sm_ll_inc(&smm->ll, b, &ev);
		r2 = out(smm);
	}

	return combine_errors(r, r2);
}

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static int sm_metadata_dec_block(struct dm_space_map *sm, dm_block_t b)
{
	int r, r2 = 0;
	enum allocation_event ev;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	if (recursing(smm))
		r = add_bop(smm, BOP_DEC, b);
	else {
		in(smm);
		r = sm_ll_dec(&smm->ll, b, &ev);
		r2 = out(smm);
	}

	return combine_errors(r, r2);
}

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static int sm_metadata_new_block_(struct dm_space_map *sm, dm_block_t *b)
{
	int r, r2 = 0;
	enum allocation_event ev;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	r = sm_ll_find_free_block(&smm->old_ll, smm->begin, smm->old_ll.nr_blocks, b);
	if (r)
		return r;

	smm->begin = *b + 1;

	if (recursing(smm))
		r = add_bop(smm, BOP_INC, *b);
	else {
		in(smm);
		r = sm_ll_inc(&smm->ll, *b, &ev);
		r2 = out(smm);
	}

	if (!r)
		smm->allocated_this_transaction++;

	return combine_errors(r, r2);
}

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static int sm_metadata_new_block(struct dm_space_map *sm, dm_block_t *b)
{
	dm_block_t count;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	int r = sm_metadata_new_block_(sm, b);
	if (r) {
		DMERR_LIMIT("unable to allocate new metadata block");
		return r;
	}

	r = sm_metadata_get_nr_free(sm, &count);
	if (r) {
		DMERR_LIMIT("couldn't get free block count");
		return r;
	}

	check_threshold(&smm->threshold, count);

	return r;
}

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static int sm_metadata_commit(struct dm_space_map *sm)
{
	int r;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	r = sm_ll_commit(&smm->ll);
	if (r)
		return r;

	memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
	smm->begin = 0;
	smm->allocated_this_transaction = 0;

	return 0;
}

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static int sm_metadata_register_threshold_callback(struct dm_space_map *sm,
						   dm_block_t threshold,
						   dm_sm_threshold_fn fn,
						   void *context)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	set_threshold(&smm->threshold, threshold, fn, context);

	return 0;
}

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static int sm_metadata_root_size(struct dm_space_map *sm, size_t *result)
{
	*result = sizeof(struct disk_sm_root);

	return 0;
}

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static int sm_metadata_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
	struct disk_sm_root root_le;

	root_le.nr_blocks = cpu_to_le64(smm->ll.nr_blocks);
	root_le.nr_allocated = cpu_to_le64(smm->ll.nr_allocated);
	root_le.bitmap_root = cpu_to_le64(smm->ll.bitmap_root);
	root_le.ref_count_root = cpu_to_le64(smm->ll.ref_count_root);

	if (max < sizeof(root_le))
		return -ENOSPC;

	memcpy(where_le, &root_le, sizeof(root_le));

	return 0;
}

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static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks);


static struct dm_space_map ops = {
	.destroy = sm_metadata_destroy,
	.extend = sm_metadata_extend,
	.get_nr_blocks = sm_metadata_get_nr_blocks,
	.get_nr_free = sm_metadata_get_nr_free,
	.get_count = sm_metadata_get_count,
	.count_is_more_than_one = sm_metadata_count_is_more_than_one,
	.set_count = sm_metadata_set_count,
	.inc_block = sm_metadata_inc_block,
	.dec_block = sm_metadata_dec_block,
	.new_block = sm_metadata_new_block,
	.commit = sm_metadata_commit,
	.root_size = sm_metadata_root_size,
	.copy_root = sm_metadata_copy_root,
	.register_threshold_callback = sm_metadata_register_threshold_callback
};

/*----------------------------------------------------------------*/

/*
 * When a new space map is created that manages its own space.  We use
 * this tiny bootstrap allocator.
 */


static void sm_bootstrap_destroy(struct dm_space_map *sm)
{
}

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static int sm_bootstrap_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
{
	DMERR("bootstrap doesn't support extend");

	return -EINVAL;
}

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static int sm_bootstrap_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	*count = smm->ll.nr_blocks;

	return 0;
}

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dan carpenter dan carpenter 6 14.29% 1 50.00%
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static int sm_bootstrap_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	*count = smm->ll.nr_blocks - smm->begin;

	return 0;
}

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static int sm_bootstrap_get_count(struct dm_space_map *sm, dm_block_t b,
				  uint32_t *result)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	*result = (b < smm->begin) ? 1 : 0;

	return 0;
}

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static int sm_bootstrap_count_is_more_than_one(struct dm_space_map *sm,
					       dm_block_t b, int *result)
{
	*result = 0;

	return 0;
}

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static int sm_bootstrap_set_count(struct dm_space_map *sm, dm_block_t b,
				  uint32_t count)
{
	DMERR("bootstrap doesn't support set_count");

	return -EINVAL;
}

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static int sm_bootstrap_new_block(struct dm_space_map *sm, dm_block_t *b)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	/*
         * We know the entire device is unused.
         */
	if (smm->begin == smm->ll.nr_blocks)
		return -ENOSPC;

	*b = smm->begin++;

	return 0;
}

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static int sm_bootstrap_inc_block(struct dm_space_map *sm, dm_block_t b)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	return add_bop(smm, BOP_INC, b);
}

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static int sm_bootstrap_dec_block(struct dm_space_map *sm, dm_block_t b)
{
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	return add_bop(smm, BOP_DEC, b);
}

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static int sm_bootstrap_commit(struct dm_space_map *sm)
{
	return 0;
}

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static int sm_bootstrap_root_size(struct dm_space_map *sm, size_t *result)
{
	DMERR("bootstrap doesn't support root_size");

	return -EINVAL;
}

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static int sm_bootstrap_copy_root(struct dm_space_map *sm, void *where,
				  size_t max)
{
	DMERR("bootstrap doesn't support copy_root");

	return -EINVAL;
}

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static struct dm_space_map bootstrap_ops = {
	.destroy = sm_bootstrap_destroy,
	.extend = sm_bootstrap_extend,
	.get_nr_blocks = sm_bootstrap_get_nr_blocks,
	.get_nr_free = sm_bootstrap_get_nr_free,
	.get_count = sm_bootstrap_get_count,
	.count_is_more_than_one = sm_bootstrap_count_is_more_than_one,
	.set_count = sm_bootstrap_set_count,
	.inc_block = sm_bootstrap_inc_block,
	.dec_block = sm_bootstrap_dec_block,
	.new_block = sm_bootstrap_new_block,
	.commit = sm_bootstrap_commit,
	.root_size = sm_bootstrap_root_size,
	.copy_root = sm_bootstrap_copy_root,
	.register_threshold_callback = NULL
};

/*----------------------------------------------------------------*/



static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
{
	int r, i;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
	dm_block_t old_len = smm->ll.nr_blocks;

	/*
         * Flick into a mode where all blocks get allocated in the new area.
         */
	smm->begin = old_len;
	memcpy(sm, &bootstrap_ops, sizeof(*sm));

	/*
         * Extend.
         */
	r = sm_ll_extend(&smm->ll, extra_blocks);
	if (r)
		goto out;

	/*
         * We repeatedly increment then commit until the commit doesn't
         * allocate any new blocks.
         */
	do {
		for (i = old_len; !r && i < smm->begin; i++)
			r = add_bop(smm, BOP_INC, i);

		if (r)
			goto out;

		old_len = smm->begin;

		r = apply_bops(smm);
		if (r) {
			DMERR("%s: apply_bops failed", __func__);
			goto out;
		}

		r = sm_ll_commit(&smm->ll);
		if (r)
			goto out;

	} while (old_len != smm->begin);

out:
	/*
         * Switch back to normal behaviour.
         */
	memcpy(sm, &ops, sizeof(*sm));
	return r;
}

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Person Tokens Prop Commits CommitProp
joe thornber joe thornber 199 100.00% 5 100.00%
Total 199 100.00% 5 100.00%

/*----------------------------------------------------------------*/



struct dm_space_map *dm_sm_metadata_init(void)
{
	struct sm_metadata *smm;

	smm = kmalloc(sizeof(*smm), GFP_KERNEL);
	if (!smm)
		return ERR_PTR(-ENOMEM);

	memcpy(&smm->sm, &ops, sizeof(smm->sm));

	return &smm->sm;
}

Contributors
Person Tokens Prop Commits CommitProp
joe thornber joe thornber 63 100.00% 1 100.00%
Total 63 100.00% 1 100.00%



int dm_sm_metadata_create(struct dm_space_map *sm,
			  struct dm_transaction_manager *tm,
			  dm_block_t nr_blocks,
			  dm_block_t superblock)
{
	int r;
	dm_block_t i;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	smm->begin = superblock + 1;
	smm->recursion_count = 0;
	smm->allocated_this_transaction = 0;
	brb_init(&smm->uncommitted);
	threshold_init(&smm->threshold);

	memcpy(&smm->sm, &bootstrap_ops, sizeof(smm->sm));

	r = sm_ll_new_metadata(&smm->ll, tm);
	if (r)
		return r;

	if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
		nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
	r = sm_ll_extend(&smm->ll, nr_blocks);
	if (r)
		return r;

	memcpy(&smm->sm, &ops, sizeof(smm->sm));

	/*
         * Now we need to update the newly created data structures with the
         * allocated blocks that they were built from.
         */
	for (i = superblock; !r && i < smm->begin; i++)
		r = add_bop(smm, BOP_INC, i);

	if (r)
		return r;

	r = apply_bops(smm);
	if (r) {
		DMERR("%s: apply_bops failed", __func__);
		return r;
	}

	return sm_metadata_commit(sm);
}

Contributors
Person Tokens Prop Commits CommitProp
joe thornber joe thornber 218 95.61% 5 83.33%
mike snitzer mike snitzer 10 4.39% 1 16.67%
Total 228 100.00% 6 100.00%



int dm_sm_metadata_open(struct dm_space_map *sm,
			struct dm_transaction_manager *tm,
			void *root_le, size_t len)
{
	int r;
	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);

	r = sm_ll_open_metadata(&smm->ll, tm, root_le, len);
	if (r)
		return r;

	smm->begin = 0;
	smm->recursion_count = 0;
	smm->allocated_this_transaction = 0;
	brb_init(&smm->uncommitted);
	threshold_init(&smm->threshold);

	memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
	return 0;
}
Contributors
Person Tokens Prop Commits CommitProp
joe thornber joe thornber 120 100.00% 3 100.00%
Total 120 100.00% 3 100.00%

Overall Contributors
Person Tokens Prop Commits CommitProp
joe thornber joe thornber 3334 99.17% 12 75.00%
mike snitzer mike snitzer 22 0.65% 3 18.75%
dan carpenter dan carpenter 6 0.18% 1 6.25%
Total 3362 100.00% 16 100.00%
  Directory: drivers/md/persistent-data

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
	Person	Tokens	Prop	Commits	CommitProp
joe thornber	joe thornber	23	100.00%	1	100.00%
	Total	23	100.00%	1	100.00%
cregit-Linux how code gets into the kernel

Release 4.7 drivers/md/persistent-data/dm-space-map-metadata.c

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