dm-table.c 38.5 KB
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/*
 * Copyright (C) 2001 Sistina Software (UK) Limited.
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 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
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 *
 * This file is released under the GPL.
 */

#include "dm.h"

#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/blkdev.h>
#include <linux/namei.h>
#include <linux/ctype.h>
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#include <linux/string.h>
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#include <linux/slab.h>
#include <linux/interrupt.h>
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#include <linux/mutex.h>
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#include <linux/delay.h>
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#include <linux/atomic.h>
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#define DM_MSG_PREFIX "table"

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#define MAX_DEPTH 16
#define NODE_SIZE L1_CACHE_BYTES
#define KEYS_PER_NODE (NODE_SIZE / sizeof(sector_t))
#define CHILDREN_PER_NODE (KEYS_PER_NODE + 1)

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/*
 * The table has always exactly one reference from either mapped_device->map
 * or hash_cell->new_map. This reference is not counted in table->holders.
 * A pair of dm_create_table/dm_destroy_table functions is used for table
 * creation/destruction.
 *
 * Temporary references from the other code increase table->holders. A pair
 * of dm_table_get/dm_table_put functions is used to manipulate it.
 *
 * When the table is about to be destroyed, we wait for table->holders to
 * drop to zero.
 */

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struct dm_table {
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	struct mapped_device *md;
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	atomic_t holders;
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	unsigned type;
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	/* btree table */
	unsigned int depth;
	unsigned int counts[MAX_DEPTH];	/* in nodes */
	sector_t *index[MAX_DEPTH];

	unsigned int num_targets;
	unsigned int num_allocated;
	sector_t *highs;
	struct dm_target *targets;

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	struct target_type *immutable_target_type;
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	unsigned integrity_supported:1;
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	unsigned singleton:1;
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	/*
	 * Indicates the rw permissions for the new logical
	 * device.  This should be a combination of FMODE_READ
	 * and FMODE_WRITE.
	 */
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	fmode_t mode;
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	/* a list of devices used by this table */
	struct list_head devices;

	/* events get handed up using this callback */
	void (*event_fn)(void *);
	void *event_context;
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	struct dm_md_mempools *mempools;
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	struct list_head target_callbacks;
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};

/*
 * Similar to ceiling(log_size(n))
 */
static unsigned int int_log(unsigned int n, unsigned int base)
{
	int result = 0;

	while (n > 1) {
		n = dm_div_up(n, base);
		result++;
	}

	return result;
}

/*
 * Calculate the index of the child node of the n'th node k'th key.
 */
static inline unsigned int get_child(unsigned int n, unsigned int k)
{
	return (n * CHILDREN_PER_NODE) + k;
}

/*
 * Return the n'th node of level l from table t.
 */
static inline sector_t *get_node(struct dm_table *t,
				 unsigned int l, unsigned int n)
{
	return t->index[l] + (n * KEYS_PER_NODE);
}

/*
 * Return the highest key that you could lookup from the n'th
 * node on level l of the btree.
 */
static sector_t high(struct dm_table *t, unsigned int l, unsigned int n)
{
	for (; l < t->depth - 1; l++)
		n = get_child(n, CHILDREN_PER_NODE - 1);

	if (n >= t->counts[l])
		return (sector_t) - 1;

	return get_node(t, l, n)[KEYS_PER_NODE - 1];
}

/*
 * Fills in a level of the btree based on the highs of the level
 * below it.
 */
static int setup_btree_index(unsigned int l, struct dm_table *t)
{
	unsigned int n, k;
	sector_t *node;

	for (n = 0U; n < t->counts[l]; n++) {
		node = get_node(t, l, n);

		for (k = 0U; k < KEYS_PER_NODE; k++)
			node[k] = high(t, l + 1, get_child(n, k));
	}

	return 0;
}

void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size)
{
	unsigned long size;
	void *addr;

	/*
	 * Check that we're not going to overflow.
	 */
	if (nmemb > (ULONG_MAX / elem_size))
		return NULL;

	size = nmemb * elem_size;
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	addr = vzalloc(size);
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	return addr;
}
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EXPORT_SYMBOL(dm_vcalloc);
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/*
 * highs, and targets are managed as dynamic arrays during a
 * table load.
 */
static int alloc_targets(struct dm_table *t, unsigned int num)
{
	sector_t *n_highs;
	struct dm_target *n_targets;
	int n = t->num_targets;

	/*
	 * Allocate both the target array and offset array at once.
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	 * Append an empty entry to catch sectors beyond the end of
	 * the device.
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	 */
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	n_highs = (sector_t *) dm_vcalloc(num + 1, sizeof(struct dm_target) +
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					  sizeof(sector_t));
	if (!n_highs)
		return -ENOMEM;

	n_targets = (struct dm_target *) (n_highs + num);

	if (n) {
		memcpy(n_highs, t->highs, sizeof(*n_highs) * n);
		memcpy(n_targets, t->targets, sizeof(*n_targets) * n);
	}

	memset(n_highs + n, -1, sizeof(*n_highs) * (num - n));
	vfree(t->highs);

	t->num_allocated = num;
	t->highs = n_highs;
	t->targets = n_targets;

	return 0;
}

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int dm_table_create(struct dm_table **result, fmode_t mode,
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		    unsigned num_targets, struct mapped_device *md)
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{
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	struct dm_table *t = kzalloc(sizeof(*t), GFP_KERNEL);
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	if (!t)
		return -ENOMEM;

	INIT_LIST_HEAD(&t->devices);
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	INIT_LIST_HEAD(&t->target_callbacks);
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	atomic_set(&t->holders, 0);
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	if (!num_targets)
		num_targets = KEYS_PER_NODE;

	num_targets = dm_round_up(num_targets, KEYS_PER_NODE);

	if (alloc_targets(t, num_targets)) {
		kfree(t);
		return -ENOMEM;
	}

	t->mode = mode;
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	t->md = md;
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	*result = t;
	return 0;
}

static void free_devices(struct list_head *devices)
{
	struct list_head *tmp, *next;

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	list_for_each_safe(tmp, next, devices) {
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		struct dm_dev_internal *dd =
		    list_entry(tmp, struct dm_dev_internal, list);
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		DMWARN("dm_table_destroy: dm_put_device call missing for %s",
		       dd->dm_dev.name);
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		kfree(dd);
	}
}

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void dm_table_destroy(struct dm_table *t)
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{
	unsigned int i;

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	if (!t)
		return;

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	while (atomic_read(&t->holders))
		msleep(1);
	smp_mb();

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	/* free the indexes */
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	if (t->depth >= 2)
		vfree(t->index[t->depth - 2]);

	/* free the targets */
	for (i = 0; i < t->num_targets; i++) {
		struct dm_target *tgt = t->targets + i;

		if (tgt->type->dtr)
			tgt->type->dtr(tgt);

		dm_put_target_type(tgt->type);
	}

	vfree(t->highs);

	/* free the device list */
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	free_devices(&t->devices);
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	dm_free_md_mempools(t->mempools);

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	kfree(t);
}

void dm_table_get(struct dm_table *t)
{
	atomic_inc(&t->holders);
}
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EXPORT_SYMBOL(dm_table_get);
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void dm_table_put(struct dm_table *t)
{
	if (!t)
		return;

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	smp_mb__before_atomic_dec();
	atomic_dec(&t->holders);
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}
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EXPORT_SYMBOL(dm_table_put);
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/*
 * Checks to see if we need to extend highs or targets.
 */
static inline int check_space(struct dm_table *t)
{
	if (t->num_targets >= t->num_allocated)
		return alloc_targets(t, t->num_allocated * 2);

	return 0;
}

/*
 * See if we've already got a device in the list.
 */
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static struct dm_dev_internal *find_device(struct list_head *l, dev_t dev)
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{
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	struct dm_dev_internal *dd;
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	list_for_each_entry (dd, l, list)
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		if (dd->dm_dev.bdev->bd_dev == dev)
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			return dd;

	return NULL;
}

/*
 * Open a device so we can use it as a map destination.
 */
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static int open_dev(struct dm_dev_internal *d, dev_t dev,
		    struct mapped_device *md)
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{
	static char *_claim_ptr = "I belong to device-mapper";
	struct block_device *bdev;

	int r;

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	BUG_ON(d->dm_dev.bdev);
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	bdev = blkdev_get_by_dev(dev, d->dm_dev.mode | FMODE_EXCL, _claim_ptr);
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	if (IS_ERR(bdev))
		return PTR_ERR(bdev);
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	r = bd_link_disk_holder(bdev, dm_disk(md));
	if (r) {
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		blkdev_put(bdev, d->dm_dev.mode | FMODE_EXCL);
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		return r;
	}

	d->dm_dev.bdev = bdev;
	return 0;
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}

/*
 * Close a device that we've been using.
 */
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static void close_dev(struct dm_dev_internal *d, struct mapped_device *md)
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{
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	if (!d->dm_dev.bdev)
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		return;

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	bd_unlink_disk_holder(d->dm_dev.bdev, dm_disk(md));
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	blkdev_put(d->dm_dev.bdev, d->dm_dev.mode | FMODE_EXCL);
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	d->dm_dev.bdev = NULL;
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}

/*
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 * If possible, this checks an area of a destination device is invalid.
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 */
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static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
				  sector_t start, sector_t len, void *data)
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{
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	struct request_queue *q;
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	struct queue_limits *limits = data;
	struct block_device *bdev = dev->bdev;
	sector_t dev_size =
		i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
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	unsigned short logical_block_size_sectors =
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		limits->logical_block_size >> SECTOR_SHIFT;
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	char b[BDEVNAME_SIZE];
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	/*
	 * Some devices exist without request functions,
	 * such as loop devices not yet bound to backing files.
	 * Forbid the use of such devices.
	 */
	q = bdev_get_queue(bdev);
	if (!q || !q->make_request_fn) {
		DMWARN("%s: %s is not yet initialised: "
		       "start=%llu, len=%llu, dev_size=%llu",
		       dm_device_name(ti->table->md), bdevname(bdev, b),
		       (unsigned long long)start,
		       (unsigned long long)len,
		       (unsigned long long)dev_size);
		return 1;
	}

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	if (!dev_size)
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		return 0;
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	if ((start >= dev_size) || (start + len > dev_size)) {
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		DMWARN("%s: %s too small for target: "
		       "start=%llu, len=%llu, dev_size=%llu",
		       dm_device_name(ti->table->md), bdevname(bdev, b),
		       (unsigned long long)start,
		       (unsigned long long)len,
		       (unsigned long long)dev_size);
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		return 1;
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	}

	if (logical_block_size_sectors <= 1)
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		return 0;
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	if (start & (logical_block_size_sectors - 1)) {
		DMWARN("%s: start=%llu not aligned to h/w "
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		       "logical block size %u of %s",
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		       dm_device_name(ti->table->md),
		       (unsigned long long)start,
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		       limits->logical_block_size, bdevname(bdev, b));
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		return 1;
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	}

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	if (len & (logical_block_size_sectors - 1)) {
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		DMWARN("%s: len=%llu not aligned to h/w "
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		       "logical block size %u of %s",
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		       dm_device_name(ti->table->md),
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		       (unsigned long long)len,
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		       limits->logical_block_size, bdevname(bdev, b));
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		return 1;
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	}

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	return 0;
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}

/*
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 * This upgrades the mode on an already open dm_dev, being
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 * careful to leave things as they were if we fail to reopen the
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 * device and not to touch the existing bdev field in case
 * it is accessed concurrently inside dm_table_any_congested().
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 */
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static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode,
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			struct mapped_device *md)
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{
	int r;
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	struct dm_dev_internal dd_new, dd_old;
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	dd_new = dd_old = *dd;

	dd_new.dm_dev.mode |= new_mode;
	dd_new.dm_dev.bdev = NULL;

	r = open_dev(&dd_new, dd->dm_dev.bdev->bd_dev, md);
	if (r)
		return r;
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	dd->dm_dev.mode |= new_mode;
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	close_dev(&dd_old, md);
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	return 0;
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}

/*
 * Add a device to the list, or just increment the usage count if
 * it's already present.
 */
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int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
		  struct dm_dev **result)
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{
	int r;
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	dev_t uninitialized_var(dev);
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	struct dm_dev_internal *dd;
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	unsigned int major, minor;
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	struct dm_table *t = ti->table;
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	char dummy;
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	BUG_ON(!t);
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	if (sscanf(path, "%u:%u%c", &major, &minor, &dummy) == 2) {
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		/* Extract the major/minor numbers */
		dev = MKDEV(major, minor);
		if (MAJOR(dev) != major || MINOR(dev) != minor)
			return -EOVERFLOW;
	} else {
		/* convert the path to a device */
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		struct block_device *bdev = lookup_bdev(path);

		if (IS_ERR(bdev))
			return PTR_ERR(bdev);
		dev = bdev->bd_dev;
		bdput(bdev);
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	}

	dd = find_device(&t->devices, dev);
	if (!dd) {
		dd = kmalloc(sizeof(*dd), GFP_KERNEL);
		if (!dd)
			return -ENOMEM;

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		dd->dm_dev.mode = mode;
		dd->dm_dev.bdev = NULL;
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		if ((r = open_dev(dd, dev, t->md))) {
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			kfree(dd);
			return r;
		}

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		format_dev_t(dd->dm_dev.name, dev);
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		atomic_set(&dd->count, 0);
		list_add(&dd->list, &t->devices);

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	} else if (dd->dm_dev.mode != (mode | dd->dm_dev.mode)) {
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		r = upgrade_mode(dd, mode, t->md);
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		if (r)
			return r;
	}
	atomic_inc(&dd->count);

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	*result = &dd->dm_dev;
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	return 0;
}
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EXPORT_SYMBOL(dm_get_device);
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int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
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			 sector_t start, sector_t len, void *data)
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{
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	struct queue_limits *limits = data;
	struct block_device *bdev = dev->bdev;
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	struct request_queue *q = bdev_get_queue(bdev);
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	char b[BDEVNAME_SIZE];

	if (unlikely(!q)) {
		DMWARN("%s: Cannot set limits for nonexistent device %s",
		       dm_device_name(ti->table->md), bdevname(bdev, b));
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		return 0;
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	}
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	if (bdev_stack_limits(limits, bdev, start) < 0)
		DMWARN("%s: adding target device %s caused an alignment inconsistency: "
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		       "physical_block_size=%u, logical_block_size=%u, "
		       "alignment_offset=%u, start=%llu",
		       dm_device_name(ti->table->md), bdevname(bdev, b),
		       q->limits.physical_block_size,
		       q->limits.logical_block_size,
		       q->limits.alignment_offset,
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		       (unsigned long long) start << SECTOR_SHIFT);
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	/*
	 * Check if merge fn is supported.
	 * If not we'll force DM to use PAGE_SIZE or
	 * smaller I/O, just to be safe.
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	 */
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	if (dm_queue_merge_is_compulsory(q) && !ti->type->merge)
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		blk_limits_max_hw_sectors(limits,
					  (unsigned int) (PAGE_SIZE >> 9));
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	return 0;
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}
EXPORT_SYMBOL_GPL(dm_set_device_limits);
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/*
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 * Decrement a device's use count and remove it if necessary.
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 */
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void dm_put_device(struct dm_target *ti, struct dm_dev *d)
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{
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	struct dm_dev_internal *dd = container_of(d, struct dm_dev_internal,
						  dm_dev);

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	if (atomic_dec_and_test(&dd->count)) {
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		close_dev(dd, ti->table->md);
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		list_del(&dd->list);
		kfree(dd);
	}
}
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EXPORT_SYMBOL(dm_put_device);
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/*
 * Checks to see if the target joins onto the end of the table.
 */
static int adjoin(struct dm_table *table, struct dm_target *ti)
{
	struct dm_target *prev;

	if (!table->num_targets)
		return !ti->begin;

	prev = &table->targets[table->num_targets - 1];
	return (ti->begin == (prev->begin + prev->len));
}

/*
 * Used to dynamically allocate the arg array.
 */
static char **realloc_argv(unsigned *array_size, char **old_argv)
{
	char **argv;
	unsigned new_size;

	new_size = *array_size ? *array_size * 2 : 64;
	argv = kmalloc(new_size * sizeof(*argv), GFP_KERNEL);
	if (argv) {
		memcpy(argv, old_argv, *array_size * sizeof(*argv));
		*array_size = new_size;
	}

	kfree(old_argv);
	return argv;
}

/*
 * Destructively splits up the argument list to pass to ctr.
 */
int dm_split_args(int *argc, char ***argvp, char *input)
{
	char *start, *end = input, *out, **argv = NULL;
	unsigned array_size = 0;

	*argc = 0;
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	if (!input) {
		*argvp = NULL;
		return 0;
	}

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	argv = realloc_argv(&array_size, argv);
	if (!argv)
		return -ENOMEM;

	while (1) {
		/* Skip whitespace */
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		start = skip_spaces(end);
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		if (!*start)
			break;	/* success, we hit the end */

		/* 'out' is used to remove any back-quotes */
		end = out = start;
		while (*end) {
			/* Everything apart from '\0' can be quoted */
			if (*end == '\\' && *(end + 1)) {
				*out++ = *(end + 1);
				end += 2;
				continue;
			}

			if (isspace(*end))
				break;	/* end of token */

			*out++ = *end++;
		}

		/* have we already filled the array ? */
		if ((*argc + 1) > array_size) {
			argv = realloc_argv(&array_size, argv);
			if (!argv)
				return -ENOMEM;
		}

		/* we know this is whitespace */
		if (*end)
			end++;

		/* terminate the string and put it in the array */
		*out = '\0';
		argv[*argc] = start;
		(*argc)++;
	}

	*argvp = argv;
	return 0;
}

663 664 665 666 667 668 669
/*
 * Impose necessary and sufficient conditions on a devices's table such
 * that any incoming bio which respects its logical_block_size can be
 * processed successfully.  If it falls across the boundary between
 * two or more targets, the size of each piece it gets split into must
 * be compatible with the logical_block_size of the target processing it.
 */
670 671
static int validate_hardware_logical_block_alignment(struct dm_table *table,
						 struct queue_limits *limits)
672 673 674 675 676 677
{
	/*
	 * This function uses arithmetic modulo the logical_block_size
	 * (in units of 512-byte sectors).
	 */
	unsigned short device_logical_block_size_sects =
678
		limits->logical_block_size >> SECTOR_SHIFT;
679 680 681 682 683 684 685 686 687 688 689 690 691

	/*
	 * Offset of the start of the next table entry, mod logical_block_size.
	 */
	unsigned short next_target_start = 0;

	/*
	 * Given an aligned bio that extends beyond the end of a
	 * target, how many sectors must the next target handle?
	 */
	unsigned short remaining = 0;

	struct dm_target *uninitialized_var(ti);
692
	struct queue_limits ti_limits;
693 694 695 696 697 698 699 700
	unsigned i = 0;

	/*
	 * Check each entry in the table in turn.
	 */
	while (i < dm_table_get_num_targets(table)) {
		ti = dm_table_get_target(table, i++);

701
		blk_set_stacking_limits(&ti_limits);
702 703 704 705 706 707

		/* combine all target devices' limits */
		if (ti->type->iterate_devices)
			ti->type->iterate_devices(ti, dm_set_device_limits,
						  &ti_limits);

708 709 710 711 712
		/*
		 * If the remaining sectors fall entirely within this
		 * table entry are they compatible with its logical_block_size?
		 */
		if (remaining < ti->len &&
713
		    remaining & ((ti_limits.logical_block_size >>
714 715 716 717 718 719 720 721 722 723 724 725
				  SECTOR_SHIFT) - 1))
			break;	/* Error */

		next_target_start =
		    (unsigned short) ((next_target_start + ti->len) &
				      (device_logical_block_size_sects - 1));
		remaining = next_target_start ?
		    device_logical_block_size_sects - next_target_start : 0;
	}

	if (remaining) {
		DMWARN("%s: table line %u (start sect %llu len %llu) "
726
		       "not aligned to h/w logical block size %u",
727 728 729
		       dm_device_name(table->md), i,
		       (unsigned long long) ti->begin,
		       (unsigned long long) ti->len,
730
		       limits->logical_block_size);
731 732 733 734 735 736
		return -EINVAL;
	}

	return 0;
}

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int dm_table_add_target(struct dm_table *t, const char *type,
			sector_t start, sector_t len, char *params)
{
	int r = -EINVAL, argc;
	char **argv;
	struct dm_target *tgt;

744 745 746 747 748 749
	if (t->singleton) {
		DMERR("%s: target type %s must appear alone in table",
		      dm_device_name(t->md), t->targets->type->name);
		return -EINVAL;
	}

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	if ((r = check_space(t)))
		return r;

	tgt = t->targets + t->num_targets;
	memset(tgt, 0, sizeof(*tgt));

	if (!len) {
757
		DMERR("%s: zero-length target", dm_device_name(t->md));
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		return -EINVAL;
	}

	tgt->type = dm_get_target_type(type);
	if (!tgt->type) {
763 764
		DMERR("%s: %s: unknown target type", dm_device_name(t->md),
		      type);
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		return -EINVAL;
	}

768 769 770 771 772 773 774 775 776
	if (dm_target_needs_singleton(tgt->type)) {
		if (t->num_targets) {
			DMERR("%s: target type %s must appear alone in table",
			      dm_device_name(t->md), type);
			return -EINVAL;
		}
		t->singleton = 1;
	}

777 778 779 780 781 782
	if (dm_target_always_writeable(tgt->type) && !(t->mode & FMODE_WRITE)) {
		DMERR("%s: target type %s may not be included in read-only tables",
		      dm_device_name(t->md), type);
		return -EINVAL;
	}

783 784 785 786 787 788 789 790 791 792 793 794 795 796 797
	if (t->immutable_target_type) {
		if (t->immutable_target_type != tgt->type) {
			DMERR("%s: immutable target type %s cannot be mixed with other target types",
			      dm_device_name(t->md), t->immutable_target_type->name);
			return -EINVAL;
		}
	} else if (dm_target_is_immutable(tgt->type)) {
		if (t->num_targets) {
			DMERR("%s: immutable target type %s cannot be mixed with other target types",
			      dm_device_name(t->md), tgt->type->name);
			return -EINVAL;
		}
		t->immutable_target_type = tgt->type;
	}

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	tgt->table = t;
	tgt->begin = start;
	tgt->len = len;
	tgt->error = "Unknown error";

	/*
	 * Does this target adjoin the previous one ?
	 */
	if (!adjoin(t, tgt)) {
		tgt->error = "Gap in table";
		r = -EINVAL;
		goto bad;
	}

	r = dm_split_args(&argc, &argv, params);
	if (r) {
		tgt->error = "couldn't split parameters (insufficient memory)";
		goto bad;
	}

	r = tgt->type->ctr(tgt, argc, argv);
	kfree(argv);
	if (r)
		goto bad;

	t->highs[t->num_targets++] = tgt->begin + tgt->len - 1;

825 826
	if (!tgt->num_discard_bios && tgt->discards_supported)
		DMWARN("%s: %s: ignoring discards_supported because num_discard_bios is zero.",
827
		       dm_device_name(t->md), type);
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	return 0;

 bad:
832
	DMERR("%s: %s: %s", dm_device_name(t->md), type, tgt->error);
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	dm_put_target_type(tgt->type);
	return r;
}

837 838 839 840 841 842 843
/*
 * Target argument parsing helpers.
 */
static int validate_next_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
			     unsigned *value, char **error, unsigned grouped)
{
	const char *arg_str = dm_shift_arg(arg_set);
844
	char dummy;
845 846

	if (!arg_str ||
847
	    (sscanf(arg_str, "%u%c", value, &dummy) != 1) ||
848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894
	    (*value < arg->min) ||
	    (*value > arg->max) ||
	    (grouped && arg_set->argc < *value)) {
		*error = arg->error;
		return -EINVAL;
	}

	return 0;
}

int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
		unsigned *value, char **error)
{
	return validate_next_arg(arg, arg_set, value, error, 0);
}
EXPORT_SYMBOL(dm_read_arg);

int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
		      unsigned *value, char **error)
{
	return validate_next_arg(arg, arg_set, value, error, 1);
}
EXPORT_SYMBOL(dm_read_arg_group);

const char *dm_shift_arg(struct dm_arg_set *as)
{
	char *r;

	if (as->argc) {
		as->argc--;
		r = *as->argv;
		as->argv++;
		return r;
	}

	return NULL;
}
EXPORT_SYMBOL(dm_shift_arg);

void dm_consume_args(struct dm_arg_set *as, unsigned num_args)
{
	BUG_ON(as->argc < num_args);
	as->argc -= num_args;
	as->argv += num_args;
}
EXPORT_SYMBOL(dm_consume_args);

895
static int dm_table_set_type(struct dm_table *t)
896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955
{
	unsigned i;
	unsigned bio_based = 0, request_based = 0;
	struct dm_target *tgt;
	struct dm_dev_internal *dd;
	struct list_head *devices;

	for (i = 0; i < t->num_targets; i++) {
		tgt = t->targets + i;
		if (dm_target_request_based(tgt))
			request_based = 1;
		else
			bio_based = 1;

		if (bio_based && request_based) {
			DMWARN("Inconsistent table: different target types"
			       " can't be mixed up");
			return -EINVAL;
		}
	}

	if (bio_based) {
		/* We must use this table as bio-based */
		t->type = DM_TYPE_BIO_BASED;
		return 0;
	}

	BUG_ON(!request_based); /* No targets in this table */

	/* Non-request-stackable devices can't be used for request-based dm */
	devices = dm_table_get_devices(t);
	list_for_each_entry(dd, devices, list) {
		if (!blk_queue_stackable(bdev_get_queue(dd->dm_dev.bdev))) {
			DMWARN("table load rejected: including"
			       " non-request-stackable devices");
			return -EINVAL;
		}
	}

	/*
	 * Request-based dm supports only tables that have a single target now.
	 * To support multiple targets, request splitting support is needed,
	 * and that needs lots of changes in the block-layer.
	 * (e.g. request completion process for partial completion.)
	 */
	if (t->num_targets > 1) {
		DMWARN("Request-based dm doesn't support multiple targets yet");
		return -EINVAL;
	}

	t->type = DM_TYPE_REQUEST_BASED;

	return 0;
}

unsigned dm_table_get_type(struct dm_table *t)
{
	return t->type;
}

956 957 958 959 960
struct target_type *dm_table_get_immutable_target_type(struct dm_table *t)
{
	return t->immutable_target_type;
}

961 962 963 964 965 966 967 968
bool dm_table_request_based(struct dm_table *t)
{
	return dm_table_get_type(t) == DM_TYPE_REQUEST_BASED;
}

int dm_table_alloc_md_mempools(struct dm_table *t)
{
	unsigned type = dm_table_get_type(t);
969 970 971
	unsigned per_bio_data_size = 0;
	struct dm_target *tgt;
	unsigned i;
972 973 974 975 976 977

	if (unlikely(type == DM_TYPE_NONE)) {
		DMWARN("no table type is set, can't allocate mempools");
		return -EINVAL;
	}

978 979 980 981 982 983 984
	if (type == DM_TYPE_BIO_BASED)
		for (i = 0; i < t->num_targets; i++) {
			tgt = t->targets + i;
			per_bio_data_size = max(per_bio_data_size, tgt->per_bio_data_size);
		}

	t->mempools = dm_alloc_md_mempools(type, t->integrity_supported, per_bio_data_size);
985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001
	if (!t->mempools)
		return -ENOMEM;

	return 0;
}

void dm_table_free_md_mempools(struct dm_table *t)
{
	dm_free_md_mempools(t->mempools);
	t->mempools = NULL;
}

struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t)
{
	return t->mempools;
}

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static int setup_indexes(struct dm_table *t)
{
	int i;
	unsigned int total = 0;
	sector_t *indexes;

	/* allocate the space for *all* the indexes */
	for (i = t->depth - 2; i >= 0; i--) {
		t->counts[i] = dm_div_up(t->counts[i + 1], CHILDREN_PER_NODE);
		total += t->counts[i];
	}

	indexes = (sector_t *) dm_vcalloc(total, (unsigned long) NODE_SIZE);
	if (!indexes)
		return -ENOMEM;

	/* set up internal nodes, bottom-up */
1019
	for (i = t->depth - 2; i >= 0; i--) {
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		t->index[i] = indexes;
		indexes += (KEYS_PER_NODE * t->counts[i]);
		setup_btree_index(i, t);
	}

	return 0;
}

/*
 * Builds the btree to index the map.
 */
1031
static int dm_table_build_index(struct dm_table *t)
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{
	int r = 0;
	unsigned int leaf_nodes;

	/* how many indexes will the btree have ? */
	leaf_nodes = dm_div_up(t->num_targets, KEYS_PER_NODE);
	t->depth = 1 + int_log(leaf_nodes, CHILDREN_PER_NODE);

	/* leaf layer has already been set up */
	t->counts[t->depth - 1] = leaf_nodes;
	t->index[t->depth - 1] = t->highs;

	if (t->depth >= 2)
		r = setup_indexes(t);

	return r;
}

1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086
/*
 * Get a disk whose integrity profile reflects the table's profile.
 * If %match_all is true, all devices' profiles must match.
 * If %match_all is false, all devices must at least have an
 * allocated integrity profile; but uninitialized is ok.
 * Returns NULL if integrity support was inconsistent or unavailable.
 */
static struct gendisk * dm_table_get_integrity_disk(struct dm_table *t,
						    bool match_all)
{
	struct list_head *devices = dm_table_get_devices(t);
	struct dm_dev_internal *dd = NULL;
	struct gendisk *prev_disk = NULL, *template_disk = NULL;

	list_for_each_entry(dd, devices, list) {
		template_disk = dd->dm_dev.bdev->bd_disk;
		if (!blk_get_integrity(template_disk))
			goto no_integrity;
		if (!match_all && !blk_integrity_is_initialized(template_disk))
			continue; /* skip uninitialized profiles */
		else if (prev_disk &&
			 blk_integrity_compare(prev_disk, template_disk) < 0)
			goto no_integrity;
		prev_disk = template_disk;
	}

	return template_disk;

no_integrity:
	if (prev_disk)
		DMWARN("%s: integrity not set: %s and %s profile mismatch",
		       dm_device_name(t->md),
		       prev_disk->disk_name,
		       template_disk->disk_name);
	return NULL;
}

1087 1088
/*
 * Register the mapped device for blk_integrity support if
1089 1090 1091 1092 1093 1094 1095
 * the underlying devices have an integrity profile.  But all devices
 * may not have matching profiles (checking all devices isn't reliable
 * during table load because this table may use other DM device(s) which
 * must be resumed before they will have an initialized integity profile).
 * Stacked DM devices force a 2 stage integrity profile validation:
 * 1 - during load, validate all initialized integrity profiles match
 * 2 - during resume, validate all integrity profiles match
1096 1097 1098
 */
static int dm_table_prealloc_integrity(struct dm_table *t, struct mapped_device *md)
{
1099
	struct gendisk *template_disk = NULL;
1100

1101 1102 1103
	template_disk = dm_table_get_integrity_disk(t, false);
	if (!template_disk)
		return 0;
1104

1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124
	if (!blk_integrity_is_initialized(dm_disk(md))) {
		t->integrity_supported = 1;
		return blk_integrity_register(dm_disk(md), NULL);
	}

	/*
	 * If DM device already has an initalized integrity
	 * profile the new profile should not conflict.
	 */
	if (blk_integrity_is_initialized(template_disk) &&
	    blk_integrity_compare(dm_disk(md), template_disk) < 0) {
		DMWARN("%s: conflict with existing integrity profile: "
		       "%s profile mismatch",
		       dm_device_name(t->md),
		       template_disk->disk_name);
		return 1;
	}

	/* Preserve existing initialized integrity profile */
	t->integrity_supported = 1;
1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160
	return 0;
}

/*
 * Prepares the table for use by building the indices,
 * setting the type, and allocating mempools.
 */
int dm_table_complete(struct dm_table *t)
{
	int r;

	r = dm_table_set_type(t);
	if (r) {
		DMERR("unable to set table type");
		return r;
	}

	r = dm_table_build_index(t);
	if (r) {
		DMERR("unable to build btrees");
		return r;
	}

	r = dm_table_prealloc_integrity(t, t->md);
	if (r) {
		DMERR("could not register integrity profile.");
		return r;
	}

	r = dm_table_alloc_md_mempools(t);
	if (r)
		DMERR("unable to allocate mempools");

	return r;
}

1161
static DEFINE_MUTEX(_event_lock);
L
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void dm_table_event_callback(struct dm_table *t,
			     void (*fn)(void *), void *context)
{
1165
	mutex_lock(&_event_lock);
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1166 1167
	t->event_fn = fn;
	t->event_context = context;
1168
	mutex_unlock(&_event_lock);
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1169 1170 1171 1172 1173 1174 1175 1176 1177 1178
}

void dm_table_event(struct dm_table *t)
{
	/*
	 * You can no longer call dm_table_event() from interrupt
	 * context, use a bottom half instead.
	 */
	BUG_ON(in_interrupt());

1179
	mutex_lock(&_event_lock);
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1180 1181
	if (t->event_fn)
		t->event_fn(t->event_context);
1182
	mutex_unlock(&_event_lock);
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1183
}
1184
EXPORT_SYMBOL(dm_table_event);
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sector_t dm_table_get_size(struct dm_table *t)
{
	return t->num_targets ? (t->highs[t->num_targets - 1] + 1) : 0;
}
1190
EXPORT_SYMBOL(dm_table_get_size);
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struct dm_target *dm_table_get_target(struct dm_table *t, unsigned int index)
{
1194
	if (index >= t->num_targets)
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		return NULL;

	return t->targets + index;
}

/*
 * Search the btree for the correct target.
1202 1203 1204
 *
 * Caller should check returned pointer with dm_target_is_valid()
 * to trap I/O beyond end of device.
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 */
struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector)
{
	unsigned int l, n = 0, k = 0;
	sector_t *node;

	for (l = 0; l < t->depth; l++) {
		n = get_child(n, k);
		node = get_node(t, l, n);

		for (k = 0; k < KEYS_PER_NODE; k++)
			if (node[k] >= sector)
				break;
	}

	return &t->targets[(KEYS_PER_NODE * n) + k];
}

1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257
static int count_device(struct dm_target *ti, struct dm_dev *dev,
			sector_t start, sector_t len, void *data)
{
	unsigned *num_devices = data;

	(*num_devices)++;

	return 0;
}

/*
 * Check whether a table has no data devices attached using each
 * target's iterate_devices method.
 * Returns false if the result is unknown because a target doesn't
 * support iterate_devices.
 */
bool dm_table_has_no_data_devices(struct dm_table *table)
{
	struct dm_target *uninitialized_var(ti);
	unsigned i = 0, num_devices = 0;

	while (i < dm_table_get_num_targets(table)) {
		ti = dm_table_get_target(table, i++);

		if (!ti->type->iterate_devices)
			return false;

		ti->type->iterate_devices(ti, count_device, &num_devices);
		if (num_devices)
			return false;
	}

	return true;
}

1258 1259 1260 1261 1262 1263 1264 1265 1266 1267
/*
 * Establish the new table's queue_limits and validate them.
 */
int dm_calculate_queue_limits(struct dm_table *table,
			      struct queue_limits *limits)
{
	struct dm_target *uninitialized_var(ti);
	struct queue_limits ti_limits;
	unsigned i = 0;

1268
	blk_set_stacking_limits(limits);
1269 1270

	while (i < dm_table_get_num_targets(table)) {
1271
		blk_set_stacking_limits(&ti_limits);
1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283

		ti = dm_table_get_target(table, i++);

		if (!ti->type->iterate_devices)
			goto combine_limits;

		/*
		 * Combine queue limits of all the devices this target uses.
		 */
		ti->type->iterate_devices(ti, dm_set_device_limits,
					  &ti_limits);

1284 1285 1286 1287
		/* Set I/O hints portion of queue limits */
		if (ti->type->io_hints)
			ti->type->io_hints(ti, &ti_limits);

1288 1289 1290 1291
		/*
		 * Check each device area is consistent with the target's
		 * overall queue limits.
		 */
1292 1293
		if (ti->type->iterate_devices(ti, device_area_is_invalid,
					      &ti_limits))
1294 1295 1296 1297 1298 1299 1300 1301
			return -EINVAL;

combine_limits:
		/*
		 * Merge this target's queue limits into the overall limits
		 * for the table.
		 */
		if (blk_stack_limits(limits, &ti_limits, 0) < 0)
1302
			DMWARN("%s: adding target device "
1303
			       "(start sect %llu len %llu) "
1304
			       "caused an alignment inconsistency",
1305 1306 1307 1308 1309 1310 1311 1312
			       dm_device_name(table->md),
			       (unsigned long long) ti->begin,
			       (unsigned long long) ti->len);
	}

	return validate_hardware_logical_block_alignment(table, limits);
}

1313 1314
/*
 * Set the integrity profile for this device if all devices used have
1315 1316 1317 1318
 * matching profiles.  We're quite deep in the resume path but still
 * don't know if all devices (particularly DM devices this device
 * may be stacked on) have matching profiles.  Even if the profiles
 * don't match we have no way to fail (to resume) at this point.
1319 1320 1321
 */
static void dm_table_set_integrity(struct dm_table *t)
{
1322
	struct gendisk *template_disk = NULL;
1323 1324 1325 1326

	if (!blk_get_integrity(dm_disk(t->md)))
		return;

1327
	template_disk = dm_table_get_integrity_disk(t, true);
1328 1329 1330 1331
	if (template_disk)
		blk_integrity_register(dm_disk(t->md),
				       blk_get_integrity(template_disk));
	else if (blk_integrity_is_initialized(dm_disk(t->md)))
1332 1333
		DMWARN("%s: device no longer has a valid integrity profile",
		       dm_device_name(t->md));
1334 1335 1336
	else
		DMWARN("%s: unable to establish an integrity profile",
		       dm_device_name(t->md));
1337 1338
}

1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361
static int device_flush_capable(struct dm_target *ti, struct dm_dev *dev,
				sector_t start, sector_t len, void *data)
{
	unsigned flush = (*(unsigned *)data);
	struct request_queue *q = bdev_get_queue(dev->bdev);

	return q && (q->flush_flags & flush);
}

static bool dm_table_supports_flush(struct dm_table *t, unsigned flush)
{
	struct dm_target *ti;
	unsigned i = 0;

	/*
	 * Require at least one underlying device to support flushes.
	 * t->devices includes internal dm devices such as mirror logs
	 * so we need to use iterate_devices here, which targets
	 * supporting flushes must provide.
	 */
	while (i < dm_table_get_num_targets(t)) {
		ti = dm_table_get_target(t, i++);

1362
		if (!ti->num_flush_bios)
1363 1364
			continue;

1365 1366 1367
		if (ti->flush_supported)
			return 1;

1368 1369 1370 1371 1372 1373 1374 1375
		if (ti->type->iterate_devices &&
		    ti->type->iterate_devices(ti, device_flush_capable, &flush))
			return 1;
	}

	return 0;
}

1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391
static bool dm_table_discard_zeroes_data(struct dm_table *t)
{
	struct dm_target *ti;
	unsigned i = 0;

	/* Ensure that all targets supports discard_zeroes_data. */
	while (i < dm_table_get_num_targets(t)) {
		ti = dm_table_get_target(t, i++);

		if (ti->discard_zeroes_data_unsupported)
			return 0;
	}

	return 1;
}

1392 1393 1394 1395 1396 1397 1398 1399
static int device_is_nonrot(struct dm_target *ti, struct dm_dev *dev,
			    sector_t start, sector_t len, void *data)
{
	struct request_queue *q = bdev_get_queue(dev->bdev);

	return q && blk_queue_nonrot(q);
}

1400 1401 1402 1403 1404 1405 1406 1407 1408 1409
static int device_is_not_random(struct dm_target *ti, struct dm_dev *dev,
			     sector_t start, sector_t len, void *data)
{
	struct request_queue *q = bdev_get_queue(dev->bdev);

	return q && !blk_queue_add_random(q);
}

static bool dm_table_all_devices_attribute(struct dm_table *t,
					   iterate_devices_callout_fn func)
1410 1411 1412 1413 1414 1415 1416 1417
{
	struct dm_target *ti;
	unsigned i = 0;

	while (i < dm_table_get_num_targets(t)) {
		ti = dm_table_get_target(t, i++);

		if (!ti->type->iterate_devices ||
1418
		    !ti->type->iterate_devices(ti, func, NULL))
1419 1420 1421 1422 1423 1424
			return 0;
	}

	return 1;
}

1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440
static int device_not_write_same_capable(struct dm_target *ti, struct dm_dev *dev,
					 sector_t start, sector_t len, void *data)
{
	struct request_queue *q = bdev_get_queue(dev->bdev);

	return q && !q->limits.max_write_same_sectors;
}

static bool dm_table_supports_write_same(struct dm_table *t)
{
	struct dm_target *ti;
	unsigned i = 0;

	while (i < dm_table_get_num_targets(t)) {
		ti = dm_table_get_target(t, i++);

1441
		if (!ti->num_write_same_bios)
1442 1443 1444 1445 1446 1447 1448 1449 1450 1451
			return false;

		if (!ti->type->iterate_devices ||
		    !ti->type->iterate_devices(ti, device_not_write_same_capable, NULL))
			return false;
	}

	return true;
}

1452 1453
void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
			       struct queue_limits *limits)
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Linus Torvalds 已提交
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{
1455 1456
	unsigned flush = 0;

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	/*
1458
	 * Copy table's limits to the DM device's request_queue
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1459
	 */
1460
	q->limits = *limits;
1461

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	if (!dm_table_supports_discards(t))
		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
	else
		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);

1467 1468 1469 1470 1471 1472 1473
	if (dm_table_supports_flush(t, REQ_FLUSH)) {
		flush |= REQ_FLUSH;
		if (dm_table_supports_flush(t, REQ_FUA))
			flush |= REQ_FUA;
	}
	blk_queue_flush(q, flush);

1474 1475 1476
	if (!dm_table_discard_zeroes_data(t))
		q->limits.discard_zeroes_data = 0;

1477 1478
	/* Ensure that all underlying devices are non-rotational. */
	if (dm_table_all_devices_attribute(t, device_is_nonrot))
1479 1480 1481 1482
		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
	else
		queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q);

1483 1484
	if (!dm_table_supports_write_same(t))
		q->limits.max_write_same_sectors = 0;
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1485

1486
	dm_table_set_integrity(t);
1487

1488 1489 1490 1491 1492 1493 1494 1495 1496
	/*
	 * Determine whether or not this queue's I/O timings contribute
	 * to the entropy pool, Only request-based targets use this.
	 * Clear QUEUE_FLAG_ADD_RANDOM if any underlying device does not
	 * have it set.
	 */
	if (blk_queue_add_random(q) && dm_table_all_devices_attribute(t, device_is_not_random))
		queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, q);

1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508
	/*
	 * QUEUE_FLAG_STACKABLE must be set after all queue settings are
	 * visible to other CPUs because, once the flag is set, incoming bios
	 * are processed by request-based dm, which refers to the queue
	 * settings.
	 * Until the flag set, bios are passed to bio-based dm and queued to
	 * md->deferred where queue settings are not needed yet.
	 * Those bios are passed to request-based dm at the resume time.
	 */
	smp_mb();
	if (dm_table_request_based(t))
		queue_flag_set_unlocked(QUEUE_FLAG_STACKABLE, q);
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}

unsigned int dm_table_get_num_targets(struct dm_table *t)
{
	return t->num_targets;
}

struct list_head *dm_table_get_devices(struct dm_table *t)
{
	return &t->devices;
}

1521
fmode_t dm_table_get_mode(struct dm_table *t)
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1522 1523 1524
{
	return t->mode;
}
1525
EXPORT_SYMBOL(dm_table_get_mode);
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1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544

static void suspend_targets(struct dm_table *t, unsigned postsuspend)
{
	int i = t->num_targets;
	struct dm_target *ti = t->targets;

	while (i--) {
		if (postsuspend) {
			if (ti->type->postsuspend)
				ti->type->postsuspend(ti);
		} else if (ti->type->presuspend)
			ti->type->presuspend(ti);

		ti++;
	}
}

void dm_table_presuspend_targets(struct dm_table *t)
{
1545 1546 1547
	if (!t)
		return;

1548
	suspend_targets(t, 0);
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1549 1550 1551 1552
}

void dm_table_postsuspend_targets(struct dm_table *t)
{
1553 1554 1555
	if (!t)
		return;

1556
	suspend_targets(t, 1);
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1557 1558
}

1559
int dm_table_resume_targets(struct dm_table *t)
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{
1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572
	int i, r = 0;

	for (i = 0; i < t->num_targets; i++) {
		struct dm_target *ti = t->targets + i;

		if (!ti->type->preresume)
			continue;

		r = ti->type->preresume(ti);
		if (r)
			return r;
	}
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	for (i = 0; i < t->num_targets; i++) {
		struct dm_target *ti = t->targets + i;

		if (ti->type->resume)
			ti->type->resume(ti);
	}
1580 1581

	return 0;
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}

1584 1585 1586 1587 1588 1589
void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb)
{
	list_add(&cb->list, &t->target_callbacks);
}
EXPORT_SYMBOL_GPL(dm_table_add_target_callbacks);

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1590 1591
int dm_table_any_congested(struct dm_table *t, int bdi_bits)
{
1592
	struct dm_dev_internal *dd;
1593
	struct list_head *devices = dm_table_get_devices(t);
1594
	struct dm_target_callbacks *cb;
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1595 1596
	int r = 0;

1597
	list_for_each_entry(dd, devices, list) {
1598
		struct request_queue *q = bdev_get_queue(dd->dm_dev.bdev);
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1599 1600 1601 1602 1603 1604 1605 1606
		char b[BDEVNAME_SIZE];

		if (likely(q))
			r |= bdi_congested(&q->backing_dev_info, bdi_bits);
		else
			DMWARN_LIMIT("%s: any_congested: nonexistent device %s",
				     dm_device_name(t->md),
				     bdevname(dd->dm_dev.bdev, b));
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1607 1608
	}

1609 1610 1611 1612
	list_for_each_entry(cb, &t->target_callbacks, list)
		if (cb->congested_fn)
			r |= cb->congested_fn(cb, bdi_bits);

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	return r;
}

1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629
int dm_table_any_busy_target(struct dm_table *t)
{
	unsigned i;
	struct dm_target *ti;

	for (i = 0; i < t->num_targets; i++) {
		ti = t->targets + i;
		if (ti->type->busy && ti->type->busy(ti))
			return 1;
	}

	return 0;
}

1630 1631 1632 1633
struct mapped_device *dm_table_get_md(struct dm_table *t)
{
	return t->md;
}
1634
EXPORT_SYMBOL(dm_table_get_md);
1635

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1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649
static int device_discard_capable(struct dm_target *ti, struct dm_dev *dev,
				  sector_t start, sector_t len, void *data)
{
	struct request_queue *q = bdev_get_queue(dev->bdev);

	return q && blk_queue_discard(q);
}

bool dm_table_supports_discards(struct dm_table *t)
{
	struct dm_target *ti;
	unsigned i = 0;

	/*
1650 1651
	 * Unless any target used by the table set discards_supported,
	 * require at least one underlying device to support discards.
M
Mike Snitzer 已提交
1652 1653
	 * t->devices includes internal dm devices such as mirror logs
	 * so we need to use iterate_devices here, which targets
1654
	 * supporting discard selectively must provide.
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Mike Snitzer 已提交
1655 1656 1657 1658
	 */
	while (i < dm_table_get_num_targets(t)) {
		ti = dm_table_get_target(t, i++);

1659
		if (!ti->num_discard_bios)
1660 1661
			continue;

1662 1663 1664
		if (ti->discards_supported)
			return 1;

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1665 1666 1667 1668 1669 1670 1671
		if (ti->type->iterate_devices &&
		    ti->type->iterate_devices(ti, device_discard_capable, NULL))
			return 1;
	}

	return 0;
}
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