fs/btrfs/volumes.c

/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */
#include <linux/sched.h>
#include <linux/bio.h>
#include <linux/slab.h>
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/random.h>
#include <linux/iocontext.h>
#include <linux/capability.h>
#include <linux/ratelimit.h>
#include <linux/kthread.h>
#include <linux/raid/pq.h>
#include <linux/semaphore.h>
#include <asm/div64.h>
#include "ctree.h"
#include "extent_map.h"
#include "disk-io.h"
#include "transaction.h"
#include "print-tree.h"
#include "volumes.h"
#include "raid56.h"
#include "async-thread.h"
#include "check-integrity.h"
#include "rcu-string.h"
#include "math.h"
#include "dev-replace.h"
#include "sysfs.h"

const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
	[BTRFS_RAID_RAID10] = {
		.sub_stripes	= 2,
		.dev_stripes	= 1,
		.devs_max	= 0,	/* 0 == as many as possible */
		.devs_min	= 4,
		.tolerated_failures = 1,
		.devs_increment	= 2,
		.ncopies	= 2,
	},
	[BTRFS_RAID_RAID1] = {
		.sub_stripes	= 1,
		.dev_stripes	= 1,
		.devs_max	= 2,
		.devs_min	= 2,
		.tolerated_failures = 1,
		.devs_increment	= 2,
		.ncopies	= 2,
	},
	[BTRFS_RAID_DUP] = {
		.sub_stripes	= 1,
		.dev_stripes	= 2,
		.devs_max	= 1,
		.devs_min	= 1,
		.tolerated_failures = 0,
		.devs_increment	= 1,
		.ncopies	= 2,
	},
	[BTRFS_RAID_RAID0] = {
		.sub_stripes	= 1,
		.dev_stripes	= 1,
		.devs_max	= 0,
		.devs_min	= 2,
		.tolerated_failures = 0,
		.devs_increment	= 1,
		.ncopies	= 1,
	},
	[BTRFS_RAID_SINGLE] = {
		.sub_stripes	= 1,
		.dev_stripes	= 1,
		.devs_max	= 1,
		.devs_min	= 1,
		.tolerated_failures = 0,
		.devs_increment	= 1,
		.ncopies	= 1,
	},
	[BTRFS_RAID_RAID5] = {
		.sub_stripes	= 1,
		.dev_stripes	= 1,
		.devs_max	= 0,
		.devs_min	= 2,
		.tolerated_failures = 1,
		.devs_increment	= 1,
		.ncopies	= 2,
	},
	[BTRFS_RAID_RAID6] = {
		.sub_stripes	= 1,
		.dev_stripes	= 1,
		.devs_max	= 0,
		.devs_min	= 3,
		.tolerated_failures = 2,
		.devs_increment	= 1,
		.ncopies	= 3,
	},
};

const u64 const btrfs_raid_group[BTRFS_NR_RAID_TYPES] = {
	[BTRFS_RAID_RAID10] = BTRFS_BLOCK_GROUP_RAID10,
	[BTRFS_RAID_RAID1]  = BTRFS_BLOCK_GROUP_RAID1,
	[BTRFS_RAID_DUP]    = BTRFS_BLOCK_GROUP_DUP,
	[BTRFS_RAID_RAID0]  = BTRFS_BLOCK_GROUP_RAID0,
	[BTRFS_RAID_SINGLE] = 0,
	[BTRFS_RAID_RAID5]  = BTRFS_BLOCK_GROUP_RAID5,
	[BTRFS_RAID_RAID6]  = BTRFS_BLOCK_GROUP_RAID6,
};

static int init_first_rw_device(struct btrfs_trans_handle *trans,
				struct btrfs_root *root,
				struct btrfs_device *device);
static int btrfs_relocate_sys_chunks(struct btrfs_root *root);
static void __btrfs_reset_dev_stats(struct btrfs_device *dev);
static void btrfs_dev_stat_print_on_error(struct btrfs_device *dev);
static void btrfs_dev_stat_print_on_load(struct btrfs_device *device);

DEFINE_MUTEX(uuid_mutex);
static LIST_HEAD(fs_uuids);
struct list_head *btrfs_get_fs_uuids(void)
{
	return &fs_uuids;
}

static struct btrfs_fs_devices *__alloc_fs_devices(void)
{
	struct btrfs_fs_devices *fs_devs;

	fs_devs = kzalloc(sizeof(*fs_devs), GFP_NOFS);
	if (!fs_devs)
		return ERR_PTR(-ENOMEM);

	mutex_init(&fs_devs->device_list_mutex);

	INIT_LIST_HEAD(&fs_devs->devices);
	INIT_LIST_HEAD(&fs_devs->resized_devices);
	INIT_LIST_HEAD(&fs_devs->alloc_list);
	INIT_LIST_HEAD(&fs_devs->list);

	return fs_devs;
}

/**
 * alloc_fs_devices - allocate struct btrfs_fs_devices
 * @fsid:	a pointer to UUID for this FS.  If NULL a new UUID is
 *		generated.
 *
 * Return: a pointer to a new &struct btrfs_fs_devices on success;
 * ERR_PTR() on error.  Returned struct is not linked onto any lists and
 * can be destroyed with kfree() right away.
 */
static struct btrfs_fs_devices *alloc_fs_devices(const u8 *fsid)
{
	struct btrfs_fs_devices *fs_devs;

	fs_devs = __alloc_fs_devices();
	if (IS_ERR(fs_devs))
		return fs_devs;

	if (fsid)
		memcpy(fs_devs->fsid, fsid, BTRFS_FSID_SIZE);
	else
		generate_random_uuid(fs_devs->fsid);

	return fs_devs;
}

static void free_fs_devices(struct btrfs_fs_devices *fs_devices)
{
	struct btrfs_device *device;
	WARN_ON(fs_devices->opened);
	while (!list_empty(&fs_devices->devices)) {
		device = list_entry(fs_devices->devices.next,
				    struct btrfs_device, dev_list);
		list_del(&device->dev_list);
		rcu_string_free(device->name);
		kfree(device);
	}
	kfree(fs_devices);
}

static void btrfs_kobject_uevent(struct block_device *bdev,
				 enum kobject_action action)
{
	int ret;

	ret = kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, action);
	if (ret)
		pr_warn("BTRFS: Sending event '%d' to kobject: '%s' (%p): failed\n",
			action,
			kobject_name(&disk_to_dev(bdev->bd_disk)->kobj),
			&disk_to_dev(bdev->bd_disk)->kobj);
}

void btrfs_cleanup_fs_uuids(void)
{
	struct btrfs_fs_devices *fs_devices;

	while (!list_empty(&fs_uuids)) {
		fs_devices = list_entry(fs_uuids.next,
					struct btrfs_fs_devices, list);
		list_del(&fs_devices->list);
		free_fs_devices(fs_devices);
	}
}

static struct btrfs_device *__alloc_device(void)
{
	struct btrfs_device *dev;

	dev = kzalloc(sizeof(*dev), GFP_NOFS);
	if (!dev)
		return ERR_PTR(-ENOMEM);

	INIT_LIST_HEAD(&dev->dev_list);
	INIT_LIST_HEAD(&dev->dev_alloc_list);
	INIT_LIST_HEAD(&dev->resized_list);

	spin_lock_init(&dev->io_lock);

	spin_lock_init(&dev->reada_lock);
	atomic_set(&dev->reada_in_flight, 0);
	atomic_set(&dev->dev_stats_ccnt, 0);
	btrfs_device_data_ordered_init(dev);
	INIT_RADIX_TREE(&dev->reada_zones, GFP_NOFS & ~__GFP_DIRECT_RECLAIM);
	INIT_RADIX_TREE(&dev->reada_extents, GFP_NOFS & ~__GFP_DIRECT_RECLAIM);

	return dev;
}

static noinline struct btrfs_device *__find_device(struct list_head *head,
						   u64 devid, u8 *uuid)
{
	struct btrfs_device *dev;

	list_for_each_entry(dev, head, dev_list) {
		if (dev->devid == devid &&
		    (!uuid || !memcmp(dev->uuid, uuid, BTRFS_UUID_SIZE))) {
			return dev;
		}
	}
	return NULL;
}

static noinline struct btrfs_fs_devices *find_fsid(u8 *fsid)
{
	struct btrfs_fs_devices *fs_devices;

	list_for_each_entry(fs_devices, &fs_uuids, list) {
		if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0)
			return fs_devices;
	}
	return NULL;
}

static int
btrfs_get_bdev_and_sb(const char *device_path, fmode_t flags, void *holder,
		      int flush, struct block_device **bdev,
		      struct buffer_head **bh)
{
	int ret;

	*bdev = blkdev_get_by_path(device_path, flags, holder);

	if (IS_ERR(*bdev)) {
		ret = PTR_ERR(*bdev);
		goto error;
	}

	if (flush)
		filemap_write_and_wait((*bdev)->bd_inode->i_mapping);
	ret = set_blocksize(*bdev, 4096);
	if (ret) {
		blkdev_put(*bdev, flags);
		goto error;
	}
	invalidate_bdev(*bdev);
	*bh = btrfs_read_dev_super(*bdev);
	if (IS_ERR(*bh)) {
		ret = PTR_ERR(*bh);
		blkdev_put(*bdev, flags);
		goto error;
	}

	return 0;

error:
	*bdev = NULL;
	*bh = NULL;
	return ret;
}

static void requeue_list(struct btrfs_pending_bios *pending_bios,
			struct bio *head, struct bio *tail)
{

	struct bio *old_head;

	old_head = pending_bios->head;
	pending_bios->head = head;
	if (pending_bios->tail)
		tail->bi_next = old_head;
	else
		pending_bios->tail = tail;
}

/*
 * we try to collect pending bios for a device so we don't get a large
 * number of procs sending bios down to the same device.  This greatly
 * improves the schedulers ability to collect and merge the bios.
 *
 * But, it also turns into a long list of bios to process and that is sure
 * to eventually make the worker thread block.  The solution here is to
 * make some progress and then put this work struct back at the end of
 * the list if the block device is congested.  This way, multiple devices
 * can make progress from a single worker thread.
 */
static noinline void run_scheduled_bios(struct btrfs_device *device)
{
	struct bio *pending;
	struct backing_dev_info *bdi;
	struct btrfs_fs_info *fs_info;
	struct btrfs_pending_bios *pending_bios;
	struct bio *tail;
	struct bio *cur;
	int again = 0;
	unsigned long num_run;
	unsigned long batch_run = 0;
	unsigned long limit;
	unsigned long last_waited = 0;
	int force_reg = 0;
	int sync_pending = 0;
	struct blk_plug plug;

	/*
	 * this function runs all the bios we've collected for
	 * a particular device.  We don't want to wander off to
	 * another device without first sending all of these down.
	 * So, setup a plug here and finish it off before we return
	 */
	blk_start_plug(&plug);

	bdi = blk_get_backing_dev_info(device->bdev);
	fs_info = device->dev_root->fs_info;
	limit = btrfs_async_submit_limit(fs_info);
	limit = limit * 2 / 3;

loop:
	spin_lock(&device->io_lock);

loop_lock:
	num_run = 0;

	/* take all the bios off the list at once and process them
	 * later on (without the lock held).  But, remember the
	 * tail and other pointers so the bios can be properly reinserted
	 * into the list if we hit congestion
	 */
	if (!force_reg && device->pending_sync_bios.head) {
		pending_bios = &device->pending_sync_bios;
		force_reg = 1;
	} else {
		pending_bios = &device->pending_bios;
		force_reg = 0;
	}

	pending = pending_bios->head;
	tail = pending_bios->tail;
	WARN_ON(pending && !tail);

	/*
	 * if pending was null this time around, no bios need processing
	 * at all and we can stop.  Otherwise it'll loop back up again
	 * and do an additional check so no bios are missed.
	 *
	 * device->running_pending is used to synchronize with the
	 * schedule_bio code.
	 */
	if (device->pending_sync_bios.head == NULL &&
	    device->pending_bios.head == NULL) {
		again = 0;
		device->running_pending = 0;
	} else {
		again = 1;
		device->running_pending = 1;
	}

	pending_bios->head = NULL;
	pending_bios->tail = NULL;

	spin_unlock(&device->io_lock);

	while (pending) {

		rmb();
		/* we want to work on both lists, but do more bios on the
		 * sync list than the regular list
		 */
		if ((num_run > 32 &&
		    pending_bios != &device->pending_sync_bios &&
		    device->pending_sync_bios.head) ||
		   (num_run > 64 && pending_bios == &device->pending_sync_bios &&
		    device->pending_bios.head)) {
			spin_lock(&device->io_lock);
			requeue_list(pending_bios, pending, tail);
			goto loop_lock;
		}

		cur = pending;
		pending = pending->bi_next;
		cur->bi_next = NULL;

		/*
		 * atomic_dec_return implies a barrier for waitqueue_active
		 */
		if (atomic_dec_return(&fs_info->nr_async_bios) < limit &&
		    waitqueue_active(&fs_info->async_submit_wait))
			wake_up(&fs_info->async_submit_wait);

		BUG_ON(atomic_read(&cur->__bi_cnt) == 0);

		/*
		 * if we're doing the sync list, record that our
		 * plug has some sync requests on it
		 *
		 * If we're doing the regular list and there are
		 * sync requests sitting around, unplug before
		 * we add more
		 */
		if (pending_bios == &device->pending_sync_bios) {
			sync_pending = 1;
		} else if (sync_pending) {
			blk_finish_plug(&plug);
			blk_start_plug(&plug);
			sync_pending = 0;
		}

		btrfsic_submit_bio(cur->bi_rw, cur);
		num_run++;
		batch_run++;

		cond_resched();

		/*
		 * we made progress, there is more work to do and the bdi
		 * is now congested.  Back off and let other work structs
		 * run instead
		 */
		if (pending && bdi_write_congested(bdi) && batch_run > 8 &&
		    fs_info->fs_devices->open_devices > 1) {
			struct io_context *ioc;

			ioc = current->io_context;

			/*
			 * the main goal here is that we don't want to
			 * block if we're going to be able to submit
			 * more requests without blocking.
			 *
			 * This code does two great things, it pokes into
			 * the elevator code from a filesystem _and_
			 * it makes assumptions about how batching works.
			 */
			if (ioc && ioc->nr_batch_requests > 0 &&
			    time_before(jiffies, ioc->last_waited + HZ/50UL) &&
			    (last_waited == 0 ||
			     ioc->last_waited == last_waited)) {
				/*
				 * we want to go through our batch of
				 * requests and stop.  So, we copy out
				 * the ioc->last_waited time and test
				 * against it before looping
				 */
				last_waited = ioc->last_waited;
				cond_resched();
				continue;
			}
			spin_lock(&device->io_lock);
			requeue_list(pending_bios, pending, tail);
			device->running_pending = 1;

			spin_unlock(&device->io_lock);
			btrfs_queue_work(fs_info->submit_workers,
					 &device->work);
			goto done;
		}
		/* unplug every 64 requests just for good measure */
		if (batch_run % 64 == 0) {
			blk_finish_plug(&plug);
			blk_start_plug(&plug);
			sync_pending = 0;
		}
	}

	cond_resched();
	if (again)
		goto loop;

	spin_lock(&device->io_lock);
	if (device->pending_bios.head || device->pending_sync_bios.head)
		goto loop_lock;
	spin_unlock(&device->io_lock);

done:
	blk_finish_plug(&plug);
}

static void pending_bios_fn(struct btrfs_work *work)
{
	struct btrfs_device *device;

	device = container_of(work, struct btrfs_device, work);
	run_scheduled_bios(device);
}


void btrfs_free_stale_device(struct btrfs_device *cur_dev)
{
	struct btrfs_fs_devices *fs_devs;
	struct btrfs_device *dev;

	if (!cur_dev->name)
		return;

	list_for_each_entry(fs_devs, &fs_uuids, list) {
		int del = 1;

		if (fs_devs->opened)
			continue;
		if (fs_devs->seeding)
			continue;

		list_for_each_entry(dev, &fs_devs->devices, dev_list) {

			if (dev == cur_dev)
				continue;
			if (!dev->name)
				continue;

			/*
			 * Todo: This won't be enough. What if the same device
			 * comes back (with new uuid and) with its mapper path?
			 * But for now, this does help as mostly an admin will
			 * either use mapper or non mapper path throughout.
			 */
			rcu_read_lock();
			del = strcmp(rcu_str_deref(dev->name),
						rcu_str_deref(cur_dev->name));
			rcu_read_unlock();
			if (!del)
				break;
		}

		if (!del) {
			/* delete the stale device */
			if (fs_devs->num_devices == 1) {
				btrfs_sysfs_remove_fsid(fs_devs);
				list_del(&fs_devs->list);
				free_fs_devices(fs_devs);
			} else {
				fs_devs->num_devices--;
				list_del(&dev->dev_list);
				rcu_string_free(dev->name);
				kfree(dev);
			}
			break;
		}
	}
}

/*
 * Add new device to list of registered devices
 *
 * Returns:
 * 1   - first time device is seen
 * 0   - device already known
 * < 0 - error
 */
static noinline int device_list_add(const char *path,
			   struct btrfs_super_block *disk_super,
			   u64 devid, struct btrfs_fs_devices **fs_devices_ret)
{
	struct btrfs_device *device;
	struct btrfs_fs_devices *fs_devices;
	struct rcu_string *name;
	int ret = 0;
	u64 found_transid = btrfs_super_generation(disk_super);

	fs_devices = find_fsid(disk_super->fsid);
	if (!fs_devices) {
		fs_devices = alloc_fs_devices(disk_super->fsid);
		if (IS_ERR(fs_devices))
			return PTR_ERR(fs_devices);

		list_add(&fs_devices->list, &fs_uuids);

		device = NULL;
	} else {
		device = __find_device(&fs_devices->devices, devid,
				       disk_super->dev_item.uuid);
	}

	if (!device) {
		if (fs_devices->opened)
			return -EBUSY;

		device = btrfs_alloc_device(NULL, &devid,
					    disk_super->dev_item.uuid);
		if (IS_ERR(device)) {
			/* we can safely leave the fs_devices entry around */
			return PTR_ERR(device);
		}

		name = rcu_string_strdup(path, GFP_NOFS);
		if (!name) {
			kfree(device);
			return -ENOMEM;
		}
		rcu_assign_pointer(device->name, name);

		mutex_lock(&fs_devices->device_list_mutex);
		list_add_rcu(&device->dev_list, &fs_devices->devices);
		fs_devices->num_devices++;
		mutex_unlock(&fs_devices->device_list_mutex);

		ret = 1;
		device->fs_devices = fs_devices;
	} else if (!device->name || strcmp(device->name->str, path)) {
		/*
		 * When FS is already mounted.
		 * 1. If you are here and if the device->name is NULL that
		 *    means this device was missing at time of FS mount.
		 * 2. If you are here and if the device->name is different
		 *    from 'path' that means either
		 *      a. The same device disappeared and reappeared with
		 *         different name. or
		 *      b. The missing-disk-which-was-replaced, has
		 *         reappeared now.
		 *
		 * We must allow 1 and 2a above. But 2b would be a spurious
		 * and unintentional.
		 *
		 * Further in case of 1 and 2a above, the disk at 'path'
		 * would have missed some transaction when it was away and
		 * in case of 2a the stale bdev has to be updated as well.
		 * 2b must not be allowed at all time.
		 */

		/*
		 * For now, we do allow update to btrfs_fs_device through the
		 * btrfs dev scan cli after FS has been mounted.  We're still
		 * tracking a problem where systems fail mount by subvolume id
		 * when we reject replacement on a mounted FS.
		 */
		if (!fs_devices->opened && found_transid < device->generation) {
			/*
			 * That is if the FS is _not_ mounted and if you
			 * are here, that means there is more than one
			 * disk with same uuid and devid.We keep the one
			 * with larger generation number or the last-in if
			 * generation are equal.
			 */
			return -EEXIST;
		}

		name = rcu_string_strdup(path, GFP_NOFS);
		if (!name)
			return -ENOMEM;
		rcu_string_free(device->name);
		rcu_assign_pointer(device->name, name);
		if (device->missing) {
			fs_devices->missing_devices--;
			device->missing = 0;
		}
	}

	/*
	 * Unmount does not free the btrfs_device struct but would zero
	 * generation along with most of the other members. So just update
	 * it back. We need it to pick the disk with largest generation
	 * (as above).
	 */
	if (!fs_devices->opened)
		device->generation = found_transid;

	/*
	 * if there is new btrfs on an already registered device,
	 * then remove the stale device entry.
	 */
	btrfs_free_stale_device(device);

	*fs_devices_ret = fs_devices;

	return ret;
}

static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
{
	struct btrfs_fs_devices *fs_devices;
	struct btrfs_device *device;
	struct btrfs_device *orig_dev;

	fs_devices = alloc_fs_devices(orig->fsid);
	if (IS_ERR(fs_devices))
		return fs_devices;

	mutex_lock(&orig->device_list_mutex);
	fs_devices->total_devices = orig->total_devices;

	/* We have held the volume lock, it is safe to get the devices. */
	list_for_each_entry(orig_dev, &orig->devices, dev_list) {
		struct rcu_string *name;

		device = btrfs_alloc_device(NULL, &orig_dev->devid,
					    orig_dev->uuid);
		if (IS_ERR(device))
			goto error;

		/*
		 * This is ok to do without rcu read locked because we hold the
		 * uuid mutex so nothing we touch in here is going to disappear.
		 */
		if (orig_dev->name) {
			name = rcu_string_strdup(orig_dev->name->str, GFP_NOFS);
			if (!name) {
				kfree(device);
				goto error;
			}
			rcu_assign_pointer(device->name, name);
		}

		list_add(&device->dev_list, &fs_devices->devices);
		device->fs_devices = fs_devices;
		fs_devices->num_devices++;
	}
	mutex_unlock(&orig->device_list_mutex);
	return fs_devices;
error:
	mutex_unlock(&orig->device_list_mutex);
	free_fs_devices(fs_devices);
	return ERR_PTR(-ENOMEM);
}

void btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices, int step)
{
	struct btrfs_device *device, *next;
	struct btrfs_device *latest_dev = NULL;

	mutex_lock(&uuid_mutex);
again:
	/* This is the initialized path, it is safe to release the devices. */
	list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
		if (device->in_fs_metadata) {
			if (!device->is_tgtdev_for_dev_replace &&
			    (!latest_dev ||
			     device->generation > latest_dev->generation)) {
				latest_dev = device;
			}
			continue;
		}

		if (device->devid == BTRFS_DEV_REPLACE_DEVID) {
			/*
			 * In the first step, keep the device which has
			 * the correct fsid and the devid that is used
			 * for the dev_replace procedure.
			 * In the second step, the dev_replace state is
			 * read from the device tree and it is known
			 * whether the procedure is really active or
			 * not, which means whether this device is
			 * used or whether it should be removed.
			 */
			if (step == 0 || device->is_tgtdev_for_dev_replace) {
				continue;
			}
		}
		if (device->bdev) {
			blkdev_put(device->bdev, device->mode);
			device->bdev = NULL;
			fs_devices->open_devices--;
		}
		if (device->writeable) {
			list_del_init(&device->dev_alloc_list);
			device->writeable = 0;
			if (!device->is_tgtdev_for_dev_replace)
				fs_devices->rw_devices--;
		}
		list_del_init(&device->dev_list);
		fs_devices->num_devices--;
		rcu_string_free(device->name);
		kfree(device);
	}

	if (fs_devices->seed) {
		fs_devices = fs_devices->seed;
		goto again;
	}

	fs_devices->latest_bdev = latest_dev->bdev;

	mutex_unlock(&uuid_mutex);
}

static void __free_device(struct work_struct *work)
{
	struct btrfs_device *device;

	device = container_of(work, struct btrfs_device, rcu_work);

	if (device->bdev)
		blkdev_put(device->bdev, device->mode);

	rcu_string_free(device->name);
	kfree(device);
}

static void free_device(struct rcu_head *head)
{
	struct btrfs_device *device;

	device = container_of(head, struct btrfs_device, rcu);

	INIT_WORK(&device->rcu_work, __free_device);
	schedule_work(&device->rcu_work);
}

static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
{
	struct btrfs_device *device, *tmp;

	if (--fs_devices->opened > 0)
		return 0;

	mutex_lock(&fs_devices->device_list_mutex);
	list_for_each_entry_safe(device, tmp, &fs_devices->devices, dev_list) {
		btrfs_close_one_device(device);
	}
	mutex_unlock(&fs_devices->device_list_mutex);

	WARN_ON(fs_devices->open_devices);
	WARN_ON(fs_devices->rw_devices);
	fs_devices->opened = 0;
	fs_devices->seeding = 0;

	return 0;
}

int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
{
	struct btrfs_fs_devices *seed_devices = NULL;
	int ret;

	mutex_lock(&uuid_mutex);
	ret = __btrfs_close_devices(fs_devices);
	if (!fs_devices->opened) {
		seed_devices = fs_devices->seed;
		fs_devices->seed = NULL;
	}
	mutex_unlock(&uuid_mutex);

	while (seed_devices) {
		fs_devices = seed_devices;
		seed_devices = fs_devices->seed;
		__btrfs_close_devices(fs_devices);
		free_fs_devices(fs_devices);
	}
	/*
	 * Wait for rcu kworkers under __btrfs_close_devices
	 * to finish all blkdev_puts so device is really
	 * free when umount is done.
	 */
	rcu_barrier();
	return ret;
}

static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
				fmode_t flags, void *holder)
{
	struct request_queue *q;
	struct block_device *bdev;
	struct list_head *head = &fs_devices->devices;
	struct btrfs_device *device;
	struct btrfs_device *latest_dev = NULL;
	struct buffer_head *bh;
	struct btrfs_super_block *disk_super;
	u64 devid;
	int seeding = 1;
	int ret = 0;

	flags |= FMODE_EXCL;

	list_for_each_entry(device, head, dev_list) {
		if (device->bdev)
			continue;
		if (!device->name)
			continue;

		/* Just open everything we can; ignore failures here */
		if (btrfs_get_bdev_and_sb(device->name->str, flags, holder, 1,
					    &bdev, &bh))
			continue;

		disk_super = (struct btrfs_super_block *)bh->b_data;
		devid = btrfs_stack_device_id(&disk_super->dev_item);
		if (devid != device->devid)
			goto error_brelse;

		if (memcmp(device->uuid, disk_super->dev_item.uuid,
			   BTRFS_UUID_SIZE))
			goto error_brelse;

		device->generation = btrfs_super_generation(disk_super);
		if (!latest_dev ||
		    device->generation > latest_dev->generation)
			latest_dev = device;

		if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING) {
			device->writeable = 0;
		} else {
			device->writeable = !bdev_read_only(bdev);
			seeding = 0;
		}

		q = bdev_get_queue(bdev);
		if (blk_queue_discard(q))
			device->can_discard = 1;

		device->bdev = bdev;
		device->in_fs_metadata = 0;
		device->mode = flags;

		if (!blk_queue_nonrot(bdev_get_queue(bdev)))
			fs_devices->rotating = 1;

		fs_devices->open_devices++;
		if (device->writeable &&
		    device->devid != BTRFS_DEV_REPLACE_DEVID) {
			fs_devices->rw_devices++;
			list_add(&device->dev_alloc_list,
				 &fs_devices->alloc_list);
		}
		brelse(bh);
		continue;

error_brelse:
		brelse(bh);
		blkdev_put(bdev, flags);
		continue;
	}
	if (fs_devices->open_devices == 0) {
		ret = -EINVAL;
		goto out;
	}
	fs_devices->seeding = seeding;
	fs_devices->opened = 1;
	fs_devices->latest_bdev = latest_dev->bdev;
	fs_devices->total_rw_bytes = 0;
out:
	return ret;
}

int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
		       fmode_t flags, void *holder)
{
	int ret;

	mutex_lock(&uuid_mutex);
	if (fs_devices->opened) {
		fs_devices->opened++;
		ret = 0;
	} else {
		ret = __btrfs_open_devices(fs_devices, flags, holder);
	}
	mutex_unlock(&uuid_mutex);
	return ret;
}

/*
 * Look for a btrfs signature on a device. This may be called out of the mount path
 * and we are not allowed to call set_blocksize during the scan. The superblock
 * is read via pagecache
 */
int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
			  struct btrfs_fs_devices **fs_devices_ret)
{
	struct btrfs_super_block *disk_super;
	struct block_device *bdev;
	struct page *page;
	void *p;
	int ret = -EINVAL;
	u64 devid;
	u64 transid;
	u64 total_devices;
	u64 bytenr;
	pgoff_t index;

	/*
	 * we would like to check all the supers, but that would make
	 * a btrfs mount succeed after a mkfs from a different FS.
	 * So, we need to add a special mount option to scan for
	 * later supers, using BTRFS_SUPER_MIRROR_MAX instead
	 */
	bytenr = btrfs_sb_offset(0);
	flags |= FMODE_EXCL;
	mutex_lock(&uuid_mutex);

	bdev = blkdev_get_by_path(path, flags, holder);

	if (IS_ERR(bdev)) {
		ret = PTR_ERR(bdev);
		goto error;
	}

	/* make sure our super fits in the device */
	if (bytenr + PAGE_CACHE_SIZE >= i_size_read(bdev->bd_inode))
		goto error_bdev_put;

	/* make sure our super fits in the page */
	if (sizeof(*disk_super) > PAGE_CACHE_SIZE)
		goto error_bdev_put;

	/* make sure our super doesn't straddle pages on disk */
	index = bytenr >> PAGE_CACHE_SHIFT;
	if ((bytenr + sizeof(*disk_super) - 1) >> PAGE_CACHE_SHIFT != index)
		goto error_bdev_put;

	/* pull in the page with our super */
	page = read_cache_page_gfp(bdev->bd_inode->i_mapping,
				   index, GFP_NOFS);

	if (IS_ERR_OR_NULL(page))
		goto error_bdev_put;

	p = kmap(page);

	/* align our pointer to the offset of the super block */
	disk_super = p + (bytenr & ~PAGE_CACHE_MASK);

	if (btrfs_super_bytenr(disk_super) != bytenr ||
	    btrfs_super_magic(disk_super) != BTRFS_MAGIC)
		goto error_unmap;

	devid = btrfs_stack_device_id(&disk_super->dev_item);
	transid = btrfs_super_generation(disk_super);
	total_devices = btrfs_super_num_devices(disk_super);

	ret = device_list_add(path, disk_super, devid, fs_devices_ret);
	if (ret > 0) {
		if (disk_super->label[0]) {
			if (disk_super->label[BTRFS_LABEL_SIZE - 1])
				disk_super->label[BTRFS_LABEL_SIZE - 1] = '\0';
			printk(KERN_INFO "BTRFS: device label %s ", disk_super->label);
		} else {
			printk(KERN_INFO "BTRFS: device fsid %pU ", disk_super->fsid);
		}

		printk(KERN_CONT "devid %llu transid %llu %s\n", devid, transid, path);
		ret = 0;
	}
	if (!ret && fs_devices_ret)
		(*fs_devices_ret)->total_devices = total_devices;

error_unmap:
	kunmap(page);
	page_cache_release(page);

error_bdev_put:
	blkdev_put(bdev, flags);
error:
	mutex_unlock(&uuid_mutex);
	return ret;
}

/* helper to account the used device space in the range */
int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
				   u64 end, u64 *length)
{
	struct btrfs_key key;
	struct btrfs_root *root = device->dev_root;
	struct btrfs_dev_extent *dev_extent;
	struct btrfs_path *path;
	u64 extent_end;
	int ret;
	int slot;
	struct extent_buffer *l;

	*length = 0;

	if (start >= device->total_bytes || device->is_tgtdev_for_dev_replace)
		return 0;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;
	path->reada = 2;

	key.objectid = device->devid;
	key.offset = start;
	key.type = BTRFS_DEV_EXTENT_KEY;

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto out;
	if (ret > 0) {
		ret = btrfs_previous_item(root, path, key.objectid, key.type);
		if (ret < 0)
			goto out;
	}

	while (1) {
		l = path->nodes[0];
		slot = path->slots[0];
		if (slot >= btrfs_header_nritems(l)) {
			ret = btrfs_next_leaf(root, path);
			if (ret == 0)
				continue;
			if (ret < 0)
				goto out;

			break;
		}
		btrfs_item_key_to_cpu(l, &key, slot);

		if (key.objectid < device->devid)
			goto next;

		if (key.objectid > device->devid)
			break;

		if (key.type != BTRFS_DEV_EXTENT_KEY)
			goto next;

		dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
		extent_end = key.offset + btrfs_dev_extent_length(l,
								  dev_extent);
		if (key.offset <= start && extent_end > end) {
			*length = end - start + 1;
			break;
		} else if (key.offset <= start && extent_end > start)
			*length += extent_end - start;
		else if (key.offset > start && extent_end <= end)
			*length += extent_end - key.offset;
		else if (key.offset > start && key.offset <= end) {
			*length += end - key.offset + 1;
			break;
		} else if (key.offset > end)
			break;

next:
		path->slots[0]++;
	}
	ret = 0;
out:
	btrfs_free_path(path);
	return ret;
}

static int contains_pending_extent(struct btrfs_transaction *transaction,
				   struct btrfs_device *device,
				   u64 *start, u64 len)
{
	struct btrfs_fs_info *fs_info = device->dev_root->fs_info;
	struct extent_map *em;
	struct list_head *search_list = &fs_info->pinned_chunks;
	int ret = 0;
	u64 physical_start = *start;

	if (transaction)
		search_list = &transaction->pending_chunks;
again:
	list_for_each_entry(em, search_list, list) {
		struct map_lookup *map;
		int i;

		map = (struct map_lookup *)em->bdev;
		for (i = 0; i < map->num_stripes; i++) {
			u64 end;

			if (map->stripes[i].dev != device)
				continue;
			if (map->stripes[i].physical >= physical_start + len ||
			    map->stripes[i].physical + em->orig_block_len <=
			    physical_start)
				continue;
			/*
			 * Make sure that while processing the pinned list we do
			 * not override our *start with a lower value, because
			 * we can have pinned chunks that fall within this
			 * device hole and that have lower physical addresses
			 * than the pending chunks we processed before. If we
			 * do not take this special care we can end up getting
			 * 2 pending chunks that start at the same physical
			 * device offsets because the end offset of a pinned
			 * chunk can be equal to the start offset of some
			 * pending chunk.
			 */
			end = map->stripes[i].physical + em->orig_block_len;
			if (end > *start) {
				*start = end;
				ret = 1;
			}
		}
	}
	if (search_list != &fs_info->pinned_chunks) {
		search_list = &fs_info->pinned_chunks;
		goto again;
	}

	return ret;
}


/*
 * find_free_dev_extent_start - find free space in the specified device
 * @device:	  the device which we search the free space in
 * @num_bytes:	  the size of the free space that we need
 * @search_start: the position from which to begin the search
 * @start:	  store the start of the free space.
 * @len:	  the size of the free space. that we find, or the size
 *		  of the max free space if we don't find suitable free space
 *
 * this uses a pretty simple search, the expectation is that it is
 * called very infrequently and that a given device has a small number
 * of extents
 *
 * @start is used to store the start of the free space if we find. But if we
 * don't find suitable free space, it will be used to store the start position
 * of the max free space.
 *
 * @len is used to store the size of the free space that we find.
 * But if we don't find suitable free space, it is used to store the size of
 * the max free space.
 */
int find_free_dev_extent_start(struct btrfs_transaction *transaction,
			       struct btrfs_device *device, u64 num_bytes,
			       u64 search_start, u64 *start, u64 *len)
{
	struct btrfs_key key;
	struct btrfs_root *root = device->dev_root;
	struct btrfs_dev_extent *dev_extent;
	struct btrfs_path *path;
	u64 hole_size;
	u64 max_hole_start;
	u64 max_hole_size;
	u64 extent_end;
	u64 search_end = device->total_bytes;
	int ret;
	int slot;
	struct extent_buffer *l;
	u64 min_search_start;

	/*
	 * We don't want to overwrite the superblock on the drive nor any area
	 * used by the boot loader (grub for example), so we make sure to start
	 * at an offset of at least 1MB.
	 */
	min_search_start = max(root->fs_info->alloc_start, 1024ull * 1024);
	search_start = max(search_start, min_search_start);

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	max_hole_start = search_start;
	max_hole_size = 0;

again:
	if (search_start >= search_end || device->is_tgtdev_for_dev_replace) {
		ret = -ENOSPC;
		goto out;
	}

	path->reada = 2;
	path->search_commit_root = 1;
	path->skip_locking = 1;

	key.objectid = device->devid;
	key.offset = search_start;
	key.type = BTRFS_DEV_EXTENT_KEY;

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto out;
	if (ret > 0) {
		ret = btrfs_previous_item(root, path, key.objectid, key.type);
		if (ret < 0)
			goto out;
	}

	while (1) {
		l = path->nodes[0];
		slot = path->slots[0];
		if (slot >= btrfs_header_nritems(l)) {
			ret = btrfs_next_leaf(root, path);
			if (ret == 0)
				continue;
			if (ret < 0)
				goto out;

			break;
		}
		btrfs_item_key_to_cpu(l, &key, slot);

		if (key.objectid < device->devid)
			goto next;

		if (key.objectid > device->devid)
			break;

		if (key.type != BTRFS_DEV_EXTENT_KEY)
			goto next;

		if (key.offset > search_start) {
			hole_size = key.offset - search_start;

			/*
			 * Have to check before we set max_hole_start, otherwise
			 * we could end up sending back this offset anyway.
			 */
			if (contains_pending_extent(transaction, device,
						    &search_start,
						    hole_size)) {
				if (key.offset >= search_start) {
					hole_size = key.offset - search_start;
				} else {
					WARN_ON_ONCE(1);
					hole_size = 0;
				}
			}

			if (hole_size > max_hole_size) {
				max_hole_start = search_start;
				max_hole_size = hole_size;
			}

			/*
			 * If this free space is greater than which we need,
			 * it must be the max free space that we have found
			 * until now, so max_hole_start must point to the start
			 * of this free space and the length of this free space
			 * is stored in max_hole_size. Thus, we return
			 * max_hole_start and max_hole_size and go back to the
			 * caller.
			 */
			if (hole_size >= num_bytes) {
				ret = 0;
				goto out;
			}
		}

		dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
		extent_end = key.offset + btrfs_dev_extent_length(l,
								  dev_extent);
		if (extent_end > search_start)
			search_start = extent_end;
next:
		path->slots[0]++;
		cond_resched();
	}

	/*
	 * At this point, search_start should be the end of
	 * allocated dev extents, and when shrinking the device,
	 * search_end may be smaller than search_start.
	 */
	if (search_end > search_start) {
		hole_size = search_end - search_start;

		if (contains_pending_extent(transaction, device, &search_start,
					    hole_size)) {
			btrfs_release_path(path);
			goto again;
		}

		if (hole_size > max_hole_size) {
			max_hole_start = search_start;
			max_hole_size = hole_size;
		}
	}

	/* See above. */
	if (max_hole_size < num_bytes)
		ret = -ENOSPC;
	else
		ret = 0;

out:
	btrfs_free_path(path);
	*start = max_hole_start;
	if (len)
		*len = max_hole_size;
	return ret;
}

int find_free_dev_extent(struct btrfs_trans_handle *trans,
			 struct btrfs_device *device, u64 num_bytes,
			 u64 *start, u64 *len)
{
	/* FIXME use last free of some kind */
	return find_free_dev_extent_start(trans->transaction, device,
					  num_bytes, 0, start, len);
}

static int btrfs_free_dev_extent(struct btrfs_trans_handle *trans,
			  struct btrfs_device *device,
			  u64 start, u64 *dev_extent_len)
{
	int ret;
	struct btrfs_path *path;
	struct btrfs_root *root = device->dev_root;
	struct btrfs_key key;
	struct btrfs_key found_key;
	struct extent_buffer *leaf = NULL;
	struct btrfs_dev_extent *extent = NULL;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	key.objectid = device->devid;
	key.offset = start;
	key.type = BTRFS_DEV_EXTENT_KEY;
again:
	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
	if (ret > 0) {
		ret = btrfs_previous_item(root, path, key.objectid,
					  BTRFS_DEV_EXTENT_KEY);
		if (ret)
			goto out;
		leaf = path->nodes[0];
		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
		extent = btrfs_item_ptr(leaf, path->slots[0],
					struct btrfs_dev_extent);
		BUG_ON(found_key.offset > start || found_key.offset +
		       btrfs_dev_extent_length(leaf, extent) < start);
		key = found_key;
		btrfs_release_path(path);
		goto again;
	} else if (ret == 0) {
		leaf = path->nodes[0];
		extent = btrfs_item_ptr(leaf, path->slots[0],
					struct btrfs_dev_extent);
	} else {
		btrfs_std_error(root->fs_info, ret, "Slot search failed");
		goto out;
	}

	*dev_extent_len = btrfs_dev_extent_length(leaf, extent);

	ret = btrfs_del_item(trans, root, path);
	if (ret) {
		btrfs_std_error(root->fs_info, ret,
			    "Failed to remove dev extent item");
	} else {
		set_bit(BTRFS_TRANS_HAVE_FREE_BGS, &trans->transaction->flags);
	}
out:
	btrfs_free_path(path);
	return ret;
}

static int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
				  struct btrfs_device *device,
				  u64 chunk_tree, u64 chunk_objectid,
				  u64 chunk_offset, u64 start, u64 num_bytes)
{
	int ret;
	struct btrfs_path *path;
	struct btrfs_root *root = device->dev_root;
	struct btrfs_dev_extent *extent;
	struct extent_buffer *leaf;
	struct btrfs_key key;

	WARN_ON(!device->in_fs_metadata);
	WARN_ON(device->is_tgtdev_for_dev_replace);
	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	key.objectid = device->devid;
	key.offset = start;
	key.type = BTRFS_DEV_EXTENT_KEY;
	ret = btrfs_insert_empty_item(trans, root, path, &key,
				      sizeof(*extent));
	if (ret)
		goto out;

	leaf = path->nodes[0];
	extent = btrfs_item_ptr(leaf, path->slots[0],
				struct btrfs_dev_extent);
	btrfs_set_dev_extent_chunk_tree(leaf, extent, chunk_tree);
	btrfs_set_dev_extent_chunk_objectid(leaf, extent, chunk_objectid);
	btrfs_set_dev_extent_chunk_offset(leaf, extent, chunk_offset);

	write_extent_buffer(leaf, root->fs_info->chunk_tree_uuid,
		    btrfs_dev_extent_chunk_tree_uuid(extent), BTRFS_UUID_SIZE);

	btrfs_set_dev_extent_length(leaf, extent, num_bytes);
	btrfs_mark_buffer_dirty(leaf);
out:
	btrfs_free_path(path);
	return ret;
}

static u64 find_next_chunk(struct btrfs_fs_info *fs_info)
{
	struct extent_map_tree *em_tree;
	struct extent_map *em;
	struct rb_node *n;
	u64 ret = 0;

	em_tree = &fs_info->mapping_tree.map_tree;
	read_lock(&em_tree->lock);
	n = rb_last(&em_tree->map);
	if (n) {
		em = rb_entry(n, struct extent_map, rb_node);
		ret = em->start + em->len;
	}
	read_unlock(&em_tree->lock);

	return ret;
}

static noinline int find_next_devid(struct btrfs_fs_info *fs_info,
				    u64 *devid_ret)
{
	int ret;
	struct btrfs_key key;
	struct btrfs_key found_key;
	struct btrfs_path *path;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
	key.type = BTRFS_DEV_ITEM_KEY;
	key.offset = (u64)-1;

	ret = btrfs_search_slot(NULL, fs_info->chunk_root, &key, path, 0, 0);
	if (ret < 0)
		goto error;

	BUG_ON(ret == 0); /* Corruption */

	ret = btrfs_previous_item(fs_info->chunk_root, path,
				  BTRFS_DEV_ITEMS_OBJECTID,
				  BTRFS_DEV_ITEM_KEY);
	if (ret) {
		*devid_ret = 1;
	} else {
		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
				      path->slots[0]);
		*devid_ret = found_key.offset + 1;
	}
	ret = 0;
error:
	btrfs_free_path(path);
	return ret;
}

/*
 * the device information is stored in the chunk root
 * the btrfs_device struct should be fully filled in
 */
static int btrfs_add_device(struct btrfs_trans_handle *trans,
			    struct btrfs_root *root,
			    struct btrfs_device *device)
{
	int ret;
	struct btrfs_path *path;
	struct btrfs_dev_item *dev_item;
	struct extent_buffer *leaf;
	struct btrfs_key key;
	unsigned long ptr;

	root = root->fs_info->chunk_root;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
	key.type = BTRFS_DEV_ITEM_KEY;
	key.offset = device->devid;

	ret = btrfs_insert_empty_item(trans, root, path, &key,
				      sizeof(*dev_item));
	if (ret)
		goto out;

	leaf = path->nodes[0];
	dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);

	btrfs_set_device_id(leaf, dev_item, device->devid);
	btrfs_set_device_generation(leaf, dev_item, 0);
	btrfs_set_device_type(leaf, dev_item, device->type);
	btrfs_set_device_io_align(leaf, dev_item, device->io_align);
	btrfs_set_device_io_width(leaf, dev_item, device->io_width);
	btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
	btrfs_set_device_total_bytes(leaf, dev_item,
				     btrfs_device_get_disk_total_bytes(device));
	btrfs_set_device_bytes_used(leaf, dev_item,
				    btrfs_device_get_bytes_used(device));
	btrfs_set_device_group(leaf, dev_item, 0);
	btrfs_set_device_seek_speed(leaf, dev_item, 0);
	btrfs_set_device_bandwidth(leaf, dev_item, 0);
	btrfs_set_device_start_offset(leaf, dev_item, 0);

	ptr = btrfs_device_uuid(dev_item);
	write_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
	ptr = btrfs_device_fsid(dev_item);
	write_extent_buffer(leaf, root->fs_info->fsid, ptr, BTRFS_UUID_SIZE);
	btrfs_mark_buffer_dirty(leaf);

	ret = 0;
out:
	btrfs_free_path(path);
	return ret;
}

/*
 * Function to update ctime/mtime for a given device path.
 * Mainly used for ctime/mtime based probe like libblkid.
 */
static void update_dev_time(char *path_name)
{
	struct file *filp;

	filp = filp_open(path_name, O_RDWR, 0);
	if (IS_ERR(filp))
		return;
	file_update_time(filp);
	filp_close(filp, NULL);
	return;
}

static int btrfs_rm_dev_item(struct btrfs_root *root,
			     struct btrfs_device *device)
{
	int ret;
	struct btrfs_path *path;
	struct btrfs_key key;
	struct btrfs_trans_handle *trans;

	root = root->fs_info->chunk_root;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	trans = btrfs_start_transaction(root, 0);
	if (IS_ERR(trans)) {
		btrfs_free_path(path);
		return PTR_ERR(trans);
	}
	key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
	key.type = BTRFS_DEV_ITEM_KEY;
	key.offset = device->devid;

	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
	if (ret < 0)
		goto out;

	if (ret > 0) {
		ret = -ENOENT;
		goto out;
	}

	ret = btrfs_del_item(trans, root, path);
	if (ret)
		goto out;
out:
	btrfs_free_path(path);
	btrfs_commit_transaction(trans, root);
	return ret;
}

int btrfs_rm_device(struct btrfs_root *root, char *device_path)
{
	struct btrfs_device *device;
	struct btrfs_device *next_device;
	struct block_device *bdev;
	struct buffer_head *bh = NULL;
	struct btrfs_super_block *disk_super;
	struct btrfs_fs_devices *cur_devices;
	u64 all_avail;
	u64 devid;
	u64 num_devices;
	u8 *dev_uuid;
	unsigned seq;
	int ret = 0;
	bool clear_super = false;

	mutex_lock(&uuid_mutex);

	do {
		seq = read_seqbegin(&root->fs_info->profiles_lock);

		all_avail = root->fs_info->avail_data_alloc_bits |
			    root->fs_info->avail_system_alloc_bits |
			    root->fs_info->avail_metadata_alloc_bits;
	} while (read_seqretry(&root->fs_info->profiles_lock, seq));

	num_devices = root->fs_info->fs_devices->num_devices;
	btrfs_dev_replace_lock(&root->fs_info->dev_replace);
	if (btrfs_dev_replace_is_ongoing(&root->fs_info->dev_replace)) {
		WARN_ON(num_devices < 1);
		num_devices--;
	}
	btrfs_dev_replace_unlock(&root->fs_info->dev_replace);

	if ((all_avail & BTRFS_BLOCK_GROUP_RAID10) && num_devices <= 4) {
		ret = BTRFS_ERROR_DEV_RAID10_MIN_NOT_MET;
		goto out;
	}

	if ((all_avail & BTRFS_BLOCK_GROUP_RAID1) && num_devices <= 2) {
		ret = BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET;
		goto out;
	}

	if ((all_avail & BTRFS_BLOCK_GROUP_RAID5) &&
	    root->fs_info->fs_devices->rw_devices <= 2) {
		ret = BTRFS_ERROR_DEV_RAID5_MIN_NOT_MET;
		goto out;
	}
	if ((all_avail & BTRFS_BLOCK_GROUP_RAID6) &&
	    root->fs_info->fs_devices->rw_devices <= 3) {
		ret = BTRFS_ERROR_DEV_RAID6_MIN_NOT_MET;
		goto out;
	}

	if (strcmp(device_path, "missing") == 0) {
		struct list_head *devices;
		struct btrfs_device *tmp;

		device = NULL;
		devices = &root->fs_info->fs_devices->devices;
		/*
		 * It is safe to read the devices since the volume_mutex
		 * is held.
		 */
		list_for_each_entry(tmp, devices, dev_list) {
			if (tmp->in_fs_metadata &&
			    !tmp->is_tgtdev_for_dev_replace &&
			    !tmp->bdev) {
				device = tmp;
				break;
			}
		}
		bdev = NULL;
		bh = NULL;
		disk_super = NULL;
		if (!device) {
			ret = BTRFS_ERROR_DEV_MISSING_NOT_FOUND;
			goto out;
		}
	} else {
		ret = btrfs_get_bdev_and_sb(device_path,
					    FMODE_WRITE | FMODE_EXCL,
					    root->fs_info->bdev_holder, 0,
					    &bdev, &bh);
		if (ret)
			goto out;
		disk_super = (struct btrfs_super_block *)bh->b_data;
		devid = btrfs_stack_device_id(&disk_super->dev_item);
		dev_uuid = disk_super->dev_item.uuid;
		device = btrfs_find_device(root->fs_info, devid, dev_uuid,
					   disk_super->fsid);
		if (!device) {
			ret = -ENOENT;
			goto error_brelse;
		}
	}

	if (device->is_tgtdev_for_dev_replace) {
		ret = BTRFS_ERROR_DEV_TGT_REPLACE;
		goto error_brelse;
	}

	if (device->writeable && root->fs_info->fs_devices->rw_devices == 1) {
		ret = BTRFS_ERROR_DEV_ONLY_WRITABLE;
		goto error_brelse;
	}

	if (device->writeable) {
		lock_chunks(root);
		list_del_init(&device->dev_alloc_list);
		device->fs_devices->rw_devices--;
		unlock_chunks(root);
		clear_super = true;
	}

	mutex_unlock(&uuid_mutex);
	ret = btrfs_shrink_device(device, 0);
	mutex_lock(&uuid_mutex);
	if (ret)
		goto error_undo;

	/*
	 * TODO: the superblock still includes this device in its num_devices
	 * counter although write_all_supers() is not locked out. This
	 * could give a filesystem state which requires a degraded mount.
	 */
	ret = btrfs_rm_dev_item(root->fs_info->chunk_root, device);
	if (ret)
		goto error_undo;

	device->in_fs_metadata = 0;
	btrfs_scrub_cancel_dev(root->fs_info, device);

	/*
	 * the device list mutex makes sure that we don't change
	 * the device list while someone else is writing out all
	 * the device supers. Whoever is writing all supers, should
	 * lock the device list mutex before getting the number of
	 * devices in the super block (super_copy). Conversely,
	 * whoever updates the number of devices in the super block
	 * (super_copy) should hold the device list mutex.
	 */

	cur_devices = device->fs_devices;
	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
	list_del_rcu(&device->dev_list);

	device->fs_devices->num_devices--;
	device->fs_devices->total_devices--;

	if (device->missing)
		device->fs_devices->missing_devices--;

	next_device = list_entry(root->fs_info->fs_devices->devices.next,
				 struct btrfs_device, dev_list);
	if (device->bdev == root->fs_info->sb->s_bdev)
		root->fs_info->sb->s_bdev = next_device->bdev;
	if (device->bdev == root->fs_info->fs_devices->latest_bdev)
		root->fs_info->fs_devices->latest_bdev = next_device->bdev;

	if (device->bdev) {
		device->fs_devices->open_devices--;
		/* remove sysfs entry */
		btrfs_sysfs_rm_device_link(root->fs_info->fs_devices, device);
	}

	call_rcu(&device->rcu, free_device);

	num_devices = btrfs_super_num_devices(root->fs_info->super_copy) - 1;
	btrfs_set_super_num_devices(root->fs_info->super_copy, num_devices);
	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);

	if (cur_devices->open_devices == 0) {
		struct btrfs_fs_devices *fs_devices;
		fs_devices = root->fs_info->fs_devices;
		while (fs_devices) {
			if (fs_devices->seed == cur_devices) {
				fs_devices->seed = cur_devices->seed;
				break;
			}
			fs_devices = fs_devices->seed;
		}
		cur_devices->seed = NULL;
		__btrfs_close_devices(cur_devices);
		free_fs_devices(cur_devices);
	}

	root->fs_info->num_tolerated_disk_barrier_failures =
		btrfs_calc_num_tolerated_disk_barrier_failures(root->fs_info);

	/*
	 * at this point, the device is zero sized.  We want to
	 * remove it from the devices list and zero out the old super
	 */
	if (clear_super && disk_super) {
		u64 bytenr;
		int i;

		/* make sure this device isn't detected as part of
		 * the FS anymore
		 */
		memset(&disk_super->magic, 0, sizeof(disk_super->magic));
		set_buffer_dirty(bh);
		sync_dirty_buffer(bh);

		/* clear the mirror copies of super block on the disk
		 * being removed, 0th copy is been taken care above and
		 * the below would take of the rest
		 */
		for (i = 1; i < BTRFS_SUPER_MIRROR_MAX; i++) {
			bytenr = btrfs_sb_offset(i);
			if (bytenr + BTRFS_SUPER_INFO_SIZE >=
					i_size_read(bdev->bd_inode))
				break;

			brelse(bh);
			bh = __bread(bdev, bytenr / 4096,
					BTRFS_SUPER_INFO_SIZE);
			if (!bh)
				continue;

			disk_super = (struct btrfs_super_block *)bh->b_data;

			if (btrfs_super_bytenr(disk_super) != bytenr ||
				btrfs_super_magic(disk_super) != BTRFS_MAGIC) {
				continue;
			}
			memset(&disk_super->magic, 0,
						sizeof(disk_super->magic));
			set_buffer_dirty(bh);
			sync_dirty_buffer(bh);
		}
	}

	ret = 0;

	if (bdev) {
		/* Notify udev that device has changed */
		btrfs_kobject_uevent(bdev, KOBJ_CHANGE);

		/* Update ctime/mtime for device path for libblkid */
		update_dev_time(device_path);
	}

error_brelse:
	brelse(bh);
	if (bdev)
		blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
out:
	mutex_unlock(&uuid_mutex);
	return ret;
error_undo:
	if (device->writeable) {
		lock_chunks(root);
		list_add(&device->dev_alloc_list,
			 &root->fs_info->fs_devices->alloc_list);
		device->fs_devices->rw_devices++;
		unlock_chunks(root);
	}
	goto error_brelse;
}

void btrfs_rm_dev_replace_remove_srcdev(struct btrfs_fs_info *fs_info,
					struct btrfs_device *srcdev)
{
	struct btrfs_fs_devices *fs_devices;

	WARN_ON(!mutex_is_locked(&fs_info->fs_devices->device_list_mutex));

	/*
	 * in case of fs with no seed, srcdev->fs_devices will point
	 * to fs_devices of fs_info. However when the dev being replaced is
	 * a seed dev it will point to the seed's local fs_devices. In short
	 * srcdev will have its correct fs_devices in both the cases.
	 */
	fs_devices = srcdev->fs_devices;

	list_del_rcu(&srcdev->dev_list);
	list_del_rcu(&srcdev->dev_alloc_list);
	fs_devices->num_devices--;
	if (srcdev->missing)
		fs_devices->missing_devices--;

	if (srcdev->writeable) {
		fs_devices->rw_devices--;
		/* zero out the old super if it is writable */
		btrfs_scratch_superblocks(srcdev->bdev, srcdev->name->str);
	}

	if (srcdev->bdev)
		fs_devices->open_devices--;
}

void btrfs_rm_dev_replace_free_srcdev(struct btrfs_fs_info *fs_info,
				      struct btrfs_device *srcdev)
{
	struct btrfs_fs_devices *fs_devices = srcdev->fs_devices;

	call_rcu(&srcdev->rcu, free_device);

	/*
	 * unless fs_devices is seed fs, num_devices shouldn't go
	 * zero
	 */
	BUG_ON(!fs_devices->num_devices && !fs_devices->seeding);

	/* if this is no devs we rather delete the fs_devices */
	if (!fs_devices->num_devices) {
		struct btrfs_fs_devices *tmp_fs_devices;

		tmp_fs_devices = fs_info->fs_devices;
		while (tmp_fs_devices) {
			if (tmp_fs_devices->seed == fs_devices) {
				tmp_fs_devices->seed = fs_devices->seed;
				break;
			}
			tmp_fs_devices = tmp_fs_devices->seed;
		}
		fs_devices->seed = NULL;
		__btrfs_close_devices(fs_devices);
		free_fs_devices(fs_devices);
	}
}

void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
				      struct btrfs_device *tgtdev)
{
	struct btrfs_device *next_device;

	mutex_lock(&uuid_mutex);
	WARN_ON(!tgtdev);
	mutex_lock(&fs_info->fs_devices->device_list_mutex);

	btrfs_sysfs_rm_device_link(fs_info->fs_devices, tgtdev);

	if (tgtdev->bdev) {
		btrfs_scratch_superblocks(tgtdev->bdev, tgtdev->name->str);
		fs_info->fs_devices->open_devices--;
	}
	fs_info->fs_devices->num_devices--;

	next_device = list_entry(fs_info->fs_devices->devices.next,
				 struct btrfs_device, dev_list);
	if (tgtdev->bdev == fs_info->sb->s_bdev)
		fs_info->sb->s_bdev = next_device->bdev;
	if (tgtdev->bdev == fs_info->fs_devices->latest_bdev)
		fs_info->fs_devices->latest_bdev = next_device->bdev;
	list_del_rcu(&tgtdev->dev_list);

	call_rcu(&tgtdev->rcu, free_device);

	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
	mutex_unlock(&uuid_mutex);
}

static int btrfs_find_device_by_path(struct btrfs_root *root, char *device_path,
				     struct btrfs_device **device)
{
	int ret = 0;
	struct btrfs_super_block *disk_super;
	u64 devid;
	u8 *dev_uuid;
	struct block_device *bdev;
	struct buffer_head *bh;

	*device = NULL;
	ret = btrfs_get_bdev_and_sb(device_path, FMODE_READ,
				    root->fs_info->bdev_holder, 0, &bdev, &bh);
	if (ret)
		return ret;
	disk_super = (struct btrfs_super_block *)bh->b_data;
	devid = btrfs_stack_device_id(&disk_super->dev_item);
	dev_uuid = disk_super->dev_item.uuid;
	*device = btrfs_find_device(root->fs_info, devid, dev_uuid,
				    disk_super->fsid);
	brelse(bh);
	if (!*device)
		ret = -ENOENT;
	blkdev_put(bdev, FMODE_READ);
	return ret;
}

int btrfs_find_device_missing_or_by_path(struct btrfs_root *root,
					 char *device_path,
					 struct btrfs_device **device)
{
	*device = NULL;
	if (strcmp(device_path, "missing") == 0) {
		struct list_head *devices;
		struct btrfs_device *tmp;

		devices = &root->fs_info->fs_devices->devices;
		/*
		 * It is safe to read the devices since the volume_mutex
		 * is held by the caller.
		 */
		list_for_each_entry(tmp, devices, dev_list) {
			if (tmp->in_fs_metadata && !tmp->bdev) {
				*device = tmp;
				break;
			}
		}

		if (!*device)
			return BTRFS_ERROR_DEV_MISSING_NOT_FOUND;

		return 0;
	} else {
		return btrfs_find_device_by_path(root, device_path, device);
	}
}

/*
 * does all the dirty work required for changing file system's UUID.
 */
static int btrfs_prepare_sprout(struct btrfs_root *root)
{
	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
	struct btrfs_fs_devices *old_devices;
	struct btrfs_fs_devices *seed_devices;
	struct btrfs_super_block *disk_super = root->fs_info->super_copy;
	struct btrfs_device *device;
	u64 super_flags;

	BUG_ON(!mutex_is_locked(&uuid_mutex));
	if (!fs_devices->seeding)
		return -EINVAL;

	seed_devices = __alloc_fs_devices();
	if (IS_ERR(seed_devices))
		return PTR_ERR(seed_devices);

	old_devices = clone_fs_devices(fs_devices);
	if (IS_ERR(old_devices)) {
		kfree(seed_devices);
		return PTR_ERR(old_devices);
	}

	list_add(&old_devices->list, &fs_uuids);

	memcpy(seed_devices, fs_devices, sizeof(*seed_devices));
	seed_devices->opened = 1;
	INIT_LIST_HEAD(&seed_devices->devices);
	INIT_LIST_HEAD(&seed_devices->alloc_list);
	mutex_init(&seed_devices->device_list_mutex);

	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
	list_splice_init_rcu(&fs_devices->devices, &seed_devices->devices,
			      synchronize_rcu);
	list_for_each_entry(device, &seed_devices->devices, dev_list)
		device->fs_devices = seed_devices;

	lock_chunks(root);
	list_splice_init(&fs_devices->alloc_list, &seed_devices->alloc_list);
	unlock_chunks(root);

	fs_devices->seeding = 0;
	fs_devices->num_devices = 0;
	fs_devices->open_devices = 0;
	fs_devices->missing_devices = 0;
	fs_devices->rotating = 0;
	fs_devices->seed = seed_devices;

	generate_random_uuid(fs_devices->fsid);
	memcpy(root->fs_info->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
	memcpy(disk_super->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);

	super_flags = btrfs_super_flags(disk_super) &
		      ~BTRFS_SUPER_FLAG_SEEDING;
	btrfs_set_super_flags(disk_super, super_flags);

	return 0;
}

/*
 * strore the expected generation for seed devices in device items.
 */
static int btrfs_finish_sprout(struct btrfs_trans_handle *trans,
			       struct btrfs_root *root)
{
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	struct btrfs_dev_item *dev_item;
	struct btrfs_device *device;
	struct btrfs_key key;
	u8 fs_uuid[BTRFS_UUID_SIZE];
	u8 dev_uuid[BTRFS_UUID_SIZE];
	u64 devid;
	int ret;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	root = root->fs_info->chunk_root;
	key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
	key.offset = 0;
	key.type = BTRFS_DEV_ITEM_KEY;

	while (1) {
		ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
		if (ret < 0)
			goto error;

		leaf = path->nodes[0];
next_slot:
		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
			ret = btrfs_next_leaf(root, path);
			if (ret > 0)
				break;
			if (ret < 0)
				goto error;
			leaf = path->nodes[0];
			btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
			btrfs_release_path(path);
			continue;
		}

		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
		if (key.objectid != BTRFS_DEV_ITEMS_OBJECTID ||
		    key.type != BTRFS_DEV_ITEM_KEY)
			break;

		dev_item = btrfs_item_ptr(leaf, path->slots[0],
					  struct btrfs_dev_item);
		devid = btrfs_device_id(leaf, dev_item);
		read_extent_buffer(leaf, dev_uuid, btrfs_device_uuid(dev_item),
				   BTRFS_UUID_SIZE);
		read_extent_buffer(leaf, fs_uuid, btrfs_device_fsid(dev_item),
				   BTRFS_UUID_SIZE);
		device = btrfs_find_device(root->fs_info, devid, dev_uuid,
					   fs_uuid);
		BUG_ON(!device); /* Logic error */

		if (device->fs_devices->seeding) {
			btrfs_set_device_generation(leaf, dev_item,
						    device->generation);
			btrfs_mark_buffer_dirty(leaf);
		}

		path->slots[0]++;
		goto next_slot;
	}
	ret = 0;
error:
	btrfs_free_path(path);
	return ret;
}

int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
{
	struct request_queue *q;
	struct btrfs_trans_handle *trans;
	struct btrfs_device *device;
	struct block_device *bdev;
	struct list_head *devices;
	struct super_block *sb = root->fs_info->sb;
	struct rcu_string *name;
	u64 tmp;
	int seeding_dev = 0;
	int ret = 0;

	if ((sb->s_flags & MS_RDONLY) && !root->fs_info->fs_devices->seeding)
		return -EROFS;

	bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
				  root->fs_info->bdev_holder);
	if (IS_ERR(bdev))
		return PTR_ERR(bdev);

	if (root->fs_info->fs_devices->seeding) {
		seeding_dev = 1;
		down_write(&sb->s_umount);
		mutex_lock(&uuid_mutex);
	}

	filemap_write_and_wait(bdev->bd_inode->i_mapping);

	devices = &root->fs_info->fs_devices->devices;

	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
	list_for_each_entry(device, devices, dev_list) {
		if (device->bdev == bdev) {
			ret = -EEXIST;
			mutex_unlock(
				&root->fs_info->fs_devices->device_list_mutex);
			goto error;
		}
	}
	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);

	device = btrfs_alloc_device(root->fs_info, NULL, NULL);
	if (IS_ERR(device)) {
		/* we can safely leave the fs_devices entry around */
		ret = PTR_ERR(device);
		goto error;
	}

	name = rcu_string_strdup(device_path, GFP_NOFS);
	if (!name) {
		kfree(device);
		ret = -ENOMEM;
		goto error;
	}
	rcu_assign_pointer(device->name, name);

	trans = btrfs_start_transaction(root, 0);
	if (IS_ERR(trans)) {
		rcu_string_free(device->name);
		kfree(device);
		ret = PTR_ERR(trans);
		goto error;
	}

	q = bdev_get_queue(bdev);
	if (blk_queue_discard(q))
		device->can_discard = 1;
	device->writeable = 1;
	device->generation = trans->transid;
	device->io_width = root->sectorsize;
	device->io_align = root->sectorsize;
	device->sector_size = root->sectorsize;
	device->total_bytes = i_size_read(bdev->bd_inode);
	device->disk_total_bytes = device->total_bytes;
	device->commit_total_bytes = device->total_bytes;
	device->dev_root = root->fs_info->dev_root;
	device->bdev = bdev;
	device->in_fs_metadata = 1;
	device->is_tgtdev_for_dev_replace = 0;
	device->mode = FMODE_EXCL;
	device->dev_stats_valid = 1;
	set_blocksize(device->bdev, 4096);

	if (seeding_dev) {
		sb->s_flags &= ~MS_RDONLY;
		ret = btrfs_prepare_sprout(root);
		BUG_ON(ret); /* -ENOMEM */
	}

	device->fs_devices = root->fs_info->fs_devices;

	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
	lock_chunks(root);
	list_add_rcu(&device->dev_list, &root->fs_info->fs_devices->devices);
	list_add(&device->dev_alloc_list,
		 &root->fs_info->fs_devices->alloc_list);
	root->fs_info->fs_devices->num_devices++;
	root->fs_info->fs_devices->open_devices++;
	root->fs_info->fs_devices->rw_devices++;
	root->fs_info->fs_devices->total_devices++;
	root->fs_info->fs_devices->total_rw_bytes += device->total_bytes;

	spin_lock(&root->fs_info->free_chunk_lock);
	root->fs_info->free_chunk_space += device->total_bytes;
	spin_unlock(&root->fs_info->free_chunk_lock);

	if (!blk_queue_nonrot(bdev_get_queue(bdev)))
		root->fs_info->fs_devices->rotating = 1;

	tmp = btrfs_super_total_bytes(root->fs_info->super_copy);
	btrfs_set_super_total_bytes(root->fs_info->super_copy,
				    tmp + device->total_bytes);

	tmp = btrfs_super_num_devices(root->fs_info->super_copy);
	btrfs_set_super_num_devices(root->fs_info->super_copy,
				    tmp + 1);

	/* add sysfs device entry */
	btrfs_sysfs_add_device_link(root->fs_info->fs_devices, device);

	/*
	 * we've got more storage, clear any full flags on the space
	 * infos
	 */
	btrfs_clear_space_info_full(root->fs_info);

	unlock_chunks(root);
	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);

	if (seeding_dev) {
		lock_chunks(root);
		ret = init_first_rw_device(trans, root, device);
		unlock_chunks(root);
		if (ret) {
			btrfs_abort_transaction(trans, root, ret);
			goto error_trans;
		}
	}

	ret = btrfs_add_device(trans, root, device);
	if (ret) {
		btrfs_abort_transaction(trans, root, ret);
		goto error_trans;
	}

	if (seeding_dev) {
		char fsid_buf[BTRFS_UUID_UNPARSED_SIZE];

		ret = btrfs_finish_sprout(trans, root);
		if (ret) {
			btrfs_abort_transaction(trans, root, ret);
			goto error_trans;
		}

		/* Sprouting would change fsid of the mounted root,
		 * so rename the fsid on the sysfs
		 */
		snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU",
						root->fs_info->fsid);
		if (kobject_rename(&root->fs_info->fs_devices->fsid_kobj,
								fsid_buf))
			btrfs_warn(root->fs_info,
				"sysfs: failed to create fsid for sprout");
	}

	root->fs_info->num_tolerated_disk_barrier_failures =
		btrfs_calc_num_tolerated_disk_barrier_failures(root->fs_info);
	ret = btrfs_commit_transaction(trans, root);

	if (seeding_dev) {
		mutex_unlock(&uuid_mutex);
		up_write(&sb->s_umount);

		if (ret) /* transaction commit */
			return ret;

		ret = btrfs_relocate_sys_chunks(root);
		if (ret < 0)
			btrfs_std_error(root->fs_info, ret,
				    "Failed to relocate sys chunks after "
				    "device initialization. This can be fixed "
				    "using the \"btrfs balance\" command.");
		trans = btrfs_attach_transaction(root);
		if (IS_ERR(trans)) {
			if (PTR_ERR(trans) == -ENOENT)
				return 0;
			return PTR_ERR(trans);
		}
		ret = btrfs_commit_transaction(trans, root);
	}

	/* Update ctime/mtime for libblkid */
	update_dev_time(device_path);
	return ret;

error_trans:
	btrfs_end_transaction(trans, root);
	rcu_string_free(device->name);
	btrfs_sysfs_rm_device_link(root->fs_info->fs_devices, device);
	kfree(device);
error:
	blkdev_put(bdev, FMODE_EXCL);
	if (seeding_dev) {
		mutex_unlock(&uuid_mutex);
		up_write(&sb->s_umount);
	}
	return ret;
}

int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
				  struct btrfs_device *srcdev,
				  struct btrfs_device **device_out)
{
	struct request_queue *q;
	struct btrfs_device *device;
	struct block_device *bdev;
	struct btrfs_fs_info *fs_info = root->fs_info;
	struct list_head *devices;
	struct rcu_string *name;
	u64 devid = BTRFS_DEV_REPLACE_DEVID;
	int ret = 0;

	*device_out = NULL;
	if (fs_info->fs_devices->seeding) {
		btrfs_err(fs_info, "the filesystem is a seed filesystem!");
		return -EINVAL;
	}

	bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
				  fs_info->bdev_holder);
	if (IS_ERR(bdev)) {
		btrfs_err(fs_info, "target device %s is invalid!", device_path);
		return PTR_ERR(bdev);
	}

	filemap_write_and_wait(bdev->bd_inode->i_mapping);

	devices = &fs_info->fs_devices->devices;
	list_for_each_entry(device, devices, dev_list) {
		if (device->bdev == bdev) {
			btrfs_err(fs_info, "target device is in the filesystem!");
			ret = -EEXIST;
			goto error;
		}
	}


	if (i_size_read(bdev->bd_inode) <
	    btrfs_device_get_total_bytes(srcdev)) {
		btrfs_err(fs_info, "target device is smaller than source device!");
		ret = -EINVAL;
		goto error;
	}


	device = btrfs_alloc_device(NULL, &devid, NULL);
	if (IS_ERR(device)) {
		ret = PTR_ERR(device);
		goto error;
	}

	name = rcu_string_strdup(device_path, GFP_NOFS);
	if (!name) {
		kfree(device);
		ret = -ENOMEM;
		goto error;
	}
	rcu_assign_pointer(device->name, name);

	q = bdev_get_queue(bdev);
	if (blk_queue_discard(q))
		device->can_discard = 1;
	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
	device->writeable = 1;
	device->generation = 0;
	device->io_width = root->sectorsize;
	device->io_align = root->sectorsize;
	device->sector_size = root->sectorsize;
	device->total_bytes = btrfs_device_get_total_bytes(srcdev);
	device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
	device->bytes_used = btrfs_device_get_bytes_used(srcdev);
	ASSERT(list_empty(&srcdev->resized_list));
	device->commit_total_bytes = srcdev->commit_total_bytes;
	device->commit_bytes_used = device->bytes_used;
	device->dev_root = fs_info->dev_root;
	device->bdev = bdev;
	device->in_fs_metadata = 1;
	device->is_tgtdev_for_dev_replace = 1;
	device->mode = FMODE_EXCL;
	device->dev_stats_valid = 1;
	set_blocksize(device->bdev, 4096);
	device->fs_devices = fs_info->fs_devices;
	list_add(&device->dev_list, &fs_info->fs_devices->devices);
	fs_info->fs_devices->num_devices++;
	fs_info->fs_devices->open_devices++;
	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);

	*device_out = device;
	return ret;

error:
	blkdev_put(bdev, FMODE_EXCL);
	return ret;
}

void btrfs_init_dev_replace_tgtdev_for_resume(struct btrfs_fs_info *fs_info,
					      struct btrfs_device *tgtdev)
{
	WARN_ON(fs_info->fs_devices->rw_devices == 0);
	tgtdev->io_width = fs_info->dev_root->sectorsize;
	tgtdev->io_align = fs_info->dev_root->sectorsize;
	tgtdev->sector_size = fs_info->dev_root->sectorsize;
	tgtdev->dev_root = fs_info->dev_root;
	tgtdev->in_fs_metadata = 1;
}

static noinline int btrfs_update_device(struct btrfs_trans_handle *trans,
					struct btrfs_device *device)
{
	int ret;
	struct btrfs_path *path;
	struct btrfs_root *root;
	struct btrfs_dev_item *dev_item;
	struct extent_buffer *leaf;
	struct btrfs_key key;

	root = device->dev_root->fs_info->chunk_root;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
	key.type = BTRFS_DEV_ITEM_KEY;
	key.offset = device->devid;

	ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
	if (ret < 0)
		goto out;

	if (ret > 0) {
		ret = -ENOENT;
		goto out;
	}

	leaf = path->nodes[0];
	dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);

	btrfs_set_device_id(leaf, dev_item, device->devid);
	btrfs_set_device_type(leaf, dev_item, device->type);
	btrfs_set_device_io_align(leaf, dev_item, device->io_align);
	btrfs_set_device_io_width(leaf, dev_item, device->io_width);
	btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
	btrfs_set_device_total_bytes(leaf, dev_item,
				     btrfs_device_get_disk_total_bytes(device));
	btrfs_set_device_bytes_used(leaf, dev_item,
				    btrfs_device_get_bytes_used(device));
	btrfs_mark_buffer_dirty(leaf);

out:
	btrfs_free_path(path);
	return ret;
}

int btrfs_grow_device(struct btrfs_trans_handle *trans,
		      struct btrfs_device *device, u64 new_size)
{
	struct btrfs_super_block *super_copy =
		device->dev_root->fs_info->super_copy;
	struct btrfs_fs_devices *fs_devices;
	u64 old_total;
	u64 diff;

	if (!device->writeable)
		return -EACCES;

	lock_chunks(device->dev_root);
	old_total = btrfs_super_total_bytes(super_copy);
	diff = new_size - device->total_bytes;

	if (new_size <= device->total_bytes ||
	    device->is_tgtdev_for_dev_replace) {
		unlock_chunks(device->dev_root);
		return -EINVAL;
	}

	fs_devices = device->dev_root->fs_info->fs_devices;

	btrfs_set_super_total_bytes(super_copy, old_total + diff);
	device->fs_devices->total_rw_bytes += diff;

	btrfs_device_set_total_bytes(device, new_size);
	btrfs_device_set_disk_total_bytes(device, new_size);
	btrfs_clear_space_info_full(device->dev_root->fs_info);
	if (list_empty(&device->resized_list))
		list_add_tail(&device->resized_list,
			      &fs_devices->resized_devices);
	unlock_chunks(device->dev_root);

	return btrfs_update_device(trans, device);
}

static int btrfs_free_chunk(struct btrfs_trans_handle *trans,
			    struct btrfs_root *root, u64 chunk_objectid,
			    u64 chunk_offset)
{
	int ret;
	struct btrfs_path *path;
	struct btrfs_key key;

	root = root->fs_info->chunk_root;
	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	key.objectid = chunk_objectid;
	key.offset = chunk_offset;
	key.type = BTRFS_CHUNK_ITEM_KEY;

	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
	if (ret < 0)
		goto out;
	else if (ret > 0) { /* Logic error or corruption */
		btrfs_std_error(root->fs_info, -ENOENT,
			    "Failed lookup while freeing chunk.");
		ret = -ENOENT;
		goto out;
	}

	ret = btrfs_del_item(trans, root, path);
	if (ret < 0)
		btrfs_std_error(root->fs_info, ret,
			    "Failed to delete chunk item.");
out:
	btrfs_free_path(path);
	return ret;
}

static int btrfs_del_sys_chunk(struct btrfs_root *root, u64 chunk_objectid, u64
			chunk_offset)
{
	struct btrfs_super_block *super_copy = root->fs_info->super_copy;
	struct btrfs_disk_key *disk_key;
	struct btrfs_chunk *chunk;
	u8 *ptr;
	int ret = 0;
	u32 num_stripes;
	u32 array_size;
	u32 len = 0;
	u32 cur;
	struct btrfs_key key;

	lock_chunks(root);
	array_size = btrfs_super_sys_array_size(super_copy);

	ptr = super_copy->sys_chunk_array;
	cur = 0;

	while (cur < array_size) {
		disk_key = (struct btrfs_disk_key *)ptr;
		btrfs_disk_key_to_cpu(&key, disk_key);

		len = sizeof(*disk_key);

		if (key.type == BTRFS_CHUNK_ITEM_KEY) {
			chunk = (struct btrfs_chunk *)(ptr + len);
			num_stripes = btrfs_stack_chunk_num_stripes(chunk);
			len += btrfs_chunk_item_size(num_stripes);
		} else {
			ret = -EIO;
			break;
		}
		if (key.objectid == chunk_objectid &&
		    key.offset == chunk_offset) {
			memmove(ptr, ptr + len, array_size - (cur + len));
			array_size -= len;
			btrfs_set_super_sys_array_size(super_copy, array_size);
		} else {
			ptr += len;
			cur += len;
		}
	}
	unlock_chunks(root);
	return ret;
}

int btrfs_remove_chunk(struct btrfs_trans_handle *trans,
		       struct btrfs_root *root, u64 chunk_offset)
{
	struct extent_map_tree *em_tree;
	struct extent_map *em;
	struct btrfs_root *extent_root = root->fs_info->extent_root;
	struct map_lookup *map;
	u64 dev_extent_len = 0;
	u64 chunk_objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
	int i, ret = 0;

	/* Just in case */
	root = root->fs_info->chunk_root;
	em_tree = &root->fs_info->mapping_tree.map_tree;

	read_lock(&em_tree->lock);
	em = lookup_extent_mapping(em_tree, chunk_offset, 1);
	read_unlock(&em_tree->lock);

	if (!em || em->start > chunk_offset ||
	    em->start + em->len < chunk_offset) {
		/*
		 * This is a logic error, but we don't want to just rely on the
		 * user having built with ASSERT enabled, so if ASSERT doens't
		 * do anything we still error out.
		 */
		ASSERT(0);
		if (em)
			free_extent_map(em);
		return -EINVAL;
	}
	map = (struct map_lookup *)em->bdev;
	lock_chunks(root->fs_info->chunk_root);
	check_system_chunk(trans, extent_root, map->type);
	unlock_chunks(root->fs_info->chunk_root);

	for (i = 0; i < map->num_stripes; i++) {
		struct btrfs_device *device = map->stripes[i].dev;
		ret = btrfs_free_dev_extent(trans, device,
					    map->stripes[i].physical,
					    &dev_extent_len);
		if (ret) {
			btrfs_abort_transaction(trans, root, ret);
			goto out;
		}

		if (device->bytes_used > 0) {
			lock_chunks(root);
			btrfs_device_set_bytes_used(device,
					device->bytes_used - dev_extent_len);
			spin_lock(&root->fs_info->free_chunk_lock);
			root->fs_info->free_chunk_space += dev_extent_len;
			spin_unlock(&root->fs_info->free_chunk_lock);
			btrfs_clear_space_info_full(root->fs_info);
			unlock_chunks(root);
		}

		if (map->stripes[i].dev) {
			ret = btrfs_update_device(trans, map->stripes[i].dev);
			if (ret) {
				btrfs_abort_transaction(trans, root, ret);
				goto out;
			}
		}
	}
	ret = btrfs_free_chunk(trans, root, chunk_objectid, chunk_offset);
	if (ret) {
		btrfs_abort_transaction(trans, root, ret);
		goto out;
	}

	trace_btrfs_chunk_free(root, map, chunk_offset, em->len);

	if (map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
		ret = btrfs_del_sys_chunk(root, chunk_objectid, chunk_offset);
		if (ret) {
			btrfs_abort_transaction(trans, root, ret);
			goto out;
		}
	}

	ret = btrfs_remove_block_group(trans, extent_root, chunk_offset, em);
	if (ret) {
		btrfs_abort_transaction(trans, extent_root, ret);
		goto out;
	}

out:
	/* once for us */
	free_extent_map(em);
	return ret;
}

static int btrfs_relocate_chunk(struct btrfs_root *root, u64 chunk_offset)
{
	struct btrfs_root *extent_root;
	struct btrfs_trans_handle *trans;
	int ret;

	root = root->fs_info->chunk_root;
	extent_root = root->fs_info->extent_root;

	/*
	 * Prevent races with automatic removal of unused block groups.
	 * After we relocate and before we remove the chunk with offset
	 * chunk_offset, automatic removal of the block group can kick in,
	 * resulting in a failure when calling btrfs_remove_chunk() below.
	 *
	 * Make sure to acquire this mutex before doing a tree search (dev
	 * or chunk trees) to find chunks. Otherwise the cleaner kthread might
	 * call btrfs_remove_chunk() (through btrfs_delete_unused_bgs()) after
	 * we release the path used to search the chunk/dev tree and before
	 * the current task acquires this mutex and calls us.
	 */
	ASSERT(mutex_is_locked(&root->fs_info->delete_unused_bgs_mutex));

	ret = btrfs_can_relocate(extent_root, chunk_offset);
	if (ret)
		return -ENOSPC;

	/* step one, relocate all the extents inside this chunk */
	btrfs_scrub_pause(root);
	ret = btrfs_relocate_block_group(extent_root, chunk_offset);
	btrfs_scrub_continue(root);
	if (ret)
		return ret;

	trans = btrfs_start_trans_remove_block_group(root->fs_info,
						     chunk_offset);
	if (IS_ERR(trans)) {
		ret = PTR_ERR(trans);
		btrfs_std_error(root->fs_info, ret, NULL);
		return ret;
	}

	/*
	 * step two, delete the device extents and the
	 * chunk tree entries
	 */
	ret = btrfs_remove_chunk(trans, root, chunk_offset);
	btrfs_end_transaction(trans, root);
	return ret;
}

static int btrfs_relocate_sys_chunks(struct btrfs_root *root)
{
	struct btrfs_root *chunk_root = root->fs_info->chunk_root;
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	struct btrfs_chunk *chunk;
	struct btrfs_key key;
	struct btrfs_key found_key;
	u64 chunk_type;
	bool retried = false;
	int failed = 0;
	int ret;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

again:
	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
	key.offset = (u64)-1;
	key.type = BTRFS_CHUNK_ITEM_KEY;

	while (1) {
		mutex_lock(&root->fs_info->delete_unused_bgs_mutex);
		ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
		if (ret < 0) {
			mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
			goto error;
		}
		BUG_ON(ret == 0); /* Corruption */

		ret = btrfs_previous_item(chunk_root, path, key.objectid,
					  key.type);
		if (ret)
			mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);
		if (ret < 0)
			goto error;
		if (ret > 0)
			break;

		leaf = path->nodes[0];
		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);

		chunk = btrfs_item_ptr(leaf, path->slots[0],
				       struct btrfs_chunk);
		chunk_type = btrfs_chunk_type(leaf, chunk);
		btrfs_release_path(path);

		if (chunk_type & BTRFS_BLOCK_GROUP_SYSTEM) {
			ret = btrfs_relocate_chunk(chunk_root,
						   found_key.offset);
			if (ret == -ENOSPC)
				failed++;
			else
				BUG_ON(ret);
		}
		mutex_unlock(&root->fs_info->delete_unused_bgs_mutex);

		if (found_key.offset == 0)
			break;
		key.offset = found_key.offset - 1;
	}
	ret = 0;
	if (failed && !retried) {
		failed = 0;
		retried = true;
		goto again;
	} else if (WARN_ON(failed && retried)) {
		ret = -ENOSPC;
	}
error:
	btrfs_free_path(path);
	return ret;
}

static int insert_balance_item(struct btrfs_root *root,
			       struct btrfs_balance_control *bctl)
{
	struct btrfs_trans_handle *trans;
	struct btrfs_balance_item *item;
	struct btrfs_disk_balance_args disk_bargs;
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	struct btrfs_key key;
	int ret, err;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	trans = btrfs_start_transaction(root, 0);
	if (IS_ERR(trans)) {
		btrfs_free_path(path);
		return PTR_ERR(trans);
	}

	key.objectid = BTRFS_BALANCE_OBJECTID;
	key.type = BTRFS_BALANCE_ITEM_KEY;
	key.offset = 0;

	ret = btrfs_insert_empty_item(trans, root, path, &key,
				      sizeof(*item));
	if (ret)
		goto out;

	leaf = path->nodes[0];
	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_balance_item);

	memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));

	btrfs_cpu_balance_args_to_disk(&disk_bargs, &bctl->data);
	btrfs_set_balance_data(leaf, item, &disk_bargs);
	btrfs_cpu_balance_args_to_disk(&disk_bargs, &bctl->meta);
	btrfs_set_balance_meta(leaf, item, &disk_bargs);
	btrfs_cpu_balance_args_to_disk(&disk_bargs, &bctl->sys);
	btrfs_set_balance_sys(leaf, item, &disk_bargs);

	btrfs_set_balance_flags(leaf, item, bctl->flags);

	btrfs_mark_buffer_dirty(leaf);
out:
	btrfs_free_path(path);
	err = btrfs_commit_transaction(trans, root);
	if (err && !ret)
		ret = err;
	return ret;
}

static int del_balance_item(struct btrfs_root *root)
{
	struct btrfs_trans_handle *trans;
	struct btrfs_path *path;
	struct btrfs_key key;
	int ret, err;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	trans = btrfs_start_transaction(root, 0);
	if (IS_ERR(trans)) {
		btrfs_free_path(path);
		return PTR_ERR(trans);
	}

	key.objectid = BTRFS_BALANCE_OBJECTID;
	key.type = BTRFS_BALANCE_ITEM_KEY;
	key.offset = 0;

	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
	if (ret < 0)
		goto out;
	if (ret > 0) {
		ret = -ENOENT;
		goto out;
	}

	ret = btrfs_del_item(trans, root, path);
out:
	btrfs_free_path(path);
	err = btrfs_commit_transaction(trans, root);
	if (err && !ret)
		ret = err;
	return ret;
}

/*
 * This is a heuristic used to reduce the number of chunks balanced on
 * resume after balance was interrupted.
 */
static void update_balance_args(struct btrfs_balance_control *bctl)
{
	/*
	 * Turn on soft mode for chunk types that were being converted.
	 */
	if (bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT)
		bctl->data.flags |= BTRFS_BALANCE_ARGS_SOFT;
	if (bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT)
		bctl->sys.flags |= BTRFS_BALANCE_ARGS_SOFT;
	if (bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT)
		bctl->meta.flags |= BTRFS_BALANCE_ARGS_SOFT;

	/*
	 * Turn on usage filter if is not already used.  The idea is
	 * that chunks that we have already balanced should be
	 * reasonably full.  Don't do it for chunks that are being
	 * converted - that will keep us from relocating unconverted
	 * (albeit full) chunks.
	 */
	if (!(bctl->data.flags & BTRFS_BALANCE_ARGS_USAGE) &&
	    !(bctl->data.flags & BTRFS_BALANCE_ARGS_USAGE_RANGE) &&
	    !(bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT)) {
		bctl->data.flags |= BTRFS_BALANCE_ARGS_USAGE;
		bctl->data.usage = 90;
	}
	if (!(bctl->sys.flags & BTRFS_BALANCE_ARGS_USAGE) &&
	    !(bctl->sys.flags & BTRFS_BALANCE_ARGS_USAGE_RANGE) &&
	    !(bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT)) {
		bctl->sys.flags |= BTRFS_BALANCE_ARGS_USAGE;
		bctl->sys.usage = 90;
	}
	if (!(bctl->meta.flags & BTRFS_BALANCE_ARGS_USAGE) &&
	    !(bctl->meta.flags & BTRFS_BALANCE_ARGS_USAGE_RANGE) &&
	    !(bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT)) {
		bctl->meta.flags |= BTRFS_BALANCE_ARGS_USAGE;
		bctl->meta.usage = 90;
	}
}

/*
 * Should be called with both balance and volume mutexes held to
 * serialize other volume operations (add_dev/rm_dev/resize) with
 * restriper.  Same goes for unset_balance_control.
 */
static void set_balance_control(struct btrfs_balance_control *bctl)
{
	struct btrfs_fs_info *fs_info = bctl->fs_info;

	BUG_ON(fs_info->balance_ctl);

	spin_lock(&fs_info->balance_lock);
	fs_info->balance_ctl = bctl;
	spin_unlock(&fs_info->balance_lock);
}

static