Re: [PATCH v2 2/3] Btrfs: rescan for qgroups

[Jan Schmidt <list.btrfs@jan-o-sch.net>]

On Tue, April 16, 2013 at 11:26 (+0200), Wang Shilong wrote:
> Hello, Jan
> 
>> If qgroup tracking is out of sync, a rescan operation can be started. It
>> iterates the complete extent tree and recalculates all qgroup tracking data.
>> This is an expensive operation and should not be used unless required.
>>
>> A filesystem under rescan can still be umounted. The rescan continues on the
>> next mount.  Status information is provided with a separate ioctl while a
>> rescan operation is in progress.
>>
>> Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
>> ---
>>  fs/btrfs/ctree.h           |   17 ++-
>>  fs/btrfs/disk-io.c         |    6 +
>>  fs/btrfs/ioctl.c           |   83 ++++++++++--
>>  fs/btrfs/qgroup.c          |  295 +++++++++++++++++++++++++++++++++++++++++--
>>  include/uapi/linux/btrfs.h |   12 ++-
>>  5 files changed, 378 insertions(+), 35 deletions(-)
>>
>> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
>> index 0d82922..bd4e2a7 100644
>> --- a/fs/btrfs/ctree.h
>> +++ b/fs/btrfs/ctree.h
>> @@ -1019,9 +1019,9 @@ struct btrfs_block_group_item {
>>   */
>>  #define BTRFS_QGROUP_STATUS_FLAG_ON		(1ULL << 0)
>>  /*
>> - * SCANNING is set during the initialization phase
>> + * RESCAN is set during the initialization phase
>>   */
>> -#define BTRFS_QGROUP_STATUS_FLAG_SCANNING	(1ULL << 1)
>> +#define BTRFS_QGROUP_STATUS_FLAG_RESCAN		(1ULL << 1)
>>  /*
>>   * Some qgroup entries are known to be out of date,
>>   * either because the configuration has changed in a way that
>> @@ -1050,7 +1050,7 @@ struct btrfs_qgroup_status_item {
>>  	 * only used during scanning to record the progress
>>  	 * of the scan. It contains a logical address
>>  	 */
>> -	__le64 scan;
>> +	__le64 rescan;
>>  } __attribute__ ((__packed__));
>>  
>>  struct btrfs_qgroup_info_item {
>> @@ -1587,6 +1587,11 @@ struct btrfs_fs_info {
>>  	/* used by btrfs_qgroup_record_ref for an efficient tree traversal */
>>  	u64 qgroup_seq;
>>  
>> +	/* qgroup rescan items */
>> +	struct mutex qgroup_rescan_lock; /* protects the progress item */
>> +	struct btrfs_key qgroup_rescan_progress;
>> +	struct btrfs_workers qgroup_rescan_workers;
>> +
>>  	/* filesystem state */
>>  	unsigned long fs_state;
>>  
>> @@ -2864,8 +2869,8 @@ BTRFS_SETGET_FUNCS(qgroup_status_version, struct btrfs_qgroup_status_item,
>>  		   version, 64);
>>  BTRFS_SETGET_FUNCS(qgroup_status_flags, struct btrfs_qgroup_status_item,
>>  		   flags, 64);
>> -BTRFS_SETGET_FUNCS(qgroup_status_scan, struct btrfs_qgroup_status_item,
>> -		   scan, 64);
>> +BTRFS_SETGET_FUNCS(qgroup_status_rescan, struct btrfs_qgroup_status_item,
>> +		   rescan, 64);
>>  
>>  /* btrfs_qgroup_info_item */
>>  BTRFS_SETGET_FUNCS(qgroup_info_generation, struct btrfs_qgroup_info_item,
>> @@ -3784,7 +3789,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
>>  		       struct btrfs_fs_info *fs_info);
>>  int btrfs_quota_disable(struct btrfs_trans_handle *trans,
>>  			struct btrfs_fs_info *fs_info);
>> -int btrfs_quota_rescan(struct btrfs_fs_info *fs_info);
>> +int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info);
>>  int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
>>  			      struct btrfs_fs_info *fs_info, u64 src, u64 dst);
>>  int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans,
>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
>> index 6d19a0a..60d15fe 100644
>> --- a/fs/btrfs/disk-io.c
>> +++ b/fs/btrfs/disk-io.c
>> @@ -2192,6 +2192,7 @@ int open_ctree(struct super_block *sb,
>>  	fs_info->qgroup_seq = 1;
>>  	fs_info->quota_enabled = 0;
>>  	fs_info->pending_quota_state = 0;
>> +	mutex_init(&fs_info->qgroup_rescan_lock);
>>  
>>  	btrfs_init_free_cluster(&fs_info->meta_alloc_cluster);
>>  	btrfs_init_free_cluster(&fs_info->data_alloc_cluster);
>> @@ -2394,6 +2395,8 @@ int open_ctree(struct super_block *sb,
>>  	btrfs_init_workers(&fs_info->readahead_workers, "readahead",
>>  			   fs_info->thread_pool_size,
>>  			   &fs_info->generic_worker);
>> +	btrfs_init_workers(&fs_info->qgroup_rescan_workers, "qgroup-rescan", 1,
>> +			   &fs_info->generic_worker);
>>  
>>  	/*
>>  	 * endios are largely parallel and should have a very
>> @@ -2428,6 +2431,7 @@ int open_ctree(struct super_block *sb,
>>  	ret |= btrfs_start_workers(&fs_info->caching_workers);
>>  	ret |= btrfs_start_workers(&fs_info->readahead_workers);
>>  	ret |= btrfs_start_workers(&fs_info->flush_workers);
>> +	ret |= btrfs_start_workers(&fs_info->qgroup_rescan_workers);
>>  	if (ret) {
>>  		err = -ENOMEM;
>>  		goto fail_sb_buffer;
>> @@ -2773,6 +2777,7 @@ fail_sb_buffer:
>>  	btrfs_stop_workers(&fs_info->delayed_workers);
>>  	btrfs_stop_workers(&fs_info->caching_workers);
>>  	btrfs_stop_workers(&fs_info->flush_workers);
>> +	btrfs_stop_workers(&fs_info->qgroup_rescan_workers);
>>  fail_alloc:
>>  fail_iput:
>>  	btrfs_mapping_tree_free(&fs_info->mapping_tree);
>> @@ -3463,6 +3468,7 @@ int close_ctree(struct btrfs_root *root)
>>  	btrfs_stop_workers(&fs_info->caching_workers);
>>  	btrfs_stop_workers(&fs_info->readahead_workers);
>>  	btrfs_stop_workers(&fs_info->flush_workers);
>> +	btrfs_stop_workers(&fs_info->qgroup_rescan_workers);
>>  
>>  #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
>>  	if (btrfs_test_opt(root, CHECK_INTEGRITY))
>> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>> index 898c572..17b53df 100644
>> --- a/fs/btrfs/ioctl.c
>> +++ b/fs/btrfs/ioctl.c
>> @@ -3693,12 +3693,10 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
>>  		goto drop_write;
>>  	}
>>  
>> -	if (sa->cmd != BTRFS_QUOTA_CTL_RESCAN) {
>> -		trans = btrfs_start_transaction(root, 2);
>> -		if (IS_ERR(trans)) {
>> -			ret = PTR_ERR(trans);
>> -			goto out;
>> -		}
>> +	trans = btrfs_start_transaction(root, 2);
>> +	if (IS_ERR(trans)) {
>> +		ret = PTR_ERR(trans);
>> +		goto out;
>>  	}
>>  
>>  	switch (sa->cmd) {
>> @@ -3708,9 +3706,6 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
>>  	case BTRFS_QUOTA_CTL_DISABLE:
>>  		ret = btrfs_quota_disable(trans, root->fs_info);
>>  		break;
>> -	case BTRFS_QUOTA_CTL_RESCAN:
>> -		ret = btrfs_quota_rescan(root->fs_info);
>> -		break;
>>  	default:
>>  		ret = -EINVAL;
>>  		break;
>> @@ -3719,11 +3714,9 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
>>  	if (copy_to_user(arg, sa, sizeof(*sa)))
>>  		ret = -EFAULT;
>>  
>> -	if (trans) {
>> -		err = btrfs_commit_transaction(trans, root);
>> -		if (err && !ret)
>> -			ret = err;
>> -	}
>> +	err = btrfs_commit_transaction(trans, root);
>> +	if (err && !ret)
>> +		ret = err;
>>  out:
>>  	kfree(sa);
>>  drop_write:
>> @@ -3877,6 +3870,64 @@ drop_write:
>>  	return ret;
>>  }
>>  
>> +static long btrfs_ioctl_quota_rescan(struct file *file, void __user *arg)
>> +{
>> +	struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
>> +	struct btrfs_ioctl_quota_rescan_args *qsa;
>> +	int ret;
>> +
>> +	if (!capable(CAP_SYS_ADMIN))
>> +		return -EPERM;
>> +
>> +	ret = mnt_want_write_file(file);
>> +	if (ret)
>> +		return ret;
>> +
>> +	qsa = memdup_user(arg, sizeof(*qsa));
>> +	if (IS_ERR(qsa)) {
>> +		ret = PTR_ERR(qsa);
>> +		goto drop_write;
>> +	}
>> +
>> +	if (qsa->flags) {
>> +		ret = -EINVAL;
>> +		goto out;
>> +	}
>> +
>> +	ret = btrfs_qgroup_rescan(root->fs_info);
>> +
>> +out:
>> +	kfree(qsa);
>> +drop_write:
>> +	mnt_drop_write_file(file);
>> +	return ret;
>> +}
>> +
>> +static long btrfs_ioctl_quota_rescan_status(struct file *file, void __user *arg)
>> +{
>> +	struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
>> +	struct btrfs_ioctl_quota_rescan_args *qsa;
>> +	int ret = 0;
>> +
>> +	if (!capable(CAP_SYS_ADMIN))
>> +		return -EPERM;
>> +
>> +	qsa = kzalloc(sizeof(*qsa), GFP_NOFS);
>> +	if (!qsa)
>> +		return -ENOMEM;
>> +
>> +	if (root->fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
>> +		qsa->flags = 1;
>> +		qsa->progress = root->fs_info->qgroup_rescan_progress.objectid;
>> +	}
>> +
>> +	if (copy_to_user(arg, qsa, sizeof(*qsa)))
>> +		ret = -EFAULT;
>> +
>> +	kfree(qsa);
>> +	return ret;
>> +}
>> +
>>  static long btrfs_ioctl_set_received_subvol(struct file *file,
>>  					    void __user *arg)
>>  {
>> @@ -4115,6 +4166,10 @@ long btrfs_ioctl(struct file *file, unsigned int
>>  		return btrfs_ioctl_qgroup_create(file, argp);
>>  	case BTRFS_IOC_QGROUP_LIMIT:
>>  		return btrfs_ioctl_qgroup_limit(file, argp);
>> +	case BTRFS_IOC_QUOTA_RESCAN:
>> +		return btrfs_ioctl_quota_rescan(file, argp);
>> +	case BTRFS_IOC_QUOTA_RESCAN_STATUS:
>> +		return btrfs_ioctl_quota_rescan_status(file, argp);
>>  	case BTRFS_IOC_DEV_REPLACE:
>>  		return btrfs_ioctl_dev_replace(root, argp);
>>  	case BTRFS_IOC_GET_FSLABEL:
>> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
>> index c38a0c5..bb081b5 100644
>> --- a/fs/btrfs/qgroup.c
>> +++ b/fs/btrfs/qgroup.c
>> @@ -31,13 +31,13 @@
>>  #include "locking.h"
>>  #include "ulist.h"
>>  #include "backref.h"
>> +#include "extent_io.h"
>>  
>>  /* TODO XXX FIXME
>>   *  - subvol delete -> delete when ref goes to 0? delete limits also?
>>   *  - reorganize keys
>>   *  - compressed
>>   *  - sync
>> - *  - rescan
>>   *  - copy also limits on subvol creation
>>   *  - limit
>>   *  - caches fuer ulists
>> @@ -98,6 +98,14 @@ struct btrfs_qgroup_list {
>>  	struct btrfs_qgroup *member;
>>  };
>>  
>> +struct qgroup_rescan {
>> +	struct btrfs_work	work;
>> +	struct btrfs_fs_info	*fs_info;
>> +};
>> +
>> +static void qgroup_rescan_start(struct btrfs_fs_info *fs_info,
>> +				struct qgroup_rescan *qscan);
>> +
>>  /* must be called with qgroup_lock held */
>>  static struct btrfs_qgroup *find_qgroup_rb(struct btrfs_fs_info *fs_info,
>>  					   u64 qgroupid)
>> @@ -298,7 +306,20 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info)
>>  			}
>>  			fs_info->qgroup_flags = btrfs_qgroup_status_flags(l,
>>  									  ptr);
>> -			/* FIXME read scan element */
>> +			fs_info->qgroup_rescan_progress.objectid =
>> +					btrfs_qgroup_status_rescan(l, ptr);
>> +			if (fs_info->qgroup_flags &
>> +			    BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
>> +				struct qgroup_rescan *qscan =
>> +					kmalloc(sizeof(*qscan), GFP_NOFS);
>> +				if (!qscan) {
>> +					ret = -ENOMEM;
>> +					goto out;
>> +				}
>> +				fs_info->qgroup_rescan_progress.type = 0;
>> +				fs_info->qgroup_rescan_progress.offset = 0;
>> +				qgroup_rescan_start(fs_info, qscan);
>> +			}
>>  			goto next1;
>>  		}
>>  
>> @@ -719,9 +740,12 @@ static int update_qgroup_status_item(struct btrfs_trans_handle *trans,
>>  	l = path->nodes[0];
>>  	slot = path->slots[0];
>>  	ptr = btrfs_item_ptr(l, slot, struct btrfs_qgroup_status_item);
>> +	spin_lock(&fs_info->qgroup_lock);
>>  	btrfs_set_qgroup_status_flags(l, ptr, fs_info->qgroup_flags);
>>  	btrfs_set_qgroup_status_generation(l, ptr, trans->transid);
>> -	/* XXX scan */
>> +	btrfs_set_qgroup_status_rescan(l, ptr,
>> +				fs_info->qgroup_rescan_progress.objectid);
>> +	spin_unlock(&fs_info->qgroup_lock);
>>  
>>  	btrfs_mark_buffer_dirty(l);
>>  
>> @@ -830,7 +854,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
>>  	fs_info->qgroup_flags = BTRFS_QGROUP_STATUS_FLAG_ON |
>>  				BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
>>  	btrfs_set_qgroup_status_flags(leaf, ptr, fs_info->qgroup_flags);
>> -	btrfs_set_qgroup_status_scan(leaf, ptr, 0);
>> +	btrfs_set_qgroup_status_rescan(leaf, ptr, 0);
>>  
>>  	btrfs_mark_buffer_dirty(leaf);
>>  
>> @@ -894,10 +918,11 @@ out:
>>  	return ret;
>>  }
>>  
>> -int btrfs_quota_rescan(struct btrfs_fs_info *fs_info)
>> +static void qgroup_dirty(struct btrfs_fs_info *fs_info,
>> +			 struct btrfs_qgroup *qgroup)
>>  {
>> -	/* FIXME */
>> -	return 0;
>> +	if (list_empty(&qgroup->dirty))
>> +		list_add(&qgroup->dirty, &fs_info->dirty_qgroups);
>>  }
>>  
>>  int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
>> @@ -1045,13 +1070,6 @@ unlock:
>>  	return ret;
>>  }
>>  
>> -static void qgroup_dirty(struct btrfs_fs_info *fs_info,
>> -			 struct btrfs_qgroup *qgroup)
>> -{
>> -	if (list_empty(&qgroup->dirty))
>> -		list_add(&qgroup->dirty, &fs_info->dirty_qgroups);
>> -}
>> -
>>  /*
>>   * btrfs_qgroup_record_ref is called when the ref is added or deleted. it puts
>>   * the modification into a list that's later used by btrfs_end_transaction to
>> @@ -1256,6 +1274,15 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle *trans,
>>  		BUG();
>>  	}
>>  
>> +	mutex_lock(&fs_info->qgroup_rescan_lock);
>> +	if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
>> +		if (fs_info->qgroup_rescan_progress.objectid <= node->bytenr) {
>> +			mutex_unlock(&fs_info->qgroup_rescan_lock);
>> +			return 0;
>> +		}
>> +	}
>> +	mutex_unlock(&fs_info->qgroup_rescan_lock);
>> +
>>  	/*
>>  	 * the delayed ref sequence number we pass depends on the direction of
>>  	 * the operation. for add operations, we pass (node->seq - 1) to skip
>> @@ -1269,7 +1296,17 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle *trans,
>>  	if (ret < 0)
>>  		return ret;
>>  
>> +	mutex_lock(&fs_info->qgroup_rescan_lock);
>>  	spin_lock(&fs_info->qgroup_lock);
>> +	if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
>> +		if (fs_info->qgroup_rescan_progress.objectid <= node->bytenr) {
>> +			ret = 0;
>> +			mutex_unlock(&fs_info->qgroup_rescan_lock);
>> +			goto unlock;
>> +		}
>> +	}
>> +	mutex_unlock(&fs_info->qgroup_rescan_lock);
>> +
>>  	quota_root = fs_info->quota_root;
>>  	if (!quota_root)
>>  		goto unlock;
>> @@ -1652,3 +1689,233 @@ void assert_qgroups_uptodate(struct btrfs_trans_handle *trans)
>>  		trans->delayed_ref_elem.seq);
>>  	BUG();
>>  }
>> +
>> +/*
>> + * returns < 0 on error, 0 when more leafs are to be scanned.
>> + * returns 1 when done, 2 when done and FLAG_INCONSISTENT was cleared.
>> + */
>> +static int
>> +qgroup_rescan_leaf(struct qgroup_rescan *qscan, struct btrfs_path *path,
>> +		   struct btrfs_trans_handle *trans, struct ulist *tmp,
>> +		   struct extent_buffer *scratch_leaf)
>> +{
>> +	struct btrfs_key found;
>> +	struct btrfs_fs_info *fs_info = qscan->fs_info;
>> +	struct ulist *roots = NULL;
>> +	struct ulist_node *unode;
>> +	struct ulist_iterator uiter;
>> +	struct seq_list tree_mod_seq_elem = {};
>> +	u64 seq;
>> +	int slot;
>> +	int ret;
>> +
>> +	path->leave_spinning = 1;
>> +	mutex_lock(&fs_info->qgroup_rescan_lock);
>> +	ret = btrfs_search_slot_for_read(fs_info->extent_root,
>> +					 &fs_info->qgroup_rescan_progress,
>> +					 path, 1, 0);
>> +
>> +	pr_debug("current progress key (%llu %u %llu), search_slot ret %d\n",
>> +		 (unsigned long long)fs_info->qgroup_rescan_progress.objectid,
>> +		 fs_info->qgroup_rescan_progress.type,
>> +		 (unsigned long long)fs_info->qgroup_rescan_progress.offset,
>> +		 ret);
>> +
>> +	if (ret) {
>> +		/*
>> +		 * The rescan is about to end, we will not be scanning any
>> +		 * further blocks. We cannot unset the RESCAN flag here, because
>> +		 * we want to commit the transaction if everything went well.
>> +		 * To make the live accounting work in this phase, we set our
>> +		 * scan progress pointer such that every real extent objectid
>> +		 * will be smaller.
>> +		 */
>> +		fs_info->qgroup_rescan_progress.objectid = (u64)-1;
>> +		btrfs_release_path(path);
>> +		mutex_unlock(&fs_info->qgroup_rescan_lock);
>> +		return ret;
>> +	}
>> +
>> +	btrfs_item_key_to_cpu(path->nodes[0], &found,
>> +			      btrfs_header_nritems(path->nodes[0]) - 1);
>> +	fs_info->qgroup_rescan_progress.objectid = found.objectid + 1;
>> +
>> +	btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
>> +	memcpy(scratch_leaf, path->nodes[0], sizeof(*scratch_leaf));
>> +	slot = path->slots[0];
>> +	btrfs_release_path(path);
>> +	mutex_unlock(&fs_info->qgroup_rescan_lock);
>> +
>> +	for (; slot < btrfs_header_nritems(scratch_leaf); ++slot) {
>> +		btrfs_item_key_to_cpu(scratch_leaf, &found, slot);
>> +		if (found.type != BTRFS_EXTENT_ITEM_KEY)
>> +			continue;
>> +		ret = btrfs_find_all_roots(trans, fs_info, found.objectid,
>> +					   tree_mod_seq_elem.seq, &roots);
>> +		if (ret < 0)
>> +			break;
> 
> 
> 	I have sent the patch to issue the double free that use the function
> 	btrfs_find_all_roots(). So here if btrfs_find_all_roots() fails, please
> 	do not ulist_free(roots) more.

I don't see where I'm calling ulist_free(roots) in the error path. One of us is
missing something :-)

>> +		spin_lock(&fs_info->qgroup_lock);
>> +		seq = fs_info->qgroup_seq;
>> +		fs_info->qgroup_seq += roots->nnodes + 1; /* max refcnt */
>> +
>> +		ulist_reinit(tmp);
>> +		ULIST_ITER_INIT(&uiter);
>> +		while ((unode = ulist_next(roots, &uiter))) {
>> +			struct btrfs_qgroup *qg;
>> +
>> +			qg = find_qgroup_rb(fs_info, unode->val);
>> +			if (!qg)
>> +				continue;
>> +
>> +			ulist_add(tmp, qg->qgroupid, (uintptr_t)qg, GFP_ATOMIC);
> 
> 
> For this patch, you forget to add the check about ulist_add(), ulist_add() may
> return -ENOMEM. In fact, i have sent the patch to fix this problem in qgroup.c before.
> So you don't need to change patch1, but you dose need to add the check in the patch2.

Thanks for noticing, I'll send a fix in a few days to leave room for more comments.

-Jan

>> +		}
>> +
>> +		/* this is similar to step 2 of btrfs_qgroup_account_ref */
>> +		ULIST_ITER_INIT(&uiter);
>> +		while ((unode = ulist_next(tmp, &uiter))) {
>> +			struct btrfs_qgroup *qg;
>> +			struct btrfs_qgroup_list *glist;
>> +
>> +			qg = (struct btrfs_qgroup *)(uintptr_t) unode->aux;
>> +			qg->rfer += found.offset;
>> +			qg->rfer_cmpr += found.offset;
>> +			WARN_ON(qg->tag >= seq);
>> +			WARN_ON(qg->refcnt >= seq);
>> +			if (qg->refcnt < seq)
>> +				qg->refcnt = seq + 1;
>> +			else
>> +				qg->refcnt = qg->refcnt + 1;
>> +			qgroup_dirty(fs_info, qg);
>> +
>> +			list_for_each_entry(glist, &qg->groups, next_group) {
>> +				ulist_add(tmp, glist->group->qgroupid,
>> +					  (uintptr_t)glist->group,
>> +					  GFP_ATOMIC);
>> +			}
>> +		}
>> +
>> +		qgroup_account_ref_step3(fs_info, roots, tmp, seq, -1,
>> +					 found.offset);
>> +
>> +		spin_unlock(&fs_info->qgroup_lock);
>> +		ulist_free(roots);
>> +	}
>> +
>> +	btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
>> +
>> +	return ret;
>> +}
>> +
>> +static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
>> +{
>> +	struct qgroup_rescan *qscan = container_of(work, struct qgroup_rescan,
>> +						   work);
>> +	struct btrfs_path *path;
>> +	struct btrfs_trans_handle *trans = NULL;
>> +	struct btrfs_fs_info *fs_info = qscan->fs_info;
>> +	struct ulist *tmp = NULL;
>> +	struct extent_buffer *scratch_leaf = NULL;
>> +	int err = -ENOMEM;
>> +
>> +	path = btrfs_alloc_path();
>> +	if (!path)
>> +		goto out;
>> +	tmp = ulist_alloc(GFP_NOFS);
>> +	if (!tmp)
>> +		goto out;
>> +	scratch_leaf = kmalloc(sizeof(*scratch_leaf), GFP_NOFS);
>> +	if (!scratch_leaf)
>> +		goto out;
>> +
>> +	err = 0;
>> +	while (!err) {
>> +		trans = btrfs_start_transaction(fs_info->fs_root, 0);
>> +		if (IS_ERR(trans)) {
>> +			err = PTR_ERR(trans);
>> +			break;
>> +		}
>> +		err = qgroup_rescan_leaf(qscan, path, trans, tmp, scratch_leaf);
>> +		if (err > 0)
>> +			btrfs_commit_transaction(trans, fs_info->fs_root);
>> +		else
>> +			btrfs_end_transaction(trans, fs_info->fs_root);
>> +	}
>> +
>> +out:
>> +	kfree(scratch_leaf);
>> +	ulist_free(tmp);
>> +	btrfs_free_path(path);
>> +	kfree(qscan);
>> +
>> +	mutex_lock(&fs_info->qgroup_rescan_lock);
>> +	fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
>> +
>> +	if (err == 2 &&
>> +	    fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT) {
>> +		fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
>> +	} else if (err < 0) {
>> +		fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
>> +	}
>> +	mutex_unlock(&fs_info->qgroup_rescan_lock);
>> +
>> +	if (err >= 0) {
>> +		pr_info("btrfs: qgroup scan completed%s\n",
>> +			err == 2 ? " (inconsistency flag cleared)" : "");
>> +	} else {
>> +		pr_err("btrfs: qgroup scan failed with %d\n", err);
>> +	}
>> +}
>> +
>> +static void
>> +qgroup_rescan_start(struct btrfs_fs_info *fs_info, struct qgroup_rescan *qscan)
>> +{
>> +	qscan->work.func = btrfs_qgroup_rescan_worker;
>> +	qscan->fs_info = fs_info;
>> +
>> +	pr_info("btrfs: qgroup scan started\n");
>> +	btrfs_queue_worker(&fs_info->qgroup_rescan_workers, &qscan->work);
>> +}
>> +
>> +int
>> +btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)
>> +{
>> +	int ret = 0;
>> +	struct rb_node *n;
>> +	struct btrfs_qgroup *qgroup;
>> +	struct qgroup_rescan *qscan = kmalloc(sizeof(*qscan), GFP_NOFS);
>> +
>> +	if (!qscan)
>> +		return -ENOMEM;
>> +
>> +	mutex_lock(&fs_info->qgroup_rescan_lock);
>> +	spin_lock(&fs_info->qgroup_lock);
>> +	if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN)
>> +		ret = -EINPROGRESS;
>> +	else if (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON))
>> +		ret = -EINVAL;
>> +	if (ret) {
>> +		spin_unlock(&fs_info->qgroup_lock);
>> +		mutex_unlock(&fs_info->qgroup_rescan_lock);
>> +		kfree(qscan);
>> +		return ret;
>> +	}
>> +
>> +	fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN;
>> +	memset(&fs_info->qgroup_rescan_progress, 0,
>> +		sizeof(fs_info->qgroup_rescan_progress));
>> +
>> +	/* clear all current qgroup tracking information */
>> +	for (n = rb_first(&fs_info->qgroup_tree); n; n = rb_next(n)) {
>> +		qgroup = rb_entry(n, struct btrfs_qgroup, node);
>> +		qgroup->rfer = 0;
>> +		qgroup->rfer_cmpr = 0;
>> +		qgroup->excl = 0;
>> +		qgroup->excl_cmpr = 0;
>> +	}
>> +	spin_unlock(&fs_info->qgroup_lock);
>> +	mutex_unlock(&fs_info->qgroup_rescan_lock);
>> +
>> +	qgroup_rescan_start(fs_info, qscan);
>> +
>> +	return 0;
>> +}
>> diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
>> index fa3a5f9..ca70f08 100644
>> --- a/include/uapi/linux/btrfs.h
>> +++ b/include/uapi/linux/btrfs.h
>> @@ -376,12 +376,18 @@ struct btrfs_ioctl_get_dev_stats {
>>  
>>  #define BTRFS_QUOTA_CTL_ENABLE	1
>>  #define BTRFS_QUOTA_CTL_DISABLE	2
>> -#define BTRFS_QUOTA_CTL_RESCAN	3
>> +#define BTRFS_QUOTA_CTL_RESCAN__NOTUSED	3
>>  struct btrfs_ioctl_quota_ctl_args {
>>  	__u64 cmd;
>>  	__u64 status;
>>  };
>>  
>> +struct btrfs_ioctl_quota_rescan_args {
>> +	__u64	flags;
>> +	__u64   progress;
>> +	__u64   reserved[6];
>> +};
>> +
>>  struct btrfs_ioctl_qgroup_assign_args {
>>  	__u64 assign;
>>  	__u64 src;
>> @@ -502,6 +508,10 @@ struct btrfs_ioctl_send_args {
>>  			       struct btrfs_ioctl_qgroup_create_args)
>>  #define BTRFS_IOC_QGROUP_LIMIT _IOR(BTRFS_IOCTL_MAGIC, 43, \
>>  			       struct btrfs_ioctl_qgroup_limit_args)
>> +#define BTRFS_IOC_QUOTA_RESCAN _IOW(BTRFS_IOCTL_MAGIC, 44, \
>> +			       struct btrfs_ioctl_quota_rescan_args)
>> +#define BTRFS_IOC_QUOTA_RESCAN_STATUS _IOR(BTRFS_IOCTL_MAGIC, 45, \
>> +			       struct btrfs_ioctl_quota_rescan_args)
>>  #define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \
>>  				   char[BTRFS_LABEL_SIZE])
>>  #define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 50, \
> 
> 
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>