Commit b382a324 authored by Jan Schmidt's avatar Jan Schmidt Committed by Josef Bacik
Browse files

Btrfs: fix qgroup rescan resume on mount 



When called during mount, we cannot start the rescan worker thread until
open_ctree is done. This commit restuctures the qgroup rescan internals to
enable a clean deferral of the rescan resume operation.

First of all, the struct qgroup_rescan is removed, saving us a malloc and
some initialization synchronizations problems. Its only element (the worker
struct) now lives within fs_info just as the rest of the rescan code.

Then setting up a rescan worker is split into several reusable stages.
Currently we have three different rescan startup scenarios:
	(A) rescan ioctl
	(B) rescan resume by mount
	(C) rescan by quota enable

Each case needs its own combination of the four following steps:
	(1) set the progress [A, C: zero; B: state of umount]
	(2) commit the transaction [A]
	(3) set the counters [A, C: zero; B: state of umount]
	(4) start worker [A, B, C]

qgroup_rescan_init does step (1). There's no extra function added to commit
a transaction, we've got that already. qgroup_rescan_zero_tracking does
step (3). Step (4) is nothing more than a call to the generic
btrfs_queue_worker.

We also get rid of a double check for the rescan progress during
btrfs_qgroup_account_ref, which is no longer required due to having step 2
from the list above.

As a side effect, this commit prepares to move the rescan start code from
btrfs_run_qgroups (which is run during commit) to a less time critical
section.

Signed-off-by: default avatarJan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
parent eb1716af

fs/btrfs/ctree.h

+2 −0
Original line number Diff line number Diff line
@@ -1609,6 +1609,7 @@ struct btrfs_fs_info { 
	struct btrfs_key qgroup_rescan_progress;

	struct btrfs_workers qgroup_rescan_workers;

	struct completion qgroup_rescan_completion;

	struct btrfs_work qgroup_rescan_work;



	/* filesystem state */

	unsigned long fs_state;
@@ -3858,6 +3859,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans, 
int btrfs_quota_disable(struct btrfs_trans_handle *trans,

			struct btrfs_fs_info *fs_info);

int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info);

void btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info);

int btrfs_qgroup_wait_for_completion(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);

fs/btrfs/disk-io.c

+2 −0
Original line number Diff line number Diff line
@@ -2879,6 +2879,8 @@ retry_root_backup: 
		return ret;

	}



	btrfs_qgroup_rescan_resume(fs_info);



	return 0;



fail_qgroup:

fs/btrfs/qgroup.c

+121 −69
Original line number Diff line number Diff line
@@ -98,13 +98,10 @@ 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);

static int

qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,

		   int init_flags);

static void qgroup_rescan_zero_tracking(struct btrfs_fs_info *fs_info);



/* must be called with qgroup_ioctl_lock held */

static struct btrfs_qgroup *find_qgroup_rb(struct btrfs_fs_info *fs_info,
@@ -255,6 +252,7 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info) 
	int slot;

	int ret = 0;

	u64 flags = 0;

	u64 rescan_progress = 0;



	if (!fs_info->quota_enabled)

		return 0;
@@ -312,20 +310,7 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info) 
			}

			fs_info->qgroup_flags = btrfs_qgroup_status_flags(l,

									  ptr);

			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);

			}

			rescan_progress = btrfs_qgroup_status_rescan(l, ptr);

			goto next1;

		}
@@ -427,12 +412,16 @@ out: 
	if (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON)) {

		fs_info->quota_enabled = 0;

		fs_info->pending_quota_state = 0;

	} else if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN &&

		   ret >= 0) {

		ret = qgroup_rescan_init(fs_info, rescan_progress, 0);

	}

	btrfs_free_path(path);



	if (ret < 0) {

		ulist_free(fs_info->qgroup_ulist);

		fs_info->qgroup_ulist = NULL;

		fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;

	}



	return ret < 0 ? ret : 0;
@@ -1449,14 +1438,7 @@ 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;

			goto unlock;

		}

	}



	quota_root = fs_info->quota_root;

	if (!quota_root)
@@ -1496,7 +1478,6 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle *trans, 


unlock:

	spin_unlock(&fs_info->qgroup_lock);

	mutex_unlock(&fs_info->qgroup_rescan_lock);

	ulist_free(roots);



	return ret;
@@ -1544,9 +1525,12 @@ int btrfs_run_qgroups(struct btrfs_trans_handle *trans, 
		fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;



	if (!ret && start_rescan_worker) {

		ret = btrfs_qgroup_rescan(fs_info);

		if (ret)

			pr_err("btrfs: start rescan quota failed: %d\n", ret);

		ret = qgroup_rescan_init(fs_info, 0, 1);

		if (!ret) {

			qgroup_rescan_zero_tracking(fs_info);

			btrfs_queue_worker(&fs_info->qgroup_rescan_workers,

					   &fs_info->qgroup_rescan_work);

		}

		ret = 0;

	}
@@ -1880,12 +1864,11 @@ void assert_qgroups_uptodate(struct btrfs_trans_handle *trans) 
 * 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,

qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, 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;
@@ -2013,11 +1996,10 @@ out: 


static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)

{

	struct qgroup_rescan *qscan = container_of(work, struct qgroup_rescan,

						   work);

	struct btrfs_fs_info *fs_info = container_of(work, struct btrfs_fs_info,

						     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;
@@ -2042,7 +2024,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work) 
		if (!fs_info->quota_enabled) {

			err = -EINTR;

		} else {

			err = qgroup_rescan_leaf(qscan, path, trans,

			err = qgroup_rescan_leaf(fs_info, path, trans,

						 tmp, scratch_leaf);

		}

		if (err > 0)
@@ -2055,7 +2037,6 @@ 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;
@@ -2078,46 +2059,70 @@ out: 
	complete_all(&fs_info->qgroup_rescan_completion);

}



static void

qgroup_rescan_start(struct btrfs_fs_info *fs_info, struct qgroup_rescan *qscan)

{

	memset(&qscan->work, 0, sizeof(qscan->work));

	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)

/*

 * Checks that (a) no rescan is running and (b) quota is enabled. Allocates all

 * memory required for the rescan context.

 */

static int

qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,

		   int init_flags)

{

	int ret = 0;

	struct rb_node *n;

	struct btrfs_qgroup *qgroup;

	struct qgroup_rescan *qscan = kmalloc(sizeof(*qscan), GFP_NOFS);



	if (!qscan)

		return -ENOMEM;

	if (!init_flags &&

	    (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) ||

	     !(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON))) {

		ret = -EINVAL;

		goto err;

	}



	mutex_lock(&fs_info->qgroup_rescan_lock);

	spin_lock(&fs_info->qgroup_lock);



	if (init_flags) {

		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;

			goto err;

		}



		fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN;

	}



	memset(&fs_info->qgroup_rescan_progress, 0,

		sizeof(fs_info->qgroup_rescan_progress));

	fs_info->qgroup_rescan_progress.objectid = progress_objectid;



	spin_unlock(&fs_info->qgroup_lock);

	mutex_unlock(&fs_info->qgroup_rescan_lock);



	init_completion(&fs_info->qgroup_rescan_completion);



	memset(&fs_info->qgroup_rescan_work, 0,

	       sizeof(fs_info->qgroup_rescan_work));

	fs_info->qgroup_rescan_work.func = btrfs_qgroup_rescan_worker;



	if (ret) {

err:

		pr_info("btrfs: qgroup_rescan_init failed with %d\n", ret);

		return ret;

	}



	return 0;

}



static void

qgroup_rescan_zero_tracking(struct btrfs_fs_info *fs_info)

{

	struct rb_node *n;

	struct btrfs_qgroup *qgroup;



	spin_lock(&fs_info->qgroup_lock);

	/* 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);
@@ -2127,9 +2132,44 @@ btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info) 
		qgroup->excl_cmpr = 0;

	}

	spin_unlock(&fs_info->qgroup_lock);

	mutex_unlock(&fs_info->qgroup_rescan_lock);

}



int

btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)

{

	int ret = 0;

	struct btrfs_trans_handle *trans;



	qgroup_rescan_start(fs_info, qscan);

	ret = qgroup_rescan_init(fs_info, 0, 1);

	if (ret)

		return ret;



	/*

	 * We have set the rescan_progress to 0, which means no more

	 * delayed refs will be accounted by btrfs_qgroup_account_ref.

	 * However, btrfs_qgroup_account_ref may be right after its call

	 * to btrfs_find_all_roots, in which case it would still do the

	 * accounting.

	 * To solve this, we're committing the transaction, which will

	 * ensure we run all delayed refs and only after that, we are

	 * going to clear all tracking information for a clean start.

	 */



	trans = btrfs_join_transaction(fs_info->fs_root);

	if (IS_ERR(trans)) {

		fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;

		return PTR_ERR(trans);

	}

	ret = btrfs_commit_transaction(trans, fs_info->fs_root);

	if (ret) {

		fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;

		return ret;

	}



	qgroup_rescan_zero_tracking(fs_info);



	btrfs_queue_worker(&fs_info->qgroup_rescan_workers,

			   &fs_info->qgroup_rescan_work);



	return 0;

}
@@ -2151,3 +2191,15 @@ int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info) 


	return ret;

}



/*

 * this is only called from open_ctree where we're still single threaded, thus

 * locking is omitted here.

 */

void

btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info)

{

	if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN)

		btrfs_queue_worker(&fs_info->qgroup_rescan_workers,

				   &fs_info->qgroup_rescan_work);

}

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