btrfs: properly track when rescan worker is running (d2c609b8) · Commits · 戴 / test

The qgroup_flags field is overloaded such that it reflects the on-disk status of qgroups and the runtime state. The BTRFS_QGROUP_STATUS_FLAG_RESCAN flag is used to indicate that a rescan operation is in progress, but if the file system is unmounted while a rescan is running, the rescan operation is paused. If the file system is then mounted read-only, the flag will still be present but the rescan operation will not have been resumed. When we go to umount, btrfs_qgroup_wait_for_completion will see the flag and interpret it to mean that the rescan worker is still running and will wait for a completion that will never come. This patch uses a separate flag to indicate when the worker is running. The locking and state surrounding the qgroup rescan worker needs a lot of attention beyond this patch but this is enough to avoid a hung umount. Cc: <stable@vger.kernel.org> # v4.4+ Signed-off-by; Jeff Mahoney <jeffm@suse.com> Reviewed-by:

Qu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by:

David Sterba <dsterba@suse.com> Signed-off-by:

Chris Mason <clm@fb.com>

fs/btrfs/ctree.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -1028,6 +1028,7 @@ struct btrfs_fs_info {
		struct btrfs_workqueue *qgroup_rescan_workers;
		struct completion qgroup_rescan_completion;
		struct btrfs_work qgroup_rescan_work;
		bool qgroup_rescan_running; /* protected by qgroup_rescan_lock */

		/* filesystem state */
		unsigned long fs_state;

fs/btrfs/disk-io.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -2304,6 +2304,7 @@ static void btrfs_init_qgroup(struct btrfs_fs_info *fs_info)
		fs_info->quota_enabled = 0;
		fs_info->pending_quota_state = 0;
		fs_info->qgroup_ulist = NULL;
		fs_info->qgroup_rescan_running = false;
		mutex_init(&fs_info->qgroup_rescan_lock);
		}

fs/btrfs/qgroup.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -2303,6 +2303,10 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
		int err = -ENOMEM;
		int ret = 0;

		mutex_lock(&fs_info->qgroup_rescan_lock);
		fs_info->qgroup_rescan_running = true;
		mutex_unlock(&fs_info->qgroup_rescan_lock);

		path = btrfs_alloc_path();
		if (!path)
		goto out;
		@@ -2369,6 +2373,9 @@ out:
		}

		done:
		mutex_lock(&fs_info->qgroup_rescan_lock);
		fs_info->qgroup_rescan_running = false;
		mutex_unlock(&fs_info->qgroup_rescan_lock);
		complete_all(&fs_info->qgroup_rescan_completion);
		}

		@@ -2494,7 +2501,7 @@ int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info)

		mutex_lock(&fs_info->qgroup_rescan_lock);
		spin_lock(&fs_info->qgroup_lock);
		running = fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN;
		running = fs_info->qgroup_rescan_running;
		spin_unlock(&fs_info->qgroup_lock);
		mutex_unlock(&fs_info->qgroup_rescan_lock);

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