Adding upstream version 6.8.12.upstream/6.8.12upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 38 insertions, 16 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6b93fae74..8851ba7a1 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3722,15 +3722,43 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
 		goto drop_write;
 	}
 
-	down_write(&fs_info->subvol_sem);
-
 	switch (sa->cmd) {
 	case BTRFS_QUOTA_CTL_ENABLE:
 	case BTRFS_QUOTA_CTL_ENABLE_SIMPLE_QUOTA:
+		down_write(&fs_info->subvol_sem);
 		ret = btrfs_quota_enable(fs_info, sa);
+		up_write(&fs_info->subvol_sem);
 		break;
 	case BTRFS_QUOTA_CTL_DISABLE:
+		/*
+		 * Lock the cleaner mutex to prevent races with concurrent
+		 * relocation, because relocation may be building backrefs for
+		 * blocks of the quota root while we are deleting the root. This
+		 * is like dropping fs roots of deleted snapshots/subvolumes, we
+		 * need the same protection.
+		 *
+		 * This also prevents races between concurrent tasks trying to
+		 * disable quotas, because we will unlock and relock
+		 * qgroup_ioctl_lock across BTRFS_FS_QUOTA_ENABLED changes.
+		 *
+		 * We take this here because we have the dependency of
+		 *
+		 * inode_lock -> subvol_sem
+		 *
+		 * because of rename.  With relocation we can prealloc extents,
+		 * so that makes the dependency chain
+		 *
+		 * cleaner_mutex -> inode_lock -> subvol_sem
+		 *
+		 * so we must take the cleaner_mutex here before we take the
+		 * subvol_sem.  The deadlock can't actually happen, but this
+		 * quiets lockdep.
+		 */
+		mutex_lock(&fs_info->cleaner_mutex);
+		down_write(&fs_info->subvol_sem);
 		ret = btrfs_quota_disable(fs_info);
+		up_write(&fs_info->subvol_sem);
+		mutex_unlock(&fs_info->cleaner_mutex);
 		break;
 	default:
 		ret = -EINVAL;
@@ -3738,7 +3766,6 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
 	}
 
 	kfree(sa);
-	up_write(&fs_info->subvol_sem);
 drop_write:
 	mnt_drop_write_file(file);
 	return ret;
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 82d4559eb..cacc12d0f 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1342,16 +1342,10 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
 	lockdep_assert_held_write(&fs_info->subvol_sem);
 
 	/*
-	 * Lock the cleaner mutex to prevent races with concurrent relocation,
-	 * because relocation may be building backrefs for blocks of the quota
-	 * root while we are deleting the root. This is like dropping fs roots
-	 * of deleted snapshots/subvolumes, we need the same protection.
-	 *
-	 * This also prevents races between concurrent tasks trying to disable
-	 * quotas, because we will unlock and relock qgroup_ioctl_lock across
-	 * BTRFS_FS_QUOTA_ENABLED changes.
+	 * Relocation will mess with backrefs, so make sure we have the
+	 * cleaner_mutex held to protect us from relocate.
 	 */
-	mutex_lock(&fs_info->cleaner_mutex);
+	lockdep_assert_held(&fs_info->cleaner_mutex);
 
 	mutex_lock(&fs_info->qgroup_ioctl_lock);
 	if (!fs_info->quota_root)
@@ -1373,9 +1367,13 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
 	clear_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
 	btrfs_qgroup_wait_for_completion(fs_info, false);
 
+	/*
+	 * We have nothing held here and no trans handle, just return the error
+	 * if there is one.
+	 */
 	ret = flush_reservations(fs_info);
 	if (ret)
-		goto out_unlock_cleaner;
+		return ret;
 
 	/*
 	 * 1 For the root item
@@ -1439,9 +1437,6 @@ out:
 		btrfs_end_transaction(trans);
 	else if (trans)
 		ret = btrfs_commit_transaction(trans);
-out_unlock_cleaner:
-	mutex_unlock(&fs_info->cleaner_mutex);
-
 	return ret;
 }