btrfs: explictly delete unused block groups in close_ctree and ro-remount
The cleaner thread may already be sleeping by the time we enter
close_ctree. If that's the case, we'll skip removing any unused
block groups queued for removal, even during a normal umount.
They'll be cleaned up automatically at next mount, but users
expect a umount to be a clean synchronization point, especially
when used on thin-provisioned storage with -odiscard. We also
explicitly remove unused block groups in the ro-remount path
for the same reason.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Tested-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index cd7ef34..a1077e0 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1650,6 +1650,17 @@
sb->s_flags |= MS_RDONLY;
+ /*
+ * Setting MS_RDONLY will put the cleaner thread to
+ * sleep at the next loop if it's already active.
+ * If it's already asleep, we'll leave unused block
+ * groups on disk until we're mounted read-write again
+ * unless we clean them up here.
+ */
+ mutex_lock(&root->fs_info->cleaner_mutex);
+ btrfs_delete_unused_bgs(fs_info);
+ mutex_unlock(&root->fs_info->cleaner_mutex);
+
btrfs_dev_replace_suspend_for_unmount(fs_info);
btrfs_scrub_cancel(fs_info);
btrfs_pause_balance(fs_info);