From: Jeff Mahoney <je...@suse.com>
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 <je...@suse.com>
---
fs/btrfs/disk-io.c | 9 +++++++++
fs/btrfs/super.c | 11 +++++++++++
2 files changed, 20 insertions(+)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 2ef9a4b..2e47fef 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3710,6 +3710,15 @@ void close_ctree(struct btrfs_root *root)
cancel_work_sync(&fs_info->async_reclaim_work);
if (!(fs_info->sb->s_flags & MS_RDONLY)) {
+ /*
+ * If the cleaner thread is stopped and there are
+ * block groups queued for removal, the deletion will be
+ * skipped when we quit the cleaner thread.
+ */
+ mutex_lock(&root->fs_info->cleaner_mutex);
+ btrfs_delete_unused_bgs(root->fs_info);
+ mutex_unlock(&root->fs_info->cleaner_mutex);
+
ret = btrfs_commit_super(root);
if (ret)
btrfs_err(fs_info, "commit super ret %d", ret);
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 9e66f5e..2ccd8d4 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1539,6 +1539,17 @@ static int btrfs_remount(struct super_block *sb, int
*flags, char *data)
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);
--
1.8.4.5
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