Merge branch 'jeffm-discard-4.3' into for-linus-4.3

[karo-tx-linux.git] / fs / btrfs / super.c

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index d366dd4664d066269e9394403c060fece1a9100d..c389c13f0f383c4e086bb12045a47c4cfb343ef8 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -69,7 +69,7 @@ static struct file_system_type btrfs_fs_type;
 
 static int btrfs_remount(struct super_block *sb, int *flags, char *data);
 
-static const char *btrfs_decode_error(int errno)
+const char *btrfs_decode_error(int errno)
 {
        char *errstr = "unknown";
 
@@ -1651,6 +1651,17 @@ 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);