btrfs: fix fsfreeze hang caused by delayed iputs deal

[cascardo/linux.git] / fs / btrfs / super.c

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 864ce33..4071fe2 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2241,6 +2241,13 @@ static int btrfs_freeze(struct super_block *sb)
        struct btrfs_trans_handle *trans;
        struct btrfs_root *root = btrfs_sb(sb)->tree_root;
 
+       root->fs_info->fs_frozen = 1;
+       /*
+        * We don't need a barrier here, we'll wait for any transaction that
+        * could be in progress on other threads (and do delayed iputs that
+        * we want to avoid on a frozen filesystem), or do the commit
+        * ourselves.
+        */
        trans = btrfs_attach_transaction_barrier(root);
        if (IS_ERR(trans)) {
                /* no transaction, don't bother */
@@ -2251,6 +2258,14 @@ static int btrfs_freeze(struct super_block *sb)
        return btrfs_commit_transaction(trans, root);
 }
 
+static int btrfs_unfreeze(struct super_block *sb)
+{
+       struct btrfs_root *root = btrfs_sb(sb)->tree_root;
+
+       root->fs_info->fs_frozen = 0;
+       return 0;
+}
+
 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
 {
        struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
@@ -2299,6 +2314,7 @@ static const struct super_operations btrfs_super_ops = {
        .statfs         = btrfs_statfs,
        .remount_fs     = btrfs_remount,
        .freeze_fs      = btrfs_freeze,
+       .unfreeze_fs    = btrfs_unfreeze,
 };
 
 static const struct file_operations btrfs_ctl_fops = {