On 08/25/2012 02:53 AM, Josef Bacik wrote:
> We can deadlock with freeze right now because we unconditionally start a
> transaction in our ->sync_fs() call. To fix this just check and see if we
> have a running transaction to commit. This saves us from the deadlock
> because at this point we'll have the umount sem for the sb so we're safe
> from freezes coming in after we've done our check. With this patch the
> freeze xfstests no longer deadlocks. Thanks,
>
Actually I have a same patch pending to send...
Anyway, I'm happy with the bug has been fixed.
Reviewed-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
> Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxxxx>
> ---
> V1->V2: got a little overzealous and cleaned up the ret thing without actually
> removing the now unused ret variable.
>
> fs/btrfs/super.c | 13 +++++++++----
> 1 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 7b65fe8..83d6f9f 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -838,7 +838,6 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
> struct btrfs_trans_handle *trans;
> struct btrfs_fs_info *fs_info = btrfs_sb(sb);
> struct btrfs_root *root = fs_info->tree_root;
> - int ret;
>
> trace_btrfs_sync_fs(wait);
>
> @@ -849,11 +848,17 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
>
> btrfs_wait_ordered_extents(root, 0, 0);
>
> - trans = btrfs_start_transaction(root, 0);
> + spin_lock(&fs_info->trans_lock);
> + if (!fs_info->running_transaction) {
> + spin_unlock(&fs_info->trans_lock);
> + return 0;
> + }
> + spin_unlock(&fs_info->trans_lock);
> +
> + trans = btrfs_join_transaction(root);
> if (IS_ERR(trans))
> return PTR_ERR(trans);
> - ret = btrfs_commit_transaction(trans, root);
> - return ret;
> + return btrfs_commit_transaction(trans, root);
> }
>
> static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
>
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