Re: [PATCH 1/2] btrfs: make the return value for log syncing consistent

[Filipe Manana <fdmanana@kernel.org>]

On Wed, Jun 01, 2022 at 11:16:24AM -0400, Josef Bacik wrote:
> Currently we will return 1 or -EAGAIN if we decide we need to commit
> the transaction rather than sync the log.  In practice this doesn't
> really matter, we interpret any !0 and !BTRFS_NO_LOG_SYNC as needing to
> commit the transaction.  However this makes it hard to figure out what
> the correct thing to do is.  Fix this up by defining
> BTRFS_LOG_FORCE_COMMIT and using this in all the places where we want to
> force the transaction to be committed.
> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> ---
>  fs/btrfs/tree-log.c | 18 +++++++++---------
>  fs/btrfs/tree-log.h |  3 +++
>  2 files changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> index 1201f083d4db..d898ba13285f 100644
> --- a/fs/btrfs/tree-log.c
> +++ b/fs/btrfs/tree-log.c
> @@ -171,7 +171,7 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
>  		int index = (root->log_transid + 1) % 2;
>  
>  		if (btrfs_need_log_full_commit(trans)) {
> -			ret = -EAGAIN;
> +			ret = BTRFS_LOG_FORCE_COMMIT;
>  			goto out;
>  		}
>  
> @@ -194,7 +194,7 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
>  		 * writing.
>  		 */
>  		if (zoned && !created) {
> -			ret = -EAGAIN;
> +			ret = BTRFS_LOG_FORCE_COMMIT;
>  			goto out;
>  		}
>  
> @@ -3121,7 +3121,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
>  
>  	/* bail out if we need to do a full commit */
>  	if (btrfs_need_log_full_commit(trans)) {
> -		ret = -EAGAIN;
> +		ret = BTRFS_LOG_FORCE_COMMIT;
>  		mutex_unlock(&root->log_mutex);
>  		goto out;
>  	}
> @@ -3222,7 +3222,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
>  		}
>  		btrfs_wait_tree_log_extents(log, mark);
>  		mutex_unlock(&log_root_tree->log_mutex);
> -		ret = -EAGAIN;
> +		ret = BTRFS_LOG_FORCE_COMMIT;
>  		goto out;
>  	}
>  
> @@ -3261,7 +3261,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
>  		blk_finish_plug(&plug);
>  		btrfs_wait_tree_log_extents(log, mark);
>  		mutex_unlock(&log_root_tree->log_mutex);
> -		ret = -EAGAIN;
> +		ret = BTRFS_LOG_FORCE_COMMIT;
>  		goto out_wake_log_root;
>  	}
>  
> @@ -5848,7 +5848,7 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
>  	    inode_only == LOG_INODE_ALL &&
>  	    inode->last_unlink_trans >= trans->transid) {
>  		btrfs_set_log_full_commit(trans);
> -		ret = 1;
> +		ret = BTRFS_LOG_FORCE_COMMIT;
>  		goto out_unlock;
>  	}
>  
> @@ -6562,12 +6562,12 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
>  	bool log_dentries = false;
>  
>  	if (btrfs_test_opt(fs_info, NOTREELOG)) {
> -		ret = 1;
> +		ret = BTRFS_LOG_FORCE_COMMIT;
>  		goto end_no_trans;
>  	}
>  
>  	if (btrfs_root_refs(&root->root_item) == 0) {
> -		ret = 1;
> +		ret = BTRFS_LOG_FORCE_COMMIT;
>  		goto end_no_trans;
>  	}
>  
> @@ -6665,7 +6665,7 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
>  end_trans:
>  	if (ret < 0) {
>  		btrfs_set_log_full_commit(trans);
> -		ret = 1;
> +		ret = BTRFS_LOG_FORCE_COMMIT;
>  	}
>  
>  	if (ret)
> diff --git a/fs/btrfs/tree-log.h b/fs/btrfs/tree-log.h
> index 1620f8170629..c3baa9d979a9 100644
> --- a/fs/btrfs/tree-log.h
> +++ b/fs/btrfs/tree-log.h
> @@ -12,6 +12,9 @@
>  /* return value for btrfs_log_dentry_safe that means we don't need to log it at all */
>  #define BTRFS_NO_LOG_SYNC 256
>  
> +/* we can't use the tree log for whatever reason, force a transaction commit */
> +#define BTRFS_LOG_FORCE_COMMIT 1

At btrfs_sync_file(), we shoudl also replace 1 with BTRFS_LOG_FORCE_COMMIT.
Otherwise it looks good, thanks.

> +
>  struct btrfs_log_ctx {
>  	int log_ret;
>  	int log_transid;
> -- 
> 2.26.3
>