On 10.05.2018 09:21, Omar Sandoval wrote:
> From: Omar Sandoval <[email protected]>
> 
> btrfs_truncate_inode_items() uses two variables for error handling, ret
> and err. These are not handled consistently, leading to a couple of
> bugs.
> 
> - Errors from btrfs_del_items() are handled but not propagated to the
>   caller
> - If btrfs_run_delayed_refs() fails and aborts the transaction, we
>   continue running
> 
> Just use ret everywhere and simplify things a bit, fixing both of these
> issues.
> 
> Fixes: 79787eaab461 ("btrfs: replace many BUG_ONs with proper error handling")
> Fixes: 1262133b8d6f ("Btrfs: account for crcs in delayed ref processing")
> Signed-off-by: Omar Sandoval <[email protected]>

That function is horrendous so it needs much loving and this is a step
in the right direction.

LGTM:

Reviewed-by: Nikolay Borisov <[email protected]>

> ---
>  fs/btrfs/inode.c | 55 ++++++++++++++++++++++++------------------------
>  1 file changed, 28 insertions(+), 27 deletions(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index fef8dbb6a93f..79d1da01a90d 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -4442,7 +4442,6 @@ int btrfs_truncate_inode_items(struct 
> btrfs_trans_handle *trans,
>       int pending_del_slot = 0;
>       int extent_type = -1;
>       int ret;
> -     int err = 0;
>       u64 ino = btrfs_ino(BTRFS_I(inode));
>       u64 bytes_deleted = 0;
>       bool be_nice = false;
> @@ -4494,22 +4493,19 @@ int btrfs_truncate_inode_items(struct 
> btrfs_trans_handle *trans,
>        * up a huge file in a single leaf.  Most of the time that
>        * bytes_deleted is > 0, it will be huge by the time we get here
>        */
> -     if (be_nice && bytes_deleted > SZ_32M) {
> -             if (btrfs_should_end_transaction(trans)) {
> -                     err = -EAGAIN;
> -                     goto error;
> -             }
> +     if (be_nice && bytes_deleted > SZ_32M &&
> +         btrfs_should_end_transaction(trans)) {
> +             ret = -EAGAIN;
> +             goto out;
>       }
>  
> -
>       path->leave_spinning = 1;
>       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
> -     if (ret < 0) {
> -             err = ret;
> +     if (ret < 0)
>               goto out;
> -     }
>  
>       if (ret > 0) {
> +             ret = 0;
>               /* there are no items in the tree for us to truncate, we're
>                * done
>                */
> @@ -4620,7 +4616,7 @@ int btrfs_truncate_inode_items(struct 
> btrfs_trans_handle *trans,
>                                * We have to bail so the last_size is set to
>                                * just before this extent.
>                                */
> -                             err = NEED_TRUNCATE_BLOCK;
> +                             ret = NEED_TRUNCATE_BLOCK;
>                               break;
>                       }
>  
> @@ -4687,7 +4683,7 @@ int btrfs_truncate_inode_items(struct 
> btrfs_trans_handle *trans,
>                                               pending_del_nr);
>                               if (ret) {
>                                       btrfs_abort_transaction(trans, ret);
> -                                     goto error;
> +                                     break;
>                               }
>                               pending_del_nr = 0;
>                       }
> @@ -4698,8 +4694,8 @@ int btrfs_truncate_inode_items(struct 
> btrfs_trans_handle *trans,
>                                       trans->delayed_ref_updates = 0;
>                                       ret = btrfs_run_delayed_refs(trans,
>                                                                  updates * 2);
> -                                     if (ret && !err)
> -                                             err = ret;
> +                                     if (ret)
> +                                             break;
>                               }
>                       }
>                       /*
> @@ -4707,8 +4703,8 @@ int btrfs_truncate_inode_items(struct 
> btrfs_trans_handle *trans,
>                        * and let the transaction restart
>                        */
>                       if (should_end) {
> -                             err = -EAGAIN;
> -                             goto error;
> +                             ret = -EAGAIN;
> +                             break;
>                       }
>                       goto search_again;
>               } else {
> @@ -4716,32 +4712,37 @@ int btrfs_truncate_inode_items(struct 
> btrfs_trans_handle *trans,
>               }
>       }
>  out:
> -     if (pending_del_nr) {
> -             ret = btrfs_del_items(trans, root, path, pending_del_slot,
> +     if (ret >= 0 && pending_del_nr) {
> +             int err;
> +
> +             err = btrfs_del_items(trans, root, path, pending_del_slot,
>                                     pending_del_nr);
> -             if (ret)
> -                     btrfs_abort_transaction(trans, ret);
> +             if (err) {
> +                     btrfs_abort_transaction(trans, err);
> +                     ret = err;
> +             }
>       }
> -error:
>       if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
>               ASSERT(last_size >= new_size);
> -             if (!err && last_size > new_size)
> +             if (!ret && last_size > new_size)
>                       last_size = new_size;
>               btrfs_ordered_update_i_size(inode, last_size, NULL);
>       }
>  
>       btrfs_free_path(path);
>  
> -     if (be_nice && bytes_deleted > SZ_32M) {
> +     if (be_nice && bytes_deleted > SZ_32M && (ret >= 0 || ret == -EAGAIN)) {
>               unsigned long updates = trans->delayed_ref_updates;
> +             int err;
> +
>               if (updates) {
>                       trans->delayed_ref_updates = 0;
> -                     ret = btrfs_run_delayed_refs(trans, updates * 2);
> -                     if (ret && !err)
> -                             err = ret;
> +                     err = btrfs_run_delayed_refs(trans, updates * 2);
> +                     if (err)
> +                             ret = err;
>               }
>       }
> -     return err;
> +     return ret;
>  }
>  
>  /*
> 
--
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