Re: [PATCH 01/12] btrfs: balance btree dirty pages and delayed items after a rename

[Anand Jain <anand.jain@oracle.com>]

On 5/31/22 20:36, fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> A rename operation modifies a subvolume's btree, to remove the old dir
> item, add the new dir item, remove an inode ref and add a new inode ref.
> It can also create the delayed inode for the inodes involved in the
> operation, and it creates two delayed dir index items, one to delete
> the old name and another one to add the new name.
> 
> However we are neither balancing the btree dirty pages nor the delayed
> items after a rename, which can result in accumulation of too many
> btree dirty pages and delayed items, specially if a task is doing a
> series of rename operations (for example it can happen for package
> installations/upgrades through the zypper tool).
> 
> So just call btrfs_btree_balance_dirty() after a rename, just like we
> do for every other system call that results on modifying a btree and
> adding delayed items.
> 


LGTM

Reviewed-by: Anand Jain <anand.jain@oracle.com>


> Signed-off-by: Filipe Manana <fdmanana@suse.com>
> ---
>   fs/btrfs/inode.c | 14 ++++++++++----
>   1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index ba913ea6f4d1..06d5bfa84d38 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -9546,15 +9546,21 @@ static int btrfs_rename2(struct user_namespace *mnt_userns, struct inode *old_di
>   			 struct dentry *old_dentry, struct inode *new_dir,
>   			 struct dentry *new_dentry, unsigned int flags)
>   {
> +	int ret;
> +
>   	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
>   		return -EINVAL;
>   
>   	if (flags & RENAME_EXCHANGE)
> -		return btrfs_rename_exchange(old_dir, old_dentry, new_dir,
> -					  new_dentry);
> +		ret = btrfs_rename_exchange(old_dir, old_dentry, new_dir,
> +					    new_dentry);
> +	else
> +		ret = btrfs_rename(mnt_userns, old_dir, old_dentry, new_dir,
> +				   new_dentry, flags);
>   
> -	return btrfs_rename(mnt_userns, old_dir, old_dentry, new_dir,
> -			    new_dentry, flags);
> +	btrfs_btree_balance_dirty(BTRFS_I(new_dir)->root->fs_info);
> +
> +	return ret;
>   }
>   
>   struct btrfs_delalloc_work {