Re: [PATCH] btrfs: Merge inode_can_compress in inode_need_compress

[David Sterba <dsterba@suse.cz>]

On Tue, Aug 18, 2020 at 09:30:56AM +0300, Nikolay Borisov wrote:
> The latter is the only caller of the former. Just open code can_compress
> into need_compress and also remove the warning since it's made redundant
> by this change.
> 
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---
>  fs/btrfs/inode.c | 21 +++------------------
>  1 file changed, 3 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 15dc8b6871ac..19e1918bad5c 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -410,17 +410,6 @@ static noinline int add_async_extent(struct async_chunk *cow,
>  	return 0;
>  }
>  
> -/*
> - * Check if the inode has flags compatible with compression
> - */
> -static inline bool inode_can_compress(struct btrfs_inode *inode)
> -{
> -	if (inode->flags & BTRFS_INODE_NODATACOW ||
> -	    inode->flags & BTRFS_INODE_NODATASUM)
> -		return false;
> -	return true;
> -}
> -
>  /*
>   * Check if the inode needs to be submitted to compression, based on mount
>   * options, defragmentation, properties or heuristics.
> @@ -430,12 +419,9 @@ static inline int inode_need_compress(struct btrfs_inode *inode, u64 start,
>  {
>  	struct btrfs_fs_info *fs_info = inode->root->fs_info;
>  
> -	if (!inode_can_compress(inode)) {
> -		WARN(IS_ENABLED(CONFIG_BTRFS_DEBUG),
> -			KERN_ERR "BTRFS: unexpected compression for ino %llu\n",
> -			btrfs_ino(inode));
> +	if (inode->flags & BTRFS_INODE_NODATACOW ||
> +	    inode->flags & BTRFS_INODE_NODATASUM)
>  		return 0;

This serves as a runtime friendly assert, when inode_need_compress is
called from compress_file_range.

First call in btrfs_run_delalloc_range duplicates the
nodatacow/nodatasum which would be cleaned up by this patch but we'd
lose the warning in case compress_file_range detects the unexpected
flags.