Re: [PATCH 08/15] xfs: move in-memory buftarg handling out of _xfs_buf_ioapply

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Jan 06, 2025 at 10:54:45AM +0100, Christoph Hellwig wrote:
> No I/O to apply for in-memory buffers, so skip the function call
> entirely.  Clean up the b_io_error initialization logic to allow
> for this.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Nice cleanup!
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_buf.c | 20 +++++++++-----------
>  1 file changed, 9 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index 18e830c4e990..e886605b5721 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1607,12 +1607,6 @@ _xfs_buf_ioapply(
>  	int		size;
>  	int		i;
>  
> -	/*
> -	 * Make sure we capture only current IO errors rather than stale errors
> -	 * left over from previous use of the buffer (e.g. failed readahead).
> -	 */
> -	bp->b_error = 0;
> -
>  	if (bp->b_flags & XBF_WRITE) {
>  		op = REQ_OP_WRITE;
>  	} else {
> @@ -1624,10 +1618,6 @@ _xfs_buf_ioapply(
>  	/* we only use the buffer cache for meta-data */
>  	op |= REQ_META;
>  
> -	/* in-memory targets are directly mapped, no IO required. */
> -	if (xfs_buftarg_is_mem(bp->b_target))
> -		return;
> -
>  	/*
>  	 * Walk all the vectors issuing IO on them. Set up the initial offset
>  	 * into the buffer and the desired IO size before we start -
> @@ -1740,7 +1730,11 @@ xfs_buf_submit(
>  	if (bp->b_flags & XBF_WRITE)
>  		xfs_buf_wait_unpin(bp);
>  
> -	/* clear the internal error state to avoid spurious errors */
> +	/*
> +	 * Make sure we capture only current IO errors rather than stale errors
> +	 * left over from previous use of the buffer (e.g. failed readahead).
> +	 */
> +	bp->b_error = 0;
>  	bp->b_io_error = 0;
>  
>  	/*
> @@ -1757,6 +1751,10 @@ xfs_buf_submit(
>  		goto done;
>  	}
>  
> +	/* In-memory targets are directly mapped, no I/O required. */
> +	if (xfs_buftarg_is_mem(bp->b_target))
> +		goto done;
> +
>  	_xfs_buf_ioapply(bp);
>  
>  done:
> -- 
> 2.45.2
> 
>