Re: [PATCH 06/19] buffer: detect metadata write errors with buffer_write_io_error()

On Sat 01-08-26 18:00:50, Chao Shi wrote:
> Both places in this file that report a metadata write error to a caller do
> it by testing !buffer_uptodate() after waiting for the write.  That works
> only because the write completion handlers clear BH_Uptodate when the write
> fails, which is what this series is removing: a buffer whose write failed
> still holds the correct data, and saying otherwise makes callers rewrite,
> re-read or WARN over a buffer that was never wrong.
> 
> BH_Write_EIO is the flag that actually means "the last write of this buffer
> failed", and both handlers already set it via mark_buffer_write_io_error().
> Test that instead.
> 
> No behaviour change: today a failed write through bh_end_write() or
> bh_end_async_write() sets BH_Write_EIO and clears BH_Uptodate together, so
> the two tests agree.  They stop agreeing at the end of the series, and this
> one stays right.
> 
> In __sync_dirty_buffer() the flag also refers unambiguously to the write we
> just issued, because __bh_submit() clears it when it resubmits a buffer for
> write.
> 
> Signed-off-by: Chao Shi <[email protected]>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <[email protected]>

								Honza

> ---
>  fs/buffer.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 50a63d964815..ac978d9090c2 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -618,7 +618,7 @@ int mmb_sync(struct mapping_metadata_bhs *mmb)
>  		}
>  		spin_unlock(&mmb->lock);
>  		wait_on_buffer(bh);
> -		if (!buffer_uptodate(bh))
> +		if (buffer_write_io_error(bh))
>  			err = -EIO;
>  		brelse(bh);
>  		spin_lock(&mmb->lock);
> @@ -2743,7 +2743,7 @@ int __sync_dirty_buffer(struct buffer_head *bh, blk_opf_t op_flags)
>  
>  		bh_submit(bh, REQ_OP_WRITE | op_flags, bh_end_write);
>  		wait_on_buffer(bh);
> -		if (!buffer_uptodate(bh))
> +		if (buffer_write_io_error(bh))
>  			return -EIO;
>  	} else {
>  		unlock_buffer(bh);
> -- 
> 2.43.0
> 
-- 
Jan Kara <[email protected]>
SUSE Labs, CR