linux-ext4 - Re: [PATCH v2 10/14] udf: replace ll_rw

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Date:   Thu, 1 Sep 2022 17:58:38 +0200
From:   Jan Kara <jack@...e.cz>
To:     Zhang Yi <yi.zhang@...wei.com>
Cc:     linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, cluster-devel@...hat.com,
        ntfs3@...ts.linux.dev, ocfs2-devel@....oracle.com,
        reiserfs-devel@...r.kernel.org, jack@...e.cz, tytso@....edu,
        akpm@...ux-foundation.org, axboe@...nel.dk,
        viro@...iv.linux.org.uk, rpeterso@...hat.com, agruenba@...hat.com,
        almaz.alexandrovich@...agon-software.com, mark@...heh.com,
        dushistov@...l.ru, hch@...radead.org, chengzhihao1@...wei.com,
        yukuai3@...wei.com
Subject: Re: [PATCH v2 10/14] udf: replace ll_rw_block()

On Thu 01-09-22 21:35:01, Zhang Yi wrote:
> ll_rw_block() is not safe for the sync read path because it cannot
> guarantee that submitting read IO if the buffer has been locked. We
> could get false positive EIO after wait_on_buffer() if the buffer has
> been locked by others. So stop using ll_rw_block(). We also switch to
> new bh_readahead_batch() helper for the buffer array readahead path.
> 
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>

Looks good to me.

								Honza

> ---
>  fs/udf/dir.c       | 2 +-
>  fs/udf/directory.c | 2 +-
>  fs/udf/inode.c     | 8 +-------
>  3 files changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/udf/dir.c b/fs/udf/dir.c
> index cad3772f9dbe..be640f4b2f2c 100644
> --- a/fs/udf/dir.c
> +++ b/fs/udf/dir.c
> @@ -130,7 +130,7 @@ static int udf_readdir(struct file *file, struct dir_context *ctx)
>  					brelse(tmp);
>  			}
>  			if (num) {
> -				ll_rw_block(REQ_OP_READ | REQ_RAHEAD, num, bha);
> +				bh_readahead_batch(num, bha, REQ_RAHEAD);
>  				for (i = 0; i < num; i++)
>  					brelse(bha[i]);
>  			}
> diff --git a/fs/udf/directory.c b/fs/udf/directory.c
> index a2adf6293093..16bcf2c6b8b3 100644
> --- a/fs/udf/directory.c
> +++ b/fs/udf/directory.c
> @@ -89,7 +89,7 @@ struct fileIdentDesc *udf_fileident_read(struct inode *dir, loff_t *nf_pos,
>  					brelse(tmp);
>  			}
>  			if (num) {
> -				ll_rw_block(REQ_OP_READ | REQ_RAHEAD, num, bha);
> +				bh_readahead_batch(num, bha, REQ_RAHEAD);
>  				for (i = 0; i < num; i++)
>  					brelse(bha[i]);
>  			}
> diff --git a/fs/udf/inode.c b/fs/udf/inode.c
> index 8d06daed549f..dce6ae9ae306 100644
> --- a/fs/udf/inode.c
> +++ b/fs/udf/inode.c
> @@ -1211,13 +1211,7 @@ struct buffer_head *udf_bread(struct inode *inode, udf_pblk_t block,
>  	if (!bh)
>  		return NULL;
>  
> -	if (buffer_uptodate(bh))
> -		return bh;
> -
> -	ll_rw_block(REQ_OP_READ, 1, &bh);
> -
> -	wait_on_buffer(bh);
> -	if (buffer_uptodate(bh))
> +	if (bh_read(bh, 0) >= 0)
>  		return bh;
>  
>  	brelse(bh);
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR