linux-ext4 - Re: [PATCH v2 11/14] ufs: replace ll_rw

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Date:   Thu, 1 Sep 2022 17:59:11 +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 11/14] ufs: replace ll_rw_block()

On Thu 01-09-22 21:35:02, 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() in ufs.
> 
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>

Looks good to me. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ufs/balloc.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/ufs/balloc.c b/fs/ufs/balloc.c
> index bd810d8239f2..2436e3f82147 100644
> --- a/fs/ufs/balloc.c
> +++ b/fs/ufs/balloc.c
> @@ -295,14 +295,10 @@ static void ufs_change_blocknr(struct inode *inode, sector_t beg,
>  
>  			if (!buffer_mapped(bh))
>  					map_bh(bh, inode->i_sb, oldb + pos);
> -			if (!buffer_uptodate(bh)) {
> -				ll_rw_block(REQ_OP_READ, 1, &bh);
> -				wait_on_buffer(bh);
> -				if (!buffer_uptodate(bh)) {
> -					ufs_error(inode->i_sb, __func__,
> -						  "read of block failed\n");
> -					break;
> -				}
> +			if (bh_read(bh, 0) < 0) {
> +				ufs_error(inode->i_sb, __func__,
> +					  "read of block failed\n");
> +				break;
>  			}
>  
>  			UFSD(" change from %llu to %llu, pos %u\n",
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR