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Date:   Wed, 31 Aug 2022 13:04:47 +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 09/14] reiserfs: replace ll_rw_block()

On Wed 31-08-22 15:21:06, Zhang Yi wrote:
> ll_rw_block() is not safe for the sync read/write path because it cannot
> guarantee that submitting read/write IO if the buffer has been locked.
> We could get false positive EIO after wait_on_buffer() in read path if
> the buffer has been locked by others. So stop using ll_rw_block() in
> reiserfs. 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. Feel free to add:

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

								Honza

> ---
>  fs/reiserfs/journal.c | 11 ++++++-----
>  fs/reiserfs/stree.c   |  4 ++--
>  fs/reiserfs/super.c   |  4 +---
>  3 files changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
> index 94addfcefede..699b1b8d5b73 100644
> --- a/fs/reiserfs/journal.c
> +++ b/fs/reiserfs/journal.c
> @@ -868,7 +868,7 @@ static int write_ordered_buffers(spinlock_t * lock,
>  		 */
>  		if (buffer_dirty(bh) && unlikely(bh->b_page->mapping == NULL)) {
>  			spin_unlock(lock);
> -			ll_rw_block(REQ_OP_WRITE, 1, &bh);
> +			write_dirty_buffer(bh, 0);
>  			spin_lock(lock);
>  		}
>  		put_bh(bh);
> @@ -1054,7 +1054,7 @@ static int flush_commit_list(struct super_block *s,
>  		if (tbh) {
>  			if (buffer_dirty(tbh)) {
>  		            depth = reiserfs_write_unlock_nested(s);
> -			    ll_rw_block(REQ_OP_WRITE, 1, &tbh);
> +			    write_dirty_buffer(tbh, 0);
>  			    reiserfs_write_lock_nested(s, depth);
>  			}
>  			put_bh(tbh) ;
> @@ -2240,7 +2240,7 @@ static int journal_read_transaction(struct super_block *sb,
>  		}
>  	}
>  	/* read in the log blocks, memcpy to the corresponding real block */
> -	ll_rw_block(REQ_OP_READ, get_desc_trans_len(desc), log_blocks);
> +	bh_read_batch(log_blocks, get_desc_trans_len(desc));
>  	for (i = 0; i < get_desc_trans_len(desc); i++) {
>  
>  		wait_on_buffer(log_blocks[i]);
> @@ -2342,10 +2342,11 @@ static struct buffer_head *reiserfs_breada(struct block_device *dev,
>  		} else
>  			bhlist[j++] = bh;
>  	}
> -	ll_rw_block(REQ_OP_READ, j, bhlist);
> +	bh = bhlist[0];
> +	bh_read_nowait(bh, 0);
> +	bh_readahead_batch(&bhlist[1], j - 1, 0);
>  	for (i = 1; i < j; i++)
>  		brelse(bhlist[i]);
> -	bh = bhlist[0];
>  	wait_on_buffer(bh);
>  	if (buffer_uptodate(bh))
>  		return bh;
> diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c
> index 9a293609a022..84c12a1947b2 100644
> --- a/fs/reiserfs/stree.c
> +++ b/fs/reiserfs/stree.c
> @@ -579,7 +579,7 @@ static int search_by_key_reada(struct super_block *s,
>  		if (!buffer_uptodate(bh[j])) {
>  			if (depth == -1)
>  				depth = reiserfs_write_unlock_nested(s);
> -			ll_rw_block(REQ_OP_READ | REQ_RAHEAD, 1, bh + j);
> +			bh_readahead(bh[j], REQ_RAHEAD);
>  		}
>  		brelse(bh[j]);
>  	}
> @@ -685,7 +685,7 @@ int search_by_key(struct super_block *sb, const struct cpu_key *key,
>  			if (!buffer_uptodate(bh) && depth == -1)
>  				depth = reiserfs_write_unlock_nested(sb);
>  
> -			ll_rw_block(REQ_OP_READ, 1, &bh);
> +			bh_read_nowait(bh, 0);
>  			wait_on_buffer(bh);
>  
>  			if (depth != -1)
> diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
> index c88cd2ce0665..8b1db82b6949 100644
> --- a/fs/reiserfs/super.c
> +++ b/fs/reiserfs/super.c
> @@ -1702,9 +1702,7 @@ static int read_super_block(struct super_block *s, int offset)
>  /* after journal replay, reread all bitmap and super blocks */
>  static int reread_meta_blocks(struct super_block *s)
>  {
> -	ll_rw_block(REQ_OP_READ, 1, &SB_BUFFER_WITH_SB(s));
> -	wait_on_buffer(SB_BUFFER_WITH_SB(s));
> -	if (!buffer_uptodate(SB_BUFFER_WITH_SB(s))) {
> +	if (bh_read(SB_BUFFER_WITH_SB(s), 0)) {
>  		reiserfs_warning(s, "reiserfs-2504", "error reading the super");
>  		return 1;
>  	}
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR

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