linux-kernel - Re: [PATCH 3/4] f2fs: compress: fix error path in prepare_compress

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Message-ID: <20200106190809.GE50058@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Mon, 6 Jan 2020 11:08:09 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [PATCH 3/4] f2fs: compress: fix error path in
 prepare_compress_overwrite()

On 01/06, Chao Yu wrote:
> - fix to release cluster pages in retry flow
> - fix to call f2fs_put_dnode() & __do_map_lock() in error path
> 
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
>  fs/f2fs/compress.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index fc4510729654..3390351d2e39 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -626,20 +626,26 @@ static int prepare_compress_overwrite(struct compress_ctx *cc,
>  	}
>  
>  	for (i = 0; i < cc->cluster_size; i++) {
> +		f2fs_bug_on(sbi, cc->rpages[i]);
> +
>  		page = find_lock_page(mapping, start_idx + i);
>  		f2fs_bug_on(sbi, !page);
>  
>  		f2fs_wait_on_page_writeback(page, DATA, true, true);
>  
> -		cc->rpages[i] = page;
> +		f2fs_compress_ctx_add_page(cc, page);
>  		f2fs_put_page(page, 0);
>  
>  		if (!PageUptodate(page)) {
> -			for (idx = 0; idx < cc->cluster_size; idx++) {
> -				f2fs_put_page(cc->rpages[idx],
> -						(idx <= i) ? 1 : 0);
> +			for (idx = 0; idx <= i; idx++) {
> +				unlock_page(cc->rpages[idx]);
>  				cc->rpages[idx] = NULL;
>  			}
> +			for (idx = 0; idx < cc->cluster_size; idx++) {
> +				page = find_lock_page(mapping, start_idx + idx);

Why do we need to lock the pages again?

> +				f2fs_put_page(page, 1);
> +				f2fs_put_page(page, 0);
> +			}
>  			kvfree(cc->rpages);
>  			cc->nr_rpages = 0;
>  			goto retry;
> @@ -654,16 +660,20 @@ static int prepare_compress_overwrite(struct compress_ctx *cc,
>  		for (i = cc->cluster_size - 1; i > 0; i--) {
>  			ret = f2fs_get_block(&dn, start_idx + i);
>  			if (ret) {
> -				/* TODO: release preallocate blocks */
>  				i = cc->cluster_size;
> -				goto unlock_pages;
> +				break;
>  			}
>  
>  			if (dn.data_blkaddr != NEW_ADDR)
>  				break;
>  		}
>  
> +		f2fs_put_dnode(&dn);

We don't neeed this, since f2fs_reserve_block() put the dnode.

> +
>  		__do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, false);
> +
> +		if (ret)
> +			goto unlock_pages;
>  	}
>  
>  	*fsdata = cc->rpages;
> -- 
> 2.18.0.rc1