linux-ext4 - Re: [PATCH v3 2/2] ext4: restore len when ext4_ext_insert

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Date:   Tue, 7 Feb 2023 15:23:56 +0100
From:   Jan Kara <jack@...e.cz>
To:     zhanchengbin <zhanchengbin1@...wei.com>
Cc:     tytso@....edu, jack@...e.com, linux-ext4@...r.kernel.org,
        yi.zhang@...wei.com, linfeilong@...wei.com,
        liuzhiqiang26@...wei.com
Subject: Re: [PATCH v3 2/2] ext4: restore len when ext4_ext_insert_extent
 failed

On Tue 07-02-23 15:09:31, zhanchengbin wrote:
> Inside the ext4_ext_insert_extent function, every error returned will
> not destroy the consistency of the tree. Even if it fails after changing
> half of the tree, can also ensure that the tree is self-consistent, like
> function ext4_ext_create_new_leaf.

Hum, but e.g. if ext4_ext_correct_indexes() fails, we *will* end up with
corrupted extent tree pretty much without a chance for recovery, won't we?

								Honza

> After ext4_ext_insert_extent fails, update extent status tree depends on
> the incoming split_flag. So restore the len of extent to be split when
> ext4_ext_insert_extent return failed in ext4_split_extent_at.
> 
> Signed-off-by: zhanchengbin <zhanchengbin1@...wei.com>
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
> ---
>  fs/ext4/extents.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 3559ea6b0781..b926fef73de4 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -935,6 +935,7 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block,
>  
>  		bh = read_extent_tree_block(inode, path[ppos].p_idx, --i, flags);
>  		if (IS_ERR(bh)) {
> +			EXT4_ERROR_INODE(inode, "IO error reading extent block");
>  			ret = PTR_ERR(bh);
>  			goto err;
>  		}
> @@ -3251,7 +3252,7 @@ static int ext4_split_extent_at(handle_t *handle,
>  		ext4_ext_mark_unwritten(ex2);
>  
>  	err = ext4_ext_insert_extent(handle, inode, ppath, &newex, flags);
> -	if (err != -ENOSPC && err != -EDQUOT && err != -ENOMEM)
> +	if (!err)
>  		goto out;
>  
>  	if (EXT4_EXT_MAY_ZEROOUT & split_flag) {
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR