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Date:   Mon, 29 Jun 2020 13:22:13 -0600
From:   Andreas Dilger <adilger@...ger.ca>
To:     Yi Zhuang <zhuangyi1@...wei.com>
Cc:     "Theodore Y. Ts'o" <tytso@....edu>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH v2] ext4: lost matching-pair of trace in ext4_unlink


> On Jun 29, 2020, at 6:26 AM, Yi Zhuang <zhuangyi1@...wei.com> wrote:
> 
> If dquot_initialize() return non-zero and trace of ext4_unlink_enter/exit
> enabled then the matching-pair of trace_exit will lost in log.
> 
> v2:
> Change the new label to be "out_trace:", which makes it more clear that
> it is undoing the "trace" part of the code. At the same time, fix other
> similar problems in this function:
> 
> 	bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
> 	if (IS_ERR(bh))
> 		return PTR_ERR(bh);
> 	if (!bh)
> 		goto end_unlink;
> 
> According to Andreas' suggestion, split up the "end_unlink:" label becomes
> two separate labels, and then remove the "if (handle)" check, and then
> use out_bh: before the handle is started.
> 
> Signed-off-by: Yi Zhuang <zhuangyi1@...wei.com>

Reviewed-by: Andreas Dilger <adilger@...ger.ca>

> ---
> fs/ext4/namei.c | 38 +++++++++++++++++++++-----------------
> 1 file changed, 21 insertions(+), 17 deletions(-)
> 
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index 56738b538ddf..941f66f417f0 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -3193,30 +3193,33 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
> 	 * in separate transaction */
> 	retval = dquot_initialize(dir);
> 	if (retval)
> -		return retval;
> +		goto out_trace;
> 	retval = dquot_initialize(d_inode(dentry));
> 	if (retval)
> -		return retval;
> +		goto out_trace;
> 
> -	retval = -ENOENT;
> 	bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
> -	if (IS_ERR(bh))
> -		return PTR_ERR(bh);
> -	if (!bh)
> -		goto end_unlink;
> +	if (IS_ERR(bh)) {
> +		retval = PTR_ERR(bh);
> +		goto out_trace;
> +	}
> +	if (!bh) {
> +		retval = -ENOENT;
> +		goto out_trace;
> +	}
> 
> 	inode = d_inode(dentry);
> 
> -	retval = -EFSCORRUPTED;
> -	if (le32_to_cpu(de->inode) != inode->i_ino)
> -		goto end_unlink;
> +	if (le32_to_cpu(de->inode) != inode->i_ino) {
> +		retval = -EFSCORRUPTED;
> +		goto out_bh;
> +	}
> 
> 	handle = ext4_journal_start(dir, EXT4_HT_DIR,
> 				    EXT4_DATA_TRANS_BLOCKS(dir->i_sb));
> 	if (IS_ERR(handle)) {
> 		retval = PTR_ERR(handle);
> -		handle = NULL;
> -		goto end_unlink;
> +		goto out_bh;
> 	}
> 
> 	if (IS_DIRSYNC(dir))
> @@ -3224,12 +3227,12 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
> 
> 	retval = ext4_delete_entry(handle, dir, de, bh);
> 	if (retval)
> -		goto end_unlink;
> +		goto out_handle;
> 	dir->i_ctime = dir->i_mtime = current_time(dir);
> 	ext4_update_dx_flag(dir);
> 	retval = ext4_mark_inode_dirty(handle, dir);
> 	if (retval)
> -		goto end_unlink;
> +		goto out_handle;
> 	if (inode->i_nlink == 0)
> 		ext4_warning_inode(inode, "Deleting file '%.*s' with no links",
> 				   dentry->d_name.len, dentry->d_name.name);
> @@ -3251,10 +3254,11 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
> 		d_invalidate(dentry);
> #endif
> 
> -end_unlink:
> +out_handle:
> +	ext4_journal_stop(handle);
> +out_bh:
> 	brelse(bh);
> -	if (handle)
> -		ext4_journal_stop(handle);
> +out_trace:
> 	trace_ext4_unlink_exit(dentry, retval);
> 	return retval;
> }
> --
> 2.26.0.106.g9fadedd
> 


Cheers, Andreas






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