[Ocfs2-devel] [PATCH v2] ocfs2: roll back the reference count modification of the parent directory if an error occurs

[Joseph Qi]

On 2020/3/17 14:24, piaojun wrote:
> 
> 
> On 2020/3/17 10:26, wangjian wrote:
>> Under some conditions, the directory cannot be deleted.
>> The specific scenarios are as follows: (for example,
>> /mnt/ocfs2 is the mount point)
>>
>> 1. Create the /mnt/ocfs2/p_dir directory. At this time,
>> the i_nlink corresponding to the inode of
>> the /mnt/ocfs2/p_dir directory is equal to 2.
>>
>> 2. During the process of creating the
>> /mnt/ocfs2/p_dir/s_dir directory, if the call to the inc_nlink
>> function in ocfs2_mknod succeeds, the functions such as
>> ocfs2_init_acl, ocfs2_init_security_set, and ocfs2_dentry_attach_lock fail.
>> At this time, the i_nlink corresponding to the inode of the
>> /mnt/ocfs2/p_dir directory is equal to 3, but /mnt/ocfs2/p_dir/s_dir
>> is not added to the /mnt/ocfs2/p_dir directory entry.
>>
>> 3. Delete the /mnt/ocfs2/p_dir directory (rm -rf /mnt/ocfs2/p_dir).
>> At this time, it is found that the i_nlink corresponding to
>> the inode corresponding to the /mnt/ocfs2/p_dir directory is equal to 3.
>> Therefore, the /mnt/ocfs2/p_dir directory cannot be deleted.
>>
>> Signed-off-by: Jian wang <wangjian161 at huawei.com>
>> ---
>>  ocfs2/namei.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/ocfs2/namei.c b/ocfs2/namei.c
>> index 8ea51cf..f34ce0b 100644
>> --- a/ocfs2/namei.c
>> +++ b/ocfs2/namei.c
>> @@ -247,6 +247,7 @@ static int ocfs2_mknod(struct inode *dir,
>>  	sigset_t oldset;
>>  	int did_block_signals = 0;
>>  	struct ocfs2_dentry_lock *dl = NULL;
>> +	int link_inc = 0;
>>  
>>  	trace_ocfs2_mknod(dir, dentry, dentry->d_name.len, dentry->d_name.name,
>>  			  (unsigned long long)OCFS2_I(dir)->ip_blkno,
>> @@ -399,6 +400,7 @@ static int ocfs2_mknod(struct inode *dir,
>>  		ocfs2_add_links_count(dirfe, 1);
>>  		ocfs2_journal_dirty(handle, parent_fe_bh);
>>  		inc_nlink(dir);
>> +		link_inc = 1;
>>  	}
>>  
>>  	status = ocfs2_init_acl(handle, inode, dir, new_fe_bh, parent_fe_bh,
>> @@ -444,6 +446,12 @@ static int ocfs2_mknod(struct inode *dir,
>>  	d_instantiate(dentry, inode);
>>  	status = 0;
>>  leave:
>> +	if (status < 0 && S_ISDIR(mode) && link_inc != 0) {
>> +		ocfs2_add_links_count(dirfe, -1);
>> +		ocfs2_journal_dirty(handle, parent_fe_bh);
> There is no need to re-dirty 'parent_fe_bh'. And I suggest adding a new
> roll_back tag to handle this, just like ocfs2_orphan_add() does.
> 
Good idea, that will be more clearly and we don't need the flag link_inc any more.

Thanks,
Joseph