[Ocfs2-devel] [PATCH] ocfs2: using i_size_read() to access i_size

From: Junxiao Bi <junxiao.bi@oracle.com>
To: ocfs2-devel@oss.oracle.com
Subject: [Ocfs2-devel] [PATCH] ocfs2: using i_size_read() to access i_size
Date: Fri, 19 Jul 2013 16:12:34 +0800	[thread overview]
Message-ID: <51E8F4F2.7010205@oracle.com> (raw)
In-Reply-To: <51E8F2E0.6000207@oracle.com>

Hi Jeff,

On 07/19/2013 04:03 PM, Jeff Liu wrote:
> Hi Junxiao,
>
> On 07/19/2013 03:38 PM, Junxiao Bi wrote:
>
>> Hi Jeff,
>>
>> On 07/17/2013 07:13 AM, Jeff Liu wrote:
>>>>> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
>>>>>>> index 3ce6a8b..7158710 100644
>>>>>>> --- a/fs/ocfs2/file.c
>>>>>>> +++ b/fs/ocfs2/file.c
>>>>>>> @@ -2650,7 +2650,7 @@ static loff_t ocfs2_file_llseek(struct file *file, loff_t offset, int whence)
>>> We have the inode mutex around ocfs2_file_llseek(), and that is too extensive
>>> to block the concurrent access for particular seek operations.  At least,
>>> we can get rid of this lock for SEEK_SET/SEEK_CUR. i.e,  In either case,
>>> we can fall through generic_file_llseek() directly without the mutex lock.
>> Think about this again, I think we can't remove the mutex, as it is used
>> to protect other inode member beside i_size, like
>> inode->i_sb->s_maxbytes which is accessed in all SEEK request and also
>> more in ocfs2_inode_lock().
> Thanks for digging into this.  s_maxbytes is a numeric constant which is
> calculated out at OCFS2 mount with filling up the super blocks, IOWs, it
> does not need any lock protection IMO.
>
> Besides that, could you please pointed me out anything am missed?
Can inode->i_sb be set to NULL during this?

Thanks,
Junxiao.
>
> Thanks,
> -Jeff
>
>> Thanks,
>> Junxiao.
>>>>>>>  	case SEEK_SET:
>>>>>>>  		break;
>>>>>>>  	case SEEK_END:
>>>>>>> -		offset += inode->i_size;
>>>>>>> +		offset += i_size_read(inode);
>