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Subject: Re: [PATCH v2] fs: Handle I_DONTCACHE in iput_final() instead of
 generic_drop_inode()
From:   "Li, Hao" <lihao2018.fnst@cn.fujitsu.com>
To:     <viro@zeniv.linux.org.uk>
CC:     <linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
        <david@fromorbit.com>, <linux-xfs@vger.kernel.org>,
        <y-goto@fujitsu.com>, "Ira Weiny" <ira.weiny@intel.com>
References: <20200904075939.176366-1-lihao2018.fnst@cn.fujitsu.com>
 <20200908230331.GF1930795@iweiny-DESK2.sc.intel.com>
 <f1d1a56f-caec-3c68-6c70-1b6f995cab95@cn.fujitsu.com>
Message-ID: <5e3a45e3-c4a7-aadf-9fbe-9a51929bb58d@cn.fujitsu.com>
Date:   Thu, 5 Nov 2020 18:55:11 +0800
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Ping :)


On 2020/10/23 15:49, Li, Hao wrote:
> Hello,
>
> Ping.
>
> This patch need to be merged... Thanks.
>
> On 2020/9/9 7:03, Ira Weiny wrote:
>> On Fri, Sep 04, 2020 at 03:59:39PM +0800, Hao Li wrote:
>>> If generic_drop_inode() returns true, it means iput_final() can evict
>>> this inode regardless of whether it is dirty or not. If we check
>>> I_DONTCACHE in generic_drop_inode(), any inode with this bit set will be
>>> evicted unconditionally. This is not the desired behavior because
>>> I_DONTCACHE only means the inode shouldn't be cached on the LRU list.
>>> As for whether we need to evict this inode, this is what
>>> generic_drop_inode() should do. This patch corrects the usage of
>>> I_DONTCACHE.
>>>
>>> This patch was proposed in [1].
>>>
>>> [1]: https://lore.kernel.org/linux-fsdevel/20200831003407.GE12096@dread.disaster.area/
>>>
>>> Fixes: dae2f8ed7992 ("fs: Lift XFS_IDONTCACHE to the VFS layer")
>>> Signed-off-by: Hao Li <lihao2018.fnst@cn.fujitsu.com>
>> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
>>
>>> ---
>>> Changes in v2:
>>>  - Adjust code format
>>>  - Add Fixes tag in commit message
>>>
>>>  fs/inode.c         | 4 +++-
>>>  include/linux/fs.h | 3 +--
>>>  2 files changed, 4 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/inode.c b/fs/inode.c
>>> index 72c4c347afb7..19ad823f781c 100644
>>> --- a/fs/inode.c
>>> +++ b/fs/inode.c
>>> @@ -1625,7 +1625,9 @@ static void iput_final(struct inode *inode)
>>>  	else
>>>  		drop = generic_drop_inode(inode);
>>>  
>>> -	if (!drop && (sb->s_flags & SB_ACTIVE)) {
>>> +	if (!drop &&
>>> +	    !(inode->i_state & I_DONTCACHE) &&
>>> +	    (sb->s_flags & SB_ACTIVE)) {
>>>  		inode_add_lru(inode);
>>>  		spin_unlock(&inode->i_lock);
>>>  		return;
>>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>>> index e019ea2f1347..93caee80ce47 100644
>>> --- a/include/linux/fs.h
>>> +++ b/include/linux/fs.h
>>> @@ -2922,8 +2922,7 @@ extern int inode_needs_sync(struct inode *inode);
>>>  extern int generic_delete_inode(struct inode *inode);
>>>  static inline int generic_drop_inode(struct inode *inode)
>>>  {
>>> -	return !inode->i_nlink || inode_unhashed(inode) ||
>>> -		(inode->i_state & I_DONTCACHE);
>>> +	return !inode->i_nlink || inode_unhashed(inode);
>>>  }
>>>  extern void d_mark_dontcache(struct inode *inode);
>>>  
>>> -- 
>>> 2.28.0
>>>
>>>
>>>
>