Re: [External] : [PATCH] ocfs2: retire ocfs2_drop_inode() and I_WILL_FREE usage

[Joseph Qi <joseph.qi@linux.alibaba.com>]

On 2025/9/5 00:15, Mark Tinguely wrote:
> On 9/4/25 10:42 AM, Mateusz Guzik wrote:
>> This postpones the writeout to ocfs2_evict_inode(), which I'm told is
>> fine (tm).
>>
>> The intent is to retire the I_WILL_FREE flag.
>>
>> Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
>> ---
>>
>> ACHTUNG: only compile-time tested. Need an ocfs2 person to ack it.
>>
>> btw grep shows comments referencing ocfs2_drop_inode() which are already
>> stale on the stock kernel, I opted to not touch them.
>>
>> This ties into an effort to remove the I_WILL_FREE flag, unblocking
>> other work. If accepted would be probably best taken through vfs
>> branches with said work, see https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git/log/?h=vfs-6.18.inode.refcount.preliminaries__;!!ACWV5N9M2RV99hQ!OLwk8DVo7uvC-Pd6XVTiUCgP6MUDMKBMEyuV27h_yPGXOjaq078-kMdC9ILFoYQh-4WX93yb0nMfBDFFY_0$
>>
>>   fs/ocfs2/inode.c       | 23 ++---------------------
>>   fs/ocfs2/inode.h       |  1 -
>>   fs/ocfs2/ocfs2_trace.h |  2 --
>>   fs/ocfs2/super.c       |  2 +-
>>   4 files changed, 3 insertions(+), 25 deletions(-)
>>
>> diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
>> index 6c4f78f473fb..5f4a2cbc505d 100644
>> --- a/fs/ocfs2/inode.c
>> +++ b/fs/ocfs2/inode.c
>> @@ -1290,6 +1290,8 @@ static void ocfs2_clear_inode(struct inode *inode)
>>     void ocfs2_evict_inode(struct inode *inode)
>>   {
>> +    write_inode_now(inode, 1);
>> +
>>       if (!inode->i_nlink ||
>>           (OCFS2_I(inode)->ip_flags & OCFS2_INODE_MAYBE_ORPHANED)) {
>>           ocfs2_delete_inode(inode);
>> @@ -1299,27 +1301,6 @@ void ocfs2_evict_inode(struct inode *inode)
>>       ocfs2_clear_inode(inode);
>>   }
>>   -/* Called under inode_lock, with no more references on the
>> - * struct inode, so it's safe here to check the flags field
>> - * and to manipulate i_nlink without any other locks. */
>> -int ocfs2_drop_inode(struct inode *inode)
>> -{
>> -    struct ocfs2_inode_info *oi = OCFS2_I(inode);
>> -
>> -    trace_ocfs2_drop_inode((unsigned long long)oi->ip_blkno,
>> -                inode->i_nlink, oi->ip_flags);
>> -
>> -    assert_spin_locked(&inode->i_lock);
>> -    inode->i_state |= I_WILL_FREE;
>> -    spin_unlock(&inode->i_lock);
>> -    write_inode_now(inode, 1);
>> -    spin_lock(&inode->i_lock);
>> -    WARN_ON(inode->i_state & I_NEW);
>> -    inode->i_state &= ~I_WILL_FREE;
>> -
>> -    return 1;
>> -}
>> -
>>   /*
>>    * This is called from our getattr.
>>    */
>> diff --git a/fs/ocfs2/inode.h b/fs/ocfs2/inode.h
>> index accf03d4765e..07bd838e7843 100644
>> --- a/fs/ocfs2/inode.h
>> +++ b/fs/ocfs2/inode.h
>> @@ -116,7 +116,6 @@ static inline struct ocfs2_caching_info *INODE_CACHE(struct inode *inode)
>>   }
>>     void ocfs2_evict_inode(struct inode *inode);
>> -int ocfs2_drop_inode(struct inode *inode);
>>     /* Flags for ocfs2_iget() */
>>   #define OCFS2_FI_FLAG_SYSFILE        0x1
>> diff --git a/fs/ocfs2/ocfs2_trace.h b/fs/ocfs2/ocfs2_trace.h
>> index 54ed1495de9a..4b32fb5658ad 100644
>> --- a/fs/ocfs2/ocfs2_trace.h
>> +++ b/fs/ocfs2/ocfs2_trace.h
>> @@ -1569,8 +1569,6 @@ DEFINE_OCFS2_ULL_ULL_UINT_EVENT(ocfs2_delete_inode);
>>     DEFINE_OCFS2_ULL_UINT_EVENT(ocfs2_clear_inode);
>>   -DEFINE_OCFS2_ULL_UINT_UINT_EVENT(ocfs2_drop_inode);
>> -
>>   TRACE_EVENT(ocfs2_inode_revalidate,
>>       TP_PROTO(void *inode, unsigned long long ino,
>>            unsigned int flags),
>> diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
>> index 53daa4482406..e4b0d25f4869 100644
>> --- a/fs/ocfs2/super.c
>> +++ b/fs/ocfs2/super.c
>> @@ -129,7 +129,7 @@ static const struct super_operations ocfs2_sops = {
>>       .statfs        = ocfs2_statfs,
>>       .alloc_inode    = ocfs2_alloc_inode,
>>       .free_inode    = ocfs2_free_inode,
>> -    .drop_inode    = ocfs2_drop_inode,
>> +    .drop_inode    = generic_delete_inode,
>>       .evict_inode    = ocfs2_evict_inode,
>>       .sync_fs    = ocfs2_sync_fs,
>>       .put_super    = ocfs2_put_super,
> 
> 
> I agree, fileystems should not use I_FREEING/I_WILL_FREE.
> Doing the sync write_inode_now() should be fine in ocfs_evict_inode().
> 
> Question is ocfs_drop_inode. In commit 513e2dae9422:
>  ocfs2: flush inode data to disk and free inode when i_count becomes zero
> the return of 1 drops immediate to fix a memory caching issue.
> Shouldn't .drop_inode() still return 1?
> 
I think commit 513e2dae9422 only expected the write_inode_now() is
determinately called in iput_final(), no matter drop_inode() return 0 or
1.

Thanks,
Joseph