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Message-ID: <8ddcaa59-0cf0-4b7c-a121-924105f7f5a6@linux.alibaba.com>
Date: Mon, 8 Sep 2025 09:51:36 +0800
From: Joseph Qi <joseph.qi@...ux.alibaba.com>
To: Mateusz Guzik <mjguzik@...il.com>,
Mark Tinguely <mark.tinguely@...cle.com>
Cc: ocfs2-devel@...ts.linux.dev, viro@...iv.linux.org.uk, jack@...e.cz,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
josef@...icpanda.com, jlbec@...lplan.org, mark@...heh.com,
brauner@...nel.org, willy@...radead.org, david@...morbit.com
Subject: Re: [External] : [PATCH] ocfs2: retire ocfs2_drop_inode() and
I_WILL_FREE usage
On 2025/9/5 00:22, Mateusz Guzik wrote:
> On Thu, Sep 4, 2025 at 6:15 PM Mark Tinguely <mark.tinguely@...cle.com> 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@...il.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?
>
> generic_delete_inode is a stub doing just that.
>
In case of "drop = 0", it may return directly without calling evict().
This seems break the expectation of commit 513e2dae9422.
Thanks,
Joseph
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