linux-kernel - Re: [PATCH v4 2/2] ceph: add ceph specific member support for file

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Date:   Wed, 14 Dec 2022 10:03:49 +0800
From:   Xiubo Li <xiubli@...hat.com>
To:     Ilya Dryomov <idryomov@...il.com>
Cc:     jlayton@...nel.org, ceph-devel@...r.kernel.org,
        mchangir@...hat.com, lhenriques@...e.de, viro@...iv.linux.org.uk,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v4 2/2] ceph: add ceph specific member support for
 file_lock


On 14/12/2022 02:05, Ilya Dryomov wrote:
> On Tue, Dec 13, 2022 at 1:11 PM <xiubli@...hat.com> wrote:
>> From: Xiubo Li <xiubli@...hat.com>
>>
>> When ceph releasing the file_lock it will try to get the inode pointer
>> from the fl->fl_file, which the memory could already be released by
>> another thread in filp_close(). Because in VFS layer the fl->fl_file
>> doesn't increase the file's reference counter.
>>
>> Will switch to use ceph dedicate lock info to track the inode.
>>
>> And in ceph_fl_release_lock() we should skip all the operations if
>> the fl->fl_u.ceph_fl.fl_inode is not set, which should come from
>> the request file_lock. And we will set fl->fl_u.ceph_fl.fl_inode when
>> inserting it to the inode lock list, which is when copying the lock.
>>
>> Cc: stable@...r.kernel.org
>> Cc: Jeff Layton <jlayton@...nel.org>
>> URL: https://tracker.ceph.com/issues/57986
>> Signed-off-by: Xiubo Li <xiubli@...hat.com>
>> ---
>>   fs/ceph/locks.c    | 20 ++++++++++++++++++--
>>   include/linux/fs.h |  3 +++
>>   2 files changed, 21 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
>> index b191426bf880..cf78608a3f9a 100644
>> --- a/fs/ceph/locks.c
>> +++ b/fs/ceph/locks.c
>> @@ -34,18 +34,34 @@ static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
>>   {
>>          struct inode *inode = file_inode(dst->fl_file);
>>          atomic_inc(&ceph_inode(inode)->i_filelock_ref);
>> +       dst->fl_u.ceph.fl_inode = igrab(inode);
>>   }
>>
>> +/*
>> + * Do not use the 'fl->fl_file' in release function, which
>> + * is possibly already released by another thread.
>> + */
>>   static void ceph_fl_release_lock(struct file_lock *fl)
>>   {
>> -       struct inode *inode = file_inode(fl->fl_file);
>> -       struct ceph_inode_info *ci = ceph_inode(inode);
>> +       struct inode *inode = fl->fl_u.ceph.fl_inode;
>> +       struct ceph_inode_info *ci;
>> +
>> +       /*
>> +        * If inode is NULL it should be a request file_lock,
>> +        * nothing we can do.
>> +        */
>> +       if (!inode)
>> +               return;
>> +
>> +       ci = ceph_inode(inode);
>>          if (atomic_dec_and_test(&ci->i_filelock_ref)) {
>>                  /* clear error when all locks are released */
>>                  spin_lock(&ci->i_ceph_lock);
>>                  ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK;
>>                  spin_unlock(&ci->i_ceph_lock);
>>          }
>> +       fl->fl_u.ceph.fl_inode = NULL;
>> +       iput(inode);
>>   }
>>
>>   static const struct file_lock_operations ceph_fl_lock_ops = {
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index 7b52fdfb6da0..6106374f5257 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -1119,6 +1119,9 @@ struct file_lock {
>>                          int state;              /* state of grant or error if -ve */
>>                          unsigned int    debug_id;
>>                  } afs;
>> +               struct {
>> +                       struct inode *fl_inode;
> Hi Xiubo,
>
> Nit: I think it could be just "inode", without the prefix which is
> already present in the union field name.

Okay, I can fix this in the next version.

Thanks.

- Xiubo


> Thanks,
>
>                  Ilya
>