[Ocfs2-devel] [PATCH 2/2] Ocfs2: Handle deletion of refcounted oprhan_inode correctly.

[Tao Ma]

tristan wrote:
> Tao Ma wrote:
>> Hi tristan,
>>
>> Tristan Ye wrote:
>>> Current ocfs2 semantic for reflinking a file firstly create a
>>> new orphan_inode in orphan_dir, then remove it to target dir
>>> after refcounting operation done, these 2 steps makes logic
>>> straightfoward, and guarantee a crash during reflinking can
>>> be replayed(half-refcounted inode can be removed), while it
>>> brings us another issue cause these 2 steps is acquiring the
>>> orphan_dir lock respectively, the problem is, orphan_scan()
>>> may detect the half-refcounted inode in orphan_dir as its
>>> proper candidates to wipe off in a later time. actually it's
>>> not of course, we'd handle this correctly.
>>>
>>> Signed-off-by: Tristan Ye <tristan.ye at oracle.com>
>>> ---
>>>  fs/ocfs2/inode.c |   32 ++++++++++++++++++++++++--------
>>>  1 files changed, 24 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
>>> index 88459bd..61fb546 100644
>>> --- a/fs/ocfs2/inode.c
>>> +++ b/fs/ocfs2/inode.c
>>> @@ -892,14 +892,30 @@ static int ocfs2_query_inode_wipe(struct inode 
>>> *inode,
>>>      di = (struct ocfs2_dinode *) di_bh->b_data;
>>>      if (!(di->i_flags & cpu_to_le32(OCFS2_ORPHANED_FL))) {
>>>          /* for lack of a better error? */
>>> -        status = -EEXIST;
>>> -        mlog(ML_ERROR,
>>> -             "Inode %llu (on-disk %llu) not orphaned! "
>>> -             "Disk flags  0x%x, inode flags 0x%x\n",
>>> -             (unsigned long long)oi->ip_blkno,
>>> -             (unsigned long long)le64_to_cpu(di->i_blkno),
>>> -             le32_to_cpu(di->i_flags), oi->ip_flags);
>>> -        goto bail;
>>> +        if (!(di->i_dyn_features &
>>> +              cpu_to_le16(OCFS2_HAS_REFCOUNT_FL))) {
>>> +            status = -EEXIST;
>>> +            mlog(ML_ERROR,
>>> +                 "Inode %llu (on-disk %llu) not orphaned! "
>>> +                 "Disk flags  0x%x, inode flags 0x%x\n",
>>> +                 (unsigned long long)oi->ip_blkno,
>>> +                 (unsigned long long)le64_to_cpu(di->i_blkno),
>>> +                 le32_to_cpu(di->i_flags), oi->ip_flags);
>>> +            goto bail;
>>> +        } else {
>>> +            /*
>>> +             * It did happen to us, though it's a rare case:
>>> +             * orphan_scan() detects the half-refcounted inode
>>> +             * in orphan_dir, and delete_inode() attempts to
>>> +             * wipe it after reflink operation done later. now
>>> +             * we're not allowed to delete such a valid inode,
>>> +             * instead, just bail out.
>>> +             */
>>> +            mlog(0, "Skipping delete of %llu because it's a "
>>> +                 "reflinked inode\n",
>>> +                 (unsigned long long)oi->ip_blkno);
>>> +            goto bail;
>>> +        }
>> We set i_dyn_features when when attach the tree to the file. This is 
>> very early. So I am curious why i_dyn_features can tell you whether 
>> this isn't a crashed reflink inode? Oh, you mean you will never delete 
>> a reflinked inode in orphan scan?
> 
> Tao,
> 
> Not exactly, if it's reflink operation was crashed somehow, it's 
> OCFS2_ORPHANED_FL must be set:), and if it was the case, we then will 
> never skip the deletion which is really needed.
oh, so this is really a hack for reflink. I am not sure whether it is 
appropriate. So let Joel decide whether it is OK or not. ;)

Regards,
Tao