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

[Sunil Mushran]

Tao Ma wrote:
>
> 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. ;)

I'm confused. How will the OCFS2_ORPHANED_FL be set for reflinked inodes
if the node crashed?