[Ocfs2-devel] [PATCH] ocfs2: Take inode cluster lock before moving reflinked inode from orphan dir

[Joseph Qi]

On 18/3/31 01:42, Ashish Samant wrote:
> While reflinking an inode, we create a new inode in orphan directory, then
> take EX lock on it, reflink the original inode to orphan inode and release
> EX lock. Once the lock is released another node might request it in PR mode
> which causes downconvert of the lock to PR mode.
> 
> Later we attempt to initialize security acl for the orphan inode and move
> it to the reflink destination. However, while doing this we dont take EX
> lock on the inode. So effectively, we are doing this and accessing the
> journal for this inode while holding PR lock. While accessing the journal,
> we make
> 
> ci->ci_last_trans = journal->j_trans_id
> 
> At this point, if there is another downconvert request on this inode from
> another node (PR->NL), we will trip on the following condition in
> ocfs2_ci_checkpointed()
> 
> BUG_ON(lockres->l_level != DLM_LOCK_EX && !checkpointed);
> 
> because we hold the lock in PR mode and journal->j_trans_id is not greater
> than ci_last_trans for the inode.
> 
> Fix this by taking orphan inode cluster lock in EX mode before
> initializing security and moving orphan inode to reflink destination.
> Use the __tracker variant while taking inode lock to avoid recursive
> locking in the ocfs2_init_security_and_acl() call chain.
> 
> Signed-off-by: Ashish Samant <ashish.samant at oracle.com>

Looks good.
Reviewed-by: Joseph Qi <jiangqi903 at gmail.com>