Re: [PATCH v3 10/17] xfs: acquire ->ail_lock from xfs_trans_ail_delete()

[Brian Foster <bfoster@redhat.com>]

On Thu, Apr 30, 2020 at 11:52:50AM -0700, Darrick J. Wong wrote:
> On Wed, Apr 29, 2020 at 01:21:46PM -0400, Brian Foster wrote:
> > Several callers acquire the lock just prior to the call. Callers
> > that require ->ail_lock for other purposes already check IN_AIL
> > state and thus don't require the additional shutdown check in the
> > helper. Push the lock down into xfs_trans_ail_delete(), open code
> > the instances that still acquire it, and remove the unnecessary ailp
> > parameter.
> > 
> > Signed-off-by: Brian Foster <bfoster@redhat.com>
> 
> Ahh, this and the next few patches are a split of a larger patch from
> the last posting.  So I guess the point of this is to reduce parameter
> passing and get rid of the SHUTDOWN_* flags?
> 

Yeah, the point is just to simplify and ultimately combine these two odd
helpers into one. It was originally easier for me to work it all out in
one change/patch, but Christoph preferred to see it split up. Ultimately
it's easier for a reviewer to squash multiple simple patches than take a
potentially confusing one apart, so I broke it back out into these 3 or
4...

Brian

> Looks decent to me, regardless...
> 
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> --D
> 
> > ---
> >  fs/xfs/xfs_buf_item.c   | 27 +++++++++++----------------
> >  fs/xfs/xfs_dquot.c      |  6 ++++--
> >  fs/xfs/xfs_trans_ail.c  |  3 ++-
> >  fs/xfs/xfs_trans_priv.h | 14 ++++++++------
> >  4 files changed, 25 insertions(+), 25 deletions(-)
> > 
> > diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
> > index 1f7acffc99ba..06e306b49283 100644
> > --- a/fs/xfs/xfs_buf_item.c
> > +++ b/fs/xfs/xfs_buf_item.c
> > @@ -410,7 +410,6 @@ xfs_buf_item_unpin(
> >  {
> >  	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);
> >  	xfs_buf_t		*bp = bip->bli_buf;
> > -	struct xfs_ail		*ailp = lip->li_ailp;
> >  	int			stale = bip->bli_flags & XFS_BLI_STALE;
> >  	int			freed;
> >  
> > @@ -452,10 +451,10 @@ xfs_buf_item_unpin(
> >  		}
> >  
> >  		/*
> > -		 * If we get called here because of an IO error, we may
> > -		 * or may not have the item on the AIL. xfs_trans_ail_delete()
> > -		 * will take care of that situation.
> > -		 * xfs_trans_ail_delete() drops the AIL lock.
> > +		 * If we get called here because of an IO error, we may or may
> > +		 * not have the item on the AIL. xfs_trans_ail_delete() will
> > +		 * take care of that situation. xfs_trans_ail_delete() drops
> > +		 * the AIL lock.
> >  		 */
> >  		if (bip->bli_flags & XFS_BLI_STALE_INODE) {
> >  			xfs_buf_do_callbacks(bp);
> > @@ -463,8 +462,7 @@ xfs_buf_item_unpin(
> >  			list_del_init(&bp->b_li_list);
> >  			bp->b_iodone = NULL;
> >  		} else {
> > -			spin_lock(&ailp->ail_lock);
> > -			xfs_trans_ail_delete(ailp, lip, SHUTDOWN_LOG_IO_ERROR);
> > +			xfs_trans_ail_delete(lip, SHUTDOWN_LOG_IO_ERROR);
> >  			xfs_buf_item_relse(bp);
> >  			ASSERT(bp->b_log_item == NULL);
> >  		}
> > @@ -1205,22 +1203,19 @@ xfs_buf_iodone(
> >  	struct xfs_buf		*bp,
> >  	struct xfs_log_item	*lip)
> >  {
> > -	struct xfs_ail		*ailp = lip->li_ailp;
> > -
> >  	ASSERT(BUF_ITEM(lip)->bli_buf == bp);
> >  
> >  	xfs_buf_rele(bp);
> >  
> >  	/*
> > -	 * If we are forcibly shutting down, this may well be
> > -	 * off the AIL already. That's because we simulate the
> > -	 * log-committed callbacks to unpin these buffers. Or we may never
> > -	 * have put this item on AIL because of the transaction was
> > -	 * aborted forcibly. xfs_trans_ail_delete() takes care of these.
> > +	 * If we are forcibly shutting down, this may well be off the AIL
> > +	 * already. That's because we simulate the log-committed callbacks to
> > +	 * unpin these buffers. Or we may never have put this item on AIL
> > +	 * because of the transaction was aborted forcibly.
> > +	 * xfs_trans_ail_delete() takes care of these.
> >  	 *
> >  	 * Either way, AIL is useless if we're forcing a shutdown.
> >  	 */
> > -	spin_lock(&ailp->ail_lock);
> > -	xfs_trans_ail_delete(ailp, lip, SHUTDOWN_CORRUPT_INCORE);
> > +	xfs_trans_ail_delete(lip, SHUTDOWN_CORRUPT_INCORE);
> >  	xfs_buf_item_free(BUF_ITEM(lip));
> >  }
> > diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
> > index ffe607733c50..5fb65f43b980 100644
> > --- a/fs/xfs/xfs_dquot.c
> > +++ b/fs/xfs/xfs_dquot.c
> > @@ -1021,6 +1021,7 @@ xfs_qm_dqflush_done(
> >  	struct xfs_dq_logitem	*qip = (struct xfs_dq_logitem *)lip;
> >  	struct xfs_dquot	*dqp = qip->qli_dquot;
> >  	struct xfs_ail		*ailp = lip->li_ailp;
> > +	xfs_lsn_t		tail_lsn;
> >  
> >  	/*
> >  	 * We only want to pull the item from the AIL if its
> > @@ -1034,10 +1035,11 @@ xfs_qm_dqflush_done(
> >  	    ((lip->li_lsn == qip->qli_flush_lsn) ||
> >  	     test_bit(XFS_LI_FAILED, &lip->li_flags))) {
> >  
> > -		/* xfs_trans_ail_delete() drops the AIL lock. */
> >  		spin_lock(&ailp->ail_lock);
> >  		if (lip->li_lsn == qip->qli_flush_lsn) {
> > -			xfs_trans_ail_delete(ailp, lip, SHUTDOWN_CORRUPT_INCORE);
> > +			/* xfs_ail_update_finish() drops the AIL lock */
> > +			tail_lsn = xfs_ail_delete_one(ailp, lip);
> > +			xfs_ail_update_finish(ailp, tail_lsn);
> >  		} else {
> >  			/*
> >  			 * Clear the failed state since we are about to drop the
> > diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
> > index 2574d01e4a83..cfba691664c7 100644
> > --- a/fs/xfs/xfs_trans_ail.c
> > +++ b/fs/xfs/xfs_trans_ail.c
> > @@ -864,13 +864,14 @@ xfs_ail_delete_one(
> >   */
> >  void
> >  xfs_trans_ail_delete(
> > -	struct xfs_ail		*ailp,
> >  	struct xfs_log_item	*lip,
> >  	int			shutdown_type)
> >  {
> > +	struct xfs_ail		*ailp = lip->li_ailp;
> >  	struct xfs_mount	*mp = ailp->ail_mount;
> >  	xfs_lsn_t		tail_lsn;
> >  
> > +	spin_lock(&ailp->ail_lock);
> >  	if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
> >  		spin_unlock(&ailp->ail_lock);
> >  		if (!XFS_FORCED_SHUTDOWN(mp)) {
> > diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h
> > index 35655eac01a6..e4362fb8d483 100644
> > --- a/fs/xfs/xfs_trans_priv.h
> > +++ b/fs/xfs/xfs_trans_priv.h
> > @@ -94,8 +94,7 @@ xfs_trans_ail_update(
> >  xfs_lsn_t xfs_ail_delete_one(struct xfs_ail *ailp, struct xfs_log_item *lip);
> >  void xfs_ail_update_finish(struct xfs_ail *ailp, xfs_lsn_t old_lsn)
> >  			__releases(ailp->ail_lock);
> > -void xfs_trans_ail_delete(struct xfs_ail *ailp, struct xfs_log_item *lip,
> > -		int shutdown_type);
> > +void xfs_trans_ail_delete(struct xfs_log_item *lip, int shutdown_type);
> >  
> >  static inline void
> >  xfs_trans_ail_remove(
> > @@ -103,13 +102,16 @@ xfs_trans_ail_remove(
> >  	int			shutdown_type)
> >  {
> >  	struct xfs_ail		*ailp = lip->li_ailp;
> > +	xfs_lsn_t		tail_lsn;
> >  
> >  	spin_lock(&ailp->ail_lock);
> > -	/* xfs_trans_ail_delete() drops the AIL lock */
> > -	if (test_bit(XFS_LI_IN_AIL, &lip->li_flags))
> > -		xfs_trans_ail_delete(ailp, lip, shutdown_type);
> > -	else
> > +	/* xfs_ail_update_finish() drops the AIL lock */
> > +	if (test_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
> > +		tail_lsn = xfs_ail_delete_one(ailp, lip);
> > +		xfs_ail_update_finish(ailp, tail_lsn);
> > +	} else {
> >  		spin_unlock(&ailp->ail_lock);
> > +	}
> >  }
> >  
> >  void			xfs_ail_push(struct xfs_ail *, xfs_lsn_t);
> > -- 
> > 2.21.1
> > 
>