On Sun, Dec 13, 2020 at 05:09:02PM +0800, Yafang Shao wrote: > On Thu, Dec 10, 2020 at 3:52 AM Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: > > > > On Wed, Dec 09, 2020 at 09:11:45PM +0800, Yafang Shao wrote: > > > The xfs_trans context should be active after it is allocated, and > > > deactive when it is freed. > > > > > > So these two helpers are refactored as, > > > - xfs_trans_context_set() > > > Used in xfs_trans_alloc() > > > - xfs_trans_context_clear() > > > Used in xfs_trans_free() > > > > > > This patch is based on Darrick's work to fix the issue in xfs/141 in the > > > earlier version. [1] > > > > > > 1. https://lore.kernel.org/linux-xfs/20201104001649.GN7123@magnolia > > > > > > Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > > Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> > > > Cc: Christoph Hellwig <hch@xxxxxx> > > > Cc: Dave Chinner <david@xxxxxxxxxxxxx> > > > Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx> > > > --- > > > fs/xfs/xfs_trans.c | 28 +++++++++++++++------------- > > > 1 file changed, 15 insertions(+), 13 deletions(-) > > > > > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > > > index 11d390f0d3f2..4f4645329bb2 100644 > > > --- a/fs/xfs/xfs_trans.c > > > +++ b/fs/xfs/xfs_trans.c > > > @@ -67,6 +67,17 @@ xfs_trans_free( > > > xfs_extent_busy_sort(&tp->t_busy); > > > xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false); > > > > > > + > > > + /* Detach the transaction from this thread. */ > > > + ASSERT(current->journal_info != NULL); > > > + /* > > > + * The PF_MEMALLOC_NOFS is bound to the transaction itself instead > > > + * of the reservation, so we need to check if tp is still the > > > + * current transaction before clearing the flag. > > > + */ > > > + if (current->journal_info == tp) > > > > Um, you don't start setting journal_info until the next patch, so this > > means that someone who lands on this commit with git bisect will have a > > xfs with broken logic. > > > > Because this is the patch that changes where we set and restore NOFS > > context, I think you have to introduce xfs_trans_context_swap here, > > and not in the next patch. > > > > Thanks for the review. I will change it in the next version. > > > I also think the _swap routine has to move the old NOFS state to the > > new transaction's t_pflags, > > Sure > > > and then set NOFS in the old transaction's > > t_pflags so that when we clear the context on the old transaction we > > don't actually change the thread's NOFS state. > > > > Both thread's NOFS state and thead's journal_info state can't be > changed in that case, right ? > So should it better be, > > __xfs_trans_commit(tp, regrant) > xfs_trans_free(tp, regrant) > if (!regrant). // don't clear the xfs_trans_context if > regrant is true. > xfs_trans_context_clear() No. You are trying to make this way more complex than it needs to be. The logic in the core XFS code is *already correct* and all we need to do is move that logic to wrapper functions, then slightly modify the implementation inside the wrapper functions. That is, xfs_trans_context_clear() should end up like this: static inline void xfs_trans_context_clear(struct xfs_trans *tp) { /* * If xfs_trans_context_swap() handed the NOFS context to a * new transaction we do not clear the context here. */ if (current->journal_info != tp) return; current->journal_info = NULL; memalloc_nofs_restore(tp->t_pflags); } -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
