From: Yafang Shao <laoar.shao@gmail.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@infradead.org>,
Michal Hocko <mhocko@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Howells <dhowells@redhat.com>,
jlayton@redhat.com, linux-fsdevel@vger.kernel.org,
linux-cachefs@redhat.com, linux-xfs@vger.kernel.org,
Linux MM <linux-mm@kvack.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v12 3/4] xfs: refactor the usage around xfs_trans_context_{set,clear}
Date: Sun, 13 Dec 2020 17:09:02 +0800 [thread overview]
Message-ID: <CALOAHbD_DK9w=s9RDsVBNaYwgeRi4UUEGDHFb3zEsqh_V8gLMA@mail.gmail.com> (raw)
In-Reply-To: <20201209195235.GN1943235@magnolia>
On Thu, Dec 10, 2020 at 3:52 AM Darrick J. Wong <darrick.wong@oracle.com> 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@oracle.com>
> > Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Dave Chinner <david@fromorbit.com>
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > ---
> > 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()
> --D
>
> > + xfs_trans_context_clear(tp);
> > +
> > trace_xfs_trans_free(tp, _RET_IP_);
> > if (!(tp->t_flags & XFS_TRANS_NO_WRITECOUNT))
> > sb_end_intwrite(tp->t_mountp->m_super);
> > @@ -153,9 +164,6 @@ xfs_trans_reserve(
> > int error = 0;
> > bool rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;
> >
> > - /* Mark this thread as being in a transaction */
> > - xfs_trans_context_set(tp);
> > -
> > /*
> > * Attempt to reserve the needed disk blocks by decrementing
> > * the number needed from the number available. This will
> > @@ -163,10 +171,9 @@ xfs_trans_reserve(
> > */
> > if (blocks > 0) {
> > error = xfs_mod_fdblocks(mp, -((int64_t)blocks), rsvd);
> > - if (error != 0) {
> > - xfs_trans_context_clear(tp);
> > + if (error != 0)
> > return -ENOSPC;
> > - }
> > +
> > tp->t_blk_res += blocks;
> > }
> >
> > @@ -241,8 +248,6 @@ xfs_trans_reserve(
> > tp->t_blk_res = 0;
> > }
> >
> > - xfs_trans_context_clear(tp);
> > -
> > return error;
> > }
> >
> > @@ -284,6 +289,8 @@ xfs_trans_alloc(
> > INIT_LIST_HEAD(&tp->t_dfops);
> > tp->t_firstblock = NULLFSBLOCK;
> >
> > + /* Mark this thread as being in a transaction */
> > + xfs_trans_context_set(tp);
> > error = xfs_trans_reserve(tp, resp, blocks, rtextents);
> > if (error) {
> > xfs_trans_cancel(tp);
> > @@ -878,7 +885,6 @@ __xfs_trans_commit(
> >
> > xfs_log_commit_cil(mp, tp, &commit_lsn, regrant);
> >
> > - xfs_trans_context_clear(tp);
> > xfs_trans_free(tp);
> >
> > /*
> > @@ -911,7 +917,6 @@ __xfs_trans_commit(
> > tp->t_ticket = NULL;
> > }
> >
> > - xfs_trans_context_clear(tp);
> > xfs_trans_free_items(tp, !!error);
> > xfs_trans_free(tp);
> >
> > @@ -971,9 +976,6 @@ xfs_trans_cancel(
> > tp->t_ticket = NULL;
> > }
> >
> > - /* mark this thread as no longer being in a transaction */
> > - xfs_trans_context_clear(tp);
> > -
> > xfs_trans_free_items(tp, dirty);
> > xfs_trans_free(tp);
> > }
> > --
> > 2.18.4
> >
--
Thanks
Yafang
next prev parent reply other threads:[~2020-12-13 9:09 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 13:11 [PATCH v12 0/4] xfs: avoid transaction reservation recursion Yafang Shao
2020-12-09 13:11 ` [PATCH v12 1/4] mm: Add become_kswapd and restore_kswapd Yafang Shao
2020-12-09 13:11 ` [PATCH v12 2/4] xfs: use memalloc_nofs_{save,restore} in xfs transaction Yafang Shao
2020-12-09 13:11 ` [PATCH v12 3/4] xfs: refactor the usage around xfs_trans_context_{set,clear} Yafang Shao
2020-12-09 19:52 ` Darrick J. Wong
2020-12-13 9:09 ` Yafang Shao [this message]
2020-12-14 21:08 ` Dave Chinner
2020-12-15 0:42 ` Yafang Shao
2020-12-15 1:12 ` Dave Chinner
2020-12-15 4:39 ` Yafang Shao
2020-12-09 13:11 ` [PATCH v12 4/4] xfs: use current->journal_info to avoid transaction reservation recursion Yafang Shao
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