On Wed, Dec 9, 2020 at 11:53 AM Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: > > On Wed, Dec 09, 2020 at 09:47:38AM +0800, Yafang Shao wrote: > > On Wed, Dec 9, 2020 at 2:59 AM Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: > > > > > > On Tue, Dec 08, 2020 at 08:28:23PM +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 | 20 +++++++------------- > > > > 1 file changed, 7 insertions(+), 13 deletions(-) > > > > > > > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > > > > index 11d390f0d3f2..fe20398a214e 100644 > > > > --- a/fs/xfs/xfs_trans.c > > > > +++ b/fs/xfs/xfs_trans.c > > > > @@ -67,6 +67,9 @@ 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. */ > > > > + xfs_trans_context_clear(tp); > > > > > > Don't you need to check if tp is still the current transaction before > > > you clear PF_MEMALLOC_NOFS, now that the NOFS is bound to the lifespan > > > of the transaction itself instead of the reservation? > > > > > > > The current->journal_info is always the same with tp here in my verification. > > I don't know in which case they are different. > > I don't know why you changed it from the previous version. > I should explain it in the change log. Sorry about that. > > It would be better if you could explain in detail. Anyway I can add > > the check with your comment in the next version. > > xfs_trans_alloc is called to allocate a transaction. We set _NOFS and > save the old flags (which don't contain _NOFS) to this transaction. > > thread logs some changes and calls xfs_trans_roll. > > xfs_trans_roll calls xfs_trans_dup to duplicate the old transaction. > > xfs_trans_dup allocates a new transaction, which sets PF_MEMALLOC_NOFS > and saves the current context flags (in which _NOFS is set) in the new > transaction. > > xfs_trans_roll then commits the old transaction > > xfs_trans_commit frees the old transaction > > xfs_trans_free restores the old context (which didn't have _NOFS) and > now we've dropped NOFS incorrectly > > now we move on with the new transaction, but in the wrong NOFS mode. > > note that this becomes a lot more obvious once you start fiddling with > current->journal_info in the last patch. > Many thanks for the detailed explanation. I missed the rolling transaction. I will add this check in the next version. > --D > > > > > > > > > > + > > > > 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 +156,6 @@ 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 +163,9 @@ 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 +240,6 @@ xfs_trans_reserve( > > > > tp->t_blk_res = 0; > > > > } > > > > > > > > - xfs_trans_context_clear(tp); > > > > - > > > > return error; > > > > } > > > > > > > > @@ -284,6 +281,8 @@ 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 +877,6 @@ __xfs_trans_commit( > > > > > > > > xfs_log_commit_cil(mp, tp, &commit_lsn, regrant); > > > > > > > > - xfs_trans_context_clear(tp); > > > > xfs_trans_free(tp); > > > > > > > > /* > > > > @@ -911,7 +909,6 @@ __xfs_trans_commit( > > > > tp->t_ticket = NULL; > > > > } > > > > > > > > - xfs_trans_context_clear(tp); > > > > xfs_trans_free_items(tp, !!error); > > > > xfs_trans_free(tp); > > > > > > > > @@ -971,9 +968,6 @@ 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 -- Thanks Yafang
