On Fri, Aug 25, 2017 at 10:04:01AM -0700, Darrick J. Wong wrote:
> On Fri, Aug 25, 2017 at 02:07:52PM +0200, Carlos Maiolino wrote:
> > Hi,
> >
> > Once the fix for inode item writeback errors is already queued
> > (d3a304b62), I believe it's time to fix the same problem in dquot code.
> >
> > Although there were no reports of users hitting this bug in dquot code
> > (at least none I've seen), the bug is there and I was already planning
> > to fix it when the correct approach to fix the inodes part was decided.
> >
> > So, this is an RFC patch to fix the same problem in dquot code,
> > regarding failed buffers being unable to be resubmitted once they are
> > flush locked.
> >
> > The semantics are quite similar to inode items path, although during
> > xfs_qm_dqflush_done(), I'm not sure if the changes I made are correct.
> >
> > Comments much appreciated :)
> >
> >
> > BTW, This patch should be applied only over branch xfs-4.14-merge, it requires
> > my previous patches, which are not in the master branch yet.
>
> Looks ok, but is there an xfstests case to cover this?
Then I tried compiling it, which broke, and then I went digging more than
I would've for an RFC:
> --D
>
> >
> > Cheers.
> >
> > Signed-off-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
> > ---
> > fs/xfs/xfs_dquot.c | 11 ++++++++---
> > fs/xfs/xfs_dquot_item.c | 37 +++++++++++++++++++++++++++++++++++--
> > 2 files changed, 43 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
> > index fd2ef8c2c9a7..8198c20212a2 100644
> > --- a/fs/xfs/xfs_dquot.c
> > +++ b/fs/xfs/xfs_dquot.c
> > @@ -987,14 +987,19 @@ xfs_qm_dqflush_done(
> > * holding the lock before removing the dquot from the AIL.
> > */
> > if ((lip->li_flags & XFS_LI_IN_AIL) &&
> > - lip->li_lsn == qip->qli_flush_lsn) {
> > + (lip->li_lsn == qip->qli_flush_lsn) ||
> > + lip->li_flags & XFS_LI_FAILED) {
...come to think of it, shouldn't there be a couple extra pairs of parentheses
in this somewhere?...
> >
> > /* xfs_trans_ail_delete() drops the AIL lock. */
> > spin_lock(&ailp->xa_lock);
> > - if (lip->li_lsn == qip->qli_flush_lsn)
> > + if (lip->li_lsn == qip->qli_flush_lsn) {
> > xfs_trans_ail_delete(ailp, lip, SHUTDOWN_CORRUPT_INCORE);
> > - else
> > + } else if (lip->li_flags & XFS_LI_FAILED) {
> > + xfs_clear_li_failed(lip);
> > spin_unlock(&ailp->xa_lock);
> > + } else {
> > + spin_unlock(&ailp->xa_lock);
> > + }
> > }
> >
> > /*
> > diff --git a/fs/xfs/xfs_dquot_item.c b/fs/xfs/xfs_dquot_item.c
> > index 2c7a1629e064..35fd6d71bc42 100644
> > --- a/fs/xfs/xfs_dquot_item.c
> > +++ b/fs/xfs/xfs_dquot_item.c
> > @@ -137,6 +137,23 @@ xfs_qm_dqunpin_wait(
> > wait_event(dqp->q_pinwait, (atomic_read(&dqp->q_pincount) == 0));
> > }
> >
> > +/*
> > + * Callback used to mark a buffer with XFS_LI_FAILED when items in the buffer
> > + * have been failed during writeback
> > + *
> > + * this informs the AIL that the dquot is already flush locked on the next push,
> > + * and acquires a hold on the buffer to ensure that it isn't reclaimed before
> > + * dirty data makes it to disk.
> > + */
> > +STATIC void
> > +xfs_dquot_item_error(
> > + struct xfs_log_item *lip,
> > + struct xfs_buf *bp)
> > +{
> > + ASSERT(XFS_DQ_IS_LOCKED(DQUOT_ITEM(lip)->qli_item));
...and isn't this qli_dquot, not qli_item?
(Does this compile at all?)
--D
> > + xfs_set_li_failed(lip, bp);
> > +}
> > +
> > STATIC uint
> > xfs_qm_dquot_logitem_push(
> > struct xfs_log_item *lip,
> > @@ -144,13 +161,28 @@ xfs_qm_dquot_logitem_push(
> > __acquires(&lip->li_ailp->xa_lock)
> > {
> > struct xfs_dquot *dqp = DQUOT_ITEM(lip)->qli_dquot;
> > - struct xfs_buf *bp = NULL;
> > + struct xfs_buf *bp = lip->li_buf;
> > uint rval = XFS_ITEM_SUCCESS;
> > int error;
> >
> > if (atomic_read(&dqp->q_pincount) > 0)
> > return XFS_ITEM_PINNED;
> >
> > + /*
> > + * The buffer containing this item failed to be written back
> > + * previously. Resubmit the buffer for IO
> > + */
> > + if (lip->li_flags & XFS_LI_FAILED) {
> > + if (!xfs_buf_trylock(bp))
> > + return XFS_ITEM_LOCKED;
> > +
> > + if (!xfs_buf_resubmit_failed_buffers(bp, lip, buffer_list))
> > + rval = XFS_ITEM_FLUSHING;
> > +
> > + xfs_buf_unlock(bp);
> > + return rval;
> > + }
> > +
> > if (!xfs_dqlock_nowait(dqp))
> > return XFS_ITEM_LOCKED;
> >
> > @@ -242,7 +274,8 @@ static const struct xfs_item_ops xfs_dquot_item_ops = {
> > .iop_unlock = xfs_qm_dquot_logitem_unlock,
> > .iop_committed = xfs_qm_dquot_logitem_committed,
> > .iop_push = xfs_qm_dquot_logitem_push,
> > - .iop_committing = xfs_qm_dquot_logitem_committing
> > + .iop_committing = xfs_qm_dquot_logitem_committing,
> > + .iop_error = xfs_dquot_item_error
> > };
> >
> > /*
> > --
> > 2.13.5
> >
> > --
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