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?
--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) {
>
> /* 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));
> + 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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