On Thu, May 11, 2017 at 03:57:33PM +0200, Carlos Maiolino wrote:
> When a buffer has been failed during writeback, the inode items into it
> are kept flush locked, and are never resubmitted due the flush lock, so,
> if any buffer fails to be written, the items in AIL are never written to
> disk and never unlocked.
>
> This causes a filesystem to be unmountable due these items flush locked
> in AIL, but this also causes the items in AIL to never be written back,
> even when the IO device comes back to normal.
>
> I've been testing this patch with a DM-thin device, creating a
> filesystem larger than the real device.
>
> When writing enough data to fill the DM-thin device, XFS receives ENOSPC
> errors from the device, and keep spinning on xfsaild (when 'retry
> forever' configuration is set).
>
> At this point, the filesystem is unmountable because of the flush locked
> items in AIL, but worse, the items in AIL are never retried at all
> (once xfs_inode_item_push() will skip the items that are flush locked),
> even if the underlying DM-thin device is expanded to the proper size.
>
> This patch fixes both cases, retrying any item that has been failed
> previously, using the infra-structure provided by the previous patch.
>
> Signed-off-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
> ---
>
> This same problem is also possible in dquot code, but the fix is almost
> identical.
>
> I am not submitting a fix for dquot yet to avoid the need to create VX for both
> patches, once we agree with the solution, I'll submit a fix to dquot.
>
> fs/xfs/xfs_inode_item.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 53 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
> index 08cb7d1..583fa9e 100644
> --- a/fs/xfs/xfs_inode_item.c
> +++ b/fs/xfs/xfs_inode_item.c
> @@ -475,6 +475,21 @@ xfs_inode_item_unpin(
> wake_up_bit(&ip->i_flags, __XFS_IPINNED_BIT);
> }
>
> +STATIC void
> +xfs_inode_item_error(
> + struct xfs_log_item *lip,
> + unsigned int bflags)
> +{
> +
> + /*
> + * The buffer writeback containing this inode has been failed
> + * mark it as failed and unlock the flush lock, so it can be retried
> + * again
> + */
> + if (bflags & XBF_WRITE_FAIL)
> + lip->li_flags |= XFS_LI_FAILED;
> +}
> +
> STATIC uint
> xfs_inode_item_push(
> struct xfs_log_item *lip,
> @@ -517,8 +532,44 @@ xfs_inode_item_push(
> * the AIL.
> */
> if (!xfs_iflock_nowait(ip)) {
> + if (lip->li_flags & XFS_LI_FAILED) {
> +
> + struct xfs_dinode *dip;
> + struct xfs_log_item *next;
> + int error;
> +
> + error = xfs_imap_to_bp(ip->i_mount, NULL, &ip->i_imap,
> + &dip, &bp, XBF_TRYLOCK, 0);
> +
> + if (error) {
> + rval = XFS_ITEM_FLUSHING;
> + goto out_unlock;
> + }
> +
> + if (!(bp->b_flags & XBF_WRITE_FAIL)) {
> + rval = XFS_ITEM_FLUSHING;
> + xfs_buf_relse(bp);
> + goto out_unlock;
> + }
> +
> + while (lip != NULL) {
> + next = lip->li_bio_list;
> +
> + if (lip->li_flags & XFS_LI_FAILED)
> + lip->li_flags &= XFS_LI_FAILED;
Eric already pointed out that you probably intend to clear the flag
here..?
> + lip = next;
> + }
This whole hunk might be better off in a helper function (with the
comment Eric suggested as well).
Those points and the ->iop_error() thing aside, this otherwise seems Ok
to me.
Brian
> +
> + if (!xfs_buf_delwri_queue(bp, buffer_list))
> + rval = XFS_ITEM_FLUSHING;
> +
> + xfs_buf_relse(bp);
> + goto out_unlock;
> + }
> +
> rval = XFS_ITEM_FLUSHING;
> goto out_unlock;
> +
> }
>
> ASSERT(iip->ili_fields != 0 || XFS_FORCED_SHUTDOWN(ip->i_mount));
> @@ -622,7 +673,8 @@ static const struct xfs_item_ops xfs_inode_item_ops = {
> .iop_unlock = xfs_inode_item_unlock,
> .iop_committed = xfs_inode_item_committed,
> .iop_push = xfs_inode_item_push,
> - .iop_committing = xfs_inode_item_committing
> + .iop_committing = xfs_inode_item_committing,
> + .iop_error = xfs_inode_item_error
> };
>
>
> --
> 2.9.3
>
> --
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