@@ -297,6 +297,13 @@ xfs_qm_qoff_logitem_push(
struct xfs_log_item *lip,
struct list_head *buffer_list)
{
+ struct xfs_log_item *mlip = xfs_ail_min(lip->li_ailp);
+
+ if (test_bit(XFS_LI_RELOG, &lip->li_flags) &&
+ !test_bit(XFS_LI_RELOGGED, &lip->li_flags) &&
+ !XFS_LSN_CMP(lip->li_lsn, mlip->li_lsn))
+ return XFS_ITEM_RELOG;
+
return XFS_ITEM_LOCKED;
}
@@ -18,6 +18,7 @@
#include "xfs_quota.h"
#include "xfs_qm.h"
#include "xfs_icache.h"
+#include "xfs_trans_priv.h"
STATIC int
xfs_qm_log_quotaoff(
@@ -37,6 +38,7 @@ xfs_qm_log_quotaoff(
qoffi = xfs_trans_get_qoff_item(tp, NULL, flags & XFS_ALL_QUOTA_ACCT);
xfs_trans_log_quotaoff_item(tp, qoffi);
+ xfs_trans_enable_relog(&qoffi->qql_item);
spin_lock(&mp->m_sb_lock);
mp->m_sb.sb_qflags = (mp->m_qflags & ~(flags)) & XFS_MOUNT_QUOTA_ALL;
@@ -69,6 +71,13 @@ xfs_qm_log_quotaoff_end(
int error;
struct xfs_qoff_logitem *qoffi;
+ /*
+ * startqoff must be in the AIL and not the CIL when the end intent
+ * commits to ensure it is not readded to the AIL out of order. Wait on
+ * relog activity to drain to isolate startqoff to the AIL.
+ */
+ xfs_trans_disable_relog(&startqoff->qql_item, true);
+
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_qm_equotaoff, 0, 0, 0, &tp);
if (error)
return error;
The quotaoff operation has a rare but longstanding deadlock vector in terms of how the operation is logged. A quotaoff start intent is logged (synchronously) at the onset to ensure recovery can continue with the operation before in-core changes are made. This quotaoff intent pins the log tail while the quotaoff sequence scans and purges dquots from all in-core inodes. While this operation generally doesn't generate much log traffic on its own, it can be time consuming. If unrelated filesystem activity consumes remaining log space before quotaoff is able to allocate the quotaoff end intent, the filesystem locks up indefinitely. quotaoff cannot allocate the end intent before the scan because the latter can result in transaction allocation itself in certain indirect cases (releasing an inode, for example). Further, rolling the original transaction is difficult because the scanning work occurs multiple layers down where caller context is lost and not much information is available to determine how often to roll the transaction. To address this problem, enable automatic relogging of the quotaoff start intent. Trigger a relog whenever AIL pushing finds the item at the tail of the log. When complete, wait for relogging to complete as the end intent expects to be able to permanently remove the start intent from the log subsystem. This ensures that the log tail is kept moving during a particularly long quotaoff operation and avoids deadlock via unrelated fs activity. Signed-off-by: Brian Foster <bfoster@redhat.com> --- fs/xfs/xfs_dquot_item.c | 7 +++++++ fs/xfs/xfs_qm_syscalls.c | 9 +++++++++ 2 files changed, 16 insertions(+)