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-rw-r--r--fs/xfs/xfs_log.c29
1 files changed, 28 insertions, 1 deletions
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 3e0a105b6cc9..4dbe063217ac 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -214,15 +214,42 @@ xlog_grant_head_wake(
{
struct xlog_ticket *tic;
int need_bytes;
+ bool woken_task = false;
list_for_each_entry(tic, &head->waiters, t_queue) {
+
+ /*
+ * There is a chance that the size of the CIL checkpoints in
+ * progress at the last AIL push target calculation resulted in
+ * limiting the target to the log head (l_last_sync_lsn) at the
+ * time. This may not reflect where the log head is now as the
+ * CIL checkpoints may have completed.
+ *
+ * Hence when we are woken here, it may be that the head of the
+ * log that has moved rather than the tail. As the tail didn't
+ * move, there still won't be space available for the
+ * reservation we require. However, if the AIL has already
+ * pushed to the target defined by the old log head location, we
+ * will hang here waiting for something else to update the AIL
+ * push target.
+ *
+ * Therefore, if there isn't space to wake the first waiter on
+ * the grant head, we need to push the AIL again to ensure the
+ * target reflects both the current log tail and log head
+ * position before we wait for the tail to move again.
+ */
+
need_bytes = xlog_ticket_reservation(log, head, tic);
- if (*free_bytes < need_bytes)
+ if (*free_bytes < need_bytes) {
+ if (!woken_task)
+ xlog_grant_push_ail(log, need_bytes);
return false;
+ }
*free_bytes -= need_bytes;
trace_xfs_log_grant_wake_up(log, tic);
wake_up_process(tic->t_task);
+ woken_task = true;
}
return true;