xfs: push the AIL from memory reclaim and periodic sync

When we are short on memory, we want to expedite the cleaning of
dirty objects.  Hence when we run short on memory, we need to kick
the AIL flushing into action to clean as many dirty objects as
quickly as possible.  To implement this, sample the lsn of the log
item at the head of the AIL and use that as the push target for the
AIL flush.

Further, we keep items in the AIL that are dirty that are not
tracked any other way, so we can get objects sitting in the AIL that
don't get written back until the AIL is pushed. Hence to get the
filesystem to the idle state, we might need to push the AIL to flush
out any remaining dirty objects sitting in the AIL. This requires
the same push mechanism as the reclaim push.

This patch also renames xfs_trans_ail_tail() to xfs_ail_min_lsn() to
match the new xfs_ail_max_lsn() function introduced in this patch.
Similarly for xfs_trans_ail_push -> xfs_ail_push.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Alex Elder <aelder@sgi.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 25efa9b8a602..24643169e632 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -761,7 +761,7 @@ xfs_log_need_covered(xfs_mount_t *mp)
                 break;
         case XLOG_STATE_COVER_NEED:
         case XLOG_STATE_COVER_NEED2:
-                if (!xfs_trans_ail_tail(log->l_ailp) &&
+                if (!xfs_ail_min_lsn(log->l_ailp) &&
                     xlog_iclogs_empty(log)) {
                         if (log->l_covered_state == XLOG_STATE_COVER_NEED)
                                 log->l_covered_state = XLOG_STATE_COVER_DONE;
@@ -801,7 +801,7 @@ xlog_assign_tail_lsn(
         xfs_lsn_t               tail_lsn;
         struct log              *log = mp->m_log;
 
-        tail_lsn = xfs_trans_ail_tail(mp->m_ail);
+        tail_lsn = xfs_ail_min_lsn(mp->m_ail);
         if (!tail_lsn)
                 tail_lsn = atomic64_read(&log->l_last_sync_lsn);
 
@@ -1239,7 +1239,7 @@ xlog_grant_push_ail(
          * the filesystem is shutting down.
          */
         if (!XLOG_FORCED_SHUTDOWN(log))
-                xfs_trans_ail_push(log->l_ailp, threshold_lsn);
+                xfs_ail_push(log->l_ailp, threshold_lsn);
 }
 
 /*