Merge tag 'for-linus-v3.6-rc1' of git://oss.sgi.com/xfs/xfs

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / xfs / xfs_trans_ail.c

diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index 9c514483e59924eecb6e64c95bb198af2de5e606..6011ee6613396f9b325418fde28e07c2147f0e5e 100644 (file)
--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -383,6 +383,12 @@ xfsaild_push(
        }
 
        spin_lock(&ailp->xa_lock);
+
+       /* barrier matches the xa_target update in xfs_ail_push() */
+       smp_rmb();
+       target = ailp->xa_target;
+       ailp->xa_target_prev = target;
+
        lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->xa_last_pushed_lsn);
        if (!lip) {
                /*
@@ -397,7 +403,6 @@ xfsaild_push(
        XFS_STATS_INC(xs_push_ail);
 
        lsn = lip->li_lsn;
-       target = ailp->xa_target;
        while ((XFS_LSN_CMP(lip->li_lsn, target) <= 0)) {
                int     lock_result;
 
@@ -527,8 +532,32 @@ xfsaild(
                        __set_current_state(TASK_KILLABLE);
                else
                        __set_current_state(TASK_INTERRUPTIBLE);
-               schedule_timeout(tout ?
-                                msecs_to_jiffies(tout) : MAX_SCHEDULE_TIMEOUT);
+
+               spin_lock(&ailp->xa_lock);
+
+               /*
+                * Idle if the AIL is empty and we are not racing with a target
+                * update. We check the AIL after we set the task to a sleep
+                * state to guarantee that we either catch an xa_target update
+                * or that a wake_up resets the state to TASK_RUNNING.
+                * Otherwise, we run the risk of sleeping indefinitely.
+                *
+                * The barrier matches the xa_target update in xfs_ail_push().
+                */
+               smp_rmb();
+               if (!xfs_ail_min(ailp) &&
+                   ailp->xa_target == ailp->xa_target_prev) {
+                       spin_unlock(&ailp->xa_lock);
+                       schedule();
+                       tout = 0;
+                       continue;
+               }
+               spin_unlock(&ailp->xa_lock);
+
+               if (tout)
+                       schedule_timeout(msecs_to_jiffies(tout));
+
+               __set_current_state(TASK_RUNNING);
 
                try_to_freeze();