Merge commit 'v2.6.39' into for-2.6.40/core

Since for-2.6.40/core was forked off the 2.6.39 devel tree, we've
had churn in the core area that makes it difficult to handle
patches for eg cfq or blk-throttle. Instead of requiring that they
be based in older versions with bugs that have been fixed later
in the rc cycle, merge in 2.6.39 final.

Also fixes up conflicts in the below files.

Conflicts:
	drivers/block/paride/pcd.c
	drivers/cdrom/viocd.c
	drivers/ide/ide-cd.c

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 26 insertions, 21 deletions

diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index acdb92f14d51..5fc2380092c8 100644
--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -346,20 +346,23 @@ xfs_ail_delete(
  */
 STATIC void
 xfs_ail_worker(
-        struct work_struct *work)
+        struct work_struct      *work)
 {
-        struct xfs_ail  *ailp = container_of(to_delayed_work(work),
+        struct xfs_ail          *ailp = container_of(to_delayed_work(work),
                                         struct xfs_ail, xa_work);
-        long            tout;
-        xfs_lsn_t       target =  ailp->xa_target;
-        xfs_lsn_t       lsn;
-        xfs_log_item_t  *lip;
-        int             flush_log, count, stuck;
-        xfs_mount_t     *mp = ailp->xa_mount;
+        xfs_mount_t             *mp = ailp->xa_mount;
         struct xfs_ail_cursor   *cur = &ailp->xa_cursors;
-        int             push_xfsbufd = 0;
+        xfs_log_item_t          *lip;
+        xfs_lsn_t               lsn;
+        xfs_lsn_t               target;
+        long                    tout = 10;
+        int                     flush_log = 0;
+        int                     stuck = 0;
+        int                     count = 0;
+        int                     push_xfsbufd = 0;
 
         spin_lock(&ailp->xa_lock);
+        target = ailp->xa_target;
         xfs_trans_ail_cursor_init(ailp, cur);
         lip = xfs_trans_ail_cursor_first(ailp, cur, ailp->xa_last_pushed_lsn);
         if (!lip || XFS_FORCED_SHUTDOWN(mp)) {
@@ -368,8 +371,7 @@ xfs_ail_worker(
                  */
                 xfs_trans_ail_cursor_done(ailp, cur);
                 spin_unlock(&ailp->xa_lock);
-                ailp->xa_last_pushed_lsn = 0;
-                return;
+                goto out_done;
         }
 
         XFS_STATS_INC(xs_push_ail);
@@ -386,8 +388,7 @@ xfs_ail_worker(
          * lots of contention on the AIL lists.
          */
         lsn = lip->li_lsn;
-        flush_log = stuck = count = 0;
-        while ((XFS_LSN_CMP(lip->li_lsn, target) < 0)) {
+        while ((XFS_LSN_CMP(lip->li_lsn, target) <= 0)) {
                 int     lock_result;
                 /*
                  * If we can lock the item without sleeping, unlock the AIL
@@ -480,21 +481,25 @@ xfs_ail_worker(
         }
 
         /* assume we have more work to do in a short while */
-        tout = 10;
+out_done:
         if (!count) {
                 /* We're past our target or empty, so idle */
                 ailp->xa_last_pushed_lsn = 0;
 
                 /*
-                 * Check for an updated push target before clearing the
-                 * XFS_AIL_PUSHING_BIT. If the target changed, we've got more
-                 * work to do. Wait a bit longer before starting that work.
+                 * We clear the XFS_AIL_PUSHING_BIT first before checking
+                 * whether the target has changed. If the target has changed,
+                 * this pushes the requeue race directly onto the result of the
+                 * atomic test/set bit, so we are guaranteed that either the
+                 * the pusher that changed the target or ourselves will requeue
+                 * the work (but not both).
                  */
+                clear_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags);
                 smp_rmb();
-                if (ailp->xa_target == target) {
-                        clear_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags);
+                if (XFS_LSN_CMP(ailp->xa_target, target) == 0 ||
+                    test_and_set_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags))
                         return;
-                }
+
                 tout = 50;
         } else if (XFS_LSN_CMP(lsn, target) >= 0) {
                 /*
@@ -553,7 +558,7 @@ xfs_ail_push(
          * the XFS_AIL_PUSHING_BIT.
          */
         smp_wmb();
-        ailp->xa_target = threshold_lsn;
+        xfs_trans_ail_copy_lsn(ailp, &ailp->xa_target, &threshold_lsn);
         if (!test_and_set_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags))
                 queue_delayed_work(xfs_syncd_wq, &ailp->xa_work, 0);
 }