3 files changed, 124 insertions, 151 deletions

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index ee0e981aa9d1..67d5b2cddb98 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -816,75 +816,6 @@ xfs_setup_devices(
         return 0;
 }
 
-/*
- * XFS AIL push thread support
- */
-void
-xfsaild_wakeup(
-        struct xfs_ail          *ailp,
-        xfs_lsn_t               threshold_lsn)
-{
-        /* only ever move the target forwards */
-        if (XFS_LSN_CMP(threshold_lsn, ailp->xa_target) > 0) {
-                ailp->xa_target = threshold_lsn;
-                wake_up_process(ailp->xa_task);
-        }
-}
-
-STATIC int
-xfsaild(
-        void    *data)
-{
-        struct xfs_ail  *ailp = data;
-        xfs_lsn_t       last_pushed_lsn = 0;
-        long            tout = 0; /* milliseconds */
-
-        while (!kthread_should_stop()) {
-                /*
-                 * for short sleeps indicating congestion, don't allow us to
-                 * get woken early. Otherwise all we do is bang on the AIL lock
-                 * without making progress.
-                 */
-                if (tout && tout <= 20)
-                        __set_current_state(TASK_KILLABLE);
-                else
-                        __set_current_state(TASK_INTERRUPTIBLE);
-                schedule_timeout(tout ?
-                                 msecs_to_jiffies(tout) : MAX_SCHEDULE_TIMEOUT);
-
-                /* swsusp */
-                try_to_freeze();
-
-                ASSERT(ailp->xa_mount->m_log);
-                if (XFS_FORCED_SHUTDOWN(ailp->xa_mount))
-                        continue;
-
-                tout = xfsaild_push(ailp, &last_pushed_lsn);
-        }
-
-        return 0;
-}       /* xfsaild */
-
-int
-xfsaild_start(
-        struct xfs_ail  *ailp)
-{
-        ailp->xa_target = 0;
-        ailp->xa_task = kthread_run(xfsaild, ailp, "xfsaild/%s",
-                                    ailp->xa_mount->m_fsname);
-        if (IS_ERR(ailp->xa_task))
-                return -PTR_ERR(ailp->xa_task);
-        return 0;
-}
-
-void
-xfsaild_stop(
-        struct xfs_ail  *ailp)
-{
-        kthread_stop(ailp->xa_task);
-}
-
-
 /* Catch misguided souls that try to use this interface on XFS */
 STATIC struct inode *
 xfs_fs_alloc_inode(
@@ -1786,6 +1717,38 @@ xfs_destroy_zones(void)
 }
 
 STATIC int __init
+xfs_init_workqueues(void)
+{
+        /*
+         * max_active is set to 8 to give enough concurency to allow
+         * multiple work operations on each CPU to run. This allows multiple
+         * filesystems to be running sync work concurrently, and scales with
+         * the number of CPUs in the system.
+         */
+        xfs_syncd_wq = alloc_workqueue("xfssyncd", WQ_CPU_INTENSIVE, 8);
+        if (!xfs_syncd_wq)
+                goto out;
+
+        xfs_ail_wq = alloc_workqueue("xfsail", WQ_CPU_INTENSIVE, 8);
+        if (!xfs_ail_wq)
+                goto out_destroy_syncd;
+
+        return 0;
+
+out_destroy_syncd:
+        destroy_workqueue(xfs_syncd_wq);
+out:
+        return -ENOMEM;
+}
+
+STATIC void __exit
+xfs_destroy_workqueues(void)
+{
+        destroy_workqueue(xfs_ail_wq);
+        destroy_workqueue(xfs_syncd_wq);
+}
+
+STATIC int __init
 init_xfs_fs(void)
 {
         int                     error;
@@ -1800,10 +1763,14 @@ init_xfs_fs(void)
         if (error)
                 goto out;
 
-        error = xfs_mru_cache_init();
+        error = xfs_init_workqueues();
         if (error)
                 goto out_destroy_zones;
 
+        error = xfs_mru_cache_init();
+        if (error)
+                goto out_destroy_wq;
+
         error = xfs_filestream_init();
         if (error)
                 goto out_mru_cache_uninit;
@@ -1820,27 +1787,17 @@ init_xfs_fs(void)
         if (error)
                 goto out_cleanup_procfs;
 
-        /*
-         * max_active is set to 8 to give enough concurency to allow
-         * multiple work operations on each CPU to run. This allows multiple
-         * filesystems to be running sync work concurrently, and scales with
-         * the number of CPUs in the system.
-         */
-        xfs_syncd_wq = alloc_workqueue("xfssyncd", WQ_CPU_INTENSIVE, 8);
-        if (!xfs_syncd_wq) {
-                error = -ENOMEM;
+        error = xfs_init_workqueues();
+        if (error)
                 goto out_sysctl_unregister;
-        }
 
         vfs_initquota();
 
         error = register_filesystem(&xfs_fs_type);
         if (error)
-                goto out_destroy_xfs_syncd;
+                goto out_sysctl_unregister;
         return 0;
 
- out_destroy_xfs_syncd:
-        destroy_workqueue(xfs_syncd_wq);
  out_sysctl_unregister:
         xfs_sysctl_unregister();
  out_cleanup_procfs:
@@ -1851,6 +1808,8 @@ init_xfs_fs(void)
         xfs_filestream_uninit();
  out_mru_cache_uninit:
         xfs_mru_cache_uninit();
+ out_destroy_wq:
+        xfs_destroy_workqueues();
  out_destroy_zones:
         xfs_destroy_zones();
  out:
@@ -1862,12 +1821,12 @@ exit_xfs_fs(void)
 {
         vfs_exitquota();
         unregister_filesystem(&xfs_fs_type);
-        destroy_workqueue(xfs_syncd_wq);
         xfs_sysctl_unregister();
         xfs_cleanup_procfs();
         xfs_buf_terminate();
         xfs_filestream_uninit();
         xfs_mru_cache_uninit();
+        xfs_destroy_workqueues();
         xfs_destroy_zones();
 }
 
diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index 12aff9584e29..cb3aeac929bc 100644
--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -28,6 +28,8 @@
 #include "xfs_trans_priv.h"
 #include "xfs_error.h"
 
+struct workqueue_struct *xfs_ail_wq;    /* AIL workqueue */
+
 STATIC void xfs_ail_splice(struct xfs_ail *, struct list_head *, xfs_lsn_t);
 STATIC void xfs_ail_delete(struct xfs_ail *, xfs_log_item_t *);
 STATIC xfs_log_item_t * xfs_ail_min(struct xfs_ail *);
@@ -69,36 +71,6 @@ xfs_trans_ail_tail(
 }
 
 /*
- * xfs_trans_push_ail
- *
- * This routine is called to move the tail of the AIL forward.  It does this by
- * trying to flush items in the AIL whose lsns are below the given
- * threshold_lsn.
- *
- * the push is run asynchronously in a separate thread, so we return the tail
- * of the log right now instead of the tail after the push. This means we will
- * either continue right away, or we will sleep waiting on the async thread to
- * do its work.
- *
- * We do this unlocked - we only need to know whether there is anything in the
- * AIL at the time we are called. We don't need to access the contents of
- * any of the objects, so the lock is not needed.
- */
-void
-xfs_trans_ail_push(
-        struct xfs_ail  *ailp,
-        xfs_lsn_t       threshold_lsn)
-{
-        xfs_log_item_t  *lip;
-
-        lip = xfs_ail_min(ailp);
-        if (lip && !XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
-                if (XFS_LSN_CMP(threshold_lsn, ailp->xa_target) > 0)
-                        xfsaild_wakeup(ailp, threshold_lsn);
-        }
-}
-
-/*
  * AIL traversal cursor initialisation.
  *
  * The cursor keeps track of where our current traversal is up
@@ -236,16 +208,16 @@ out:
 }
 
 /*
- * xfsaild_push does the work of pushing on the AIL.  Returning a timeout of
- * zero indicates that the caller should sleep until woken.
+ * xfs_ail_worker does the work of pushing on the AIL. It will requeue itself
+ * to run at a later time if there is more work to do to complete the push.
  */
-long
-xfsaild_push(
-        struct xfs_ail  *ailp,
-        xfs_lsn_t       *last_lsn)
+STATIC void
+xfs_ail_worker(
+        struct work_struct *work)
 {
-        long            tout = 0;
-        xfs_lsn_t       last_pushed_lsn = *last_lsn;
+        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;
@@ -256,15 +228,15 @@ xfsaild_push(
 
         spin_lock(&ailp->xa_lock);
         xfs_trans_ail_cursor_init(ailp, cur);
-        lip = xfs_trans_ail_cursor_first(ailp, cur, *last_lsn);
+        lip = xfs_trans_ail_cursor_first(ailp, cur, ailp->xa_last_pushed_lsn);
         if (!lip || XFS_FORCED_SHUTDOWN(mp)) {
                 /*
                  * AIL is empty or our push has reached the end.
                  */
                 xfs_trans_ail_cursor_done(ailp, cur);
                 spin_unlock(&ailp->xa_lock);
-                *last_lsn = 0;
-                return tout;
+                ailp->xa_last_pushed_lsn = 0;
+                return;
         }
 
         XFS_STATS_INC(xs_push_ail);
@@ -301,13 +273,13 @@ xfsaild_push(
                 case XFS_ITEM_SUCCESS:
                         XFS_STATS_INC(xs_push_ail_success);
                         IOP_PUSH(lip);
-                        last_pushed_lsn = lsn;
+                        ailp->xa_last_pushed_lsn = lsn;
                         break;
 
                 case XFS_ITEM_PUSHBUF:
                         XFS_STATS_INC(xs_push_ail_pushbuf);
                         IOP_PUSHBUF(lip);
-                        last_pushed_lsn = lsn;
+                        ailp->xa_last_pushed_lsn = lsn;
                         push_xfsbufd = 1;
                         break;
 
@@ -319,7 +291,7 @@ xfsaild_push(
 
                 case XFS_ITEM_LOCKED:
                         XFS_STATS_INC(xs_push_ail_locked);
-                        last_pushed_lsn = lsn;
+                        ailp->xa_last_pushed_lsn = lsn;
                         stuck++;
                         break;
 
@@ -374,9 +346,23 @@ xfsaild_push(
                 wake_up_process(mp->m_ddev_targp->bt_task);
         }
 
+        /* assume we have more work to do in a short while */
+        tout = 10;
         if (!count) {
                 /* We're past our target or empty, so idle */
-                last_pushed_lsn = 0;
+                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.
+                 */
+                smp_rmb();
+                if (ailp->xa_target == target) {
+                        clear_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags);
+                        return;
+                }
+                tout = 50;
         } else if (XFS_LSN_CMP(lsn, target) >= 0) {
                 /*
                  * We reached the target so wait a bit longer for I/O to
@@ -384,7 +370,7 @@ xfsaild_push(
                  * start the next scan from the start of the AIL.
                  */
                 tout = 50;
-                last_pushed_lsn = 0;
+                ailp->xa_last_pushed_lsn = 0;
         } else if ((stuck * 100) / count > 90) {
                 /*
                  * Either there is a lot of contention on the AIL or we
@@ -396,14 +382,48 @@ xfsaild_push(
                  * continuing from where we were.
                  */
                 tout = 20;
-        } else {
-                /* more to do, but wait a short while before continuing */
-                tout = 10;
         }
-        *last_lsn = last_pushed_lsn;
-        return tout;
+
+        /* There is more to do, requeue us.  */
+        queue_delayed_work(xfs_syncd_wq, &ailp->xa_work,
+                                        msecs_to_jiffies(tout));
 }
 
+/*
+ * This routine is called to move the tail of the AIL forward.  It does this by
+ * trying to flush items in the AIL whose lsns are below the given
+ * threshold_lsn.
+ *
+ * The push is run asynchronously in a workqueue, which means the caller needs
+ * to handle waiting on the async flush for space to become available.
+ * We don't want to interrupt any push that is in progress, hence we only queue
+ * work if we set the pushing bit approriately.
+ *
+ * We do this unlocked - we only need to know whether there is anything in the
+ * AIL at the time we are called. We don't need to access the contents of
+ * any of the objects, so the lock is not needed.
+ */
+void
+xfs_trans_ail_push(
+        struct xfs_ail  *ailp,
+        xfs_lsn_t       threshold_lsn)
+{
+        xfs_log_item_t  *lip;
+
+        lip = xfs_ail_min(ailp);
+        if (!lip || XFS_FORCED_SHUTDOWN(ailp->xa_mount) ||
+            XFS_LSN_CMP(threshold_lsn, ailp->xa_target) <= 0)
+                return;
+
+        /*
+         * Ensure that the new target is noticed in push code before it clears
+         * the XFS_AIL_PUSHING_BIT.
+         */
+        smp_wmb();
+        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);
+}
 
 /*
  * This is to be called when an item is unlocked that may have
@@ -615,7 +635,6 @@ xfs_trans_ail_init(
         xfs_mount_t     *mp)
 {
         struct xfs_ail  *ailp;
-        int             error;
 
         ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL);
         if (!ailp)
@@ -624,15 +643,9 @@ xfs_trans_ail_init(
         ailp->xa_mount = mp;
         INIT_LIST_HEAD(&ailp->xa_ail);
         spin_lock_init(&ailp->xa_lock);
-        error = xfsaild_start(ailp);
-        if (error)
-                goto out_free_ailp;
+        INIT_DELAYED_WORK(&ailp->xa_work, xfs_ail_worker);
         mp->m_ail = ailp;
         return 0;
-
-out_free_ailp:
-        kmem_free(ailp);
-        return error;
 }
 
 void
@@ -641,7 +654,7 @@ xfs_trans_ail_destroy(
 {
         struct xfs_ail  *ailp = mp->m_ail;
 
-        xfsaild_stop(ailp);
+        cancel_delayed_work_sync(&ailp->xa_work);
         kmem_free(ailp);
 }
 
diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h
index 35162c238fa3..6ebd322bd37c 100644
--- a/fs/xfs/xfs_trans_priv.h
+++ b/fs/xfs/xfs_trans_priv.h
@@ -65,16 +65,22 @@ struct xfs_ail_cursor {
 struct xfs_ail {
         struct xfs_mount        *xa_mount;
         struct list_head        xa_ail;
-        uint                    xa_gen;
-        struct task_struct      *xa_task;
         xfs_lsn_t               xa_target;
         struct xfs_ail_cursor   xa_cursors;
         spinlock_t              xa_lock;
+        struct delayed_work     xa_work;
+        xfs_lsn_t               xa_last_pushed_lsn;
+        unsigned long           xa_flags;
 };
 
+#define XFS_AIL_PUSHING_BIT     0
+
 /*
  * From xfs_trans_ail.c
  */
+
+extern struct workqueue_struct  *xfs_ail_wq;    /* AIL workqueue */
+
 void    xfs_trans_ail_update_bulk(struct xfs_ail *ailp,
                                 struct xfs_log_item **log_items, int nr_items,
                                 xfs_lsn_t lsn) __releases(ailp->xa_lock);
@@ -112,11 +118,6 @@ struct xfs_log_item	*xfs_trans_ail_cursor_next(struct xfs_ail *ailp,
 void                    xfs_trans_ail_cursor_done(struct xfs_ail *ailp,
                                         struct xfs_ail_cursor *cur);
 
-long    xfsaild_push(struct xfs_ail *, xfs_lsn_t *);
-void    xfsaild_wakeup(struct xfs_ail *, xfs_lsn_t);
-int     xfsaild_start(struct xfs_ail *);
-void    xfsaild_stop(struct xfs_ail *);
-
 #if BITS_PER_LONG != 64
 static inline void
 xfs_trans_ail_copy_lsn(