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

Pull xfs update from Ben Myers:
 "Numerous cleanups and several bug fixes.  Here are some highlights:

   - Discontiguous directory buffer support
   - Inode allocator refactoring
   - Removal of the IO lock in inode reclaim
   - Implementation of .update_time
   - Fix for handling of EOF in xfs_vm_writepage
   - Fix for races in xfsaild, and idle mode is re-enabled
   - Fix for a crash in xfs_buf completion handlers on unmount."

Fix up trivial conflicts in fs/xfs/{xfs_buf.c,xfs_log.c,xfs_log_priv.h}
due to duplicate patches that had already been merged for 3.5.

* tag 'for-linus-v3.6-rc1' of git://oss.sgi.com/xfs/xfs: (44 commits)
  xfs: wait for the write the superblock on unmount
  xfs: re-enable xfsaild idle mode and fix associated races
  xfs: remove iolock lock classes
  xfs: avoid the iolock in xfs_free_eofblocks for evicted inodes
  xfs: do not take the iolock in xfs_inactive
  xfs: remove xfs_inactive_attrs
  xfs: clean up xfs_inactive
  xfs: do not read the AGI buffer in xfs_dialloc until nessecary
  xfs: refactor xfs_ialloc_ag_select
  xfs: add a short cut to xfs_dialloc for the non-NULL agbp case
  xfs: remove the alloc_done argument to xfs_dialloc
  xfs: split xfs_dialloc
  xfs: remove xfs_ialloc_find_free
  Prefix IO_XX flags with XFS_IO_XX to avoid namespace colision.
  xfs: remove xfs_inotobp
  xfs: merge xfs_itobp into xfs_imap_to_bp
  xfs: handle EOF correctly in xfs_vm_writepage
  xfs: implement ->update_time
  xfs: fix comment typo of struct xfs_da_blkinfo.
  xfs: do not call xfs_bdstrat_cb in xfs_buf_iodone_callbacks
  ...

1 files changed, 32 insertions, 3 deletions

diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index 9c514483e599..6011ee661339 100644
--- 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();