Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: try to free metadata pages when we free btree blocks
  Btrfs: add extra flushing for renames and truncates
  Btrfs: make sure btrfs_update_delayed_ref doesn't increase ref_mod
  Btrfs: optimize fsyncs on old files
  Btrfs: tree logging unlink/rename fixes
  Btrfs: Make sure i_nlink doesn't hit zero too soon during log replay
  Btrfs: limit balancing work while flushing delayed refs
  Btrfs: readahead checksums during btrfs_finish_ordered_io
  Btrfs: leave btree locks spinning more often
  Btrfs: Only let very young transactions grow during commit
  Btrfs: Check for a blocking lock before taking the spin
  Btrfs: reduce stack in cow_file_range
  Btrfs: reduce stalls during transaction commit
  Btrfs: process the delayed reference queue in clusters
  Btrfs: try to cleanup delayed refs while freeing extents
  Btrfs: reduce stack usage in some crucial tree balancing functions
  Btrfs: do extent allocation and reference count updates in the background
  Btrfs: don't preallocate metadata blocks during btrfs_search_slot

1 files changed, 14 insertions, 7 deletions

diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 47b0a88..a5310c0 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -71,12 +71,13 @@ void btrfs_clear_lock_blocking(struct extent_buffer *eb)
 static int btrfs_spin_on_block(struct extent_buffer *eb)
 {
 	int i;
+
 	for (i = 0; i < 512; i++) {
-		cpu_relax();
 		if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
 			return 1;
 		if (need_resched())
 			break;
+		cpu_relax();
 	}
 	return 0;
 }
@@ -95,13 +96,15 @@ int btrfs_try_spin_lock(struct extent_buffer *eb)
 {
 	int i;
 
-	spin_nested(eb);
-	if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
-		return 1;
-	spin_unlock(&eb->lock);
-
+	if (btrfs_spin_on_block(eb)) {
+		spin_nested(eb);
+		if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags))
+			return 1;
+		spin_unlock(&eb->lock);
+	}
 	/* spin for a bit on the BLOCKING flag */
 	for (i = 0; i < 2; i++) {
+		cpu_relax();
 		if (!btrfs_spin_on_block(eb))
 			break;
 
@@ -148,6 +151,9 @@ int btrfs_tree_lock(struct extent_buffer *eb)
 	DEFINE_WAIT(wait);
 	wait.func = btrfs_wake_function;
 
+	if (!btrfs_spin_on_block(eb))
+		goto sleep;
+
 	while(1) {
 		spin_nested(eb);
 
@@ -165,9 +171,10 @@ int btrfs_tree_lock(struct extent_buffer *eb)
 		 * spin for a bit, and if the blocking flag goes away,
 		 * loop around
 		 */
+		cpu_relax();
 		if (btrfs_spin_on_block(eb))
 			continue;
-
+sleep:
 		prepare_to_wait_exclusive(&eb->lock_wq, &wait,
 					  TASK_UNINTERRUPTIBLE);