2 files changed, 31 insertions, 2 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index e72a013d24bf..202c1b6df4a4 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -20,6 +20,7 @@
 #include <linux/sched.h>
 #include <linux/writeback.h>
 #include <linux/pagemap.h>
+#include <linux/blkdev.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
@@ -331,6 +332,7 @@ int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
         int werr = 0;
         struct page *page;
         struct inode *btree_inode = root->fs_info->btree_inode;
+        struct extent_io_tree *io_tree = &BTRFS_I(btree_inode)->io_tree;
         u64 start = 0;
         u64 end;
         unsigned long index;
@@ -371,6 +373,11 @@ int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
                         page_cache_release(page);
                 }
         }
+        /*
+         * we unplug once and then use the wait_on_extent_bit for
+         * everything else
+         */
+        blk_run_address_space(btree_inode->i_mapping);
         while(1) {
                 ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
                                             EXTENT_DIRTY);
@@ -391,7 +398,28 @@ int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
                                 if (err)
                                         werr = err;
                         }
-                        wait_on_page_writeback(page);
+                        if (PageWriteback(page)) {
+                                /*
+                                 * we don't wait on the page writeback bit
+                                 * because that triggers a lot of unplugs.
+                                 * The extent bits are much nicer to
+                                 * the disks, but come with a slightly
+                                 * higher latency because we aren't forcing
+                                 * unplugs.
+                                 */
+                                wait_on_extent_writeback(io_tree,
+                                         page_offset(page),
+                                         page_offset(page) +
+                                         PAGE_CACHE_SIZE - 1);
+                        }
+                        if (PageWriteback(page)) {
+                                /*
+                                 * the state bits get cleared before the
+                                 * page bits, lets add some extra
+                                 * paranoia here
+                                 */
+                                wait_on_page_writeback(page);
+                        }
                         page_cache_release(page);
                         cond_resched();
                 }
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index cbb9bb31431d..80a27284dbf1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -200,7 +200,8 @@ loop:
                  * is now congested.  Back off and let other work structs
                  * run instead
                  */
-                if (pending && bdi_write_congested(bdi)) {
+                if (pending && bdi_write_congested(bdi) &&
+                    fs_info->fs_devices->open_devices > 1) {
                         struct bio *old_head;
 
                         spin_lock(&device->io_lock);