Btrfs: switch back to wait_on_page_writeback to wait on metadata writes

The extent based waiting was using more CPU, and other fixes have helped
with the unplug storm problems.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 1 insertions, 28 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index e9c8ebeedd7e..c2c3b4281962 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -332,7 +332,6 @@ 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;
@@ -373,11 +372,6 @@ 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);
@@ -398,28 +392,7 @@ int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
                                 if (err)
                                         werr = err;
                         }
-                        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);
-                        }
+                        wait_on_page_writeback(page);
                         page_cache_release(page);
                         cond_resched();
                 }