Btrfs: map the inode item when doing fill_inode_item

Instead of calling kmap_atomic for every thing we set in the inode item, map the
entire inode item at the start and unmap it at the end.  This makes a sequential
dd of 400mb O_DIRECT something like 1% faster.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index cc6022842e0c..da2680263d9f 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2589,6 +2589,13 @@ static void fill_inode_item(struct btrfs_trans_handle *trans,
                             struct btrfs_inode_item *item,
                             struct inode *inode)
 {
+        if (!leaf->map_token)
+                map_private_extent_buffer(leaf, (unsigned long)item,
+                                          sizeof(struct btrfs_inode_item),
+                                          &leaf->map_token, &leaf->kaddr,
+                                          &leaf->map_start, &leaf->map_len,
+                                          KM_USER1);
+
         btrfs_set_inode_uid(leaf, item, inode->i_uid);
         btrfs_set_inode_gid(leaf, item, inode->i_gid);
         btrfs_set_inode_size(leaf, item, BTRFS_I(inode)->disk_i_size);
@@ -2617,6 +2624,11 @@ static void fill_inode_item(struct btrfs_trans_handle *trans,
         btrfs_set_inode_rdev(leaf, item, inode->i_rdev);
         btrfs_set_inode_flags(leaf, item, BTRFS_I(inode)->flags);
         btrfs_set_inode_block_group(leaf, item, BTRFS_I(inode)->block_group);
+
+        if (leaf->map_token) {
+                unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
+                leaf->map_token = NULL;
+        }
 }
 
 /*