Btrfs: Write bio checksumming outside the FS mutex

This significantly improves streaming write performance by allowing
concurrency in the data checksumming.

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

1 files changed, 10 insertions, 1 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 457daf725d29..3e1f21c632c1 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -330,14 +330,23 @@ int __btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct btrfs_trans_handle *trans;
         int ret = 0;
+        char *sums = NULL;
+
+        ret = btrfs_csum_one_bio(root, bio, &sums);
+        BUG_ON(ret);
 
         mutex_lock(&root->fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 1);
+
         btrfs_set_trans_block_group(trans, inode);
-        btrfs_csum_file_blocks(trans, root, inode, bio);
+        btrfs_csum_file_blocks(trans, root, inode, bio, sums);
+
         ret = btrfs_end_transaction(trans, root);
         BUG_ON(ret);
         mutex_unlock(&root->fs_info->fs_mutex);
+
+        kfree(sums);
+
         return btrfs_map_bio(root, rw, bio, mirror_num);
 }