Btrfs: Create a work queue for bio writes

This allows checksumming to happen in parallel among many cpus, and
keeps us from bogging down pdflush with the checksumming code.

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

1 files changed, 20 insertions, 8 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 7869c0157a1f..457daf725d29 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -324,13 +324,29 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
         return 0;
 }
 
-int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
+int __btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
                           int mirror_num)
 {
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct btrfs_trans_handle *trans;
         int ret = 0;
 
+        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);
+        ret = btrfs_end_transaction(trans, root);
+        BUG_ON(ret);
+        mutex_unlock(&root->fs_info->fs_mutex);
+        return btrfs_map_bio(root, rw, bio, mirror_num);
+}
+
+int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
+                          int mirror_num)
+{
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        int ret = 0;
+
         if (!(rw & (1 << BIO_RW))) {
                 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
                 BUG_ON(ret);
@@ -342,13 +358,9 @@ int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
                 goto mapit;
         }
 
-        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);
-        ret = btrfs_end_transaction(trans, root);
-        BUG_ON(ret);
-        mutex_unlock(&root->fs_info->fs_mutex);
+        return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info,
+                                   inode, rw, bio, mirror_num,
+                                   __btrfs_submit_bio_hook);
 mapit:
         return btrfs_map_bio(root, rw, bio, mirror_num);
 }