On Sun, 3 Nov 2013 23:24:34 +0800, Liu Bo wrote:
> The 'git blame' history shows that, the old transaction commit code has to do
> twice to ensure roots are updated and we have to flush metadata and super
> block
> manually, however, right now all of these can be handled well inside
> the transaction commit code without extra efforts.
>
> And the error handling part remains same with the current code, -- 'return to
> caller once we get error'.
>
> This saves us a transaction commit and a flush of super block, which are both
> heavy operations according to ftrace output analysis.
>
> Signed-off-by: Liu Bo <bo.li....@oracle.com>
> ---
> fs/btrfs/disk-io.c | 20 +-------------------
> 1 file changed, 1 insertion(+), 19 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 62176ad..d6728c3 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -3542,25 +3542,7 @@ int btrfs_commit_super(struct btrfs_root *root)
> trans = btrfs_join_transaction(root);
> if (IS_ERR(trans))
> return PTR_ERR(trans);
> - ret = btrfs_commit_transaction(trans, root);
> - if (ret)
> - return ret;
> - /* run commit again to drop the original snapshot */
> - trans = btrfs_join_transaction(root);
> - if (IS_ERR(trans))
> - return PTR_ERR(trans);
> - ret = btrfs_commit_transaction(trans, root);
> - if (ret)
> - return ret;
> - ret = btrfs_write_and_wait_transaction(NULL, root);
> - if (ret) {
> - btrfs_error(root->fs_info, ret,
> - "Failed to sync btree inode to disk.");
> - return ret;
> - }
> -
> - ret = write_ctree_super(NULL, root, 0);
> - return ret;
> + return btrfs_commit_transaction(trans, root);
> }
>
> int close_ctree(struct btrfs_root *root)
>
fs/btrfs/disk-io.c: In function 'btrfs_commit_super':
fs/btrfs/disk-io.c:3520: warning: unused variable 'ret'
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