Re: [PATCH 31/35] nfs: dont change wbc->nr_to_write in write_inode()

Trond Myklebust
2010-12-13T21:01:49Z

On Mon, 2010-12-13 at 22:47 +0800, Wu Fengguang wrote:
> plain text document attachment
> (writeback-nfs-commit-remove-nr_to_write.patch)
> It's introduced in commit 420e3646 ("NFS: Reduce the number of
> unnecessary COMMIT calls") and seems not necessary.
>
> CC: Trond Myklebust <Trond.Myklebust@netapp.com>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
> ---
> fs/nfs/write.c | 9 +--------
> 1 file changed, 1 insertion(+), 8 deletions(-)
>
> --- linux-next.orig/fs/nfs/write.c 2010-12-13 21:46:21.000000000 +0800
> +++ linux-next/fs/nfs/write.c 2010-12-13 21:46:22.000000000 +0800
> @@ -1557,15 +1557,8 @@ static int nfs_commit_unstable_pages(str
> }
>
> ret = nfs_commit_inode(inode, flags);
> - if (ret >= 0) {
> - if (wbc->sync_mode == WB_SYNC_NONE) {
> - if (ret < wbc->nr_to_write)
> - wbc->nr_to_write -= ret;
> - else
> - wbc->nr_to_write = 0;
> - }
> + if (ret >= 0)
> return 0;
> - }
> out_mark_dirty:
> __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
> return ret;

It is there in order to tell the VM that it has succeeded in freeing up
a certain number of pages. Otherwise, we end up cycling forever in
writeback_sb_inodes() & friends with the latter not realising that they
have made progress.

Cheers
Trond

--
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@netapp.com