Commit ab0a3dbe authored by Trond Myklebust's avatar Trond Myklebust
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[PATCH] NFS: Write optimization for short files and small O_SYNC writes. 



 Use stable writes if we can see that we are only going to put a single
 write on the wire.

 Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent fe51beec

fs/nfs/write.c

+11 −3
Original line number Diff line number Diff line
@@ -750,7 +750,7 @@ int nfs_updatepage(struct file *file, struct page *page, 
	 * is entirely in cache, it may be more efficient to avoid

	 * fragmenting write requests.

	 */

	if (PageUptodate(page) && inode->i_flock == NULL) {

	if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {

		loff_t end_offs = i_size_read(inode) - 1;

		unsigned long end_index = end_offs >> PAGE_CACHE_SHIFT;
@@ -1342,8 +1342,16 @@ static int nfs_flush_inode(struct inode *inode, unsigned long idx_start, 
	spin_lock(&nfsi->req_lock);

	res = nfs_scan_dirty(inode, &head, idx_start, npages);

	spin_unlock(&nfsi->req_lock);

	if (res)

		error = nfs_flush_list(&head, NFS_SERVER(inode)->wpages, how);

	if (res) {

		struct nfs_server *server = NFS_SERVER(inode);



		/* For single writes, FLUSH_STABLE is more efficient */

		if (res == nfsi->npages && nfsi->npages <= server->wpages) {

			if (res > 1 || nfs_list_entry(head.next)->wb_bytes <= server->wsize)

				how |= FLUSH_STABLE;

		}

		error = nfs_flush_list(&head, server->wpages, how);

	}

	if (error < 0)

		return error;

	return res;