NFS: Remove call to igrab() from nfs_writepage()

	struct nfs_open_context *ctx;

	struct inode *inode = page->mapping->host;

	unsigned offset;

	int inode_referenced = 0;

	int priority = wb_priority(wbc);

	int err;

	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);

	nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);

	/*

	 * Note: We need to ensure that we have a reference to the inode

	 *       if we are to do asynchronous writes. If not, waiting

	 *       in nfs_wait_on_request() may deadlock with clear_inode().

	 *

	 *       If igrab() fails here, then it is in any case safe to

	 *       call nfs_wb_page(), since there will be no pending writes.

	 */

	if (igrab(inode) != 0)

		inode_referenced = 1;

	/* Ensure we've flushed out any previous writes */

	nfs_wb_page_priority(inode, page, priority);

		goto out;

	}

	lock_kernel();

	if (!IS_SYNC(inode) && inode_referenced) {

	if (!IS_SYNC(inode)) {

		err = nfs_writepage_async(ctx, inode, page, 0, offset);

		if (!wbc->for_writepages)

			nfs_flush_mapping(page->mapping, wbc, wb_priority(wbc));

	put_nfs_open_context(ctx);

out:

	unlock_page(page);

	if (inode_referenced)

		iput(inode);

	return err; 

}