Commit message: NFS: Allow nfs_updatepage to extend a write under additional circumstances

Currently nfs_updatepage allows a write to be extended to cover a full
page only if we don't have a byte range lock lock on the file... but if
we have a write delegation on the file or if we have the whole file
locked for writing then we should be allowed to extend the write as
well.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
[Trond: fix up call to nfs_have_delegation()]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
CVE: None
Vulnerability description: None

Project: linux
File: write.c

static void nfs_async_write_error(struct list_head *head)
{
	struct nfs_page	*req;

	while (!list_empty(head)) {
		req = nfs_list_entry(head->next);
		nfs_list_remove_request(req);
		nfs_redirty_request(req);
	}
}

Project: linux
File: write.c

int nfs_flush_incompatible(struct file *file, struct page *page)
{
	struct nfs_open_context *ctx = nfs_file_open_context(file);
	struct nfs_lock_context *l_ctx;
	struct nfs_page	*req;
	int do_flush, status;
	/*
	 * Look for a request corresponding to this page. If there
	 * is one, and it belongs to another file, we flush it out
	 * before we try to copy anything into the page. Do this
	 * due to the lack of an ACCESS-type call in NFSv2.
	 * Also do the same if we find a request from an existing
	 * dropped page.
	 */
	do {
		req = nfs_page_find_request(page);
		if (req == NULL)
			return 0;
		l_ctx = req->wb_lock_context;
		do_flush = req->wb_page != page || req->wb_context != ctx;
		if (l_ctx) {
			do_flush |= l_ctx->lockowner.l_owner != current->files
				|| l_ctx->lockowner.l_pid != current->tgid;
		}
		nfs_release_request(req);
		if (!do_flush)
			return 0;
		status = nfs_wb_page(page_file_mapping(page)->host, page);
	} while (status == 0);
	return status;
}

Project: linux
File: write.c

int nfs_updatepage(struct file *file, struct page *page,
		unsigned int offset, unsigned int count)
{
	struct nfs_open_context *ctx = nfs_file_open_context(file);
	struct inode	*inode = page_file_mapping(page)->host;
	int		status = 0;

	nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);

	dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
		file->f_path.dentry->d_parent->d_name.name,
		file->f_path.dentry->d_name.name, count,
		(long long)(page_file_offset(page) + offset));

	if (nfs_can_extend_write(file, page, inode)) {
		count = max(count + offset, nfs_page_length(page));
		offset = 0;
	}

	status = nfs_writepage_setup(ctx, page, offset, count);
	if (status < 0)
		nfs_set_pageerror(page);
	else
		__set_page_dirty_nobuffers(page);

	dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
			status, (long long)i_size_read(inode));
	return status;
}

Project: linux
File: write.c

int nfs_wb_page(struct inode *inode, struct page *page)
{
	loff_t range_start = page_file_offset(page);
	loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
	struct writeback_control wbc = {
		.sync_mode = WB_SYNC_ALL,
		.nr_to_write = 0,
		.range_start = range_start,
		.range_end = range_end,
	};
	int ret;

	for (;;) {
		wait_on_page_writeback(page);
		if (clear_page_dirty_for_io(page)) {
			ret = nfs_writepage_locked(page, &wbc);
			if (ret < 0)
				goto out_error;
			continue;
		}
		if (!PagePrivate(page))
			break;
		ret = nfs_commit_inode(inode, FLUSH_SYNC);
		if (ret < 0)
			goto out_error;
	}
	return 0;
out_error:
	return ret;
}

Project: linux
File: write.c

int nfs_write_need_commit(struct nfs_write_data *data)
{
	if (data->verf.committed == NFS_DATA_SYNC)
		return data->header->lseg == NULL;
	return data->verf.committed != NFS_FILE_SYNC;
}

Project: linux
File: write.c

int nfs_initiate_write(struct rpc_clnt *clnt,
		       struct nfs_write_data *data,
		       const struct rpc_call_ops *call_ops,
		       int how, int flags)
{
	struct inode *inode = data->header->inode;
	int priority = flush_task_priority(how);
	struct rpc_task *task;
	struct rpc_message msg = {
		.rpc_argp = &data->args,
		.rpc_resp = &data->res,
		.rpc_cred = data->header->cred,
	};
	struct rpc_task_setup task_setup_data = {
		.rpc_client = clnt,
		.task = &data->task,
		.rpc_message = &msg,
		.callback_ops = call_ops,
		.callback_data = data,
		.workqueue = nfsiod_workqueue,
		.flags = RPC_TASK_ASYNC | flags,
		.priority = priority,
	};
	int ret = 0;

	/* Set up the initial task struct.  */
	NFS_PROTO(inode)->write_setup(data, &msg);

	dprintk("NFS: %5u initiated write call "
		"(req %s/%lld, %u bytes @ offset %llu)\n",
		data->task.tk_pid,
		inode->i_sb->s_id,
		(long long)NFS_FILEID(inode),
		data->args.count,
		(unsigned long long)data->args.offset);

	task = rpc_run_task(&task_setup_data);
	if (IS_ERR(task)) {
		ret = PTR_ERR(task);
		goto out;
	}
	if (how & FLUSH_SYNC) {
		ret = rpc_wait_for_completion_task(task);
		if (ret == 0)
			ret = task->tk_status;
	}
	rpc_put_task(task);
out:
	return ret;
}

Project: linux
File: write.c

int nfs_wb_all(struct inode *inode)
{
	struct writeback_control wbc = {
		.sync_mode = WB_SYNC_ALL,
		.nr_to_write = LONG_MAX,
		.range_start = 0,
		.range_end = LLONG_MAX,
	};

	return sync_inode(inode, &wbc);
}

Project: linux
File: write.c

int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
			const struct rpc_call_ops *call_ops,
			int how, int flags)
{
	struct rpc_task *task;
	int priority = flush_task_priority(how);
	struct rpc_message msg = {
		.rpc_argp = &data->args,
		.rpc_resp = &data->res,
		.rpc_cred = data->cred,
	};
	struct rpc_task_setup task_setup_data = {
		.task = &data->task,
		.rpc_client = clnt,
		.rpc_message = &msg,
		.callback_ops = call_ops,
		.callback_data = data,
		.workqueue = nfsiod_workqueue,
		.flags = RPC_TASK_ASYNC | flags,
		.priority = priority,
	};
	/* Set up the initial task struct.  */
	NFS_PROTO(data->inode)->commit_setup(data, &msg);

	dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);

	task = rpc_run_task(&task_setup_data);
	if (IS_ERR(task))
		return PTR_ERR(task);
	if (how & FLUSH_SYNC)
		rpc_wait_for_completion_task(task);
	rpc_put_task(task);
	return 0;
}

Project: linux
File: write.c

void nfs_write_prepare(struct rpc_task *task, void *calldata)
{
	struct nfs_write_data *data = calldata;
	NFS_PROTO(data->header->inode)->write_rpc_prepare(task, data);
	if (unlikely(test_bit(NFS_CONTEXT_BAD, &data->args.context->flags)))
		rpc_exit(task, -EIO);
}

Project: linux
File: write.c

static void nfs_commit_release_pages(struct nfs_commit_data *data)
{
	struct nfs_page	*req;
	int status = data->task.tk_status;
	struct nfs_commit_info cinfo;

	while (!list_empty(&data->pages)) {
		req = nfs_list_entry(data->pages.next);
		nfs_list_remove_request(req);
		nfs_clear_page_commit(req->wb_page);

		dprintk("NFS:       commit (%s/%lld %d@%lld)",
			req->wb_context->dentry->d_sb->s_id,
			(long long)NFS_FILEID(req->wb_context->dentry->d_inode),
			req->wb_bytes,
			(long long)req_offset(req));
		if (status < 0) {
			nfs_context_set_write_error(req->wb_context, status);
			nfs_inode_remove_request(req);
			dprintk(", error = %d\n", status);
			goto next;
		}

		/* Okay, COMMIT succeeded, apparently. Check the verifier
		 * returned by the server against all stored verfs. */
		if (!memcmp(&req->wb_verf, &data->verf.verifier, sizeof(req->wb_verf))) {
			/* We have a match */
			nfs_inode_remove_request(req);
			dprintk(" OK\n");
			goto next;
		}
		/* We have a mismatch. Write the page again */
		dprintk(" mismatch\n");
		nfs_mark_request_dirty(req);
		set_bit(NFS_CONTEXT_RESEND_WRITES, &req->wb_context->flags);
	next:
		nfs_unlock_and_release_request(req);
	}
	nfs_init_cinfo(&cinfo, data->inode, data->dreq);
	if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
		nfs_commit_clear_lock(NFS_I(data->inode));
}