linux/fs/netfs/read_collect.c

// SPDX-License-Identifier: GPL-2.0-only
/* Network filesystem read subrequest result collection, assessment and
 * retrying.
 *
 * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 */

#include <linux/export.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/task_io_accounting_ops.h>
#include "internal.h"

/*
 * Clear the unread part of an I/O request.
 */
static void netfs_clear_unread(struct netfs_io_subrequest *subreq)
{ … }

/*
 * Flush, mark and unlock a folio that's now completely read.  If we want to
 * cache the folio, we set the group to NETFS_FOLIO_COPY_TO_CACHE, mark it
 * dirty and let writeback handle it.
 */
static void netfs_unlock_read_folio(struct netfs_io_subrequest *subreq,
				    struct netfs_io_request *rreq,
				    struct folio_queue *folioq,
				    int slot)
{ … }

/*
 * Unlock any folios that are now completely read.  Returns true if the
 * subrequest is removed from the list.
 */
static bool netfs_consume_read_data(struct netfs_io_subrequest *subreq, bool was_async)
{ … }

/*
 * Do page flushing and suchlike after DIO.
 */
static void netfs_rreq_assess_dio(struct netfs_io_request *rreq)
{ … }

/*
 * Assess the state of a read request and decide what to do next.
 *
 * Note that we're in normal kernel thread context at this point, possibly
 * running on a workqueue.
 */
static void netfs_rreq_assess(struct netfs_io_request *rreq)
{ … }

void netfs_read_termination_worker(struct work_struct *work)
{ … }

/*
 * Handle the completion of all outstanding I/O operations on a read request.
 * We inherit a ref from the caller.
 */
void netfs_rreq_terminated(struct netfs_io_request *rreq, bool was_async)
{ … }

/**
 * netfs_read_subreq_progress - Note progress of a read operation.
 * @subreq: The read request that has terminated.
 * @was_async: True if we're in an asynchronous context.
 *
 * This tells the read side of netfs lib that a contributory I/O operation has
 * made some progress and that it may be possible to unlock some folios.
 *
 * Before calling, the filesystem should update subreq->transferred to track
 * the amount of data copied into the output buffer.
 *
 * If @was_async is true, the caller might be running in softirq or interrupt
 * context and we can't sleep.
 */
void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq,
				bool was_async)
{ … }
EXPORT_SYMBOL(…);

/**
 * netfs_read_subreq_terminated - Note the termination of an I/O operation.
 * @subreq: The I/O request that has terminated.
 * @error: Error code indicating type of completion.
 * @was_async: The termination was asynchronous
 *
 * This tells the read helper that a contributory I/O operation has terminated,
 * one way or another, and that it should integrate the results.
 *
 * The caller indicates the outcome of the operation through @error, supplying
 * 0 to indicate a successful or retryable transfer (if NETFS_SREQ_NEED_RETRY
 * is set) or a negative error code.  The helper will look after reissuing I/O
 * operations as appropriate and writing downloaded data to the cache.
 *
 * Before calling, the filesystem should update subreq->transferred to track
 * the amount of data copied into the output buffer.
 *
 * If @was_async is true, the caller might be running in softirq or interrupt
 * context and we can't sleep.
 */
void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq,
				  int error, bool was_async)
{ … }
EXPORT_SYMBOL(…);