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// SPDX-License-Identifier: GPL-2.0-or-later
/* Single, monolithic object support (e.g. AFS directory).
*
* Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/uio.h>
#include <linux/sched/mm.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/netfs.h>
#include "internal.h"
/**
* netfs_single_mark_inode_dirty - Mark a single, monolithic object inode dirty
* @inode: The inode to mark
*
* Mark an inode that contains a single, monolithic object as dirty so that its
* writepages op will get called. If set, the SINGLE_NO_UPLOAD flag indicates
* that the object will only be written to the cache and not uploaded (e.g. AFS
* directory contents).
*/
void netfs_single_mark_inode_dirty(struct inode *inode)
{
struct netfs_inode *ictx = netfs_inode(inode);
bool cache_only = test_bit(NETFS_ICTX_SINGLE_NO_UPLOAD, &ictx->flags);
bool caching = fscache_cookie_enabled(netfs_i_cookie(netfs_inode(inode)));
if (cache_only && !caching)
return;
mark_inode_dirty(inode);
if (caching && !(inode->i_state & I_PINNING_NETFS_WB)) {
bool need_use = false;
spin_lock(&inode->i_lock);
if (!(inode->i_state & I_PINNING_NETFS_WB)) {
inode->i_state |= I_PINNING_NETFS_WB;
need_use = true;
}
spin_unlock(&inode->i_lock);
if (need_use)
fscache_use_cookie(netfs_i_cookie(ictx), true);
}
}
EXPORT_SYMBOL(netfs_single_mark_inode_dirty);
static int netfs_single_begin_cache_read(struct netfs_io_request *rreq, struct netfs_inode *ctx)
{
return fscache_begin_read_operation(&rreq->cache_resources, netfs_i_cookie(ctx));
}
static void netfs_single_cache_prepare_read(struct netfs_io_request *rreq,
struct netfs_io_subrequest *subreq)
{
struct netfs_cache_resources *cres = &rreq->cache_resources;
if (!cres->ops) {
subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
return;
}
subreq->source = cres->ops->prepare_read(subreq, rreq->i_size);
trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
}
static void netfs_single_read_cache(struct netfs_io_request *rreq,
struct netfs_io_subrequest *subreq)
{
struct netfs_cache_resources *cres = &rreq->cache_resources;
_enter("R=%08x[%x]", rreq->debug_id, subreq->debug_index);
netfs_stat(&netfs_n_rh_read);
cres->ops->read(cres, subreq->start, &subreq->io_iter, NETFS_READ_HOLE_FAIL,
netfs_cache_read_terminated, subreq);
}
/*
* Perform a read to a buffer from the cache or the server. Only a single
* subreq is permitted as the object must be fetched in a single transaction.
*/
static int netfs_single_dispatch_read(struct netfs_io_request *rreq)
{
struct netfs_io_stream *stream = &rreq->io_streams[0];
struct netfs_io_subrequest *subreq;
int ret = 0;
subreq = netfs_alloc_subrequest(rreq);
if (!subreq)
return -ENOMEM;
subreq->source = NETFS_SOURCE_UNKNOWN;
subreq->start = 0;
subreq->len = rreq->len;
subreq->io_iter = rreq->buffer.iter;
__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
spin_lock(&rreq->lock);
list_add_tail(&subreq->rreq_link, &stream->subrequests);
trace_netfs_sreq(subreq, netfs_sreq_trace_added);
stream->front = subreq;
/* Store list pointers before active flag */
smp_store_release(&stream->active, true);
spin_unlock(&rreq->lock);
netfs_single_cache_prepare_read(rreq, subreq);
switch (subreq->source) {
case NETFS_DOWNLOAD_FROM_SERVER:
netfs_stat(&netfs_n_rh_download);
if (rreq->netfs_ops->prepare_read) {
ret = rreq->netfs_ops->prepare_read(subreq);
if (ret < 0)
goto cancel;
}
rreq->netfs_ops->issue_read(subreq);
rreq->submitted += subreq->len;
break;
case NETFS_READ_FROM_CACHE:
trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
netfs_single_read_cache(rreq, subreq);
rreq->submitted += subreq->len;
ret = 0;
break;
default:
pr_warn("Unexpected single-read source %u\n", subreq->source);
WARN_ON_ONCE(true);
ret = -EIO;
break;
}
smp_wmb(); /* Write lists before ALL_QUEUED. */
set_bit(NETFS_RREQ_ALL_QUEUED, &rreq->flags);
return ret;
cancel:
netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_cancel);
return ret;
}
/**
* netfs_read_single - Synchronously read a single blob of pages.
* @inode: The inode to read from.
* @file: The file we're using to read or NULL.
* @iter: The buffer we're reading into.
*
* Fulfil a read request for a single monolithic object by drawing data from
* the cache if possible, or the netfs if not. The buffer may be larger than
* the file content; unused beyond the EOF will be zero-filled. The content
* will be read with a single I/O request (though this may be retried).
*
* The calling netfs must initialise a netfs context contiguous to the vfs
* inode before calling this.
*
* This is usable whether or not caching is enabled. If caching is enabled,
* the data will be stored as a single object into the cache.
*/
ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter)
{
struct netfs_io_request *rreq;
struct netfs_inode *ictx = netfs_inode(inode);
ssize_t ret;
rreq = netfs_alloc_request(inode->i_mapping, file, 0, iov_iter_count(iter),
NETFS_READ_SINGLE);
if (IS_ERR(rreq))
return PTR_ERR(rreq);
ret = netfs_single_begin_cache_read(rreq, ictx);
if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
goto cleanup_free;
netfs_stat(&netfs_n_rh_read_single);
trace_netfs_read(rreq, 0, rreq->len, netfs_read_trace_read_single);
rreq->buffer.iter = *iter;
netfs_single_dispatch_read(rreq);
ret = netfs_wait_for_read(rreq);
netfs_put_request(rreq, true, netfs_rreq_trace_put_return);
return ret;
cleanup_free:
netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
return ret;
}
EXPORT_SYMBOL(netfs_read_single);
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