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// SPDX-License-Identifier: GPL-2.0-only
/* Network filesystem write retrying.
*
* Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include "internal.h"
/*
* Perform retries on the streams that need it.
*/
static void netfs_retry_write_stream(struct netfs_io_request *wreq,
struct netfs_io_stream *stream)
{
struct list_head *next;
_enter("R=%x[%x:]", wreq->debug_id, stream->stream_nr);
if (list_empty(&stream->subrequests))
return;
if (stream->source == NETFS_UPLOAD_TO_SERVER &&
wreq->netfs_ops->retry_request)
wreq->netfs_ops->retry_request(wreq, stream);
if (unlikely(stream->failed))
return;
/* If there's no renegotiation to do, just resend each failed subreq. */
if (!stream->prepare_write) {
struct netfs_io_subrequest *subreq;
list_for_each_entry(subreq, &stream->subrequests, rreq_link) {
if (test_bit(NETFS_SREQ_FAILED, &subreq->flags))
break;
if (__test_and_clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) {
struct iov_iter source = subreq->io_iter;
iov_iter_revert(&source, subreq->len - source.count);
netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
netfs_reissue_write(stream, subreq, &source);
}
}
return;
}
next = stream->subrequests.next;
do {
struct netfs_io_subrequest *subreq = NULL, *from, *to, *tmp;
struct iov_iter source;
unsigned long long start, len;
size_t part;
bool boundary = false;
/* Go through the stream and find the next span of contiguous
* data that we then rejig (cifs, for example, needs the wsize
* renegotiating) and reissue.
*/
from = list_entry(next, struct netfs_io_subrequest, rreq_link);
to = from;
start = from->start + from->transferred;
len = from->len - from->transferred;
if (test_bit(NETFS_SREQ_FAILED, &from->flags) ||
!test_bit(NETFS_SREQ_NEED_RETRY, &from->flags))
return;
list_for_each_continue(next, &stream->subrequests) {
subreq = list_entry(next, struct netfs_io_subrequest, rreq_link);
if (subreq->start + subreq->transferred != start + len ||
test_bit(NETFS_SREQ_BOUNDARY, &subreq->flags) ||
!test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags))
break;
to = subreq;
len += to->len;
}
/* Determine the set of buffers we're going to use. Each
* subreq gets a subset of a single overall contiguous buffer.
*/
netfs_reset_iter(from);
source = from->io_iter;
source.count = len;
/* Work through the sublist. */
subreq = from;
list_for_each_entry_from(subreq, &stream->subrequests, rreq_link) {
if (!len)
break;
subreq->start = start;
subreq->len = len;
__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
subreq->retry_count++;
trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
/* Renegotiate max_len (wsize) */
stream->sreq_max_len = len;
stream->prepare_write(subreq);
part = umin(len, stream->sreq_max_len);
if (unlikely(stream->sreq_max_segs))
part = netfs_limit_iter(&source, 0, part, stream->sreq_max_segs);
subreq->len = part;
subreq->transferred = 0;
len -= part;
start += part;
if (len && subreq == to &&
__test_and_clear_bit(NETFS_SREQ_BOUNDARY, &to->flags))
boundary = true;
netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
netfs_reissue_write(stream, subreq, &source);
if (subreq == to)
break;
}
/* If we managed to use fewer subreqs, we can discard the
* excess; if we used the same number, then we're done.
*/
if (!len) {
if (subreq == to)
continue;
list_for_each_entry_safe_from(subreq, tmp,
&stream->subrequests, rreq_link) {
trace_netfs_sreq(subreq, netfs_sreq_trace_discard);
list_del(&subreq->rreq_link);
netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_done);
if (subreq == to)
break;
}
continue;
}
/* We ran out of subrequests, so we need to allocate some more
* and insert them after.
*/
do {
subreq = netfs_alloc_subrequest(wreq);
subreq->source = to->source;
subreq->start = start;
subreq->debug_index = atomic_inc_return(&wreq->subreq_counter);
subreq->stream_nr = to->stream_nr;
subreq->retry_count = 1;
trace_netfs_sreq_ref(wreq->debug_id, subreq->debug_index,
refcount_read(&subreq->ref),
netfs_sreq_trace_new);
netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
list_add(&subreq->rreq_link, &to->rreq_link);
to = list_next_entry(to, rreq_link);
trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
stream->sreq_max_len = len;
stream->sreq_max_segs = INT_MAX;
switch (stream->source) {
case NETFS_UPLOAD_TO_SERVER:
netfs_stat(&netfs_n_wh_upload);
stream->sreq_max_len = umin(len, wreq->wsize);
break;
case NETFS_WRITE_TO_CACHE:
netfs_stat(&netfs_n_wh_write);
break;
default:
WARN_ON_ONCE(1);
}
stream->prepare_write(subreq);
part = umin(len, stream->sreq_max_len);
subreq->len = subreq->transferred + part;
len -= part;
start += part;
if (!len && boundary) {
__set_bit(NETFS_SREQ_BOUNDARY, &to->flags);
boundary = false;
}
netfs_reissue_write(stream, subreq, &source);
if (!len)
break;
} while (len);
} while (!list_is_head(next, &stream->subrequests));
}
/*
* Perform retries on the streams that need it. If we're doing content
* encryption and the server copy changed due to a third-party write, we may
* need to do an RMW cycle and also rewrite the data to the cache.
*/
void netfs_retry_writes(struct netfs_io_request *wreq)
{
struct netfs_io_subrequest *subreq;
struct netfs_io_stream *stream;
int s;
/* Wait for all outstanding I/O to quiesce before performing retries as
* we may need to renegotiate the I/O sizes.
*/
for (s = 0; s < NR_IO_STREAMS; s++) {
stream = &wreq->io_streams[s];
if (!stream->active)
continue;
list_for_each_entry(subreq, &stream->subrequests, rreq_link) {
wait_on_bit(&subreq->flags, NETFS_SREQ_IN_PROGRESS,
TASK_UNINTERRUPTIBLE);
}
}
// TODO: Enc: Fetch changed partial pages
// TODO: Enc: Reencrypt content if needed.
// TODO: Enc: Wind back transferred point.
// TODO: Enc: Mark cache pages for retry.
for (s = 0; s < NR_IO_STREAMS; s++) {
stream = &wreq->io_streams[s];
if (stream->need_retry) {
stream->need_retry = false;
netfs_retry_write_stream(wreq, stream);
}
}
}
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