[PATCH v5 07/32] netfs: Split retry code out of fs/netfs/write_collect.c

David Howells
2024-12-16T20:42:37Z

Split write-retry code out of fs/netfs/write_collect.c as it will become
more elaborate when content crypto is introduced.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---
fs/netfs/Makefile | 3 +-
fs/netfs/internal.h | 5 +
fs/netfs/write_collect.c | 214 ------------------------------------
fs/netfs/write_retry.c | 226 +++++++++++++++++++++++++++++++++++++++
4 files changed, 233 insertions(+), 215 deletions(-)
create mode 100644 fs/netfs/write_retry.c

diff --git a/fs/netfs/Makefile b/fs/netfs/Makefile
index 7492c4aa331e..cbb30bdeacc4 100644
--- a/fs/netfs/Makefile
+++ b/fs/netfs/Makefile
@@ -15,7 +15,8 @@ netfs-y := \
read_retry.o \
rolling_buffer.o \
write_collect.o \
- write_issue.o
+ write_issue.o \
+ write_retry.o

netfs-$(CONFIG_NETFS_STATS) += stats.o

diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index 6aa2a8d49b37..73887525e939 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -189,6 +189,11 @@ int netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_contr
struct folio *writethrough_cache);
int netfs_unbuffered_write(struct netfs_io_request *wreq, bool may_wait, size_t len);

+/*
+ * write_retry.c
+ */
+void netfs_retry_writes(struct netfs_io_request *wreq);
+
/*
* Miscellaneous functions.
*/
diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c
index 364c1f9d5815..237018caba27 100644
--- a/fs/netfs/write_collect.c
+++ b/fs/netfs/write_collect.c
@@ -151,220 +151,6 @@ static void netfs_writeback_unlock_folios(struct netfs_io_request *wreq,
wreq->buffer.first_tail_slot = slot;
}

-/*
- * 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;
- /* Renegotiate max_len (wsize) */
- trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
- __clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
- subreq->retry_count++;
- stream->prepare_write(subreq);
-
- part = min(len, stream->sreq_max_len);
- subreq->len = part;
- subreq->start = start;
- 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.
- */
-static 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);
- }
- }
-}
-
/*
* Collect and assess the results of various write subrequests. We may need to
* retry some of the results - or even do an RMW cycle for content crypto.
diff --git a/fs/netfs/write_retry.c b/fs/netfs/write_retry.c
new file mode 100644
index 000000000000..f3d5e37d4698
--- /dev/null
+++ b/fs/netfs/write_retry.c
@@ -0,0 +1,226 @@
+// 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;
+ /* Renegotiate max_len (wsize) */
+ trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
+ __clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+ subreq->retry_count++;
+ stream->prepare_write(subreq);
+
+ part = min(len, stream->sreq_max_len);
+ subreq->len = part;
+ subreq->start = start;
+ 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);
+ }
+ }
+}