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Message-ID: <164692918076.2099075.8120961172717347610.stgit@warthog.procyon.org.uk>
Date: Thu, 10 Mar 2022 16:19:40 +0000
From: David Howells <dhowells@...hat.com>
To: linux-cachefs@...hat.com
Cc: Jeff Layton <jlayton@...nel.org>, dhowells@...hat.com,
Anna Schumaker <anna.schumaker@...app.com>,
Steve French <sfrench@...ba.org>,
Dominique Martinet <asmadeus@...ewreck.org>,
Jeff Layton <jlayton@...hat.com>,
David Wysochanski <dwysocha@...hat.com>,
Ilya Dryomov <idryomov@...il.com>,
Jeffle Xu <jefflexu@...ux.alibaba.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
linux-afs@...ts.infradead.org, linux-nfs@...r.kernel.org,
linux-cifs@...r.kernel.org, ceph-devel@...r.kernel.org,
v9fs-developer@...ts.sourceforge.net,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 16/20] netfs: Rename read_helper.c to io.c
Rename the read_helper.c file to io.c before splitting out the buffered
read functions and some other bits.
Changes
=======
ver #2)
- Rename read_helper.c before splitting.
Signed-off-by: David Howells <dhowells@...hat.com>
Reviewed-by: Jeff Layton <jlayton@...nel.org>
cc: linux-cachefs@...hat.com
Link: https://lore.kernel.org/r/164678216109.1200972.16567696909952495832.stgit@warthog.procyon.org.uk/ # v2
---
Documentation/filesystems/netfs_library.rst | 3
fs/netfs/Makefile | 4
fs/netfs/internal.h | 14
fs/netfs/io.c | 1085 +++++++++++++++++++++++++++
fs/netfs/read_helper.c | 1085 ---------------------------
5 files changed, 1096 insertions(+), 1095 deletions(-)
create mode 100644 fs/netfs/io.c
delete mode 100644 fs/netfs/read_helper.c
diff --git a/Documentation/filesystems/netfs_library.rst b/Documentation/filesystems/netfs_library.rst
index 9c8bc5666b46..69f00179fdfe 100644
--- a/Documentation/filesystems/netfs_library.rst
+++ b/Documentation/filesystems/netfs_library.rst
@@ -605,4 +605,5 @@ API Function Reference
======================
.. kernel-doc:: include/linux/netfs.h
-.. kernel-doc:: fs/netfs/read_helper.c
+.. kernel-doc:: fs/netfs/buffered_read.c
+.. kernel-doc:: fs/netfs/io.c
diff --git a/fs/netfs/Makefile b/fs/netfs/Makefile
index 939fd00a1fc9..51ece4f7bc77 100644
--- a/fs/netfs/Makefile
+++ b/fs/netfs/Makefile
@@ -1,8 +1,8 @@
# SPDX-License-Identifier: GPL-2.0
netfs-y := \
- objects.o \
- read_helper.o
+ io.o \
+ objects.o
netfs-$(CONFIG_NETFS_STATS) += stats.o
diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index 11c0c9ef9299..1cd2778bfa7d 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -20,6 +20,13 @@
*/
void netfs_rreq_unlock_folios(struct netfs_io_request *rreq);
+/*
+ * io.c
+ */
+extern unsigned int netfs_debug;
+
+int netfs_begin_read(struct netfs_io_request *rreq, bool sync);
+
/*
* objects.c
*/
@@ -39,13 +46,6 @@ static inline void netfs_see_request(struct netfs_io_request *rreq,
trace_netfs_rreq_ref(rreq->debug_id, refcount_read(&rreq->ref), what);
}
-/*
- * read_helper.c
- */
-extern unsigned int netfs_debug;
-
-int netfs_begin_read(struct netfs_io_request *rreq, bool sync);
-
/*
* stats.c
*/
diff --git a/fs/netfs/io.c b/fs/netfs/io.c
new file mode 100644
index 000000000000..d448dc4f1010
--- /dev/null
+++ b/fs/netfs/io.c
@@ -0,0 +1,1085 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Network filesystem high-level read support.
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@...hat.com)
+ */
+
+#include <linux/module.h>
+#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 "internal.h"
+#define CREATE_TRACE_POINTS
+#include <trace/events/netfs.h>
+
+MODULE_DESCRIPTION("Network fs support");
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_LICENSE("GPL");
+
+unsigned netfs_debug;
+module_param_named(debug, netfs_debug, uint, S_IWUSR | S_IRUGO);
+MODULE_PARM_DESC(netfs_debug, "Netfs support debugging mask");
+
+/*
+ * Clear the unread part of an I/O request.
+ */
+static void netfs_clear_unread(struct netfs_io_subrequest *subreq)
+{
+ struct iov_iter iter;
+
+ iov_iter_xarray(&iter, READ, &subreq->rreq->mapping->i_pages,
+ subreq->start + subreq->transferred,
+ subreq->len - subreq->transferred);
+ iov_iter_zero(iov_iter_count(&iter), &iter);
+}
+
+static void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error,
+ bool was_async)
+{
+ struct netfs_io_subrequest *subreq = priv;
+
+ netfs_subreq_terminated(subreq, transferred_or_error, was_async);
+}
+
+/*
+ * Issue a read against the cache.
+ * - Eats the caller's ref on subreq.
+ */
+static void netfs_read_from_cache(struct netfs_io_request *rreq,
+ struct netfs_io_subrequest *subreq,
+ enum netfs_read_from_hole read_hole)
+{
+ struct netfs_cache_resources *cres = &rreq->cache_resources;
+ struct iov_iter iter;
+
+ netfs_stat(&netfs_n_rh_read);
+ iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
+ subreq->start + subreq->transferred,
+ subreq->len - subreq->transferred);
+
+ cres->ops->read(cres, subreq->start, &iter, read_hole,
+ netfs_cache_read_terminated, subreq);
+}
+
+/*
+ * Fill a subrequest region with zeroes.
+ */
+static void netfs_fill_with_zeroes(struct netfs_io_request *rreq,
+ struct netfs_io_subrequest *subreq)
+{
+ netfs_stat(&netfs_n_rh_zero);
+ __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
+ netfs_subreq_terminated(subreq, 0, false);
+}
+
+/*
+ * Ask the netfs to issue a read request to the server for us.
+ *
+ * The netfs is expected to read from subreq->pos + subreq->transferred to
+ * subreq->pos + subreq->len - 1. It may not backtrack and write data into the
+ * buffer prior to the transferred point as it might clobber dirty data
+ * obtained from the cache.
+ *
+ * Alternatively, the netfs is allowed to indicate one of two things:
+ *
+ * - NETFS_SREQ_SHORT_READ: A short read - it will get called again to try and
+ * make progress.
+ *
+ * - NETFS_SREQ_CLEAR_TAIL: A short read - the rest of the buffer will be
+ * cleared.
+ */
+static void netfs_read_from_server(struct netfs_io_request *rreq,
+ struct netfs_io_subrequest *subreq)
+{
+ netfs_stat(&netfs_n_rh_download);
+ rreq->netfs_ops->issue_read(subreq);
+}
+
+/*
+ * Release those waiting.
+ */
+static void netfs_rreq_completed(struct netfs_io_request *rreq, bool was_async)
+{
+ trace_netfs_rreq(rreq, netfs_rreq_trace_done);
+ netfs_clear_subrequests(rreq, was_async);
+ netfs_put_request(rreq, was_async, netfs_rreq_trace_put_complete);
+}
+
+/*
+ * Deal with the completion of writing the data to the cache. We have to clear
+ * the PG_fscache bits on the folios involved and release the caller's ref.
+ *
+ * May be called in softirq mode and we inherit a ref from the caller.
+ */
+static void netfs_rreq_unmark_after_write(struct netfs_io_request *rreq,
+ bool was_async)
+{
+ struct netfs_io_subrequest *subreq;
+ struct folio *folio;
+ pgoff_t unlocked = 0;
+ bool have_unlocked = false;
+
+ rcu_read_lock();
+
+ list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+ XA_STATE(xas, &rreq->mapping->i_pages, subreq->start / PAGE_SIZE);
+
+ xas_for_each(&xas, folio, (subreq->start + subreq->len - 1) / PAGE_SIZE) {
+ /* We might have multiple writes from the same huge
+ * folio, but we mustn't unlock a folio more than once.
+ */
+ if (have_unlocked && folio_index(folio) <= unlocked)
+ continue;
+ unlocked = folio_index(folio);
+ folio_end_fscache(folio);
+ have_unlocked = true;
+ }
+ }
+
+ rcu_read_unlock();
+ netfs_rreq_completed(rreq, was_async);
+}
+
+static void netfs_rreq_copy_terminated(void *priv, ssize_t transferred_or_error,
+ bool was_async)
+{
+ struct netfs_io_subrequest *subreq = priv;
+ struct netfs_io_request *rreq = subreq->rreq;
+
+ if (IS_ERR_VALUE(transferred_or_error)) {
+ netfs_stat(&netfs_n_rh_write_failed);
+ trace_netfs_failure(rreq, subreq, transferred_or_error,
+ netfs_fail_copy_to_cache);
+ } else {
+ netfs_stat(&netfs_n_rh_write_done);
+ }
+
+ trace_netfs_sreq(subreq, netfs_sreq_trace_write_term);
+
+ /* If we decrement nr_copy_ops to 0, the ref belongs to us. */
+ if (atomic_dec_and_test(&rreq->nr_copy_ops))
+ netfs_rreq_unmark_after_write(rreq, was_async);
+
+ netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);
+}
+
+/*
+ * Perform any outstanding writes to the cache. We inherit a ref from the
+ * caller.
+ */
+static void netfs_rreq_do_write_to_cache(struct netfs_io_request *rreq)
+{
+ struct netfs_cache_resources *cres = &rreq->cache_resources;
+ struct netfs_io_subrequest *subreq, *next, *p;
+ struct iov_iter iter;
+ int ret;
+
+ trace_netfs_rreq(rreq, netfs_rreq_trace_copy);
+
+ /* We don't want terminating writes trying to wake us up whilst we're
+ * still going through the list.
+ */
+ atomic_inc(&rreq->nr_copy_ops);
+
+ list_for_each_entry_safe(subreq, p, &rreq->subrequests, rreq_link) {
+ if (!test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags)) {
+ list_del_init(&subreq->rreq_link);
+ netfs_put_subrequest(subreq, false,
+ netfs_sreq_trace_put_no_copy);
+ }
+ }
+
+ list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+ /* Amalgamate adjacent writes */
+ while (!list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
+ next = list_next_entry(subreq, rreq_link);
+ if (next->start != subreq->start + subreq->len)
+ break;
+ subreq->len += next->len;
+ list_del_init(&next->rreq_link);
+ netfs_put_subrequest(next, false,
+ netfs_sreq_trace_put_merged);
+ }
+
+ ret = cres->ops->prepare_write(cres, &subreq->start, &subreq->len,
+ rreq->i_size, true);
+ if (ret < 0) {
+ trace_netfs_failure(rreq, subreq, ret, netfs_fail_prepare_write);
+ trace_netfs_sreq(subreq, netfs_sreq_trace_write_skip);
+ continue;
+ }
+
+ iov_iter_xarray(&iter, WRITE, &rreq->mapping->i_pages,
+ subreq->start, subreq->len);
+
+ atomic_inc(&rreq->nr_copy_ops);
+ netfs_stat(&netfs_n_rh_write);
+ netfs_get_subrequest(subreq, netfs_sreq_trace_get_copy_to_cache);
+ trace_netfs_sreq(subreq, netfs_sreq_trace_write);
+ cres->ops->write(cres, subreq->start, &iter,
+ netfs_rreq_copy_terminated, subreq);
+ }
+
+ /* If we decrement nr_copy_ops to 0, the usage ref belongs to us. */
+ if (atomic_dec_and_test(&rreq->nr_copy_ops))
+ netfs_rreq_unmark_after_write(rreq, false);
+}
+
+static void netfs_rreq_write_to_cache_work(struct work_struct *work)
+{
+ struct netfs_io_request *rreq =
+ container_of(work, struct netfs_io_request, work);
+
+ netfs_rreq_do_write_to_cache(rreq);
+}
+
+static void netfs_rreq_write_to_cache(struct netfs_io_request *rreq)
+{
+ rreq->work.func = netfs_rreq_write_to_cache_work;
+ if (!queue_work(system_unbound_wq, &rreq->work))
+ BUG();
+}
+
+/*
+ * Unlock the folios in a read operation. We need to set PG_fscache on any
+ * folios we're going to write back before we unlock them.
+ */
+void netfs_rreq_unlock_folios(struct netfs_io_request *rreq)
+{
+ struct netfs_io_subrequest *subreq;
+ struct folio *folio;
+ unsigned int iopos, account = 0;
+ pgoff_t start_page = rreq->start / PAGE_SIZE;
+ pgoff_t last_page = ((rreq->start + rreq->len) / PAGE_SIZE) - 1;
+ bool subreq_failed = false;
+
+ XA_STATE(xas, &rreq->mapping->i_pages, start_page);
+
+ if (test_bit(NETFS_RREQ_FAILED, &rreq->flags)) {
+ __clear_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags);
+ list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+ __clear_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags);
+ }
+ }
+
+ /* Walk through the pagecache and the I/O request lists simultaneously.
+ * We may have a mixture of cached and uncached sections and we only
+ * really want to write out the uncached sections. This is slightly
+ * complicated by the possibility that we might have huge pages with a
+ * mixture inside.
+ */
+ subreq = list_first_entry(&rreq->subrequests,
+ struct netfs_io_subrequest, rreq_link);
+ iopos = 0;
+ subreq_failed = (subreq->error < 0);
+
+ trace_netfs_rreq(rreq, netfs_rreq_trace_unlock);
+
+ rcu_read_lock();
+ xas_for_each(&xas, folio, last_page) {
+ unsigned int pgpos = (folio_index(folio) - start_page) * PAGE_SIZE;
+ unsigned int pgend = pgpos + folio_size(folio);
+ bool pg_failed = false;
+
+ for (;;) {
+ if (!subreq) {
+ pg_failed = true;
+ break;
+ }
+ if (test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags))
+ folio_start_fscache(folio);
+ pg_failed |= subreq_failed;
+ if (pgend < iopos + subreq->len)
+ break;
+
+ account += subreq->transferred;
+ iopos += subreq->len;
+ if (!list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
+ subreq = list_next_entry(subreq, rreq_link);
+ subreq_failed = (subreq->error < 0);
+ } else {
+ subreq = NULL;
+ subreq_failed = false;
+ }
+ if (pgend == iopos)
+ break;
+ }
+
+ if (!pg_failed) {
+ flush_dcache_folio(folio);
+ folio_mark_uptodate(folio);
+ }
+
+ if (!test_bit(NETFS_RREQ_DONT_UNLOCK_FOLIOS, &rreq->flags)) {
+ if (folio_index(folio) == rreq->no_unlock_folio &&
+ test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags))
+ _debug("no unlock");
+ else
+ folio_unlock(folio);
+ }
+ }
+ rcu_read_unlock();
+
+ task_io_account_read(account);
+ if (rreq->netfs_ops->done)
+ rreq->netfs_ops->done(rreq);
+}
+
+/*
+ * Handle a short read.
+ */
+static void netfs_rreq_short_read(struct netfs_io_request *rreq,
+ struct netfs_io_subrequest *subreq)
+{
+ __clear_bit(NETFS_SREQ_SHORT_IO, &subreq->flags);
+ __set_bit(NETFS_SREQ_SEEK_DATA_READ, &subreq->flags);
+
+ netfs_stat(&netfs_n_rh_short_read);
+ trace_netfs_sreq(subreq, netfs_sreq_trace_resubmit_short);
+
+ netfs_get_subrequest(subreq, netfs_sreq_trace_get_short_read);
+ atomic_inc(&rreq->nr_outstanding);
+ if (subreq->source == NETFS_READ_FROM_CACHE)
+ netfs_read_from_cache(rreq, subreq, NETFS_READ_HOLE_CLEAR);
+ else
+ netfs_read_from_server(rreq, subreq);
+}
+
+/*
+ * Resubmit any short or failed operations. Returns true if we got the rreq
+ * ref back.
+ */
+static bool netfs_rreq_perform_resubmissions(struct netfs_io_request *rreq)
+{
+ struct netfs_io_subrequest *subreq;
+
+ WARN_ON(in_interrupt());
+
+ trace_netfs_rreq(rreq, netfs_rreq_trace_resubmit);
+
+ /* We don't want terminating submissions trying to wake us up whilst
+ * we're still going through the list.
+ */
+ atomic_inc(&rreq->nr_outstanding);
+
+ __clear_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
+ list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+ if (subreq->error) {
+ if (subreq->source != NETFS_READ_FROM_CACHE)
+ break;
+ subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
+ subreq->error = 0;
+ netfs_stat(&netfs_n_rh_download_instead);
+ trace_netfs_sreq(subreq, netfs_sreq_trace_download_instead);
+ netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
+ atomic_inc(&rreq->nr_outstanding);
+ netfs_read_from_server(rreq, subreq);
+ } else if (test_bit(NETFS_SREQ_SHORT_IO, &subreq->flags)) {
+ netfs_rreq_short_read(rreq, subreq);
+ }
+ }
+
+ /* If we decrement nr_outstanding to 0, the usage ref belongs to us. */
+ if (atomic_dec_and_test(&rreq->nr_outstanding))
+ return true;
+
+ wake_up_var(&rreq->nr_outstanding);
+ return false;
+}
+
+/*
+ * Check to see if the data read is still valid.
+ */
+static void netfs_rreq_is_still_valid(struct netfs_io_request *rreq)
+{
+ struct netfs_io_subrequest *subreq;
+
+ if (!rreq->netfs_ops->is_still_valid ||
+ rreq->netfs_ops->is_still_valid(rreq))
+ return;
+
+ list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+ if (subreq->source == NETFS_READ_FROM_CACHE) {
+ subreq->error = -ESTALE;
+ __set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
+ }
+ }
+}
+
+/*
+ * Assess the state of a read request and decide what to do next.
+ *
+ * Note that we could be in an ordinary kernel thread, on a workqueue or in
+ * softirq context at this point. We inherit a ref from the caller.
+ */
+static void netfs_rreq_assess(struct netfs_io_request *rreq, bool was_async)
+{
+ trace_netfs_rreq(rreq, netfs_rreq_trace_assess);
+
+again:
+ netfs_rreq_is_still_valid(rreq);
+
+ if (!test_bit(NETFS_RREQ_FAILED, &rreq->flags) &&
+ test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags)) {
+ if (netfs_rreq_perform_resubmissions(rreq))
+ goto again;
+ return;
+ }
+
+ netfs_rreq_unlock_folios(rreq);
+
+ clear_bit_unlock(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
+ wake_up_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS);
+
+ if (test_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags))
+ return netfs_rreq_write_to_cache(rreq);
+
+ netfs_rreq_completed(rreq, was_async);
+}
+
+static void netfs_rreq_work(struct work_struct *work)
+{
+ struct netfs_io_request *rreq =
+ container_of(work, struct netfs_io_request, work);
+ netfs_rreq_assess(rreq, false);
+}
+
+/*
+ * Handle the completion of all outstanding I/O operations on a read request.
+ * We inherit a ref from the caller.
+ */
+static void netfs_rreq_terminated(struct netfs_io_request *rreq,
+ bool was_async)
+{
+ if (test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags) &&
+ was_async) {
+ if (!queue_work(system_unbound_wq, &rreq->work))
+ BUG();
+ } else {
+ netfs_rreq_assess(rreq, was_async);
+ }
+}
+
+/**
+ * netfs_subreq_terminated - Note the termination of an I/O operation.
+ * @subreq: The I/O request that has terminated.
+ * @transferred_or_error: The amount of data transferred or an error code.
+ * @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 in @transferred_or_error the outcome of the operation,
+ * supplying a positive value to indicate the number of bytes transferred, 0 to
+ * indicate a failure to transfer anything that should be retried or a negative
+ * error code. The helper will look after reissuing I/O operations as
+ * appropriate and writing downloaded data to the cache.
+ *
+ * If @was_async is true, the caller might be running in softirq or interrupt
+ * context and we can't sleep.
+ */
+void netfs_subreq_terminated(struct netfs_io_subrequest *subreq,
+ ssize_t transferred_or_error,
+ bool was_async)
+{
+ struct netfs_io_request *rreq = subreq->rreq;
+ int u;
+
+ _enter("[%u]{%llx,%lx},%zd",
+ subreq->debug_index, subreq->start, subreq->flags,
+ transferred_or_error);
+
+ switch (subreq->source) {
+ case NETFS_READ_FROM_CACHE:
+ netfs_stat(&netfs_n_rh_read_done);
+ break;
+ case NETFS_DOWNLOAD_FROM_SERVER:
+ netfs_stat(&netfs_n_rh_download_done);
+ break;
+ default:
+ break;
+ }
+
+ if (IS_ERR_VALUE(transferred_or_error)) {
+ subreq->error = transferred_or_error;
+ trace_netfs_failure(rreq, subreq, transferred_or_error,
+ netfs_fail_read);
+ goto failed;
+ }
+
+ if (WARN(transferred_or_error > subreq->len - subreq->transferred,
+ "Subreq overread: R%x[%x] %zd > %zu - %zu",
+ rreq->debug_id, subreq->debug_index,
+ transferred_or_error, subreq->len, subreq->transferred))
+ transferred_or_error = subreq->len - subreq->transferred;
+
+ subreq->error = 0;
+ subreq->transferred += transferred_or_error;
+ if (subreq->transferred < subreq->len)
+ goto incomplete;
+
+complete:
+ __clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+ if (test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags))
+ set_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags);
+
+out:
+ trace_netfs_sreq(subreq, netfs_sreq_trace_terminated);
+
+ /* If we decrement nr_outstanding to 0, the ref belongs to us. */
+ u = atomic_dec_return(&rreq->nr_outstanding);
+ if (u == 0)
+ netfs_rreq_terminated(rreq, was_async);
+ else if (u == 1)
+ wake_up_var(&rreq->nr_outstanding);
+
+ netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);
+ return;
+
+incomplete:
+ if (test_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags)) {
+ netfs_clear_unread(subreq);
+ subreq->transferred = subreq->len;
+ goto complete;
+ }
+
+ if (transferred_or_error == 0) {
+ if (__test_and_set_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags)) {
+ subreq->error = -ENODATA;
+ goto failed;
+ }
+ } else {
+ __clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+ }
+
+ __set_bit(NETFS_SREQ_SHORT_IO, &subreq->flags);
+ set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
+ goto out;
+
+failed:
+ if (subreq->source == NETFS_READ_FROM_CACHE) {
+ netfs_stat(&netfs_n_rh_read_failed);
+ set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
+ } else {
+ netfs_stat(&netfs_n_rh_download_failed);
+ set_bit(NETFS_RREQ_FAILED, &rreq->flags);
+ rreq->error = subreq->error;
+ }
+ goto out;
+}
+EXPORT_SYMBOL(netfs_subreq_terminated);
+
+static enum netfs_io_source netfs_cache_prepare_read(struct netfs_io_subrequest *subreq,
+ loff_t i_size)
+{
+ struct netfs_io_request *rreq = subreq->rreq;
+ struct netfs_cache_resources *cres = &rreq->cache_resources;
+
+ if (cres->ops)
+ return cres->ops->prepare_read(subreq, i_size);
+ if (subreq->start >= rreq->i_size)
+ return NETFS_FILL_WITH_ZEROES;
+ return NETFS_DOWNLOAD_FROM_SERVER;
+}
+
+/*
+ * Work out what sort of subrequest the next one will be.
+ */
+static enum netfs_io_source
+netfs_rreq_prepare_read(struct netfs_io_request *rreq,
+ struct netfs_io_subrequest *subreq)
+{
+ enum netfs_io_source source;
+
+ _enter("%llx-%llx,%llx", subreq->start, subreq->start + subreq->len, rreq->i_size);
+
+ source = netfs_cache_prepare_read(subreq, rreq->i_size);
+ if (source == NETFS_INVALID_READ)
+ goto out;
+
+ if (source == NETFS_DOWNLOAD_FROM_SERVER) {
+ /* Call out to the netfs to let it shrink the request to fit
+ * its own I/O sizes and boundaries. If it shinks it here, it
+ * will be called again to make simultaneous calls; if it wants
+ * to make serial calls, it can indicate a short read and then
+ * we will call it again.
+ */
+ if (subreq->len > rreq->i_size - subreq->start)
+ subreq->len = rreq->i_size - subreq->start;
+
+ if (rreq->netfs_ops->clamp_length &&
+ !rreq->netfs_ops->clamp_length(subreq)) {
+ source = NETFS_INVALID_READ;
+ goto out;
+ }
+ }
+
+ if (WARN_ON(subreq->len == 0))
+ source = NETFS_INVALID_READ;
+
+out:
+ subreq->source = source;
+ trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
+ return source;
+}
+
+/*
+ * Slice off a piece of a read request and submit an I/O request for it.
+ */
+static bool netfs_rreq_submit_slice(struct netfs_io_request *rreq,
+ unsigned int *_debug_index)
+{
+ struct netfs_io_subrequest *subreq;
+ enum netfs_io_source source;
+
+ subreq = netfs_alloc_subrequest(rreq);
+ if (!subreq)
+ return false;
+
+ subreq->debug_index = (*_debug_index)++;
+ subreq->start = rreq->start + rreq->submitted;
+ subreq->len = rreq->len - rreq->submitted;
+
+ _debug("slice %llx,%zx,%zx", subreq->start, subreq->len, rreq->submitted);
+ list_add_tail(&subreq->rreq_link, &rreq->subrequests);
+
+ /* Call out to the cache to find out what it can do with the remaining
+ * subset. It tells us in subreq->flags what it decided should be done
+ * and adjusts subreq->len down if the subset crosses a cache boundary.
+ *
+ * Then when we hand the subset, it can choose to take a subset of that
+ * (the starts must coincide), in which case, we go around the loop
+ * again and ask it to download the next piece.
+ */
+ source = netfs_rreq_prepare_read(rreq, subreq);
+ if (source == NETFS_INVALID_READ)
+ goto subreq_failed;
+
+ atomic_inc(&rreq->nr_outstanding);
+
+ rreq->submitted += subreq->len;
+
+ trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
+ switch (source) {
+ case NETFS_FILL_WITH_ZEROES:
+ netfs_fill_with_zeroes(rreq, subreq);
+ break;
+ case NETFS_DOWNLOAD_FROM_SERVER:
+ netfs_read_from_server(rreq, subreq);
+ break;
+ case NETFS_READ_FROM_CACHE:
+ netfs_read_from_cache(rreq, subreq, NETFS_READ_HOLE_IGNORE);
+ break;
+ default:
+ BUG();
+ }
+
+ return true;
+
+subreq_failed:
+ rreq->error = subreq->error;
+ netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_failed);
+ return false;
+}
+
+/*
+ * Begin the process of reading in a chunk of data, where that data may be
+ * stitched together from multiple sources, including multiple servers and the
+ * local cache.
+ */
+int netfs_begin_read(struct netfs_io_request *rreq, bool sync)
+{
+ unsigned int debug_index = 0;
+ int ret;
+
+ _enter("R=%x %llx-%llx",
+ rreq->debug_id, rreq->start, rreq->start + rreq->len - 1);
+
+ if (rreq->len == 0) {
+ pr_err("Zero-sized read [R=%x]\n", rreq->debug_id);
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_zero_len);
+ return -EIO;
+ }
+
+ INIT_WORK(&rreq->work, netfs_rreq_work);
+
+ if (sync)
+ netfs_get_request(rreq, netfs_rreq_trace_get_hold);
+
+ /* Chop the read into slices according to what the cache and the netfs
+ * want and submit each one.
+ */
+ atomic_set(&rreq->nr_outstanding, 1);
+ do {
+ if (!netfs_rreq_submit_slice(rreq, &debug_index))
+ break;
+
+ } while (rreq->submitted < rreq->len);
+
+ if (sync) {
+ /* Keep nr_outstanding incremented so that the ref always belongs to
+ * us, and the service code isn't punted off to a random thread pool to
+ * process.
+ */
+ for (;;) {
+ wait_var_event(&rreq->nr_outstanding,
+ atomic_read(&rreq->nr_outstanding) == 1);
+ netfs_rreq_assess(rreq, false);
+ if (!test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags))
+ break;
+ cond_resched();
+ }
+
+ ret = rreq->error;
+ if (ret == 0 && rreq->submitted < rreq->len) {
+ trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_read);
+ ret = -EIO;
+ }
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);
+ } else {
+ /* If we decrement nr_outstanding to 0, the ref belongs to us. */
+ if (atomic_dec_and_test(&rreq->nr_outstanding))
+ netfs_rreq_assess(rreq, false);
+ ret = 0;
+ }
+ return ret;
+}
+
+static void netfs_cache_expand_readahead(struct netfs_io_request *rreq,
+ loff_t *_start, size_t *_len, loff_t i_size)
+{
+ struct netfs_cache_resources *cres = &rreq->cache_resources;
+
+ if (cres->ops && cres->ops->expand_readahead)
+ cres->ops->expand_readahead(cres, _start, _len, i_size);
+}
+
+static void netfs_rreq_expand(struct netfs_io_request *rreq,
+ struct readahead_control *ractl)
+{
+ /* Give the cache a chance to change the request parameters. The
+ * resultant request must contain the original region.
+ */
+ netfs_cache_expand_readahead(rreq, &rreq->start, &rreq->len, rreq->i_size);
+
+ /* Give the netfs a chance to change the request parameters. The
+ * resultant request must contain the original region.
+ */
+ if (rreq->netfs_ops->expand_readahead)
+ rreq->netfs_ops->expand_readahead(rreq);
+
+ /* Expand the request if the cache wants it to start earlier. Note
+ * that the expansion may get further extended if the VM wishes to
+ * insert THPs and the preferred start and/or end wind up in the middle
+ * of THPs.
+ *
+ * If this is the case, however, the THP size should be an integer
+ * multiple of the cache granule size, so we get a whole number of
+ * granules to deal with.
+ */
+ if (rreq->start != readahead_pos(ractl) ||
+ rreq->len != readahead_length(ractl)) {
+ readahead_expand(ractl, rreq->start, rreq->len);
+ rreq->start = readahead_pos(ractl);
+ rreq->len = readahead_length(ractl);
+
+ trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
+ netfs_read_trace_expanded);
+ }
+}
+
+/**
+ * netfs_readahead - Helper to manage a read request
+ * @ractl: The description of the readahead request
+ *
+ * Fulfil a readahead request by drawing data from the cache if possible, or
+ * the netfs if not. Space beyond the EOF is zero-filled. Multiple I/O
+ * requests from different sources will get munged together. If necessary, the
+ * readahead window can be expanded in either direction to a more convenient
+ * alighment for RPC efficiency or to make storage in the cache feasible.
+ *
+ * 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.
+ */
+void netfs_readahead(struct readahead_control *ractl)
+{
+ struct netfs_io_request *rreq;
+ struct netfs_i_context *ctx = netfs_i_context(ractl->mapping->host);
+ int ret;
+
+ _enter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
+
+ if (readahead_count(ractl) == 0)
+ return;
+
+ rreq = netfs_alloc_request(ractl->mapping, ractl->file,
+ readahead_pos(ractl),
+ readahead_length(ractl),
+ NETFS_READAHEAD);
+ if (IS_ERR(rreq))
+ return;
+
+ if (ctx->ops->begin_cache_operation) {
+ ret = ctx->ops->begin_cache_operation(rreq);
+ if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
+ goto cleanup_free;
+ }
+
+ netfs_stat(&netfs_n_rh_readahead);
+ trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
+ netfs_read_trace_readahead);
+
+ netfs_rreq_expand(rreq, ractl);
+
+ /* Drop the refs on the folios here rather than in the cache or
+ * filesystem. The locks will be dropped in netfs_rreq_unlock().
+ */
+ while (readahead_folio(ractl))
+ ;
+
+ netfs_begin_read(rreq, false);
+ return;
+
+cleanup_free:
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
+ return;
+}
+EXPORT_SYMBOL(netfs_readahead);
+
+/**
+ * netfs_readpage - Helper to manage a readpage request
+ * @file: The file to read from
+ * @subpage: A subpage of the folio to read
+ *
+ * Fulfil a readpage request by drawing data from the cache if possible, or the
+ * netfs if not. Space beyond the EOF is zero-filled. Multiple I/O requests
+ * from different sources will get munged together.
+ *
+ * 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.
+ */
+int netfs_readpage(struct file *file, struct page *subpage)
+{
+ struct folio *folio = page_folio(subpage);
+ struct address_space *mapping = folio->mapping;
+ struct netfs_io_request *rreq;
+ struct netfs_i_context *ctx = netfs_i_context(mapping->host);
+ int ret;
+
+ _enter("%lx", folio_index(folio));
+
+ rreq = netfs_alloc_request(mapping, file,
+ folio_file_pos(folio), folio_size(folio),
+ NETFS_READPAGE);
+ if (IS_ERR(rreq)) {
+ ret = PTR_ERR(rreq);
+ goto alloc_error;
+ }
+
+ if (ctx->ops->begin_cache_operation) {
+ ret = ctx->ops->begin_cache_operation(rreq);
+ if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
+ goto discard;
+ }
+
+ netfs_stat(&netfs_n_rh_readpage);
+ trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
+ return netfs_begin_read(rreq, true);
+
+discard:
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_discard);
+alloc_error:
+ folio_unlock(folio);
+ return ret;
+}
+EXPORT_SYMBOL(netfs_readpage);
+
+/*
+ * Prepare a folio for writing without reading first
+ * @folio: The folio being prepared
+ * @pos: starting position for the write
+ * @len: length of write
+ * @always_fill: T if the folio should always be completely filled/cleared
+ *
+ * In some cases, write_begin doesn't need to read at all:
+ * - full folio write
+ * - write that lies in a folio that is completely beyond EOF
+ * - write that covers the folio from start to EOF or beyond it
+ *
+ * If any of these criteria are met, then zero out the unwritten parts
+ * of the folio and return true. Otherwise, return false.
+ */
+static bool netfs_skip_folio_read(struct folio *folio, loff_t pos, size_t len,
+ bool always_fill)
+{
+ struct inode *inode = folio_inode(folio);
+ loff_t i_size = i_size_read(inode);
+ size_t offset = offset_in_folio(folio, pos);
+ size_t plen = folio_size(folio);
+
+ if (unlikely(always_fill)) {
+ if (pos - offset + len <= i_size)
+ return false; /* Page entirely before EOF */
+ zero_user_segment(&folio->page, 0, plen);
+ folio_mark_uptodate(folio);
+ return true;
+ }
+
+ /* Full folio write */
+ if (offset == 0 && len >= plen)
+ return true;
+
+ /* Page entirely beyond the end of the file */
+ if (pos - offset >= i_size)
+ goto zero_out;
+
+ /* Write that covers from the start of the folio to EOF or beyond */
+ if (offset == 0 && (pos + len) >= i_size)
+ goto zero_out;
+
+ return false;
+zero_out:
+ zero_user_segments(&folio->page, 0, offset, offset + len, len);
+ return true;
+}
+
+/**
+ * netfs_write_begin - Helper to prepare for writing
+ * @file: The file to read from
+ * @mapping: The mapping to read from
+ * @pos: File position at which the write will begin
+ * @len: The length of the write (may extend beyond the end of the folio chosen)
+ * @aop_flags: AOP_* flags
+ * @_folio: Where to put the resultant folio
+ * @_fsdata: Place for the netfs to store a cookie
+ *
+ * Pre-read data for a write-begin request by drawing data from the cache if
+ * possible, or the netfs if not. Space beyond the EOF is zero-filled.
+ * Multiple I/O requests from different sources will get munged together. If
+ * necessary, the readahead window can be expanded in either direction to a
+ * more convenient alighment for RPC efficiency or to make storage in the cache
+ * feasible.
+ *
+ * The calling netfs must provide a table of operations, only one of which,
+ * issue_op, is mandatory.
+ *
+ * The check_write_begin() operation can be provided to check for and flush
+ * conflicting writes once the folio is grabbed and locked. It is passed a
+ * pointer to the fsdata cookie that gets returned to the VM to be passed to
+ * write_end. It is permitted to sleep. It should return 0 if the request
+ * should go ahead; unlock the folio and return -EAGAIN to cause the folio to
+ * be regot; or return an error.
+ *
+ * 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.
+ */
+int netfs_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned int len, unsigned int aop_flags,
+ struct folio **_folio, void **_fsdata)
+{
+ struct netfs_io_request *rreq;
+ struct netfs_i_context *ctx = netfs_i_context(file_inode(file ));
+ struct folio *folio;
+ unsigned int fgp_flags;
+ pgoff_t index = pos >> PAGE_SHIFT;
+ int ret;
+
+ DEFINE_READAHEAD(ractl, file, NULL, mapping, index);
+
+retry:
+ fgp_flags = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE;
+ if (aop_flags & AOP_FLAG_NOFS)
+ fgp_flags |= FGP_NOFS;
+ folio = __filemap_get_folio(mapping, index, fgp_flags,
+ mapping_gfp_mask(mapping));
+ if (!folio)
+ return -ENOMEM;
+
+ if (ctx->ops->check_write_begin) {
+ /* Allow the netfs (eg. ceph) to flush conflicts. */
+ ret = ctx->ops->check_write_begin(file, pos, len, folio, _fsdata);
+ if (ret < 0) {
+ trace_netfs_failure(NULL, NULL, ret, netfs_fail_check_write_begin);
+ if (ret == -EAGAIN)
+ goto retry;
+ goto error;
+ }
+ }
+
+ if (folio_test_uptodate(folio))
+ goto have_folio;
+
+ /* If the page is beyond the EOF, we want to clear it - unless it's
+ * within the cache granule containing the EOF, in which case we need
+ * to preload the granule.
+ */
+ if (!netfs_is_cache_enabled(ctx) &&
+ netfs_skip_folio_read(folio, pos, len, false)) {
+ netfs_stat(&netfs_n_rh_write_zskip);
+ goto have_folio_no_wait;
+ }
+
+ rreq = netfs_alloc_request(mapping, file,
+ folio_file_pos(folio), folio_size(folio),
+ NETFS_READ_FOR_WRITE);
+ if (IS_ERR(rreq)) {
+ ret = PTR_ERR(rreq);
+ goto error;
+ }
+ rreq->no_unlock_folio = folio_index(folio);
+ __set_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags);
+
+ if (ctx->ops->begin_cache_operation) {
+ ret = ctx->ops->begin_cache_operation(rreq);
+ if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
+ goto error_put;
+ }
+
+ netfs_stat(&netfs_n_rh_write_begin);
+ trace_netfs_read(rreq, pos, len, netfs_read_trace_write_begin);
+
+ /* Expand the request to meet caching requirements and download
+ * preferences.
+ */
+ ractl._nr_pages = folio_nr_pages(folio);
+ netfs_rreq_expand(rreq, &ractl);
+
+ /* We hold the folio locks, so we can drop the references */
+ folio_get(folio);
+ while (readahead_folio(&ractl))
+ ;
+
+ ret = netfs_begin_read(rreq, true);
+ if (ret < 0)
+ goto error;
+
+have_folio:
+ ret = folio_wait_fscache_killable(folio);
+ if (ret < 0)
+ goto error;
+have_folio_no_wait:
+ *_folio = folio;
+ _leave(" = 0");
+ return 0;
+
+error_put:
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
+error:
+ folio_unlock(folio);
+ folio_put(folio);
+ _leave(" = %d", ret);
+ return ret;
+}
+EXPORT_SYMBOL(netfs_write_begin);
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
deleted file mode 100644
index d448dc4f1010..000000000000
--- a/fs/netfs/read_helper.c
+++ /dev/null
@@ -1,1085 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/* Network filesystem high-level read support.
- *
- * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@...hat.com)
- */
-
-#include <linux/module.h>
-#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 "internal.h"
-#define CREATE_TRACE_POINTS
-#include <trace/events/netfs.h>
-
-MODULE_DESCRIPTION("Network fs support");
-MODULE_AUTHOR("Red Hat, Inc.");
-MODULE_LICENSE("GPL");
-
-unsigned netfs_debug;
-module_param_named(debug, netfs_debug, uint, S_IWUSR | S_IRUGO);
-MODULE_PARM_DESC(netfs_debug, "Netfs support debugging mask");
-
-/*
- * Clear the unread part of an I/O request.
- */
-static void netfs_clear_unread(struct netfs_io_subrequest *subreq)
-{
- struct iov_iter iter;
-
- iov_iter_xarray(&iter, READ, &subreq->rreq->mapping->i_pages,
- subreq->start + subreq->transferred,
- subreq->len - subreq->transferred);
- iov_iter_zero(iov_iter_count(&iter), &iter);
-}
-
-static void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error,
- bool was_async)
-{
- struct netfs_io_subrequest *subreq = priv;
-
- netfs_subreq_terminated(subreq, transferred_or_error, was_async);
-}
-
-/*
- * Issue a read against the cache.
- * - Eats the caller's ref on subreq.
- */
-static void netfs_read_from_cache(struct netfs_io_request *rreq,
- struct netfs_io_subrequest *subreq,
- enum netfs_read_from_hole read_hole)
-{
- struct netfs_cache_resources *cres = &rreq->cache_resources;
- struct iov_iter iter;
-
- netfs_stat(&netfs_n_rh_read);
- iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
- subreq->start + subreq->transferred,
- subreq->len - subreq->transferred);
-
- cres->ops->read(cres, subreq->start, &iter, read_hole,
- netfs_cache_read_terminated, subreq);
-}
-
-/*
- * Fill a subrequest region with zeroes.
- */
-static void netfs_fill_with_zeroes(struct netfs_io_request *rreq,
- struct netfs_io_subrequest *subreq)
-{
- netfs_stat(&netfs_n_rh_zero);
- __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
- netfs_subreq_terminated(subreq, 0, false);
-}
-
-/*
- * Ask the netfs to issue a read request to the server for us.
- *
- * The netfs is expected to read from subreq->pos + subreq->transferred to
- * subreq->pos + subreq->len - 1. It may not backtrack and write data into the
- * buffer prior to the transferred point as it might clobber dirty data
- * obtained from the cache.
- *
- * Alternatively, the netfs is allowed to indicate one of two things:
- *
- * - NETFS_SREQ_SHORT_READ: A short read - it will get called again to try and
- * make progress.
- *
- * - NETFS_SREQ_CLEAR_TAIL: A short read - the rest of the buffer will be
- * cleared.
- */
-static void netfs_read_from_server(struct netfs_io_request *rreq,
- struct netfs_io_subrequest *subreq)
-{
- netfs_stat(&netfs_n_rh_download);
- rreq->netfs_ops->issue_read(subreq);
-}
-
-/*
- * Release those waiting.
- */
-static void netfs_rreq_completed(struct netfs_io_request *rreq, bool was_async)
-{
- trace_netfs_rreq(rreq, netfs_rreq_trace_done);
- netfs_clear_subrequests(rreq, was_async);
- netfs_put_request(rreq, was_async, netfs_rreq_trace_put_complete);
-}
-
-/*
- * Deal with the completion of writing the data to the cache. We have to clear
- * the PG_fscache bits on the folios involved and release the caller's ref.
- *
- * May be called in softirq mode and we inherit a ref from the caller.
- */
-static void netfs_rreq_unmark_after_write(struct netfs_io_request *rreq,
- bool was_async)
-{
- struct netfs_io_subrequest *subreq;
- struct folio *folio;
- pgoff_t unlocked = 0;
- bool have_unlocked = false;
-
- rcu_read_lock();
-
- list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
- XA_STATE(xas, &rreq->mapping->i_pages, subreq->start / PAGE_SIZE);
-
- xas_for_each(&xas, folio, (subreq->start + subreq->len - 1) / PAGE_SIZE) {
- /* We might have multiple writes from the same huge
- * folio, but we mustn't unlock a folio more than once.
- */
- if (have_unlocked && folio_index(folio) <= unlocked)
- continue;
- unlocked = folio_index(folio);
- folio_end_fscache(folio);
- have_unlocked = true;
- }
- }
-
- rcu_read_unlock();
- netfs_rreq_completed(rreq, was_async);
-}
-
-static void netfs_rreq_copy_terminated(void *priv, ssize_t transferred_or_error,
- bool was_async)
-{
- struct netfs_io_subrequest *subreq = priv;
- struct netfs_io_request *rreq = subreq->rreq;
-
- if (IS_ERR_VALUE(transferred_or_error)) {
- netfs_stat(&netfs_n_rh_write_failed);
- trace_netfs_failure(rreq, subreq, transferred_or_error,
- netfs_fail_copy_to_cache);
- } else {
- netfs_stat(&netfs_n_rh_write_done);
- }
-
- trace_netfs_sreq(subreq, netfs_sreq_trace_write_term);
-
- /* If we decrement nr_copy_ops to 0, the ref belongs to us. */
- if (atomic_dec_and_test(&rreq->nr_copy_ops))
- netfs_rreq_unmark_after_write(rreq, was_async);
-
- netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);
-}
-
-/*
- * Perform any outstanding writes to the cache. We inherit a ref from the
- * caller.
- */
-static void netfs_rreq_do_write_to_cache(struct netfs_io_request *rreq)
-{
- struct netfs_cache_resources *cres = &rreq->cache_resources;
- struct netfs_io_subrequest *subreq, *next, *p;
- struct iov_iter iter;
- int ret;
-
- trace_netfs_rreq(rreq, netfs_rreq_trace_copy);
-
- /* We don't want terminating writes trying to wake us up whilst we're
- * still going through the list.
- */
- atomic_inc(&rreq->nr_copy_ops);
-
- list_for_each_entry_safe(subreq, p, &rreq->subrequests, rreq_link) {
- if (!test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags)) {
- list_del_init(&subreq->rreq_link);
- netfs_put_subrequest(subreq, false,
- netfs_sreq_trace_put_no_copy);
- }
- }
-
- list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
- /* Amalgamate adjacent writes */
- while (!list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
- next = list_next_entry(subreq, rreq_link);
- if (next->start != subreq->start + subreq->len)
- break;
- subreq->len += next->len;
- list_del_init(&next->rreq_link);
- netfs_put_subrequest(next, false,
- netfs_sreq_trace_put_merged);
- }
-
- ret = cres->ops->prepare_write(cres, &subreq->start, &subreq->len,
- rreq->i_size, true);
- if (ret < 0) {
- trace_netfs_failure(rreq, subreq, ret, netfs_fail_prepare_write);
- trace_netfs_sreq(subreq, netfs_sreq_trace_write_skip);
- continue;
- }
-
- iov_iter_xarray(&iter, WRITE, &rreq->mapping->i_pages,
- subreq->start, subreq->len);
-
- atomic_inc(&rreq->nr_copy_ops);
- netfs_stat(&netfs_n_rh_write);
- netfs_get_subrequest(subreq, netfs_sreq_trace_get_copy_to_cache);
- trace_netfs_sreq(subreq, netfs_sreq_trace_write);
- cres->ops->write(cres, subreq->start, &iter,
- netfs_rreq_copy_terminated, subreq);
- }
-
- /* If we decrement nr_copy_ops to 0, the usage ref belongs to us. */
- if (atomic_dec_and_test(&rreq->nr_copy_ops))
- netfs_rreq_unmark_after_write(rreq, false);
-}
-
-static void netfs_rreq_write_to_cache_work(struct work_struct *work)
-{
- struct netfs_io_request *rreq =
- container_of(work, struct netfs_io_request, work);
-
- netfs_rreq_do_write_to_cache(rreq);
-}
-
-static void netfs_rreq_write_to_cache(struct netfs_io_request *rreq)
-{
- rreq->work.func = netfs_rreq_write_to_cache_work;
- if (!queue_work(system_unbound_wq, &rreq->work))
- BUG();
-}
-
-/*
- * Unlock the folios in a read operation. We need to set PG_fscache on any
- * folios we're going to write back before we unlock them.
- */
-void netfs_rreq_unlock_folios(struct netfs_io_request *rreq)
-{
- struct netfs_io_subrequest *subreq;
- struct folio *folio;
- unsigned int iopos, account = 0;
- pgoff_t start_page = rreq->start / PAGE_SIZE;
- pgoff_t last_page = ((rreq->start + rreq->len) / PAGE_SIZE) - 1;
- bool subreq_failed = false;
-
- XA_STATE(xas, &rreq->mapping->i_pages, start_page);
-
- if (test_bit(NETFS_RREQ_FAILED, &rreq->flags)) {
- __clear_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags);
- list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
- __clear_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags);
- }
- }
-
- /* Walk through the pagecache and the I/O request lists simultaneously.
- * We may have a mixture of cached and uncached sections and we only
- * really want to write out the uncached sections. This is slightly
- * complicated by the possibility that we might have huge pages with a
- * mixture inside.
- */
- subreq = list_first_entry(&rreq->subrequests,
- struct netfs_io_subrequest, rreq_link);
- iopos = 0;
- subreq_failed = (subreq->error < 0);
-
- trace_netfs_rreq(rreq, netfs_rreq_trace_unlock);
-
- rcu_read_lock();
- xas_for_each(&xas, folio, last_page) {
- unsigned int pgpos = (folio_index(folio) - start_page) * PAGE_SIZE;
- unsigned int pgend = pgpos + folio_size(folio);
- bool pg_failed = false;
-
- for (;;) {
- if (!subreq) {
- pg_failed = true;
- break;
- }
- if (test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags))
- folio_start_fscache(folio);
- pg_failed |= subreq_failed;
- if (pgend < iopos + subreq->len)
- break;
-
- account += subreq->transferred;
- iopos += subreq->len;
- if (!list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
- subreq = list_next_entry(subreq, rreq_link);
- subreq_failed = (subreq->error < 0);
- } else {
- subreq = NULL;
- subreq_failed = false;
- }
- if (pgend == iopos)
- break;
- }
-
- if (!pg_failed) {
- flush_dcache_folio(folio);
- folio_mark_uptodate(folio);
- }
-
- if (!test_bit(NETFS_RREQ_DONT_UNLOCK_FOLIOS, &rreq->flags)) {
- if (folio_index(folio) == rreq->no_unlock_folio &&
- test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags))
- _debug("no unlock");
- else
- folio_unlock(folio);
- }
- }
- rcu_read_unlock();
-
- task_io_account_read(account);
- if (rreq->netfs_ops->done)
- rreq->netfs_ops->done(rreq);
-}
-
-/*
- * Handle a short read.
- */
-static void netfs_rreq_short_read(struct netfs_io_request *rreq,
- struct netfs_io_subrequest *subreq)
-{
- __clear_bit(NETFS_SREQ_SHORT_IO, &subreq->flags);
- __set_bit(NETFS_SREQ_SEEK_DATA_READ, &subreq->flags);
-
- netfs_stat(&netfs_n_rh_short_read);
- trace_netfs_sreq(subreq, netfs_sreq_trace_resubmit_short);
-
- netfs_get_subrequest(subreq, netfs_sreq_trace_get_short_read);
- atomic_inc(&rreq->nr_outstanding);
- if (subreq->source == NETFS_READ_FROM_CACHE)
- netfs_read_from_cache(rreq, subreq, NETFS_READ_HOLE_CLEAR);
- else
- netfs_read_from_server(rreq, subreq);
-}
-
-/*
- * Resubmit any short or failed operations. Returns true if we got the rreq
- * ref back.
- */
-static bool netfs_rreq_perform_resubmissions(struct netfs_io_request *rreq)
-{
- struct netfs_io_subrequest *subreq;
-
- WARN_ON(in_interrupt());
-
- trace_netfs_rreq(rreq, netfs_rreq_trace_resubmit);
-
- /* We don't want terminating submissions trying to wake us up whilst
- * we're still going through the list.
- */
- atomic_inc(&rreq->nr_outstanding);
-
- __clear_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
- list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
- if (subreq->error) {
- if (subreq->source != NETFS_READ_FROM_CACHE)
- break;
- subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
- subreq->error = 0;
- netfs_stat(&netfs_n_rh_download_instead);
- trace_netfs_sreq(subreq, netfs_sreq_trace_download_instead);
- netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
- atomic_inc(&rreq->nr_outstanding);
- netfs_read_from_server(rreq, subreq);
- } else if (test_bit(NETFS_SREQ_SHORT_IO, &subreq->flags)) {
- netfs_rreq_short_read(rreq, subreq);
- }
- }
-
- /* If we decrement nr_outstanding to 0, the usage ref belongs to us. */
- if (atomic_dec_and_test(&rreq->nr_outstanding))
- return true;
-
- wake_up_var(&rreq->nr_outstanding);
- return false;
-}
-
-/*
- * Check to see if the data read is still valid.
- */
-static void netfs_rreq_is_still_valid(struct netfs_io_request *rreq)
-{
- struct netfs_io_subrequest *subreq;
-
- if (!rreq->netfs_ops->is_still_valid ||
- rreq->netfs_ops->is_still_valid(rreq))
- return;
-
- list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
- if (subreq->source == NETFS_READ_FROM_CACHE) {
- subreq->error = -ESTALE;
- __set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
- }
- }
-}
-
-/*
- * Assess the state of a read request and decide what to do next.
- *
- * Note that we could be in an ordinary kernel thread, on a workqueue or in
- * softirq context at this point. We inherit a ref from the caller.
- */
-static void netfs_rreq_assess(struct netfs_io_request *rreq, bool was_async)
-{
- trace_netfs_rreq(rreq, netfs_rreq_trace_assess);
-
-again:
- netfs_rreq_is_still_valid(rreq);
-
- if (!test_bit(NETFS_RREQ_FAILED, &rreq->flags) &&
- test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags)) {
- if (netfs_rreq_perform_resubmissions(rreq))
- goto again;
- return;
- }
-
- netfs_rreq_unlock_folios(rreq);
-
- clear_bit_unlock(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
- wake_up_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS);
-
- if (test_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags))
- return netfs_rreq_write_to_cache(rreq);
-
- netfs_rreq_completed(rreq, was_async);
-}
-
-static void netfs_rreq_work(struct work_struct *work)
-{
- struct netfs_io_request *rreq =
- container_of(work, struct netfs_io_request, work);
- netfs_rreq_assess(rreq, false);
-}
-
-/*
- * Handle the completion of all outstanding I/O operations on a read request.
- * We inherit a ref from the caller.
- */
-static void netfs_rreq_terminated(struct netfs_io_request *rreq,
- bool was_async)
-{
- if (test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags) &&
- was_async) {
- if (!queue_work(system_unbound_wq, &rreq->work))
- BUG();
- } else {
- netfs_rreq_assess(rreq, was_async);
- }
-}
-
-/**
- * netfs_subreq_terminated - Note the termination of an I/O operation.
- * @subreq: The I/O request that has terminated.
- * @transferred_or_error: The amount of data transferred or an error code.
- * @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 in @transferred_or_error the outcome of the operation,
- * supplying a positive value to indicate the number of bytes transferred, 0 to
- * indicate a failure to transfer anything that should be retried or a negative
- * error code. The helper will look after reissuing I/O operations as
- * appropriate and writing downloaded data to the cache.
- *
- * If @was_async is true, the caller might be running in softirq or interrupt
- * context and we can't sleep.
- */
-void netfs_subreq_terminated(struct netfs_io_subrequest *subreq,
- ssize_t transferred_or_error,
- bool was_async)
-{
- struct netfs_io_request *rreq = subreq->rreq;
- int u;
-
- _enter("[%u]{%llx,%lx},%zd",
- subreq->debug_index, subreq->start, subreq->flags,
- transferred_or_error);
-
- switch (subreq->source) {
- case NETFS_READ_FROM_CACHE:
- netfs_stat(&netfs_n_rh_read_done);
- break;
- case NETFS_DOWNLOAD_FROM_SERVER:
- netfs_stat(&netfs_n_rh_download_done);
- break;
- default:
- break;
- }
-
- if (IS_ERR_VALUE(transferred_or_error)) {
- subreq->error = transferred_or_error;
- trace_netfs_failure(rreq, subreq, transferred_or_error,
- netfs_fail_read);
- goto failed;
- }
-
- if (WARN(transferred_or_error > subreq->len - subreq->transferred,
- "Subreq overread: R%x[%x] %zd > %zu - %zu",
- rreq->debug_id, subreq->debug_index,
- transferred_or_error, subreq->len, subreq->transferred))
- transferred_or_error = subreq->len - subreq->transferred;
-
- subreq->error = 0;
- subreq->transferred += transferred_or_error;
- if (subreq->transferred < subreq->len)
- goto incomplete;
-
-complete:
- __clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
- if (test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags))
- set_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags);
-
-out:
- trace_netfs_sreq(subreq, netfs_sreq_trace_terminated);
-
- /* If we decrement nr_outstanding to 0, the ref belongs to us. */
- u = atomic_dec_return(&rreq->nr_outstanding);
- if (u == 0)
- netfs_rreq_terminated(rreq, was_async);
- else if (u == 1)
- wake_up_var(&rreq->nr_outstanding);
-
- netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);
- return;
-
-incomplete:
- if (test_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags)) {
- netfs_clear_unread(subreq);
- subreq->transferred = subreq->len;
- goto complete;
- }
-
- if (transferred_or_error == 0) {
- if (__test_and_set_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags)) {
- subreq->error = -ENODATA;
- goto failed;
- }
- } else {
- __clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
- }
-
- __set_bit(NETFS_SREQ_SHORT_IO, &subreq->flags);
- set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
- goto out;
-
-failed:
- if (subreq->source == NETFS_READ_FROM_CACHE) {
- netfs_stat(&netfs_n_rh_read_failed);
- set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
- } else {
- netfs_stat(&netfs_n_rh_download_failed);
- set_bit(NETFS_RREQ_FAILED, &rreq->flags);
- rreq->error = subreq->error;
- }
- goto out;
-}
-EXPORT_SYMBOL(netfs_subreq_terminated);
-
-static enum netfs_io_source netfs_cache_prepare_read(struct netfs_io_subrequest *subreq,
- loff_t i_size)
-{
- struct netfs_io_request *rreq = subreq->rreq;
- struct netfs_cache_resources *cres = &rreq->cache_resources;
-
- if (cres->ops)
- return cres->ops->prepare_read(subreq, i_size);
- if (subreq->start >= rreq->i_size)
- return NETFS_FILL_WITH_ZEROES;
- return NETFS_DOWNLOAD_FROM_SERVER;
-}
-
-/*
- * Work out what sort of subrequest the next one will be.
- */
-static enum netfs_io_source
-netfs_rreq_prepare_read(struct netfs_io_request *rreq,
- struct netfs_io_subrequest *subreq)
-{
- enum netfs_io_source source;
-
- _enter("%llx-%llx,%llx", subreq->start, subreq->start + subreq->len, rreq->i_size);
-
- source = netfs_cache_prepare_read(subreq, rreq->i_size);
- if (source == NETFS_INVALID_READ)
- goto out;
-
- if (source == NETFS_DOWNLOAD_FROM_SERVER) {
- /* Call out to the netfs to let it shrink the request to fit
- * its own I/O sizes and boundaries. If it shinks it here, it
- * will be called again to make simultaneous calls; if it wants
- * to make serial calls, it can indicate a short read and then
- * we will call it again.
- */
- if (subreq->len > rreq->i_size - subreq->start)
- subreq->len = rreq->i_size - subreq->start;
-
- if (rreq->netfs_ops->clamp_length &&
- !rreq->netfs_ops->clamp_length(subreq)) {
- source = NETFS_INVALID_READ;
- goto out;
- }
- }
-
- if (WARN_ON(subreq->len == 0))
- source = NETFS_INVALID_READ;
-
-out:
- subreq->source = source;
- trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
- return source;
-}
-
-/*
- * Slice off a piece of a read request and submit an I/O request for it.
- */
-static bool netfs_rreq_submit_slice(struct netfs_io_request *rreq,
- unsigned int *_debug_index)
-{
- struct netfs_io_subrequest *subreq;
- enum netfs_io_source source;
-
- subreq = netfs_alloc_subrequest(rreq);
- if (!subreq)
- return false;
-
- subreq->debug_index = (*_debug_index)++;
- subreq->start = rreq->start + rreq->submitted;
- subreq->len = rreq->len - rreq->submitted;
-
- _debug("slice %llx,%zx,%zx", subreq->start, subreq->len, rreq->submitted);
- list_add_tail(&subreq->rreq_link, &rreq->subrequests);
-
- /* Call out to the cache to find out what it can do with the remaining
- * subset. It tells us in subreq->flags what it decided should be done
- * and adjusts subreq->len down if the subset crosses a cache boundary.
- *
- * Then when we hand the subset, it can choose to take a subset of that
- * (the starts must coincide), in which case, we go around the loop
- * again and ask it to download the next piece.
- */
- source = netfs_rreq_prepare_read(rreq, subreq);
- if (source == NETFS_INVALID_READ)
- goto subreq_failed;
-
- atomic_inc(&rreq->nr_outstanding);
-
- rreq->submitted += subreq->len;
-
- trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
- switch (source) {
- case NETFS_FILL_WITH_ZEROES:
- netfs_fill_with_zeroes(rreq, subreq);
- break;
- case NETFS_DOWNLOAD_FROM_SERVER:
- netfs_read_from_server(rreq, subreq);
- break;
- case NETFS_READ_FROM_CACHE:
- netfs_read_from_cache(rreq, subreq, NETFS_READ_HOLE_IGNORE);
- break;
- default:
- BUG();
- }
-
- return true;
-
-subreq_failed:
- rreq->error = subreq->error;
- netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_failed);
- return false;
-}
-
-/*
- * Begin the process of reading in a chunk of data, where that data may be
- * stitched together from multiple sources, including multiple servers and the
- * local cache.
- */
-int netfs_begin_read(struct netfs_io_request *rreq, bool sync)
-{
- unsigned int debug_index = 0;
- int ret;
-
- _enter("R=%x %llx-%llx",
- rreq->debug_id, rreq->start, rreq->start + rreq->len - 1);
-
- if (rreq->len == 0) {
- pr_err("Zero-sized read [R=%x]\n", rreq->debug_id);
- netfs_put_request(rreq, false, netfs_rreq_trace_put_zero_len);
- return -EIO;
- }
-
- INIT_WORK(&rreq->work, netfs_rreq_work);
-
- if (sync)
- netfs_get_request(rreq, netfs_rreq_trace_get_hold);
-
- /* Chop the read into slices according to what the cache and the netfs
- * want and submit each one.
- */
- atomic_set(&rreq->nr_outstanding, 1);
- do {
- if (!netfs_rreq_submit_slice(rreq, &debug_index))
- break;
-
- } while (rreq->submitted < rreq->len);
-
- if (sync) {
- /* Keep nr_outstanding incremented so that the ref always belongs to
- * us, and the service code isn't punted off to a random thread pool to
- * process.
- */
- for (;;) {
- wait_var_event(&rreq->nr_outstanding,
- atomic_read(&rreq->nr_outstanding) == 1);
- netfs_rreq_assess(rreq, false);
- if (!test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags))
- break;
- cond_resched();
- }
-
- ret = rreq->error;
- if (ret == 0 && rreq->submitted < rreq->len) {
- trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_read);
- ret = -EIO;
- }
- netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);
- } else {
- /* If we decrement nr_outstanding to 0, the ref belongs to us. */
- if (atomic_dec_and_test(&rreq->nr_outstanding))
- netfs_rreq_assess(rreq, false);
- ret = 0;
- }
- return ret;
-}
-
-static void netfs_cache_expand_readahead(struct netfs_io_request *rreq,
- loff_t *_start, size_t *_len, loff_t i_size)
-{
- struct netfs_cache_resources *cres = &rreq->cache_resources;
-
- if (cres->ops && cres->ops->expand_readahead)
- cres->ops->expand_readahead(cres, _start, _len, i_size);
-}
-
-static void netfs_rreq_expand(struct netfs_io_request *rreq,
- struct readahead_control *ractl)
-{
- /* Give the cache a chance to change the request parameters. The
- * resultant request must contain the original region.
- */
- netfs_cache_expand_readahead(rreq, &rreq->start, &rreq->len, rreq->i_size);
-
- /* Give the netfs a chance to change the request parameters. The
- * resultant request must contain the original region.
- */
- if (rreq->netfs_ops->expand_readahead)
- rreq->netfs_ops->expand_readahead(rreq);
-
- /* Expand the request if the cache wants it to start earlier. Note
- * that the expansion may get further extended if the VM wishes to
- * insert THPs and the preferred start and/or end wind up in the middle
- * of THPs.
- *
- * If this is the case, however, the THP size should be an integer
- * multiple of the cache granule size, so we get a whole number of
- * granules to deal with.
- */
- if (rreq->start != readahead_pos(ractl) ||
- rreq->len != readahead_length(ractl)) {
- readahead_expand(ractl, rreq->start, rreq->len);
- rreq->start = readahead_pos(ractl);
- rreq->len = readahead_length(ractl);
-
- trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
- netfs_read_trace_expanded);
- }
-}
-
-/**
- * netfs_readahead - Helper to manage a read request
- * @ractl: The description of the readahead request
- *
- * Fulfil a readahead request by drawing data from the cache if possible, or
- * the netfs if not. Space beyond the EOF is zero-filled. Multiple I/O
- * requests from different sources will get munged together. If necessary, the
- * readahead window can be expanded in either direction to a more convenient
- * alighment for RPC efficiency or to make storage in the cache feasible.
- *
- * 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.
- */
-void netfs_readahead(struct readahead_control *ractl)
-{
- struct netfs_io_request *rreq;
- struct netfs_i_context *ctx = netfs_i_context(ractl->mapping->host);
- int ret;
-
- _enter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
-
- if (readahead_count(ractl) == 0)
- return;
-
- rreq = netfs_alloc_request(ractl->mapping, ractl->file,
- readahead_pos(ractl),
- readahead_length(ractl),
- NETFS_READAHEAD);
- if (IS_ERR(rreq))
- return;
-
- if (ctx->ops->begin_cache_operation) {
- ret = ctx->ops->begin_cache_operation(rreq);
- if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
- goto cleanup_free;
- }
-
- netfs_stat(&netfs_n_rh_readahead);
- trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
- netfs_read_trace_readahead);
-
- netfs_rreq_expand(rreq, ractl);
-
- /* Drop the refs on the folios here rather than in the cache or
- * filesystem. The locks will be dropped in netfs_rreq_unlock().
- */
- while (readahead_folio(ractl))
- ;
-
- netfs_begin_read(rreq, false);
- return;
-
-cleanup_free:
- netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
- return;
-}
-EXPORT_SYMBOL(netfs_readahead);
-
-/**
- * netfs_readpage - Helper to manage a readpage request
- * @file: The file to read from
- * @subpage: A subpage of the folio to read
- *
- * Fulfil a readpage request by drawing data from the cache if possible, or the
- * netfs if not. Space beyond the EOF is zero-filled. Multiple I/O requests
- * from different sources will get munged together.
- *
- * 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.
- */
-int netfs_readpage(struct file *file, struct page *subpage)
-{
- struct folio *folio = page_folio(subpage);
- struct address_space *mapping = folio->mapping;
- struct netfs_io_request *rreq;
- struct netfs_i_context *ctx = netfs_i_context(mapping->host);
- int ret;
-
- _enter("%lx", folio_index(folio));
-
- rreq = netfs_alloc_request(mapping, file,
- folio_file_pos(folio), folio_size(folio),
- NETFS_READPAGE);
- if (IS_ERR(rreq)) {
- ret = PTR_ERR(rreq);
- goto alloc_error;
- }
-
- if (ctx->ops->begin_cache_operation) {
- ret = ctx->ops->begin_cache_operation(rreq);
- if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
- goto discard;
- }
-
- netfs_stat(&netfs_n_rh_readpage);
- trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
- return netfs_begin_read(rreq, true);
-
-discard:
- netfs_put_request(rreq, false, netfs_rreq_trace_put_discard);
-alloc_error:
- folio_unlock(folio);
- return ret;
-}
-EXPORT_SYMBOL(netfs_readpage);
-
-/*
- * Prepare a folio for writing without reading first
- * @folio: The folio being prepared
- * @pos: starting position for the write
- * @len: length of write
- * @always_fill: T if the folio should always be completely filled/cleared
- *
- * In some cases, write_begin doesn't need to read at all:
- * - full folio write
- * - write that lies in a folio that is completely beyond EOF
- * - write that covers the folio from start to EOF or beyond it
- *
- * If any of these criteria are met, then zero out the unwritten parts
- * of the folio and return true. Otherwise, return false.
- */
-static bool netfs_skip_folio_read(struct folio *folio, loff_t pos, size_t len,
- bool always_fill)
-{
- struct inode *inode = folio_inode(folio);
- loff_t i_size = i_size_read(inode);
- size_t offset = offset_in_folio(folio, pos);
- size_t plen = folio_size(folio);
-
- if (unlikely(always_fill)) {
- if (pos - offset + len <= i_size)
- return false; /* Page entirely before EOF */
- zero_user_segment(&folio->page, 0, plen);
- folio_mark_uptodate(folio);
- return true;
- }
-
- /* Full folio write */
- if (offset == 0 && len >= plen)
- return true;
-
- /* Page entirely beyond the end of the file */
- if (pos - offset >= i_size)
- goto zero_out;
-
- /* Write that covers from the start of the folio to EOF or beyond */
- if (offset == 0 && (pos + len) >= i_size)
- goto zero_out;
-
- return false;
-zero_out:
- zero_user_segments(&folio->page, 0, offset, offset + len, len);
- return true;
-}
-
-/**
- * netfs_write_begin - Helper to prepare for writing
- * @file: The file to read from
- * @mapping: The mapping to read from
- * @pos: File position at which the write will begin
- * @len: The length of the write (may extend beyond the end of the folio chosen)
- * @aop_flags: AOP_* flags
- * @_folio: Where to put the resultant folio
- * @_fsdata: Place for the netfs to store a cookie
- *
- * Pre-read data for a write-begin request by drawing data from the cache if
- * possible, or the netfs if not. Space beyond the EOF is zero-filled.
- * Multiple I/O requests from different sources will get munged together. If
- * necessary, the readahead window can be expanded in either direction to a
- * more convenient alighment for RPC efficiency or to make storage in the cache
- * feasible.
- *
- * The calling netfs must provide a table of operations, only one of which,
- * issue_op, is mandatory.
- *
- * The check_write_begin() operation can be provided to check for and flush
- * conflicting writes once the folio is grabbed and locked. It is passed a
- * pointer to the fsdata cookie that gets returned to the VM to be passed to
- * write_end. It is permitted to sleep. It should return 0 if the request
- * should go ahead; unlock the folio and return -EAGAIN to cause the folio to
- * be regot; or return an error.
- *
- * 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.
- */
-int netfs_write_begin(struct file *file, struct address_space *mapping,
- loff_t pos, unsigned int len, unsigned int aop_flags,
- struct folio **_folio, void **_fsdata)
-{
- struct netfs_io_request *rreq;
- struct netfs_i_context *ctx = netfs_i_context(file_inode(file ));
- struct folio *folio;
- unsigned int fgp_flags;
- pgoff_t index = pos >> PAGE_SHIFT;
- int ret;
-
- DEFINE_READAHEAD(ractl, file, NULL, mapping, index);
-
-retry:
- fgp_flags = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE;
- if (aop_flags & AOP_FLAG_NOFS)
- fgp_flags |= FGP_NOFS;
- folio = __filemap_get_folio(mapping, index, fgp_flags,
- mapping_gfp_mask(mapping));
- if (!folio)
- return -ENOMEM;
-
- if (ctx->ops->check_write_begin) {
- /* Allow the netfs (eg. ceph) to flush conflicts. */
- ret = ctx->ops->check_write_begin(file, pos, len, folio, _fsdata);
- if (ret < 0) {
- trace_netfs_failure(NULL, NULL, ret, netfs_fail_check_write_begin);
- if (ret == -EAGAIN)
- goto retry;
- goto error;
- }
- }
-
- if (folio_test_uptodate(folio))
- goto have_folio;
-
- /* If the page is beyond the EOF, we want to clear it - unless it's
- * within the cache granule containing the EOF, in which case we need
- * to preload the granule.
- */
- if (!netfs_is_cache_enabled(ctx) &&
- netfs_skip_folio_read(folio, pos, len, false)) {
- netfs_stat(&netfs_n_rh_write_zskip);
- goto have_folio_no_wait;
- }
-
- rreq = netfs_alloc_request(mapping, file,
- folio_file_pos(folio), folio_size(folio),
- NETFS_READ_FOR_WRITE);
- if (IS_ERR(rreq)) {
- ret = PTR_ERR(rreq);
- goto error;
- }
- rreq->no_unlock_folio = folio_index(folio);
- __set_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags);
-
- if (ctx->ops->begin_cache_operation) {
- ret = ctx->ops->begin_cache_operation(rreq);
- if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
- goto error_put;
- }
-
- netfs_stat(&netfs_n_rh_write_begin);
- trace_netfs_read(rreq, pos, len, netfs_read_trace_write_begin);
-
- /* Expand the request to meet caching requirements and download
- * preferences.
- */
- ractl._nr_pages = folio_nr_pages(folio);
- netfs_rreq_expand(rreq, &ractl);
-
- /* We hold the folio locks, so we can drop the references */
- folio_get(folio);
- while (readahead_folio(&ractl))
- ;
-
- ret = netfs_begin_read(rreq, true);
- if (ret < 0)
- goto error;
-
-have_folio:
- ret = folio_wait_fscache_killable(folio);
- if (ret < 0)
- goto error;
-have_folio_no_wait:
- *_folio = folio;
- _leave(" = 0");
- return 0;
-
-error_put:
- netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
-error:
- folio_unlock(folio);
- folio_put(folio);
- _leave(" = %d", ret);
- return ret;
-}
-EXPORT_SYMBOL(netfs_write_begin);
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