The read_helper.c file now only contains I/O functions, so rename the file
to io.c. It will eventually get write-side I/O functions also.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: linux-cachefs@xxxxxxxxxx
---
fs/netfs/Makefile | 4
fs/netfs/internal.h | 10 -
fs/netfs/io.c | 656 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/netfs/read_helper.c | 656 ------------------------------------------------
4 files changed, 663 insertions(+), 663 deletions(-)
create mode 100644 fs/netfs/io.c
delete mode 100644 fs/netfs/read_helper.c
diff --git a/fs/netfs/Makefile b/fs/netfs/Makefile
index 029657b6db63..f684c0cd1ec5 100644
--- a/fs/netfs/Makefile
+++ b/fs/netfs/Makefile
@@ -2,9 +2,9 @@
netfs-y := \
buffered_read.o \
+ io.o \
main.o \
- objects.o \
- read_helper.o
+ objects.o
netfs-$(CONFIG_NETFS_STATS) += stats.o
diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index f9dd64521fe6..e2c80b10bf4d 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -20,6 +20,11 @@
*/
void netfs_rreq_unlock_folios(struct netfs_io_request *rreq);
+/*
+ * io.c
+ */
+int netfs_begin_read(struct netfs_io_request *rreq, bool sync);
+
/*
* main.c
*/
@@ -44,11 +49,6 @@ 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
- */
-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..3db9356eb7c2
--- /dev/null
+++ b/fs/netfs/io.c
@@ -0,0 +1,656 @@
+// 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@xxxxxxxxxx)
+ */
+
+#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"
+
+/*
+ * 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();
+}
+
+/*
+ * 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;
+ }
+
+ rreq->work.func = 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);
+ }
+ return ret;
+}
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
deleted file mode 100644
index 3db9356eb7c2..000000000000
--- a/fs/netfs/read_helper.c
+++ /dev/null
@@ -1,656 +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@xxxxxxxxxx)
- */
-
-#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"
-
-/*
- * 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();
-}
-
-/*
- * 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;
- }
-
- rreq->work.func = 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);
- }
- return ret;
-}
--
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