+++ /dev/null
-// 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@redhat.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"
-
-/*
- * Clear the unread part of an I/O request.
- */
-static void netfs_clear_unread(struct netfs_io_subrequest *subreq)
-{
- iov_iter_zero(iov_iter_count(&subreq->io_iter), &subreq->io_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;
-
- netfs_stat(&netfs_n_rh_read);
- cres->ops->read(cres, subreq->start, &subreq->io_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);
-
- if (rreq->origin != NETFS_DIO_READ &&
- iov_iter_count(&subreq->io_iter) != subreq->len - subreq->transferred)
- pr_warn("R=%08x[%u] ITER PRE-MISMATCH %zx != %zx-%zx %lx\n",
- rreq->debug_id, subreq->debug_index,
- iov_iter_count(&subreq->io_iter), subreq->len,
- subreq->transferred, subreq->flags);
- 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);
-}
-
-/*
- * [DEPRECATED] 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) {
- if (xas_retry(&xas, folio))
- continue;
-
- /* 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 <= unlocked)
- continue;
- unlocked = folio_next_index(folio) - 1;
- trace_netfs_folio(folio, netfs_folio_trace_end_copy);
- folio_end_private_2(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) /* [DEPRECATED] */
-{
- 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);
-}
-
-/*
- * [DEPRECATED] 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,
- 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, ITER_SOURCE, &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) /* [DEPRECATED] */
-{
- 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) /* [DEPRECATED] */
-{
- 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);
-}
-
-/*
- * Reset the subrequest iterator prior to resubmission.
- */
-static void netfs_reset_subreq_iter(struct netfs_io_request *rreq,
- struct netfs_io_subrequest *subreq)
-{
- size_t remaining = subreq->len - subreq->transferred;
- size_t count = iov_iter_count(&subreq->io_iter);
-
- if (count == remaining)
- return;
-
- _debug("R=%08x[%u] ITER RESUB-MISMATCH %zx != %zx-%zx-%llx %x\n",
- rreq->debug_id, subreq->debug_index,
- iov_iter_count(&subreq->io_iter), subreq->transferred,
- subreq->len, rreq->i_size,
- subreq->io_iter.iter_type);
-
- if (count < remaining)
- iov_iter_revert(&subreq->io_iter, remaining - count);
- else
- iov_iter_advance(&subreq->io_iter, count - remaining);
-}
-
-/*
- * 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;
- __set_bit(NETFS_SREQ_RETRYING, &subreq->flags);
- 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_reset_subreq_iter(rreq, subreq);
- netfs_read_from_server(rreq, subreq);
- } else if (test_bit(NETFS_SREQ_SHORT_IO, &subreq->flags)) {
- __set_bit(NETFS_SREQ_RETRYING, &subreq->flags);
- netfs_reset_subreq_iter(rreq, subreq);
- 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);
- }
- }
-}
-
-/*
- * Determine how much we can admit to having read from a DIO read.
- */
-static void netfs_rreq_assess_dio(struct netfs_io_request *rreq)
-{
- struct netfs_io_subrequest *subreq;
- unsigned int i;
- size_t transferred = 0;
-
- for (i = 0; i < rreq->direct_bv_count; i++) {
- flush_dcache_page(rreq->direct_bv[i].bv_page);
- // TODO: cifs marks pages in the destination buffer
- // dirty under some circumstances after a read. Do we
- // need to do that too?
- set_page_dirty(rreq->direct_bv[i].bv_page);
- }
-
- list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
- if (subreq->error || subreq->transferred == 0)
- break;
- transferred += subreq->transferred;
- if (subreq->transferred < subreq->len ||
- test_bit(NETFS_SREQ_HIT_EOF, &subreq->flags))
- break;
- }
-
- for (i = 0; i < rreq->direct_bv_count; i++)
- flush_dcache_page(rreq->direct_bv[i].bv_page);
-
- rreq->transferred = transferred;
- task_io_account_read(transferred);
-
- if (rreq->iocb) {
- rreq->iocb->ki_pos += transferred;
- if (rreq->iocb->ki_complete)
- rreq->iocb->ki_complete(
- rreq->iocb, rreq->error ? rreq->error : transferred);
- }
- if (rreq->netfs_ops->done)
- rreq->netfs_ops->done(rreq);
- inode_dio_end(rreq->inode);
-}
-
-/*
- * 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;
- }
-
- if (rreq->origin != NETFS_DIO_READ)
- netfs_rreq_unlock_folios(rreq);
- else
- netfs_rreq_assess_dio(rreq);
-
- trace_netfs_rreq(rreq, netfs_rreq_trace_wake_ip);
- 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) &&
- test_bit(NETFS_RREQ_USE_PGPRIV2, &rreq->flags))
- return netfs_rreq_write_to_cache(rreq);
-
- netfs_rreq_completed(rreq, was_async);
-}
-
-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("R=%x[%x]{%llx,%lx},%zd",
- rreq->debug_id, 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 &&
- !test_bit(NETFS_SREQ_HIT_EOF, &subreq->flags))
- 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)) {
- if (rreq->origin != NETFS_DIO_READ)
- 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,
- struct iov_iter *io_iter)
-{
- enum netfs_io_source source = NETFS_DOWNLOAD_FROM_SERVER;
- struct netfs_inode *ictx = netfs_inode(rreq->inode);
- size_t lsize;
-
- _enter("%llx-%llx,%llx", subreq->start, subreq->start + subreq->len, rreq->i_size);
-
- if (rreq->origin != NETFS_DIO_READ) {
- 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 (rreq->origin != NETFS_DIO_READ) {
- if (subreq->start >= ictx->zero_point) {
- source = NETFS_FILL_WITH_ZEROES;
- goto set;
- }
- if (subreq->len > ictx->zero_point - subreq->start)
- subreq->len = ictx->zero_point - subreq->start;
-
- /* We limit buffered reads to the EOF, but let the
- * server deal with larger-than-EOF DIO/unbuffered
- * reads.
- */
- if (subreq->len > rreq->i_size - subreq->start)
- subreq->len = rreq->i_size - subreq->start;
- }
- if (rreq->rsize && subreq->len > rreq->rsize)
- subreq->len = rreq->rsize;
-
- if (rreq->netfs_ops->clamp_length &&
- !rreq->netfs_ops->clamp_length(subreq)) {
- source = NETFS_INVALID_READ;
- goto out;
- }
-
- if (rreq->io_streams[0].sreq_max_segs) {
- lsize = netfs_limit_iter(io_iter, 0, subreq->len,
- rreq->io_streams[0].sreq_max_segs);
- if (subreq->len > lsize) {
- subreq->len = lsize;
- trace_netfs_sreq(subreq, netfs_sreq_trace_limited);
- }
- }
- }
-
-set:
- if (subreq->len > rreq->len)
- pr_warn("R=%08x[%u] SREQ>RREQ %zx > %llx\n",
- rreq->debug_id, subreq->debug_index,
- subreq->len, rreq->len);
-
- if (WARN_ON(subreq->len == 0)) {
- source = NETFS_INVALID_READ;
- goto out;
- }
-
- subreq->source = source;
- trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
-
- subreq->io_iter = *io_iter;
- iov_iter_truncate(&subreq->io_iter, subreq->len);
- iov_iter_advance(io_iter, subreq->len);
-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,
- struct iov_iter *io_iter)
-{
- struct netfs_io_subrequest *subreq;
- enum netfs_io_source source;
-
- subreq = netfs_alloc_subrequest(rreq);
- if (!subreq)
- return false;
-
- subreq->start = rreq->start + rreq->submitted;
- subreq->len = io_iter->count;
-
- _debug("slice %llx,%zx,%llx", 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, io_iter);
- 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)
-{
- struct iov_iter io_iter;
- 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);
- return -EIO;
- }
-
- if (rreq->origin == NETFS_DIO_READ)
- inode_dio_begin(rreq->inode);
-
- // TODO: Use bounce buffer if requested
- rreq->io_iter = rreq->iter;
-
- /* Chop the read into slices according to what the cache and the netfs
- * want and submit each one.
- */
- netfs_get_request(rreq, netfs_rreq_trace_get_for_outstanding);
- atomic_set(&rreq->nr_outstanding, 1);
- io_iter = rreq->io_iter;
- do {
- _debug("submit %llx + %llx >= %llx",
- rreq->start, rreq->submitted, rreq->i_size);
- if (!netfs_rreq_submit_slice(rreq, &io_iter))
- break;
- if (test_bit(NETFS_SREQ_NO_PROGRESS, &rreq->flags))
- break;
- if (test_bit(NETFS_RREQ_BLOCKED, &rreq->flags) &&
- test_bit(NETFS_RREQ_NONBLOCK, &rreq->flags))
- break;
-
- } while (rreq->submitted < rreq->len);
-
- if (!rreq->submitted) {
- netfs_put_request(rreq, false, netfs_rreq_trace_put_no_submit);
- if (rreq->origin == NETFS_DIO_READ)
- inode_dio_end(rreq->inode);
- ret = 0;
- goto out;
- }
-
- 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. Note that this might start
- * further work, such as writing to the cache.
- */
- wait_var_event(&rreq->nr_outstanding,
- atomic_read(&rreq->nr_outstanding) == 1);
- if (atomic_dec_and_test(&rreq->nr_outstanding))
- netfs_rreq_assess(rreq, false);
-
- trace_netfs_rreq(rreq, netfs_rreq_trace_wait_ip);
- wait_on_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS,
- TASK_UNINTERRUPTIBLE);
-
- ret = rreq->error;
- if (ret == 0) {
- if (rreq->origin == NETFS_DIO_READ) {
- ret = rreq->transferred;
- } else if (rreq->submitted < rreq->len) {
- trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_read);
- ret = -EIO;
- }
- }
- } 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 = -EIOCBQUEUED;
- }
-
-out:
- return ret;
-}
projects / thirdparty / kernel / linux.git / commitdiff
