From patchwork Mon Jul 29 16:19:48 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13745439 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7D71619048E for ; Mon, 29 Jul 2024 16:22:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722270164; cv=none; b=GWzT5zoAWq89BgMsMoBLKwF2MYBTvwVP5za85AoJO6A6+rjg3KcrtF8YjrdUAh99C23SmbCaPdz3ZEiqLWUwMtMa3PB0Nh6nJthNJWMkttywW15DoG5VL5RWPgQIY1q3Xo60x9HCDI0FsxmSjpQdw4+aadOH5LQDLrkx/ZZDslE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722270164; c=relaxed/simple; bh=K4EJv8NWKCLLHqikGqf17QKGhd+c/FIaP7KDLNYCsSE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KA+2ZxcsGiqQeNS7F/Ofh2uPcd6tEPjsXFHC9yy7g86EOvQevdVLORdZQFh/PJQYX8H0mVRToqPq5A+upJd7ipLHt3MVCtT5OLYITBa01hZCAc557IX1KzM+USIVrbkG0C3yW6v+HCyBy2CZNOh5I3AwYWF8FvJ8XQszESmzROg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=HdLyrIC6; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HdLyrIC6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722270161; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1pcIqRM16ak+E/K4Jv6V7A/QZpCDC8qVvLvriALKmTg=; b=HdLyrIC6mJX6HmVH9lhEqCWt0Wtj5MHZ8f/geYjO9/Lyuy7IXdKJKrBj1iHeAnxDDHhEKo AAqftZsSkpmEhGOcK6Ek1vGTQrzDBwgrf22Wwg0KT8bt4uutBpJL7qcvoEvChF2yKcp9uJ qREc5mZ0V/l0l78zkJVNPoHmiBFKgkI= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-37-r7_A47KWOHqfQhKyoWqh9Q-1; Mon, 29 Jul 2024 12:22:38 -0400 X-MC-Unique: r7_A47KWOHqfQhKyoWqh9Q-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 471EC1955EA1; Mon, 29 Jul 2024 16:22:35 +0000 (UTC) Received: from warthog.procyon.org.uk.com (unknown [10.42.28.216]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 46AA51955D48; Mon, 29 Jul 2024 16:22:29 +0000 (UTC) From: David Howells To: Christian Brauner , Steve French , Matthew Wilcox Cc: David Howells , Jeff Layton , Gao Xiang , Dominique Martinet , Marc Dionne , Paulo Alcantara , Shyam Prasad N , Tom Talpey , Eric Van Hensbergen , Ilya Dryomov , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 19/24] netfs: Remove fs/netfs/io.c Date: Mon, 29 Jul 2024 17:19:48 +0100 Message-ID: <20240729162002.3436763-20-dhowells@redhat.com> In-Reply-To: <20240729162002.3436763-1-dhowells@redhat.com> References: <20240729162002.3436763-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Remove fs/netfs/io.c as it is no longer used. Signed-off-by: David Howells cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org --- fs/netfs/io.c | 645 -------------------------------------------------- 1 file changed, 645 deletions(-) delete mode 100644 fs/netfs/io.c diff --git a/fs/netfs/io.c b/fs/netfs/io.c deleted file mode 100644 index 874bbf2386a4..000000000000 --- a/fs/netfs/io.c +++ /dev/null @@ -1,645 +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@redhat.com) - */ - -#include -#include -#include -#include -#include -#include -#include -#include -#include -#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); -} - -/* - * 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; - 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)) { - 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) - 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); - - 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) - 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, - 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; - } - 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 (rreq->origin == NETFS_DIO_READ && - rreq->start + rreq->submitted >= rreq->i_size) - break; - if (!netfs_rreq_submit_slice(rreq, &io_iter)) - 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 && rreq->submitted < rreq->len && - rreq->origin != NETFS_DIO_READ) { - 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; -}