From patchwork Fri Oct 13 16:03:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13421217 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C76EDCDB483 for ; Fri, 13 Oct 2023 16:07:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232684AbjJMQHx (ORCPT ); Fri, 13 Oct 2023 12:07:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47656 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233098AbjJMQG5 (ORCPT ); Fri, 13 Oct 2023 12:06:57 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 402ABD8 for ; Fri, 13 Oct 2023 09:05:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1697213146; 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=H+1i5F1S+6wxwGtTBxUYE1F0fETWm68EZav8/D9/C4o=; b=XA4Qek3vLjXre+gpNMZqxNagN5/ot5xyypLjFtzaAKITg4UyK03Qxk5UFpbhOLBt07uAU+ 4cuGCVplSRo80ERNXRTbhd9nSsOcedz4wznv58PyxyfJuLEucAX0mktR82o/0suP6maz8N vlkTkALoEfSFaRkAWBdragrhmKMyXXg= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-48-CiGEkiPFOyWFt3PkgwJsGg-1; Fri, 13 Oct 2023 12:05:43 -0400 X-MC-Unique: CiGEkiPFOyWFt3PkgwJsGg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E7945280FEC5; Fri, 13 Oct 2023 16:05:41 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.226]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6C8361C060DF; Fri, 13 Oct 2023 16:05:39 +0000 (UTC) From: David Howells To: Jeff Layton , Steve French Cc: David Howells , Matthew Wilcox , Marc Dionne , Paulo Alcantara , Shyam Prasad N , Tom Talpey , Dominique Martinet , Ilya Dryomov , Christian Brauner , 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-fsdevel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-cachefs@redhat.com Subject: [RFC PATCH 21/53] netfs: Make the refcounting of netfs_begin_read() easier to use Date: Fri, 13 Oct 2023 17:03:50 +0100 Message-ID: <20231013160423.2218093-22-dhowells@redhat.com> In-Reply-To: <20231013160423.2218093-1-dhowells@redhat.com> References: <20231013160423.2218093-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org Make the refcounting of netfs_begin_read() easier to use by not eating the caller's ref on the netfs_io_request it's given. This makes it easier to use when we need to look in the request struct after. Signed-off-by: David Howells cc: Jeff Layton cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org --- fs/netfs/buffered_read.c | 6 +++++- fs/netfs/io.c | 28 +++++++++++++--------------- include/trace/events/netfs.h | 9 +++++---- 3 files changed, 23 insertions(+), 20 deletions(-) diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index 3b7eb706f2fe..05824f73cfc7 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -217,6 +217,7 @@ void netfs_readahead(struct readahead_control *ractl) ; netfs_begin_read(rreq, false); + netfs_put_request(rreq, false, netfs_rreq_trace_put_return); return; cleanup_free: @@ -267,7 +268,9 @@ int netfs_read_folio(struct file *file, struct folio *folio) iov_iter_xarray(&rreq->iter, ITER_DEST, &mapping->i_pages, rreq->start, rreq->len); - return netfs_begin_read(rreq, true); + ret = netfs_begin_read(rreq, true); + netfs_put_request(rreq, false, netfs_rreq_trace_put_return); + return ret; discard: netfs_put_request(rreq, false, netfs_rreq_trace_put_discard); @@ -436,6 +439,7 @@ int netfs_write_begin(struct netfs_inode *ctx, ret = netfs_begin_read(rreq, true); if (ret < 0) goto error; + netfs_put_request(rreq, false, netfs_rreq_trace_put_return); have_folio: ret = folio_wait_fscache_killable(folio); diff --git a/fs/netfs/io.c b/fs/netfs/io.c index c80b8eed1209..1795f8679be9 100644 --- a/fs/netfs/io.c +++ b/fs/netfs/io.c @@ -362,6 +362,7 @@ static void netfs_rreq_assess(struct netfs_io_request *rreq, bool was_async) netfs_rreq_unlock_folios(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); @@ -657,7 +658,6 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync) 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; } @@ -669,12 +669,10 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync) 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. */ + netfs_get_request(rreq, netfs_rreq_trace_get_for_outstanding); atomic_set(&rreq->nr_outstanding, 1); io_iter = rreq->io_iter; do { @@ -684,25 +682,25 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync) } 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. + /* 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. */ - for (;;) { - wait_var_event(&rreq->nr_outstanding, - atomic_read(&rreq->nr_outstanding) == 1); + 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); - if (!test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags)) - break; - cond_resched(); - } + + 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) { 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)) diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h index 4ea4e34d279f..6daadf2aac8a 100644 --- a/include/trace/events/netfs.h +++ b/include/trace/events/netfs.h @@ -34,7 +34,9 @@ EM(netfs_rreq_trace_free, "FREE ") \ EM(netfs_rreq_trace_resubmit, "RESUBMT") \ EM(netfs_rreq_trace_unlock, "UNLOCK ") \ - E_(netfs_rreq_trace_unmark, "UNMARK ") + EM(netfs_rreq_trace_unmark, "UNMARK ") \ + EM(netfs_rreq_trace_wait_ip, "WAIT-IP") \ + E_(netfs_rreq_trace_wake_ip, "WAKE-IP") #define netfs_sreq_sources \ EM(NETFS_FILL_WITH_ZEROES, "ZERO") \ @@ -65,14 +67,13 @@ E_(netfs_fail_prepare_write, "prep-write") #define netfs_rreq_ref_traces \ - EM(netfs_rreq_trace_get_hold, "GET HOLD ") \ + EM(netfs_rreq_trace_get_for_outstanding,"GET OUTSTND") \ EM(netfs_rreq_trace_get_subreq, "GET SUBREQ ") \ EM(netfs_rreq_trace_put_complete, "PUT COMPLT ") \ EM(netfs_rreq_trace_put_discard, "PUT DISCARD") \ EM(netfs_rreq_trace_put_failed, "PUT FAILED ") \ - EM(netfs_rreq_trace_put_hold, "PUT HOLD ") \ + EM(netfs_rreq_trace_put_return, "PUT RETURN ") \ EM(netfs_rreq_trace_put_subreq, "PUT SUBREQ ") \ - EM(netfs_rreq_trace_put_zero_len, "PUT ZEROLEN") \ E_(netfs_rreq_trace_new, "NEW ") #define netfs_sreq_ref_traces \