From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 01D6B30FF20; Tue, 31 Mar 2026 17:10:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774977020; cv=none; b=Jv2+mn9PfLBgEsgQPAeTfUnbG4mGaXAEyCb7YgepomkPgL8mg5Ji8Zbg03GIe2RnF9JuaTscb2hPnaeZP2GT6jrfJ/QcYEtjAeBG0G9IjnYLMxQiPw3UjlkNeliz593tCKO3P0C8k9Rq1L3E19S/IxZgEdo+2ISzeA+MeJ0e+1A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774977020; c=relaxed/simple; bh=0O7pbVwcKP6zzxAn3nAxvdvlnhR1hbnc9pRjVpoFrKg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=M59HuFkL8JJ53NcNKfq5Ato4ktXC5bBU7skdPdgHmr4RYglqppB7yttIBqgjZ4BmzJABxZEde5OKesRSW8mtrPKrxyh39WRKHcUyj8B1QnV4afqsdFhaP6MA5vEgtjBBSTAEm8PgpIHq360a7WaivkiJam+U5KNJ06Q/6dRTFiQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OJkkXCGu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="OJkkXCGu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87B27C2BCB1; Tue, 31 Mar 2026 17:10:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774977019; bh=0O7pbVwcKP6zzxAn3nAxvdvlnhR1hbnc9pRjVpoFrKg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OJkkXCGuYXwWU9+ews6h1BF7pgGCBCu9dNBTOf1W/MSjlzUbaAbJEHjBtLjQtTyap bh3AIqgx3x454fjP82U3ysLDaHEc9aBic3DG3xSF3JuK9mxbaZda22GA9il09op9Ql mGrQXAkR13w+gte4DIR2H8NF9ygobcQqfqojj2lU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Paulo Alcantara , David Howells , netfs@lists.linux.dev, linux-fsdevel@vger.kernel.org, Christian Brauner , Sasha Levin Subject: [PATCH 6.18 305/309] netfs: Fix the handling of stream->front by removing it Date: Tue, 31 Mar 2026 18:23:28 +0200 Message-ID: <20260331161804.790300354@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260331161753.468533260@linuxfoundation.org> References: <20260331161753.468533260@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Howells [ Upstream commit 0e764b9d46071668969410ec5429be0e2f38c6d3 ] The netfs_io_stream::front member is meant to point to the subrequest currently being collected on a stream, but it isn't actually used this way by direct write (which mostly ignores it). However, there's a tracepoint which looks at it. Further, stream->front is actually redundant with stream->subrequests.next. Fix the potential problem in the direct code by just removing the member and using stream->subrequests.next instead, thereby also simplifying the code. Fixes: a0b4c7a49137 ("netfs: Fix unbuffered/DIO writes to dispatch subrequests in strict sequence") Reported-by: Paulo Alcantara Signed-off-by: David Howells Link: https://patch.msgid.link/4158599.1774426817@warthog.procyon.org.uk Reviewed-by: Paulo Alcantara (Red Hat) cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/netfs/buffered_read.c | 3 +-- fs/netfs/direct_read.c | 3 +-- fs/netfs/direct_write.c | 1 - fs/netfs/read_collect.c | 4 ++-- fs/netfs/read_single.c | 1 - fs/netfs/write_collect.c | 4 ++-- fs/netfs/write_issue.c | 3 +-- include/linux/netfs.h | 1 - include/trace/events/netfs.h | 8 ++++---- 9 files changed, 11 insertions(+), 17 deletions(-) diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index 37ab6f28b5ad0..88361e8c70961 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -171,9 +171,8 @@ static void netfs_queue_read(struct netfs_io_request *rreq, spin_lock(&rreq->lock); list_add_tail(&subreq->rreq_link, &stream->subrequests); if (list_is_first(&subreq->rreq_link, &stream->subrequests)) { - stream->front = subreq; if (!stream->active) { - stream->collected_to = stream->front->start; + stream->collected_to = subreq->start; /* Store list pointers before active flag */ smp_store_release(&stream->active, true); } diff --git a/fs/netfs/direct_read.c b/fs/netfs/direct_read.c index a498ee8d66745..f72e6da88cca7 100644 --- a/fs/netfs/direct_read.c +++ b/fs/netfs/direct_read.c @@ -71,9 +71,8 @@ static int netfs_dispatch_unbuffered_reads(struct netfs_io_request *rreq) spin_lock(&rreq->lock); list_add_tail(&subreq->rreq_link, &stream->subrequests); if (list_is_first(&subreq->rreq_link, &stream->subrequests)) { - stream->front = subreq; if (!stream->active) { - stream->collected_to = stream->front->start; + stream->collected_to = subreq->start; /* Store list pointers before active flag */ smp_store_release(&stream->active, true); } diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c index 4d9760e36c119..f9ab69de3e298 100644 --- a/fs/netfs/direct_write.c +++ b/fs/netfs/direct_write.c @@ -111,7 +111,6 @@ static int netfs_unbuffered_write(struct netfs_io_request *wreq) netfs_prepare_write(wreq, stream, wreq->start + wreq->transferred); subreq = stream->construct; stream->construct = NULL; - stream->front = NULL; } /* Check if (re-)preparation failed. */ diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c index 137f0e28a44c5..e5f6665b3341e 100644 --- a/fs/netfs/read_collect.c +++ b/fs/netfs/read_collect.c @@ -205,7 +205,8 @@ static void netfs_collect_read_results(struct netfs_io_request *rreq) * in progress. The issuer thread may be adding stuff to the tail * whilst we're doing this. */ - front = READ_ONCE(stream->front); + front = list_first_entry_or_null(&stream->subrequests, + struct netfs_io_subrequest, rreq_link); while (front) { size_t transferred; @@ -301,7 +302,6 @@ static void netfs_collect_read_results(struct netfs_io_request *rreq) list_del_init(&front->rreq_link); front = list_first_entry_or_null(&stream->subrequests, struct netfs_io_subrequest, rreq_link); - stream->front = front; spin_unlock(&rreq->lock); netfs_put_subrequest(remove, notes & ABANDON_SREQ ? diff --git a/fs/netfs/read_single.c b/fs/netfs/read_single.c index 5c0dc4efc7922..9d48ced80d1fa 100644 --- a/fs/netfs/read_single.c +++ b/fs/netfs/read_single.c @@ -107,7 +107,6 @@ static int netfs_single_dispatch_read(struct netfs_io_request *rreq) spin_lock(&rreq->lock); list_add_tail(&subreq->rreq_link, &stream->subrequests); trace_netfs_sreq(subreq, netfs_sreq_trace_added); - stream->front = subreq; /* Store list pointers before active flag */ smp_store_release(&stream->active, true); spin_unlock(&rreq->lock); diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c index 83eb3dc1adf8a..b194447f4b111 100644 --- a/fs/netfs/write_collect.c +++ b/fs/netfs/write_collect.c @@ -228,7 +228,8 @@ static void netfs_collect_write_results(struct netfs_io_request *wreq) if (!smp_load_acquire(&stream->active)) continue; - front = stream->front; + front = list_first_entry_or_null(&stream->subrequests, + struct netfs_io_subrequest, rreq_link); while (front) { trace_netfs_collect_sreq(wreq, front); //_debug("sreq [%x] %llx %zx/%zx", @@ -279,7 +280,6 @@ static void netfs_collect_write_results(struct netfs_io_request *wreq) list_del_init(&front->rreq_link); front = list_first_entry_or_null(&stream->subrequests, struct netfs_io_subrequest, rreq_link); - stream->front = front; spin_unlock(&wreq->lock); netfs_put_subrequest(remove, notes & SAW_FAILURE ? diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c index 437268f656409..2db688f941251 100644 --- a/fs/netfs/write_issue.c +++ b/fs/netfs/write_issue.c @@ -206,9 +206,8 @@ void netfs_prepare_write(struct netfs_io_request *wreq, spin_lock(&wreq->lock); list_add_tail(&subreq->rreq_link, &stream->subrequests); if (list_is_first(&subreq->rreq_link, &stream->subrequests)) { - stream->front = subreq; if (!stream->active) { - stream->collected_to = stream->front->start; + stream->collected_to = subreq->start; /* Write list pointers before active flag */ smp_store_release(&stream->active, true); } diff --git a/include/linux/netfs.h b/include/linux/netfs.h index 72ee7d210a744..ba17ac5bf356a 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -140,7 +140,6 @@ struct netfs_io_stream { void (*issue_write)(struct netfs_io_subrequest *subreq); /* Collection tracking */ struct list_head subrequests; /* Contributory I/O operations */ - struct netfs_io_subrequest *front; /* Op being collected */ unsigned long long collected_to; /* Position we've collected results to */ size_t transferred; /* The amount transferred from this stream */ unsigned short error; /* Aggregate error for the stream */ diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h index 2d366be46a1c3..cbe28211106c5 100644 --- a/include/trace/events/netfs.h +++ b/include/trace/events/netfs.h @@ -740,19 +740,19 @@ TRACE_EVENT(netfs_collect_stream, __field(unsigned int, wreq) __field(unsigned char, stream) __field(unsigned long long, collected_to) - __field(unsigned long long, front) + __field(unsigned long long, issued_to) ), TP_fast_assign( __entry->wreq = wreq->debug_id; __entry->stream = stream->stream_nr; __entry->collected_to = stream->collected_to; - __entry->front = stream->front ? stream->front->start : UINT_MAX; + __entry->issued_to = atomic64_read(&wreq->issued_to); ), - TP_printk("R=%08x[%x:] cto=%llx frn=%llx", + TP_printk("R=%08x[%x:] cto=%llx ito=%llx", __entry->wreq, __entry->stream, - __entry->collected_to, __entry->front) + __entry->collected_to, __entry->issued_to) ); TRACE_EVENT(netfs_folioq, -- 2.53.0