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Tue, 21 Jan 2020 12:32:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579609952; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JTpjZPadHNrcDZKv51V6CLKGvZ7oo/FweuUesYbxnBo=; b=GEhcFCQqJImsnsNcK4QDopz4MtGHF1TZwN27/vCFETzld0RR40uHb7z0pHlHrughRYKIE6 SqJyYfABqrEk8NhdZTkdmKHgAIEBDD/P78rqsT19g6E95ULBcZ3nbrp/vx2jlT+qdauc4g PYvRuPeqQCZVCRAp36LsVQHtMKPHT7k= From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com, vgoyal@redhat.com, berrange@redhat.com, slp@redhat.com, philmd@redhat.com Subject: [PATCH v2 098/109] virtiofsd: Reset O_DIRECT flag during file open Date: Tue, 21 Jan 2020 12:24:22 +0000 Message-Id: <20200121122433.50803-99-dgilbert@redhat.com> In-Reply-To: <20200121122433.50803-1-dgilbert@redhat.com> References: <20200121122433.50803-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: rMHCKgNHNhS0wpgAnik7nA-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: m.mizuma@jp.fujitsu.com, misono.tomohiro@jp.fujitsu.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) Content-Type: text/plain; charset="utf-8" From: Vivek Goyal If an application wants to do direct IO and opens a file with O_DIRECT in guest, that does not necessarily mean that we need to bypass page cache on host as well. So reset this flag on host. If somebody needs to bypass page cache on host as well (and it is safe to do so), we can add a knob in daemon later to control this behavior. I check virtio-9p and they do reset O_DIRECT flag. Signed-off-by: Vivek Goyal Reviewed-by: Daniel P. Berrang=C3=A9 --- tools/virtiofsd/passthrough_ll.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough= _ll.c index 4c3a48325f..cadfa676ca 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -1721,6 +1721,13 @@ static void lo_create(fuse_req_t req, fuse_ino_t par= ent, const char *name, goto out; } =20 + /* + * O_DIRECT in guest should not necessarily mean bypassing page + * cache on host as well. If somebody needs that behavior, it + * probably should be a configuration knob in daemon. + */ + fi->flags &=3D ~O_DIRECT; + fd =3D openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOL= LOW, mode); err =3D fd =3D=3D -1 ? errno : 0; @@ -1950,6 +1957,13 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, = struct fuse_file_info *fi) fi->flags &=3D ~O_APPEND; } =20 + /* + * O_DIRECT in guest should not necessarily mean bypassing page + * cache on host as well. If somebody needs that behavior, it + * probably should be a configuration knob in daemon. + */ + fi->flags &=3D ~O_DIRECT; + sprintf(buf, "%i", lo_fd(req, ino)); fd =3D openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW); if (fd =3D=3D -1) { --=20 2.24.1