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Thu, 23 Jan 2020 16:48:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579798124; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IY/4VhvWhbyo1+yBwmrgTORFYZ6C1n23UZLt2zXvGZI=; b=O2lR6yTkc447IFjgQrxD/DpS0oM1YQ7OFxQow/gpAp+x7W1JK4OM32zI+S2DNy/cQMK1P3 iVb1ZRcd6QOMHB1cCOMWZNVlL+nSjWYnIJ5ZxiiVL4vS7rWAlnXFI46MKZQv6oHc/wK7Xt 4Zld7jaufRPLGYjl7vtW1FrnpNM9tis= From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com Subject: [PULL 096/108] virtiofsd: Reset O_DIRECT flag during file open Date: Thu, 23 Jan 2020 16:46:18 +0000 Message-Id: <20200123164630.91498-97-dgilbert@redhat.com> In-Reply-To: <20200123164630.91498-1-dgilbert@redhat.com> References: <20200123164630.91498-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: WoVM-XwMNhWcLHSW55m0-A-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] 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: , 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 Signed-off-by: Dr. David Alan Gilbert --- 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 ccbbec18b0..948cb19c77 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