From mboxrd@z Thu Jan 1 00:00:00 1970 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 60D09C77B7A for ; Fri, 19 May 2023 22:28:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230172AbjESW2l (ORCPT ); Fri, 19 May 2023 18:28:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229533AbjESW2k (ORCPT ); Fri, 19 May 2023 18:28:40 -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 D0EEF1BD for ; Fri, 19 May 2023 15:27:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684535278; 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=N8SCLY3o4J6b9Y2pJlg3hyrvURsXqrxf9JlUVv4zhn4=; b=eSyPXosWjeUmdw8dXNjSQdSQ/wQ+jhVfPca2v+6G8znUAuXMWsWLEJ5d4AAsEHSTMuDPYM PIhFRE0nNzV+FWc42PTV2K2JNKYQSWCX+HH35OcNqIqSfz58sr/9PMr3PJVPxePA3q66k9 gG6CzPGLYGB95xRowNwaf+lveLVcyrI= Received: from mimecast-mx02.redhat.com (mx3-rdu2.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-626-CHpRL3_TMzyLAsNxrRHseg-1; Fri, 19 May 2023 18:27:54 -0400 X-MC-Unique: CHpRL3_TMzyLAsNxrRHseg-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 124DF2A59551; Fri, 19 May 2023 22:27:54 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.221]) by smtp.corp.redhat.com (Postfix) with ESMTP id C7BB5492B0A; Fri, 19 May 2023 22:27:51 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20230519074047.1739879-1-dhowells@redhat.com> <20230519074047.1739879-4-dhowells@redhat.com> <1742093.1684485814@warthog.procyon.org.uk> To: Christoph Hellwig Cc: dhowells@redhat.com, Jens Axboe , Al Viro , Matthew Wilcox , Jan Kara , Jeff Layton , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , Hillf Danton , Christian Brauner , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig Subject: Re: [PATCH v20 03/32] splice: Make direct_read_splice() limit to eof where appropriate MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2154517.1684535271.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Fri, 19 May 2023 23:27:51 +0100 Message-ID: <2154518.1684535271@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Okay. Let's go with that. So I have to put the handling in vfs_splice_re= ad(): long vfs_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags) { ... if (unlikely(!in->f_op->splice_read)) return warn_unsupported(in, "read"); /* * O_DIRECT and DAX don't deal with the pagecache, so we * allocate a buffer, copy into it and splice that into the pipe. */ if ((in->f_flags & O_DIRECT) || IS_DAX(in->f_mapping->host)) return copy_splice_read(in, ppos, pipe, len, flags); return in->f_op->splice_read(in, ppos, pipe, len, flags); } which leaves very little in generic_file_splice_read: ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags) { if (unlikely(*ppos >=3D in->f_mapping->host->i_sb->s_maxbytes)) return 0; if (unlikely(!len)) return 0; return filemap_splice_read(in, ppos, pipe, len, flags); } so I wonder if the tests in generic_file_splice_read() can be folded into vfs_splice_read(), pointers to generic_file_splice_read() be replaced with pointers to filemap_splice_read() and generic_file_splice_read() just be removed. I suspect we can't quite do this because of the *ppos check - but I wonder= if that's actually necessary since filemap_splice_read() checks against i_size... or if the check can be moved there if we definitely want to do i= t. Certainly, the zero-length check can be done in vfs_splice_read(). David