From patchwork Tue Jan 18 13:54:16 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12716422 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 3435EC433F5 for ; Tue, 18 Jan 2022 13:54:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244275AbiARNyk (ORCPT ); Tue, 18 Jan 2022 08:54:40 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:60028 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244414AbiARNy3 (ORCPT ); Tue, 18 Jan 2022 08:54:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642514069; 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=GZzU3Qzlz4du0HJk3pIy88pOD0oFL5+7cfgc4MIvSjc=; b=FUz9kKzf3K2GeERiUUxyKjTkfE+nRlRJn0VC7LcluIESDZc8cxZb1Vfeo+d2EVOT4Voq2r h3WraYqIyJPs74i1BQ+ZdR15zujBQhYnZudyJpN1xApFLf1bD6l+ibga+hP+d+Rn6vNo58 as6Hnu6ZzxhWYW3YmlJrgYVKCxxlrZk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-562-iXKYrVelNbCgNPklJReXeg-1; Tue, 18 Jan 2022 08:54:26 -0500 X-MC-Unique: iXKYrVelNbCgNPklJReXeg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 56DF0100C625; Tue, 18 Jan 2022 13:54:20 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.165]) by smtp.corp.redhat.com (Postfix) with ESMTP id 12AF77A3F9; Tue, 18 Jan 2022 13:54:16 +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 Subject: [PATCH 06/11] cachefiles: Explain checks in a comment From: David Howells To: linux-cachefs@redhat.com Cc: Jeff Layton , Jeff Layton , dhowells@redhat.com, Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Jeff Layton , Matthew Wilcox , Alexander Viro , Omar Sandoval , JeffleXu , Linus Torvalds , linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 18 Jan 2022 13:54:16 +0000 Message-ID: <164251405621.3435901.771439791811515914.stgit@warthog.procyon.org.uk> In-Reply-To: <164251396932.3435901.344517748027321142.stgit@warthog.procyon.org.uk> References: <164251396932.3435901.344517748027321142.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Add a comment to explain the checks that cachefiles is making of the backing filesystem[1]. Suggested-by: Jeff Layton Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/568749bd7cc02908ecf6f3d6a611b6f9cf5c4afd.camel@kernel.org/ [1] --- fs/cachefiles/cache.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/cachefiles/cache.c b/fs/cachefiles/cache.c index 1e9c71666c6a..2b2879c5d1d2 100644 --- a/fs/cachefiles/cache.c +++ b/fs/cachefiles/cache.c @@ -49,7 +49,13 @@ int cachefiles_add_cache(struct cachefiles_cache *cache) goto error_unsupported; } - /* check parameters */ + /* Check features of the backing filesystem: + * - Directories must support looking up and directory creation + * - We use xattrs to store metadata + * - We need to be able to query the amount of space available + * - We want to be able to sync the filesystem when stopping the cache + * - We use DIO to/from pages, so the blocksize mustn't be too big. + */ ret = -EOPNOTSUPP; if (d_is_negative(root) || !d_backing_inode(root)->i_op->lookup ||