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 BE1D9C4321E for ; Mon, 28 Nov 2022 20:10:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233293AbiK1UKz (ORCPT ); Mon, 28 Nov 2022 15:10:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232238AbiK1UKy (ORCPT ); Mon, 28 Nov 2022 15:10:54 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13824FAD5 for ; Mon, 28 Nov 2022 12:09:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669666193; 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: in-reply-to:in-reply-to:references:references; bh=WD+oeQLh4B1x5wzvULEGlFAwsWW0xKv+aoBTkSWPAzU=; b=YGlOqLH/QtaT9/geu2IMxOkFsl0uDrTWLEUq9BHucwsc3WcNjyfxhVo3g1bwqmPpY013rf H1wqY/gMS7jUwNNaEPrhB+IcK8wzsEbgCBjVkMLqtIit+h+iyVU/2UPDQzbTv/pWrXL6Ek yo3/JV50sE54pCN3se2KAmZ38cnD9wE= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-327-IBnM0iesPDqHdYebJJ80Vg-1; Mon, 28 Nov 2022 15:09:47 -0500 X-MC-Unique: IBnM0iesPDqHdYebJJ80Vg-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C680C811E81; Mon, 28 Nov 2022 20:09:46 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.9.12]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AFF0A4A9254; Mon, 28 Nov 2022 20:09:46 +0000 (UTC) Received: by fedora.redhat.com (Postfix, from userid 1000) id DB53CB680E; Mon, 28 Nov 2022 15:09:43 -0500 (EST) Date: Mon, 28 Nov 2022 15:09:43 -0500 From: Vivek Goyal To: Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org, Pengfei Xu , syzbot+462da39f0667b357c4b6@syzkaller.appspotmail.com Subject: Re: [PATCH] fuse: lock inode unconditionally in fuse_fallocate() Message-ID: References: <20221123104336.1030702-1-mszeredi@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221123104336.1030702-1-mszeredi@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Nov 23, 2022 at 11:43:36AM +0100, Miklos Szeredi wrote: > file_modified() must be called with inode lock held. fuse_fallocate() > didn't lock the inode in case of just FALLOC_KEEP_SIZE flags value, which > resulted in a kernel Warning in notify_change(). > > Lock the inode unconditionally, like all other fallocate implementations > do. > > Reported-by: Pengfei Xu > Reported-and-tested-by: syzbot+462da39f0667b357c4b6@syzkaller.appspotmail.com > Fixes: 4a6f278d4827 ("fuse: add file_modified() to fallocate") > Signed-off-by: Miklos Szeredi > --- > fs/fuse/file.c | 37 ++++++++++++++++--------------------- > 1 file changed, 16 insertions(+), 21 deletions(-) > > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index 71bfb663aac5..89f4741728ba 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -2963,11 +2963,9 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, > .mode = mode > }; > int err; > - bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) || > - (mode & (FALLOC_FL_PUNCH_HOLE | > - FALLOC_FL_ZERO_RANGE)); > - > - bool block_faults = FUSE_IS_DAX(inode) && lock_inode; > + bool block_faults = FUSE_IS_DAX(inode) && > + (!(mode & FALLOC_FL_KEEP_SIZE) || > + (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))); Hi Miklos, I think that we probably don't need above tests for "block_faults". Initially, ideas was that I wanted to synchronize truncate/punch_hole with fault handler path. Fuse did not seem to do it, so I decided to add it only for fuse DAX code to begin with. Details are in following commit. commit 6ae330cad6ef22ab8347ea9e0707dc56a7c7363f Author: Vivek Goyal Date: Wed Aug 19 18:19:54 2020 -0400 virtiofs: serialize truncate/punch_hole and dax fault path I wanted to take following two locks for it to work. inode_lock(inode) down_write(&fi->i_mmap_sem); And that's why following condition. bool block_faults = FUSE_IS_DAX(inode) && lock_inode; Given that we will now always take inode lock, we could just do. bool block_faults = FUSE_IS_DAX(inode); instead. Not sure is there really a benefit in going through different "mode" flags and make this condition even narrower. I see that now fi->i_mmap_sem has been replaced by filemap_invalidate_lock(inode->i_mapping). At some point of time we should review fuse fault code and see if that code need to serialize with truncate/punch_hole path as well. If answer is yes, then we could get rid of this "block_faults" altogether and always take inode->i_mapping lock in truncate path. IOW, I think we should be able to simplify above to just for now. bool block_faults = FUSE_IS_DAX(inode); Thanks Vivek > > if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | > FALLOC_FL_ZERO_RANGE)) > @@ -2976,22 +2974,20 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, > if (fm->fc->no_fallocate) > return -EOPNOTSUPP; > > - if (lock_inode) { > - inode_lock(inode); > - if (block_faults) { > - filemap_invalidate_lock(inode->i_mapping); > - err = fuse_dax_break_layouts(inode, 0, 0); > - if (err) > - goto out; > - } > + inode_lock(inode); > + if (block_faults) { > + filemap_invalidate_lock(inode->i_mapping); > + err = fuse_dax_break_layouts(inode, 0, 0); > + if (err) > + goto out; > + } > > - if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) { > - loff_t endbyte = offset + length - 1; > + if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) { > + loff_t endbyte = offset + length - 1; > > - err = fuse_writeback_range(inode, offset, endbyte); > - if (err) > - goto out; > - } > + err = fuse_writeback_range(inode, offset, endbyte); > + if (err) > + goto out; > } > > if (!(mode & FALLOC_FL_KEEP_SIZE) && > @@ -3039,8 +3035,7 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, > if (block_faults) > filemap_invalidate_unlock(inode->i_mapping); > > - if (lock_inode) > - inode_unlock(inode); > + inode_unlock(inode); > > fuse_flush_time_update(inode); > > -- > 2.38.1 >