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spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42794 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1legY6-0006Qf-85 for qemu-devel@archiver.kernel.org; Thu, 06 May 2021 12:08:26 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56838) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1legNE-0007J6-OR for qemu-devel@nongnu.org; Thu, 06 May 2021 11:57:12 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:40856) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1legNC-0000JL-AJ for qemu-devel@nongnu.org; Thu, 06 May 2021 11:57:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620316629; 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=DRlkmhP5zjoJNIqhidtdN3boKr7mUM9O3cGKDv2r7Ko=; b=Vf/Rq35EnPnWFimAAzibr+lzkgyIxq7QJPFsHs5qoO7OjI7T0WCQx54jh/o9EP8IRyrBaE n6z4oY7BL6eLKelIFdbkOq7x/8Xr2VJ3k3EHjwTMXL2Ll1Q0XZuqIdfDzLS3SMKiuM0n68 zE/lRUOnZXnmI8QFkGb0uu2LE+6HeZI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-238-apm16VI-OX-5Z0-P-Rqt-Q-1; Thu, 06 May 2021 11:57:05 -0400 X-MC-Unique: apm16VI-OX-5Z0-P-Rqt-Q-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 43241801107; Thu, 6 May 2021 15:57:03 +0000 (UTC) Received: from work-vm (ovpn-115-37.ams2.redhat.com [10.36.115.37]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CF46760C25; Thu, 6 May 2021 15:56:52 +0000 (UTC) Date: Thu, 6 May 2021 16:56:50 +0100 From: "Dr. David Alan Gilbert" To: qemu-devel@nongnu.org, vgoyal@redhat.com, stefanha@redhat.com, groug@kaod.org Subject: Re: [PATCH v3 02/26] virtiofsd: Don't assume header layout Message-ID: References: <20210428110100.27757-1-dgilbert@redhat.com> <20210428110100.27757-3-dgilbert@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210428110100.27757-3-dgilbert@redhat.com> User-Agent: Mutt/2.0.6 (2021-03-06) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.69, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: virtio-fs@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Dr. David Alan Gilbert (git) (dgilbert@redhat.com) wrote: > From: "Dr. David Alan Gilbert" > > virtiofsd incorrectly assumed a fixed set of header layout in the virt > queue; assuming that the fuse and write headers were conveniently > separated from the data; the spec doesn't allow us to take that > convenience, so fix it up to deal with it the hard way. > > Signed-off-by: Dr. David Alan Gilbert Queued this 2/26 only > --- > tools/virtiofsd/fuse_virtio.c | 94 +++++++++++++++++++++++++++-------- > 1 file changed, 73 insertions(+), 21 deletions(-) > > diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c > index 3e13997406..6dd73c9b72 100644 > --- a/tools/virtiofsd/fuse_virtio.c > +++ b/tools/virtiofsd/fuse_virtio.c > @@ -129,18 +129,55 @@ static void fv_panic(VuDev *dev, const char *err) > * Copy from an iovec into a fuse_buf (memory only) > * Caller must ensure there is space > */ > -static void copy_from_iov(struct fuse_buf *buf, size_t out_num, > - const struct iovec *out_sg) > +static size_t copy_from_iov(struct fuse_buf *buf, size_t out_num, > + const struct iovec *out_sg, > + size_t max) > { > void *dest = buf->mem; > + size_t copied = 0; > > - while (out_num) { > + while (out_num && max) { > size_t onelen = out_sg->iov_len; > + onelen = MIN(onelen, max); > memcpy(dest, out_sg->iov_base, onelen); > dest += onelen; > + copied += onelen; > out_sg++; > out_num--; > + max -= onelen; > } > + > + return copied; > +} > + > +/* > + * Skip 'skip' bytes in the iov; 'sg_1stindex' is set as > + * the index for the 1st iovec to read data from, and > + * 'sg_1stskip' is the number of bytes to skip in that entry. > + * > + * Returns True if there are at least 'skip' bytes in the iovec > + * > + */ > +static bool skip_iov(const struct iovec *sg, size_t sg_size, > + size_t skip, > + size_t *sg_1stindex, size_t *sg_1stskip) > +{ > + size_t vec; > + > + for (vec = 0; vec < sg_size; vec++) { > + if (sg[vec].iov_len > skip) { > + *sg_1stskip = skip; > + *sg_1stindex = vec; > + > + return true; > + } > + > + skip -= sg[vec].iov_len; > + } > + > + *sg_1stindex = vec; > + *sg_1stskip = 0; > + return skip == 0; > } > > /* > @@ -457,6 +494,7 @@ static void fv_queue_worker(gpointer data, gpointer user_data) > bool allocated_bufv = false; > struct fuse_bufvec bufv; > struct fuse_bufvec *pbufv; > + struct fuse_in_header inh; > > assert(se->bufsize > sizeof(struct fuse_in_header)); > > @@ -505,14 +543,15 @@ static void fv_queue_worker(gpointer data, gpointer user_data) > elem->index); > assert(0); /* TODO */ > } > - /* Copy just the first element and look at it */ > - copy_from_iov(&fbuf, 1, out_sg); > + /* Copy just the fuse_in_header and look at it */ > + copy_from_iov(&fbuf, out_num, out_sg, > + sizeof(struct fuse_in_header)); > + memcpy(&inh, fbuf.mem, sizeof(struct fuse_in_header)); > > pbufv = NULL; /* Compiler thinks an unitialised path */ > - if (out_num > 2 && > - out_sg[0].iov_len == sizeof(struct fuse_in_header) && > - ((struct fuse_in_header *)fbuf.mem)->opcode == FUSE_WRITE && > - out_sg[1].iov_len == sizeof(struct fuse_write_in)) { > + if (inh.opcode == FUSE_WRITE && > + out_len >= (sizeof(struct fuse_in_header) + > + sizeof(struct fuse_write_in))) { > /* > * For a write we don't actually need to copy the > * data, we can just do it straight out of guest memory > @@ -521,15 +560,15 @@ static void fv_queue_worker(gpointer data, gpointer user_data) > */ > fuse_log(FUSE_LOG_DEBUG, "%s: Write special case\n", __func__); > > - /* copy the fuse_write_in header afte rthe fuse_in_header */ > - fbuf.mem += out_sg->iov_len; > - copy_from_iov(&fbuf, 1, out_sg + 1); > - fbuf.mem -= out_sg->iov_len; > - fbuf.size = out_sg[0].iov_len + out_sg[1].iov_len; > + fbuf.size = copy_from_iov(&fbuf, out_num, out_sg, > + sizeof(struct fuse_in_header) + > + sizeof(struct fuse_write_in)); > + /* That copy reread the in_header, make sure we use the original */ > + memcpy(fbuf.mem, &inh, sizeof(struct fuse_in_header)); > > /* Allocate the bufv, with space for the rest of the iov */ > pbufv = malloc(sizeof(struct fuse_bufvec) + > - sizeof(struct fuse_buf) * (out_num - 2)); > + sizeof(struct fuse_buf) * out_num); > if (!pbufv) { > fuse_log(FUSE_LOG_ERR, "%s: pbufv malloc failed\n", > __func__); > @@ -540,24 +579,37 @@ static void fv_queue_worker(gpointer data, gpointer user_data) > pbufv->count = 1; > pbufv->buf[0] = fbuf; > > - size_t iovindex, pbufvindex; > - iovindex = 2; /* 2 headers, separate iovs */ > + size_t iovindex, pbufvindex, iov_bytes_skip; > pbufvindex = 1; /* 2 headers, 1 fusebuf */ > > + if (!skip_iov(out_sg, out_num, > + sizeof(struct fuse_in_header) + > + sizeof(struct fuse_write_in), > + &iovindex, &iov_bytes_skip)) { > + fuse_log(FUSE_LOG_ERR, "%s: skip failed\n", > + __func__); > + goto out; > + } > + > for (; iovindex < out_num; iovindex++, pbufvindex++) { > pbufv->count++; > pbufv->buf[pbufvindex].pos = ~0; /* Dummy */ > pbufv->buf[pbufvindex].flags = 0; > pbufv->buf[pbufvindex].mem = out_sg[iovindex].iov_base; > pbufv->buf[pbufvindex].size = out_sg[iovindex].iov_len; > + > + if (iov_bytes_skip) { > + pbufv->buf[pbufvindex].mem += iov_bytes_skip; > + pbufv->buf[pbufvindex].size -= iov_bytes_skip; > + iov_bytes_skip = 0; > + } > } > } else { > /* Normal (non fast write) path */ > > - /* Copy the rest of the buffer */ > - fbuf.mem += out_sg->iov_len; > - copy_from_iov(&fbuf, out_num - 1, out_sg + 1); > - fbuf.mem -= out_sg->iov_len; > + copy_from_iov(&fbuf, out_num, out_sg, se->bufsize); > + /* That copy reread the in_header, make sure we use the original */ > + memcpy(fbuf.mem, &inh, sizeof(struct fuse_in_header)); > fbuf.size = out_len; > > /* TODO! Endianness of header */ > -- > 2.31.1 > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK