From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51062) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VtwgK-0005EQ-PO for qemu-devel@nongnu.org; Fri, 20 Dec 2013 04:47:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VtwgF-0000M8-5j for qemu-devel@nongnu.org; Fri, 20 Dec 2013 04:47:44 -0500 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:34421 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VtwgE-0000Lg-RI for qemu-devel@nongnu.org; Fri, 20 Dec 2013 04:47:39 -0500 Message-ID: <52B41279.8060304@kamp.de> Date: Fri, 20 Dec 2013 10:48:41 +0100 From: Peter Lieven MIME-Version: 1.0 References: <1387271725-17060-1-git-send-email-pl@kamp.de> <20131217164730.GD2708@stefanha-thinkpad.redhat.com> In-Reply-To: <20131217164730.GD2708@stefanha-thinkpad.redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCHv2] block: add native support for NFS List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: kwolf@redhat.com, pbonzini@redhat.com, famz@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com On 17.12.2013 17:47, Stefan Hajnoczi wrote: > On Tue, Dec 17, 2013 at 10:15:25AM +0100, Peter Lieven wrote: >> This patch adds native support for accessing images on NFS shares without >> the requirement to actually mount the entire NFS share on the host. >> >> NFS Images can simply be specified by an url of the form: >> nfs://// >> >> For example: >> qemu-img create -f qcow2 nfs://10.0.0.1/qemu-images/test.qcow2 >> >> You need libnfs from Ronnie Sahlberg available at: >> git://github.com/sahlberg/libnfs.git >> for this to work. >> >> During configure it is automatically probed for libnfs and support >> is enabled on-the-fly. You can forbid or enforce libnfs support >> with --disable-libnfs or --enable-libnfs respectively. >> >> Due to NFS restrictions you might need to execute your binaries >> as root, allow them to open priviledged ports (<1024) or specify >> insecure option on the NFS server. >> >> Signed-off-by: Peter Lieven >> --- >> v1->v2: >> - fixed block/Makefile.objs [Ronnie] >> - do not always register a read handler [Ronnie] >> - add support for reading beyond EOF [Fam] >> - fixed struct and paramter naming [Fam] >> - fixed overlong lines and whitespace errors [Fam] >> - return return status from libnfs whereever possible [Fam] >> - added comment why we set allocated_file_size to -ENOTSUP after write [Fam] >> - avoid segfault when parsing filname [Fam] >> - remove unused close_bh from NFSClient [Fam] >> - avoid dividing and mutliplying total_size by BDRV_SECTOR_SIZE in nfs_file_create [Fam] >> >> MAINTAINERS | 5 + >> block/Makefile.objs | 1 + >> block/nfs.c | 419 +++++++++++++++++++++++++++++++++++++++++++++++++++ >> configure | 38 +++++ >> 4 files changed, 463 insertions(+) >> create mode 100644 block/nfs.c > Which NFS protocol versions are supported by current libnfs? > >> +#include > Why is this header included? > >> +typedef struct nfsclient { > Please either drop the struct tag or use "NFSClient". > >> +static void >> +nfs_co_generic_cb(int status, struct nfs_context *nfs, void *data, >> + void *private_data) >> +{ >> + NFSTask *Task = private_data; > lowercase "task" local variable name please. > >> +static int coroutine_fn nfs_co_writev(BlockDriverState *bs, >> + int64_t sector_num, int nb_sectors, >> + QEMUIOVector *iov) >> +{ >> + NFSClient *client = bs->opaque; >> + NFSTask task; >> + char *buf = NULL; >> + >> + nfs_co_init_task(client, &task); >> + >> + buf = g_malloc(nb_sectors * BDRV_SECTOR_SIZE); >> + qemu_iovec_to_buf(iov, 0, buf, nb_sectors * BDRV_SECTOR_SIZE); >> + >> + if (nfs_pwrite_async(client->context, client->fh, >> + sector_num * BDRV_SECTOR_SIZE, >> + nb_sectors * BDRV_SECTOR_SIZE, >> + buf, nfs_co_generic_cb, &task) != 0) { >> + g_free(buf); >> + return -EIO; > Can we get a more detailed errno here? (e.g. ENOSPC) > >> + } >> + >> + while (!task.complete) { >> + nfs_set_events(client); >> + qemu_coroutine_yield(); >> + } >> + >> + g_free(buf); >> + >> + if (task.status != nb_sectors * BDRV_SECTOR_SIZE) { >> + return task.status < 0 ? task.status : -EIO; >> + } >> + >> + bs->total_sectors = MAX(bs->total_sectors, sector_num + nb_sectors); > Why is this necessary? block.c will update bs->total_sectors if the > file is growable. > >> + /* set to -ENOTSUP since bdrv_allocated_file_size is only used >> + * in qemu-img open. So we can use the cached value for allocate >> + * filesize obtained from fstat at open time */ >> + client->allocated_file_size = -ENOTSUP; > Can you implement this fully? By stubbing it out like this we won't be > able to call get_allocated_file_size() at runtime in the future without > updating the nfs block driver code. It's just an fstat call, shouldn't > be too hard to implement properly :). It seems I have to leave it as is currently. bdrv_get_allocated_file_size is not in a coroutine context. I get coroutine yields to no one. Peter