Re: [Qemu-devel] [PATCHv7 1/5] block: add native support for NFS

[Stefan Hajnoczi]

On Thu, Jan 30, 2014 at 10:12:35AM +0100, Peter Lieven wrote:
> 
> Am 30.01.2014 um 10:05 schrieb Stefan Hajnoczi <address@hidden>:
> 
> > On Wed, Jan 29, 2014 at 05:38:29PM +0100, Peter Lieven wrote:
> >> On 29.01.2014 17:19, Benoît Canet wrote:
> >>> Le Wednesday 29 Jan 2014 à 09:50:21 (+0100), Peter Lieven a écrit :
> >>>> 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://<host>/<export>/<filename>[?param=value[&param2=value2[&...]]]
> >>>> 
> >>>> 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.
> >>>> 
> >>>> For additional information on ROOT vs. non-ROOT operation and URL
> >>>> format + parameters see:
> >>>>   https://raw.github.com/sahlberg/libnfs/master/README
> >>>> 
> >>>> Supported by qemu are the uid, gid and tcp-syncnt URL parameters.
> >>>> 
> >>>> LibNFS currently support NFS version 3 only.
> >>>> 
> >>>> Signed-off-by: Peter Lieven <address@hidden>
> >>>> ---
> >>>> MAINTAINERS         |    5 +
> >>>> block/Makefile.objs |    1 +
> >>>> block/nfs.c         |  440 
> >>>> +++++++++++++++++++++++++++++++++++++++++++++++++++
> >>>> configure           |   26 +++
> >>>> qapi-schema.json    |    1 +
> >>>> 5 files changed, 473 insertions(+)
> >>>> create mode 100644 block/nfs.c
> >>>> 
> >>>> diff --git a/MAINTAINERS b/MAINTAINERS
> >>>> index fb53242..f8411f9 100644
> >>>> --- a/MAINTAINERS
> >>>> +++ b/MAINTAINERS
> >>>> @@ -936,6 +936,11 @@ M: Peter Lieven <address@hidden>
> >>>> S: Supported
> >>>> F: block/iscsi.c
> >>>> +NFS
> >>>> +M: Peter Lieven <address@hidden>
> >>>> +S: Maintained
> >>>> +F: block/nfs.c
> >>>> +
> >>>> SSH
> >>>> M: Richard W.M. Jones <address@hidden>
> >>>> S: Supported
> >>>> diff --git a/block/Makefile.objs b/block/Makefile.objs
> >>>> index 4e8c91e..e254a21 100644
> >>>> --- a/block/Makefile.objs
> >>>> +++ b/block/Makefile.objs
> >>>> @@ -12,6 +12,7 @@ block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o
> >>>> ifeq ($(CONFIG_POSIX),y)
> >>>> block-obj-y += nbd.o nbd-client.o sheepdog.o
> >>>> block-obj-$(CONFIG_LIBISCSI) += iscsi.o
> >>>> +block-obj-$(CONFIG_LIBNFS) += nfs.o
> >>>> block-obj-$(CONFIG_CURL) += curl.o
> >>>> block-obj-$(CONFIG_RBD) += rbd.o
> >>>> block-obj-$(CONFIG_GLUSTERFS) += gluster.o
> >>>> diff --git a/block/nfs.c b/block/nfs.c
> >>>> new file mode 100644
> >>>> index 0000000..2bbf7a2
> >>>> --- /dev/null
> >>>> +++ b/block/nfs.c
> >>>> @@ -0,0 +1,440 @@
> >>>> +/*
> >>>> + * QEMU Block driver for native access to files on NFS shares
> >>>> + *
> >>>> + * Copyright (c) 2014 Peter Lieven <address@hidden>
> >>>> + *
> >>>> + * Permission is hereby granted, free of charge, to any person 
> >>>> obtaining a copy
> >>>> + * of this software and associated documentation files (the 
> >>>> "Software"), to deal
> >>>> + * in the Software without restriction, including without limitation 
> >>>> the rights
> >>>> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or 
> >>>> sell
> >>>> + * copies of the Software, and to permit persons to whom the Software is
> >>>> + * furnished to do so, subject to the following conditions:
> >>>> + *
> >>>> + * The above copyright notice and this permission notice shall be 
> >>>> included in
> >>>> + * all copies or substantial portions of the Software.
> >>>> + *
> >>>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
> >>>> EXPRESS OR
> >>>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
> >>>> MERCHANTABILITY,
> >>>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT 
> >>>> SHALL
> >>>> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 
> >>>> OTHER
> >>>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 
> >>>> ARISING FROM,
> >>>> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
> >>>> DEALINGS IN
> >>>> + * THE SOFTWARE.
> >>>> + */
> >>>> +
> >>>> +#include "config-host.h"
> >>>> +
> >>>> +#include <poll.h>
> >>>> +#include "qemu-common.h"
> >>>> +#include "qemu/config-file.h"
> >>>> +#include "qemu/error-report.h"
> >>>> +#include "block/block_int.h"
> >>>> +#include "trace.h"
> >>>> +#include "qemu/iov.h"
> >>>> +#include "qemu/uri.h"
> >>>> +#include "sysemu/sysemu.h"
> >>>> +#include <nfsc/libnfs.h>
> >>>> +
> >>>> +typedef struct NFSClient {
> >>>> +    struct nfs_context *context;
> >>>> +    struct nfsfh *fh;
> >>>> +    int events;
> >>>> +    bool has_zero_init;
> >>>> +} NFSClient;
> >>>> +
> >>>> +typedef struct NFSRPC {
> >>>> +    int status;
> >>>> +    int complete;
> >>>> +    QEMUIOVector *iov;
> >>>> +    struct stat *st;
> >>>> +    Coroutine *co;
> >>>> +    QEMUBH *bh;
> >>>> +} NFSRPC;
> >>>> +
> >>>> +static void nfs_process_read(void *arg);
> >>>> +static void nfs_process_write(void *arg);
> >>>> +
> >>>> +static void nfs_set_events(NFSClient *client)
> >>>> +{
> >>>> +    int ev = nfs_which_events(client->context);
> >>>> +    if (ev != client->events) {
> >>>> +        qemu_aio_set_fd_handler(nfs_get_fd(client->context),
> >>>> +                      (ev & POLLIN) ? nfs_process_read : NULL,
> >>>> +                      (ev & POLLOUT) ? nfs_process_write : NULL,
> >>>> +                      client);
> >>>> +
> >>>> +    }
> >>>> +    client->events = ev;
> >>>> +}
> >>>> +
> >>>> +static void nfs_process_read(void *arg)
> >>>> +{
> >>>> +    NFSClient *client = arg;
> >>>> +    nfs_service(client->context, POLLIN);
> >>>> +    nfs_set_events(client);
> >>>> +}
> >>>> +
> >>>> +static void nfs_process_write(void *arg)
> >>>> +{
> >>>> +    NFSClient *client = arg;
> >>>> +    nfs_service(client->context, POLLOUT);
> >>>> +    nfs_set_events(client);
> >>>> +}
> >>>> +
> >>>> +static void nfs_co_init_task(NFSClient *client, NFSRPC *task)
> >>>> +{
> >>>> +    *task = (NFSRPC) {
> >>>> +        .co         = qemu_coroutine_self(),
> >>>> +    };
> >>>> +}
> >>>> +
> >>>> +static void nfs_co_generic_bh_cb(void *opaque)
> >>>> +{
> >>>> +    NFSRPC *task = opaque;
> >>>> +    qemu_bh_delete(task->bh);
> >>>> +    qemu_coroutine_enter(task->co, NULL);
> >>>> +}
> >>>> +
> >>>> +static void
> >>>> +nfs_co_generic_cb(int status, struct nfs_context *nfs, void *data,
> >>>> +                  void *private_data)
> >>>> +{
> >>>> +    NFSRPC *task = private_data;
> >>>> +    task->complete = 1;
> >>>> +    task->status = status;
> >>>> +    if (task->status > 0 && task->iov) {
> >>>> +        if (task->status <= task->iov->size) {
> >>> It feel very odd to compare something named status with something named 
> >>> size.
> >>> 
> >>>> +            qemu_iovec_from_buf(task->iov, 0, data, task->status);
> >>>> +        } else {
> >>>> +            task->status = -EIO;
> >>>> +        }
> >>>> +    }
> >>>> +    if (task->status == 0 && task->st) {
> >>>> +        memcpy(task->st, data, sizeof(struct stat));
> >>>> +    }
> >>>> +    if (task->co) {
> >>>> +        task->bh = qemu_bh_new(nfs_co_generic_bh_cb, task);
> >>>> +        qemu_bh_schedule(task->bh);
> >>>> +    }
> >>>> +}
> >>>> +
> >>>> +static int coroutine_fn nfs_co_readv(BlockDriverState *bs,
> >>>> +                                     int64_t sector_num, int nb_sectors,
> >>>> +                                     QEMUIOVector *iov)
> >>>> +{
> >>>> +    NFSClient *client = bs->opaque;
> >>>> +    NFSRPC task;
> >>>> +
> >>>> +    nfs_co_init_task(client, &task);
> >>>> +    task.iov = iov;
> >>>> +
> >>>> +    if (nfs_pread_async(client->context, client->fh,
> >>>> +                        sector_num * BDRV_SECTOR_SIZE,
> >>>> +                        nb_sectors * BDRV_SECTOR_SIZE,
> >>>> +                        nfs_co_generic_cb, &task) != 0) {
> >>>> +        return -ENOMEM;
> >>>> +    }
> >>>> +
> >>>> +    while (!task.complete) {
> >>>> +        nfs_set_events(client);
> >>>> +        qemu_coroutine_yield();
> >>>> +    }
> >>>> +
> >>>> +    if (task.status < 0) {
> >>>> +        return task.status;
> >>>> +    }
> >>>> +
> >>>> +    /* zero pad short reads */
> >>>> +    if (task.status < iov->size) {
> >>>> +        qemu_iovec_memset(iov, task.status, 0, iov->size - task.status);
> >>>> +    }
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static int coroutine_fn nfs_co_writev(BlockDriverState *bs,
> >>>> +                                        int64_t sector_num, int 
> >>>> nb_sectors,
> >>>> +                                        QEMUIOVector *iov)
> >>>> +{
> >>>> +    NFSClient *client = bs->opaque;
> >>>> +    NFSRPC 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 -ENOMEM;
> >>>> +    }
> >>>> +
> >>>> +    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;
> >>>> +    }
> >>>> +
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static int coroutine_fn nfs_co_flush(BlockDriverState *bs)
> >>>> +{
> >>>> +    NFSClient *client = bs->opaque;
> >>>> +    NFSRPC task;
> >>>> +
> >>>> +    nfs_co_init_task(client, &task);
> >>>> +
> >>>> +    if (nfs_fsync_async(client->context, client->fh, nfs_co_generic_cb,
> >>>> +                        &task) != 0) {
> >>>> +        return -ENOMEM;
> >>>> +    }
> >>>> +
> >>>> +    while (!task.complete) {
> >>>> +        nfs_set_events(client);
> >>>> +        qemu_coroutine_yield();
> >>>> +    }
> >>>> +
> >>>> +    return task.status;
> >>>> +}
> >>>> +
> >>>> +/* TODO Convert to fine grained options */
> >>>> +static QemuOptsList runtime_opts = {
> >>>> +    .name = "nfs",
> >>>> +    .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
> >>>> +    .desc = {
> >>>> +        {
> >>>> +            .name = "filename",
> >>>> +            .type = QEMU_OPT_STRING,
> >>>> +            .help = "URL to the NFS file",
> >>>> +        },
> >>>> +        { /* end of list */ }
> >>>> +    },
> >>>> +};
> >>>> +
> >>>> +static void nfs_client_close(NFSClient *client)
> >>>> +{
> >>>> +    if (client->context) {
> >>>> +        if (client->fh) {
> >>>> +            nfs_close(client->context, client->fh);
> >>>> +        }
> >>>> +        qemu_aio_set_fd_handler(nfs_get_fd(client->context), NULL, 
> >>>> NULL, NULL);
> >>>> +        nfs_destroy_context(client->context);
> >>>> +    }
> >>>> +    memset(client, 0, sizeof(NFSClient));
> >>>> +}
> >>>> +
> >>>> +static void nfs_file_close(BlockDriverState *bs)
> >>>> +{
> >>>> +    NFSClient *client = bs->opaque;
> >>>> +    nfs_client_close(client);
> >>>> +}
> >>>> +
> >>>> +static int64_t nfs_.cilclient_open(NFSClient *client, const char 
> >>>> *filename,
> >>>> +                               int flags, Error **errp)
> >>>> +{
> >>>> +    int ret = -EINVAL, i;
> >>>> +    struct stat st;
> >>>> +    URI *uri;
> >>>> +    QueryParams *qp = NULL;
> >>>> +    char *file = NULL, *strp = NULL;
> >>>> +
> >>>> +    uri = uri_parse(filename);
> >>>> +    if (!uri) {
> >>>> +        error_setg(errp, "Invalid URL specified");
> >>>> +        goto fail;
> >>> Should this be goto out since we don't have done nfs_init_context yet ?
> >>>> +    }
> >>>> +    strp = strrchr(uri->path, '/');
> >>>> +    if (strp == NULL) {
> >>>> +        error_setg(errp, "Invalid URL specified");
> >>>> +        goto fail;
> >>> goto out ?
> >>>> +    }
> >>>> +    file = g_strdup(strp);
> >>>> +    *strp = 0;
> >>>> +
> >>>> +    client->context = nfs_init_context();
> >>>> +    if (client->context == NULL) {
> >>>> +        error_setg(errp, "Failed to init NFS context");
> >>>> +        goto fail;
> >>>> +    }
> >>>> +
> >>>> +    qp = query_params_parse(uri->query);
> >>>> +    for (i = 0; i < qp->n; i++) {
> >>>> +        if (!qp->p[i].value) {
> >>>> +            error_setg(errp, "Value for NFS parameter expected: %s",
> >>>> +                       qp->p[i].name);
> >>>> +            goto fail;
> >>>> +        }
> >>>> +        if (!strncmp(qp->p[i].name, "uid", 3)) {
> >>>> +            nfs_set_uid(client->context, atoi(qp->p[i].value));
> >>>> +        } else if (!strncmp(qp->p[i].name, "gid", 3)) {
> >>>> +            nfs_set_gid(client->context, atoi(qp->p[i].value));
> >>>> +        } else if (!strncmp(qp->p[i].name, "tcp-syncnt", 10)) {
> >>>> +            nfs_set_tcp_syncnt(client->context, atoi(qp->p[i].value));
> >>>> +        } else {
> >>>> +            error_setg(errp, "Unknown NFS parameter name: %s",
> >>>> +                       qp->p[i].name);
> >>>> +            goto fail;
> >>>> +        }
> >>>> +    }
> >>>> +
> >>>> +    ret = nfs_mount(client->context, uri->server, uri->path);
> >>>> +    if (ret < 0) {
> >>>> +        error_setg(errp, "Failed to mount nfs share: %s",
> >>>> +                   nfs_get_error(client->context));
> >>>> +        goto fail;
> >>>> +    }
> >>>> +
> >>>> +    if (flags & O_CREAT) {
> >>>> +        ret = nfs_creat(client->context, file, 0600, &client->fh);
> >>>> +        if (ret < 0) {
> >>>> +            error_setg(errp, "Failed to create file: %s",
> >>>> +                       nfs_get_error(client->context));
> >>>> +            goto fail;
> >>>> +        }
> >>>> +    } else {
> >>>> +        ret = nfs_open(client->context, file, flags, &client->fh);
> >>>> +        if (ret < 0) {
> >>>> +            error_setg(errp, "Failed to open file : %s",
> >>>> +                       nfs_get_error(client->context));
> >>>> +            goto fail;
> >>>> +        }
> >>>> +    }
> >>>> +
> >>>> +    ret = nfs_fstat(client->context, client->fh, &st);
> >>>> +    if (ret < 0) {
> >>>> +        error_setg(errp, "Failed to fstat file: %s",
> >>>> +                   nfs_get_error(client->context));
> >>>> +        goto fail;
> >>>> +    }
> >>>> +
> >>>> +    ret = DIV_ROUND_UP(st.st_size, BDRV_SECTOR_SIZE);
> >>>> +    client->has_zero_init = S_ISREG(st.st_mode);
> >>>> +    goto out;
> >>>> +fail:
> >>>> +    nfs_client_close(client);
> >>>> +out:
> >>>> +    if (qp) {
> >>>> +        query_params_free(qp);
> >>>> +    }
> >>>> +    uri_free(uri);
> >>>> +    g_free(file);
> >>>> +    return ret;
> >>>> +}
> >>>> +
> >>>> +static int nfs_file_open(BlockDriverState *bs, QDict *options, int 
> >>>> flags,
> >>>> +                         Error **errp) {
> >>>> +    NFSClient *client = bs->opaque;
> >>>> +    int64_t ret;
> >>>> +    QemuOpts *opts;
> >>>> +    Error *local_err = NULL;
> >>>> +
> >>>> +    opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
> >>>> +    qemu_opts_absorb_qdict(opts, options, &local_err);
> >>>> +    if (error_is_set(&local_err)) {
> >>>> +        qerror_report_err(local_err);
> >>> I have seen more usage of error_propagate(errp, local_err); in QEMU code.
> >>> Maybe I am missing the point.
> >>> 
> >>>> +        error_free(local_err);
> >>>> +        return -EINVAL;
> >>>> +    }
> >>>> +    ret = nfs_client_open(client, qemu_opt_get(opts, "filename"),
> >>>> +                          (flags & BDRV_O_RDWR) ? O_RDWR : O_RDONLY,
> >>>> +                          errp);
> >>>> +    if (ret < 0) {
> >>>> +        return ret;
> >>>> +    }
> >>>> +    bs->total_sectors = ret;
> >>>> +    return 0;
> >>>> +}
> >>>> +
> >>>> +static int nfs_file_create(const char *url, QEMUOptionParameter 
> >>>> *options,
> >>>> +                         Error **errp)
> >>>> +{
> >>>> +    int ret = 0;
> >>>> +    int64_t total_size = 0;
> >>>> +    NFSClient *client = g_malloc0(sizeof(NFSClient));
> >>>> +
> >>>> +    /* Read out options */
> >>>> +    while (options && options->name) {
> >>>> +        if (!strcmp(options->name, "size")) {
> >>>> +            total_size = options->value.n;
> >>>> +        }
> >>>> +        options++;
> >>>> +    }
> >>>> +
> >>>> +    ret = nfs_client_open(client, url, O_CREAT, errp);
> >>>> +    if (ret < 0) {
> >>>> +        goto out;
> >>>> +    }
> >>>> +    ret = nfs_ftruncate(client->context, client->fh, total_size);
> >>>> +out:
> >>> Should the out: label be after nfs_client_close(client); since the code 
> >>> will
> >>> jump to it on nfs_client_open failure ?
> >> You are right, but it doesn't hurt since you can call nfs_client_close 
> >> multiple
> >> times.
> > 
> > Will you send another revision addressing the other comments?
> 
> Sorry, which other comments are you referring to?

I replied to Benoit's email hilighting his questions which were not
addressed.

> Have you been able to test the patch without the bad commit?

Waiting for a final version to test.

Stefan