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

[Peter Lieven]

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?

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

BR,
Peter