Re: [Qemu-devel] [PATCHv2] block: add native support for NFS

[Peter Lieven]

> Am 17.12.2013 um 17:53 schrieb ronnie sahlberg <address@hidden>:
> 
> NFSTask
> 
> Task is a very scsi-ish term. Maybe RPC is better ?
> 
> NFSrpc ?

will change it in v3

> 
> 
> 
>> On Tue, Dec 17, 2013 at 1:15 AM, Peter Lieven <address@hidden> 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://<host>/<export>/<filename>
>> 
>> 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 <address@hidden>
>> ---
>> 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
>> 
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index c19133f..f53d184 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -899,6 +899,11 @@ 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 f43ecbc..aa8eaf9 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 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..006b8cc
>> --- /dev/null
>> +++ b/block/nfs.c
>> @@ -0,0 +1,419 @@
>> +/*
>> + * QEMU Block driver for native access to files on NFS shares
>> + *
>> + * Copyright (c) 2013 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 "sysemu/sysemu.h"
>> +
>> +#include <nfsc/libnfs-zdr.h>
>> +#include <nfsc/libnfs.h>
>> +#include <nfsc/libnfs-raw.h>
>> +#include <nfsc/libnfs-raw-mount.h>
>> +
>> +typedef struct nfsclient {
>> +    struct nfs_context *context;
>> +    struct nfsfh *fh;
>> +    int events;
>> +    bool has_zero_init;
>> +    int64_t allocated_file_size;
>> +} NFSClient;
>> +
>> +typedef struct NFSTask {
>> +    int status;
>> +    int complete;
>> +    QEMUIOVector *iov;
>> +    Coroutine *co;
>> +    QEMUBH *bh;
>> +} NFSTask;
>> +
>> +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, NFSTask *Task)
>> +{
>> +    *Task = (NFSTask) {
>> +        .co         = qemu_coroutine_self(),
>> +    };
>> +}
>> +
>> +static void nfs_co_generic_bh_cb(void *opaque)
>> +{
>> +    NFSTask *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)
>> +{
>> +    NFSTask *Task = private_data;
>> +    Task->complete = 1;
>> +    Task->status = status;
>> +    if (Task->status > 0 && Task->iov) {
>> +        if (Task->status <= Task->iov->size) {
>> +            qemu_iovec_from_buf(Task->iov, 0, data, Task->status);
>> +        } else {
>> +            Task->status = -EIO;
>> +        }
>> +    }
>> +    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;
>> +    NFSTask 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 -EIO;
>> +    }
>> +
>> +    while (!task.complete) {
>> +        nfs_set_events(client);
>> +        qemu_coroutine_yield();
>> +    }
>> +
>> +    if (task.status < 0) {
>> +        return 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;
>> +    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;
>> +    }
>> +
>> +    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);
>> +    /* 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;
>> +    return 0;
>> +}
>> +
>> +static int coroutine_fn nfs_co_flush(BlockDriverState *bs)
>> +{
>> +    NFSClient *client = bs->opaque;
>> +    NFSTask task;
>> +
>> +    nfs_co_init_task(client, &task);
>> +
>> +    if (nfs_fsync_async(client->context, client->fh, nfs_co_generic_cb,
>> +                        &task) != 0) {
>> +        return -EIO;
>> +    }
>> +
>> +    while (!task.complete) {
>> +        nfs_set_events(client);
>> +        qemu_coroutine_yield();
>> +    }
>> +
>> +    return task.status;
>> +}
>> +
>> +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_file_close(BlockDriverState *bs)
>> +{
>> +    NFSClient *client = bs->opaque;
>> +    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 int nfs_file_open_common(BlockDriverState *bs, QDict *options, int 
>> flags,
>> +                         int open_flags, Error **errp)
>> +{
>> +    NFSClient *client = bs->opaque;
>> +    const char *filename;
>> +    int ret = 0;
>> +    QemuOpts *opts;
>> +    Error *local_err = NULL;
>> +    char *server = NULL, *path = NULL, *file = NULL, *strp;
>> +    struct stat st;
>> +
>> +    opts = qemu_opts_create_nofail(&runtime_opts);
>> +    qemu_opts_absorb_qdict(opts, options, &local_err);
>> +    if (error_is_set(&local_err)) {
>> +        qerror_report_err(local_err);
>> +        error_free(local_err);
>> +        ret = -EINVAL;
>> +        goto fail;
>> +    }
>> +
>> +    filename = qemu_opt_get(opts, "filename");
>> +
>> +    client->context = nfs_init_context();
>> +
>> +    if (client->context == NULL) {
>> +        error_setg(errp, "Failed to init NFS context");
>> +        ret = -EINVAL;
>> +        goto fail;
>> +    }
>> +
>> +    if (strlen(filename) <= 6) {
>> +        error_setg(errp, "Invalid server in URL");
>> +        ret = -EINVAL;
>> +        goto fail;
>> +    }
>> +
>> +    server = g_strdup(filename + 6);
>> +    if (server[0] == '/' || server[0] == '\0') {
>> +        error_setg(errp, "Invalid server in URL");
>> +        ret = -EINVAL;
>> +        goto fail;
>> +    }
>> +    strp = strchr(server, '/');
>> +    if (strp == NULL) {
>> +        error_setg(errp, "Invalid URL specified.\n");
>> +        ret = -EINVAL;
>> +        goto fail;
>> +    }
>> +    path = g_strdup(strp);
>> +    *strp = 0;
>> +    strp = strrchr(path, '/');
>> +    if (strp == NULL) {
>> +        error_setg(errp, "Invalid URL specified.\n");
>> +        ret = -EINVAL;
>> +        goto fail;
>> +    }
>> +    file = g_strdup(strp);
>> +    *strp = 0;
>> +
>> +    ret = nfs_mount(client->context, server, path);
>> +    if (ret < 0) {
>> +        error_setg(errp, "Failed to mount nfs share: %s",
>> +                    nfs_get_error(client->context));
>> +        goto fail;
>> +    }
>> +
>> +    if (open_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 {
>> +        open_flags = (flags & BDRV_O_RDWR) ? O_RDWR : O_RDONLY;
>> +        ret = nfs_open(client->context, file, open_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;
>> +    }
>> +
>> +    /* TODO allow reading beyond EOF */
>> +    bs->total_sectors = DIV_ROUND_UP(st.st_size, BDRV_SECTOR_SIZE);
>> +    client->has_zero_init = S_ISREG(st.st_mode);
>> +    client->allocated_file_size = st.st_blocks * st.st_blksize;
>> +    goto out;
>> +fail:
>> +    nfs_file_close(bs);
>> +out:
>> +    g_free(server);
>> +    g_free(path);
>> +    g_free(file);
>> +    return ret;
>> +}
>> +
>> +static int nfs_file_open(BlockDriverState *bs, QDict *options, int flags,
>> +                         Error **errp) {
>> +    return nfs_file_open_common(bs, options, flags, 0, errp);
>> +}
>> +
>> +static int nfs_file_create(const char *filename, QEMUOptionParameter 
>> *options,
>> +                         Error **errp)
>> +{
>> +    int ret = 0;
>> +    int64_t total_size = 0;
>> +    BlockDriverState *bs;
>> +    NFSClient *client = NULL;
>> +    QDict *bs_options;
>> +
>> +    bs = bdrv_new("");
>> +
>> +    /* Read out options */
>> +    while (options && options->name) {
>> +        if (!strcmp(options->name, "size")) {
>> +            total_size = options->value.n;
>> +        }
>> +        options++;
>> +    }
>> +
>> +    bs->opaque = g_malloc0(sizeof(NFSClient));
>> +    client = bs->opaque;
>> +
>> +    bs_options = qdict_new();
>> +    qdict_put(bs_options, "filename", qstring_from_str(filename));
>> +    ret = nfs_file_open_common(bs, bs_options, 0, O_CREAT, NULL);
>> +    QDECREF(bs_options);
>> +    if (ret < 0) {
>> +        goto out;
>> +    }
>> +    ret = nfs_ftruncate(client->context, client->fh, total_size);
>> +out:
>> +    nfs_file_close(bs);
>> +    g_free(bs->opaque);
>> +    bs->opaque = NULL;
>> +    bdrv_unref(bs);
>> +    return ret;
>> +}
>> +
>> +static int nfs_has_zero_init(BlockDriverState *bs)
>> +{
>> +    NFSClient *client = bs->opaque;
>> +    return client->has_zero_init;
>> +}
>> +
>> +static int64_t nfs_get_allocated_file_size(BlockDriverState *bs)
>> +{
>> +    NFSClient *client = bs->opaque;
>> +    return client->allocated_file_size;
>> +}
>> +
>> +static BlockDriver bdrv_nfs = {
>> +    .format_name     = "nfs",
>> +    .protocol_name   = "nfs",
>> +
>> +    .instance_size   = sizeof(NFSClient),
>> +    .bdrv_needs_filename = true,
>> +    .bdrv_has_zero_init = nfs_has_zero_init,
>> +    .bdrv_get_allocated_file_size = nfs_get_allocated_file_size,
>> +
>> +    .bdrv_file_open  = nfs_file_open,
>> +    .bdrv_close      = nfs_file_close,
>> +    .bdrv_create     = nfs_file_create,
>> +
>> +    .bdrv_co_readv         = nfs_co_readv,
>> +    .bdrv_co_writev        = nfs_co_writev,
>> +    .bdrv_co_flush_to_disk = nfs_co_flush,
>> +};
>> +
>> +static void nfs_block_init(void)
>> +{
>> +    bdrv_register(&bdrv_nfs);
>> +}
>> +
>> +block_init(nfs_block_init);
>> diff --git a/configure b/configure
>> index 8144d9f..6c9e47a 100755
>> --- a/configure
>> +++ b/configure
>> @@ -250,6 +250,7 @@ vss_win32_sdk=""
>> win_sdk="no"
>> want_tools="yes"
>> libiscsi=""
>> +libnfs=""
>> coroutine=""
>> coroutine_pool=""
>> seccomp=""
>> @@ -833,6 +834,10 @@ for opt do
>>   ;;
>>   --enable-libiscsi) libiscsi="yes"
>>   ;;
>> +  --disable-libnfs) libnfs="no"
>> +  ;;
>> +  --enable-libnfs) libnfs="yes"
>> +  ;;
>>   --enable-profiler) profiler="yes"
>>   ;;
>>   --disable-cocoa) cocoa="no"
>> @@ -1202,6 +1207,8 @@ echo "  --enable-spice           enable spice"
>> echo "  --enable-rbd             enable building the rados block device 
>> (rbd)"
>> echo "  --disable-libiscsi       disable iscsi support"
>> echo "  --enable-libiscsi        enable iscsi support"
>> +echo "  --disable-libnfs         disable nfs support"
>> +echo "  --enable-libnfs          enable nfs support"
>> echo "  --disable-smartcard-nss  disable smartcard nss support"
>> echo "  --enable-smartcard-nss   enable smartcard nss support"
>> echo "  --disable-libusb         disable libusb (for usb passthrough)"
>> @@ -3050,6 +3057,32 @@ EOF
>>   fi
>> fi
>> 
>> +##########################################
>> +# Do we have libnfs
>> +if test "$libnfs" != "no" ; then
>> +  cat > $TMPC << EOF
>> +#include <nfsc/libnfs-zdr.h>
>> +#include <nfsc/libnfs.h>
>> +#include <nfsc/libnfs-raw.h>
>> +#include <nfsc/libnfs-raw-mount.h>
>> +int main(void) {
>> +    nfs_init_context();
>> +    nfs_pread_async(0,0,0,0,0,0);
>> +    nfs_pwrite_async(0,0,0,0,0,0,0);
>> +    nfs_fstat(0,0,0);
>> +    return 0;
>> +    }
>> +EOF
>> +  if compile_prog "-Werror" "-lnfs" ; then
>> +    libnfs="yes"
>> +    LIBS="$LIBS -lnfs"
>> +  else
>> +    if test "$libnfs" = "yes" ; then
>> +      feature_not_found "libnfs"
>> +    fi
>> +    libnfs="no"
>> +  fi
>> +fi
>> 
>> ##########################################
>> # Do we need libm
>> @@ -3777,6 +3810,7 @@ echo "libusb            $libusb"
>> echo "usb net redir     $usb_redir"
>> echo "GLX support       $glx"
>> echo "libiscsi support  $libiscsi"
>> +echo "libnfs support    $libnfs"
>> echo "build guest agent $guest_agent"
>> echo "QGA VSS support   $guest_agent_with_vss"
>> echo "seccomp support   $seccomp"
>> @@ -4107,6 +4141,10 @@ if test "$libiscsi" = "yes" ; then
>>   echo "CONFIG_LIBISCSI=y" >> $config_host_mak
>> fi
>> 
>> +if test "$libnfs" = "yes" ; then
>> +  echo "CONFIG_LIBNFS=y" >> $config_host_mak
>> +fi
>> +
>> if test "$seccomp" = "yes"; then
>>   echo "CONFIG_SECCOMP=y" >> $config_host_mak
>> fi
>> --
>> 1.7.9.5
>> 
>>