qemu/block/nfs.c
Peter Lieven 18a8056e0b block/nfs: cache allocated filesize for read-only files
If the file is readonly its not expected to grow so
save the blocking call to nfs_fstat_async and use
the value saved at connection time. Also important
the monitor (and thus the main loop) will not hang
if block device info is queried and the NFS share
is unresponsive.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1440671441-7978-1-git-send-email-pl@kamp.de
Signed-off-by: Jeff Cody <jcody@redhat.com>
2015-09-25 08:37:07 -04:00

553 lines
15 KiB
C

/*
* QEMU Block driver for native access to files on NFS shares
*
* Copyright (c) 2014 Peter Lieven <pl@kamp.de>
*
* 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>
#define QEMU_NFS_MAX_READAHEAD_SIZE 1048576
typedef struct NFSClient {
struct nfs_context *context;
struct nfsfh *fh;
int events;
bool has_zero_init;
AioContext *aio_context;
blkcnt_t st_blocks;
} NFSClient;
typedef struct NFSRPC {
int ret;
int complete;
QEMUIOVector *iov;
struct stat *st;
Coroutine *co;
QEMUBH *bh;
NFSClient *client;
} 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) {
aio_set_fd_handler(client->aio_context,
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(),
.client = client,
};
}
static void nfs_co_generic_bh_cb(void *opaque)
{
NFSRPC *task = opaque;
task->complete = 1;
qemu_bh_delete(task->bh);
qemu_coroutine_enter(task->co, NULL);
}
static void
nfs_co_generic_cb(int ret, struct nfs_context *nfs, void *data,
void *private_data)
{
NFSRPC *task = private_data;
task->ret = ret;
if (task->ret > 0 && task->iov) {
if (task->ret <= task->iov->size) {
qemu_iovec_from_buf(task->iov, 0, data, task->ret);
} else {
task->ret = -EIO;
}
}
if (task->ret == 0 && task->st) {
memcpy(task->st, data, sizeof(struct stat));
}
if (task->ret < 0) {
error_report("NFS Error: %s", nfs_get_error(nfs));
}
if (task->co) {
task->bh = aio_bh_new(task->client->aio_context,
nfs_co_generic_bh_cb, task);
qemu_bh_schedule(task->bh);
} else {
task->complete = 1;
}
}
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.ret < 0) {
return task.ret;
}
/* zero pad short reads */
if (task.ret < iov->size) {
qemu_iovec_memset(iov, task.ret, 0, iov->size - task.ret);
}
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_try_malloc(nb_sectors * BDRV_SECTOR_SIZE);
if (nb_sectors && buf == NULL) {
return -ENOMEM;
}
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.ret != nb_sectors * BDRV_SECTOR_SIZE) {
return task.ret < 0 ? task.ret : -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.ret;
}
/* 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_detach_aio_context(BlockDriverState *bs)
{
NFSClient *client = bs->opaque;
aio_set_fd_handler(client->aio_context,
nfs_get_fd(client->context),
NULL, NULL, NULL);
client->events = 0;
}
static void nfs_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
NFSClient *client = bs->opaque;
client->aio_context = new_context;
nfs_set_events(client);
}
static void nfs_client_close(NFSClient *client)
{
if (client->context) {
if (client->fh) {
nfs_close(client->context, client->fh);
}
aio_set_fd_handler(client->aio_context,
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_client_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;
}
if (!uri->server) {
error_setg(errp, "Invalid URL specified");
goto fail;
}
strp = strrchr(uri->path, '/');
if (strp == NULL) {
error_setg(errp, "Invalid URL specified");
goto fail;
}
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++) {
unsigned long long val;
if (!qp->p[i].value) {
error_setg(errp, "Value for NFS parameter expected: %s",
qp->p[i].name);
goto fail;
}
if (parse_uint_full(qp->p[i].value, &val, 0)) {
error_setg(errp, "Illegal value for NFS parameter: %s",
qp->p[i].name);
goto fail;
}
if (!strcmp(qp->p[i].name, "uid")) {
nfs_set_uid(client->context, val);
} else if (!strcmp(qp->p[i].name, "gid")) {
nfs_set_gid(client->context, val);
} else if (!strcmp(qp->p[i].name, "tcp-syncnt")) {
nfs_set_tcp_syncnt(client->context, val);
#ifdef LIBNFS_FEATURE_READAHEAD
} else if (!strcmp(qp->p[i].name, "readahead")) {
if (val > QEMU_NFS_MAX_READAHEAD_SIZE) {
error_report("NFS Warning: Truncating NFS readahead"
" size to %d", QEMU_NFS_MAX_READAHEAD_SIZE);
val = QEMU_NFS_MAX_READAHEAD_SIZE;
}
nfs_set_readahead(client->context, val);
#endif
} 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->st_blocks = st.st_blocks;
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;
client->aio_context = bdrv_get_aio_context(bs);
opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto out;
}
ret = nfs_client_open(client, qemu_opt_get(opts, "filename"),
(flags & BDRV_O_RDWR) ? O_RDWR : O_RDONLY,
errp);
if (ret < 0) {
goto out;
}
bs->total_sectors = ret;
ret = 0;
out:
qemu_opts_del(opts);
return ret;
}
static QemuOptsList nfs_create_opts = {
.name = "nfs-create-opts",
.head = QTAILQ_HEAD_INITIALIZER(nfs_create_opts.head),
.desc = {
{
.name = BLOCK_OPT_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Virtual disk size"
},
{ /* end of list */ }
}
};
static int nfs_file_create(const char *url, QemuOpts *opts, Error **errp)
{
int ret = 0;
int64_t total_size = 0;
NFSClient *client = g_new0(NFSClient, 1);
client->aio_context = qemu_get_aio_context();
/* Read out options */
total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
BDRV_SECTOR_SIZE);
ret = nfs_client_open(client, url, O_CREAT, errp);
if (ret < 0) {
goto out;
}
ret = nfs_ftruncate(client->context, client->fh, total_size);
nfs_client_close(client);
out:
g_free(client);
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;
NFSRPC task = {0};
struct stat st;
if (bdrv_is_read_only(bs) &&
!(bs->open_flags & BDRV_O_NOCACHE)) {
return client->st_blocks * 512;
}
task.st = &st;
if (nfs_fstat_async(client->context, client->fh, nfs_co_generic_cb,
&task) != 0) {
return -ENOMEM;
}
while (!task.complete) {
nfs_set_events(client);
aio_poll(client->aio_context, true);
}
return (task.ret < 0 ? task.ret : st.st_blocks * 512);
}
static int nfs_file_truncate(BlockDriverState *bs, int64_t offset)
{
NFSClient *client = bs->opaque;
return nfs_ftruncate(client->context, client->fh, offset);
}
/* Note that this will not re-establish a connection with the NFS server
* - it is effectively a NOP. */
static int nfs_reopen_prepare(BDRVReopenState *state,
BlockReopenQueue *queue, Error **errp)
{
NFSClient *client = state->bs->opaque;
struct stat st;
int ret = 0;
if (state->flags & BDRV_O_RDWR && bdrv_is_read_only(state->bs)) {
error_setg(errp, "Cannot open a read-only mount as read-write");
return -EACCES;
}
/* Update cache for read-only reopens */
if (!(state->flags & BDRV_O_RDWR)) {
ret = nfs_fstat(client->context, client->fh, &st);
if (ret < 0) {
error_setg(errp, "Failed to fstat file: %s",
nfs_get_error(client->context));
return ret;
}
client->st_blocks = st.st_blocks;
}
return 0;
}
static BlockDriver bdrv_nfs = {
.format_name = "nfs",
.protocol_name = "nfs",
.instance_size = sizeof(NFSClient),
.bdrv_needs_filename = true,
.create_opts = &nfs_create_opts,
.bdrv_has_zero_init = nfs_has_zero_init,
.bdrv_get_allocated_file_size = nfs_get_allocated_file_size,
.bdrv_truncate = nfs_file_truncate,
.bdrv_file_open = nfs_file_open,
.bdrv_close = nfs_file_close,
.bdrv_create = nfs_file_create,
.bdrv_reopen_prepare = nfs_reopen_prepare,
.bdrv_co_readv = nfs_co_readv,
.bdrv_co_writev = nfs_co_writev,
.bdrv_co_flush_to_disk = nfs_co_flush,
.bdrv_detach_aio_context = nfs_detach_aio_context,
.bdrv_attach_aio_context = nfs_attach_aio_context,
};
static void nfs_block_init(void)
{
bdrv_register(&bdrv_nfs);
}
block_init(nfs_block_init);