qemu/block/throttle.c
Markus Armbruster af175e85f9 error: Eliminate error_propagate() with Coccinelle, part 2
When all we do with an Error we receive into a local variable is
propagating to somewhere else, we can just as well receive it there
right away.  The previous commit did that with a Coccinelle script I
consider fairly trustworthy.  This commit uses the same script with
the matching of return taken out, i.e. we convert

    if (!foo(..., &err)) {
        ...
        error_propagate(errp, err);
        ...
    }

to

    if (!foo(..., errp)) {
        ...
        ...
    }

This is unsound: @err could still be read between afterwards.  I don't
know how to express "no read of @err without an intervening write" in
Coccinelle.  Instead, I manually double-checked for uses of @err.

Suboptimal line breaks tweaked manually.  qdev_realize() simplified
further to placate scripts/checkpatch.pl.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-36-armbru@redhat.com>
2020-07-10 15:18:08 +02:00

268 lines
8.2 KiB
C

/*
* QEMU block throttling filter driver infrastructure
*
* Copyright (c) 2017 Manos Pitsidianakis
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 or
* (at your option) version 3 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "block/throttle-groups.h"
#include "qemu/module.h"
#include "qemu/option.h"
#include "qemu/throttle-options.h"
#include "qapi/error.h"
static QemuOptsList throttle_opts = {
.name = "throttle",
.head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head),
.desc = {
{
.name = QEMU_OPT_THROTTLE_GROUP_NAME,
.type = QEMU_OPT_STRING,
.help = "Name of the throttle group",
},
{ /* end of list */ }
},
};
/*
* If this function succeeds then the throttle group name is stored in
* @group and must be freed by the caller.
* If there's an error then @group remains unmodified.
*/
static int throttle_parse_options(QDict *options, char **group, Error **errp)
{
int ret;
const char *group_name;
QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort);
if (!qemu_opts_absorb_qdict(opts, options, errp)) {
ret = -EINVAL;
goto fin;
}
group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME);
if (!group_name) {
error_setg(errp, "Please specify a throttle group");
ret = -EINVAL;
goto fin;
} else if (!throttle_group_exists(group_name)) {
error_setg(errp, "Throttle group '%s' does not exist", group_name);
ret = -EINVAL;
goto fin;
}
*group = g_strdup(group_name);
ret = 0;
fin:
qemu_opts_del(opts);
return ret;
}
static int throttle_open(BlockDriverState *bs, QDict *options,
int flags, Error **errp)
{
ThrottleGroupMember *tgm = bs->opaque;
char *group;
int ret;
bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
false, errp);
if (!bs->file) {
return -EINVAL;
}
bs->supported_write_flags = bs->file->bs->supported_write_flags |
BDRV_REQ_WRITE_UNCHANGED;
bs->supported_zero_flags = bs->file->bs->supported_zero_flags |
BDRV_REQ_WRITE_UNCHANGED;
ret = throttle_parse_options(options, &group, errp);
if (ret == 0) {
/* Register membership to group with name group_name */
throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
g_free(group);
}
return ret;
}
static void throttle_close(BlockDriverState *bs)
{
ThrottleGroupMember *tgm = bs->opaque;
throttle_group_unregister_tgm(tgm);
}
static int64_t throttle_getlength(BlockDriverState *bs)
{
return bdrv_getlength(bs->file->bs);
}
static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
ThrottleGroupMember *tgm = bs->opaque;
throttle_group_co_io_limits_intercept(tgm, bytes, false);
return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
}
static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
ThrottleGroupMember *tgm = bs->opaque;
throttle_group_co_io_limits_intercept(tgm, bytes, true);
return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
}
static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int bytes,
BdrvRequestFlags flags)
{
ThrottleGroupMember *tgm = bs->opaque;
throttle_group_co_io_limits_intercept(tgm, bytes, true);
return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
}
static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,
int64_t offset, int bytes)
{
ThrottleGroupMember *tgm = bs->opaque;
throttle_group_co_io_limits_intercept(tgm, bytes, true);
return bdrv_co_pdiscard(bs->file, offset, bytes);
}
static int throttle_co_flush(BlockDriverState *bs)
{
return bdrv_co_flush(bs->file->bs);
}
static void throttle_detach_aio_context(BlockDriverState *bs)
{
ThrottleGroupMember *tgm = bs->opaque;
throttle_group_detach_aio_context(tgm);
}
static void throttle_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
ThrottleGroupMember *tgm = bs->opaque;
throttle_group_attach_aio_context(tgm, new_context);
}
static int throttle_reopen_prepare(BDRVReopenState *reopen_state,
BlockReopenQueue *queue, Error **errp)
{
int ret;
char *group = NULL;
assert(reopen_state != NULL);
assert(reopen_state->bs != NULL);
ret = throttle_parse_options(reopen_state->options, &group, errp);
reopen_state->opaque = group;
return ret;
}
static void throttle_reopen_commit(BDRVReopenState *reopen_state)
{
BlockDriverState *bs = reopen_state->bs;
ThrottleGroupMember *tgm = bs->opaque;
char *group = reopen_state->opaque;
assert(group);
if (strcmp(group, throttle_group_get_name(tgm))) {
throttle_group_unregister_tgm(tgm);
throttle_group_register_tgm(tgm, group, bdrv_get_aio_context(bs));
}
g_free(reopen_state->opaque);
reopen_state->opaque = NULL;
}
static void throttle_reopen_abort(BDRVReopenState *reopen_state)
{
g_free(reopen_state->opaque);
reopen_state->opaque = NULL;
}
static void coroutine_fn throttle_co_drain_begin(BlockDriverState *bs)
{
ThrottleGroupMember *tgm = bs->opaque;
if (atomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
throttle_group_restart_tgm(tgm);
}
}
static void coroutine_fn throttle_co_drain_end(BlockDriverState *bs)
{
ThrottleGroupMember *tgm = bs->opaque;
assert(tgm->io_limits_disabled);
atomic_dec(&tgm->io_limits_disabled);
}
static const char *const throttle_strong_runtime_opts[] = {
QEMU_OPT_THROTTLE_GROUP_NAME,
NULL
};
static BlockDriver bdrv_throttle = {
.format_name = "throttle",
.instance_size = sizeof(ThrottleGroupMember),
.bdrv_open = throttle_open,
.bdrv_close = throttle_close,
.bdrv_co_flush = throttle_co_flush,
.bdrv_child_perm = bdrv_default_perms,
.bdrv_getlength = throttle_getlength,
.bdrv_co_preadv = throttle_co_preadv,
.bdrv_co_pwritev = throttle_co_pwritev,
.bdrv_co_pwrite_zeroes = throttle_co_pwrite_zeroes,
.bdrv_co_pdiscard = throttle_co_pdiscard,
.bdrv_attach_aio_context = throttle_attach_aio_context,
.bdrv_detach_aio_context = throttle_detach_aio_context,
.bdrv_reopen_prepare = throttle_reopen_prepare,
.bdrv_reopen_commit = throttle_reopen_commit,
.bdrv_reopen_abort = throttle_reopen_abort,
.bdrv_co_block_status = bdrv_co_block_status_from_file,
.bdrv_co_drain_begin = throttle_co_drain_begin,
.bdrv_co_drain_end = throttle_co_drain_end,
.is_filter = true,
.strong_runtime_opts = throttle_strong_runtime_opts,
};
static void bdrv_throttle_init(void)
{
bdrv_register(&bdrv_throttle);
}
block_init(bdrv_throttle_init);