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fuchsia / third_party / qemu / 17e1e49814096a3daaa8e5a73acd56a0f30bdc18 / . / block.c
blob: 2e3905c99e8c5ab46aed09171bade5b94847c9cc [file] [log] [blame]
/*
* QEMU System Emulator block driver
*
* Copyright (c) 2003 Fabrice Bellard
*
* 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 "qemu/osdep.h"
#include "block/trace.h"
#include "block/block_int.h"
#include "block/blockjob.h"
#include "block/nbd.h"
#include "block/qdict.h"
#include "qemu/error-report.h"
#include "module_block.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
#include "qapi/error.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qjson.h"
#include "qapi/qmp/qnull.h"
#include "qapi/qmp/qstring.h"
#include "qapi/qobject-output-visitor.h"
#include "qapi/qapi-visit-block-core.h"
#include "sysemu/block-backend.h"
#include "sysemu/sysemu.h"
#include "qemu/notify.h"
#include "qemu/option.h"
#include "qemu/coroutine.h"
#include "block/qapi.h"
#include "qemu/timer.h"
#include "qemu/cutils.h"
#include "qemu/id.h"
#ifdef CONFIG_BSD
#include <sys/ioctl.h>
#include <sys/queue.h>
#ifndef __DragonFly__
#include <sys/disk.h>
#endif
#endif
#ifdef _WIN32
#include <windows.h>
#endif
#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states =
QTAILQ_HEAD_INITIALIZER(all_bdrv_states);
static QLIST_HEAD(, BlockDriver) bdrv_drivers =
QLIST_HEAD_INITIALIZER(bdrv_drivers);
static BlockDriverState *bdrv_open_inherit(const char *filename,
const char *reference,
QDict *options, int flags,
BlockDriverState *parent,
const BdrvChildRole *child_role,
Error **errp);
/* If non-zero, use only whitelisted block drivers */
static int use_bdrv_whitelist;
#ifdef _WIN32
static int is_windows_drive_prefix(const char *filename)
{
return (((filename[0] >= 'a' && filename[0] <= 'z') ||
(filename[0] >= 'A' && filename[0] <= 'Z')) &&
filename[1] == ':');
}
int is_windows_drive(const char *filename)
{
if (is_windows_drive_prefix(filename) &&
filename[2] == '\0')
return 1;
if (strstart(filename, "\\\\.\\", NULL) ||
strstart(filename, "//./", NULL))
return 1;
return 0;
}
#endif
size_t bdrv_opt_mem_align(BlockDriverState *bs)
{
if (!bs || !bs->drv) {
/* page size or 4k (hdd sector size) should be on the safe side */
return MAX(4096, qemu_real_host_page_size);
}
return bs->bl.opt_mem_alignment;
}
size_t bdrv_min_mem_align(BlockDriverState *bs)
{
if (!bs || !bs->drv) {
/* page size or 4k (hdd sector size) should be on the safe side */
return MAX(4096, qemu_real_host_page_size);
}
return bs->bl.min_mem_alignment;
}
/* check if the path starts with "<protocol>:" */
int path_has_protocol(const char *path)
{
const char *p;
#ifdef _WIN32
if (is_windows_drive(path) ||
is_windows_drive_prefix(path)) {
return 0;
}
p = path + strcspn(path, ":/\\");
#else
p = path + strcspn(path, ":/");
#endif
return *p == ':';
}
int path_is_absolute(const char *path)
{
#ifdef _WIN32
/* specific case for names like: "\\.\d:" */
if (is_windows_drive(path) || is_windows_drive_prefix(path)) {
return 1;
}
return (*path == '/' || *path == '\\');
#else
return (*path == '/');
#endif
}
/* if filename is absolute, just return its duplicate. Otherwise, build a
path to it by considering it is relative to base_path. URL are
supported. */
char *path_combine(const char *base_path, const char *filename)
{
const char *protocol_stripped = NULL;
const char *p, *p1;
char *result;
int len;
if (path_is_absolute(filename)) {
return g_strdup(filename);
}
if (path_has_protocol(base_path)) {
protocol_stripped = strchr(base_path, ':');
if (protocol_stripped) {
protocol_stripped++;
}
}
p = protocol_stripped ?: base_path;
p1 = strrchr(base_path, '/');
#ifdef _WIN32
{
const char *p2;
p2 = strrchr(base_path, '\\');
if (!p1 || p2 > p1) {
p1 = p2;
}
}
#endif
if (p1) {
p1++;
} else {
p1 = base_path;
}
if (p1 > p) {
p = p1;
}
len = p - base_path;
result = g_malloc(len + strlen(filename) + 1);
memcpy(result, base_path, len);
strcpy(result + len, filename);
return result;
}
/*
* Helper function for bdrv_parse_filename() implementations to remove optional
* protocol prefixes (especially "file:") from a filename and for putting the
* stripped filename into the options QDict if there is such a prefix.
*/
void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
QDict *options)
{
if (strstart(filename, prefix, &filename)) {
/* Stripping the explicit protocol prefix may result in a protocol
* prefix being (wrongly) detected (if the filename contains a colon) */
if (path_has_protocol(filename)) {
QString *fat_filename;
/* This means there is some colon before the first slash; therefore,
* this cannot be an absolute path */
assert(!path_is_absolute(filename));
/* And we can thus fix the protocol detection issue by prefixing it
* by "./" */
fat_filename = qstring_from_str("./");
qstring_append(fat_filename, filename);
assert(!path_has_protocol(qstring_get_str(fat_filename)));
qdict_put(options, "filename", fat_filename);
} else {
/* If no protocol prefix was detected, we can use the shortened
* filename as-is */
qdict_put_str(options, "filename", filename);
}
}
}
/* Returns whether the image file is opened as read-only. Note that this can
* return false and writing to the image file is still not possible because the
* image is inactivated. */
bool bdrv_is_read_only(BlockDriverState *bs)
{
return bs->read_only;
}
int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
bool ignore_allow_rdw, Error **errp)
{
/* Do not set read_only if copy_on_read is enabled */
if (bs->copy_on_read && read_only) {
error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
bdrv_get_device_or_node_name(bs));
return -EINVAL;
}
/* Do not clear read_only if it is prohibited */
if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
!ignore_allow_rdw)
{
error_setg(errp, "Node '%s' is read only",
bdrv_get_device_or_node_name(bs));
return -EPERM;
}
return 0;
}
/*
* Called by a driver that can only provide a read-only image.
*
* Returns 0 if the node is already read-only or it could switch the node to
* read-only because BDRV_O_AUTO_RDONLY is set.
*
* Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set
* or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg
* is not NULL, it is used as the error message for the Error object.
*/
int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
Error **errp)
{
int ret = 0;
if (!(bs->open_flags & BDRV_O_RDWR)) {
return 0;
}
if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
goto fail;
}
ret = bdrv_can_set_read_only(bs, true, false, NULL);
if (ret < 0) {
goto fail;
}
bs->read_only = true;
bs->open_flags &= ~BDRV_O_RDWR;
return 0;
fail:
error_setg(errp, "%s", errmsg ?: "Image is read-only");
return -EACCES;
}
/*
* If @backing is empty, this function returns NULL without setting
* @errp. In all other cases, NULL will only be returned with @errp
* set.
*
* Therefore, a return value of NULL without @errp set means that
* there is no backing file; if @errp is set, there is one but its
* absolute filename cannot be generated.
*/
char *bdrv_get_full_backing_filename_from_filename(const char *backed,
const char *backing,
Error **errp)
{
if (backing[0] == '\0') {
return NULL;
} else if (path_has_protocol(backing) || path_is_absolute(backing)) {
return g_strdup(backing);
} else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
error_setg(errp, "Cannot use relative backing file names for '%s'",
backed);
return NULL;
} else {
return path_combine(backed, backing);
}
}
/*
* If @filename is empty or NULL, this function returns NULL without
* setting @errp. In all other cases, NULL will only be returned with
* @errp set.
*/
static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
const char *filename, Error **errp)
{
char *dir, *full_name;
if (!filename || filename[0] == '\0') {
return NULL;
} else if (path_has_protocol(filename) || path_is_absolute(filename)) {
return g_strdup(filename);
}
dir = bdrv_dirname(relative_to, errp);
if (!dir) {
return NULL;
}
full_name = g_strconcat(dir, filename, NULL);
g_free(dir);
return full_name;
}
char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
{
return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
}
void bdrv_register(BlockDriver *bdrv)
{
assert(bdrv->format_name);
QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
}
BlockDriverState *bdrv_new(void)
{
BlockDriverState *bs;
int i;
bs = g_new0(BlockDriverState, 1);
QLIST_INIT(&bs->dirty_bitmaps);
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
QLIST_INIT(&bs->op_blockers[i]);
}
notifier_with_return_list_init(&bs->before_write_notifiers);
qemu_co_mutex_init(&bs->reqs_lock);
qemu_mutex_init(&bs->dirty_bitmap_mutex);
bs->refcnt = 1;
bs->aio_context = qemu_get_aio_context();
qemu_co_queue_init(&bs->flush_queue);
for (i = 0; i < bdrv_drain_all_count; i++) {
bdrv_drained_begin(bs);
}
QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
return bs;
}
static BlockDriver *bdrv_do_find_format(const char *format_name)
{
BlockDriver *drv1;
QLIST_FOREACH(drv1, &bdrv_drivers, list) {
if (!strcmp(drv1->format_name, format_name)) {
return drv1;
}
}
return NULL;
}
BlockDriver *bdrv_find_format(const char *format_name)
{
BlockDriver *drv1;
int i;
drv1 = bdrv_do_find_format(format_name);
if (drv1) {
return drv1;
}
/* The driver isn't registered, maybe we need to load a module */
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
if (!strcmp(block_driver_modules[i].format_name, format_name)) {
block_module_load_one(block_driver_modules[i].library_name);
break;
}
}
return bdrv_do_find_format(format_name);
}
static int bdrv_format_is_whitelisted(const char *format_name, bool read_only)
{
static const char *whitelist_rw[] = {
CONFIG_BDRV_RW_WHITELIST
};
static const char *whitelist_ro[] = {
CONFIG_BDRV_RO_WHITELIST
};
const char **p;
if (!whitelist_rw[0] && !whitelist_ro[0]) {
return 1; /* no whitelist, anything goes */
}
for (p = whitelist_rw; *p; p++) {
if (!strcmp(format_name, *p)) {
return 1;
}
}
if (read_only) {
for (p = whitelist_ro; *p; p++) {
if (!strcmp(format_name, *p)) {
return 1;
}
}
}
return 0;
}
int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
{
return bdrv_format_is_whitelisted(drv->format_name, read_only);
}
bool bdrv_uses_whitelist(void)
{
return use_bdrv_whitelist;
}
typedef struct CreateCo {
BlockDriver *drv;
char *filename;
QemuOpts *opts;
int ret;
Error *err;
} CreateCo;
static void coroutine_fn bdrv_create_co_entry(void *opaque)
{
Error *local_err = NULL;
int ret;
CreateCo *cco = opaque;
assert(cco->drv);
ret = cco->drv->bdrv_co_create_opts(cco->drv,
cco->filename, cco->opts, &local_err);
error_propagate(&cco->err, local_err);
cco->ret = ret;
}
int bdrv_create(BlockDriver *drv, const char* filename,
QemuOpts *opts, Error **errp)
{
int ret;
Coroutine *co;
CreateCo cco = {
.drv = drv,
.filename = g_strdup(filename),
.opts = opts,
.ret = NOT_DONE,
.err = NULL,
};
if (!drv->bdrv_co_create_opts) {
error_setg(errp, "Driver '%s' does not support image creation", drv->format_name);
ret = -ENOTSUP;
goto out;
}
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_create_co_entry(&cco);
} else {
co = qemu_coroutine_create(bdrv_create_co_entry, &cco);
qemu_coroutine_enter(co);
while (cco.ret == NOT_DONE) {
aio_poll(qemu_get_aio_context(), true);
}
}
ret = cco.ret;
if (ret < 0) {
if (cco.err) {
error_propagate(errp, cco.err);
} else {
error_setg_errno(errp, -ret, "Could not create image");
}
}
out:
g_free(cco.filename);
return ret;
}
/**
* Helper function for bdrv_create_file_fallback(): Resize @blk to at
* least the given @minimum_size.
*
* On success, return @blk's actual length.
* Otherwise, return -errno.
*/
static int64_t create_file_fallback_truncate(BlockBackend *blk,
int64_t minimum_size, Error **errp)
{
Error *local_err = NULL;
int64_t size;
int ret;
ret = blk_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, &local_err);
if (ret < 0 && ret != -ENOTSUP) {
error_propagate(errp, local_err);
return ret;
}
size = blk_getlength(blk);
if (size < 0) {
error_free(local_err);
error_setg_errno(errp, -size,
"Failed to inquire the new image file's length");
return size;
}
if (size < minimum_size) {
/* Need to grow the image, but we failed to do that */
error_propagate(errp, local_err);
return -ENOTSUP;
}
error_free(local_err);
local_err = NULL;
return size;
}
/**
* Helper function for bdrv_create_file_fallback(): Zero the first
* sector to remove any potentially pre-existing image header.
*/
static int create_file_fallback_zero_first_sector(BlockBackend *blk,
int64_t current_size,
Error **errp)
{
int64_t bytes_to_clear;
int ret;
bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE);
if (bytes_to_clear) {
ret = blk_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
if (ret < 0) {
error_setg_errno(errp, -ret,
"Failed to clear the new image's first sector");
return ret;
}
}
return 0;
}
/**
* Simple implementation of bdrv_co_create_opts for protocol drivers
* which only support creation via opening a file
* (usually existing raw storage device)
*/
int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv,
const char *filename,
QemuOpts *opts,
Error **errp)
{
BlockBackend *blk;
QDict *options;
int64_t size = 0;
char *buf = NULL;
PreallocMode prealloc;
Error *local_err = NULL;
int ret;
size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
PREALLOC_MODE_OFF, &local_err);
g_free(buf);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
if (prealloc != PREALLOC_MODE_OFF) {
error_setg(errp, "Unsupported preallocation mode '%s'",
PreallocMode_str(prealloc));
return -ENOTSUP;
}
options = qdict_new();
qdict_put_str(options, "driver", drv->format_name);
blk = blk_new_open(filename, NULL, options,
BDRV_O_RDWR | BDRV_O_RESIZE, errp);
if (!blk) {
error_prepend(errp, "Protocol driver '%s' does not support image "
"creation, and opening the image failed: ",
drv->format_name);
return -EINVAL;
}
size = create_file_fallback_truncate(blk, size, errp);
if (size < 0) {
ret = size;
goto out;
}
ret = create_file_fallback_zero_first_sector(blk, size, errp);
if (ret < 0) {
goto out;
}
ret = 0;
out:
blk_unref(blk);
return ret;
}
int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp)
{
BlockDriver *drv;
drv = bdrv_find_protocol(filename, true, errp);
if (drv == NULL) {
return -ENOENT;
}
return bdrv_create(drv, filename, opts, errp);
}
int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp)
{
Error *local_err = NULL;
int ret;
assert(bs != NULL);
if (!bs->drv) {
error_setg(errp, "Block node '%s' is not opened", bs->filename);
return -ENOMEDIUM;
}
if (!bs->drv->bdrv_co_delete_file) {
error_setg(errp, "Driver '%s' does not support image deletion",
bs->drv->format_name);
return -ENOTSUP;
}
ret = bs->drv->bdrv_co_delete_file(bs, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
}
return ret;
}
/**
* Try to get @bs's logical and physical block size.
* On success, store them in @bsz struct and return 0.
* On failure return -errno.
* @bs must not be empty.
*/
int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_probe_blocksizes) {
return drv->bdrv_probe_blocksizes(bs, bsz);
} else if (drv && drv->is_filter && bs->file) {
return bdrv_probe_blocksizes(bs->file->bs, bsz);
}
return -ENOTSUP;
}
/**
* Try to get @bs's geometry (cyls, heads, sectors).
* On success, store them in @geo struct and return 0.
* On failure return -errno.
* @bs must not be empty.
*/
int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_probe_geometry) {
return drv->bdrv_probe_geometry(bs, geo);
} else if (drv && drv->is_filter && bs->file) {
return bdrv_probe_geometry(bs->file->bs, geo);
}
return -ENOTSUP;
}
/*
* Create a uniquely-named empty temporary file.
* Return 0 upon success, otherwise a negative errno value.
*/
int get_tmp_filename(char *filename, int size)
{
#ifdef _WIN32
char temp_dir[MAX_PATH];
/* GetTempFileName requires that its output buffer (4th param)
have length MAX_PATH or greater. */
assert(size >= MAX_PATH);
return (GetTempPath(MAX_PATH, temp_dir)
&& GetTempFileName(temp_dir, "qem", 0, filename)
? 0 : -GetLastError());
#else
int fd;
const char *tmpdir;
tmpdir = getenv("TMPDIR");
if (!tmpdir) {
tmpdir = "/var/tmp";
}
if (snprintf(filename, size, "%s/vl.XXXXXX", tmpdir) >= size) {
return -EOVERFLOW;
}
fd = mkstemp(filename);
if (fd < 0) {
return -errno;
}
if (close(fd) != 0) {
unlink(filename);
return -errno;
}
return 0;
#endif
}
/*
* Detect host devices. By convention, /dev/cdrom[N] is always
* recognized as a host CDROM.
*/
static BlockDriver *find_hdev_driver(const char *filename)
{
int score_max = 0, score;
BlockDriver *drv = NULL, *d;
QLIST_FOREACH(d, &bdrv_drivers, list) {
if (d->bdrv_probe_device) {
score = d->bdrv_probe_device(filename);
if (score > score_max) {
score_max = score;
drv = d;
}
}
}
return drv;
}
static BlockDriver *bdrv_do_find_protocol(const char *protocol)
{
BlockDriver *drv1;
QLIST_FOREACH(drv1, &bdrv_drivers, list) {
if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) {
return drv1;
}
}
return NULL;
}
BlockDriver *bdrv_find_protocol(const char *filename,
bool allow_protocol_prefix,
Error **errp)
{
BlockDriver *drv1;
char protocol[128];
int len;
const char *p;
int i;
/* TODO Drivers without bdrv_file_open must be specified explicitly */
/*
* XXX(hch): we really should not let host device detection
* override an explicit protocol specification, but moving this
* later breaks access to device names with colons in them.
* Thanks to the brain-dead persistent naming schemes on udev-
* based Linux systems those actually are quite common.
*/
drv1 = find_hdev_driver(filename);
if (drv1) {
return drv1;
}
if (!path_has_protocol(filename) || !allow_protocol_prefix) {
return &bdrv_file;
}
p = strchr(filename, ':');
assert(p != NULL);
len = p - filename;
if (len > sizeof(protocol) - 1)
len = sizeof(protocol) - 1;
memcpy(protocol, filename, len);
protocol[len] = '\0';
drv1 = bdrv_do_find_protocol(protocol);
if (drv1) {
return drv1;
}
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
if (block_driver_modules[i].protocol_name &&
!strcmp(block_driver_modules[i].protocol_name, protocol)) {
block_module_load_one(block_driver_modules[i].library_name);
break;
}
}
drv1 = bdrv_do_find_protocol(protocol);
if (!drv1) {
error_setg(errp, "Unknown protocol '%s'", protocol);
}
return drv1;
}
/*
* Guess image format by probing its contents.
* This is not a good idea when your image is raw (CVE-2008-2004), but
* we do it anyway for backward compatibility.
*
* @buf contains the image's first @buf_size bytes.
* @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE,
* but can be smaller if the image file is smaller)
* @filename is its filename.
*
* For all block drivers, call the bdrv_probe() method to get its
* probing score.
* Return the first block driver with the highest probing score.
*/
BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
const char *filename)
{
int score_max = 0, score;
BlockDriver *drv = NULL, *d;
QLIST_FOREACH(d, &bdrv_drivers, list) {
if (d->bdrv_probe) {
score = d->bdrv_probe(buf, buf_size, filename);
if (score > score_max) {
score_max = score;
drv = d;
}
}
}
return drv;
}
static int find_image_format(BlockBackend *file, const char *filename,
BlockDriver **pdrv, Error **errp)
{
BlockDriver *drv;
uint8_t buf[BLOCK_PROBE_BUF_SIZE];
int ret = 0;
/* Return the raw BlockDriver * to scsi-generic devices or empty drives */
if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) {
*pdrv = &bdrv_raw;
return ret;
}
ret = blk_pread(file, 0, buf, sizeof(buf));
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read image for determining its "
"format");
*pdrv = NULL;
return ret;
}
drv = bdrv_probe_all(buf, ret, filename);
if (!drv) {
error_setg(errp, "Could not determine image format: No compatible "
"driver found");
ret = -ENOENT;
}
*pdrv = drv;
return ret;
}
/**
* Set the current 'total_sectors' value
* Return 0 on success, -errno on error.
*/
int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
{
BlockDriver *drv = bs->drv;
if (!drv) {
return -ENOMEDIUM;
}
/* Do not attempt drv->bdrv_getlength() on scsi-generic devices */
if (bdrv_is_sg(bs))
return 0;
/* query actual device if possible, otherwise just trust the hint */
if (drv->bdrv_getlength) {
int64_t length = drv->bdrv_getlength(bs);
if (length < 0) {
return length;
}
hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
}
bs->total_sectors = hint;
return 0;
}
/**
* Combines a QDict of new block driver @options with any missing options taken
* from @old_options, so that leaving out an option defaults to its old value.
*/
static void bdrv_join_options(BlockDriverState *bs, QDict *options,
QDict *old_options)
{
if (bs->drv && bs->drv->bdrv_join_options) {
bs->drv->bdrv_join_options(options, old_options);
} else {
qdict_join(options, old_options, false);
}
}
static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts,
int open_flags,
Error **errp)
{
Error *local_err = NULL;
char *value = qemu_opt_get_del(opts, "detect-zeroes");
BlockdevDetectZeroesOptions detect_zeroes =
qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value,
BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err);
g_free(value);
if (local_err) {
error_propagate(errp, local_err);
return detect_zeroes;
}
if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
!(open_flags & BDRV_O_UNMAP))
{
error_setg(errp, "setting detect-zeroes to unmap is not allowed "
"without setting discard operation to unmap");
}
return detect_zeroes;
}
/**
* Set open flags for aio engine
*
* Return 0 on success, -1 if the engine specified is invalid
*/
int bdrv_parse_aio(const char *mode, int *flags)
{
if (!strcmp(mode, "threads")) {
/* do nothing, default */
} else if (!strcmp(mode, "native")) {
*flags |= BDRV_O_NATIVE_AIO;
#ifdef CONFIG_LINUX_IO_URING
} else if (!strcmp(mode, "io_uring")) {
*flags |= BDRV_O_IO_URING;
#endif
} else {
return -1;
}
return 0;
}
/**
* Set open flags for a given discard mode
*
* Return 0 on success, -1 if the discard mode was invalid.
*/
int bdrv_parse_discard_flags(const char *mode, int *flags)
{
*flags &= ~BDRV_O_UNMAP;
if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) {
/* do nothing */
} else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) {
*flags |= BDRV_O_UNMAP;
} else {
return -1;
}
return 0;
}
/**
* Set open flags for a given cache mode
*
* Return 0 on success, -1 if the cache mode was invalid.
*/
int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough)
{
*flags &= ~BDRV_O_CACHE_MASK;
if (!strcmp(mode, "off") || !strcmp(mode, "none")) {
*writethrough = false;
*flags |= BDRV_O_NOCACHE;
} else if (!strcmp(mode, "directsync")) {
*writethrough = true;
*flags |= BDRV_O_NOCACHE;
} else if (!strcmp(mode, "writeback")) {
*writethrough = false;
} else if (!strcmp(mode, "unsafe")) {
*writethrough = false;
*flags |= BDRV_O_NO_FLUSH;
} else if (!strcmp(mode, "writethrough")) {
*writethrough = true;
} else {
return -1;
}
return 0;
}
static char *bdrv_child_get_parent_desc(BdrvChild *c)
{
BlockDriverState *parent = c->opaque;
return g_strdup(bdrv_get_device_or_node_name(parent));
}
static void bdrv_child_cb_drained_begin(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
bdrv_do_drained_begin_quiesce(bs, NULL, false);
}
static bool bdrv_child_cb_drained_poll(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
return bdrv_drain_poll(bs, false, NULL, false);
}
static void bdrv_child_cb_drained_end(BdrvChild *child,
int *drained_end_counter)
{
BlockDriverState *bs = child->opaque;
bdrv_drained_end_no_poll(bs, drained_end_counter);
}
static void bdrv_child_cb_attach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
bdrv_apply_subtree_drain(child, bs);
}
static void bdrv_child_cb_detach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
bdrv_unapply_subtree_drain(child, bs);
}
static int bdrv_child_cb_inactivate(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
assert(bs->open_flags & BDRV_O_INACTIVE);
return 0;
}
static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore, Error **errp)
{
BlockDriverState *bs = child->opaque;
return bdrv_can_set_aio_context(bs, ctx, ignore, errp);
}
static void bdrv_child_cb_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore)
{
BlockDriverState *bs = child->opaque;
return bdrv_set_aio_context_ignore(bs, ctx, ignore);
}
/*
* Returns the options and flags that a temporary snapshot should get, based on
* the originally requested flags (the originally requested image will have
* flags like a backing file)
*/
static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
*child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY;
/* For temporary files, unconditional cache=unsafe is fine */
qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
/* Copy the read-only and discard options from the parent */
qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD);
/* aio=native doesn't work for cache.direct=off, so disable it for the
* temporary snapshot */
*child_flags &= ~BDRV_O_NATIVE_AIO;
}
/*
* Returns the options and flags that bs->file should get if a protocol driver
* is expected, based on the given options and flags for the parent BDS
*/
static void bdrv_inherited_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
int flags = parent_flags;
/* Enable protocol handling, disable format probing for bs->file */
flags |= BDRV_O_PROTOCOL;
/* If the cache mode isn't explicitly set, inherit direct and no-flush from
* the parent. */
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
/* Inherit the read-only option from the parent if it's not set */
qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
qdict_copy_default(child_options, parent_options, BDRV_OPT_AUTO_READ_ONLY);
/* Our block drivers take care to send flushes and respect unmap policy,
* so we can default to enable both on lower layers regardless of the
* corresponding parent options. */
qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
/* Clear flags that only apply to the top layer */
flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ |
BDRV_O_NO_IO);
*child_flags = flags;
}
const BdrvChildRole child_file = {
.parent_is_bds = true,
.get_parent_desc = bdrv_child_get_parent_desc,
.inherit_options = bdrv_inherited_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.attach = bdrv_child_cb_attach,
.detach = bdrv_child_cb_detach,
.inactivate = bdrv_child_cb_inactivate,
.can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
.set_aio_ctx = bdrv_child_cb_set_aio_ctx,
};
/*
* Returns the options and flags that bs->file should get if the use of formats
* (and not only protocols) is permitted for it, based on the given options and
* flags for the parent BDS
*/
static void bdrv_inherited_fmt_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
child_file.inherit_options(child_flags, child_options,
parent_flags, parent_options);
*child_flags &= ~(BDRV_O_PROTOCOL | BDRV_O_NO_IO);
}
const BdrvChildRole child_format = {
.parent_is_bds = true,
.get_parent_desc = bdrv_child_get_parent_desc,
.inherit_options = bdrv_inherited_fmt_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.attach = bdrv_child_cb_attach,
.detach = bdrv_child_cb_detach,
.inactivate = bdrv_child_cb_inactivate,
.can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
.set_aio_ctx = bdrv_child_cb_set_aio_ctx,
};
static void bdrv_backing_attach(BdrvChild *c)
{
BlockDriverState *parent = c->opaque;
BlockDriverState *backing_hd = c->bs;
assert(!parent->backing_blocker);
error_setg(&parent->backing_blocker,
"node is used as backing hd of '%s'",
bdrv_get_device_or_node_name(parent));
bdrv_refresh_filename(backing_hd);
parent->open_flags &= ~BDRV_O_NO_BACKING;
pstrcpy(parent->backing_file, sizeof(parent->backing_file),
backing_hd->filename);
pstrcpy(parent->backing_format, sizeof(parent->backing_format),
backing_hd->drv ? backing_hd->drv->format_name : "");
bdrv_op_block_all(backing_hd, parent->backing_blocker);
/* Otherwise we won't be able to commit or stream */
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
parent->backing_blocker);
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
parent->backing_blocker);
/*
* We do backup in 3 ways:
* 1. drive backup
* The target bs is new opened, and the source is top BDS
* 2. blockdev backup
* Both the source and the target are top BDSes.
* 3. internal backup(used for block replication)
* Both the source and the target are backing file
*
* In case 1 and 2, neither the source nor the target is the backing file.
* In case 3, we will block the top BDS, so there is only one block job
* for the top BDS and its backing chain.
*/
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
parent->backing_blocker);
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
parent->backing_blocker);
bdrv_child_cb_attach(c);
}
static void bdrv_backing_detach(BdrvChild *c)
{
BlockDriverState *parent = c->opaque;
assert(parent->backing_blocker);
bdrv_op_unblock_all(c->bs, parent->backing_blocker);
error_free(parent->backing_blocker);
parent->backing_blocker = NULL;
bdrv_child_cb_detach(c);
}
/*
* Returns the options and flags that bs->backing should get, based on the
* given options and flags for the parent BDS
*/
static void bdrv_backing_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
int flags = parent_flags;
/* The cache mode is inherited unmodified for backing files; except WCE,
* which is only applied on the top level (BlockBackend) */
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
/* backing files always opened read-only */
qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off");
flags &= ~BDRV_O_COPY_ON_READ;
/* snapshot=on is handled on the top layer */
flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_TEMPORARY);
*child_flags = flags;
}
static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
const char *filename, Error **errp)
{
BlockDriverState *parent = c->opaque;
bool read_only = bdrv_is_read_only(parent);
int ret;
if (read_only) {
ret = bdrv_reopen_set_read_only(parent, false, errp);
if (ret < 0) {
return ret;
}
}
ret = bdrv_change_backing_file(parent, filename,
base->drv ? base->drv->format_name : "");
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not update backing file link");
}
if (read_only) {
bdrv_reopen_set_read_only(parent, true, NULL);
}
return ret;
}
const BdrvChildRole child_backing = {
.parent_is_bds = true,
.get_parent_desc = bdrv_child_get_parent_desc,
.attach = bdrv_backing_attach,
.detach = bdrv_backing_detach,
.inherit_options = bdrv_backing_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.inactivate = bdrv_child_cb_inactivate,
.update_filename = bdrv_backing_update_filename,
.can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
.set_aio_ctx = bdrv_child_cb_set_aio_ctx,
};
static int bdrv_open_flags(BlockDriverState *bs, int flags)
{
int open_flags = flags;
/*
* Clear flags that are internal to the block layer before opening the
* image.
*/
open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL);
return open_flags;
}
static void update_flags_from_options(int *flags, QemuOpts *opts)
{
*flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY);
if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
*flags |= BDRV_O_NO_FLUSH;
}
if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) {
*flags |= BDRV_O_NOCACHE;
}
if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) {
*flags |= BDRV_O_RDWR;
}
if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) {
*flags |= BDRV_O_AUTO_RDONLY;
}
}
static void update_options_from_flags(QDict *options, int flags)
{
if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE);
}
if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) {
qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH,
flags & BDRV_O_NO_FLUSH);
}
if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) {
qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR));
}
if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) {
qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY,
flags & BDRV_O_AUTO_RDONLY);
}
}
static void bdrv_assign_node_name(BlockDriverState *bs,
const char *node_name,
Error **errp)
{
char *gen_node_name = NULL;
if (!node_name) {
node_name = gen_node_name = id_generate(ID_BLOCK);
} else if (!id_wellformed(node_name)) {
/*
* Check for empty string or invalid characters, but not if it is
* generated (generated names use characters not available to the user)
*/
error_setg(errp, "Invalid node name");
return;
}
/* takes care of avoiding namespaces collisions */
if (blk_by_name(node_name)) {
error_setg(errp, "node-name=%s is conflicting with a device id",
node_name);
goto out;
}
/* takes care of avoiding duplicates node names */
if (bdrv_find_node(node_name)) {
error_setg(errp, "Duplicate node name");
goto out;
}
/* Make sure that the node name isn't truncated */
if (strlen(node_name) >= sizeof(bs->node_name)) {
error_setg(errp, "Node name too long");
goto out;
}
/* copy node name into the bs and insert it into the graph list */
pstrcpy(bs->node_name, sizeof(bs->node_name), node_name);
QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list);
out:
g_free(gen_node_name);
}
static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv,
const char *node_name, QDict *options,
int open_flags, Error **errp)
{
Error *local_err = NULL;
int i, ret;
bdrv_assign_node_name(bs, node_name, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
bs->drv = drv;
bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
bs->opaque = g_malloc0(drv->instance_size);
if (drv->bdrv_file_open) {
assert(!drv->bdrv_needs_filename || bs->filename[0]);
ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);
} else if (drv->bdrv_open) {
ret = drv->bdrv_open(bs, options, open_flags, &local_err);
} else {
ret = 0;
}
if (ret < 0) {
if (local_err) {
error_propagate(errp, local_err);
} else if (bs->filename[0]) {
error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
} else {
error_setg_errno(errp, -ret, "Could not open image");
}
goto open_failed;
}
ret = refresh_total_sectors(bs, bs->total_sectors);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not refresh total sector count");
return ret;
}
bdrv_refresh_limits(bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
assert(bdrv_opt_mem_align(bs) != 0);
assert(bdrv_min_mem_align(bs) != 0);
assert(is_power_of_2(bs->bl.request_alignment));
for (i = 0; i < bs->quiesce_counter; i++) {
if (drv->bdrv_co_drain_begin) {
drv->bdrv_co_drain_begin(bs);
}
}
return 0;
open_failed:
bs->drv = NULL;
if (bs->file != NULL) {
bdrv_unref_child(bs, bs->file);
bs->file = NULL;
}
g_free(bs->opaque);
bs->opaque = NULL;
return ret;
}
BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name,
int flags, Error **errp)
{
BlockDriverState *bs;
int ret;
bs = bdrv_new();
bs->open_flags = flags;
bs->explicit_options = qdict_new();
bs->options = qdict_new();
bs->opaque = NULL;
update_options_from_flags(bs->options, flags);
ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp);
if (ret < 0) {
qobject_unref(bs->explicit_options);
bs->explicit_options = NULL;
qobject_unref(bs->options);
bs->options = NULL;
bdrv_unref(bs);
return NULL;
}
return bs;
}
QemuOptsList bdrv_runtime_opts = {
.name = "bdrv_common",
.head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head),
.desc = {
{
.name = "node-name",
.type = QEMU_OPT_STRING,
.help = "Node name of the block device node",
},
{
.name = "driver",
.type = QEMU_OPT_STRING,
.help = "Block driver to use for the node",
},
{
.name = BDRV_OPT_CACHE_DIRECT,
.type = QEMU_OPT_BOOL,
.help = "Bypass software writeback cache on the host",
},
{
.name = BDRV_OPT_CACHE_NO_FLUSH,
.type = QEMU_OPT_BOOL,
.help = "Ignore flush requests",
},
{
.name = BDRV_OPT_READ_ONLY,
.type = QEMU_OPT_BOOL,
.help = "Node is opened in read-only mode",
},
{
.name = BDRV_OPT_AUTO_READ_ONLY,
.type = QEMU_OPT_BOOL,
.help = "Node can become read-only if opening read-write fails",
},
{
.name = "detect-zeroes",
.type = QEMU_OPT_STRING,
.help = "try to optimize zero writes (off, on, unmap)",
},
{
.name = BDRV_OPT_DISCARD,
.type = QEMU_OPT_STRING,
.help = "discard operation (ignore/off, unmap/on)",
},
{
.name = BDRV_OPT_FORCE_SHARE,
.type = QEMU_OPT_BOOL,
.help = "always accept other writers (default: off)",
},
{ /* end of list */ }
},
};
QemuOptsList bdrv_create_opts_simple = {
.name = "simple-create-opts",
.head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head),
.desc = {
{
.name = BLOCK_OPT_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Virtual disk size"
},
{
.name = BLOCK_OPT_PREALLOC,
.type = QEMU_OPT_STRING,
.help = "Preallocation mode (allowed values: off)"
},
{ /* end of list */ }
}
};
/*
* Common part for opening disk images and files
*
* Removes all processed options from *options.
*/
static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
QDict *options, Error **errp)
{
int ret, open_flags;
const char *filename;
const char *driver_name = NULL;
const char *node_name = NULL;
const char *discard;
QemuOpts *opts;
BlockDriver *drv;
Error *local_err = NULL;
assert(bs->file == NULL);
assert(options != NULL && bs->options != options);
opts = qemu_opts_create(&bdrv_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 fail_opts;
}
update_flags_from_options(&bs->open_flags, opts);
driver_name = qemu_opt_get(opts, "driver");
drv = bdrv_find_format(driver_name);
assert(drv != NULL);
bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false);
if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) {
error_setg(errp,
BDRV_OPT_FORCE_SHARE
"=on can only be used with read-only images");
ret = -EINVAL;
goto fail_opts;
}
if (file != NULL) {
bdrv_refresh_filename(blk_bs(file));
filename = blk_bs(file)->filename;
} else {
/*
* Caution: while qdict_get_try_str() is fine, getting
* non-string types would require more care. When @options
* come from -blockdev or blockdev_add, its members are typed
* according to the QAPI schema, but when they come from
* -drive, they're all QString.
*/
filename = qdict_get_try_str(options, "filename");
}
if (drv->bdrv_needs_filename && (!filename || !filename[0])) {
error_setg(errp, "The '%s' block driver requires a file name",
drv->format_name);
ret = -EINVAL;
goto fail_opts;
}
trace_bdrv_open_common(bs, filename ?: "", bs->open_flags,
drv->format_name);
bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) {
if (!bs->read_only && bdrv_is_whitelisted(drv, true)) {
ret = bdrv_apply_auto_read_only(bs, NULL, NULL);
} else {
ret = -ENOTSUP;
}
if (ret < 0) {
error_setg(errp,
!bs->read_only && bdrv_is_whitelisted(drv, true)
? "Driver '%s' can only be used for read-only devices"
: "Driver '%s' is not whitelisted",
drv->format_name);
goto fail_opts;
}
}
/* bdrv_new() and bdrv_close() make it so */
assert(atomic_read(&bs->copy_on_read) == 0);
if (bs->open_flags & BDRV_O_COPY_ON_READ) {
if (!bs->read_only) {
bdrv_enable_copy_on_read(bs);
} else {
error_setg(errp, "Can't use copy-on-read on read-only device");
ret = -EINVAL;
goto fail_opts;
}
}
discard = qemu_opt_get(opts, BDRV_OPT_DISCARD);
if (discard != NULL) {
if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) {
error_setg(errp, "Invalid discard option");
ret = -EINVAL;
goto fail_opts;
}
}
bs->detect_zeroes =
bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto fail_opts;
}
if (filename != NULL) {
pstrcpy(bs->filename, sizeof(bs->filename), filename);
} else {
bs->filename[0] = '\0';
}
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename);
/* Open the image, either directly or using a protocol */
open_flags = bdrv_open_flags(bs, bs->open_flags);
node_name = qemu_opt_get(opts, "node-name");
assert(!drv->bdrv_file_open || file == NULL);
ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp);
if (ret < 0) {
goto fail_opts;
}
qemu_opts_del(opts);
return 0;
fail_opts:
qemu_opts_del(opts);
return ret;
}
static QDict *parse_json_filename(const char *filename, Error **errp)
{
QObject *options_obj;
QDict *options;
int ret;
ret = strstart(filename, "json:", &filename);
assert(ret);
options_obj = qobject_from_json(filename, errp);
if (!options_obj) {
error_prepend(errp, "Could not parse the JSON options: ");
return NULL;
}
options = qobject_to(QDict, options_obj);
if (!options) {
qobject_unref(options_obj);
error_setg(errp, "Invalid JSON object given");
return NULL;
}
qdict_flatten(options);
return options;
}
static void parse_json_protocol(QDict *options, const char **pfilename,
Error **errp)
{
QDict *json_options;
Error *local_err = NULL;
/* Parse json: pseudo-protocol */
if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) {
return;
}
json_options = parse_json_filename(*pfilename, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
/* Options given in the filename have lower priority than options
* specified directly */
qdict_join(options, json_options, false);
qobject_unref(json_options);
*pfilename = NULL;
}
/*
* Fills in default options for opening images and converts the legacy
* filename/flags pair to option QDict entries.
* The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a
* block driver has been specified explicitly.
*/
static int bdrv_fill_options(QDict **options, const char *filename,
int *flags, Error **errp)
{
const char *drvname;
bool protocol = *flags & BDRV_O_PROTOCOL;
bool parse_filename = false;
BlockDriver *drv = NULL;
Error *local_err = NULL;
/*
* Caution: while qdict_get_try_str() is fine, getting non-string
* types would require more care. When @options come from
* -blockdev or blockdev_add, its members are typed according to
* the QAPI schema, but when they come from -drive, they're all
* QString.
*/
drvname = qdict_get_try_str(*options, "driver");
if (drvname) {
drv = bdrv_find_format(drvname);
if (!drv) {
error_setg(errp, "Unknown driver '%s'", drvname);
return -ENOENT;
}
/* If the user has explicitly specified the driver, this choice should
* override the BDRV_O_PROTOCOL flag */
protocol = drv->bdrv_file_open;
}
if (protocol) {
*flags |= BDRV_O_PROTOCOL;
} else {
*flags &= ~BDRV_O_PROTOCOL;
}
/* Translate cache options from flags into options */
update_options_from_flags(*options, *flags);
/* Fetch the file name from the options QDict if necessary */
if (protocol && filename) {
if (!qdict_haskey(*options, "filename")) {
qdict_put_str(*options, "filename", filename);
parse_filename = true;
} else {
error_setg(errp, "Can't specify 'file' and 'filename' options at "
"the same time");
return -EINVAL;
}
}
/* Find the right block driver */
/* See cautionary note on accessing @options above */
filename = qdict_get_try_str(*options, "filename");
if (!drvname && protocol) {
if (filename) {
drv = bdrv_find_protocol(filename, parse_filename, errp);
if (!drv) {
return -EINVAL;
}
drvname = drv->format_name;
qdict_put_str(*options, "driver", drvname);
} else {
error_setg(errp, "Must specify either driver or file");
return -EINVAL;
}
}
assert(drv || !protocol);
/* Driver-specific filename parsing */
if (drv && drv->bdrv_parse_filename && parse_filename) {
drv->bdrv_parse_filename(filename, *options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
if (!drv->bdrv_needs_filename) {
qdict_del(*options, "filename");
}
}
return 0;
}
static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q,
uint64_t perm, uint64_t shared,
GSList *ignore_children,
bool *tighten_restrictions, Error **errp);
static void bdrv_child_abort_perm_update(BdrvChild *c);
static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared);
typedef struct BlockReopenQueueEntry {
bool prepared;
bool perms_checked;
BDRVReopenState state;
QTAILQ_ENTRY(BlockReopenQueueEntry) entry;
} BlockReopenQueueEntry;
/*
* Return the flags that @bs will have after the reopens in @q have
* successfully completed. If @q is NULL (or @bs is not contained in @q),
* return the current flags.
*/
static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs)
{
BlockReopenQueueEntry *entry;
if (q != NULL) {
QTAILQ_FOREACH(entry, q, entry) {
if (entry->state.bs == bs) {
return entry->state.flags;
}
}
}
return bs->open_flags;
}
/* Returns whether the image file can be written to after the reopen queue @q
* has been successfully applied, or right now if @q is NULL. */
static bool bdrv_is_writable_after_reopen(BlockDriverState *bs,
BlockReopenQueue *q)
{
int flags = bdrv_reopen_get_flags(q, bs);
return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR;
}
/*
* Return whether the BDS can be written to. This is not necessarily
* the same as !bdrv_is_read_only(bs), as inactivated images may not
* be written to but do not count as read-only images.
*/
bool bdrv_is_writable(BlockDriverState *bs)
{
return bdrv_is_writable_after_reopen(bs, NULL);
}
static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
BdrvChild *c, const BdrvChildRole *role,
BlockReopenQueue *reopen_queue,
uint64_t parent_perm, uint64_t parent_shared,
uint64_t *nperm, uint64_t *nshared)
{
assert(bs->drv && bs->drv->bdrv_child_perm);
bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
parent_perm, parent_shared,
nperm, nshared);
/* TODO Take force_share from reopen_queue */
if (child_bs && child_bs->force_share) {
*nshared = BLK_PERM_ALL;
}
}
/*
* Check whether permissions on this node can be changed in a way that
* @cumulative_perms and @cumulative_shared_perms are the new cumulative
* permissions of all its parents. This involves checking whether all necessary
* permission changes to child nodes can be performed.
*
* Will set *tighten_restrictions to true if and only if new permissions have to
* be taken or currently shared permissions are to be unshared. Otherwise,
* errors are not fatal as long as the caller accepts that the restrictions
* remain tighter than they need to be. The caller still has to abort the
* transaction.
* @tighten_restrictions cannot be used together with @q: When reopening, we may
* encounter fatal errors even though no restrictions are to be tightened. For
* example, changing a node from RW to RO will fail if the WRITE permission is
* to be kept.
*
* A call to this function must always be followed by a call to bdrv_set_perm()
* or bdrv_abort_perm_update().
*/
static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q,
uint64_t cumulative_perms,
uint64_t cumulative_shared_perms,
GSList *ignore_children,
bool *tighten_restrictions, Error **errp)
{
BlockDriver *drv = bs->drv;
BdrvChild *c;
int ret;
assert(!q || !tighten_restrictions);
if (tighten_restrictions) {
uint64_t current_perms, current_shared;
uint64_t added_perms, removed_shared_perms;
bdrv_get_cumulative_perm(bs, &current_perms, &current_shared);
added_perms = cumulative_perms & ~current_perms;
removed_shared_perms = current_shared & ~cumulative_shared_perms;
*tighten_restrictions = added_perms || removed_shared_perms;
}
/* Write permissions never work with read-only images */
if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
!bdrv_is_writable_after_reopen(bs, q))
{
if (!bdrv_is_writable_after_reopen(bs, NULL)) {
error_setg(errp, "Block node is read-only");
} else {
uint64_t current_perms, current_shared;
bdrv_get_cumulative_perm(bs, &current_perms, &current_shared);
if (current_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
error_setg(errp, "Cannot make block node read-only, there is "
"a writer on it");
} else {
error_setg(errp, "Cannot make block node read-only and create "
"a writer on it");
}
}
return -EPERM;
}
/* Check this node */
if (!drv) {
return 0;
}
if (drv->bdrv_check_perm) {
return drv->bdrv_check_perm(bs, cumulative_perms,
cumulative_shared_perms, errp);
}
/* Drivers that never have children can omit .bdrv_child_perm() */
if (!drv->bdrv_child_perm) {
assert(QLIST_EMPTY(&bs->children));
return 0;
}
/* Check all children */
QLIST_FOREACH(c, &bs->children, next) {
uint64_t cur_perm, cur_shared;
bool child_tighten_restr;
bdrv_child_perm(bs, c->bs, c, c->role, q,
cumulative_perms, cumulative_shared_perms,
&cur_perm, &cur_shared);
ret = bdrv_child_check_perm(c, q, cur_perm, cur_shared, ignore_children,
tighten_restrictions ? &child_tighten_restr
: NULL,
errp);
if (tighten_restrictions) {
*tighten_restrictions |= child_tighten_restr;
}
if (ret < 0) {
return ret;
}
}
return 0;
}
/*
* Notifies drivers that after a previous bdrv_check_perm() call, the
* permission update is not performed and any preparations made for it (e.g.
* taken file locks) need to be undone.
*
* This function recursively notifies all child nodes.
*/
static void bdrv_abort_perm_update(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
BdrvChild *c;
if (!drv) {
return;
}
if (drv->bdrv_abort_perm_update) {
drv->bdrv_abort_perm_update(bs);
}
QLIST_FOREACH(c, &bs->children, next) {
bdrv_child_abort_perm_update(c);
}
}
static void bdrv_set_perm(BlockDriverState *bs, uint64_t cumulative_perms,
uint64_t cumulative_shared_perms)
{
BlockDriver *drv = bs->drv;
BdrvChild *c;
if (!drv) {
return;
}
/* Update this node */
if (drv->bdrv_set_perm) {
drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
}
/* Drivers that never have children can omit .bdrv_child_perm() */
if (!drv->bdrv_child_perm) {
assert(QLIST_EMPTY(&bs->children));
return;
}
/* Update all children */
QLIST_FOREACH(c, &bs->children, next) {
uint64_t cur_perm, cur_shared;
bdrv_child_perm(bs, c->bs, c, c->role, NULL,
cumulative_perms, cumulative_shared_perms,
&cur_perm, &cur_shared);
bdrv_child_set_perm(c, cur_perm, cur_shared);
}
}
void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
uint64_t *shared_perm)
{
BdrvChild *c;
uint64_t cumulative_perms = 0;
uint64_t cumulative_shared_perms = BLK_PERM_ALL;
QLIST_FOREACH(c, &bs->parents, next_parent) {
cumulative_perms |= c->perm;
cumulative_shared_perms &= c->shared_perm;
}
*perm = cumulative_perms;
*shared_perm = cumulative_shared_perms;
}
static char *bdrv_child_user_desc(BdrvChild *c)
{
if (c->role->get_parent_desc) {
return c->role->get_parent_desc(c);
}
return g_strdup("another user");
}
char *bdrv_perm_names(uint64_t perm)
{
struct perm_name {
uint64_t perm;
const char *name;
} permissions[] = {
{ BLK_PERM_CONSISTENT_READ, "consistent read" },
{ BLK_PERM_WRITE, "write" },
{ BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
{ BLK_PERM_RESIZE, "resize" },
{ BLK_PERM_GRAPH_MOD, "change children" },
{ 0, NULL }
};
GString *result = g_string_sized_new(30);
struct perm_name *p;
for (p = permissions; p->name; p++) {
if (perm & p->perm) {
if (result->len > 0) {
g_string_append(result, ", ");
}
g_string_append(result, p->name);
}
}
return g_string_free(result, FALSE);
}
/*
* Checks whether a new reference to @bs can be added if the new user requires
* @new_used_perm/@new_shared_perm as its permissions. If @ignore_children is
* set, the BdrvChild objects in this list are ignored in the calculations;
* this allows checking permission updates for an existing reference.
*
* See bdrv_check_perm() for the semantics of @tighten_restrictions.
*
* Needs to be followed by a call to either bdrv_set_perm() or
* bdrv_abort_perm_update(). */
static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q,
uint64_t new_used_perm,
uint64_t new_shared_perm,
GSList *ignore_children,
bool *tighten_restrictions,
Error **errp)
{
BdrvChild *c;
uint64_t cumulative_perms = new_used_perm;
uint64_t cumulative_shared_perms = new_shared_perm;
assert(!q || !tighten_restrictions);
/* There is no reason why anyone couldn't tolerate write_unchanged */
assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED);
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (g_slist_find(ignore_children, c)) {
continue;
}
if ((new_used_perm & c->shared_perm) != new_used_perm) {
char *user = bdrv_child_user_desc(c);
char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm);
if (tighten_restrictions) {
*tighten_restrictions = true;
}
error_setg(errp, "Conflicts with use by %s as '%s', which does not "
"allow '%s' on %s",
user, c->name, perm_names, bdrv_get_node_name(c->bs));
g_free(user);
g_free(perm_names);
return -EPERM;
}
if ((c->perm & new_shared_perm) != c->perm) {
char *user = bdrv_child_user_desc(c);
char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm);
if (tighten_restrictions) {
*tighten_restrictions = true;
}
error_setg(errp, "Conflicts with use by %s as '%s', which uses "
"'%s' on %s",
user, c->name, perm_names, bdrv_get_node_name(c->bs));
g_free(user);
g_free(perm_names);
return -EPERM;
}
cumulative_perms |= c->perm;
cumulative_shared_perms &= c->shared_perm;
}
return bdrv_check_perm(bs, q, cumulative_perms, cumulative_shared_perms,
ignore_children, tighten_restrictions, errp);
}
/* Needs to be followed by a call to either bdrv_child_set_perm() or
* bdrv_child_abort_perm_update(). */
static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q,
uint64_t perm, uint64_t shared,
GSList *ignore_children,
bool *tighten_restrictions, Error **errp)
{
int ret;
ignore_children = g_slist_prepend(g_slist_copy(ignore_children), c);
ret = bdrv_check_update_perm(c->bs, q, perm, shared, ignore_children,
tighten_restrictions, errp);
g_slist_free(ignore_children);
if (ret < 0) {
return ret;
}
if (!c->has_backup_perm) {
c->has_backup_perm = true;
c->backup_perm = c->perm;
c->backup_shared_perm = c->shared_perm;
}
/*
* Note: it's OK if c->has_backup_perm was already set, as we can find the
* same child twice during check_perm procedure
*/
c->perm = perm;
c->shared_perm = shared;
return 0;
}
static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared)
{
uint64_t cumulative_perms, cumulative_shared_perms;
c->has_backup_perm = false;
c->perm = perm;
c->shared_perm = shared;
bdrv_get_cumulative_perm(c->bs, &cumulative_perms,
&cumulative_shared_perms);
bdrv_set_perm(c->bs, cumulative_perms, cumulative_shared_perms);
}
static void bdrv_child_abort_perm_update(BdrvChild *c)
{
if (c->has_backup_perm) {
c->perm = c->backup_perm;
c->shared_perm = c->backup_shared_perm;
c->has_backup_perm = false;
}
bdrv_abort_perm_update(c->bs);
}
int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
Error **errp)
{
Error *local_err = NULL;
int ret;
bool tighten_restrictions;
ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL,
&tighten_restrictions, &local_err);
if (ret < 0) {
bdrv_child_abort_perm_update(c);
if (tighten_restrictions) {
error_propagate(errp, local_err);
} else {
/*
* Our caller may intend to only loosen restrictions and
* does not expect this function to fail. Errors are not
* fatal in such a case, so we can just hide them from our
* caller.
*/
error_free(local_err);
ret = 0;
}
return ret;
}
bdrv_child_set_perm(c, perm, shared);
return 0;
}
int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp)
{
uint64_t parent_perms, parent_shared;
uint64_t perms, shared;
bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared);
bdrv_child_perm(bs, c->bs, c, c->role, NULL, parent_perms, parent_shared,
&perms, &shared);
return bdrv_child_try_set_perm(c, perms, shared, errp);
}
void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
const BdrvChildRole *role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
*nperm = perm & DEFAULT_PERM_PASSTHROUGH;
*nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
}
void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c,
const BdrvChildRole *role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
bool backing = (role == &child_backing);
assert(role == &child_backing || role == &child_file);
if (!backing) {
int flags = bdrv_reopen_get_flags(reopen_queue, bs);
/* Apart from the modifications below, the same permissions are
* forwarded and left alone as for filters */
bdrv_filter_default_perms(bs, c, role, reopen_queue, perm, shared,
&perm, &shared);
/* Format drivers may touch metadata even if the guest doesn't write */
if (bdrv_is_writable_after_reopen(bs, reopen_queue)) {
perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
}
/* bs->file always needs to be consistent because of the metadata. We
* can never allow other users to resize or write to it. */
if (!(flags & BDRV_O_NO_IO)) {
perm |= BLK_PERM_CONSISTENT_READ;
}
shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
} else {
/* We want consistent read from backing files if the parent needs it.
* No other operations are performed on backing files. */
perm &= BLK_PERM_CONSISTENT_READ;
/* If the parent can deal with changing data, we're okay with a
* writable and resizable backing file. */
/* TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too? */
if (shared & BLK_PERM_WRITE) {
shared = BLK_PERM_WRITE | BLK_PERM_RESIZE;
} else {
shared = 0;
}
shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD |
BLK_PERM_WRITE_UNCHANGED;
}
if (bs->open_flags & BDRV_O_INACTIVE) {
shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
}
*nperm = perm;
*nshared = shared;
}
uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
{
static const uint64_t permissions[] = {
[BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ,
[BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE,
[BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED,
[BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE,
[BLOCK_PERMISSION_GRAPH_MOD] = BLK_PERM_GRAPH_MOD,
};
QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX);
QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1);
assert(qapi_perm < BLOCK_PERMISSION__MAX);
return permissions[qapi_perm];
}
static void bdrv_replace_child_noperm(BdrvChild *child,
BlockDriverState *new_bs)
{
BlockDriverState *old_bs = child->bs;
int new_bs_quiesce_counter;
int drain_saldo;
assert(!child->frozen);
if (old_bs && new_bs) {
assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
}
new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0);
drain_saldo = new_bs_quiesce_counter - child->parent_quiesce_counter;
/*
* If the new child node is drained but the old one was not, flush
* all outstanding requests to the old child node.
*/
while (drain_saldo > 0 && child->role->drained_begin) {
bdrv_parent_drained_begin_single(child, true);
drain_saldo--;
}
if (old_bs) {
/* Detach first so that the recursive drain sections coming from @child
* are already gone and we only end the drain sections that came from
* elsewhere. */
if (child->role->detach) {
child->role->detach(child);
}
QLIST_REMOVE(child, next_parent);
}
child->bs = new_bs;
if (new_bs) {
QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
/*
* Detaching the old node may have led to the new node's
* quiesce_counter having been decreased. Not a problem, we
* just need to recognize this here and then invoke
* drained_end appropriately more often.
*/
assert(new_bs->quiesce_counter <= new_bs_quiesce_counter);
drain_saldo += new_bs->quiesce_counter - new_bs_quiesce_counter;
/* Attach only after starting new drained sections, so that recursive
* drain sections coming from @child don't get an extra .drained_begin
* callback. */
if (child->role->attach) {
child->role->attach(child);
}
}
/*
* If the old child node was drained but the new one is not, allow
* requests to come in only after the new node has been attached.
*/
while (drain_saldo < 0 && child->role->drained_end) {
bdrv_parent_drained_end_single(child);
drain_saldo++;
}
}
/*
* Updates @child to change its reference to point to @new_bs, including
* checking and applying the necessary permisson updates both to the old node
* and to @new_bs.
*
* NULL is passed as @new_bs for removing the reference before freeing @child.
*
* If @new_bs is not NULL, bdrv_check_perm() must be called beforehand, as this
* function uses bdrv_set_perm() to update the permissions according to the new
* reference that @new_bs gets.
*/
static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
{
BlockDriverState *old_bs = child->bs;
uint64_t perm, shared_perm;
bdrv_replace_child_noperm(child, new_bs);
/*
* Start with the new node's permissions. If @new_bs is a (direct
* or indirect) child of @old_bs, we must complete the permission
* update on @new_bs before we loosen the restrictions on @old_bs.
* Otherwise, bdrv_check_perm() on @old_bs would re-initiate
* updating the permissions of @new_bs, and thus not purely loosen
* restrictions.
*/
if (new_bs) {
bdrv_get_cumulative_perm(new_bs, &perm, &shared_perm);
bdrv_set_perm(new_bs, perm, shared_perm);
}
if (old_bs) {
/* Update permissions for old node. This is guaranteed to succeed
* because we're just taking a parent away, so we're loosening
* restrictions. */
bool tighten_restrictions;
int ret;
bdrv_get_cumulative_perm(old_bs, &perm, &shared_perm);
ret = bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL,
&tighten_restrictions, NULL);
assert(tighten_restrictions == false);
if (ret < 0) {
/* We only tried to loosen restrictions, so errors are not fatal */
bdrv_abort_perm_update(old_bs);
} else {
bdrv_set_perm(old_bs, perm, shared_perm);
}
/* When the parent requiring a non-default AioContext is removed, the
* node moves back to the main AioContext */
bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL);
}
}
/*
* This function steals the reference to child_bs from the caller.
* That reference is later dropped by bdrv_root_unref_child().
*
* On failure NULL is returned, errp is set and the reference to
* child_bs is also dropped.
*
* The caller must hold the AioContext lock @child_bs, but not that of @ctx
* (unless @child_bs is already in @ctx).
*/
BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
const char *child_name,
const BdrvChildRole *child_role,
AioContext *ctx,
uint64_t perm, uint64_t shared_perm,
void *opaque, Error **errp)
{
BdrvChild *child;
Error *local_err = NULL;
int ret;
ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL, NULL,
errp);
if (ret < 0) {
bdrv_abort_perm_update(child_bs);
bdrv_unref(child_bs);
return NULL;
}
child = g_new(BdrvChild, 1);
*child = (BdrvChild) {
.bs = NULL,
.name = g_strdup(child_name),
.role = child_role,
.perm = perm,
.shared_perm = shared_perm,
.opaque = opaque,
};
/* If the AioContexts don't match, first try to move the subtree of
* child_bs into the AioContext of the new parent. If this doesn't work,
* try moving the parent into the AioContext of child_bs instead. */
if (bdrv_get_aio_context(child_bs) != ctx) {
ret = bdrv_try_set_aio_context(child_bs, ctx, &local_err);
if (ret < 0 && child_role->can_set_aio_ctx) {
GSList *ignore = g_slist_prepend(NULL, child);
ctx = bdrv_get_aio_context(child_bs);
if (child_role->can_set_aio_ctx(child, ctx, &ignore, NULL)) {
error_free(local_err);
ret = 0;
g_slist_free(ignore);
ignore = g_slist_prepend(NULL, child);
child_role->set_aio_ctx(child, ctx, &ignore);
}
g_slist_free(ignore);
}
if (ret < 0) {
error_propagate(errp, local_err);
g_free(child);
bdrv_abort_perm_update(child_bs);
bdrv_unref(child_bs);
return NULL;
}
}
/* This performs the matching bdrv_set_perm() for the above check. */
bdrv_replace_child(child, child_bs);
return child;
}
/*
* This function transfers the reference to child_bs from the caller
* to parent_bs. That reference is later dropped by parent_bs on
* bdrv_close() or if someone calls bdrv_unref_child().
*
* On failure NULL is returned, errp is set and the reference to
* child_bs is also dropped.
*
* If @parent_bs and @child_bs are in different AioContexts, the caller must
* hold the AioContext lock for @child_bs, but not for @parent_bs.
*/
BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
BlockDriverState *child_bs,
const char *child_name,
const BdrvChildRole *child_role,
Error **errp)
{
BdrvChild *child;
uint64_t perm, shared_perm;
bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
assert(parent_bs->drv);
bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
perm, shared_perm, &perm, &shared_perm);
child = bdrv_root_attach_child(child_bs, child_name, child_role,
bdrv_get_aio_context(parent_bs),
perm, shared_perm, parent_bs, errp);
if (child == NULL) {
return NULL;
}
QLIST_INSERT_HEAD(&parent_bs->children, child, next);
return child;
}
static void bdrv_detach_child(BdrvChild *child)
{
QLIST_SAFE_REMOVE(child, next);
bdrv_replace_child(child, NULL);
g_free(child->name);
g_free(child);
}
void bdrv_root_unref_child(BdrvChild *child)
{
BlockDriverState *child_bs;
child_bs = child->bs;
bdrv_detach_child(child);
bdrv_unref(child_bs);
}
/**
* Clear all inherits_from pointers from children and grandchildren of
* @root that point to @root, where necessary.
*/
static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child)
{
BdrvChild *c;
if (child->bs->inherits_from == root) {
/*
* Remove inherits_from only when the last reference between root and
* child->bs goes away.
*/
QLIST_FOREACH(c, &root->children, next) {
if (c != child && c->bs == child->bs) {
break;
}
}
if (c == NULL) {
child->bs->inherits_from = NULL;
}
}
QLIST_FOREACH(c, &child->bs->children, next) {
bdrv_unset_inherits_from(root, c);
}
}
void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
{
if (child == NULL) {
return;
}
bdrv_unset_inherits_from(parent, child);
bdrv_root_unref_child(child);
}
static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
{
BdrvChild *c;
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (c->role->change_media) {
c->role->change_media(c, load);
}
}
}
/* Return true if you can reach parent going through child->inherits_from
* recursively. If parent or child are NULL, return false */
static bool bdrv_inherits_from_recursive(BlockDriverState *child,
BlockDriverState *parent)
{
while (child && child != parent) {
child = child->inherits_from;
}
return child != NULL;
}
/*
* Sets the backing file link of a BDS. A new reference is created; callers
* which don't need their own reference any more must call bdrv_unref().
*/
void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
Error **errp)
{
bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) &&
bdrv_inherits_from_recursive(backing_hd, bs);
if (bdrv_is_backing_chain_frozen(bs, backing_bs(bs), errp)) {
return;
}
if (backing_hd) {
bdrv_ref(backing_hd);
}
if (bs->backing) {
bdrv_unref_child(bs, bs->backing);
bs->backing = NULL;
}
if (!backing_hd) {
goto out;
}
bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_backing,
errp);
/* If backing_hd was already part of bs's backing chain, and
* inherits_from pointed recursively to bs then let's update it to
* point directly to bs (else it will become NULL). */
if (bs->backing && update_inherits_from) {
backing_hd->inherits_from = bs;
}
out:
bdrv_refresh_limits(bs, NULL);
}
/*
* Opens the backing file for a BlockDriverState if not yet open
*
* bdref_key specifies the key for the image's BlockdevRef in the options QDict.
* That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
* itself, all options starting with "${bdref_key}." are considered part of the
* BlockdevRef.
*
* TODO Can this be unified with bdrv_open_image()?
*/
int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
const char *bdref_key, Error **errp)
{
char *backing_filename = NULL;
char *bdref_key_dot;
const char *reference = NULL;
int ret = 0;
bool implicit_backing = false;
BlockDriverState *backing_hd;
QDict *options;
QDict *tmp_parent_options = NULL;
Error *local_err = NULL;
if (bs->backing != NULL) {
goto free_exit;
}
/* NULL means an empty set of options */
if (parent_options == NULL) {
tmp_parent_options = qdict_new();
parent_options = tmp_parent_options;
}
bs->open_flags &= ~BDRV_O_NO_BACKING;
bdref_key_dot = g_strdup_printf("%s.", bdref_key);
qdict_extract_subqdict(parent_options, &options, bdref_key_dot);
g_free(bdref_key_dot);
/*
* Caution: while qdict_get_try_str() is fine, getting non-string
* types would require more care. When @parent_options come from
* -blockdev or blockdev_add, its members are typed according to
* the QAPI schema, but when they come from -drive, they're all
* QString.
*/
reference = qdict_get_try_str(parent_options, bdref_key);
if (reference || qdict_haskey(options, "file.filename")) {
/* keep backing_filename NULL */
} else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
qobject_unref(options);
goto free_exit;
} else {
if (qdict_size(options) == 0) {
/* If the user specifies options that do not modify the
* backing file's behavior, we might still consider it the
* implicit backing file. But it's easier this way, and
* just specifying some of the backing BDS's options is
* only possible with -drive anyway (otherwise the QAPI
* schema forces the user to specify everything). */
implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file);
}
backing_filename = bdrv_get_full_backing_filename(bs, &local_err);
if (local_err) {
ret = -EINVAL;
error_propagate(errp, local_err);
qobject_unref(options);
goto free_exit;
}
}
if (!bs->drv || !bs->drv->supports_backing) {
ret = -EINVAL;
error_setg(errp, "Driver doesn't support backing files");
qobject_unref(options);
goto free_exit;
}
if (!reference &&
bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
qdict_put_str(options, "driver", bs->backing_format);
}
backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
&child_backing, errp);
if (!backing_hd) {
bs->open_flags |= BDRV_O_NO_BACKING;
error_prepend(errp, "Could not open backing file: ");
ret = -EINVAL;
goto free_exit;
}
if (implicit_backing) {
bdrv_refresh_filename(backing_hd);
pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
backing_hd->filename);
}
/* Hook up the backing file link; drop our reference, bs owns the
* backing_hd reference now */
bdrv_set_backing_hd(bs, backing_hd, &local_err);
bdrv_unref(backing_hd);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto free_exit;
}
qdict_del(parent_options, bdref_key);
free_exit:
g_free(backing_filename);
qobject_unref(tmp_parent_options);
return ret;
}
static BlockDriverState *
bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
BlockDriverState *parent, const BdrvChildRole *child_role,
bool allow_none, Error **errp)
{
BlockDriverState *bs = NULL;
QDict *image_options;
char *bdref_key_dot;
const char *reference;
assert(child_role != NULL);
bdref_key_dot = g_strdup_printf("%s.", bdref_key);
qdict_extract_subqdict(options, &image_options, bdref_key_dot);
g_free(bdref_key_dot);
/*
* Caution: while qdict_get_try_str() is fine, getting non-string
* types would require more care. When @options come from
* -blockdev or blockdev_add, its members are typed according to
* the QAPI schema, but when they come from -drive, they're all
* QString.
*/
reference = qdict_get_try_str(options, bdref_key);
if (!filename && !reference && !qdict_size(image_options)) {
if (!allow_none) {
error_setg(errp, "A block device must be specified for \"%s\"",
bdref_key);
}
qobject_unref(image_options);
goto done;
}
bs = bdrv_open_inherit(filename, reference, image_options, 0,
parent, child_role, errp);
if (!bs) {
goto done;
}
done:
qdict_del(options, bdref_key);
return bs;
}
/*
* Opens a disk image whose options are given as BlockdevRef in another block
* device's options.
*
* If allow_none is true, no image will be opened if filename is false and no
* BlockdevRef is given. NULL will be returned, but errp remains unset.
*
* bdrev_key specifies the key for the image's BlockdevRef in the options QDict.
* That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
* itself, all options starting with "${bdref_key}." are considered part of the
* BlockdevRef.
*
* The BlockdevRef will be removed from the options QDict.
*/
BdrvChild *bdrv_open_child(const char *filename,
QDict *options, const char *bdref_key,
BlockDriverState *parent,
const BdrvChildRole *child_role,
bool allow_none, Error **errp)
{
BlockDriverState *bs;
bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_role,
allow_none, errp);
if (bs == NULL) {
return NULL;
}
return bdrv_attach_child(parent, bs, bdref_key, child_role, errp);
}
/* TODO Future callers may need to specify parent/child_role in order for
* option inheritance to work. Existing callers use it for the root node. */
BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp)
{
BlockDriverState *bs = NULL;
Error *local_err = NULL;
QObject *obj = NULL;
QDict *qdict = NULL;
const char *reference = NULL;
Visitor *v = NULL;
if (ref->type == QTYPE_QSTRING) {
reference = ref->u.reference;
} else {
BlockdevOptions *options = &ref->u.definition;
assert(ref->type == QTYPE_QDICT);
v = qobject_output_visitor_new(&obj);
visit_type_BlockdevOptions(v, NULL, &options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto fail;
}
visit_complete(v, &obj);
qdict = qobject_to(QDict, obj);
qdict_flatten(qdict);
/* bdrv_open_inherit() defaults to the values in bdrv_flags (for
* compatibility with other callers) rather than what we want as the
* real defaults. Apply the defaults here instead. */
qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off");
qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off");
qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off");
qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off");
}
bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, errp);
obj = NULL;
fail:
qobject_unref(obj);
visit_free(v);
return bs;
}
static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
int flags,
QDict *snapshot_options,
Error **errp)
{
/* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
char *tmp_filename = g_malloc0(PATH_MAX + 1);
int64_t total_size;
QemuOpts *opts = NULL;
BlockDriverState *bs_snapshot = NULL;
Error *local_err = NULL;
int ret;
/* if snapshot, we create a temporary backing file and open it
instead of opening 'filename' directly */
/* Get the required size from the image */
total_size = bdrv_getlength(bs);
if (total_size < 0) {
error_setg_errno(errp, -total_size, "Could not get image size");
goto out;
}
/* Create the temporary image */
ret = get_tmp_filename(tmp_filename, PATH_MAX + 1);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not get temporary filename");
goto out;
}
opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0,
&error_abort);
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort);
ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp);
qemu_opts_del(opts);
if (ret < 0) {
error_prepend(errp, "Could not create temporary overlay '%s': ",
tmp_filename);
goto out;
}
/* Prepare options QDict for the temporary file */
qdict_put_str(snapshot_options, "file.driver", "file");
qdict_put_str(snapshot_options, "file.filename", tmp_filename);
qdict_put_str(snapshot_options, "driver", "qcow2");
bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp);
snapshot_options = NULL;
if (!bs_snapshot) {