block: Allow omitting the file name when using driver-specific options
After this patch, using -drive with an empty file name continues to open the file if driver-specific options are used. If no driver-specific options are specified, the semantics stay as it was: It defines a drive without an inserted medium. In order to achieve this, bdrv_open() must be made safe to work with a NULL filename parameter. The assumption that is made is that only block drivers which implement bdrv_parse_filename() support using driver specific options and could therefore work without a filename. These drivers must make sure to cope with NULL in their implementation of .bdrv_open() (this is only NBD for now). For all other drivers, the block layer code will make sure to error out before calling into their code - they can't possibly work without a filename. Now an NBD connection can be opened like this: qemu-system-x86_64 -drive file.driver=nbd,file.port=1234,file.host=::1 Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
parent
f5866fa438
commit
c2ad1b0c46
47
block.c
47
block.c
@ -688,7 +688,11 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
|
|||||||
bdrv_enable_copy_on_read(bs);
|
bdrv_enable_copy_on_read(bs);
|
||||||
}
|
}
|
||||||
|
|
||||||
|
if (filename != NULL) {
|
||||||
pstrcpy(bs->filename, sizeof(bs->filename), filename);
|
pstrcpy(bs->filename, sizeof(bs->filename), filename);
|
||||||
|
} else {
|
||||||
|
bs->filename[0] = '\0';
|
||||||
|
}
|
||||||
|
|
||||||
if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
|
if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
|
||||||
return -ENOTSUP;
|
return -ENOTSUP;
|
||||||
@ -708,6 +712,7 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
|
|||||||
bdrv_swap(file, bs);
|
bdrv_swap(file, bs);
|
||||||
ret = 0;
|
ret = 0;
|
||||||
} else {
|
} else {
|
||||||
|
assert(drv->bdrv_parse_filename || filename != NULL);
|
||||||
ret = drv->bdrv_file_open(bs, filename, options, open_flags);
|
ret = drv->bdrv_file_open(bs, filename, options, open_flags);
|
||||||
}
|
}
|
||||||
} else {
|
} else {
|
||||||
@ -727,6 +732,7 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
|
|||||||
|
|
||||||
#ifndef _WIN32
|
#ifndef _WIN32
|
||||||
if (bs->is_temporary) {
|
if (bs->is_temporary) {
|
||||||
|
assert(filename != NULL);
|
||||||
unlink(filename);
|
unlink(filename);
|
||||||
}
|
}
|
||||||
#endif
|
#endif
|
||||||
@ -753,14 +759,9 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
|
|||||||
{
|
{
|
||||||
BlockDriverState *bs;
|
BlockDriverState *bs;
|
||||||
BlockDriver *drv;
|
BlockDriver *drv;
|
||||||
|
const char *drvname;
|
||||||
int ret;
|
int ret;
|
||||||
|
|
||||||
drv = bdrv_find_protocol(filename);
|
|
||||||
if (!drv) {
|
|
||||||
QDECREF(options);
|
|
||||||
return -ENOENT;
|
|
||||||
}
|
|
||||||
|
|
||||||
/* NULL means an empty set of options */
|
/* NULL means an empty set of options */
|
||||||
if (options == NULL) {
|
if (options == NULL) {
|
||||||
options = qdict_new();
|
options = qdict_new();
|
||||||
@ -770,7 +771,26 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
|
|||||||
bs->options = options;
|
bs->options = options;
|
||||||
options = qdict_clone_shallow(options);
|
options = qdict_clone_shallow(options);
|
||||||
|
|
||||||
if (drv->bdrv_parse_filename) {
|
/* Find the right block driver */
|
||||||
|
drvname = qdict_get_try_str(options, "driver");
|
||||||
|
if (drvname) {
|
||||||
|
drv = bdrv_find_whitelisted_format(drvname);
|
||||||
|
qdict_del(options, "driver");
|
||||||
|
} else if (filename) {
|
||||||
|
drv = bdrv_find_protocol(filename);
|
||||||
|
} else {
|
||||||
|
qerror_report(ERROR_CLASS_GENERIC_ERROR,
|
||||||
|
"Must specify either driver or file");
|
||||||
|
drv = NULL;
|
||||||
|
}
|
||||||
|
|
||||||
|
if (!drv) {
|
||||||
|
ret = -ENOENT;
|
||||||
|
goto fail;
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Parse the filename and open it */
|
||||||
|
if (drv->bdrv_parse_filename && filename) {
|
||||||
Error *local_err = NULL;
|
Error *local_err = NULL;
|
||||||
drv->bdrv_parse_filename(filename, options, &local_err);
|
drv->bdrv_parse_filename(filename, options, &local_err);
|
||||||
if (error_is_set(&local_err)) {
|
if (error_is_set(&local_err)) {
|
||||||
@ -779,6 +799,12 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
|
|||||||
ret = -EINVAL;
|
ret = -EINVAL;
|
||||||
goto fail;
|
goto fail;
|
||||||
}
|
}
|
||||||
|
} else if (!drv->bdrv_parse_filename && !filename) {
|
||||||
|
qerror_report(ERROR_CLASS_GENERIC_ERROR,
|
||||||
|
"The '%s' block driver requires a file name",
|
||||||
|
drv->format_name);
|
||||||
|
ret = -EINVAL;
|
||||||
|
goto fail;
|
||||||
}
|
}
|
||||||
|
|
||||||
ret = bdrv_open_common(bs, NULL, filename, options, flags, drv);
|
ret = bdrv_open_common(bs, NULL, filename, options, flags, drv);
|
||||||
@ -899,6 +925,13 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
|
|||||||
QEMUOptionParameter *create_options;
|
QEMUOptionParameter *create_options;
|
||||||
char backing_filename[PATH_MAX];
|
char backing_filename[PATH_MAX];
|
||||||
|
|
||||||
|
if (qdict_size(options) != 0) {
|
||||||
|
error_report("Can't use snapshot=on with driver-specific options");
|
||||||
|
ret = -EINVAL;
|
||||||
|
goto fail;
|
||||||
|
}
|
||||||
|
assert(filename != NULL);
|
||||||
|
|
||||||
/* if snapshot, we create a temporary backing file and open it
|
/* if snapshot, we create a temporary backing file and open it
|
||||||
instead of opening 'filename' directly */
|
instead of opening 'filename' directly */
|
||||||
|
|
||||||
|
@ -658,8 +658,12 @@ DriveInfo *drive_init(QemuOpts *all_opts, BlockInterfaceType block_default_type)
|
|||||||
abort();
|
abort();
|
||||||
}
|
}
|
||||||
if (!file || !*file) {
|
if (!file || !*file) {
|
||||||
|
if (qdict_size(bs_opts)) {
|
||||||
|
file = NULL;
|
||||||
|
} else {
|
||||||
return dinfo;
|
return dinfo;
|
||||||
}
|
}
|
||||||
|
}
|
||||||
if (snapshot) {
|
if (snapshot) {
|
||||||
/* always use cache=unsafe with snapshot */
|
/* always use cache=unsafe with snapshot */
|
||||||
bdrv_flags &= ~BDRV_O_CACHE_MASK;
|
bdrv_flags &= ~BDRV_O_CACHE_MASK;
|
||||||
@ -697,10 +701,10 @@ DriveInfo *drive_init(QemuOpts *all_opts, BlockInterfaceType block_default_type)
|
|||||||
if (ret < 0) {
|
if (ret < 0) {
|
||||||
if (ret == -EMEDIUMTYPE) {
|
if (ret == -EMEDIUMTYPE) {
|
||||||
error_report("could not open disk image %s: not in %s format",
|
error_report("could not open disk image %s: not in %s format",
|
||||||
file, drv->format_name);
|
file ?: dinfo->id, drv->format_name);
|
||||||
} else {
|
} else {
|
||||||
error_report("could not open disk image %s: %s",
|
error_report("could not open disk image %s: %s",
|
||||||
file, strerror(-ret));
|
file ?: dinfo->id, strerror(-ret));
|
||||||
}
|
}
|
||||||
goto err;
|
goto err;
|
||||||
}
|
}
|
||||||
|
@ -75,6 +75,9 @@ struct BlockDriver {
|
|||||||
int instance_size;
|
int instance_size;
|
||||||
int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
|
int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
|
||||||
int (*bdrv_probe_device)(const char *filename);
|
int (*bdrv_probe_device)(const char *filename);
|
||||||
|
|
||||||
|
/* Any driver implementing this callback is expected to be able to handle
|
||||||
|
* NULL file names in its .bdrv_open() implementation */
|
||||||
void (*bdrv_parse_filename)(const char *filename, QDict *options, Error **errp);
|
void (*bdrv_parse_filename)(const char *filename, QDict *options, Error **errp);
|
||||||
|
|
||||||
/* For handling image reopen for split or non-split files */
|
/* For handling image reopen for split or non-split files */
|
||||||
|
Loading…
Reference in New Issue
Block a user