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block: JSON filenames and relative backing files

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When using a relative backing file name, qemu needs to know the
directory of the top image file. For JSON filenames, such a directory
cannot be easily determined (e.g. how do you determine the directory of
a qcow2 BDS directly on top of a quorum BDS?). Therefore, do not allow
relative filenames for the backing file of BDSs only having a JSON
filename.

Furthermore, BDS::exact_filename should be used whenever possible. If
BDS::filename is not equal to BDS::exact_filename, the former will
always be a JSON object.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2014-11-26 17:20:26 +01:00 committed by Stefan Hajnoczi
parent 0a82855a1a
commit 9f07429e88
3 changed files with 31 additions and 9 deletions
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28
block.c
View File

@ -305,19 +305,28 @@ void path_combine(char *dest, int dest_size,
void bdrv_get_full_backing_filename_from_filename(const char *backed, void bdrv_get_full_backing_filename_from_filename(const char *backed,
const char *backing, const char *backing,
char *dest, size_t sz) char *dest, size_t sz,
Error **errp)
{ {
if (backing[0] == '\0' || path_has_protocol(backing)) { if (backing[0] == '\0' || path_has_protocol(backing) ||
path_is_absolute(backing))
{
pstrcpy(dest, sz, backing); pstrcpy(dest, sz, backing);
} else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
error_setg(errp, "Cannot use relative backing file names for '%s'",
backed);
} else { } else {
path_combine(dest, sz, backed, backing); path_combine(dest, sz, backed, backing);
} }
} }
void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz) void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz,
Error **errp)
{ {
bdrv_get_full_backing_filename_from_filename(bs->filename, bs->backing_file, char *backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
dest, sz);
bdrv_get_full_backing_filename_from_filename(backed, bs->backing_file,
dest, sz, errp);
} }
void bdrv_register(BlockDriver *bdrv) void bdrv_register(BlockDriver *bdrv)
@ -1225,7 +1234,14 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
QDECREF(options); QDECREF(options);
goto free_exit; goto free_exit;
} else { } else {
bdrv_get_full_backing_filename(bs, backing_filename, PATH_MAX); bdrv_get_full_backing_filename(bs, backing_filename, PATH_MAX,
&local_err);
if (local_err) {
ret = -EINVAL;
error_propagate(errp, local_err);
QDECREF(options);
goto free_exit;
}
} }
if (!bs->drv || !bs->drv->supports_backing) { if (!bs->drv || !bs->drv->supports_backing) {

7
block/qapi.c
View File

@ -214,7 +214,12 @@ void bdrv_query_image_info(BlockDriverState *bs,
info->backing_filename = g_strdup(backing_filename); info->backing_filename = g_strdup(backing_filename);
info->has_backing_filename = true; info->has_backing_filename = true;
bdrv_get_full_backing_filename(bs, backing_filename2, bdrv_get_full_backing_filename(bs, backing_filename2,
sizeof(backing_filename2)); sizeof(backing_filename2), &err);
if (err) {
error_propagate(errp, err);
qapi_free_ImageInfo(info);
return;
}
if (strcmp(backing_filename, backing_filename2) != 0) { if (strcmp(backing_filename, backing_filename2) != 0) {
info->full_backing_filename = info->full_backing_filename =

5
include/block/block.h
View File

@ -396,10 +396,11 @@ const char *bdrv_get_encrypted_filename(BlockDriverState *bs);
void bdrv_get_backing_filename(BlockDriverState *bs, void bdrv_get_backing_filename(BlockDriverState *bs,
char *filename, int filename_size); char *filename, int filename_size);
void bdrv_get_full_backing_filename(BlockDriverState *bs, void bdrv_get_full_backing_filename(BlockDriverState *bs,
char *dest, size_t sz); char *dest, size_t sz, Error **errp);
void bdrv_get_full_backing_filename_from_filename(const char *backed, void bdrv_get_full_backing_filename_from_filename(const char *backed,
const char *backing, const char *backing,
char *dest, size_t sz); char *dest, size_t sz,
Error **errp);
int bdrv_is_snapshot(BlockDriverState *bs); int bdrv_is_snapshot(BlockDriverState *bs);
int path_has_protocol(const char *path); int path_has_protocol(const char *path);