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block: Add reference parameter to bdrv_open()
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Allow bdrv_open() to handle references to existing block devices just as
bdrv_file_open() is already capable of.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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@XanClic @kevmw
XanClic authored and kevmw committed Feb 21, 2014
1 parent f67503e commit ddf5636
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Showing 10 changed files with 61 additions and 27 deletions.
44 changes: 37 additions & 7 deletions block.c
View file
Expand Up @@ -1046,7 +1046,7 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
}

if (!drv->bdrv_file_open) {
ret = bdrv_open(&bs, filename, options, flags, drv, &local_err);
ret = bdrv_open(&bs, filename, NULL, options, flags, drv, &local_err);
options = NULL;
} else {
ret = bdrv_open_common(bs, NULL, options, flags, drv, &local_err);
Expand Down Expand Up @@ -1125,7 +1125,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)

assert(bs->backing_hd == NULL);
ret = bdrv_open(&bs->backing_hd,
*backing_filename ? backing_filename : NULL, options,
*backing_filename ? backing_filename : NULL, NULL, options,
back_flags, back_drv, &local_err);
if (ret < 0) {
bs->backing_hd = NULL;
Expand Down Expand Up @@ -1206,7 +1206,7 @@ int bdrv_open_image(BlockDriverState **pbs, const char *filename,
goto done;
}

ret = bdrv_open(pbs, filename, image_options, flags, NULL, errp);
ret = bdrv_open(pbs, filename, NULL, image_options, flags, NULL, errp);
} else {
ret = bdrv_file_open(pbs, filename, reference, image_options, flags,
errp);
Expand All @@ -1227,9 +1227,14 @@ int bdrv_open_image(BlockDriverState **pbs, const char *filename,
*
* If *pbs is NULL, a new BDS will be created with a pointer to it stored there.
* If it is not NULL, the referenced BDS will be reused.
*
* The reference parameter may be used to specify an existing block device which
* should be opened. If specified, neither options nor a filename may be given,
* nor can an existing BDS be reused (that is, *pbs has to be NULL).
*/
int bdrv_open(BlockDriverState **pbs, const char *filename, QDict *options,
int flags, BlockDriver *drv, Error **errp)
int bdrv_open(BlockDriverState **pbs, const char *filename,
const char *reference, QDict *options, int flags,
BlockDriver *drv, Error **errp)
{
int ret;
/* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
Expand All @@ -1240,6 +1245,31 @@ int bdrv_open(BlockDriverState **pbs, const char *filename, QDict *options,

assert(pbs);

if (reference) {
bool options_non_empty = options ? qdict_size(options) : false;
QDECREF(options);

if (*pbs) {
error_setg(errp, "Cannot reuse an existing BDS when referencing "
"another block device");
return -EINVAL;
}

if (filename || options_non_empty) {
error_setg(errp, "Cannot reference an existing block device with "
"additional options or a new filename");
return -EINVAL;
}

bs = bdrv_lookup_bs(reference, reference, errp);
if (!bs) {
return -ENODEV;
}
bdrv_ref(bs);
*pbs = bs;
return 0;
}

if (*pbs) {
bs = *pbs;
} else {
Expand Down Expand Up @@ -1268,7 +1298,7 @@ int bdrv_open(BlockDriverState **pbs, const char *filename, QDict *options,
/* Get the required size from the image */
QINCREF(options);
bs1 = NULL;
ret = bdrv_open(&bs1, filename, options, BDRV_O_NO_BACKING,
ret = bdrv_open(&bs1, filename, NULL, options, BDRV_O_NO_BACKING,
drv, &local_err);
if (ret < 0) {
goto fail;
Expand Down Expand Up @@ -5309,7 +5339,7 @@ void bdrv_img_create(const char *filename, const char *fmt,
flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);

bs = NULL;
ret = bdrv_open(&bs, backing_file->value.s, NULL, back_flags,
ret = bdrv_open(&bs, backing_file->value.s, NULL, NULL, back_flags,
backing_drv, &local_err);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not open '%s': %s",
Expand Down
4 changes: 2 additions & 2 deletions block/qcow2.c
View file
Expand Up @@ -1553,7 +1553,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
*/
BlockDriver* drv = bdrv_find_format("qcow2");
assert(drv != NULL);
ret = bdrv_open(&bs, filename, NULL,
ret = bdrv_open(&bs, filename, NULL, NULL,
BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH, drv, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
Expand Down Expand Up @@ -1604,7 +1604,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
bs = NULL;

/* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning */
ret = bdrv_open(&bs, filename, NULL,
ret = bdrv_open(&bs, filename, NULL, NULL,
BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_BACKING,
drv, &local_err);
if (local_err) {
Expand Down
3 changes: 2 additions & 1 deletion block/vmdk.c
View file
Expand Up @@ -1756,7 +1756,8 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options,
}
if (backing_file) {
BlockDriverState *bs = NULL;
ret = bdrv_open(&bs, backing_file, NULL, BDRV_O_NO_BACKING, NULL, errp);
ret = bdrv_open(&bs, backing_file, NULL, NULL, BDRV_O_NO_BACKING, NULL,
errp);
if (ret != 0) {
goto exit;
}
Expand Down
2 changes: 1 addition & 1 deletion block/vvfat.c
View file
Expand Up @@ -2937,7 +2937,7 @@ static int enable_write_target(BDRVVVFATState *s)
}

s->qcow = NULL;
ret = bdrv_open(&s->qcow, s->qcow_filename, NULL,
ret = bdrv_open(&s->qcow, s->qcow_filename, NULL, NULL,
BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH, bdrv_qcow,
&local_err);
if (ret < 0) {
Expand Down
12 changes: 6 additions & 6 deletions blockdev.c
View file
Expand Up @@ -504,7 +504,7 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts,
bdrv_flags |= ro ? 0 : BDRV_O_RDWR;

QINCREF(bs_opts);
ret = bdrv_open(&dinfo->bdrv, file, bs_opts, bdrv_flags, drv, &error);
ret = bdrv_open(&dinfo->bdrv, file, NULL, bs_opts, bdrv_flags, drv, &error);

if (ret < 0) {
error_setg(errp, "could not open disk image %s: %s",
Expand Down Expand Up @@ -1333,7 +1333,7 @@ static void external_snapshot_prepare(BlkTransactionState *common,
/* TODO Inherit bs->options or only take explicit options with an
* extended QMP command? */
assert(state->new_bs == NULL);
ret = bdrv_open(&state->new_bs, new_image_file, options,
ret = bdrv_open(&state->new_bs, new_image_file, NULL, options,
flags | BDRV_O_NO_BACKING, drv, &local_err);
/* We will manually add the backing_hd field to the bs later */
if (ret != 0) {
Expand Down Expand Up @@ -1582,7 +1582,7 @@ static void qmp_bdrv_open_encrypted(BlockDriverState *bs, const char *filename,
Error *local_err = NULL;
int ret;

ret = bdrv_open(&bs, filename, NULL, bdrv_flags, drv, &local_err);
ret = bdrv_open(&bs, filename, NULL, NULL, bdrv_flags, drv, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
return;
Expand Down Expand Up @@ -2019,7 +2019,7 @@ void qmp_drive_backup(const char *device, const char *target,
}

target_bs = NULL;
ret = bdrv_open(&target_bs, target, NULL, flags, drv, &local_err);
ret = bdrv_open(&target_bs, target, NULL, NULL, flags, drv, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
return;
Expand Down Expand Up @@ -2162,8 +2162,8 @@ void qmp_drive_mirror(const char *device, const char *target,
* file.
*/
target_bs = NULL;
ret = bdrv_open(&target_bs, target, NULL, flags | BDRV_O_NO_BACKING, drv,
&local_err);
ret = bdrv_open(&target_bs, target, NULL, NULL, flags | BDRV_O_NO_BACKING,
drv, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
return;
Expand Down
4 changes: 2 additions & 2 deletions hw/block/xen_disk.c
View file
Expand Up @@ -813,8 +813,8 @@ static int blk_connect(struct XenDevice *xendev)
Error *local_err = NULL;
BlockDriver *drv = bdrv_find_whitelisted_format(blkdev->fileproto,
readonly);
if (bdrv_open(&blkdev->bs,
blkdev->filename, NULL, qflags, drv, &local_err) != 0)
if (bdrv_open(&blkdev->bs, blkdev->filename, NULL, NULL, qflags,
drv, &local_err) != 0)
{
xen_be_printf(&blkdev->xendev, 0, "error: %s\n",
error_get_pretty(local_err));
Expand Down
5 changes: 3 additions & 2 deletions include/block/block.h
View file
Expand Up @@ -190,8 +190,9 @@ int bdrv_open_image(BlockDriverState **pbs, const char *filename,
QDict *options, const char *bdref_key, int flags,
bool force_raw, bool allow_none, Error **errp);
int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp);
int bdrv_open(BlockDriverState **pbs, const char *filename, QDict *options,
int flags, BlockDriver *drv, Error **errp);
int bdrv_open(BlockDriverState **pbs, const char *filename,
const char *reference, QDict *options, int flags,
BlockDriver *drv, Error **errp);
BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
BlockDriverState *bs, int flags);
int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp);
Expand Down
8 changes: 4 additions & 4 deletions qemu-img.c
View file
Expand Up @@ -289,7 +289,7 @@ static BlockDriverState *bdrv_new_open(const char *filename,
drv = NULL;
}

ret = bdrv_open(&bs, filename, NULL, flags, drv, &local_err);
ret = bdrv_open(&bs, filename, NULL, NULL, flags, drv, &local_err);
if (ret < 0) {
error_report("Could not open '%s': %s", filename,
error_get_pretty(local_err));
Expand Down Expand Up @@ -2312,7 +2312,7 @@ static int img_rebase(int argc, char **argv)

bs_old_backing = bdrv_new("old_backing");
bdrv_get_backing_filename(bs, backing_name, sizeof(backing_name));
ret = bdrv_open(&bs_old_backing, backing_name, NULL, BDRV_O_FLAGS,
ret = bdrv_open(&bs_old_backing, backing_name, NULL, NULL, BDRV_O_FLAGS,
old_backing_drv, &local_err);
if (ret) {
error_report("Could not open old backing file '%s': %s",
Expand All @@ -2322,8 +2322,8 @@ static int img_rebase(int argc, char **argv)
}
if (out_baseimg[0]) {
bs_new_backing = bdrv_new("new_backing");
ret = bdrv_open(&bs_new_backing, out_baseimg, NULL, BDRV_O_FLAGS,
new_backing_drv, &local_err);
ret = bdrv_open(&bs_new_backing, out_baseimg, NULL, NULL,
BDRV_O_FLAGS, new_backing_drv, &local_err);
if (ret) {
error_report("Could not open new backing file '%s': %s",
out_baseimg, error_get_pretty(local_err));
Expand Down
4 changes: 3 additions & 1 deletion qemu-io.c
View file
Expand Up @@ -68,7 +68,9 @@ static int openfile(char *name, int flags, int growable, QDict *opts)
} else {
qemuio_bs = bdrv_new("hda");

if (bdrv_open(&qemuio_bs, name, opts, flags, NULL, &local_err) < 0) {
if (bdrv_open(&qemuio_bs, name, NULL, opts, flags, NULL, &local_err)
< 0)
{
fprintf(stderr, "%s: can't open device %s: %s\n", progname, name,
error_get_pretty(local_err));
error_free(local_err);
Expand Down
2 changes: 1 addition & 1 deletion qemu-nbd.c
View file
Expand Up @@ -597,7 +597,7 @@ int main(int argc, char **argv)

bs = bdrv_new("hda");
srcpath = argv[optind];
ret = bdrv_open(&bs, srcpath, NULL, flags, drv, &local_err);
ret = bdrv_open(&bs, srcpath, NULL, NULL, flags, drv, &local_err);
if (ret < 0) {
errno = -ret;
err(EXIT_FAILURE, "Failed to bdrv_open '%s': %s", argv[optind],
Expand Down

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