diff --git a/block.c b/block.c index d86efad867..beea0274f8 100644 --- a/block.c +++ b/block.c @@ -4647,3 +4647,22 @@ int bdrv_amend_options(BlockDriverState *bs, QEMUOptionParameter *options) } return bs->drv->bdrv_amend_options(bs, options); } + +ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs) +{ + if (bs->drv->bdrv_check_ext_snapshot) { + return bs->drv->bdrv_check_ext_snapshot(bs); + } + + if (bs->file && bs->file->drv && bs->file->drv->bdrv_check_ext_snapshot) { + return bs->file->drv->bdrv_check_ext_snapshot(bs); + } + + /* external snapshots are allowed by default */ + return EXT_SNAPSHOT_ALLOWED; +} + +ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs) +{ + return EXT_SNAPSHOT_FORBIDDEN; +} diff --git a/block/blkverify.c b/block/blkverify.c index bff95d2a45..1e8e6d9961 100644 --- a/block/blkverify.c +++ b/block/blkverify.c @@ -417,6 +417,8 @@ static BlockDriver bdrv_blkverify = { .bdrv_aio_readv = blkverify_aio_readv, .bdrv_aio_writev = blkverify_aio_writev, .bdrv_aio_flush = blkverify_aio_flush, + + .bdrv_check_ext_snapshot = bdrv_check_ext_snapshot_forbidden, }; static void bdrv_blkverify_init(void) diff --git a/blockdev.c b/blockdev.c index 8c83f6f1ca..a91d5a87df 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1131,6 +1131,11 @@ static void external_snapshot_prepare(BlkTransactionState *common, } } + if (bdrv_check_ext_snapshot(state->old_bs) != EXT_SNAPSHOT_ALLOWED) { + error_set(errp, QERR_FEATURE_DISABLED, "snapshot"); + return; + } + flags = state->old_bs->open_flags; /* create new image w/backing file */ diff --git a/include/block/block.h b/include/block/block.h index 0d4d5c336c..3560deb883 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -248,6 +248,20 @@ int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix); int bdrv_amend_options(BlockDriverState *bs_new, QEMUOptionParameter *options); +/* external snapshots */ + +typedef enum { + EXT_SNAPSHOT_ALLOWED, + EXT_SNAPSHOT_FORBIDDEN, +} ExtSnapshotPerm; + +/* return EXT_SNAPSHOT_ALLOWED if external snapshot is allowed + * return EXT_SNAPSHOT_FORBIDDEN if external snapshot is forbidden + */ +ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs); +/* helper used to forbid external snapshots like in blkverify */ +ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs); + /* async block I/O */ typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector, int sector_num); diff --git a/include/block/block_int.h b/include/block/block_int.h index 17b26b2a9f..a48731d539 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -67,6 +67,12 @@ typedef struct BdrvTrackedRequest { struct BlockDriver { const char *format_name; int instance_size; + + /* if not defined external snapshots are allowed + * future block filters will query their children to build the response + */ + ExtSnapshotPerm (*bdrv_check_ext_snapshot)(BlockDriverState *bs); + int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename); int (*bdrv_probe_device)(const char *filename);