diff options
| -rw-r--r-- | block.c | 65 | ||||
| -rw-r--r-- | block/blkverify.c | 2 | ||||
| -rw-r--r-- | blockdev.c | 2 | ||||
| -rw-r--r-- | include/block/block.h | 20 | ||||
| -rw-r--r-- | include/block/block_int.h | 12 |
5 files changed, 77 insertions, 24 deletions
@@ -5094,21 +5094,68 @@ int bdrv_amend_options(BlockDriverState *bs, QEMUOptionParameter *options) return bs->drv->bdrv_amend_options(bs, options); } -ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs) +/* Used to recurse on single child block filters. + * Single child block filter will store their child in bs->file. + */ +bool bdrv_generic_is_first_non_filter(BlockDriverState *bs, + BlockDriverState *candidate) { - if (bs->drv->bdrv_check_ext_snapshot) { - return bs->drv->bdrv_check_ext_snapshot(bs); + if (!bs->drv) { + return false; + } + + if (!bs->drv->authorizations[BS_IS_A_FILTER]) { + if (bs == candidate) { + return true; + } else { + return false; + } + } + + if (!bs->drv->authorizations[BS_FILTER_PASS_DOWN]) { + return false; } - if (bs->file && bs->file->drv && bs->file->drv->bdrv_check_ext_snapshot) { - return bs->file->drv->bdrv_check_ext_snapshot(bs); + if (!bs->file) { + return false; + } + + return bdrv_recurse_is_first_non_filter(bs->file, candidate); +} + +bool bdrv_recurse_is_first_non_filter(BlockDriverState *bs, + BlockDriverState *candidate) +{ + if (bs->drv && bs->drv->bdrv_recurse_is_first_non_filter) { + return bs->drv->bdrv_recurse_is_first_non_filter(bs, candidate); } - /* external snapshots are allowed by default */ - return EXT_SNAPSHOT_ALLOWED; + return bdrv_generic_is_first_non_filter(bs, candidate); } -ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs) +/* This function checks if the candidate is the first non filter bs down it's + * bs chain. Since we don't have pointers to parents it explore all bs chains + * from the top. Some filters can choose not to pass down the recursion. + */ +bool bdrv_is_first_non_filter(BlockDriverState *candidate) { - return EXT_SNAPSHOT_FORBIDDEN; + BlockDriverState *bs; + + /* walk down the bs forest recursively */ + QTAILQ_FOREACH(bs, &bdrv_states, device_list) { + bool perm; + + if (!bs->file) { + continue; + } + + perm = bdrv_recurse_is_first_non_filter(bs->file, candidate); + + /* candidate is the first non filter */ + if (perm) { + return true; + } + } + + return false; } diff --git a/block/blkverify.c b/block/blkverify.c index a2e8f5f138..cfcbcf41c3 100644 --- a/block/blkverify.c +++ b/block/blkverify.c @@ -404,7 +404,7 @@ static BlockDriver bdrv_blkverify = { .bdrv_aio_writev = blkverify_aio_writev, .bdrv_aio_flush = blkverify_aio_flush, - .bdrv_check_ext_snapshot = bdrv_check_ext_snapshot_forbidden, + .authorizations = { true, false }, }; static void bdrv_blkverify_init(void) diff --git a/blockdev.c b/blockdev.c index 2f4065e2cd..32a356eadc 100644 --- a/blockdev.c +++ b/blockdev.c @@ -1243,7 +1243,7 @@ static void external_snapshot_prepare(BlkTransactionState *common, } } - if (bdrv_check_ext_snapshot(state->old_bs) != EXT_SNAPSHOT_ALLOWED) { + if (!bdrv_is_first_non_filter(state->old_bs)) { error_set(errp, QERR_FEATURE_DISABLED, "snapshot"); return; } diff --git a/include/block/block.h b/include/block/block.h index b4a77e6cff..59d9f12ce4 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -287,16 +287,16 @@ 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); + BS_IS_A_FILTER, + BS_FILTER_PASS_DOWN, + BS_AUTHORIZATION_COUNT, +} BsAuthorization; + +bool bdrv_generic_is_first_non_filter(BlockDriverState *bs, + BlockDriverState *candidate); +bool bdrv_recurse_is_first_non_filter(BlockDriverState *bs, + BlockDriverState *candidate); +bool bdrv_is_first_non_filter(BlockDriverState *candidate); /* async block I/O */ typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector, diff --git a/include/block/block_int.h b/include/block/block_int.h index f3f518c4d2..611a955712 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -69,10 +69,16 @@ 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 + /* this table of boolean contains authorizations for the block operations */ + bool authorizations[BS_AUTHORIZATION_COUNT]; + /* for snapshots complex block filter like Quorum can implement the + * following recursive callback instead of BS_IS_A_FILTER. + * It's purpose is to recurse on the filter children while calling + * bdrv_recurse_is_first_non_filter on them. + * For a sample implementation look in the future Quorum block filter. */ - ExtSnapshotPerm (*bdrv_check_ext_snapshot)(BlockDriverState *bs); + bool (*bdrv_recurse_is_first_non_filter)(BlockDriverState *bs, + BlockDriverState *candidate); int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename); int (*bdrv_probe_device)(const char *filename); |