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-rw-r--r--block.c65
-rw-r--r--block/blkverify.c2
-rw-r--r--blockdev.c2
-rw-r--r--include/block/block.h20
-rw-r--r--include/block/block_int.h12
5 files changed, 77 insertions, 24 deletions
diff --git a/block.c b/block.c
index 064df90917..18c0a8dd94 100644
--- a/block.c
+++ b/block.c
@@ -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);