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authorManos Pitsidianakis <el13635@mail.ntua.gr>2017-07-13 18:30:25 +0300
committerKevin Wolf <kwolf@redhat.com>2017-09-04 18:31:13 +0200
commit5a612c009ee538a3b32c896f9a6c5562a50efe9d (patch)
tree9e33b62dd41f222d3712d2adf3ce21145787520e
parent98bfaac788be0ca63d7d010c8d4ba100ff1d8278 (diff)
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block: pass bdrv_* methods to bs->file by default in block filters
The following functions fail if bs->drv is a filter and does not implement them: bdrv_probe_blocksizes bdrv_probe_geometry bdrv_truncate bdrv_has_zero_init bdrv_get_info Instead, the call should be passed to bs->file if it exists, to allow filter drivers to support those methods without implementing them. This commit makes `drv->is_filter = true` imply that these callbacks will be forwarded to bs->file by default, so disabling support for these functions must be done explicitly. Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--block.c21
-rw-r--r--include/block/block_int.h6
2 files changed, 24 insertions, 3 deletions
diff --git a/block.c b/block.c
index b749bd6..175e8d3 100644
--- a/block.c
+++ b/block.c
@@ -496,6 +496,8 @@ int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
if (drv && drv->bdrv_probe_blocksizes) {
return drv->bdrv_probe_blocksizes(bs, bsz);
+ } else if (drv && drv->is_filter && bs->file) {
+ return bdrv_probe_blocksizes(bs->file->bs, bsz);
}
return -ENOTSUP;
@@ -513,6 +515,8 @@ int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
if (drv && drv->bdrv_probe_geometry) {
return drv->bdrv_probe_geometry(bs, geo);
+ } else if (drv && drv->is_filter && bs->file) {
+ return bdrv_probe_geometry(bs->file->bs, geo);
}
return -ENOTSUP;
@@ -3426,11 +3430,15 @@ int bdrv_truncate(BdrvChild *child, int64_t offset, PreallocMode prealloc,
assert(child->perm & BLK_PERM_RESIZE);
+ /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
if (!drv) {
error_setg(errp, "No medium inserted");
return -ENOMEDIUM;
}
if (!drv->bdrv_truncate) {
+ if (bs->file && drv->is_filter) {
+ return bdrv_truncate(bs->file, offset, prealloc, errp);
+ }
error_setg(errp, "Image format driver does not support resize");
return -ENOTSUP;
}
@@ -3767,6 +3775,9 @@ int bdrv_has_zero_init(BlockDriverState *bs)
if (bs->drv->bdrv_has_zero_init) {
return bs->drv->bdrv_has_zero_init(bs);
}
+ if (bs->file && bs->drv->is_filter) {
+ return bdrv_has_zero_init(bs->file->bs);
+ }
/* safe default */
return 0;
@@ -3821,10 +3832,16 @@ void bdrv_get_backing_filename(BlockDriverState *bs,
int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
BlockDriver *drv = bs->drv;
- if (!drv)
+ /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
+ if (!drv) {
return -ENOMEDIUM;
- if (!drv->bdrv_get_info)
+ }
+ if (!drv->bdrv_get_info) {
+ if (bs->file && drv->is_filter) {
+ return bdrv_get_info(bs->file->bs, bdi);
+ }
return -ENOTSUP;
+ }
memset(bdi, 0, sizeof(*bdi));
return drv->bdrv_get_info(bs, bdi);
}
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 7571c0a..71183cc 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -87,7 +87,11 @@ struct BlockDriver {
const char *format_name;
int instance_size;
- /* set to true if the BlockDriver is a block filter */
+ /* set to true if the BlockDriver is a block filter. Block filters pass
+ * certain callbacks that refer to data (see block.c) to their bs->file if
+ * the driver doesn't implement them. Drivers that do not wish to forward
+ * must implement them and return -ENOTSUP.
+ */
bool is_filter;
/* for snapshots block filter like Quorum can implement the
* following recursive callback.