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[Qemu-devel] [PATCH v4 1/4] block: pass bdrv_* methods to bs->file by de
From: |
Manos Pitsidianakis |
Subject: |
[Qemu-devel] [PATCH v4 1/4] block: pass bdrv_* methods to bs->file by default in block filters |
Date: |
Tue, 11 Jul 2017 19:37:45 +0300 |
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.
Signed-off-by: Manos Pitsidianakis <address@hidden>
---
block.c | 21 +++++++++++++++++++--
include/block/block_int.h | 6 +++++-
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/block.c b/block.c
index 69439628..7f7530b6 100644
--- a/block.c
+++ b/block.c
@@ -494,6 +494,8 @@ 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;
@@ -511,6 +513,8 @@ 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;
@@ -3406,11 +3410,15 @@ int bdrv_truncate(BdrvChild *child, int64_t offset,
Error **errp)
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, errp);
+ }
error_setg(errp, "Image format driver does not support resize");
return -ENOTSUP;
}
@@ -3778,6 +3786,9 @@ 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;
@@ -3832,10 +3843,16 @@ 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 15fa6021..75e93f72 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.
--
2.11.0
- Re: [Qemu-devel] [PATCH v4 2/4] block: remove bdrv_media_changed, (continued)
Re: [Qemu-devel] [PATCH v4 2/4] block: remove bdrv_media_changed, Stefan Hajnoczi, 2017/07/12
Re: [Qemu-devel] [PATCH v4 2/4] block: remove bdrv_media_changed, Eric Blake, 2017/07/12
[Qemu-devel] [PATCH v4 3/4] block: remove bdrv_truncate callback in blkdebug, Manos Pitsidianakis, 2017/07/11
[Qemu-devel] [PATCH v4 4/4] block: add default implementations for bdrv_co_get_block_status(), Manos Pitsidianakis, 2017/07/11
[Qemu-devel] [PATCH v4 1/4] block: pass bdrv_* methods to bs->file by default in block filters,
Manos Pitsidianakis <=
Re: [Qemu-devel] [PATCH v4 0/4] block: Block driver callbacks fixes, Markus Armbruster, 2017/07/12