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vvfat: Implement .bdrv_child_perm()

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vvfat is the last remaining driver that can have children, but doesn't
implement .bdrv_child_perm() yet. The default handlers aren't suitable
here, so let's implement a very simple driver-specific one that protects
the internal child from being used by other users as good as our
permissions permit.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Kevin Wolf 2016-12-20 16:23:46 +01:00
parent 862f215fab
commit 91ef38257a
3 changed files with 24 additions and 1 deletions
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2
block.c
View File

@ -823,7 +823,7 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options,
*child_flags = flags;
}
static const BdrvChildRole child_backing = {
const BdrvChildRole child_backing = {
.inherit_options = bdrv_backing_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_end = bdrv_child_cb_drained_end,

22
block/vvfat.c
View File

@ -3052,6 +3052,27 @@ err:
return ret;
}
static void vvfat_child_perm(BlockDriverState *bs, BdrvChild *c,
const BdrvChildRole *role,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
BDRVVVFATState *s = bs->opaque;
assert(c == s->qcow || role == &child_backing);
if (c == s->qcow) {
/* This is a private node, nobody should try to attach to it */
*nperm = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE;
*nshared = BLK_PERM_WRITE_UNCHANGED;
} else {
/* The backing file is there so 'commit' can use it. vvfat doesn't
* access it in any way. */
*nperm = 0;
*nshared = BLK_PERM_ALL;
}
}
static void vvfat_close(BlockDriverState *bs)
{
BDRVVVFATState *s = bs->opaque;
@ -3077,6 +3098,7 @@ static BlockDriver bdrv_vvfat = {
.bdrv_file_open = vvfat_open,
.bdrv_refresh_limits = vvfat_refresh_limits,
.bdrv_close = vvfat_close,
.bdrv_child_perm = vvfat_child_perm,
.bdrv_co_preadv = vvfat_co_preadv,
.bdrv_co_pwritev = vvfat_co_pwritev,

1
include/block/block_int.h
View File

@ -466,6 +466,7 @@ struct BdrvChildRole {
extern const BdrvChildRole child_file;
extern const BdrvChildRole child_format;
extern const BdrvChildRole child_backing;
struct BdrvChild {
BlockDriverState *bs;