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block: Don't request I/O permission with BDRV_O_NO_IO

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'qemu-img info' makes sense even when BLK_PERM_CONSISTENT_READ cannot be
granted because of a block job in a running qemu process. It already
sets BDRV_O_NO_IO to indicate that it doesn't access the guest visible
data at all.

Check the BDRV_O_NO_IO flags in blk_new_open(), so that I/O related
permissions are not unnecessarily requested and 'qemu-img info' can work
even if BLK_PERM_CONSISTENT_READ cannot be granted.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
This commit is contained in:
Kevin Wolf 2017-11-20 15:02:48 +01:00
parent dacaa16238
commit 1f4ad7d3b8
1 changed files with 6 additions and 4 deletions
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10
block/block-backend.c
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@ -299,7 +299,7 @@ BlockBackend *blk_new_open(const char *filename, const char *reference,
{
BlockBackend *blk;
BlockDriverState *bs;
uint64_t perm;
uint64_t perm = 0;
/* blk_new_open() is mainly used in .bdrv_create implementations and the
* tools where sharing isn't a concern because the BDS stays private, so we
@ -309,9 +309,11 @@ BlockBackend *blk_new_open(const char *filename, const char *reference,
* caller of blk_new_open() doesn't make use of the permissions, but they
* shouldn't hurt either. We can still share everything here because the
* guest devices will add their own blockers if they can't share. */
perm = BLK_PERM_CONSISTENT_READ;
if (flags & BDRV_O_RDWR) {
perm |= BLK_PERM_WRITE;
if ((flags & BDRV_O_NO_IO) == 0) {
perm |= BLK_PERM_CONSISTENT_READ;
if (flags & BDRV_O_RDWR) {
perm |= BLK_PERM_WRITE;
}
}
if (flags & BDRV_O_RESIZE) {
perm |= BLK_PERM_RESIZE;