Currently, blk_is_read_only() tells whether a given BlockBackend can
only be used in read-only mode because its root node is read-only. Some
callers actually try to answer a slightly different question: Is the
BlockBackend configured to be writable, by taking write permissions on
the root node?
This can differ, for example, for CD-ROM devices which don't take write
permissions, but may be backed by a writable image file. scsi-cd allows
write requests to the drive if blk_is_read_only() returns false.
However, the write request will immediately run into an assertion
failure because the write permission is missing.
This patch introduces separate functions for both questions.
blk_supports_write_perm() answers the question whether the block
node/image file can support writable devices, whereas blk_is_writable()
tells whether the BlockBackend is currently configured to be writable.
All calls of blk_is_read_only() are converted to one of the two new
functions.
Fixes: https://bugs.launchpad.net/bugs/1906693
Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/sysemu/block-backend.h | 3 ++-
block/block-backend.c | 19 ++++++++++++++++---
hw/block/dataplane/xen-block.c | 2 +-
hw/block/fdc.c | 9 +++++----
hw/block/m25p80.c | 6 +++---
hw/block/nand.c | 2 +-
hw/block/nvme-ns.c | 7 ++++---
hw/block/onenand.c | 2 +-
hw/block/pflash_cfi01.c | 2 +-
hw/block/pflash_cfi02.c | 2 +-
hw/block/swim.c | 6 +++---
hw/block/virtio-blk.c | 6 +++---
hw/block/xen-block.c | 2 +-
hw/ide/core.c | 2 +-
hw/misc/sifive_u_otp.c | 2 +-
hw/ppc/pnv_pnor.c | 2 +-
hw/scsi/scsi-disk.c | 10 +++++-----
hw/scsi/scsi-generic.c | 4 ++--
hw/sd/sd.c | 6 +++---
hw/usb/dev-storage.c | 4 ++--
20 files changed, 57 insertions(+), 41 deletions(-)