qemu-e2k/hw/block/dataplane
Kevin Wolf 86b1cf3227 block: Separate blk_is_writable() and blk_supports_write_perm()
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>
Message-Id: <20210118123448.307825-2-kwolf@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2021-01-27 20:45:20 +01:00
..
meson.build meson: convert hw/block 2020-08-21 06:30:32 -04:00
trace-events trace-events: Shorten file names in comments 2019-03-22 16:18:07 +00:00
trace.h trace: switch position of headers to what Meson requires 2020-08-21 06:18:24 -04:00
virtio-blk.c block: Honor blk_set_aio_context() context requirements 2021-01-20 14:48:08 -06:00
virtio-blk.h
xen-block.c block: Separate blk_is_writable() and blk_supports_write_perm() 2021-01-27 20:45:20 +01:00
xen-block.h xen-block: support feature-large-sector-size 2019-06-24 10:42:29 +01:00