Re: [Qemu-devel] block: Update flags in bdrv_set_read_only()

[Michael Tokarev]

    commit eeae6a596b0efc092f5101c67683053e245e6250
    Author: Kevin Wolf <address@hidden>
    Date:   Tue Oct 9 16:57:12 2018 +0200

        block: Update flags in bdrv_set_read_only()

        To fully change the read-only state of a node, we must not only change
        bs->read_only, but also update bs->open_flags.

sort of broke vfat support:

 $ qemu-system-x86_64 -hda fat:foo/
 WARNING: Image format was not specified for 'json:{"fat-type": 0, "dir": "foo/", "driver": 
"vvfat", "floppy": false, "rw": false}' and probing guessed raw.
          Automatically detecting the format is dangerous for raw images, write 
operations on block 0 will be restricted.
          Specify the 'raw' format explicitly to remove the restrictions.
 qemu-system-x86_64: Initialization of device ide-hd failed: Block node is 
read-only
 $ _

The warning is annoying but harmless, but the read-only error is fatal.

"Sort-of" is because there's a somewhat strange workaround:

  -hda fat:rw:foo/

but it is a bit more dangerous as well.

It looks like vfat should be handled differently somewhere, to
eliminate both the warning and the error?

Thanks,

/mjt