From 86b1cf322789b79c8ace977430ac6a443d491cc0 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 18 Jan 2021 13:34:47 +0100 Subject: block: Separate blk_is_writable() and blk_supports_write_perm() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Message-Id: <20210118123448.307825-2-kwolf@redhat.com> Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Max Reitz Signed-off-by: Kevin Wolf --- hw/usb/dev-storage.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'hw/usb/dev-storage.c') diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c index f0f0058..c49e8b8 100644 --- a/hw/usb/dev-storage.c +++ b/hw/usb/dev-storage.c @@ -613,8 +613,8 @@ static void usb_msd_storage_realize(USBDevice *dev, Error **errp) return; } - if (!blkconf_apply_backend_options(&s->conf, blk_is_read_only(blk), true, - errp)) { + if (!blkconf_apply_backend_options(&s->conf, !blk_supports_write_perm(blk), + true, errp)) { return; } -- cgit v1.1