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/block/fdc.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'hw/block/fdc.c') diff --git a/hw/block/fdc.c b/hw/block/fdc.c index 3636874..292ea87 100644 --- a/hw/block/fdc.c +++ b/hw/block/fdc.c @@ -444,7 +444,7 @@ static void fd_revalidate(FDrive *drv) FLOPPY_DPRINTF("revalidate\n"); if (drv->blk != NULL) { - drv->ro = blk_is_read_only(drv->blk); + drv->ro = !blk_is_writable(drv->blk); if (!blk_is_inserted(drv->blk)) { FLOPPY_DPRINTF("No disk in drive\n"); drv->disk = FLOPPY_DRIVE_TYPE_NONE; @@ -479,8 +479,8 @@ static void fd_change_cb(void *opaque, bool load, Error **errp) blk_set_perm(drive->blk, 0, BLK_PERM_ALL, &error_abort); } else { if (!blkconf_apply_backend_options(drive->conf, - blk_is_read_only(drive->blk), false, - errp)) { + !blk_supports_write_perm(drive->blk), + false, errp)) { return; } } @@ -553,7 +553,8 @@ static void floppy_drive_realize(DeviceState *qdev, Error **errp) * read-only node later */ read_only = true; } else { - read_only = !blk_bs(dev->conf.blk) || blk_is_read_only(dev->conf.blk); + read_only = !blk_bs(dev->conf.blk) || + !blk_supports_write_perm(dev->conf.blk); } if (!blkconf_blocksizes(&dev->conf, errp)) { -- cgit v1.1