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[Qemu-devel] [PATCH for-4.1 1/2] fdc: Fix inserting read-only media in e
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH for-4.1 1/2] fdc: Fix inserting read-only media in empty drive |
Date: |
Tue, 30 Jul 2019 16:57:26 +0200 |
In order to insert a read-only medium (i.e. a read-only block node) to
the BlockBackend of a floppy drive, we must not have taken write
permissions on that BlockBackend, or the operation will fail with the
error message "Block node is read-only".
The device already takes care to remove all permissions when the medium
is ejected, but the state isn't correct if the drive is initially empty:
It uses blk_is_read_only() to check whether write permissions should be
taken, but this function returns false for empty BlockBackends in the
common case.
Fix floppy_drive_realize() to avoid taking write permissions if the
drive is empty.
Signed-off-by: Kevin Wolf <address@hidden>
---
hw/block/fdc.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 77af9979de..9b24cb9b85 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -514,6 +514,7 @@ static void floppy_drive_realize(DeviceState *qdev, Error
**errp)
FloppyDrive *dev = FLOPPY_DRIVE(qdev);
FloppyBus *bus = FLOPPY_BUS(qdev->parent_bus);
FDrive *drive;
+ bool read_only;
int ret;
if (dev->unit == -1) {
@@ -542,6 +543,12 @@ static void floppy_drive_realize(DeviceState *qdev, Error
**errp)
dev->conf.blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
ret = blk_attach_dev(dev->conf.blk, qdev);
assert(ret == 0);
+
+ /* Don't take write permissions on an empty drive to allow attaching a
+ * read-only node later */
+ read_only = true;
+ } else {
+ read_only = !blk_bs(dev->conf.blk) || blk_is_read_only(dev->conf.blk);
}
blkconf_blocksizes(&dev->conf);
@@ -559,9 +566,7 @@ static void floppy_drive_realize(DeviceState *qdev, Error
**errp)
dev->conf.rerror = BLOCKDEV_ON_ERROR_AUTO;
dev->conf.werror = BLOCKDEV_ON_ERROR_AUTO;
- if (!blkconf_apply_backend_options(&dev->conf,
- blk_is_read_only(dev->conf.blk),
- false, errp)) {
+ if (!blkconf_apply_backend_options(&dev->conf, read_only, false, errp)) {
return;
}
--
2.20.1