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-sta...@nongnu.org
Signed-off-by: Kevin Wolf
---
include/sysemu/block-backend.h | 3 ++-
block/block-backend.c | 19 ---
hw/block/dataplane/xen-block.c | 2 +-
hw/block/fdc.c | 9 +
hw/block/m25p80.c | 6 +++---
hw/block/nand.c| 2 +-
hw/block/nvme-ns.c | 7 ---
hw/block/onenand.c | 2 +-
hw/block/pflash_cfi01.c| 2 +-
hw/block/pflash_cfi02.c| 2 +-
hw/block/swim.c| 6 +++---
hw/block/virtio-blk.c | 6 +++---
hw/block/xen-block.c | 2 +-
hw/ide/core.c | 2 +-
hw/misc/sifive_u_otp.c | 2 +-
hw/ppc/pnv_pnor.c | 2 +-
hw/scsi/scsi-disk.c| 10 +-
hw/scsi/scsi-generic.c | 4 ++--
hw/sd/sd.c | 6 +++---
hw/usb/dev-storage.c | 4 ++--
20 files changed, 57 insertions(+), 41 deletions(-)
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 8203d7f6f9..880e903293 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -191,7 +191,8 @@ BlockErrorAction blk_get_error_action(BlockBackend *blk,
bool is_read,
int error);
void blk_error_action(BlockBackend *blk, BlockErrorAction action,
bool is_read, int error);
-bool blk_is_read_only(BlockBackend *blk);
+bool blk_supports_write_perm(BlockBackend *blk);
+bool blk_is_writable(BlockBackend *blk);
bool blk_is_sg(BlockBackend *blk);
bool blk_enable_write_cache(BlockBackend *blk);
void blk_set_enable_write_cache(BlockBackend *blk, bool wce);
diff --git a/block/block-backend.c b/block/block-backend.c
index ce78d30794..e493f17515 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1826,17 +1826,30 @@ void blk_error_action(BlockBackend *blk,
BlockErrorAction action,
}
}
-bool blk_is_read_only(BlockBackend *blk)
+/*
+ * Returns true if the BlockBackend can support taking write permissions
+ * (because its root node is not read-only).
+ */
+bool blk_supports_write_perm(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
if (bs) {
-return bdrv_is_read_only(bs);
+return !bdrv_is_read_only(bs);
} else {
-return blk->root_state.read_only;
+return !blk->root_state.read_only;
}
}
+/*
+ * Returns true if the BlockBackend can be written to in its current
+ * configuration (i.e. if write permission have been requested)
+ */
+bool blk_is_writable(BlockBackend *blk)
+{
+return blk->perm & BLK_PERM_WRITE;
+}
+
bool blk_is_sg(BlockBackend *blk)
{
BlockDriverState *bs = blk_bs(blk);
diff --git a/hw/block/dataplane/xen-block.c b/hw/block/dataplane/xen-block.c
index 71c337c7b7..f5b4f4c079 100644
--- a/hw/block/dataplane/xen-block.c
+++ b/hw/block/dataplane/xen-block.c
@@ -168,7 +168,7 @@ static int xen_block_parse_request(XenBlockRequest *request)
};
if (request->req.operation != BLKIF_OP_READ &&
-blk_is_read_only(dataplane->blk)) {
+!blk_is_writable(dataplane->blk)) {
error_report("error: write req for ro device");
goto err;
}
diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 3636874432..292ea87805 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,
-
