diff mbox series

[PULL,12/24] qemu-io: Drop write permissions before read-only reopen

Message ID 20170926142133.2498-13-kwolf@redhat.com
State New
Headers show
Series [PULL,01/24] qemu-iotests: Add missing -machine accel=qtest | expand

Commit Message

Kevin Wolf Sept. 26, 2017, 2:21 p.m. UTC 
qemu-io provides a 'reopen' command that allows switching from writable
to read-only access. We need to make sure that we don't try to keep
write permissions to a BlockBackend that becomes read-only, otherwise
things are going to fail.

This requires a bdrv_drain() call because otherwise in-flight AIO
write requests could issue new internal requests while the permission
has already gone away, which would cause assertion failures. Draining
the queue doesn't break AIO requests in any new way, bdrv_reopen() would
drain it anyway only a few lines later.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
---
 qemu-io-cmds.c             | 12 ++++++++++++
 tests/qemu-iotests/187.out |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 2811a89099..3727fb43f3 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -2010,6 +2010,18 @@  static int reopen_f(BlockBackend *blk, int argc, char **argv)
         return 0;
     }
 
+    if (!(flags & BDRV_O_RDWR)) {
+        uint64_t orig_perm, orig_shared_perm;
+
+        bdrv_drain(bs);
+
+        blk_get_perm(blk, &orig_perm, &orig_shared_perm);
+        blk_set_perm(blk,
+                     orig_perm & ~(BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED),
+                     orig_shared_perm,
+                     &error_abort);
+    }
+
     qopts = qemu_opts_find(&reopen_opts, NULL);
     opts = qopts ? qemu_opts_to_qdict(qopts, NULL) : NULL;
     qemu_opts_reset(&reopen_opts);
diff --git a/tests/qemu-iotests/187.out b/tests/qemu-iotests/187.out
index 68fb944cd5..30b987f71f 100644
--- a/tests/qemu-iotests/187.out
+++ b/tests/qemu-iotests/187.out
@@ -12,7 +12,7 @@  Start from read-write
 
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-write failed: Operation not permitted
+Block node is read-only
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 *** done