| Message ID | 20170922125559.11768-1-kwolf@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 09/22 14:55, Kevin Wolf wrote: > 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> > --- > qemu-io-cmds.c | 12 ++++++++++++ > tests/qemu-iotests/187.out | 2 +- > 2 files changed, 13 insertions(+), 1 deletion(-) > > 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 > -- > 2.13.5 > Reviewed-by: Fam Zheng <famz@redhat.com>
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
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> --- qemu-io-cmds.c | 12 ++++++++++++ tests/qemu-iotests/187.out | 2 +- 2 files changed, 13 insertions(+), 1 deletion(-)