v2: Lock byte 1 in the image itself, no lock file. [Daniel]
Fix migration (image are not locked in bdrv_open_common if
BDRV_O_INACTIVE). [Denis]
Simplify test case fixes because of the above.
Add lock for RBD.
Add "-L" option in "qemu-img" and "qemu-nbd" too. [Denis]
Add test case for image locking.
Too many troubles have been caused by two processes writing to the same image
unexpectedly. This series introduces automatical image locking into QEMU to
avoid such tragedy. With this, the user won't be able to open the image from
two processes (e.g. using qemu-img when the image is attached to the guest).
Underneath is the fcntl syscall that locks the local file, similar to what is
already used in libvirt virtlockd. The difference is that libvirt locks byte 0,
we lock byte 1. Read only openings are mapped to shared locks.
The alternative locking API, flock(2), cannot protect host NFS mount points, so
it's not used.
Gluster locking is also implemented wrapping glfs_posix_lock in patch 6. It's
only lightly tested.
All other drivers that don't implement .bdrv_lockf are always permissive and
does no checking.
In the future, the intention is that image format drivers that introduce
locking mechanisms could also fit into this API.
Fam Zheng (17):
block: Add BDRV_O_NO_LOCK
qapi: Add lock-image in blockdev-add options
blockdev: Add and parse "lock-image" option for block devices
block: Introduce image file locking
raw-posix: Implement .bdrv_lockf
gluster: Implement .bdrv_lockf
rbd: Implement image locking
qemu-io: Add "-L" option for BDRV_O_NO_LOCK
qemu-img: Add "-L" option to sub commands
qemu-img: Update documentation of "-L" option
qemu-nbd: Add "--no-lock/-L" option
qemu-iotests: 140: Disable image lock for qemu-io access
qemu-iotests: 046: Move version detection out from verify_io
qemu-iotests: Wait for QEMU processes before checking image in 091
qemu-iotests: Disable image lock when checking test image
block: Turn on image locking by default
qemu-iotests: Add test case 152 for image locking
block.c | 42 ++++++++
block/gluster.c | 30 ++++++
block/raw-posix.c | 35 +++++++
block/rbd.c | 25 +++++
blockdev.c | 8 ++
include/block/block.h | 1 +
include/block/block_int.h | 12 +++
qapi/block-core.json | 6 +-
qemu-img-cmds.hx | 44 ++++-----
qemu-img.c | 90 +++++++++++++----
qemu-img.texi | 3 +
qemu-io.c | 22 ++++-
qemu-nbd.c | 6 +-
qemu-nbd.texi | 2 +
tests/qemu-iotests/030 | 2 +-
tests/qemu-iotests/046 | 22 +++--
tests/qemu-iotests/091 | 3 +
tests/qemu-iotests/091.out | 1 +
tests/qemu-iotests/140 | 2 +-
tests/qemu-iotests/152 | 106 ++++++++++++++++++++
tests/qemu-iotests/152.out | 237 +++++++++++++++++++++++++++++++++++++++++++++
tests/qemu-iotests/group | 1 +
22 files changed, 645 insertions(+), 55 deletions(-)
create mode 100755 tests/qemu-iotests/152
create mode 100644 tests/qemu-iotests/152.out
--
2.8.0
