Re: [libvirt] [PATCH v2 4/7] lockd_driver_lockd: Implement metadata flag

On 08/17/2018 01:53 AM, John Ferlan wrote: > > > On 08/14/2018 07:19 AM, Michal Privoznik wrote: >> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; >> --- >> src/locking/lock_daemon_dispatch.c | 12 ++++++++++-- >> src/locking/lock_driver_lockd.c | 31 +++++++++++++++++++++---------- >> src/locking/lock_driver_lockd.h | 1 + >> 3 files changed, 32 insertions(+), 12 deletions(-) >> >> diff --git a/src/locking/lock_daemon_dispatch.c b/src/locking/lock_daemon_dispatch.c >> index 10248ec0b5..c24571ceac 100644 >> --- a/src/locking/lock_daemon_dispatch.c >> +++ b/src/locking/lock_daemon_dispatch.c >> @@ -37,6 +37,9 @@ VIR_LOG_INIT("locking.lock_daemon_dispatch"); >> >> #include "lock_daemon_dispatch_stubs.h" >> >> +#define DEFAULT_OFFSET 0 >> +#define METADATA_OFFSET 1 >> + > > Curious, does this lead to the prospect of being able to acquire/use > offset==0 length==1 and offset==1 length==1 at least conceptually and > granularity wise? Yes, this is exactly the purpose. I've taken inspiration from qemu. They lock bytes from 100 to 100 + N, depending on what operations they want the disk for (checkout raw_apply_lock_bytes() form block/file-posix.c). And my idea was for virtlockd to do the same. Currently, it locks 0th byte of given file and with metadata flag it would lock the first one.