Juan Quintela <quint...@redhat.com> wrote: > Hi Nack myself :-(
After discussions with hch on irc, he "convinced" me that only way to fix the problem is forcing O_DIRECT if migration is going to happen. So, changing patchset to check that cache=none is used in all read/write devices. Later, Juan. > This patch set creates infrastructure to invalidate buffers on > migration target machine. The best way to see the problems is: > > # create a new qcow2 image > qemu-img create -f qcow2 foo.img > # start the destination host > qemu .... path=foo.img.... > # start the source host with one installation > qemu .... path=foo.img.... > # migrate after lots of disk writes > > Destination will have "read" the beggining of the blocks of the file > (where the headers are). There are two bugs here: > a- we need to re-read the image after migration, to have the new values > (reopening fixes it) > b- we need to be sure that we read the new blocks that are on the server, > not the buffered ones locally from the start of the run. > NFS: flush on source and close + open on target invalidates the cache > Block devices: on linux, BLKFLSBUF invalidates all the buffers for that > device. This fixes iSCSI & FiberChannel. > > I tested iSCSI & NFS. NFS patch have been on RHEL5 kvm forever (I just > forget to send the patch upstream). Our NFS gurus & cluster gurus told > that this is enough for linux to ensure consistence. > > Once there, I fixed a couple of minor bugs (the first 3 patches): > - migration should exit with error 1 as everything else. > - memory leak on drive_uninit. > - fix cleanup on error on drive_init() > > Later, Juan. > > Juan Quintela (5): > migration: exit with error code > blockdev: don't leak id on removal > blockdev: release resources in the error case > Reopen files after migration > drive_open: Add invalidate option for block devices > > block.h | 2 ++ > block/raw-posix.c | 24 ++++++++++++++++++++++++ > blockdev.c | 53 > +++++++++++++++++++++++++++++++++++++++++++++-------- > blockdev.h | 6 ++++++ > migration.c | 8 +++++++- > vl.c | 2 +- > 6 files changed, 85 insertions(+), 10 deletions(-)
