[Libguestfs] [nbdkit PATCH 10/10] plugins: Wire up nbd plugin support for NBD_INFO_INIT_STATE

The NBD protocol is adding an extension to let servers advertise initialization state to the client: whether the image contains holes, and whether it is known to read as all zeroes. With recent enough libnbd, the nbd plugin can pass this information through. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- plugins/nbd/nbd.c | 40 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 39 insertions(+), 1 deletion(-) diff --git a/plugins/nbd/nbd.c b/plugins/nbd/nbd.c index d020bee..8f06420 100644 --- a/plugins/nbd/nbd.c +++ b/plugins/nbd/nbd.c @@ -1,5 +1,5 @@ /* nbdkit - * Copyright (C) 2017-2019 Red Hat Inc. + * Copyright (C) 2017-2020 Red Hat Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are @@ -702,6 +702,42 @@ nbdplug_can_extents (void *handle) return i; } +static int +nbdplug_init_sparse (void *handle) +{ + struct handle *h = handle; + int i = 0; + +#if LIBNBD_HAVE_NBD_GET_INIT_FLAGS + i = nbd_get_init_flags (h->nbd); + + if (i == -1) { + nbdkit_error ("failure to check init flags: %s", nbd_get_error ()); + return -1; + } + i = !!(i & LIBNBD_INIT_SPARSE); +#endif + return i; +} + +static int +nbdplug_init_zero (void *handle) +{ + struct handle *h = handle; + int i = 0; + +#if LIBNBD_HAVE_NBD_GET_INIT_FLAGS + i = nbd_get_init_flags (h->nbd); + + if (i == -1) { + nbdkit_error ("failure to check init flags: %s", nbd_get_error ()); + return -1; + } + i = !!(i & LIBNBD_INIT_ZERO); +#endif + return i; +} + /* Read data from the file. */ static int nbdplug_pread (void *handle, void *buf, uint32_t count, uint64_t offset, @@ -860,6 +896,8 @@ static struct nbdkit_plugin plugin = { .can_multi_conn = nbdplug_can_multi_conn, .can_extents = nbdplug_can_extents, .can_cache = nbdplug_can_cache, + .init_sparse = nbdplug_init_sparse, + .init_zero = nbdplug_init_zero, .pread = nbdplug_pread, .pwrite = nbdplug_pwrite, .zero = nbdplug_zero, -- 2.24.1