[Libguestfs] [PATCH nbdkit v5 FINAL 04/19] blocksize: Implement extents.
---
filters/blocksize/nbdkit-blocksize-filter.pod | 4 ++--
filters/blocksize/blocksize.c | 19 +++++++++++++++++++
2 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/filters/blocksize/nbdkit-blocksize-filter.pod
b/filters/blocksize/nbdkit-blocksize-filter.pod
index b6cf4dd..0abed2f 100644
--- a/filters/blocksize/nbdkit-blocksize-filter.pod
+++ b/filters/blocksize/nbdkit-blocksize-filter.pod
@@ -56,8 +56,8 @@ of 1024.
=item B<maxlen=>SIZE
-The maximum length for any single transaction without data (trim and
-zero). If omitted, this defaults to 0xffffffff rounded down to
+The maximum length for any single transaction without data (trim, zero
+or extents). If omitted, this defaults to 0xffffffff rounded down to
C<minsize> alignment (that is, the inherent 32-bit limit of the NBD
protocol). This need not be a power of two, but must be an integer
multiple of C<minblock>, and should be at least as large as
diff --git a/filters/blocksize/blocksize.c b/filters/blocksize/blocksize.c
index 9e0e713..55b2d59 100644
--- a/filters/blocksize/blocksize.c
+++ b/filters/blocksize/blocksize.c
@@ -45,6 +45,7 @@
#include <nbdkit-filter.h>
#include "minmax.h"
+#include "rounding.h"
/* XXX See design comment in filters/cow/cow.c. */
#define THREAD_MODEL NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS
@@ -372,6 +373,23 @@ blocksize_zero (struct nbdkit_next_ops *next_ops, void *nxdata,
return 0;
}
+static int
+blocksize_extents (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offset,
+ uint32_t flags, struct nbdkit_extents *extents, int *err)
+{
+ /* Ask the plugin for blocksize-aligned data. Since the extents
+ * list start is set to the real offset, everything before the
+ * offset is ignored automatically. Also we only need to ask for
+ * maxlen of data, because it's fine to return less than the full
+ * count as long as we're making progress.
+ */
+ return next_ops->extents (nxdata,
+ MIN (count, maxlen),
+ ROUND_DOWN (offset, minblock),
+ flags, extents, err);
+}
+
static struct nbdkit_filter filter = {
.name = "blocksize",
.longname = "nbdkit blocksize filter",
@@ -386,6 +404,7 @@ static struct nbdkit_filter filter = {
.pwrite = blocksize_pwrite,
.trim = blocksize_trim,
.zero = blocksize_zero,
+ .extents = blocksize_extents,
};
NBDKIT_REGISTER_FILTER(filter)
--
2.20.1