[Libguestfs] [PATCH nbdkit 1/9] server: Implement extents/can_extents calls for plugins and filters.
Richard W.M. Jones
rjones at redhat.com
Tue Mar 19 16:34:58 UTC 2019
This pair of calls allows plugins to describe which extents in the
virtual disk are allocated, holes or zeroes.
---
docs/nbdkit-filter.pod | 107 ++++++++
docs/nbdkit-plugin.pod | 103 +++++++
include/nbdkit-common.h | 10 +-
include/nbdkit-filter.h | 25 +-
include/nbdkit-plugin.h | 6 +-
server/internal.h | 5 +
server/extents.c | 574 ++++++++++++++++++++++++++++++++++++++++
server/filters.c | 61 +++++
server/plugins.c | 56 +++-
server/test-extents.c | 151 +++++++++++
.gitignore | 1 +
server/Makefile.am | 18 +-
12 files changed, 1111 insertions(+), 6 deletions(-)
diff --git a/docs/nbdkit-filter.pod b/docs/nbdkit-filter.pod
index dc9a262..7b25c8e 100644
--- a/docs/nbdkit-filter.pod
+++ b/docs/nbdkit-filter.pod
@@ -350,6 +350,8 @@ calls.
=head2 C<.can_zero>
+=head2 C<.can_extents>
+
=head2 C<.can_fua>
=head2 C<.can_multi_conn>
@@ -365,6 +367,8 @@ calls.
void *handle);
int (*can_zero) (struct nbdkit_next_ops *next_ops, void *nxdata,
void *handle);
+ int (*can_extents) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
int (*can_fua) (struct nbdkit_next_ops *next_ops, void *nxdata,
void *handle);
int (*can_multi_conn) (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -513,6 +517,109 @@ value to return to the client. The filter should never fail with
C<EOPNOTSUPP> (while plugins have automatic fallback to C<.pwrite>,
filters do not).
+=head2 C<.extents>
+
+ int (*extents) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offset, uint32_t flags,
+ struct nbdkit_extents_map *extents_map,
+ int *err);
+
+This intercepts the plugin C<.extents> method and can be used to
+modify extent requests.
+
+This function will not be called if C<.can_extents> returned false; in
+turn, the filter should not call C<next_ops-E<gt>extents> if
+C<next_ops-E<gt>can_extents> did not return true.
+
+The C<extents_map> parameter passed to this function is empty
+(representing a fully allocated disk). If the filter does not need to
+adjust extents from the underlying plugin it can simply pass this
+through to the layer below:
+
+ myfilter_extents (...)
+ {
+ return next_ops->extents (nxdata, count, offset, flags,
+ extents_map, err);
+ }
+
+It is also possible for filters to transform the extents map received
+back from the layer below. Usually this must be done by allocating a
+new, empty map which is passed to the layer below. Without error
+handling it would look like this:
+
+ myfilter_extents (...)
+ {
+ struct nbdkit_extents_map *map2 = nbdkit_extents_new ();
+ next_ops->extents (nxdata, count, offset, flags, map2, err);
+ /* transform map2 and return results in extents_map */
+ nbdkit_extents_foreach (map2, transform_offset, extents_map, /*..*/);
+ nbdkit_extents_free (map2);
+ }
+
+If there is an error, C<.extents> should call C<nbdkit_error> with an
+error message B<and> return -1 with C<err> set to the positive errno
+value to return to the client.
+
+=head3 Allocating and freeing nbdkit_extents_map
+
+Two functions are provided to filters only for allocating and freeing
+the map:
+
+ struct nbdkit_extents_map *nbdkit_extents_new ();
+
+Allocates and returns a new, empty extents map. The initial state is
+that the whole disk is allocated with data.
+
+On error this function can return C<NULL>. In this case it calls
+C<nbdkit_error> and/or C<nbdkit_set_error> as required.
+
+ void nbdkit_extents_free (struct nbdkit_extents_map *);
+
+Frees an existing extents map.
+
+=head3 Iterating over nbdkit_extents_map
+
+One function is provided to filters only to iterate over the extents
+map:
+
+ typedef int (*nbdkit_extents_callback) (uint64_t offset, uint64_t length,
+ uint32_t type, void *opaque);
+
+ int nbdkit_extents_foreach (
+ const struct nbdkit_extents_map *extents_map,
+ nbdkit_extents_callback fn, void *opaque,
+ uint32_t flags,
+ uint64_t range_offset, uint64_t range_length);
+
+Iterate over the extents in ascending order, calling C<fn> for each.
+C<fn> should return 0 on success or -1 on failure. If a call to C<fn>
+fails then C<nbdkit_extents_foreach> also fails immediately.
+
+C<nbdkit_extents_foreach> returns C<0> on success or C<-1> on failure.
+On internal failures it calls C<nbdkit_error> or C<nbdkit_set_error>.
+If C<fn> fails it is expected that C<fn> calls those functions as
+necessary.
+
+The C<flags> parameter can contain:
+
+=over 4
+
+=item C<NBDKIT_EXTENTS_FOREACH_FLAG_ONE>
+
+Only call C<fn> for the first extent, and then return. (This is used
+to implement C<NBD_CMD_FLAG_REQ_ONE> in the NBD protocol.)
+
+=item C<NBDKIT_EXTENTS_FOREACH_FLAG_RANGE>
+
+If this flag is included then the C<range_offset> and C<range_length>
+parameters are used, so only extents overlapping
+C<[range_offset...range_offset+range_length-1]> are returned.
+
+If this flag is not included in C<flags> then the range parameters are
+I<ignored>.
+
+=back
+
=head1 ERROR HANDLING
If there is an error in the filter itself, the filter should call
diff --git a/docs/nbdkit-plugin.pod b/docs/nbdkit-plugin.pod
index 47545f3..7b7b38b 100644
--- a/docs/nbdkit-plugin.pod
+++ b/docs/nbdkit-plugin.pod
@@ -555,6 +555,20 @@ This callback is not required. If omitted, then nbdkit always tries
C<.zero> first if it is present, and gracefully falls back to
C<.pwrite> if C<.zero> was absent or failed with C<EOPNOTSUPP>.
+=head2 C<.can_extents>
+
+ int can_extents (void *handle);
+
+This is called during the option negotiation phase to find out if the
+plugin supports detecting allocated (non-sparse) regions of the disk
+with the C<.extents> callback.
+
+If there is an error, C<.can_extents> should call C<nbdkit_error> with
+an error message and return C<-1>.
+
+This callback is not required. If omitted, then we return true iff a
+C<.extents> callback has been defined.
+
=head2 C<.can_fua>
int can_fua (void *handle);
@@ -717,6 +731,95 @@ If there is an error, C<.zero> should call C<nbdkit_error> with an
error message, and C<nbdkit_set_error> to record an appropriate error
(unless C<errno> is sufficient), then return C<-1>.
+=head2 C<.extents>
+
+ int extents (void *handle, uint32_t count, uint64_t offset,
+ uint32_t flags,
+ struct nbdkit_extents_map *extents_map);
+
+During the data serving phase, this callback is used to detect
+allocated, sparse and zeroed regions of the disk.
+
+This function will not be called if C<.can_extents> returned false.
+nbdkit's default behaviour in this case is to treat the whole virtual
+disk as if it was allocated.
+
+The callback should detect and return the list of extents overlapping
+the range C<[offset...offset+count-1]>. The C<extents_map> parameter
+points to an opaque object which the callback should fill in by
+calling C<nbdkit_extent_add> etc. See L</Extents map> below.
+
+The C<flags> parameter may contain the flag C<NBDKIT_FLAG_REQ_ONE>
+which means that the client is only requesting information about the
+extent overlapping C<offset>. The plugin may ignore this flag, or as
+an optimization it may return just a single extent for C<offset>.
+(Note that implementing this optimization correctly is difficult and
+subtle. You must ensure that the upper limit of the single extent
+returned is correct. If unsure then the safest option is to ignore
+this flag.)
+
+If there is an error, C<.extents> should call C<nbdkit_error> with an
+error message, and C<nbdkit_set_error> to record an appropriate error
+(unless C<errno> is sufficient), then return C<-1>.
+
+=head3 Extents map
+
+The plugin C<extents> callback is passed an opaque pointer C<struct
+nbdkit_extents_map *extents_map>. This structure represents a list of
+L<filesystem extents|https://en.wikipedia.org/wiki/Extent_(file_systems)>
+describing which areas of the disk are allocated, which are sparse
+(“holes”), and, if supported, which are zeroes. Initially the map
+describes a single allocated data extent covering the entire virtual
+disk.
+
+The C<extents> callback has to fill in any holes or zeroes areas by
+calling C<nbdkit_extent*> functions, to describe all extents
+overlapping the range C<[offset...offset+count-1]>. (nbdkit will
+ignore extents outside this range so plugins may, if it is easier to
+implement, return all extent information for the whole disk.)
+
+The following functions are available for plugins or filters to call:
+
+ int nbdkit_extent_add (struct nbdkit_extents_map *extents_map,
+ uint64_t offset, uint64_t length, uint32_t type);
+
+Add an extent covering C<[offset...offset+length-1]> of one of
+the following four types:
+
+=over 4
+
+=item C<type = 0>
+
+A normal, allocated data extent.
+
+=item C<type = NBDKIT_EXTENT_HOLE|NBDKIT_EXTENT_ZERO>
+
+An unallocated extent, a.k.a. a “hole”, which reads back as zeroes.
+This is the normal type of hole applicable to most disks.
+
+=item C<type = NBDKIT_EXTENT_ZERO>
+
+An allocated extent which is known to contain only zeroes.
+
+=item C<type = NBDKIT_EXTENT_HOLE>
+
+An unallocated extent (hole) which does not read back as zeroes. Note
+this should only be used in specialized circumstances such as when
+writing a plugin for (or to emulate) certain SCSI drives which do not
+guarantee that trimmed blocks read back as zeroes.
+
+=back
+
+If the new extent overlaps some previous extent in the map then the
+overlapping part(s) are overwritten with the new type. Adjacent
+extents of the same type may also be coalesced. Thus you shouldn't
+assume that C<nbdkit_extent_add> always adds exactly one more extent
+to the map.
+
+C<nbdkit_extent_add> returns C<0> on success or C<-1> on failure. On
+failure C<nbdkit_error> and/or C<nbdkit_set_error> has already been
+called.
+
=head1 THREADS
Each nbdkit plugin must declare its thread safety model by defining
diff --git a/include/nbdkit-common.h b/include/nbdkit-common.h
index cb9954e..8526171 100644
--- a/include/nbdkit-common.h
+++ b/include/nbdkit-common.h
@@ -1,5 +1,5 @@
/* nbdkit
- * Copyright (C) 2013-2018 Red Hat Inc.
+ * Copyright (C) 2013-2019 Red Hat Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -60,11 +60,15 @@ extern "C" {
#define NBDKIT_FLAG_MAY_TRIM (1<<0) /* Maps to !NBD_CMD_FLAG_NO_HOLE */
#define NBDKIT_FLAG_FUA (1<<1) /* Maps to NBD_CMD_FLAG_FUA */
+#define NBDKIT_FLAG_REQ_ONE (1<<2) /* Maps to NBD_CMD_FLAG_REQ_ONE */
#define NBDKIT_FUA_NONE 0
#define NBDKIT_FUA_EMULATE 1
#define NBDKIT_FUA_NATIVE 2
+#define NBDKIT_EXTENT_HOLE (1<<0) /* Same as NBD_STATE_HOLE */
+#define NBDKIT_EXTENT_ZERO (1<<1) /* Same as NBD_STATE_ZERO */
+
extern void nbdkit_error (const char *msg, ...) ATTRIBUTE_FORMAT_PRINTF (1, 2);
extern void nbdkit_verror (const char *msg, va_list args);
extern void nbdkit_debug (const char *msg, ...) ATTRIBUTE_FORMAT_PRINTF (1, 2);
@@ -76,6 +80,10 @@ extern int nbdkit_parse_bool (const char *str);
extern int nbdkit_read_password (const char *value, char **password);
extern char *nbdkit_realpath (const char *path);
+struct nbdkit_extents_map;
+extern int nbdkit_extent_add (struct nbdkit_extents_map *,
+ uint64_t offset, uint64_t length, uint32_t type);
+
/* A static non-NULL pointer which can be used when you don't need a
* per-connection handle.
*/
diff --git a/include/nbdkit-filter.h b/include/nbdkit-filter.h
index 71c06c8..4efb98e 100644
--- a/include/nbdkit-filter.h
+++ b/include/nbdkit-filter.h
@@ -1,5 +1,5 @@
/* nbdkit
- * Copyright (C) 2013-2018 Red Hat Inc.
+ * Copyright (C) 2013-2019 Red Hat Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -44,6 +44,19 @@ extern "C" {
#define NBDKIT_FILTER_API_VERSION 2
+#define NBDKIT_EXTENTS_FOREACH_FLAG_ONE 1
+#define NBDKIT_EXTENTS_FOREACH_FLAG_RANGE 2
+
+extern struct nbdkit_extents_map *nbdkit_extents_new (void);
+extern void nbdkit_extents_free (struct nbdkit_extents_map *);
+typedef int (*nbdkit_extents_callback) (uint64_t offset, uint64_t length,
+ uint32_t type, void *opaque);
+extern int nbdkit_extents_foreach (const struct nbdkit_extents_map *,
+ nbdkit_extents_callback fn, void *opaque,
+ uint32_t flags,
+ uint64_t range_offset,
+ uint64_t range_length);
+
typedef int nbdkit_next_config (void *nxdata,
const char *key, const char *value);
typedef int nbdkit_next_config_complete (void *nxdata);
@@ -58,6 +71,7 @@ struct nbdkit_next_ops {
int (*is_rotational) (void *nxdata);
int (*can_trim) (void *nxdata);
int (*can_zero) (void *nxdata);
+ int (*can_extents) (void *nxdata);
int (*can_fua) (void *nxdata);
int (*can_multi_conn) (void *nxdata);
@@ -71,6 +85,9 @@ struct nbdkit_next_ops {
int *err);
int (*zero) (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags,
int *err);
+ int (*extents) (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags,
+ struct nbdkit_extents_map *extents_map,
+ int *err);
};
struct nbdkit_filter {
@@ -120,6 +137,8 @@ struct nbdkit_filter {
void *handle);
int (*can_zero) (struct nbdkit_next_ops *next_ops, void *nxdata,
void *handle);
+ int (*can_extents) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
int (*can_fua) (struct nbdkit_next_ops *next_ops, void *nxdata,
void *handle);
int (*can_multi_conn) (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -140,6 +159,10 @@ struct nbdkit_filter {
int (*zero) (struct nbdkit_next_ops *next_ops, void *nxdata,
void *handle, uint32_t count, uint64_t offset, uint32_t flags,
int *err);
+ int (*extents) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offset, uint32_t flags,
+ struct nbdkit_extents_map *extents_map,
+ int *err);
};
#define NBDKIT_REGISTER_FILTER(filter) \
diff --git a/include/nbdkit-plugin.h b/include/nbdkit-plugin.h
index d43b2f5..76cec54 100644
--- a/include/nbdkit-plugin.h
+++ b/include/nbdkit-plugin.h
@@ -1,5 +1,5 @@
/* nbdkit
- * Copyright (C) 2013-2018 Red Hat Inc.
+ * Copyright (C) 2013-2019 Red Hat Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -125,6 +125,10 @@ struct nbdkit_plugin {
const char *magic_config_key;
int (*can_multi_conn) (void *handle);
+
+ int (*can_extents) (void *handle);
+ int (*extents) (void *handle, uint32_t count, uint64_t offset, uint32_t flags,
+ struct nbdkit_extents_map *extents_map);
};
extern void nbdkit_set_error (int err);
diff --git a/server/internal.h b/server/internal.h
index d40a82d..d0da213 100644
--- a/server/internal.h
+++ b/server/internal.h
@@ -274,6 +274,7 @@ struct backend {
int (*is_rotational) (struct backend *, struct connection *conn);
int (*can_trim) (struct backend *, struct connection *conn);
int (*can_zero) (struct backend *, struct connection *conn);
+ int (*can_extents) (struct backend *, struct connection *conn);
int (*can_fua) (struct backend *, struct connection *conn);
int (*can_multi_conn) (struct backend *, struct connection *conn);
@@ -287,6 +288,10 @@ struct backend {
uint64_t offset, uint32_t flags, int *err);
int (*zero) (struct backend *, struct connection *conn, uint32_t count,
uint64_t offset, uint32_t flags, int *err);
+ int (*extents) (struct backend *, struct connection *conn, uint32_t count,
+ uint64_t offset, uint32_t flags,
+ struct nbdkit_extents_map *extents_map,
+ int *err);
};
/* plugins.c */
diff --git a/server/extents.c b/server/extents.c
new file mode 100644
index 0000000..f17ba05
--- /dev/null
+++ b/server/extents.c
@@ -0,0 +1,574 @@
+/* nbdkit
+ * Copyright (C) 2019 Red Hat Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include <inttypes.h>
+#include <assert.h>
+
+#include "minmax.h"
+
+#include "internal.h"
+
+/* Trivial implementation as an ordered list of extents. We will
+ * probably have to change this to a more efficient data structure if
+ * we have plugins with lots of extents.
+ *
+ * Invariants:
+ * - extents are stored in ascending order
+ * - extents must not overlap
+ * - adjacent extents must not have the same type
+ *
+ * Gaps are treated as type 0 (allocated data).
+ */
+struct nbdkit_extents_map {
+ struct extent *extents;
+ size_t nr_extents, allocated;
+};
+
+struct extent {
+ uint64_t offset;
+ uint64_t length;
+ uint32_t type;
+};
+
+struct nbdkit_extents_map *
+nbdkit_extents_new (void)
+{
+ struct nbdkit_extents_map *r;
+
+ r = malloc (sizeof *r);
+ if (r == NULL) {
+ nbdkit_error ("nbdkit_extents_new: malloc: %m");
+ return NULL;
+ }
+ r->extents = NULL;
+ r->nr_extents = r->allocated = 0;
+ return r;
+}
+
+void
+nbdkit_extents_free (struct nbdkit_extents_map *map)
+{
+ if (map) {
+ free (map->extents);
+ free (map);
+ }
+}
+
+static ssize_t
+find_extent_recursive (const struct nbdkit_extents_map *map,
+ uint64_t offset, size_t first, size_t last)
+{
+ size_t i, h;
+
+ assert (first <= last);
+ assert (offset >= map->extents[first].offset);
+
+ if (last - first <= 8) {
+ /* Do a linear search for the last bit. */
+ for (i = first+1; i <= last; ++i) {
+ if (offset < map->extents[i].offset)
+ return i-1;
+ }
+ return last;
+ }
+
+ h = first + (last - first) / 2;
+
+ if (offset < map->extents[h].offset)
+ return find_extent_recursive (map, offset, first, h-1);
+ else
+ return find_extent_recursive (map, offset, h, last);
+}
+
+/* Find the extent before or containing offset. If offset is inside
+ * the extent, the extent index is returned. If offset is not in any
+ * extent, but there is an extent with a lower offset, then the index
+ * of the nearest lower extent is returned. If offset is before the
+ * zeroth extent then -1 is returned.
+ */
+static ssize_t
+find_extent (const struct nbdkit_extents_map *map, uint64_t offset)
+{
+ if (map->nr_extents == 0 || offset < map->extents[0].offset)
+ return -1;
+
+ return find_extent_recursive (map, offset, 0, map->nr_extents-1);
+}
+
+/* Erase extents [i...i+count-1] from the array. Extents after are
+ * renumbered.
+ */
+static void
+erase_extents (struct nbdkit_extents_map *map,
+ size_t i, size_t count)
+{
+ assert (i+count <= map->nr_extents);
+
+ memmove (&map->extents[i],
+ &map->extents[i+count],
+ (map->nr_extents - (i+count)) * sizeof (struct extent));
+ map->nr_extents -= count;
+}
+
+/* Insert new_extent in the map at index i. Existing extents at index
+ * [i...] are moved up by one.
+ */
+static int
+insert_extent (struct nbdkit_extents_map *map,
+ struct extent new_extent, size_t i)
+{
+ assert (i <= map->nr_extents);
+
+ if (map->nr_extents >= map->allocated) {
+ size_t new_allocated;
+ struct extent *new_extents;
+
+ new_allocated = map->allocated;
+ if (new_allocated == 0)
+ new_allocated = 1;
+ new_allocated *= 2;
+ new_extents =
+ realloc (map->extents, new_allocated * sizeof (struct extent));
+ if (new_extents == NULL) {
+ nbdkit_error ("extent_add: realloc: %m");
+ return -1;
+ }
+ map->allocated = new_allocated;
+ map->extents = new_extents;
+ }
+
+ memmove (&map->extents[i+1], &map->extents[i],
+ (map->nr_extents - i) * sizeof (struct extent));
+ map->nr_extents++;
+ map->extents[i] = new_extent;
+ return 0;
+}
+
+int
+nbdkit_extent_add (struct nbdkit_extents_map *map,
+ uint64_t offset, uint64_t length, uint32_t type)
+{
+ ssize_t lo, hi;
+ bool coalesce_below, coalesce_above;
+ struct extent new_extent;
+
+ /* This might be considered an error, but be flexible for badly
+ * written plugins.
+ */
+ if (length == 0)
+ return 0;
+
+ /* Don't allow extents to exceeed the _signed_ 64 bit limit that is
+ * used in the rest of nbdkit.
+ */
+ if (offset > INT64_MAX ||
+ offset + length < offset ||
+ offset + length > INT64_MAX) {
+ nbdkit_error ("nbdkit_extent_add: "
+ "extent cannot exceed signed 64 bit limit: "
+ "offset=%" PRIu64 " length=%" PRIu64,
+ offset, length);
+ return -1;
+ }
+
+ again:
+ lo = find_extent (map, offset);
+ hi = find_extent (map, offset + length - 1);
+
+ /* "lo" and "hi" are -1 or they point to the extent
+ * overlapping-or-below the corresponding endpoints of the new
+ * extent.
+ *
+ * The algorithm here has two parts: Firstly we remove any
+ * overlapping extents (this may involve erasing extents completely
+ * or shrinking them). Secondly we insert the new extent at the
+ * right place in the array, if necessary allowing it to coalesce
+ * with the extent above or below.
+ *
+ * To remove overlapping extents we consider 7 cases:
+ *
+ * A.0 lo == -1 (there is no old extent before the new extent)
+ * => do nothing
+ *
+ * A.1 ┌─────┐ offset of new extent exactly at
+ * │ lo │ beginning of lo and lo smaller/equal
+ * └─────┘ to new extent
+ * ↑
+ * ▐▓▓▓▓▓▓▓▓▓
+ * => erase lo
+ * => creates situation A.0 or A.5
+ *
+ * A.2 ┌──────────┐ offset of new extent exactly at
+ * │ lo │ beginning of lo and lo bigger than
+ * └──────────┘ new extent
+ * ↑
+ * ▐▓▓▓▓▓▓▓▓▓
+ * => shrink lo “upwards”
+ * => creates situation A.0 or A.5
+ *
+ * A.3 ┌──────────────┐ new extent in the middle
+ * │ lo │ of lo
+ * └──────────────┘
+ * ↑
+ * ▓▓▓▓▓▓▓▓▓
+ * => split lo
+ * => creates situation A.5
+ *
+ * A.4 ┌─────┐ offset of new extent in the middle
+ * │ lo │ of lo
+ * └─────┘
+ * ↑
+ * ▓▓▓▓▓▓▓▓▓
+ * => shrink lo
+ * => creates situation A.5
+ *
+ * A.5 ┌─────┐ offset of new extent after lo
+ * │ lo │
+ * └─────┘
+ * ↑
+ * ▓▓▓▓▓▓▓▓▓
+ * => do nothing
+ *
+ * B.0 lo == hi or hi == -1 (there is no higher extent)
+ * => do nothing
+ *
+ * B.1 ┌─────┐ extent hi is fully covered
+ * │ hi │ by new extent
+ * └─────┘
+ * ↑
+ * ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
+ * => erase hi
+ * => creates situation B.0
+ *
+ * B.2 ┌─────┐ extent hi is partly overlapped
+ * │ hi │ by new extent
+ * └─────┘
+ * ↑
+ * ▓▓▓▓▓▓▓▓▓▓▓
+ * => shrink hi
+ * => creates situation B.0
+ *
+ * In addition extents [lo+1...hi-1] (if they exist) are erased
+ * since they must be fully covered by the new extent.
+ *
+ * At the end we're in situation A.0/A.5 and B.0, and so no old
+ * extents overlap the new extent.
+ *
+ * The insertion can then be done with optional coalescing (see code
+ * below for details - this is a lot simpler).
+ */
+
+ /* A.0 */
+ if (lo == -1)
+ goto erase_middle_extents;
+ /* A.5 */
+ if (offset >= map->extents[lo].offset + map->extents[lo].length)
+ goto erase_middle_extents;
+
+ /* A.1 or A.2 */
+ if (offset == map->extents[lo].offset) {
+ if (map->extents[lo].offset + map->extents[lo].length <= offset + length) {
+ /* A.1 */
+ erase_extents (map, lo, 1);
+ }
+ else {
+ /* A.2 */
+ uint64_t end = map->extents[lo].offset + map->extents[lo].length;
+ map->extents[lo].offset = offset + length;
+ map->extents[lo].length = end - map->extents[lo].offset;
+ }
+ goto again;
+ }
+
+ /* A.3 */
+ if (map->extents[lo].offset < offset &&
+ map->extents[lo].offset + map->extents[lo].length > offset + length) {
+ new_extent.offset = offset + length;
+ new_extent.length =
+ map->extents[lo].offset + map->extents[lo].length - new_extent.offset;
+ new_extent.type = map->extents[lo].type;
+ map->extents[lo].length = offset - map->extents[lo].offset;
+ if (insert_extent (map, new_extent, lo+1) == -1)
+ return -1;
+ goto again;
+ }
+
+ /* We must be in situation A.4 assuming analysis above is exhaustive. */
+ assert (offset > map->extents[lo].offset);
+ assert (offset < map->extents[lo].offset + map->extents[lo].length);
+ assert (map->extents[lo].offset + map->extents[lo].length <= offset + length);
+
+ map->extents[lo].length = offset - map->extents[lo].offset;
+
+ erase_middle_extents:
+ /* Erase extents [lo+1..hi-1] if they exist as they must be
+ * completely covered by the new extent.
+ */
+ if (hi >= 0 && lo+1 < hi) {
+ erase_extents (map, lo+1, hi-lo-1);
+ goto again;
+ }
+
+ /* B.0 */
+ if (lo == hi || hi == -1)
+ goto insert;
+
+ /* B.1 */
+ if (map->extents[hi].offset + map->extents[hi].length <= offset + length) {
+ erase_extents (map, hi, 1);
+ goto again;
+ }
+
+ /* We must be in situation B.2 if the analysis above is exhaustive. */
+ assert (map->extents[hi].offset < offset + length);
+
+ uint64_t end = map->extents[hi].offset + map->extents[hi].length;
+ map->extents[hi].offset = offset + length;
+ map->extents[hi].length = end - map->extents[hi].offset;
+
+ insert:
+ /* Now we know there is no extent which overlaps with the new
+ * extent, and the new extent must be inserted after lo.
+ */
+
+ /* However we have to deal with possibly coalescing the new extent
+ * with lo and/or lo+1.
+ */
+ coalesce_below =
+ lo >= 0 &&
+ map->extents[lo].type == type &&
+ map->extents[lo].offset + map->extents[lo].length == offset;
+ coalesce_above =
+ lo+1 < map->nr_extents &&
+ map->extents[lo+1].type == type &&
+ map->extents[lo+1].offset == offset + length;
+
+ if (coalesce_below && coalesce_above) {
+ /* Coalesce lo + new extent + lo+1
+ * => Extend lo to cover the whole range and remove lo+1.
+ */
+ map->extents[lo].length =
+ map->extents[lo+1].offset + map->extents[lo+1].length
+ - map->extents[lo].offset;
+ erase_extents (map, lo+1, 1);
+ }
+ else if (coalesce_below) {
+ /* Coalesce lo + new extent.
+ * => Extend lo to cover new extent.
+ */
+ map->extents[lo].length = offset + length - map->extents[lo].offset;
+ }
+ else if (coalesce_above) {
+ /* Coalesce new extent + lo+1
+ * => Extend lo+1 to cover new extent.
+ */
+ map->extents[lo+1].length =
+ map->extents[lo+1].offset + map->extents[lo+1].length - offset;
+ map->extents[lo+1].offset = offset;
+ }
+ else {
+ /* Normal case: Allocate a new extent and insert it after lo. */
+ new_extent.offset = offset;
+ new_extent.length = length;
+ new_extent.type = type;
+ if (insert_extent (map, new_extent, lo+1) == -1)
+ return -1;
+ }
+
+ return 0;
+}
+
+int
+nbdkit_extents_foreach (const struct nbdkit_extents_map *map,
+ nbdkit_extents_callback fn, void *opaque,
+ uint32_t flags,
+ uint64_t range_offset, uint64_t range_length)
+{
+ const bool flag_range = flags & NBDKIT_EXTENTS_FOREACH_FLAG_RANGE;
+ const bool flag_one = flags & NBDKIT_EXTENTS_FOREACH_FLAG_ONE;
+ uint64_t offset, next;
+ size_t i;
+
+ if (flag_range) {
+ if (range_offset + range_length < range_offset) {
+ nbdkit_error ("nbdkit_extents_foreach: invalid range: "
+ "offset=%" PRIu64 " length=%" PRIu64,
+ range_offset, range_length);
+ return -1;
+ }
+ }
+ else {
+ range_offset = 0;
+ range_length = INT64_MAX + UINT64_C(1);
+ }
+
+ for (i = 0, offset = range_offset;
+ offset < range_offset + range_length;
+ offset = next) {
+ next = offset;
+
+ if (i >= map->nr_extents) {
+ /* Beyond last extent => Type 0 to end of range. */
+ next = range_offset + range_length;
+ if (fn (offset, next - offset, 0, opaque) == -1)
+ return -1;
+ if (flag_one)
+ return 0;
+ continue;
+ }
+
+ if (offset < map->extents[i].offset) {
+ /* In a gap before the i'th extent => Type 0 to next offset. */
+ next = MIN (map->extents[i].offset, range_offset + range_length);
+ if (fn (offset, next - offset, 0, opaque) == -1)
+ return -1;
+ if (flag_one)
+ return 0;
+ continue;
+ }
+
+ if (offset < map->extents[i].offset + map->extents[i].length) {
+ /* In an extent. */
+ next = MIN (map->extents[i].offset + map->extents[i].length,
+ range_offset + range_length);
+ if (fn (offset, next - offset, map->extents[i].type, opaque) == -1)
+ return -1;
+ if (flag_one)
+ return 0;
+ continue;
+ }
+
+ /* After an extent, increment i and iterate. */
+ i++;
+ }
+
+ return 0;
+}
+
+#ifdef IN_TEST_EXTENTS
+/* These functions are only compiled for and called from the unit tests. */
+
+void
+dump_extents_map (const struct nbdkit_extents_map *map)
+{
+ size_t i;
+
+ fprintf (stderr, "map %p:\n", map);
+ fprintf (stderr, "\tnr_extents=%zu allocated=%zu\n",
+ map->nr_extents, map->allocated);
+ for (i = 0; i < map->nr_extents; ++i) {
+ fprintf (stderr, "\textent %zu:", i);
+ fprintf (stderr,
+ "\toffset=%" PRIu64 " length=%" PRIu64 " "
+ "last=%" PRIu64 " type=%" PRIu32 "\n",
+ map->extents[i].offset, map->extents[i].length,
+ map->extents[i].offset + map->extents[i].length - 1,
+ map->extents[i].type);
+ }
+}
+
+void
+validate_extents_map (const struct nbdkit_extents_map *map)
+{
+ size_t i;
+ bool fail = false;
+
+ if (map->nr_extents > map->allocated) {
+ fprintf (stderr, "validate_extents_map: nr_extents > allocated\n");
+ fail = true;
+ }
+
+ for (i = 0; i < map->nr_extents; ++i) {
+ /* Extent length must be > 0. */
+ if (map->extents[i].length == 0) {
+ fprintf (stderr, "validate_extents_map: %zu: extent length must be > 0\n",
+ i);
+ fail = true;
+ }
+
+ /* Extent length must not wrap around, indicating that we have
+ * computed a negative length (as unsigned) somewhere.
+ */
+ if (map->extents[i].offset + map->extents[i].length <
+ map->extents[i].offset) {
+ fprintf (stderr, "validate_extents_map: %zu: negative length\n",
+ i);
+ fail = true;
+ }
+
+ if (i > 0) {
+ /* Extents are stored in strictly ascending order. */
+ if (map->extents[i-1].offset >= map->extents[i].offset) {
+ fprintf (stderr,
+ "validate_extents_map: %zu: "
+ "not strictly ascending order\n", i);
+ fail = true;
+ }
+
+ /* Adjacent extents must not overlap. */
+ if (map->extents[i-1].offset + map->extents[i-1].length >
+ map->extents[i].offset) {
+ fprintf (stderr,
+ "validate_extents_map: %zu: "
+ "overlapping extents\n", i);
+ fail = true;
+ }
+
+ /* Adjacent extents either have a different type or are
+ * separated by a gap.
+ */
+ if (map->extents[i-1].type == map->extents[i].type &&
+ map->extents[i-1].offset + map->extents[i-1].length ==
+ map->extents[i].offset) {
+ fprintf (stderr,
+ "validate_extents_map: %zu: "
+ "adjacent extents with same type not coalesced\n", i);
+ fail = true;
+ }
+ }
+ }
+
+ if (fail) {
+ dump_extents_map (map);
+ abort ();
+ }
+}
+
+#endif /* IN_TEST_EXTENTS */
diff --git a/server/filters.c b/server/filters.c
index 5b7abc4..e284080 100644
--- a/server/filters.c
+++ b/server/filters.c
@@ -309,6 +309,13 @@ next_can_zero (void *nxdata)
return b_conn->b->can_zero (b_conn->b, b_conn->conn);
}
+static int
+next_can_extents (void *nxdata)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->can_extents (b_conn->b, b_conn->conn);
+}
+
static int
next_can_fua (void *nxdata)
{
@@ -364,6 +371,16 @@ next_zero (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags,
return b_conn->b->zero (b_conn->b, b_conn->conn, count, offset, flags, err);
}
+static int
+next_extents (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags,
+ struct nbdkit_extents_map *extents_map,
+ int *err)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->extents (b_conn->b, b_conn->conn, count, offset, flags,
+ extents_map, err);
+}
+
static struct nbdkit_next_ops next_ops = {
.get_size = next_get_size,
.can_write = next_can_write,
@@ -371,6 +388,7 @@ static struct nbdkit_next_ops next_ops = {
.is_rotational = next_is_rotational,
.can_trim = next_can_trim,
.can_zero = next_can_zero,
+ .can_extents = next_can_extents,
.can_fua = next_can_fua,
.can_multi_conn = next_can_multi_conn,
.pread = next_pread,
@@ -378,6 +396,7 @@ static struct nbdkit_next_ops next_ops = {
.flush = next_flush,
.trim = next_trim,
.zero = next_zero,
+ .extents = next_extents,
};
static int
@@ -511,6 +530,21 @@ filter_can_zero (struct backend *b, struct connection *conn)
return f->backend.next->can_zero (f->backend.next, conn);
}
+static int
+filter_can_extents (struct backend *b, struct connection *conn)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ debug ("%s: can_extents", f->name);
+
+ if (f->filter.can_extents)
+ return f->filter.can_extents (&next_ops, &nxdata, handle);
+ else
+ return f->backend.next->can_extents (f->backend.next, conn);
+}
+
static int
filter_can_fua (struct backend *b, struct connection *conn)
{
@@ -646,6 +680,31 @@ filter_zero (struct backend *b, struct connection *conn,
count, offset, flags, err);
}
+static int
+filter_extents (struct backend *b, struct connection *conn,
+ uint32_t count, uint64_t offset, uint32_t flags,
+ struct nbdkit_extents_map *extents_map,
+ int *err)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ assert (!(flags & ~NBDKIT_FLAG_REQ_ONE));
+
+ debug ("%s: extents count=%" PRIu32 " offset=%" PRIu64 " flags=0x%" PRIx32,
+ f->name, count, offset, flags);
+
+ if (f->filter.extents)
+ return f->filter.extents (&next_ops, &nxdata, handle,
+ count, offset, flags,
+ extents_map, err);
+ else
+ return f->backend.next->extents (f->backend.next, conn,
+ count, offset, flags,
+ extents_map, err);
+}
+
static struct backend filter_functions = {
.free = filter_free,
.thread_model = filter_thread_model,
@@ -667,6 +726,7 @@ static struct backend filter_functions = {
.is_rotational = filter_is_rotational,
.can_trim = filter_can_trim,
.can_zero = filter_can_zero,
+ .can_extents = filter_can_extents,
.can_fua = filter_can_fua,
.can_multi_conn = filter_can_multi_conn,
.pread = filter_pread,
@@ -674,6 +734,7 @@ static struct backend filter_functions = {
.flush = filter_flush,
.trim = filter_trim,
.zero = filter_zero,
+ .extents = filter_extents,
};
/* Register and load a filter. */
diff --git a/server/plugins.c b/server/plugins.c
index 28b96ad..0bd523b 100644
--- a/server/plugins.c
+++ b/server/plugins.c
@@ -1,5 +1,5 @@
/* nbdkit
- * Copyright (C) 2013-2018 Red Hat Inc.
+ * Copyright (C) 2013-2019 Red Hat Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -199,6 +199,8 @@ plugin_dump_fields (struct backend *b)
HAS (trim);
HAS (zero);
HAS (can_multi_conn);
+ HAS (can_extents);
+ HAS (extents);
#undef HAS
/* Custom fields. */
@@ -392,6 +394,21 @@ plugin_can_zero (struct backend *b, struct connection *conn)
return plugin_can_write (b, conn);
}
+static int
+plugin_can_extents (struct backend *b, struct connection *conn)
+{
+ struct backend_plugin *p = container_of (b, struct backend_plugin, backend);
+
+ assert (connection_get_handle (conn, 0));
+
+ debug ("can_extents");
+
+ if (p->plugin.can_extents)
+ return p->plugin.can_extents (connection_get_handle (conn, 0));
+ else
+ return p->plugin.extents != NULL;
+}
+
static int
plugin_can_fua (struct backend *b, struct connection *conn)
{
@@ -651,6 +668,41 @@ plugin_zero (struct backend *b, struct connection *conn,
return r;
}
+static int
+plugin_extents (struct backend *b, struct connection *conn,
+ uint32_t count, uint64_t offset, uint32_t flags,
+ struct nbdkit_extents_map *extents_map,
+ int *err)
+{
+ struct backend_plugin *p = container_of (b, struct backend_plugin, backend);
+ bool req_one = flags & NBDKIT_FLAG_REQ_ONE;
+ int r;
+
+ assert (connection_get_handle (conn, 0));
+ assert (!(flags & ~NBDKIT_FLAG_REQ_ONE));
+
+ debug ("extents count=%" PRIu32 " offset=%" PRIu64 " req_one=%d",
+ count, offset, req_one);
+
+ if (!count)
+ return 0;
+
+ if (p->plugin.extents) {
+ r = p->plugin.extents (connection_get_handle (conn, 0), count, offset,
+ flags, extents_map);
+ if (r == -1)
+ *err = get_error (p);
+ return r;
+ }
+ else {
+ /* By default we assume that everything in the range is allocated.
+ * However as that is the default state for the empty extents_map
+ * we don't need to do anything here.
+ */
+ return 0;
+ }
+}
+
static struct backend plugin_functions = {
.free = plugin_free,
.thread_model = plugin_thread_model,
@@ -672,6 +724,7 @@ static struct backend plugin_functions = {
.is_rotational = plugin_is_rotational,
.can_trim = plugin_can_trim,
.can_zero = plugin_can_zero,
+ .can_extents = plugin_can_extents,
.can_fua = plugin_can_fua,
.can_multi_conn = plugin_can_multi_conn,
.pread = plugin_pread,
@@ -679,6 +732,7 @@ static struct backend plugin_functions = {
.flush = plugin_flush,
.trim = plugin_trim,
.zero = plugin_zero,
+ .extents = plugin_extents,
};
/* Register and load a plugin. */
diff --git a/server/test-extents.c b/server/test-extents.c
new file mode 100644
index 0000000..e07ecda
--- /dev/null
+++ b/server/test-extents.c
@@ -0,0 +1,151 @@
+/* nbdkit
+ * Copyright (C) 2018-2019 Red Hat Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* Test the extents handling code (server/extents.c). This stochastic
+ * test works by allocating an array representing a disk, allocating
+ * extents randomly while writing the same information into the disk
+ * array, and then reading the extents back and comparing it to what's
+ * in the disk array.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <inttypes.h>
+#include <time.h>
+#include <assert.h>
+
+#include "minmax.h"
+#include "random.h"
+
+#include "internal.h"
+
+extern void dump_extents_map (const struct nbdkit_extents_map *map);
+extern void validate_extents_map (const struct nbdkit_extents_map *map);
+
+#define DISK_SIZE (1<<10)
+static uint8_t disk[DISK_SIZE];
+
+static bool error_flagged = false;
+
+/* Stub for linking against server/extents.c. */
+void
+nbdkit_error (const char *fs, ...)
+{
+ error_flagged = true;
+}
+
+static int
+compare (uint64_t offset, uint64_t length, uint32_t type, void *mapv)
+{
+ const struct nbdkit_extents_map *map = mapv;
+ size_t j;
+
+ /* nbdkit_extents_foreach_range should ensure this is true even if
+ * there are extents which go below or above the range.
+ */
+ assert (offset >= 0);
+ assert (offset + length <= DISK_SIZE);
+
+ fprintf (stderr,
+ "compare: offset=%" PRIu64 " length=%" PRIu64 " "
+ "type=%" PRIu32 "\n",
+ offset, length, type);
+
+ for (j = offset; j < offset+length; ++j) {
+ if (disk[j] != type) {
+ fprintf (stderr, "error: disk[%zu] != expected type %" PRIu32 "\n",
+ j, type);
+ dump_extents_map (map);
+ exit (EXIT_FAILURE);
+ }
+ }
+
+ return 0;
+}
+
+int
+main (int argc, char *argv[])
+{
+ unsigned i;
+ uint64_t offset, length;
+ uint32_t type;
+ size_t j;
+ struct random_state random_state;
+ struct nbdkit_extents_map *map;
+
+ xsrandom (time (NULL), &random_state);
+
+ map = nbdkit_extents_new ();
+ assert (map != NULL);
+
+ for (i = 0; i < 1000; ++i) {
+ type = xrandom (&random_state);
+ type &= 3;
+ offset = xrandom (&random_state);
+ offset &= DISK_SIZE - 1;
+ /* XXX Change the distribution so we mainly choose small lengths
+ * but with a small possibility of choosing large lengths.
+ */
+ length = xrandom (&random_state);
+ length &= DISK_SIZE/8 - 1;
+ length++;
+
+ fprintf (stderr,
+ "insert: extent offset=%" PRIu64 " length=%" PRIu64 " "
+ "type=%" PRIu32 "\n",
+ offset, length, type);
+
+ assert (nbdkit_extent_add (map, offset, length, type) == 0);
+
+ for (j = offset; j < MIN (offset+length, DISK_SIZE); ++j)
+ disk[j] = type;
+
+ /* Ask the extents code to validate that the invariants are still
+ * true. This calls abort(3) if not.
+ */
+ validate_extents_map (map);
+ dump_extents_map (map);
+ }
+
+ /* Read out the extents and compare them to the disk. */
+ assert (nbdkit_extents_foreach (map, compare, map,
+ NBDKIT_EXTENTS_FOREACH_FLAG_RANGE,
+ 0, DISK_SIZE-1) == 0);
+
+ nbdkit_extents_free (map);
+
+ exit (EXIT_SUCCESS);
+}
diff --git a/.gitignore b/.gitignore
index dc42abd..1f8b2e0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -63,6 +63,7 @@ Makefile.in
/server/nbdkit.pc
/server/protostrings.c
/server/synopsis.c
+/server/test-extents
/server/test-utils
/stamp-h1
/tests/disk
diff --git a/server/Makefile.am b/server/Makefile.am
index 5eb575e..5722f7b 100644
--- a/server/Makefile.am
+++ b/server/Makefile.am
@@ -43,6 +43,7 @@ nbdkit_SOURCES = \
connections.c \
crypto.c \
debug.c \
+ extents.c \
filters.c \
internal.h \
locks.c \
@@ -129,9 +130,22 @@ pkgconfig_DATA = nbdkit.pc
# Unit testing
-TESTS = test-utils
+TESTS = \
+ test-extents \
+ test-utils
-check_PROGRAMS = test-utils
+check_PROGRAMS = \
+ test-extents \
+ test-utils
+
+test_extents_SOURCES = \
+ test-extents.c \
+ extents.c
+test_extents_CPPFLAGS = \
+ -DIN_TEST_EXTENTS=1 \
+ -I$(top_srcdir)/include \
+ -I$(top_srcdir)/common/include
+test_extents_CFLAGS = $(WARNINGS_CFLAGS) $(VALGRIND_CFLAGS)
test_utils_SOURCES = \
test-utils.c \
--
2.20.1
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