[Qemu-devel] [PATCH for-2.2 2/2] qemu-nbd: add option to set detect-zeroes mode

[Peter Lieven <pl@kamp.de>]

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 qemu-nbd.c |   81 +++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 53 insertions(+), 28 deletions(-)

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 626e584..75cf54f 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -18,11 +18,13 @@
 
 #include "qemu-common.h"
 #include "block/block.h"
+#include "block/block_int.h"
 #include "block/nbd.h"
 #include "qemu/main-loop.h"
 #include "qemu/sockets.h"
 #include "qemu/error-report.h"
 #include "block/snapshot.h"
+#include "qapi/util.h"
 
 #include <stdarg.h>
 #include <stdio.h>
@@ -38,9 +40,10 @@
 #include <pthread.h>
 
 #define SOCKET_PATH          "/var/lock/qemu-nbd-%s"
-#define QEMU_NBD_OPT_CACHE   1
-#define QEMU_NBD_OPT_AIO     2
-#define QEMU_NBD_OPT_DISCARD 3
+#define QEMU_NBD_OPT_CACHE         1
+#define QEMU_NBD_OPT_AIO           2
+#define QEMU_NBD_OPT_DISCARD       3
+#define QEMU_NBD_OPT_DETECT_ZEROES 4
 
 static NBDExport *exp;
 static int verbose;
@@ -57,45 +60,47 @@ static void usage(const char *name)
 "Usage: %s [OPTIONS] FILE\n"
 "QEMU Disk Network Block Device Server\n"
 "\n"
-"  -h, --help           display this help and exit\n"
-"  -V, --version        output version information and exit\n"
+"  -h, --help                display this help and exit\n"
+"  -V, --version             output version information and exit\n"
 "\n"
 "Connection properties:\n"
-"  -p, --port=PORT      port to listen on (default `%d')\n"
-"  -b, --bind=IFACE     interface to bind to (default `0.0.0.0')\n"
-"  -k, --socket=PATH    path to the unix socket\n"
-"                       (default '"SOCKET_PATH"')\n"
-"  -e, --shared=NUM     device can be shared by NUM clients (default '1')\n"
-"  -t, --persistent     don't exit on the last connection\n"
-"  -v, --verbose        display extra debugging information\n"
+"  -p, --port=PORT           port to listen on (default `%d')\n"
+"  -b, --bind=IFACE          interface to bind to (default `0.0.0.0')\n"
+"  -k, --socket=PATH         path to the unix socket\n"
+"                            (default '"SOCKET_PATH"')\n"
+"  -e, --shared=NUM          device can be shared by NUM clients (default '1')\n"
+"  -t, --persistent          don't exit on the last connection\n"
+"  -v, --verbose             display extra debugging information\n"
 "\n"
 "Exposing part of the image:\n"
-"  -o, --offset=OFFSET  offset into the image\n"
-"  -P, --partition=NUM  only expose partition NUM\n"
+"  -o, --offset=OFFSET       offset into the image\n"
+"  -P, --partition=NUM       only expose partition NUM\n"
 "\n"
 #ifdef __linux__
 "Kernel NBD client support:\n"
-"  -c, --connect=DEV    connect FILE to the local NBD device DEV\n"
-"  -d, --disconnect     disconnect the specified device\n"
+"  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"
+"  -d, --disconnect          disconnect the specified device\n"
 "\n"
 #endif
 "\n"
 "Block device options:\n"
-"  -f, --format=FORMAT  set image format (raw, qcow2, ...)\n"
-"  -r, --read-only      export read-only\n"
-"  -s, --snapshot       use FILE as an external snapshot, create a temporary\n"
-"                       file with backing_file=FILE, redirect the write to\n"
-"                       the temporary one\n"
+"  -f, --format=FORMAT       set image format (raw, qcow2, ...)\n"
+"  -r, --read-only           export read-only\n"
+"  -s, --snapshot            use FILE as an external snapshot, create a temporary\n"
+"                            file with backing_file=FILE, redirect the write to\n"
+"                            the temporary one\n"
 "  -l, --load-snapshot=SNAPSHOT_PARAM\n"
-"                       load an internal snapshot inside FILE and export it\n"
-"                       as an read-only device, SNAPSHOT_PARAM format is\n"
-"                       'snapshot.id=[ID],snapshot.name=[NAME]', or\n"
-"                       '[ID_OR_NAME]'\n"
-"  -n, --nocache        disable host cache\n"
-"      --cache=MODE     set cache mode (none, writeback, ...)\n"
+"                            load an internal snapshot inside FILE and export it\n"
+"                            as an read-only device, SNAPSHOT_PARAM format is\n"
+"                            'snapshot.id=[ID],snapshot.name=[NAME]', or\n"
+"                            '[ID_OR_NAME]'\n"
+"  -n, --nocache             disable host cache\n"
+"      --cache=MODE          set cache mode (none, writeback, ...)\n"
 #ifdef CONFIG_LINUX_AIO
-"      --aio=MODE       set AIO mode (native or threads)\n"
+"      --aio=MODE            set AIO mode (native or threads)\n"
 #endif
+"      --discard=MODE        set discard mode (ignore, unmap)\n"
+"      --detect-zeroes=MODE  set detect-zeroes mode (off, on, discard)\n"
 "\n"
 "Report bugs to <qemu-devel@nongnu.org>\n"
     , name, NBD_DEFAULT_PORT, "DEVICE");
@@ -410,6 +415,7 @@ int main(int argc, char **argv)
         { "aio", 1, NULL, QEMU_NBD_OPT_AIO },
 #endif
         { "discard", 1, NULL, QEMU_NBD_OPT_DISCARD },
+        { "detect-zeroes", 1, NULL, QEMU_NBD_OPT_DETECT_ZEROES },
         { "shared", 1, NULL, 'e' },
         { "format", 1, NULL, 'f' },
         { "persistent", 0, NULL, 't' },
@@ -432,6 +438,7 @@ int main(int argc, char **argv)
     pthread_t client_thread;
     const char *fmt = NULL;
     Error *local_err = NULL;
+    BlockdevDetectZeroesOptions detect_zeroes = BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF;
 
     /* The client thread uses SIGTERM to interrupt the server.  A signal
      * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
@@ -483,6 +490,23 @@ int main(int argc, char **argv)
                 errx(EXIT_FAILURE, "Invalid discard mode `%s'", optarg);
             }
             break;
+        case QEMU_NBD_OPT_DETECT_ZEROES:
+            detect_zeroes =
+                qapi_enum_parse(BlockdevDetectZeroesOptions_lookup,
+                                optarg,
+                                BLOCKDEV_DETECT_ZEROES_OPTIONS_MAX,
+                                BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF,
+                                &local_err);
+            if (local_err) {
+                errx(EXIT_FAILURE, "Failed to parse detect_zeroes mode: %s",
+                     error_get_pretty(local_err));
+            }
+            if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
+                !(flags & BDRV_O_UNMAP)) {
+                errx(EXIT_FAILURE, "setting detect-zeroes to unmap is not allowed "
+                                   "without setting discard operation to unmap");
+            }
+            break;
         case 'b':
             bindto = optarg;
             break;
@@ -686,6 +710,7 @@ int main(int argc, char **argv)
             error_get_pretty(local_err));
     }
 
+    bs->detect_zeroes = detect_zeroes;
     fd_size = bdrv_getlength(bs);
 
     if (partition != -1) {
-- 
1.7.9.5