[Qemu-devel] [PATCH v7 03/20] block: Add and parse "lock-mode" option for image locking

[Fam Zheng <famz@redhat.com>]

Respect the locking mode from CLI or QMP, and set the open flags
accordingly.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block.c               | 21 +++++++++++++++++++++
 blockdev.c            |  9 +++++++++
 include/block/block.h |  1 +
 qemu-options.hx       |  1 +
 4 files changed, 32 insertions(+)

diff --git a/block.c b/block.c
index 30d64e6..5f76f60 100644
--- a/block.c
+++ b/block.c
@@ -705,6 +705,7 @@ static void bdrv_inherited_options(int *child_flags, QDict *child_options,
      * the parent. */
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
+    qdict_copy_default(child_options, parent_options, BDRV_OPT_LOCK_MODE);
 
     /* Our block drivers take care to send flushes and respect unmap policy,
      * so we can default to enable both on lower layers regardless of the
@@ -757,6 +758,7 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options,
      * which is only applied on the top level (BlockBackend) */
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
     qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
+    qdict_copy_default(child_options, parent_options, BDRV_OPT_LOCK_MODE);
 
     /* backing files always opened read-only */
     flags &= ~(BDRV_O_RDWR | BDRV_O_COPY_ON_READ);
@@ -880,6 +882,11 @@ static QemuOptsList bdrv_runtime_opts = {
             .name = BDRV_OPT_CACHE_NO_FLUSH,
             .type = QEMU_OPT_BOOL,
             .help = "Ignore flush requests",
+        },{
+            .name = BDRV_OPT_LOCK_MODE,
+            .type = QEMU_OPT_STRING,
+            .help = "how to lock the image (auto, shared, off. "
+                    "default: auto)",
         },
         { /* end of list */ }
     },
@@ -897,6 +904,7 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file,
     const char *filename;
     const char *driver_name = NULL;
     const char *node_name = NULL;
+    const char *lock_mode = NULL;
     QemuOpts *opts;
     BlockDriver *drv;
     Error *local_err = NULL;
@@ -940,6 +948,19 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file,
         goto fail_opts;
     }
 
+    lock_mode = qemu_opt_get(opts, BDRV_OPT_LOCK_MODE) ? : "off";
+    if (!strcmp(lock_mode, "auto")) {
+        /* Default */
+    } else if (!strcmp(lock_mode, "shared")) {
+        bs->open_flags |= BDRV_O_SHARED_LOCK;
+    } else if (!strcmp(lock_mode, "off")) {
+        bs->open_flags |= BDRV_O_NO_LOCK;
+    } else {
+        error_setg(errp, "invalid lock mode");
+        ret = -EINVAL;
+        goto fail_opts;
+    }
+
     bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
 
     if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) {
diff --git a/blockdev.c b/blockdev.c
index 2161400..a9032b9 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -545,6 +545,10 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
         qdict_put(bs_opts, "driver", qstring_from_str(buf));
     }
 
+    if ((buf = qemu_opt_get(opts, BDRV_OPT_LOCK_MODE)) != NULL) {
+        qdict_put(bs_opts, BDRV_OPT_LOCK_MODE, qstring_from_str(buf));
+    }
+
     on_write_error = BLOCKDEV_ON_ERROR_ENOSPC;
     if ((buf = qemu_opt_get(opts, "werror")) != NULL) {
         on_write_error = parse_block_error_action(buf, 0, &error);
@@ -4265,6 +4269,11 @@ QemuOptsList qemu_common_drive_opts = {
             .type = QEMU_OPT_BOOL,
             .help = "whether to account for failed I/O operations "
                     "in the statistics",
+        },{
+            .name = BDRV_OPT_LOCK_MODE,
+            .type = QEMU_OPT_STRING,
+            .help = "how to lock the image (auto, shared, off. "
+                    "default: auto)",
         },
         { /* end of list */ }
     },
diff --git a/include/block/block.h b/include/block/block.h
index 4f8450b..a14101b 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -108,6 +108,7 @@ typedef struct HDGeometry {
 #define BDRV_OPT_CACHE_WB       "cache.writeback"
 #define BDRV_OPT_CACHE_DIRECT   "cache.direct"
 #define BDRV_OPT_CACHE_NO_FLUSH "cache.no-flush"
+#define BDRV_OPT_LOCK_MODE      "lock-mode"
 
 
 #define BDRV_SECTOR_BITS   9
diff --git a/qemu-options.hx b/qemu-options.hx
index a71aaf8..0f67b64 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -521,6 +521,7 @@ DEF("drive", HAS_ARG, QEMU_OPTION_drive,
     "       [,werror=ignore|stop|report|enospc][,id=name][,aio=threads|native]\n"
     "       [,readonly=on|off][,copy-on-read=on|off]\n"
     "       [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
+    "       [,lock-mode=auto|shared|off]\n"
     "       [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
     "       [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
     "       [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
-- 
2.7.4