[Qemu-devel] [PATCH V9 02/14] block: distinguish id and name in bdrv_find_snapshot()

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

  To make it clear about id and name in searching, the API is changed
a bit to distinguish them, and caller can choose to search by id or name.
Searching will be done with higher priority of id. This function also
returns negative value from bdrv_snapshot_list() instead of -ENOENT on
error now.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 block/snapshot.c         |   46 ++++++++++++++++++++++++++++++++++++++--------
 include/block/snapshot.h |    2 +-
 savevm.c                 |   10 +++++-----
 3 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index 8de73b4..1449b3d 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -13,8 +13,20 @@
 
 #include "block/snapshot.h"
 
+/*
+ * Try find an internal snapshot with @id or @name, @id have higher priority
+ * in searching.
+ *
+ * @bs: block device to search on, must not be NULL.
+ * @sn_info: snapshot information to be filled in, must not be NULL.
+ * @id: snapshot id to search with, can be NULL.
+ * @name: snapshot name to search with, can be NULL.
+ *
+ * returns 0 and @sn_info is filled with related information if found,
+ * otherwise it returns negative value.
+ */
 int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
-                       const char *name)
+                       const char *id, const char *name)
 {
     QEMUSnapshotInfo *sn_tab, *sn;
     int nb_sns, i, ret;
@@ -22,16 +34,34 @@ int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
     ret = -ENOENT;
     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
     if (nb_sns < 0) {
-        return ret;
+        return nb_sns;
     }
-    for (i = 0; i < nb_sns; i++) {
-        sn = &sn_tab[i];
-        if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
-            *sn_info = *sn;
-            ret = 0;
-            break;
+
+    /* search by id */
+    if (id) {
+        for (i = 0; i < nb_sns; i++) {
+            sn = &sn_tab[i];
+            if (!strcmp(sn->id_str, id)) {
+                *sn_info = *sn;
+                ret = 0;
+                goto out;
+            }
         }
     }
+
+    /* search by name */
+    if (name) {
+        for (i = 0; i < nb_sns; i++) {
+            sn = &sn_tab[i];
+            if (!strcmp(sn->name, name)) {
+                *sn_info = *sn;
+                ret = 0;
+                goto out;
+            }
+        }
+    }
+
+ out:
     g_free(sn_tab);
     return ret;
 }
diff --git a/include/block/snapshot.h b/include/block/snapshot.h
index 86891d1..fc9be7b 100644
--- a/include/block/snapshot.h
+++ b/include/block/snapshot.h
@@ -22,5 +22,5 @@
 #include "block.h"
 
 int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
-                       const char *name);
+                       const char *id, const char *name);
 #endif
diff --git a/savevm.c b/savevm.c
index 95f19ca..6557750 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2073,7 +2073,7 @@ static int del_existing_snapshots(Monitor *mon, const char *name)
     bs = NULL;
     while ((bs = bdrv_next(bs))) {
         if (bdrv_can_snapshot(bs) &&
-            bdrv_snapshot_find(bs, snapshot, name) >= 0)
+            bdrv_snapshot_find(bs, snapshot, name, name) >= 0)
         {
             ret = bdrv_snapshot_delete(bs, name);
             if (ret < 0) {
@@ -2133,7 +2133,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
     sn->vm_clock_nsec = qemu_get_clock_ns(vm_clock);
 
     if (name) {
-        ret = bdrv_snapshot_find(bs, old_sn, name);
+        ret = bdrv_snapshot_find(bs, old_sn, name, name);
         if (ret >= 0) {
             pstrcpy(sn->name, sizeof(sn->name), old_sn->name);
             pstrcpy(sn->id_str, sizeof(sn->id_str), old_sn->id_str);
@@ -2224,7 +2224,7 @@ int load_vmstate(const char *name)
     }
 
     /* Don't even try to load empty VM states */
-    ret = bdrv_snapshot_find(bs_vm_state, &sn, name);
+    ret = bdrv_snapshot_find(bs_vm_state, &sn, name, name);
     if (ret < 0) {
         return ret;
     } else if (sn.vm_state_size == 0) {
@@ -2248,7 +2248,7 @@ int load_vmstate(const char *name)
             return -ENOTSUP;
         }
 
-        ret = bdrv_snapshot_find(bs, &sn, name);
+        ret = bdrv_snapshot_find(bs, &sn, name, name);
         if (ret < 0) {
             error_report("Device '%s' does not have the requested snapshot '%s'",
                            bdrv_get_device_name(bs), name);
@@ -2354,7 +2354,7 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
 
         while ((bs1 = bdrv_next(bs1))) {
             if (bdrv_can_snapshot(bs1) && bs1 != bs) {
-                ret = bdrv_snapshot_find(bs1, sn_info, sn->id_str);
+                ret = bdrv_snapshot_find(bs1, sn_info, sn->id_str, NULL);
                 if (ret < 0) {
                     available = 0;
                     break;
-- 
1.7.1