[Qemu-devel] [PATCH v2 03/17] block: add error parameter to bdrv_snapshot_goto() and related functions

[Pavel Hrdina]

Signed-off-by: Pavel Hrdina <address@hidden>
---
 block.c                | 27 ++++++++++++++++-----------
 block.h                |  3 ++-
 block/qcow2-snapshot.c | 15 ++++++++++++---
 block/qcow2.h          |  4 +++-
 block/rbd.c            |  6 +++++-
 block/sheepdog.c       | 14 +++++++-------
 block_int.h            |  3 ++-
 qemu-img.c             |  6 +-----
 savevm.c               |  2 +-
 9 files changed, 49 insertions(+), 31 deletions(-)

diff --git a/block.c b/block.c
index fea429b..d012b0e 100644
--- a/block.c
+++ b/block.c
@@ -3098,29 +3098,34 @@ int bdrv_snapshot_create(BlockDriverState *bs,
 }
 
 int bdrv_snapshot_goto(BlockDriverState *bs,
-                       const char *snapshot_id)
+                       const char *snapshot_id,
+                       Error **errp)
 {
     BlockDriver *drv = bs->drv;
     int ret, open_ret;
 
-    if (!drv)
-        return -ENOMEDIUM;
-    if (drv->bdrv_snapshot_goto)
-        return drv->bdrv_snapshot_goto(bs, snapshot_id);
-
-    if (bs->file) {
+    if (!drv) {
+        error_setg(errp, "Device '%s' has no medium.",
+                   bdrv_get_device_name(bs));
+        ret = -ENOMEDIUM;
+    } else if (drv->bdrv_snapshot_goto) {
+        ret = drv->bdrv_snapshot_goto(bs, snapshot_id, errp);
+    } else if (bs->file) {
         drv->bdrv_close(bs);
-        ret = bdrv_snapshot_goto(bs->file, snapshot_id);
+        ret = bdrv_snapshot_goto(bs->file, snapshot_id, errp);
         open_ret = drv->bdrv_open(bs, bs->open_flags);
         if (open_ret < 0) {
             bdrv_delete(bs->file);
             bs->drv = NULL;
-            return open_ret;
+            error_setg(errp, "Failed to open '%s'.", bdrv_get_device_name(bs));
+            ret = open_ret;
         }
-        return ret;
+    } else {
+        error_setg(errp, "Not supported.");
+        ret = -ENOTSUP;
     }
 
-    return -ENOTSUP;
+    return ret;
 }
 
 int bdrv_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
diff --git a/block.h b/block.h
index 6abb687..31642c2 100644
--- a/block.h
+++ b/block.h
@@ -324,7 +324,8 @@ int bdrv_snapshot_create(BlockDriverState *bs,
                          QEMUSnapshotInfo *sn_info,
                          Error **errp);
 int bdrv_snapshot_goto(BlockDriverState *bs,
-                       const char *snapshot_id);
+                       const char *snapshot_id,
+                       Error **errp);
 int bdrv_snapshot_delete(BlockDriverState *bs, const char *snapshot_id);
 int bdrv_snapshot_list(BlockDriverState *bs,
                        QEMUSnapshotInfo **psn_info);
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 3fd8aff..e07f9ac 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -428,7 +428,9 @@ fail:
 }
 
 /* copy the snapshot 'snapshot_name' into the current disk image */
-int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
+int qcow2_snapshot_goto(BlockDriverState *bs,
+                        const char *snapshot_id,
+                        Error **errp)
 {
     BDRVQcowState *s = bs->opaque;
     QCowSnapshot *sn;
@@ -440,13 +442,14 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char 
*snapshot_id)
     /* Search the snapshot */
     snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
     if (snapshot_index < 0) {
+        error_setg(errp, "Failed to find snapshot '%s' by id or name.",
+                   snapshot_id);
         return -ENOENT;
     }
     sn = &s->snapshots[snapshot_index];
 
     if (sn->disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) {
-        error_report("qcow2: Loading snapshots with different disk "
-            "size is not implemented");
+        error_setg(errp, "Not supported.");
         ret = -ENOTSUP;
         goto fail;
     }
@@ -458,6 +461,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char 
*snapshot_id)
      */
     ret = qcow2_grow_l1_table(bs, sn->l1_size, true);
     if (ret < 0) {
+        error_setg(errp, "Failed to grow L1 table.");
         goto fail;
     }
 
@@ -476,18 +480,21 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char 
*snapshot_id)
 
     ret = bdrv_pread(bs->file, sn->l1_table_offset, sn_l1_table, sn_l1_bytes);
     if (ret < 0) {
+        error_setg(errp, "Failed to load data into L1 table.");
         goto fail;
     }
 
     ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset,
                                          sn->l1_size, 1);
     if (ret < 0) {
+        error_setg(errp, "Failed to update snapshot refcount.");
         goto fail;
     }
 
     ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset, sn_l1_table,
                            cur_l1_bytes);
     if (ret < 0) {
+        error_setg(errp, "Failed to save L1 table.");
         goto fail;
     }
 
@@ -513,6 +520,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char 
*snapshot_id)
     }
 
     if (ret < 0) {
+        error_setg(errp, "Failed to update snapshot refcount.");
         goto fail;
     }
 
@@ -525,6 +533,7 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char 
*snapshot_id)
      */
     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 
0);
     if (ret < 0) {
+        error_setg(errp, "Failed to update snapshot refcount.");
         goto fail;
     }
 
diff --git a/block/qcow2.h b/block/qcow2.h
index 854bd12..6babb56 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -311,7 +311,9 @@ int qcow2_zero_clusters(BlockDriverState *bs, uint64_t 
offset, int nb_sectors);
 int qcow2_snapshot_create(BlockDriverState *bs,
                           QEMUSnapshotInfo *sn_info,
                           Error **errp);
-int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id);
+int qcow2_snapshot_goto(BlockDriverState *bs,
+                        const char *snapshot_id,
+                        Error **errp);
 int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id);
 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab);
 int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name);
diff --git a/block/rbd.c b/block/rbd.c
index cb5acf8..3e789c6 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -858,12 +858,16 @@ static int qemu_rbd_snap_remove(BlockDriverState *bs,
 }
 
 static int qemu_rbd_snap_rollback(BlockDriverState *bs,
-                                  const char *snapshot_name)
+                                  const char *snapshot_name,
+                                  Error **errp)
 {
     BDRVRBDState *s = bs->opaque;
     int r;
 
     r = rbd_snap_rollback(s->image, snapshot_name);
+    if (r < 0) {
+        error_setg(errp, "Failed to rollback snapshot.");
+    }
     return r;
 }
 
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 094634a..34ef75c 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -1808,7 +1808,9 @@ cleanup:
     return ret;
 }
 
-static int sd_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
+static int sd_snapshot_goto(BlockDriverState *bs,
+                            const char *snapshot_id,
+                            Error **errp)
 {
     BDRVSheepdogState *s = bs->opaque;
     BDRVSheepdogState *old_s;
@@ -1833,14 +1835,14 @@ static int sd_snapshot_goto(BlockDriverState *bs, const 
char *snapshot_id)
 
     ret = find_vdi_name(s, vdi, snapid, tag, &vid, 1);
     if (ret) {
-        error_report("Failed to find_vdi_name");
+        error_setg(errp, "Failed to find VDI snapshot '%s'.", vdi);
         goto out;
     }
 
     fd = connect_to_sdog(s->addr, s->port);
     if (fd < 0) {
-        error_report("failed to connect");
         ret = fd;
+        error_setg(errp, "Failed to connect to sdog.");
         goto out;
     }
 
@@ -1851,13 +1853,14 @@ static int sd_snapshot_goto(BlockDriverState *bs, const 
char *snapshot_id)
     closesocket(fd);
 
     if (ret) {
+        error_setg(errp, "Failed to open '%s'.", vdi);
         goto out;
     }
 
     memcpy(&s->inode, buf, sizeof(s->inode));
 
     if (!s->inode.vm_state_size) {
-        error_report("Invalid snapshot");
+        error_setg(errp, "Invalid snapshot '%s'.", snapshot_id);
         ret = -ENOENT;
         goto out;
     }
@@ -1873,9 +1876,6 @@ out:
     memcpy(s, old_s, sizeof(BDRVSheepdogState));
     g_free(buf);
     g_free(old_s);
-
-    error_report("failed to open. recover old bdrv_sd_state.");
-
     return ret;
 }
 
diff --git a/block_int.h b/block_int.h
index 976ea1f..016782c 100644
--- a/block_int.h
+++ b/block_int.h
@@ -150,7 +150,8 @@ struct BlockDriver {
                                 QEMUSnapshotInfo *sn_info,
                                 Error **errp);
     int (*bdrv_snapshot_goto)(BlockDriverState *bs,
-                              const char *snapshot_id);
+                              const char *snapshot_id,
+                              Error **errp);
     int (*bdrv_snapshot_delete)(BlockDriverState *bs, const char *snapshot_id);
     int (*bdrv_snapshot_list)(BlockDriverState *bs,
                               QEMUSnapshotInfo **psn_info);
diff --git a/qemu-img.c b/qemu-img.c
index 93e4022..91671a8 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1564,11 +1564,7 @@ static int img_snapshot(int argc, char **argv)
         break;
 
     case SNAPSHOT_APPLY:
-        ret = bdrv_snapshot_goto(bs, snapshot_name);
-        if (ret) {
-            error_report("Could not apply snapshot '%s': %d (%s)",
-                snapshot_name, ret, strerror(-ret));
-        }
+        ret = bdrv_snapshot_goto(bs, snapshot_name, &err);
         break;
 
     case SNAPSHOT_DELETE:
diff --git a/savevm.c b/savevm.c
index ef2f305..29e41fc 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2301,7 +2301,7 @@ int load_vmstate(const char *name)
     bs = NULL;
     while ((bs = bdrv_next(bs))) {
         if (bdrv_can_snapshot(bs)) {
-            ret = bdrv_snapshot_goto(bs, name);
+            ret = bdrv_snapshot_goto(bs, name, NULL);
             if (ret < 0) {
                 error_report("Error %d while activating snapshot '%s' on '%s'",
                              ret, name, bdrv_get_device_name(bs));
-- 
1.8.0.2