[PULL 16/17] block/qed: bdrv_qed_do_open: deal with errp

[Eric Blake <eblake@redhat.com>]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Always set errp on failure. The generic bdrv_open_driver supports
driver functions which can return a negative value but forget to set
errp.  That's a strange thing. Let's improve bdrv_qed_do_open to not
behave this way. This allows the simplification of code in
bdrv_qed_co_invalidate_cache().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210202124956.63146-14-vsementsov@virtuozzo.com>
[eblake: commit message grammar tweak]
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 block/qed.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/block/qed.c b/block/qed.c
index b27e7546cabd..f45c640513f5 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -393,6 +393,7 @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,

     ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header));
     if (ret < 0) {
+        error_setg(errp, "Failed to read QED header");
         return ret;
     }
     qed_header_le_to_cpu(&le_header, &s->header);
@@ -408,25 +409,30 @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,
         return -ENOTSUP;
     }
     if (!qed_is_cluster_size_valid(s->header.cluster_size)) {
+        error_setg(errp, "QED cluster size is invalid");
         return -EINVAL;
     }

     /* Round down file size to the last cluster */
     file_size = bdrv_getlength(bs->file->bs);
     if (file_size < 0) {
+        error_setg(errp, "Failed to get file length");
         return file_size;
     }
     s->file_size = qed_start_of_cluster(s, file_size);

     if (!qed_is_table_size_valid(s->header.table_size)) {
+        error_setg(errp, "QED table size is invalid");
         return -EINVAL;
     }
     if (!qed_is_image_size_valid(s->header.image_size,
                                  s->header.cluster_size,
                                  s->header.table_size)) {
+        error_setg(errp, "QED image size is invalid");
         return -EINVAL;
     }
     if (!qed_check_table_offset(s, s->header.l1_table_offset)) {
+        error_setg(errp, "QED table offset is invalid");
         return -EINVAL;
     }

@@ -438,6 +444,7 @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,

     /* Header size calculation must not overflow uint32_t */
     if (s->header.header_size > UINT32_MAX / s->header.cluster_size) {
+        error_setg(errp, "QED header size is too large");
         return -EINVAL;
     }

@@ -445,6 +452,7 @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,
         if ((uint64_t)s->header.backing_filename_offset +
             s->header.backing_filename_size >
             s->header.cluster_size * s->header.header_size) {
+            error_setg(errp, "QED backing filename offset is invalid");
             return -EINVAL;
         }

@@ -453,6 +461,7 @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,
                               bs->auto_backing_file,
                               sizeof(bs->auto_backing_file));
         if (ret < 0) {
+            error_setg(errp, "Failed to read backing filename");
             return ret;
         }
         pstrcpy(bs->backing_file, sizeof(bs->backing_file),
@@ -475,6 +484,7 @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,

         ret = qed_write_header_sync(s);
         if (ret) {
+            error_setg(errp, "Failed to update header");
             return ret;
         }

@@ -487,6 +497,7 @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,

     ret = qed_read_l1_table_sync(s);
     if (ret) {
+        error_setg(errp, "Failed to read L1 table");
         goto out;
     }

@@ -503,6 +514,7 @@ static int coroutine_fn bdrv_qed_do_open(BlockDriverState *bs, QDict *options,

             ret = qed_check(s, &result, true);
             if (ret) {
+                error_setg(errp, "Image corrupted");
                 goto out;
             }
         }
@@ -1537,22 +1549,16 @@ static void coroutine_fn bdrv_qed_co_invalidate_cache(BlockDriverState *bs,
                                                       Error **errp)
 {
     BDRVQEDState *s = bs->opaque;
-    Error *local_err = NULL;
     int ret;

     bdrv_qed_close(bs);

     bdrv_qed_init_state(bs);
     qemu_co_mutex_lock(&s->table_lock);
-    ret = bdrv_qed_do_open(bs, NULL, bs->open_flags, &local_err);
+    ret = bdrv_qed_do_open(bs, NULL, bs->open_flags, errp);
     qemu_co_mutex_unlock(&s->table_lock);
-    if (local_err) {
-        error_propagate_prepend(errp, local_err,
-                                "Could not reopen qed layer: ");
-        return;
-    } else if (ret < 0) {
-        error_setg_errno(errp, -ret, "Could not reopen qed layer");
-        return;
+    if (ret < 0) {
+        error_prepend(errp, "Could not reopen qed layer: ");
     }
 }

-- 
2.30.1