block: refactor bdrv_check_request: add errp

It's better to pass &error_abort than just assert that result is 0: on
crash, we'll immediately see the reason in the backtrace.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20201211183934.169161-2-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: fix iotest 206 fallout]
Signed-off-by: Eric Blake <eblake@redhat.com>

2 files changed, 23 insertions, 8 deletions

diff --git a/block/file-posix.c b/block/file-posix.c
index 11aafa9d82..05079b40ca 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -2969,7 +2969,7 @@ raw_do_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes,
 
         req->bytes = BDRV_MAX_LENGTH - req->offset;
 
-        assert(bdrv_check_request(req->offset, req->bytes) == 0);
+        bdrv_check_request(req->offset, req->bytes, &error_abort);
 
         bdrv_make_request_serialising(req, bs->bl.request_alignment);
     }
diff --git a/block/io.c b/block/io.c
index d203435a73..23abdae794 100644
--- a/block/io.c
+++ b/block/io.c
@@ -920,17 +920,34 @@ bool coroutine_fn bdrv_make_request_serialising(BdrvTrackedRequest *req,
     return waited;
 }
 
-int bdrv_check_request(int64_t offset, int64_t bytes)
+int bdrv_check_request(int64_t offset, int64_t bytes, Error **errp)
 {
-    if (offset < 0 || bytes < 0) {
+    if (offset < 0) {
+        error_setg(errp, "offset is negative: %" PRIi64, offset);
+        return -EIO;
+    }
+
+    if (bytes < 0) {
+        error_setg(errp, "bytes is negative: %" PRIi64, bytes);
         return -EIO;
     }
 
     if (bytes > BDRV_MAX_LENGTH) {
+        error_setg(errp, "bytes(%" PRIi64 ") exceeds maximum(%" PRIi64 ")",
+                   bytes, BDRV_MAX_LENGTH);
+        return -EIO;
+    }
+
+    if (offset > BDRV_MAX_LENGTH) {
+        error_setg(errp, "offset(%" PRIi64 ") exceeds maximum(%" PRIi64 ")",
+                   offset, BDRV_MAX_LENGTH);
         return -EIO;
     }
 
     if (offset > BDRV_MAX_LENGTH - bytes) {
+        error_setg(errp, "sum of offset(%" PRIi64 ") and bytes(%" PRIi64 ") "
+                   "exceeds maximum(%" PRIi64 ")", offset, bytes,
+                   BDRV_MAX_LENGTH);
         return -EIO;
     }
 
@@ -939,7 +956,7 @@ int bdrv_check_request(int64_t offset, int64_t bytes)
 
 static int bdrv_check_request32(int64_t offset, int64_t bytes)
 {
-    int ret = bdrv_check_request(offset, bytes);
+    int ret = bdrv_check_request(offset, bytes, NULL);
     if (ret < 0) {
         return ret;
     }
@@ -2847,7 +2864,7 @@ int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset,
         return -EPERM;
     }
 
-    ret = bdrv_check_request(offset, bytes);
+    ret = bdrv_check_request(offset, bytes, NULL);
     if (ret < 0) {
         return ret;
     }
@@ -3249,10 +3266,8 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
         return -EINVAL;
     }
 
-    ret = bdrv_check_request(offset, 0);
+    ret = bdrv_check_request(offset, 0, errp);
     if (ret < 0) {
-        error_setg(errp, "Required too big image size, it must be not greater "
-                   "than %" PRId64, BDRV_MAX_LENGTH);
         return ret;
     }