[PULL,02/24] block: Move read-only check during truncation earlier

Commit Message

Kevin Wolf June 30, 2021, 4:01 p.m. UTC

From: Eric Blake <[e-mail]>

No need to start a tracked request that will always fail.  The choice
to check read-only after bdrv_inc_in_flight() predates 1bc5f09f2e
(block: Use tracked request for truncate), but waiting for serializing
requests can make the effect more noticeable.

Signed-off-by: Eric Blake <[e-mail]>
Message-Id: <[e-mail]>
Reviewed-by: Vladimir Sementsov-Ogievskiy <[e-mail]>
Signed-off-by: Kevin Wolf <[e-mail]>
---
 block/io.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

Patch

diff --git a/block/io.c b/block/io.c
index dd93364258..cf177a9d2d 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3392,6 +3392,11 @@  int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
         return old_size;
     }
 
+    if (bdrv_is_read_only(bs)) {
+        error_setg(errp, "Image is read-only");
+        return -EACCES;
+    }
+
     if (offset > old_size) {
         new_bytes = offset - old_size;
     } else {
@@ -3408,11 +3413,6 @@  int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
     if (new_bytes) {
         bdrv_make_request_serialising(&req, 1);
     }
-    if (bdrv_is_read_only(bs)) {
-        error_setg(errp, "Image is read-only");
-        ret = -EACCES;
-        goto out;
-    }
     ret = bdrv_co_write_req_prepare(child, offset - new_bytes, new_bytes, &req,
                                     0);
     if (ret < 0) {