[Qemu-devel] [PATCH] file-posix: Fix has_write_zeroes after NO_FALLBACK

* [Qemu-devel] [PATCH] file-posix: Fix has_write_zeroes after NO_FALLBACK
@ 2019-08-16  9:55 Kevin Wolf
  2019-08-17 14:37 ` Eric Blake
  0 siblings, 1 reply; 2+ messages in thread
From: Kevin Wolf @ 2019-08-16  9:55 UTC (permalink / raw)
  To: qemu-block; +Cc: kwolf, qemu-devel, mreitz

If QEMU_AIO_NO_FALLBACK is given, we always return failure and don't
even try to use the BLKZEROOUT ioctl. In this failure case, we shouldn't
disable has_write_zeroes because we didn't learn anything about the
ioctl. The next request might not set QEMU_AIO_NO_FALLBACK and we can
still use the ioctl then.

Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/file-posix.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index b8b4dad553..e927f9d3c3 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1555,12 +1555,12 @@ static ssize_t handle_aiocb_write_zeroes_block(RawPosixAIOData *aiocb)
         } while (errno == EINTR);
 
         ret = translate_err(-errno);
+        if (ret == -ENOTSUP) {
+            s->has_write_zeroes = false;
+        }
     }
 #endif
 
-    if (ret == -ENOTSUP) {
-        s->has_write_zeroes = false;
-    }
     return ret;
 }
 
-- 
2.20.1



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