[Qemu-block] [PATCH 1/4] IDE: Do not flush empty CDROM drives

[John Snow]

The block backend changed in a way that flushing empty CDROM drives
is now an error. Amend IDE to avoid doing so until the root problem
can be addressed for 2.11.

Reported-by: Kieron Shorrock <address@hidden>
Signed-off-by: John Snow <address@hidden>
---
 hw/ide/core.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 0b48b64..6cbca43 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1053,17 +1053,21 @@ static void ide_flush_cb(void *opaque, int ret)
     ide_set_irq(s->bus);
 }
 
-static void ide_flush_cache(IDEState *s)
+static bool ide_flush_cache(IDEState *s)
 {
     if (s->blk == NULL) {
         ide_flush_cb(s, 0);
-        return;
+        return false;
+    } else if (!blk_bs(s->blk)) {
+        /* Nothing to flush */
+        return true;
     }
 
     s->status |= BUSY_STAT;
     ide_set_retry(s);
     block_acct_start(blk_get_stats(s->blk), &s->acct, 0, BLOCK_ACCT_FLUSH);
     s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
+    return false;
 }
 
 static void ide_cfata_metadata_inquiry(IDEState *s)
@@ -1508,8 +1512,7 @@ static bool cmd_write_dma(IDEState *s, uint8_t cmd)
 
 static bool cmd_flush_cache(IDEState *s, uint8_t cmd)
 {
-    ide_flush_cache(s);
-    return false;
+    return ide_flush_cache(s);
 }
 
 static bool cmd_seek(IDEState *s, uint8_t cmd)
-- 
2.9.4