Merge remote-tracking branch 'remotes/jnsnow/tags/ide-pull-request' into staging

# gpg: Signature made Mon 18 Jul 2016 23:53:15 BST
# gpg:                using RSA key 0x7DEF8106AAFC390E
# gpg: Good signature from "John Snow (John Huston) <jsnow@redhat.com>"
# Primary key fingerprint: FAEB 9711 A12C F475 812F  18F2 88A9 064D 1835 61EB
#      Subkey fingerprint: F9B7 ABDB BCAC DF95 BE76  CBD0 7DEF 8106 AAFC 390E

* remotes/jnsnow/tags/ide-pull-request:
  block: ignore flush requests when storage is clean
  tests: in IDE and AHCI tests perform DMA write before flushing
  ide: set retry_unit for PIO and FLUSH requests
  ide: refactor retry_unit set and clear into separate function

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/block/io.c b/block/io.c
index 2887394633..cfda7148d8 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1303,6 +1303,7 @@ static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
     }
     bdrv_debug_event(bs, BLKDBG_PWRITEV_DONE);
 
+    ++bs->write_gen;
     bdrv_set_dirty(bs, start_sector, end_sector - start_sector);
 
     if (bs->wr_highest_offset < offset + bytes) {
@@ -2236,6 +2237,15 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
 
     tracked_request_begin(&req, bs, 0, 0, BDRV_TRACKED_FLUSH);
 
+    int current_gen = bs->write_gen;
+
+    /* Wait until any previous flushes are completed */
+    while (bs->flush_started_gen != bs->flushed_gen) {
+        qemu_co_queue_wait(&bs->flush_queue);
+    }
+
+    bs->flush_started_gen = current_gen;
+
     /* Write back all layers by calling one driver function */
     if (bs->drv->bdrv_co_flush) {
         ret = bs->drv->bdrv_co_flush(bs);
@@ -2256,6 +2266,11 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
         goto flush_parent;
     }
 
+    /* Check if we really need to flush anything */
+    if (bs->flushed_gen == current_gen) {
+        goto flush_parent;
+    }
+
     BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK);
     if (bs->drv->bdrv_co_flush_to_disk) {
         ret = bs->drv->bdrv_co_flush_to_disk(bs);
@@ -2286,6 +2301,7 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
          */
         ret = 0;
     }
+
     if (ret < 0) {
         goto out;
     }
@@ -2296,6 +2312,10 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
 flush_parent:
     ret = bs->file ? bdrv_co_flush(bs->file->bs) : 0;
 out:
+    /* Notify any pending flushes that we have completed */
+    bs->flushed_gen = current_gen;
+    qemu_co_queue_restart_all(&bs->flush_queue);
+
     tracked_request_end(&req);
     return ret;
 }
@@ -2421,6 +2441,7 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
     }
     ret = 0;
 out:
+    ++bs->write_gen;
     bdrv_set_dirty(bs, req.offset >> BDRV_SECTOR_BITS,
                    req.bytes >> BDRV_SECTOR_BITS);
     tracked_request_end(&req);