block-backend: remove blk_flush_all

We can teach Xen to drain and flush each device as it needs to, instead
of trying to flush ALL devices. This removes the last user of
blk_flush_all.

The function is therefore removed under the premise that any new uses
of blk_flush_all would be the wrong paradigm: either flush the single
device that requires flushing, or use an appropriate flush_all mechanism
from outside of the BlkBackend layer.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/block-backend.c

@@ -1640,28 +1640,6 @@ int blk_commit_all(void)
     return 0;
 }
 
-int blk_flush_all(void)
-{
-    BlockBackend *blk = NULL;
-    int result = 0;
-
-    while ((blk = blk_all_next(blk)) != NULL) {
-        AioContext *aio_context = blk_get_aio_context(blk);
-        int ret;
-
-        aio_context_acquire(aio_context);
-        if (blk_is_inserted(blk)) {
-            ret = blk_flush(blk);
-            if (ret < 0 && !result) {
-                result = ret;
-            }
-        }
-        aio_context_release(aio_context);
-    }
-
-    return result;
-}
-
 
 /* throttling disk I/O limits */
 void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg)

hw/i386/xen/xen_platform.c

@@ -134,8 +134,6 @@ static void platform_fixed_ioport_writew(void *opaque, uint32_t addr, uint32_t v
            devices, and bit 2 the non-primary-master IDE devices. */
         if (val & UNPLUG_ALL_IDE_DISKS) {
             DPRINTF("unplug disks\n");
-            blk_drain_all();
-            blk_flush_all();
             pci_unplug_disks(pci_dev->bus);
         }
         if (val & UNPLUG_ALL_NICS) {

hw/ide/piix.c

@@ -179,6 +179,10 @@ int pci_piix3_xen_ide_unplug(DeviceState *dev)
         if (di != NULL && !di->media_cd) {
             BlockBackend *blk = blk_by_legacy_dinfo(di);
             DeviceState *ds = blk_get_attached_dev(blk);
+
+            blk_drain(blk);
+            blk_flush(blk);
+
             if (ds) {
                 blk_detach_dev(blk, ds);
             }

include/sysemu/block-backend.h

@@ -152,7 +152,6 @@ BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
 int blk_co_pdiscard(BlockBackend *blk, int64_t offset, int count);
 int blk_co_flush(BlockBackend *blk);
 int blk_flush(BlockBackend *blk);
-int blk_flush_all(void);
 int blk_commit_all(void);
 void blk_drain(BlockBackend *blk);
 void blk_drain_all(void);