block: fix snapshot on QED

QED's opaque data includes a pointer back to the BlockDriverState.
This breaks when bdrv_append shuffles data between bs_new and bs_top.
To avoid this, add a "rebind" function that tells the driver about
the new relationship between the BlockDriverState and its opaque.

The patch also adds rebind to VVFAT for completeness, even though
it is not used with live snapshots.

Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block.c b/block.c
index 3db84cd241e9cb4a58e767a6240e91b9c431d207..87600a54dd92df09ab66534293b49bd6aba8d1ca 100644 (file)
--- a/block.c
+++ b/block.c
@@ -949,6 +949,13 @@ void bdrv_make_anon(BlockDriverState *bs)
     bs->device_name[0] = '\0';
 }
 
+static void bdrv_rebind(BlockDriverState *bs)
+{
+    if (bs->drv && bs->drv->bdrv_rebind) {
+        bs->drv->bdrv_rebind(bs);
+    }
+}
+
 /*
  * Add new bs contents at the top of an image chain while the chain is
  * live, while keeping required fields on the top layer.
@@ -1037,6 +1044,9 @@ void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top)
     bs_new->slice_time        = 0;
     bs_new->slice_start       = 0;
     bs_new->slice_end         = 0;
+
+    bdrv_rebind(bs_new);
+    bdrv_rebind(bs_top);
 }
 
 void bdrv_delete(BlockDriverState *bs)

diff --git a/block/qed.c b/block/qed.c
index 366cde7ad83fa4c1087e439c1ea017f7e1b2f137..30a31f907f2d03721214971198f7109a88325fcf 100644 (file)
--- a/block/qed.c
+++ b/block/qed.c
@@ -367,6 +367,12 @@ static void qed_cancel_need_check_timer(BDRVQEDState *s)
     qemu_del_timer(s->need_check_timer);
 }
 
+static void bdrv_qed_rebind(BlockDriverState *bs)
+{
+    BDRVQEDState *s = bs->opaque;
+    s->bs = bs;
+}
+
 static int bdrv_qed_open(BlockDriverState *bs, int flags)
 {
     BDRVQEDState *s = bs->opaque;
@@ -1550,6 +1556,7 @@ static BlockDriver bdrv_qed = {
     .create_options           = qed_create_options,
 
     .bdrv_probe               = bdrv_qed_probe,
+    .bdrv_rebind              = bdrv_qed_rebind,
     .bdrv_open                = bdrv_qed_open,
     .bdrv_close               = bdrv_qed_close,
     .bdrv_create              = bdrv_qed_create,

diff --git a/block/vvfat.c b/block/vvfat.c
index 9ef21ddfc5ec7d6a18643f872dc2811356f03b6f..2dc9d50888585eb2978ed43322d2af88539f986d 100644 (file)
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -982,6 +982,12 @@ static BDRVVVFATState *vvv = NULL;
 static int enable_write_target(BDRVVVFATState *s);
 static int is_consistent(BDRVVVFATState *s);
 
+static void vvfat_rebind(BlockDriverState *bs)
+{
+    BDRVVVFATState *s = bs->opaque;
+    s->bs = bs;
+}
+
 static int vvfat_open(BlockDriverState *bs, const char* dirname, int flags)
 {
     BDRVVVFATState *s = bs->opaque;
@@ -2855,6 +2861,7 @@ static BlockDriver bdrv_vvfat = {
     .format_name       = "vvfat",
     .instance_size     = sizeof(BDRVVVFATState),
     .bdrv_file_open    = vvfat_open,
+    .bdrv_rebind       = vvfat_rebind,
     .bdrv_read          = vvfat_co_read,
     .bdrv_write         = vvfat_co_write,
     .bdrv_close                = vvfat_close,

diff --git a/block_int.h b/block_int.h
index 086832aab91165e9719c29e7272f2aee64cbe760..fbbc7aeb1a644baf7cd8754ccac59649d78b935f 100644 (file)
--- a/block_int.h
+++ b/block_int.h
@@ -140,6 +140,7 @@ struct BlockDriver {
     int (*bdrv_write)(BlockDriverState *bs, int64_t sector_num,
                       const uint8_t *buf, int nb_sectors);
     void (*bdrv_close)(BlockDriverState *bs);
+    void (*bdrv_rebind)(BlockDriverState *bs);
     int (*bdrv_create)(const char *filename, QEMUOptionParameter *options);
     int (*bdrv_set_key)(BlockDriverState *bs, const char *key);
     int (*bdrv_make_empty)(BlockDriverState *bs);