commit e023b2e244ddcc25308309d20c6bfd037897b10c
author Paolo Bonzini <pbonzini@redhat.com> Tue May 08 16:51:41 2012 +0200
committer Kevin Wolf <kwolf@redhat.com> Thu May 10 10:32:12 2012 +0200
tree 154bfaea2368cfcbb39a2d2610dd9019510a14ff
parent 93e9eb6808c886f5f1c903b7ced1eed65de2ba39

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>

block.c

diff --git a/block.c b/block.c
index 3db84cd..87600a5 100644
--- a/block.c
+++ b/block.c
@@ -949,6 +949,13 @@
     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 @@
     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)

block/qed.c

diff --git a/block/qed.c b/block/qed.c
index 366cde7..30a31f9 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -367,6 +367,12 @@
     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 @@
     .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,

block/vvfat.c

diff --git a/block/vvfat.c b/block/vvfat.c
index 9ef21dd..2dc9d50 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -982,6 +982,12 @@
 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 @@
     .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,

block_int.h

diff --git a/block_int.h b/block_int.h
index 086832a..fbbc7ae 100644
--- a/block_int.h
+++ b/block_int.h
@@ -140,6 +140,7 @@
     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);