[PULL,23/48] block: Close backing file early in bdrv_img_create

Submitted by Stefan Hajnoczi on Dec. 6, 2013, 4:36 p.m.

Details

Message ID 1386347807-27359-24-git-send-email-stefanha@redhat.com
State New
Headers show

Commit Message

Stefan Hajnoczi Dec. 6, 2013, 4:36 p.m.
From: Max Reitz <mreitz@redhat.com>

Leaving the backing file open although it is not needed anymore can
cause problems if it is opened through a block driver which allows
exclusive access only and if the create function of the block driver
used for the top image (the one being created) tries to close and reopen
the image file (which will include opening the backing file a second
time).

In particular, this will happen with a backing file opened through
qemu-nbd and using qcow2 as the top image file format (which reopens the
image to flush it to disk).

In addition, the BlockDriverState in bdrv_img_create() is used for the
backing file only; it should therefore be made local to the respective
block.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

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diff --git a/block.c b/block.c
index 831c150..1c83ef1 100644
--- a/block.c
+++ b/block.c
@@ -4713,7 +4713,6 @@  void bdrv_img_create(const char *filename, const char *fmt,
 {
     QEMUOptionParameter *param = NULL, *create_options = NULL;
     QEMUOptionParameter *backing_fmt, *backing_file, *size;
-    BlockDriverState *bs = NULL;
     BlockDriver *drv, *proto_drv;
     BlockDriver *backing_drv = NULL;
     Error *local_err = NULL;
@@ -4792,6 +4791,7 @@  void bdrv_img_create(const char *filename, const char *fmt,
     size = get_option_parameter(param, BLOCK_OPT_SIZE);
     if (size && size->value.n == -1) {
         if (backing_file && backing_file->value.s) {
+            BlockDriverState *bs;
             uint64_t size;
             char buf[32];
             int back_flags;
@@ -4810,6 +4810,7 @@  void bdrv_img_create(const char *filename, const char *fmt,
                                  error_get_pretty(local_err));
                 error_free(local_err);
                 local_err = NULL;
+                bdrv_unref(bs);
                 goto out;
             }
             bdrv_get_geometry(bs, &size);
@@ -4817,6 +4818,8 @@  void bdrv_img_create(const char *filename, const char *fmt,
 
             snprintf(buf, sizeof(buf), "%" PRId64, size);
             set_option_parameter(param, BLOCK_OPT_SIZE, buf);
+
+            bdrv_unref(bs);
         } else {
             error_setg(errp, "Image creation needs a size parameter");
             goto out;
@@ -4847,9 +4850,6 @@  out:
     free_option_parameters(create_options);
     free_option_parameters(param);
 
-    if (bs) {
-        bdrv_unref(bs);
-    }
     if (error_is_set(&local_err)) {
         error_propagate(errp, local_err);
     }