Re: [Qemu-devel] [PATCH 1/7] vnvram: VNVRAM bdrv support

[Kevin Wolf <kwolf@redhat.com>]

Am 24.05.2013 um 17:33 hat Corey Bryant geschrieben:
> 
> 
> On 05/24/2013 09:06 AM, Kevin Wolf wrote:
> >Am 23.05.2013 um 19:44 hat Corey Bryant geschrieben:
> >>Provides low-level VNVRAM functionality that reads and writes data,
> >>such as an entry's binary blob, to a drive image using the block
> >>driver.
> >>
> >>Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
> >
> >>+/*
> >>+ * Increase the drive size if it's too small to fit the VNVRAM data
> >>+ */
> >>+static int vnvram_drv_adjust_size(VNVRAM *vnvram)
> >>+{
> >>+    int rc = 0;
> >>+    int64_t needed_size;
> >>+
> >>+    needed_size = 0;
> >>+
> >>+    if (bdrv_getlength(vnvram->bds) < needed_size) {
> >>+        rc = bdrv_truncate(vnvram->bds, needed_size);
> >>+        if (rc != 0) {
> >>+            DPRINTF("%s: VNVRAM drive too small\n", __func__);
> >>+        }
> >>+    }
> >>+
> >>+    return rc;
> >>+}
> >
> >This function doesn't make a whole lot of sense. It truncates the file
> >to size 0 if and only if bdrv_getlength() returns an error.
> >
> 
> There's a later patch that adds a "get size" function and changes
> the initialization of needed_size to the actual size needed to store
> VNVRAM data.  Anyway I should probably just include that change in
> this patch.  I think I'll still need this function or part of it
> with the new simplified approach that it looks like we're going to
> take.

Okay. But even then, do you really want to truncate on errors?

Kevin