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fdc: Make media change detection more robust 

fdctrl_change_cb() gets called on a virtual media change via monitor.
It would be nice if host device block drivers called it on physical
media change, but they don't.

bdrv_media_changed() lets you poll for media change, but it returns
"don't know" except with block driver "host_floppy".

FDrive member media_changed gets set on device initialization and by
fdctrl_change_cb(), and cleared by fdctrl_media_changed().  Thus, it's
set on first entry to fdctrl_media_changed() since device
initialization or virtual media change.

fdctrl_media_changed() ignores media_changed unless
bdrv_media_changed() returns "don't know".  If we change media via
monitor (setting media_changed), and the new media's block driver
returns 0, we lose.  Fortunately, "host_floppy" always returns 1 on
first call.  Brittle.  Clean it up not to rely on it.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Markus Armbruster 2011-08-03 15:08:09 +02:00 committed by Kevin Wolf
parent 8e49ca4624
commit 18d9005529
1 changed files with 8 additions and 4 deletions
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12
hw/fdc.c
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@ -898,11 +898,15 @@ static int fdctrl_media_changed(FDrive *drv)
if (!drv->bs)
return 0;
ret = bdrv_media_changed(drv->bs);
if (ret < 0) {
ret = drv->media_changed;
if (drv->media_changed) {
drv->media_changed = 0;
ret = 1;
} else {
ret = bdrv_media_changed(drv->bs);
if (ret < 0) {
ret = 0; /* we don't know, assume no */
}
}
drv->media_changed = 0;
if (ret) {
fd_revalidate(drv);
}